Donor Radii in Rare-Earth ComplexesClick to copy article linkArticle link copied!
- Charlene HarriswanglerCharlene HarriswanglerCentro Interdisciplinar de Química e Bioloxía (CICA) and Departamento de Química, Facultade de Ciencias, Universidade da Coruña, A Coruña 15071, Galicia , SpainMore by Charlene Harriswangler
- Juan C. Frías*Juan C. Frías*Email: [email protected]Departamento de Ciencias Biomédicas, Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, SpainMore by Juan C. Frías
- M. Teresa AlbeldaM. Teresa AlbeldaInstituto de Ciencia Molecular (ICMol), Departamento de Química Inorgánica, Universidad de Valencia, 46980 Paterna, SpainDepartamento de Química Inorgánica, Universidad de Valencia, C/Dr. Moliner 50, 46100 Burjasot, Valencia, SpainMore by M. Teresa Albelda
- Laura ValenciaLaura ValenciaDepartamento de Química Inorgánica, Facultad de Ciencias, Universidade de Vigo, As Lagoas, Marcosende, 36310 Pontevedra, SpainMore by Laura Valencia
- Enrique García-EspañaEnrique García-EspañaInstituto de Ciencia Molecular (ICMol), Departamento de Química Inorgánica, Universidad de Valencia, 46980 Paterna, SpainMore by Enrique García-España
- David Esteban-GómezDavid Esteban-GómezCentro Interdisciplinar de Química e Bioloxía (CICA) and Departamento de Química, Facultade de Ciencias, Universidade da Coruña, A Coruña 15071, Galicia , SpainMore by David Esteban-Gómez
- Carlos Platas-Iglesias*Carlos Platas-Iglesias*Email: [email protected]Centro Interdisciplinar de Química e Bioloxía (CICA) and Departamento de Química, Facultade de Ciencias, Universidade da Coruña, A Coruña 15071, Galicia , SpainMore by Carlos Platas-Iglesias
Abstract
We present a set of donor radii for the rare-earth cations obtained from the analysis of structural data available in the Cambridge Structural Database (CSD). Theoretical calculations using density functional theory (DFT) and wave function approaches (NEVPT2) demonstrate that the Ln-donor distances can be broken down into contributions of the cation and the donor atom, with the minimum in electron density (ρ) that defines the position of (3,–1) critical points corresponding well with Shannon’s crystal radii (CR). Subsequent linear fits of the experimental bond distances for all rare earth cations (except Pm3+) afforded donor radii (rD) that allow for the prediction of Ln-donor distances regardless of the nature of the rare-earth cation and its oxidation state. This set of donor radii can be used to rationalize structural data and identify particularly weak or strong interactions, which has important implications in the understanding of the stability and reactivity of complexes of these metal ions. A few cases of incorrect atom assignments in X-ray structures were also identified using the derived rD values.
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License Summary*
You are free to share(copy and redistribute) this article in any medium or format and to adapt(remix, transform, and build upon) the material for any purpose, even commercially within the parameters below:
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Synopsis
Lanthanide-donor distances can be estimated by using crystal radii and donor radii, which were obtained from the simultaneous analysis of a large number of X-ray structures of lanthanide complexes.
Introduction
Results and Discussion
Description of the Data Set
Bond Distances
Calculated Electron Densities
Donor Radii
rD (Å)c | Δd1/2 (Å) | x0 (Å × 103) | |
---|---|---|---|
NAM | 1.425 ± 0.001 | 0.097 | –7.58 |
OC | 1.132 ± 0.001 | 0.071 | –3.62 |
OA | 1.130 ± 0.002 | 0.062 | –10.2 |
Cl | 1.451 ± 0.014 | b | b |
F | 0.915 ± 0.008 | b | b |
OPO3 | 1.114 ± 0.004 | 0.067 | –1.82 |
OPRO2 | 1.106 ± 0.002 | 0.077 | –0.44 |
NPY | 1.329 ± 0.003 | 0.053 | –4.71 |
OTf | 1.183 ± 0.007 | b | b |
OW | 1.231 ± 0.004 | 0.123 | –26.3 |
OOH | 1.157 ± 0.006 | 0.058 | –2.51 |
NAM, amine nitrogen; OC, carboxylate oxygen; OA, amide oxygen; Cl, chloride anion; F, fluoride anion; OPO3, phosphonate oxygen; OPRO2, phosphinate oxygen; NPY, pyridine nitrogen; OTf, Triflate oxygen; OW, water oxygen; OOH, alcohol oxygen.
The limited number of data available prevented accurate Gaussian fitting.
These values can be also used in combination with IR by adding 0.14 Å to the corresponding donor radius. The errors correspond to the standard deviations of the linear fits (see text).
Conclusions
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.inorgchem.3c03126.
Computational details, crystallographic data (CCDC 2266985), additional plots showing calculated electron densities, linear fits according to eq 1, and bond distances used in this work with CSD codes (PDF)
CCDC 2266985 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
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Acknowledgments
This research was funded by the Spanish Ministry for Science and Innovation, the National Research Agency and FEDER funds from the EU (grants PID2019-104626GB-I00, PID2019-110751RB-I00, and RED2022-134091-T), Xunta de Galicia (ED431B 2020/52), and the Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital of the Generalitat Valenciana (PROMETEO Grant CIPROM/2021/030). This contribution is also based upon work from COST Action CA18202, NECTAR - Network for Equilibria and Chemical Thermodynamics Advanced Research, supported by COST (European Cooperation in Science and Technology). C.H. thanks Ministerio Ciencia e Innovación (Grant PRE2020-092888) for funding her PhD contract. The authors also thank Centro de Supercomputación de Galicia (CESGA) for providing the supercomputing facilities.
References
This article references 94 other publications.
- 1Parker, D.; Dickins, R. S.; Puschmann, H.; Crossland, C.; Howard, J. A. K. Being Excited by Lanthanide Coordination Complexes: Aqua Species, Chirality, Excited-State Chemistry, and Exchange Dynamics. Chem. Rev. 2002, 102, 1977– 2010, DOI: 10.1021/cr010452+Google Scholar1https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38Xjslens7c%253D&md5=0e63a0a7979334bb84c640320528be70Being Excited by Lanthanide Coordination Complexes: Aqua Species, Chirality, Excited-State Chemistry, and Exchange DynamicsParker, David; Dickins, Rachel S.; Puschmann, Horst; Crossland, Clare; Howard, Judith A. K.Chemical Reviews (Washington, DC, United States) (2002), 102 (6), 1977-2010CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. Lanthanide (Ln) coordination complexes are reviewed with emphasis on structural anal. of 9-coordinate aqua-Ln species, chirality in aq. soln., exchange dynamics, excited-state chem. and magnetic resonance applications.
- 2Marcus, Y. Thermodynamics of Solvation of Ions. J. Chem. Soc., Faraday Trans. 1991, 87, 2995– 2999, DOI: 10.1039/FT9918702995Google Scholar2https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3MXmsVWhsbc%253D&md5=96b15991eae292d32845508f6c99a5a7Thermodynamics of solvation of ions. 5. Gibbs free energy of hydration at 298.15 KMarcus, YizhakJournal of the Chemical Society, Faraday Transactions (1991), 87 (18), 2995-9CODEN: JCFTEV; ISSN:0956-5000.The std. molar free energies of hydration, ΔhvdG0, of 109 (mainly inorg.) ions ranging in their charges from -3 to +4 were compiled and interpreted in terms of a model used previously for other thermodn. quantities of hydration. The main contributions to ΔhydG0 are the electrostatic effects, resulting in solvent immobilization, electrostriction, and dielec. satn. in a hydration shell of specified thickness, and further such effects on the water that surrounds this shell. Other effects contribute to ΔhydG0 to a minor extent only.
- 3Regueiro-Figueroa, M.; Esteban-Gómez, D.; de Blas, A.; Rodríguez-Blas, T.; Platas-Iglesias, C. Understanding Stability Trends along the Lanthanide Series. Chem. – Eur. J. 2014, 20 (14), 3974– 3981, DOI: 10.1002/chem.201304469Google Scholar3https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXjt12gtrg%253D&md5=8a2ef02e4bef4d8ad4e62c25243a08ddUnderstanding Stability Trends along the Lanthanide SeriesRegueiro-Figueroa, Martin; Esteban-Gomez, David; de Blas, Andres; Rodriguez-Blas, Teresa; Platas-Iglesias, CarlosChemistry - A European Journal (2014), 20 (14), 3974-3981CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)The stability trends across the lanthanide series of complexes with the polyaminocarboxylate ligands TETA4- (H4TETA = 2,2',2'',2'''-(1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrayl)tetraacetic acid), BCAED4- (H4BCAED = 2,2',2'',2'''-{[(1,4-diazepane-1,4-diyl)bis(ethane-2,1-diyl)]bis(azanetriyl)}tetraacetic acid), and BP18C62- (H2BP18C6 = 6,6'-[(1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene)]dipicolinic acid) were investigated using DFT calcns. Geometry optimizations performed at the TPSSh/6-31G(d,p) level, and using a 46 + 4fn ECP for lanthanides, provide bond lengths of the metal coordination environments in good agreement with the exptl. values obsd. in the X-ray structures. The contractions of the Ln3+ coordination spheres follow quadratic trends, as obsd. previously for different isostructural series of complexes. We show here that the parameters obtained from the quant. anal. of these data can be used to rationalize the obsd. stability trends across the 4f period. The stability trends along the lanthanide series were also evaluated by calcg. the free energy for the reaction [La(L)]n+/-(sol) + Ln3+(sol)→[Ln(L)]n+/-(sol) + La3+(sol). A parameterization of the Ln3+ radii was performed by minimizing the differences between exptl. and calcd. std. hydration free energies. The calcd. stability trends are in good agreement with the exptl. stability consts., which increase markedly across the series for BCAED4- complexes, increase smoothly for the TETA4- analogs, and decrease in the case of BP18C62- complexes. The resulting stability trend is the result of a subtle balance between the increased binding energies of the ligand across the lanthanide series, which contribute to an increasing complex stability, and the increase in the abs. values of hydration energies along the 4f period.
- 4Pearson, R. Hard and Soft Acids and Bases. J. Am. Chem. Soc. 1963, 85, 3533– 3539, DOI: 10.1021/ja00905a001Google Scholar4https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF2cXksV0%253D&md5=2333a18c8168b373b612f5f45e8f4b4cHard and soft acids and basesPearson, Ralph G.Journal of the American Chemical Society (1963), 85 (22), 3533-9CODEN: JACSAT; ISSN:0002-7863.A number of Lewis acids of diverse types are classified as (a) or (b) following the criterion of Ahrland, et al. (CA 53, 960c). Other, auxiliary criteria are proposed. Class (a) acids prefer to bind to "hard" or nonpolarizable bases. Class (b) acids prefer to bind to "soft" or polarizable bases. Since class (a) acids are themselves "hard" and since class (b) acids are "soft" a simple, useful rule is proposed: hard acids bind strongly to hard bases and soft acids bind strongly to soft bases. The explanations for such behavior include: (1) various degrees of ionic and covalent σ-bonding; (2) π-bonding; (3) electron correlation phenomena; (4) solvation effects.
- 5Cotton, S. A. Establishing Coordination Numbers for the Lanthanides in Simple Complexes. C. R. Chim. 2005, 8 (2), 129– 145, DOI: 10.1016/j.crci.2004.07.002Google Scholar5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXhtlOgt7w%253D&md5=1e8d7ff840544ef9f9045aca9095dcb9Establishing coordination numbers for the lanthanides in simple complexesCotton, Simon A.Comptes Rendus Chimie (2005), 8 (2), 129-145CODEN: CRCOCR; ISSN:1631-0748. (Editions Scientifiques et Medicales Elsevier)A review. This article reviews the development of the understanding of the coordination no. in lanthanide complexes, showing how it was realized in the 1960s that lanthanide complexes frequently had much higher coordination nos. than 6, and how it subsequently became possible for chemists to synthesize compds. with coordination nos. as low as 2, 3 and 4. Subsequent sections examine how coordination of solvent can cause uncertainties in coordination nos.; the detn. of the coordination no. of the aqua ions and in hydrated salts; variations (or not) in coordination no. across the lanthanide series; the effect of counterion upon coordination no.; and agostic interactions and interactions with distant atoms (when is a bond not a bond).
- 6Bünzli, J.-C. G. Review: Lanthanide Coordination Chemistry: From Old Concepts to Coordination Polymers. J. Coord. Chem. 2014, 67 (23–24), 3706– 3733, DOI: 10.1080/00958972.2014.957201Google ScholarThere is no corresponding record for this reference.
- 7Moeller, T.; Thompson, L. C. Observations on the Rare Earths--LXXV. The Stabilities of Diethylenetriaminepentaacetic Acid Chelates. J. Inorg. Nucl. Chem. 1962, 24, 499– 510, DOI: 10.1016/0022-1902(62)80236-XGoogle Scholar7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF3sXisV2lug%253D%253D&md5=c1623277d4bde5a9040aefeb8fdbd415The rare earths. LXXV. The stabilities of diethylenetriaminepentaacetic acid chelatesMoeller, T.; Thompson, L. C.Journal of Inorganic and Nuclear Chemistry (1962), 24 (), 499-510CODEN: JINCAO; ISSN:0022-1902.cf. CA 56, 6727b, 11002h. The interaction between diethylenetriaminepentaacetic acid (H5DTPA or H5Z) and rare earth metal ions (Ln+++) was investigated. The acid formation consts. of the H chelates (LnHZ-) and the formation consts. of the normal chelates (LnZ--) were obtained at 10, 20, and 30°, and an ionic strength of 0.1 (KNO3), the former by a titration technique and the latter by a Hg indicator electrode technique. δH° and δS° were detd. Although errors in these functions are substantial, the functions were related to observed trends in stability. The dissocn. consts. for the last 3 protons of diethylenetriaminepentaacetic acid were measured as a function of temp. at ionic strength 0.1 (KNO3) and converted to thermodynamic functions by least squares analysis. These functions were compared with corresponding values for related chelating agents.
- 8Loncin, M. F.; Desreux, J. F.; Merciny, E. Coordination of Lanthanides by Two Polyamino Polycarboxylic Macrocycles: Formation of Highly Stable Lanthanide Complexes. Inorg. Chem. 1986, 25 (15), 2646– 2648, DOI: 10.1021/ic00235a031Google Scholar8https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL28XktlSru7Y%253D&md5=4c39cb8d450f964098f9844771f5f07dCoordination of lanthanides by two polyamino polycarboxylic macrocycles: formation of highly stable lanthanide complexesLoncin, M. F.; Desreux, J. F.; Merciny, E.Inorganic Chemistry (1986), 25 (15), 2646-8CODEN: INOCAJ; ISSN:0020-1669.The formation consts. of a few lanthanide complexes with DOTA (1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid) and TETA (1,4,8,11-tetraazacyclotetradecane-N,N',N'',N'''-tetraacetic acid) were measured by potentiometric and competition methods. The ligand DOTA forms the most stable lanthanide chelates known so far (log KML = 28.2-29.2) while the stability of the TETA compds. at 80° (log KML = 14.5-16.5) is comparable to the stability of the EDTA complexes. A competition method with the C2O42- anion as a probe had to be used for detg. the formation consts. of the DOTA lanthanide chelates because of the high stability of these compds. The relative stability of the DOTA and TETA complexes is accounted for by steric factors with ref. to known soln.- and solid-state structures.
- 9Clough, T. J.; Jiang, L.; Wong, K.-L.; Long, N. J. Ligand Design Strategies to Increase Stability of Gadolinium-Based Magnetic Resonance Imaging Contrast Agents. Nat. Commun. 2019, 10 (1), 1420, DOI: 10.1038/s41467-019-09342-3Google Scholar9https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB3cbps1GhsA%253D%253D&md5=1b6079d3ddddbd8b72eb7901c6d0ec3eLigand design strategies to increase stability of gadolinium-based magnetic resonance imaging contrast agentsClough Thomas J; Jiang Lijun; Long Nicholas J; Jiang Lijun; Wong Ka-LeungNature communications (2019), 10 (1), 1420 ISSN:.Gadolinium(III) complexes have been widely utilised as magnetic resonance imaging (MRI) contrast agents for decades. In recent years however, concerns have developed about their toxicity, believed to derive from demetallation of the complexes in vivo, and the relatively large quantities of compound required for a successful scan. Recent efforts have sought to enhance the relaxivity of trivalent gadolinium complexes without sacrificing their stability. This review aims to examine the strategic design of ligands synthesised for this purpose, provide an overview of recent successes in gadolinium-based contrast agent development and assess the requirements for clinical translation.
- 10Uzal-Varela, R.; Rodríguez-Rodríguez, A.; Wang, H.; Esteban-Gómez, D.; Brandariz, I.; Gale, E. M.; Caravan, P.; Platas-Iglesias, C. Prediction of Gd(III) Complex Thermodynamic Stability. Coord. Chem. Rev. 2022, 467, 214606 DOI: 10.1016/j.ccr.2022.214606Google Scholar10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhtlOrs7vO&md5=817d25df92de6eb2acc1c7a99c13031bPrediction of Gd(III) complex thermodynamic stabilityUzal-Varela, Rocio; Rodriguez-Rodriguez, Aurora; Wang, Huan; Esteban-Gomez, David; Brandariz, Isabel; Gale, Eric M.; Caravan, Peter; Platas-Iglesias, CarlosCoordination Chemistry Reviews (2022), 467 (), 214606CODEN: CCHRAM; ISSN:0010-8545. (Elsevier B.V.)Gadolinium(III) complexes are widely employed as contrast agents in diagnostic magnetic resonance imaging, and the development of new contrast agents remains a highly active field. A key requisite for contrast agents is high thermodn. stability of the complex to ensure that the Gd(III) ion is not released in the body. Here we utilized published stability consts. spanning 20 orders of magnitude to develop empirical expressions based on structural descriptors to predict the Gd(III)-ligand formation const. as well as pGd at pH 7.4. We then tested the predictive power of these expressions and found excellent agreement with a mean deviation of 1.0 log K units. The magnitudes of the structural descriptors are useful for guiding ligand design for Gd(III), and the empirical stability const. expressions can be used to screen potential ligands. This methodol. is readily extended to other aq. metal ion systems.
- 11Wahsner, J.; Gale, E. M.; Rodríguez-Rodríguez, A.; Caravan, P. Chemistry of MRI Contrast Agents: Current Challenges and New Frontiers. Chem. Rev. 2019, 119 (2), 957– 1057, DOI: 10.1021/acs.chemrev.8b00363Google Scholar11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhvFWhsLfM&md5=3bf91b184710feb5d10f3249eff7ac02Chemistry of MRI Contrast Agents: Current Challenges and New FrontiersWahsner, Jessica; Gale, Eric M.; Rodriguez-Rodriguez, Aurora; Caravan, PeterChemical Reviews (Washington, DC, United States) (2019), 119 (2), 957-1057CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. Tens of millions of contrast-enhanced magnetic resonance imaging (MRI) exams are performed annually around the world. The contrast agents, which improve diagnostic accuracy, are almost exclusively small, hydrophilic gadolinium(III) based chelates. In recent years concerns have arisen surrounding the long-term safety of these compds., and this has spurred research into alternatives. There has also been a push to develop new molecularly targeted contrast agents or agents that can sense pathol. changes in the local environment. This comprehensive review describes the state of the art of clin. approved contrast agents, their mechanism of action, and factors influencing their safety. From there we describe different mechanisms of generating MR image contrast such as relaxation, chem. exchange satn. transfer, and direct detection and the types of mols. that are effective for these purposes. Next we describe efforts to make safer contrast agents either by increasing relaxivity, increasing resistance to metal ion release, or by moving to gadolinium(III)-free alternatives. Finally we survey approaches to make contrast agents more specific for pathol. either by direct biochem. targeting or by the design of responsive or activatable contrast agents.
- 12Kostelnik, T. I.; Orvig, C. Radioactive Main Group and Rare Earth Metals for Imaging and Therapy. Chem. Rev. 2019, 119 (2), 902– 956, DOI: 10.1021/acs.chemrev.8b00294Google Scholar12https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitVenu7bP&md5=5ea88568fccd143b1c617130cbfe6a08Radioactive Main Group and Rare Earth Metals for Imaging and TherapyKostelnik, Thomas I.; Orvig, ChrisChemical Reviews (Washington, DC, United States) (2019), 119 (2), 902-956CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)Radiometals possess an exceptional breadth of decay properties and have been applied to medicine with great success for several decades. The majority of current clin. use involves diagnostic procedures, which use either positron-emission tomog. (PET) or single-photon imaging to detect anat. abnormalities that are difficult to visualize using conventional imaging techniques (e.g., MRI and X-ray). The potential of therapeutic radiometals has more recently been realized and relies on ionizing radiation to induce irreversible DNA damage, resulting in cell death. In both cases, radiopharmaceutical development has been largely geared toward the field of oncol.; thus, selective tumor targeting is often essential for efficacious drug use. To this end, the rational design of four-component radiopharmaceuticals has become popularized. This Review introduces fundamental concepts of drug design and applications, with particular emphasis on bifunctional chelators (BFCs), which ensure secure consolidation of the radiometal and targeting vector and are integral for optimal drug performance. Also presented are detailed accounts of prodn., chelation chem., and biol. use of selected main group and rare earth radiometals.
- 13Bünzli, J.-C. G. Lanthanide Luminescence for Biomedical Analyses and Imaging. Chem. Rev. 2010, 110 (5), 2729– 2755, DOI: 10.1021/cr900362eGoogle Scholar13https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhvFGqu7o%253D&md5=d042b6946d5b26f5ac056182fc9a3ecbLanthanide Luminescence for Biomedical Analyses and ImagingBunzli, Jean-Claude G.Chemical Reviews (Washington, DC, United States) (2010), 110 (5), 2729-2755CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. This review addresses the problematics of lanthanide luminescent bioprobes (LLB) from the standpoint of their photophys. and biochem. properties; a broad overview of the various applications in which LLBs have been applied is given.
- 14Bünzli, J.-C. G. On the Design of Highly Luminescent Lanthanide Complexes. Coord. Chem. Rev. 2015, 293–294, 19– 47, DOI: 10.1016/j.ccr.2014.10.013Google Scholar14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvFSmtbzF&md5=4d963c71116add3fd9f9f1de5c4b96c4On the design of highly luminescent lanthanide complexesBunzli, Jean-Claude G.Coordination Chemistry Reviews (2015), 293-294 (), 19-47CODEN: CCHRAM; ISSN:0010-8545. (Elsevier B.V.)Presently, phosphors and luminescent materials for lighting, telecommunications, displays, security inks and marking, as well as for probes in biosciences represent one third of the total value of the lanthanides used worldwide. If optical glasses and laser materials are added, this figure is close to 40%, explaining the large interest that the scientific community is devoting to such materials. The present review focuses on the design of highly luminescent lanthanide complexes and discusses all aspects needing optimization. Ref. is made to the mastering of the various energy migration processes in luminescence sensitization by org. ligands, to minimizing non-radiative deactivation mechanisms, as well as to other parameters such as the radiative lifetime, the refractive index, and the benefit of inserting luminescent complexes into inorg.-hybrid structures. Comparative tables list the most luminescent complexes emitting in the visible and near-IR ranges and the best chromophores are pointed out.
- 15Nonat, A. M.; Charbonnière, L. J. Upconversion of Light with Molecular and Supramolecular Lanthanide Complexes. Coord. Chem. Rev. 2020, 409, 213192 DOI: 10.1016/j.ccr.2020.213192Google Scholar15https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhvFartrg%253D&md5=10f2d7aee5a57b6ba10a3ba81ef2cc6cUpconversion of light with molecular and supramolecular lanthanide complexesNonat, Aline M.; Charbonniere, Loic J.Coordination Chemistry Reviews (2020), 409 (), 213192CODEN: CCHRAM; ISSN:0010-8545. (Elsevier B.V.)A review. Upconversion (UC) is the process by which the energy of multiple photons is absorbed by a compd. and restored in the form of a photon of higher energy than the incident light, resulting in an anti-Stokes process. Although studied theor. since the middle of the last century and exptl. obsd. in the 1960's, the process was up to recently mainly restricted to solid state devices and ultimately to nanoparticles at the end of the century. At the same period, different researches were directed towards the possibility to observe UC at the mol. level and it is only recently that the phenomenon could be obsd. in discrete mol. entities in soln. with still very few examples. This review aims at explaining the difficulties encountered at the mol. level compared to the solid state and summarizes the results reported to date on UC at the mol. scale.
- 16Aboshyan-Sorgho, L.; Cantuel, M.; Petoud, S.; Hauser, A.; Piguet, C. Optical Sensitization and Upconversion in Discrete Polynuclear Chromium–Lanthanide Complexes. Coord. Chem. Rev. 2012, 256 (15–16), 1644– 1663, DOI: 10.1016/j.ccr.2011.12.013Google Scholar16https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhslGls7k%253D&md5=98b1b975355f94479b58e79a64102348Optical sensitization and upconversion in discrete polynuclear chromium-lanthanide complexesAboshyan-Sorgho, Lilit; Cantuel, Martine; Petoud, Stephane; Hauser, Andreas; Piguet, ClaudeCoordination Chemistry Reviews (2012), 256 (15-16), 1644-1663CODEN: CCHRAM; ISSN:0010-8545. (Elsevier B.V.)A review. Due to its extreme kinetic inertness, trivalent chromium, Cr(III), has been rarely combined with labile trivalent lanthanides, Ln(III), to give discrete self-assembled (supra)mol. polynuclear complexes. However, the plethora of accessible metal-centered excited states possessing variable lifetimes and emissive properties, combined with the design of efficient intramol. Cr(III) ↔ Ln(III) energy transfer processes open attractive perspectives for programming directional light-conversion within these heterometallic mols. Efforts made to address this exciting challenge for both light-sensitization and light-upconversion are discussed in this article.
- 17Bernot, K.; Daiguebonne, C.; Calvez, G.; Suffren, Y.; Guillou, O. A Journey in Lanthanide Coordination Chemistry: From Evaporable Dimers to Magnetic Materials and Luminescent Devices. Acc. Chem. Res. 2021, 54 (2), 427– 440, DOI: 10.1021/acs.accounts.0c00684Google Scholar17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsFKiuw%253D%253D&md5=855276c6c5033d7d3dbe98d01afa0d73A Journey in Lanthanide Coordination Chemistry: From Evaporable Dimers to Magnetic Materials and Luminescent DevicesBernot, Kevin; Daiguebonne, Carole; Calvez, Guillaume; Suffren, Yan; Guillou, OlivierAccounts of Chemical Research (2021), 54 (2), 427-440CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)A review. Conspectus: Lanthanide ions are prime ingredients for the design of compds., materials, and devices with unique magnetic and optical properties. Accordingly, coordination chem. is one of the best tools for building mol. edifices from these ions because it allows careful control of the ions' environment and of the dimensionality of the final compd. In this Account, the authors review the authors' results on lanthanide-based dimers. A pure fundamental study on lanthanide coordination chem. allows the study of a full continuum of results from the compd. to materials and then to devices. The conversion of mols. into materials is a tricky task because it requires strong mol. robustness toward the surface deposition processes as well as the preservation and detectability of the mol. properties in the material. Addnl., the passage of a material toward a device implies a material with a given function, for example, a tailored response to an external stimulus. To do so, the authors targeted neutral and isolated mols. whose transfer on surfaces by chemi- or physisorption is much easier than that of charged mols. or extended coordination networks. Then, the authors focused on mols. with very strong evaporability to avoid wet chem. deposition processes that are more likely to damage the mols. and/or distort their geometries. The authors thus designed lanthanide dimers based on fluorinated β-diketonates and pyridine-N-oxide ligands. As expected, they show remarkable evaporability but also strong luminescence and interesting magnetic behavior because they behave as single-mol. magnets (SMMs). Ligand substitutions and stoichiometric modifications allow the optimization of the geometric organization of the dimers in the crystal packing as well as their evaporability, SMM behavior, luminescent properties, or their ability to be anchored on surfaces. Most of all, this family of mols. shows a strong ability to form thick films on various substrates. This allows converting these mols. to magnetic materials and luminescent devices. Magnetic materials can be designed by creating thick films of the dimers deposited on gold. These films were designed and studied with the most advanced techniques of on-surface imaging (at. force microscopy, AFM), on-surface physicochem. characterization (XPS, time of flight-secondary ion mass spectroscopy (Tof-SIMS)), and on-surface magnetic study (low-energy muon spin relaxation (LE-μSR)). Contrary to what was previously obsd. on other SMM films, no depth dependence of the SMM behavior was obsd. This means that the dimers do not suffer from the vacuum or substrate interface and behave similarly, whatever their localization. This exceptional magnetic robustness is a key ingredient in the creation of materials for mol. magnetic data storage. Luminescent devices can be obtained by layering mol. films of the dimers with a copper-rich solid-state electrolyte between ITO/Pt electrodes. The electromigration of Cu2+ ions into films of Eu3+, Tb3+, and Dy3+ dimers quenches their luminescence. This luminescence tuning by electromigration is reversible, and this setup can be considered to be a proof of concept of full solid-state luminescent device where reversible coding can be tailored by an elec. field. It is envisioned for optical data storage purposes. In the future, it could also benefit from the SMM properties of the mols. to pave the way toward multifunctional mol. data storage devices.
- 18Cucinotta, G.; Perfetti, M.; Luzon, J.; Etienne, M.; Car, P.-E.; Caneschi, A.; Calvez, G.; Bernot, K.; Sessoli, R. Magnetic Anisotropy in a Dysprosium/DOTA Single-Molecule Magnet: Beyond Simple Magneto-Structural Correlations. Angew. Chem., Int. Ed. 2012, 51 (7), 1606– 1610, DOI: 10.1002/anie.201107453Google Scholar18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xmt1KksA%253D%253D&md5=836f08c6ae8f81c1240506b8dc5c780fMagnetic Anisotropy in a Dysprosium/DOTA Single-Molecule Magnet: Beyond Simple Magneto-Structural CorrelationsCucinotta, Giuseppe; Perfetti, Mauro; Luzon, Javier; Etienne, Mael; Car, Pierre-Emmanuel; Caneschi, Andrea; Calvez, Guillaume; Bernot, Kevin; Sessoli, RobertaAngewandte Chemie, International Edition (2012), 51 (7), 1606-1610, S1606/1-S1606/11CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Single-crystal magnetic investigations have been shown to be required to study mol. systems that are based on anisotropic lanthanide ions. The detailed exptl. and theor. investigation on one of the most studied lanthanide coordination compds. has provided several key results. The most important one is that simple magnetostructural correlations based on the coordination environment can fail to predict, even approx., the correct magnetic anisotropy of anisotropic lanthanide ions in a low-symmetry environment. Subtle structural details, like the position of hydrogen atoms and the consequent orientation of the nonbonding orbitals of the axial ligand can overcome the symmetry imposed by the coordination polyhedron. The well-resolved luminescence spectra, which allow the energy splitting of the 6H15n multiplet to be detd., have provided precious indications, which confirm that the first excited doublet plays a key role in the magnetization dynamics. .Finally, post Hartree-Fock ab initio calcns. were confirmed to be an invaluable method for the prediction and rationalization of the magnetic anisotropy, provided that subtle structural details are also correctly taken into account. The evaluation of the energy splitting seems, however, even more critically dependent on which structural model and basis sets are used. In modeling the relaxivity effects it is generally assumed that the orientation of the M-Owater of DOTA-like complexes corresponds to the anisotropy axis and that the apical water mols. lie in the cone of highest susceptibility. The authors have shown here that this is probably not the case and we also suspect that the mechanism of contrast in the nuclear relaxation is more complex because the labile water mol. modifies the magnetic anisotropy of the lanthanide ion.
- 19Shannon, R. D. Revised Effective Ionic Radii and Systematic Studies of Interatomic Distances in Halides and Chaleogenides. Acta Crystallogr., A 1976, 32, 751– 767, DOI: 10.1107/S0567739476001551Google ScholarThere is no corresponding record for this reference.
- 20Baloch, A. A. B.; Alqahtani, S. M.; Mumtaz, F.; Muqaibel, A. H.; Rashkeev, S. N.; Alharbi, F. H. Extending Shannon’s Ionic Radii Database Using Machine Learning. Phys. Rev. Mater. 2021, 5 (4), 043804 DOI: 10.1103/PhysRevMaterials.5.043804Google Scholar20https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhtVyht73N&md5=acbef731ed4287c03076b96d818d9d7aExtending Shannon's ionic radii database using machine learningBaloch, Ahmer A. B.; Alqahtani, Saad M.; Mumtaz, Faisal; Muqaibel, Ali H.; Rashkeev, Sergey N.; Alharbi, Fahhad H.Physical Review Materials (2021), 5 (4), 043804CODEN: PRMHBS; ISSN:2475-9953. (American Physical Society)In computational material design, ionic radius is one of the most important phys. parameters used to predict material properties. Motivated by the progress in computational materials science and material informatics, we extend the renowned Shannon's table from 475 ions to 987 ions. Accordingly, a rigorous machine learning (ML) approach is employed to extend the ionic radii table using all possible combinations of oxidn. states (OS) and coordination nos. (CN) available in crystallog. repositories. An ionic-radius regression model for Shannon's database is developed as a function of the period no., the valence orbital configuration, OS, CN, and ionization potential. In the Gaussian process regression (GPR) model, the reached R2 accuracy is 99while the root mean square error of radii is 0.0332 Å. The optimized GPR model is then employed for predicting a new set of ionic radii for uncommon combinations of OS and CN extd. by harnessing crystal structures from materials project databases. The generated data are consolidated with the reputable Shannon's data and are made available online in a database repository.
- 21Lundberg, D.; Persson, I.; Eriksson, L.; D’Angelo, P.; De Panfilis, S. Structural Study of the N,N′ -Dimethylpropyleneurea Solvated Lanthanoid(III) Ions in Solution and Solid State with an Analysis of the Ionic Radii of Lanthanoid(III) Ions. Inorg. Chem. 2010, 49 (10), 4420– 4432, DOI: 10.1021/ic100034qGoogle Scholar21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXkslKlsr4%253D&md5=da9fc684010ea5eefb2635dadcd8df87Structural Study of the N,N'-Dimethylpropyleneurea Solvated Lanthanoid(III) Ions in Solution and Solid State with an Analysis of the Ionic Radii of Lanthanoid(III) IonsLundberg, Daniel; Persson, Ingmar; Eriksson, Lars; D'Angelo, Paola; De Panfilis, SimoneInorganic Chemistry (2010), 49 (10), 4420-4432CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)The structures of the N,N'-dimethylpropyleneurea (dmpu) solvated lanthanoid(III) ions have been studied in dmpu soln. (La-Nd, Sm-Lu) and in solid iodide salts (La-Nd, Sm, Gd-Lu) by extended X-ray absorption fine structure (EXAFS), and single crystal X-ray diffraction (La, Pr, Nd, Gd, Tb, Er, Yb, and Lu); the EXAFS studies were performed on both K and LIII absorption edges. Because of the space-demanding properties of dmpu upon coordination, dmpu solvated metal ions often show coordination nos. lower than those found in corresponding hydrates and solvates of oxygen donor solvents without steric requirements beyond the size of the donor atom. All lanthanoid(III) ions are seven-coordinate in soln., except lutetium(III) which is six-coordinated in regular octahedral fashion, whereas in the solid iodide salts the dmpu solvated lanthanoid(III) ions are all six-coordinate in regular octahedral fashion. A comparison of Ln-O bond lengths in a large no. of lanthanoid(III) complexes with neutral oxygen donor ligands and different configurations shows that the metal ion-oxygen distance is specific for each coordination no. with a narrow bond distance distribution. This also shows that the radius of the coordinated oxygen atom in these compds. can be assumed to be 1.34 Å as proposed for coordinated water, while for ethers such as THF it is somewhat larger. Using this at. radius of oxygen in coordinated water mols., we have calcd. the ionic radii of the lanthanoid(III) ions in four- to nine-coordination and evaluated using the bond lengths reported for homo- and heteroleptic complexes in oxygen donor solvates in soln. and solid state. This yields new and revised ionic radii which in some instances are significantly different from the ionic radii normally referenced in the literature, including interpolated values for the elusive promethium(III) ion.
- 22Seitz, M.; Oliver, A. G.; Raymond, K. N. The Lanthanide Contraction Revisited. J. Am. Chem. Soc. 2007, 129 (36), 11153– 11160, DOI: 10.1021/ja072750fGoogle Scholar22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXpt1Whsbc%253D&md5=dfdea2fc3d2d5930b26f8df0a6bc004fThe Lanthanide Contraction RevisitedSeitz, Michael; Oliver, Allen G.; Raymond, Kenneth N.Journal of the American Chemical Society (2007), 129 (36), 11153-11160CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)A complete, isostructural series of complexes with La-Lu (except Pm) with the ligand TREN-1,2-HOIQO (I), [M(TREN-1,2-HOIQO-3H)(H2O)]·H2O, was synthesized and structurally characterized by single-crystal x-ray anal. All complexes are 1-dimensional polymeric species in the solid state, with the lanthanide being in an eight-coordinate, distorted trigonal-dodecahedral environment with a donor set of eight unique oxygen atoms. This series constitutes the 1st complete set of isostructural complexes from La-Lu (without Pm) with a ligand of denticity greater than two. The geometric arrangement of the chelating moieties slightly deviates across the lanthanide series, as analyzed by a shape parameter metric based on the comparison of the dihedral angles along all edges of the coordination polyhedron. The apparent lanthanide contraction in the individual Ln-O bond lengths deviates considerably from the expected quadratic decrease that was found previously in a no. of complexes with ligands of low denticity. The sum of all bond lengths around the trivalent metal cation, however, is more regular, showing an almost ideal quadratic behavior across the entire series. The quadratic nature of the lanthanide contraction is derived theor. from Slater's model for the calcn. of ionic radii. The sum of all distances along the edges of the coordination polyhedron show exactly the same quadratic dependence as the Ln-X bond lengths. The universal validity of this coordination sphere contraction, concomitant with the quadratic decrease in Ln-X bond lengths, was confirmed by reexamn. of four other, previously published series of lanthanide complexes. Owing to the importance of multidentate ligands for the chelation of rare-earth metals, this result provides a significant advance for the prediction and rationalization of the geometric features of the corresponding lanthanide complexes, with great potential impact for all aspects of lanthanide coordination.
- 23Peters, J. A.; Djanashvili, K.; Geraldes, C. F. G. C.; Platas-Iglesias, C. The Chemical Consequences of the Gradual Decrease of the Ionic Radius along the Ln-Series. Coord. Chem. Rev. 2020, 406, 213146 DOI: 10.1016/j.ccr.2019.213146Google Scholar23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXisVKqsbbL&md5=0238ed7d39ff1de80d1d36a3352a16e7The chemical consequences of the gradual decrease of the ionic radius along the Ln-seriesPeters, Joop A.; Djanashvili, Kristina; Geraldes, Carlos F. G. C.; Platas-Iglesias, CarlosCoordination Chemistry Reviews (2020), 406 (), 213146CODEN: CCHRAM; ISSN:0010-8545. (Elsevier B.V.)In the periodical system, the lanthanides (the 15 elements in the periodic table between barium and hafnium) are unique in the sense that their trivalent cations have their valence electrons hidden behind the 5s and 5p electrons. They show a gradual decrease in ionic radius with increasing at. no. (also known as the lanthanide contraction). The resulting steric effects det. to a large extent the geometries of complexes of these ions. Here, we discuss these effects, particularly upon the properties of the complexes in aq. soln., for selected families of Ln3+-complexes of oxycarboxylate and aminocarboxylate ligands. The phys. properties of the cations are very different, which is very useful for the elucidation of the configuration, conformation and the dynamics of the complexes by X-ray techniques, NMR spectroscopy, and optical techniques. Often the structural anal. is assisted by computational methods.
- 24Jordan, R. B. Lanthanide Contraction: What Is Normal?. Inorg. Chem. 2023, 62, 3715– 3721, DOI: 10.1021/acs.inorgchem.2c03674Google Scholar24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3sXjsF2lt7Y%253D&md5=7a8d5a6119851d88795feda850cdc1a2Lanthanide Contraction: What is Normal?Jordan, Robert B.Inorganic Chemistry (2023), 62 (9), 3715-3721CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)Renewed interest in lanthanide contraction results from its possible effect on the properties and applications of Ln(III) compds. and the theory related to these issues. To understand this effect, it is important to know what is a normal dependence of the contraction on the no. of 4f electrons, n. The normal trend is based on recent values of ionic radii that have a linear dependence on n for coordination nos. (CNs) of 6, 8, and 9. If the normal trend is not followed, then some other interactions in the system are affecting the extent of contraction. However, the suggestion that the variation is curved and fitted by a quadratic function has become popular in recent years. This report examines the Ln(III)-to-ligand atom distances for coordination compds. with CNs of 6-9 and the nitrides and phosphides. Least-squares fits to the linear and quadratic models are applied to all of the bond distances to det. when a quadratic model is justified. The result is that complex systems show a mixt. of linear and quadratic dependencies when individual bond distances are considered and that the linear model is most common and representative of the true lanthanide contraction.
- 25Bart, S. C. What Is the “Lanthanide Contraction”?. Inorg. Chem. 2023, 62, 3713– 3714, DOI: 10.1021/acs.inorgchem.3c00440Google Scholar25https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3sXjsF2lurk%253D&md5=fdd9d1aef33abb90594b76a1216fcc50What is the "Lanthanide Contraction"?Bart, Suzanne C.Inorganic Chemistry (2023), 62 (9), 3713-3714CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)There is no expanded citation for this reference.
- 26Fyfe, W. S. The Problem of Bond Type. Am. Mineral. 1954, 39, 991– 1004Google Scholar26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaG2MXotFeisg%253D%253D&md5=a3d8a1d9021b4583b8f77236ae4f7187The problem of bond typeFyfe, W. S.American Mineralogist (1954), 39 (), 991-1004CODEN: AMMIAY; ISSN:0003-004X.cf. C.A. 47, 11868g. Consideration of electronegativities is inadequate for quant. evaluation of the proportions of ionic and covalent bonding in a compd. The overlap integrals give better values, as illustrated for the alkali halides, and by comparison of Si-O and C-O bonds.
- 27Kawabe, I. Lanthanide Tetrad Effect in the Ln3+ Ionic Radii and Refined Spin-Pairing Energy Theory. Geochem. J. 1992, 26 (6), 309– 335, DOI: 10.2343/geochemj.26.309Google Scholar27https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXmsFKrt7c%253D&md5=7830517b8ce171b7305a975dee1a9317Lanthanide tetrad effect in the Ln3+ ionic radii and refined spin-pairing energy theoryKawabe, IwaoGeochemical Journal (1992), 26 (6), 309-35CODEN: GEJOBE; ISSN:0016-7002.The refined spin-pairing energy theory (RSPET) has been improved in order to understand quant. the tetrad or double-double effects recognized in the Ln3+ ionic radii. Since the ionic radii have been detd. from the lattice consts. and structural parameters of LnO1.5 and LnF3, the lattice energies of the compds. and the enthalpy difference of ΔHf°(LnF3) - ΔHf°(LnO1.5) have been examd. by the improved RSPET. The RSPET parameters for the lowest levels of 4fq electronic configurations strongly depend upon the effective nuclear charge (Z*). Such effects due to Z* have been taken into account. This made it possible to sep. the variations in the lattice energies and the enthalpy difference across the Ln3+ series into the following two parts: (1) the large variation as a smooth function of q (the lanthanide contraction trend), and (2) the small zig-zag variation referred to the tetrad or double-double effect. The lattice energy of LnO1.5 and ΔHf°(LnF3) - ΔHf°(LnO1.5) exhibit upward concave tetrad curves in their plots against q of Ln3+. The tetrad effect in the lattice energy of LnF3 is less conspicuous. This means that the Racah parameters for Ln3+ decrease very slightly in going from the gaseous free Ln3+ to LnF3, and then decrease greatly to LnO1.5, in accordance with the nephelauxetic series. The differences in Racah parameters between LnF3 and LnO1.5 have been estd. from ΔHf°(LnF3) - ΔHf°(LnO1.5) by means of an inversion technique based on the improved RSPET. The RSPET results for the thermochem. data are consistent with the careful spectroscopic detns. of Racah parameters for NdF3 and NdO1.5. Both the tetrad effect and the smooth lanthanide contraction seen in the Ln3+ ionic radii can be interpreted in terms of the quantum mech. energetics of 4f electrons.
- 28Gibbs, G. V.; Tamada, O.; Boisen, M. B., Jr. Atomic and Ionic Radii: A Comparison with Radii Derived from Electron Density Distributions. Phys. Chem. Miner. 1997, 24 (6), 432– 439, DOI: 10.1007/s002690050057Google Scholar28https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2sXltlaitrs%253D&md5=c155ab05be834f2dfee8af72a62c03c5Atomic and ionic radii: a comparison with radii derived from electron density distributionsGibbs, G. V.; Tamada, Osamu; Boisen, M. B., Jr.Physics and Chemistry of Minerals (1997), 24 (6), 432-439CODEN: PCMIDU; ISSN:0342-1791. (Springer)The bonded radii of anions obtained in topol. analyses of theor. and exptl. electron d. distributions differ from at., ionic and crystal radii in that oxide-, fluoride-, nitride- and sulfide-anion radii are not const. for a given coordination no. They vary in a regular way with bond length and the electronegativity of the cation to which they are bonded, exhibiting radii close to at. radii when bonded to a highly electroneg. cation and radii close to ionic radii when bonded to a highly electropos. cation. The electron d. distributions show that anions are not spherical but exhibit several different radii in different bonded directions. The bonded radii of cations correlate with ionic and at. radii. But unlike ionic radii, the bonded radius of a cation shows a relatively small increase in value with an increase in coordination no. In contrast to at. and ionic radii, the bonded radius of an ion in a crystal or mol. can be used as a reliable and well-defined est. of its radius in the direction of its bonds.
- 29Gibbs, G. V.; Ross, N. L.; Cox, D. F.; Rosso, K. M.; Iversen, B. B.; Spackman, M. A. Bonded Radii and the Contraction of the Electron Density of the Oxygen Atom by Bonded Interactions. J. Phys. Chem. A 2013, 117 (7), 1632– 1640, DOI: 10.1021/jp310462gGoogle Scholar29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXnvVGmsw%253D%253D&md5=d147f4dbd5d6d4ec63e980b51cc73dfcBonded Radii and the Contraction of the Electron Density of the Oxygen Atom by Bonded InteractionsGibbs, Gerald V.; Ross, Nancy L.; Cox, David F.; Rosso, Kevin M.; Iversen, Bo B.; Spackman, Mark A.Journal of Physical Chemistry A (2013), 117 (7), 1632-1640CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)The bonded radii for more than 700 bonded pairs of atoms, comprising more than 50 oxide crystals, extd. from exptl. and theor. electron d. distributions, are averaged and compared with the ionic radii for first, second, and third row atoms. At odds with the assumption of a fixed ionic radius of 1.40 Å for the oxide anion, the bonded radius for the anion, rb(O), decreases systematically from 1.40 to 0.65 Å as the electron d. distribution of the atom is progressively polarized and contracted by its bonded interactions. The radii for the more electropos. metal atoms agree with the ionic radii when the electron d. distribution of the anion is largely unpolarized by its bonded interactions. However, those for the more electroneg. metal atoms are progressively larger than the ionic radii as the electron d. distribution of the anion is progressively polarized and contracted along the bond vectors with decreasing bond length. The progressive decrease of rb(O) indicates that the compilation of sets of ionic radii, based on a fixed radius for the oxide anion, is problematic and impacts the accuracy of the ionic radii for the metal atoms. The assumption of a fixed radius for the anion, made in the derivation of sets of radii, not only results in unrealistic neg. ionic radii for the more electroneg. atoms but also in ionic radii that are as much as 0.5 Å smaller than the bonded radii, particularly for the more electroneg. M atoms. The lack of agreement between the ionic and the bonded radii for the more shared bonded interactions is ascribed to the progressive increase in the polarization and contraction of the electron d. of the oxide anion by the bonded interactions with a concomitant decrease in the radius of the anion, a factor that was largely neglected in the compilation of the ionic radii for fluoride, oxide, sulfide, and nitride crystals. The close agreement of the bonded radii and procrystal bonded radii is consistent with the argument that the chem. forces that govern the electron d. distributions and bonded radii are largely at. in nature, resulting in comparable electron d. distributions.
- 30Rahm, M.; Hoffmann, R.; Ashcroft, N. W. Atomic and Ionic Radii of Elements 1–96. Chem. – Eur. J. 2016, 22 (41), 14625– 14632, DOI: 10.1002/chem.201602949Google Scholar30https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtlyktbnP&md5=e2f480081daf268668503d6891189fc7Atomic and Ionic Radii of Elements 1-96Rahm, Martin; Hoffmann, Roald; Ashcroft, N. W.Chemistry - A European Journal (2016), 22 (41), 14625-14632CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Atomic and cationic radii have been calcd. for the first 96 elements, together with selected anionic radii. The metric adopted is the av. distance from the nucleus where the electron d. falls to 0.001 electrons per bohr3, following earlier work by Boyd. Our radii are derived using relativistic all-electron d. functional theory calcns., close to the basis set limit. They offer a systematic quant. measure of the sizes of non-interacting atoms, commonly invoked in the rationalization of chem. bonding, structure, and different properties. Remarkably, the at. radii as defined in this way correlate well with van der Waals radii derived from crystal structures. A rationalization for trends and exceptions in those correlations is provided.
- 31Liu, J.-B.; Schwarz, W. H. E.; Li, J. On Two Different Objectives of the Concepts of Ionic Radii. Chem. – Eur. J. 2013, 19 (44), 14758– 14767, DOI: 10.1002/chem.201300917Google Scholar31https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsF2nu7%252FO&md5=b6169c1ab18c468efce844b3ee904eb9On Two Different Objectives of the Concepts of Ionic RadiiLiu, Jian-Biao; Schwarz, W. H. Eugen; Li, JunChemistry - A European Journal (2013), 19 (44), 14758-14767CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Exptl. and theor. derived interat. distances (D) and ionic radii (R) of more than a hundred monomeric (AX), dimeric (A2X2, ABXY), and cryst. ([AX]) alkali halide species (A=Li, Na, K, Rb, Cs, Fr; X=H, F, Cl, Br, I, At) have been analyzed. Chemists use the word "at. radius" for two antithetic concepts. Let DCiEE'jj' be the "billion" of distances i between two adjacent atoms in the millions of known compds. C from a hundred different elements E in bonding states j. The common chem. aim is partitioning D approx. into increments REj + RE'j'. This can be achieved with a few (say <thousand) predictive consts. REj. An antipodal aim is specifying in hindsight an electron d. feature in the "billion" of different bonds i, by partitioning them into "two billions" of exact bonded radii RECi + RE'Ci. The const. incremental and the variable bonded radii concepts with the same generic name are useful in different fields of research. Different concepts should be well distinguished, since they have different meaning, different numerical values, and different purposes.
- 32Cordero, B.; Gómez, V.; Platero-Prats, A. E.; Revés, M.; Echeverría, J.; Cremades, E.; Barragán, F.; Alvarez, S. Covalent Radii Revisited. Dalton Trans. 2008, 21, 2832– 2838, DOI: 10.1039/b801115jGoogle ScholarThere is no corresponding record for this reference.
- 33Pyykkö, P.; Atsumi, M. Molecular Single-Bond Covalent Radii for Elements 1–118. Chem. – Eur. J. 2009, 15 (1), 186– 197, DOI: 10.1002/chem.200800987Google ScholarThere is no corresponding record for this reference.
- 34Pyykkö, P. Additive Covalent Radii for Single-, Double-, and Triple-Bonded Molecules and Tetrahedrally Bonded Crystals: A Summary. J. Phys. Chem. A 2015, 119 (11), 2326– 2337, DOI: 10.1021/jp5065819Google Scholar34https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhsVektrzI&md5=6c1fec0c71e630c9c87aee775ce8ca9eAdditive Covalent Radii for Single-, Double-, and Triple-Bonded Molecules and Tetrahedrally Bonded Crystals: A SummaryPyykko, PekkaJournal of Physical Chemistry A (2015), 119 (11), 2326-2337CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)A review. The recent fits of additive covalent radii RAB = rA + rB for the title systems are reviewed and compared with alternative systems of radii by other authors or with further exptl. data. The agreement of the predicted R with expt. is good, provided that the A-B bond is not too ionic, or the coordination nos. of the two atoms too different from the original input data, used in the fit. Bonds between transition metals and halides are not included in the single-bond set, because of their partial multiple-bond character.
- 35Gunnlaugsson, T.; Leonard, J. P.; Mulready, S.; Nieuwenhuyzen, M. Three Step vs One Pot Synthesis and X-Ray Crystallographic Investigation of Heptadentate Triamide Cyclen (1,4,7,10-Tetraazacyclododecane) Based Ligands and Some of Their Lanthanide Ion Complexes. Tetrahedron 2004, 60 (1), 105– 113, DOI: 10.1016/j.tet.2003.10.086Google Scholar35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXpslOjtLg%253D&md5=bf5dff38e1edf05f8d23cbb11b72d1c6Three step vs. one pot synthesis and X-ray crystallographic investigation of heptadentate triamide cyclen (1,4,7,10-tetraazacyclododecane) based ligands and some of their lanthanide ion complexesGunnlaugsson, Thorfinnur; Leonard, Joseph P.; Mulready, Sinead; Nieuwenhuyzen, MarkTetrahedron (2004), 60 (1), 105-113CODEN: TETRAB; ISSN:0040-4020. (Elsevier Science B.V.)The synthesis of several lanthanide complexes from the tris alkylated cyclen (1,4,7,10-tetraazacyclododecane) ligands (I, R = Me, 1;R = H, 2) is described. The prepn. of 1 and 2 were studied by two different synthetic routes (Methods 1 and 2). The 1st of these involves the mono protection of cyclen using 4-methoxyphenylsulfonyl chloride, followed by alkylation of the remaining three secondary amines of cyclen, and deprotection using solvated Na(s). Using this approach only 1 was successfully formed. The x-ray crystal structure of the intermediate, (II = 9) and the corresponding La(III) complex, 9·La is presented. The 2nd method involved the direct synthesis of the two ligands in a single step. The x-ray crystallog. of the Eu(III) complex of one of these ligands is presented. Whereas, Method 1 yielded the product 1 in high purity, but in low overall yield, Method 2 gave higher yields for both ligands (∼50% for both).
- 36Amin, S.; Morrow, J. R.; Lake, C. H.; Churchill, M. R. Lanthanide(III) Tetraamide Macrocyclic Complexes as Synthetic Ribonucleases: Structure and Catalytic Properties of[La(Tcmc)(CF3SO3)(EtOH)](CF3SO3)2. Angew. Chem., Int. Ed. 1994, 33 (7), 773– 775, DOI: 10.1002/anie.199407731Google ScholarThere is no corresponding record for this reference.
- 37Franklin, S. J.; Raymond, K. N. Solution Structure and Dynamics of Lanthanide Complexes of the Macrocyclic Polyamino Carboxylate DTPA-Dien. NMR Study and Crystal Structures of the Lanthanum(III) and Europium(III) Complexes. Inorg. Chem. 1994, 33 (25), 5794– 5804, DOI: 10.1021/ic00103a029Google Scholar37https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXntFCnurk%253D&md5=1482406696ff4ac0c56f722b8f5c6209Solution Structure and Dynamics of Lanthanide Complexes of the Macrocyclic Polyamino Carboxylate DTPA-dien. NMR Study and Crystal Structures of the Lanthanum(III) and Europium(III) ComplexesFranklin, Sonya J.; Raymond, Kenneth N.Inorganic Chemistry (1994), 33 (25), 5794-804CODEN: INOCAJ; ISSN:0020-1669.An 18-membered macrocyclic DTPA-bis(amide) ligand (I; DTPA = diethylenetriaminepentaacetic acid) contg. a heteroatom in the amide link was prepd. via the condensation of DTPA-dianhydride and diethylenetriamine. The soln. structures of the two isomeric pairs present in the Ln(III) complexes of DTPA-dien were studied by 1H NMR. One enantiomeric pair exhibits slow exchange on the NMR time scale at low temps. (0-25°) and dynamic behavior at higher temps. The other isomeric pair exhibits an unusual static behavior; exchange remains slow even at 95°. Peak assignments for the Eu(DTPA-dien) spectra are given based on deuteration studies, 2-dimensional COSY spectroscopy, and 2-dimensional EXSY spectroscopy. 2D EXSY spectroscopy at several temps. and mixing times showed that ΔG⧧299 for the dynamic isomerization is 57.5 ± 0.3 kJ/mol, and that the dynamic isomer is an intermediate for the static isomerization, which occurs with a change in backbone amine chirality. The structures of the La(III) and Eu(III) DTPA-dien complexes were detd. by x-ray anal. [La(DTPA-dienH+)H2O]2(CF3SO3-)2·18H2O crystallizes as a carboxylate-bridged dimer about a center of inversion in the orthorhombic space group Pbca with a 12.626(2), b 21.405(3), c 26.422(9) Å, and Z = 8. Each La ion is 11-coordinate with octadentate ligand coordination, an η2 bridging carboxylate, and one H2O. [Eu(DTPA-dienH+)]4(CF3SO3-)4·6NaCF3SO3·20H2O crystallizes as a carboxylate-bridged tetramer with two crystallog. independent Eu(III) positions (Z = 8 for each) in the monoclinic space group C2/c: a 30.94(1), b 23.456(3), c 22.611(4) Å, β 105.78(2)°. The coordination geometries about Eu1 and Eu2 are nearly identical and are described as a nine-coordinate tricapped trigonal prism with octadentate ligand coordination plus an η1 bridging carboxylate. The tendency to oligomerize is attributed to the constraints imposed by the macrocycle and the H bonding available with the link heteroatom. The structural differences between the two complexes are attributed to a difference in La(III) and Eu(III) ionic size. The soln. structure of the dynamic isomer is the same as the monomer unit of the crystal structures, and the static isomer is similar, save for a change in one terminal backbone nitrogens' chirality.
- 38Nakai, H.; Nonaka, K.; Goto, T.; Seo, J.; Matsumoto, T.; Ogo, S. A Macrocyclic Tetraamine Bearing Four Phenol Groups: A New Class of Heptadentate Ligands to Provide an Oxygen-Sensitive Luminescent Tb(iii) Complex with an Extendable Phenol Pendant Arm. Dalton Trans. 2015, 44 (24), 10923– 10927, DOI: 10.1039/C5DT00816FGoogle Scholar38https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXnvFWguro%253D&md5=12d6f49a8c5eb0f1586e6ba37dc2af91A macrocyclic tetraamine bearing four phenol groups: a new class of heptadentate ligands to provide an oxygen-sensitive luminescent Tb(III) complex with an extendable phenol pendant armNakai, Hidetaka; Nonaka, Kyoshiro; Goto, Takahiro; Seo, Juncheol; Matsumoto, Takahiro; Ogo, SeijiDalton Transactions (2015), 44 (24), 10923-10927CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)This paper presents a 1,4,7,10-teraazacyclododecane-based tetrakis-phenol (H4L) as a protonated ligand precursor and its oxygen-sensitive luminescent terbium(III) complex with an extendable phenol pendant arm (Φ = 0.91 under N2, Φ = 0.031 under air), in which the potentially N4O4-octadentate ligand unprecedentedly coordinates to the Tb3+ ion in a N4O3-heptadentate fashion (1, TbL).
- 39Wen, H.-R.; Zhang, J.-L.; Liang, F.-Y.; Yang, K.; Liu, S.-J.; Liu, C.-M. Multifunctional Lanthanide Complexes Based on Tetraazacyclolamidophenol Ligand with Field-Induced Slow Magnetic Relaxation, Luminescent and SHG Properties: Multifunctional Lanthanide Complexes Based on Tetraazacyclolamidophenol Ligand with Field-Induced Slow Magnetic Relaxation, Luminescent and SHG Proper. Eur. J. Inorg. Chem. 2019, 2019 (10), 1406– 1412, DOI: 10.1002/ejic.201801492Google Scholar39https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXjvFWgu7Y%253D&md5=ab1bfc71f75d61bb6b4b00adc391323fMultifunctional Lanthanide Complexes Based on Tetraazacyclolamidophenol Ligand with Field-Induced Slow Magnetic Relaxation, Luminescent and SHG PropertiesWen, He-Rui; Zhang, Jia-Li; Liang, Fu-Yong; Yang, Kai; Liu, Sui-Jun; Liu, Cai-MingEuropean Journal of Inorganic Chemistry (2019), 2019 (10), 1406-1412CODEN: EJICFO; ISSN:1434-1948. (Wiley-VCH Verlag GmbH & Co. KGaA)Two multifunctional lanthanide complexes, [Dy(HL)]·MeOH (1) and [Er(HL)]·MeOH (2), [H4L = N,N',N'',N'''-tetra(3,5-dimethyl-2-Hydroxybenzyl)-1,4,7,10-tetraazacyclododecane] were synthesized and structurally characterized. Complexes 1 and 2 are isomorphic and crystallize in the noncentrosym. orthorhombic space group Pca21. Their structure consists of one seven-coordinated LnIII ion with the coordination geometry of trigonal prism, one HL3- ligand and one lattice MeOH mol. They exhibit 2nd-harmonic generation (SHG) effect. Complex 1 displays strong fluorescent emissions, which are typical narrow emission bands of lanthanide ions. Complex 1 features field-induced slow magnetic relaxation behavior. Therefore, complex 1 may be a potential multifunctional mol. material.
- 40Urbanovský, P.; Kotek, J.; Císařová, I.; Hermann, P. The Solid-State Structures and Ligand Cavity Evaluation of Lanthanide(III) Complexes of a DOTA Analogue with a (Dibenzylamino)Methylphosphinate Pendant Arm. Dalton Trans. 2020, 49 (5), 1555– 1569, DOI: 10.1039/C9DT04056KGoogle Scholar40https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitleju7zJ&md5=58cf71adce2c996b34b6c6c6e7dbfdb5The solid-state structures and ligand cavity evaluation of lanthanide(III) complexes of a DOTA analogue with a (dibenzylamino)methylphosphinate pendant armUrbanovsky, Peter; Kotek, Jan; Cisarova, Ivana; Hermann, PetrDalton Transactions (2020), 49 (5), 1555-1569CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)A series of lanthanide(III) complexes of a monophosphinate analog of H4dota, 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic-10-methyl[(N,N-dibenzylamino)methyl]phosphinic acid (H4do3apDBAm = H4L1), were prepd. and their solid-state structures were studied using single-crystal X-ray diffraction. In all structures, the ligand anion was octadentately coordinated to the Ln(III) or Sc(III) ions similarly to other DOTA-like ligands, i.e. forming parallel N4- and O4-planes. The lighter lanthanide(III) complexes (till dysprosium) were nonacoordinated in the twisted square-antiprismatic (TSA) configuration with the apical coordination of water mols. or oxygen atoms from the neighboring complex unit. The heavier lanthanide(III) complexes (from terbium) were found as the "anhyd." octacoordinated twisted square-antiprismatic (TSA') isomer. For the terbium(III) ion, both forms were structurally characterized. The structural data of the Ln(III)-H4L1 complexes and complexes of several related DOTA-like ligands were analyzed. It clearly showed that the structural parameters for the square-antiprismatic (SA) isomers were clustered in a small range while those for the TSA/TSA' isomers were significantly more spread. The anal. also gave useful information about the influence of various pendant arms on the structure of the complexes of the DOTA-like ligands. The twist angle (torsion) of the chelate ring contg. a larger phosphorus atom was similar to those of the remaining three acetate pendants. It led to a larger sepn. of the N4···O4 planes and to smaller trans-O-Ln-O angles than the parameters found in the complexes of H4dota and its tetraamide derivs. dotam(R). It resulted in a relatively long bond between the metal ion and the coordinated water mol. It led, together with the neg. charge of the oxygen atoms forming the O4-plane, to an extremely fast water exchange rate reported for the Gd(III)-H4L1 complex and, generally, to a fast water exchange of Gd(III) complexes with the monophosphorus acid analogs of H4dota, H5do3ap/H4do3apR.
- 41Woods, M.; Payne, K. M.; Valente, E. J.; Kucera, B. E.; Young, V. G. Crystal Structures of DOTMA Chelates from Ce3+ to Yb3+: Evidence for a Continuum of Metal Ion Hydration States. Chem. – Eur. J. 2019, 25 (42), 9997– 10005, DOI: 10.1002/chem.201902068Google Scholar41https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtlaqtLfJ&md5=a9926b84e88d9e64a38fd241d90ffabcCrystal Structures of DOTMA Chelates from Ce3+ to Yb3+: Evidence for a Continuum of Metal Ion Hydration StatesWoods, Mark; Payne, Katherine M.; Valente, Edward J.; Kucera, Benjamin E.; Young, Victor G. Jr.Chemistry - A European Journal (2019), 25 (42), 9997-10005CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)The crystal structures of chelates formed between each stable paramagnetic lanthanide ion and the octadentate polyamino carboxylate ligand DOTMA are described. A total of 23 individual chelates structures were obtained; in each chelate the coordination geometry around the metal ion is best described as a twisted square antiprism (torsion angle -25.0°--31.4°). Despite the uniformity of the general coordination geometry provided by the DOTMA ligand, there is a considerable variation in the hydration state of each chelate. The early Ln3+ chelates are assocd. with a single inner sphere water mol.; the Ln-OH2 interaction is remarkable for being very long. After a clear break at gadolinium, the no. of chelates in the unit cell that have a water mol. interacting with the Ln3+ decreases linearly until at Tm3+ no water is found to interact with the metal ion. The Ln-OH2 distance obsd. in the chelates of the later Ln3+ ions are also extremely long and increase as the ions contract (2.550-2.732 Å). No clear break between hydrated and dehydrated chelates is obsd.; rather this series of chelates appear to represent a continuum of hydration states in which the ligand gradually closes around the metal ion as its ionic radius decreases (with decreased hydration) and the metal drops down into the coordination cage.
- 42Starynowicz, P. Complexes of Divalent Europium with Dotp and Dotpph. New J. Chem. 2021, 45 (13), 5879– 5889, DOI: 10.1039/D1NJ00393CGoogle Scholar42https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXltlegurw%253D&md5=3b02b9aa7253fd7168d0a9b84964056fComplexes of divalent europium with dotp and dotpphStarynowicz, PrzemyslawNew Journal of Chemistry (2021), 45 (13), 5879-5889CODEN: NJCHE5; ISSN:1144-0546. (Royal Society of Chemistry)Two complexes of divalent europium, with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylene phosphonate) (dotp) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylene P-phenylphosphinate) (dotpph), were obtained by electrochem. synthesis. In both compds., the Eu2+ cation is 8-coordinate, surrounded by 4 oxygen atoms from phosphonate or phosphinate groups and 4 nitrogen atoms. The complex with dotp shows green luminescence at 77 K, while in the dotpph complex the emission is almost completely quenched. The TD DFT calcns. suggest that in both complexes the emission is of anomalous character: s → f for the first complex and π* → f for the other. Polarog. half-wave potentials of both complexes are similar to those of Eu aminopolycarboxylates. The Eu-O bonds, analyzed using topol. methods, are ionic; the Eu-N bonds in the first complex show a certain degree of covalency, while in the other one they are ionic.
- 43Basal, L. A.; Bailey, M. D.; Romero, J.; Ali, M. M.; Kurenbekova, L.; Yustein, J.; Pautler, R. G.; Allen, M. J. Fluorinated EuII -Based Multimodal Contrast Agent for Temperature- and Redox-Responsive Magnetic Resonance Imaging. Chem. Sci. 2017, 8 (12), 8345– 8350, DOI: 10.1039/C7SC03142DGoogle Scholar43https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhslantLvJ&md5=1dfe4497908d97d5a81bcc698185b607Fluorinated EuII-based multimodal contrast agent for temperature- and redox-responsive magnetic resonance imagingBasal, Lina A.; Bailey, Matthew D.; Romero, Jonathan; Ali, Meser M.; Kurenbekova, Lyazat; Yustein, Jason; Pautler, Robia G.; Allen, Matthew J.Chemical Science (2017), 8 (12), 8345-8350CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)Magnetic resonance imaging (MRI) using redox-active, EuII-contg. complexes is one of the most promising techniques for noninvasively imaging hypoxia in vivo. In this technique, pos. (T1-weighted) contrast enhancement persists in areas of relatively low oxidizing ability, such as hypoxic tissue. Herein, we describe a fluorinated, EuII-contg. complex in which the redox-active metal is caged by intramol. interactions. The position of the fluorine atoms enables temp.-responsive contrast enhancement in the reduced form of the contrast agent and detection of the oxidized contrast agent via MRI in vivo. Pos. contrast is obsd. in 1H-MRI with Eu in the +2 oxidn. state, and chem. exchange satn. transfer and 19F-MRI signal are obsd. with Eu in the +3 oxidn. state. Contrast enhancement is controlled by the redox state of Eu, and modulated by the fluorous interactions that cage a bound water mol. reduce relaxivity in a temp.-dependent fashion. Together, these advancements constitute the first report of in vivo, redox-responsive imaging using 19F-MRI.
- 44Burai, L.; Tóth, É.; Seibig, S.; Scopelliti, R.; Merbach, A. E. Solution and Solid-State Characterization of EuII Chelates: A Possible Route Towards Redox Responsive MRI Contrast Agents. Chem. – Eur. J. 2000, 6 (20), 3761– 3770, DOI: 10.1002/1521-3765(20001016)6:20<3761::AID-CHEM3761>3.0.CO;2-6Google Scholar44https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXns1Cmu7c%253D&md5=8da82fdac83df748b26a5d45c31b9872Solution and solid-state characterization of EuII chelates: a possible route towards redox responsive MRI contrast agentsBurai, Laszlo; Toth, Eva; Seibig, Sabine; Scopelliti, Rosario; Merbach, Andre E.Chemistry - A European Journal (2000), 6 (20), 3761-3770CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH)We report the first solid state X-ray crystal structure for a EuII chelate, [C(NH2)3]3[EuII(DTPA)(H2O)]·8H2O, in comparison with those for the corresponding Sr analog, [C(NH2)3]3[Sr(DTPA)(H2O)]·8H2O and for [Sr(ODDA)]·8H2O (DTPA5- = diethylenetriamine-N,N,N',N",N"-pentaacetate, ODDA2- = 1,4,10,13-tetraoxa-7,16-diaza-cyclooctadecane-7,16-diacetate). The two DTPA complexes are isostructural due to the similar ionic size and charge of Sr2+ and Eu2+. The redox stability of [EuII(ODDA)(H2O)] and [EuII(ODDM)]2- complexes has been investigated by cyclovoltammetry and UV/Vis spectrophotometry (ODDM4- = 1,4,10,13-tetraoxa-7,16-diaza-cyclooctadecane-7,16-dimalonate). The macrocyclic complexes are much more stable against oxidn. than [EuII(DTPA)(H2O)]3- (the redox potentials are E1/2 = -0.82 V, -0.92 V, and -1.35 V vs. Ag/AgCl electrode for [EuIII/II(ODDA)(H2O)], [EuIII/II(ODDM)], and [EuIII/II(DTPA)(H2O)], resp., compared with -0.63 V for EuIII/II aqua). The thermodn. stability consts. of [EuII(ODDA)(H2O)], [EuII(ODDM)]2-, [Sr(ODDA)(H2O)], and [Sr(ODDM)]2- were also detd. by pH potentiometry. They are slightly higher for the EuII complexes than those for the corresponding Sr analogs (logKML = 9.85, 13.07, 8.66, and 11.34 for [EuII(ODDA)(H2O)], [EuII(ODDM)]2-, [Sr(ODDA)(H2O)], and [Sr(ODDM)]2-, resp., 0.1 M (CH3)4NCl). The increased thermodn. and redox stability of the EuII complex formed with ODDA as compared with the traditional ligand DTPA can be of importance when biomedical application is concerned. A variable-temp. 17O-NMR and 1H-nuclear magnetic relaxation dispersion (NMRD) study has been performed on [EuII(ODDA)(H2O)] and [EuII(ODDM)]2- in aq. soln. [EuII(ODDM)]2- has no inner-sphere water mol. which allowed us to use it as an outer-sphere model for [EuII(ODDA)(H2O)]. The water exchange rate (kex298 = 0.43 × 109 s-1) is one third of that obtained for [EuII(DTPA)(H2O)]3-. The variable pressure 17O-NMR study yielded a neg. activation vol., Δν = -3.9 cm3mol-1; this indicates associatively activated water exchange. This water exchange rate is in the optimal range to attain max. proton relaxivities, which are, however, strongly limited by the fast rotation of the small mol. wt. complex.
- 45Dovrat, G.; Pevzner, S.; Maimon, E.; Vainer, R.; Iliashevsky, O.; Ben-Eliyahu, Y.; Moisy, P.; Bettelheim, A.; Zilbermann, I. DOTP versus DOTA as Ligands for Lanthanide Cations: Novel Structurally Characterized CeIV and CeIII Cyclen-Based Complexes and Clusters in Aqueous Solutions. Chem. – Eur. J. 2022, 28 (61), e20221868 DOI: 10.1002/chem.202201868Google ScholarThere is no corresponding record for this reference.
- 46Rodríguez-Rodríguez, A.; Regueiro-Figueroa, M.; Esteban-Gómez, D.; Rodríguez-Blas, T.; Patinec, V.; Tripier, R.; Tircsó, G.; Carniato, F.; Botta, M.; Platas-Iglesias, C. Definition of the Labile Capping Bond Effect in Lanthanide Complexes. Chem. – Eur. J. 2017, 23 (5), 1110– 1117, DOI: 10.1002/chem.201604390Google Scholar46https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitFahs73O&md5=2a8dab208430d2d7386be1931eb5a126Definition of the Labile Capping Bond Effect in Lanthanide ComplexesRodriguez-Rodriguez, Aurora; Regueiro-Figueroa, Martin; Esteban-Gomez, David; Rodriguez-Blas, Teresa; Patinec, Veronique; Tripier, Raphael; Tircso, Gyula; Carniato, Fabio; Botta, Mauro; Platas-Iglesias, CarlosChemistry - A European Journal (2017), 23 (5), 1110-1117CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Two macrocyclic ligands contg. a cyclen unit, a Me group, a picolinate arm, and two acetate pendant arms attached to two nitrogen atoms of the macrocycle either in trans (1,7-H3Medo2 ampa = 2,2'-(7-((6-carboxypyridin-2-yl)methyl)-10-methyl-1,4,7,10-tetraazacyclododecane-1,4-diyl)diacetic acid) or in cis (1,4-H3Medo2 ampa) positions are reported. These ligands provide eight-coordination to the Ln3+ ions, leaving a coordination position available for a water mol. that occupies a capping position in the twisted square antiprismatic polyhedron (1,4-H3Medo2 ampa) or one of the positions of the square antiprism (1,7-H3Medo2 ampa). The charge neutral [Gd(1,7-Medo2 ampa)] complex presents an unprecedentedly low water-exchange rate (kex298=8.8 × 103 s-1), whereas water exchange in [Gd(1,4-Medo2 ampa)] is three orders of magnitude faster (kex298=6.6 × 106 s-1). These results showcase the labile capping bond phenomenon: A ligand occupying a capping position is hindered by the environment and thus is intrinsically labile.
- 47Caravan, P.; Esteban-Gómez, D.; Rodríguez-Rodríguez, A.; Platas-Iglesias, C. Water Exchange in Lanthanide Complexes for MRI Applications. Lessons Learned over the Last 25 Years. Dalton Trans. 2019, 48 (30), 11161– 11180, DOI: 10.1039/C9DT01948KGoogle Scholar47https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtF2nt7fF&md5=02e06253fa7c2f3ca51f0a3dfd289f65Water exchange in lanthanide complexes for MRI applications. Lessons learned over the last 25 yearsCaravan, Peter; Esteban-Gomez, David; Rodriguez-Rodriguez, Aurora; Platas-Iglesias, CarlosDalton Transactions (2019), 48 (30), 11161-11180CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)The water exchange rates of water mols. coordinated to the metal ion in lanthanide complexes have been profusely investigated during the last 25 years, esp. in the case of Gd3+ and Eu3+ complexes. This is mainly related to the important application of some Gd3+ complexes as contrast agents in magnetic resonance imaging (MRI), and the intensive investigation of Eu3+ complexes as contrast agent candidates providing contrast through the chem. exchange satn. transfer mechanism (CEST). Both applications require a fine tunning of the exchange rate of the coordinated water mol. to yield optimal response. Herein we review the progress made in this field to control water exchange in a rational way through ligand design, providing relationships between the obsd. trends, the structures of the complexes and the mechanisms responsible for the water exchange reaction.
- 48Garda, Z.; Nagy, V.; Rodríguez-Rodríguez, A.; Pujales-Paradela, R.; Patinec, V.; Angelovski, G.; Tóth, É.; Kálmán, F. K.; Esteban-Gómez, D.; Tripier, R.; Platas-Iglesias, C.; Tircsó, G. Unexpected Trends in the Stability and Dissociation Kinetics of Lanthanide(III) Complexes with Cyclen-Based Ligands across the Lanthanide Series. Inorg. Chem. 2020, 59 (12), 8184– 8195, DOI: 10.1021/acs.inorgchem.0c00520Google Scholar48https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXot1eitbY%253D&md5=76f902afc753ddb3a6ada1d5c8385553Unexpected Trends in the Stability and Dissociation Kinetics of Lanthanide(III) Complexes with Cycle-Based Ligands across the Lanthanide SeriesGarda, Zoltan; Nagy, Viktoria; Rodriguez-Rodriguez, Aurora; Pujales-Paradela, Rosa; Patinec, Veronique; Angelovski, Goran; Toth, Eva; Kalman, Ferenc K.; Esteban-Gomez, David; Tripier, Raphael; Platas-Iglesias, Carlos; Tircso, GyulaInorganic Chemistry (2020), 59 (12), 8184-8195CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)We report a detailed study of the thermodn. stability and dissocn. kinetics of lanthanide complexes with two ligands contg. a cyclen unit, a Me group, a picolinate arm, and two acetate pendant arms linked to two nitrogen atoms of the macrocycle in either cis (1,4-H3DO2APA) or trans (1,7-H3DO2APA) positions. The stability consts. of the Gd3+ complexes with these two ligands are very similar, with log KGdL values of 16.98 and 16.33 for the complexes of 1,4-H3DO2APA and 1,7-H3DO2APA, resp. The stability consts. of complexes with 1,4-H3DO2APA follow the usual trend, increasing from log KLaL = 15.96 to log KLuL = 19.21. However, the stability of [Ln(1,7-DO2APA)] complexes decreases from log K = 16.33 for Gd3+ to 14.24 for Lu3+. The acid-catalyzed dissocn. rates of the Gd3+ complexes differ by a factor of ∼ 15, with rate consts. (k1) of 1.42 and 23.5 M-1 s-1 for [Gd(1,4-DO2APA)] and [Gd(1,7-DO2APA)], resp. This difference is magnified across the lanthanide series to reach a 5 orders of magnitude higher k1 for [Yb(1,7-DO2APA)] (1475 M-1 s-1) than for [Yb(1,4-DO2APA)] (5.79 x 10-3 M-1 s-1). The acid-catalyzed mechanism involves the protonation of a carboxylate group, followed by a cascade of proton-transfer events that result in the protonation of a nitrogen atom of the cyclen unit. D. functional theory calcns. suggest a correlation between the strength of the Ln-Ocarboxylate bonds and the kinetic inertness of the complex, with stronger bonds providing more inert complexes. The 1H NMR resonance of the coordinated water mol. in the [Yb(1,7-DO2APA)] complex at 176 ppm provides a sizable chem. exchange satn. transfer effect thanks to a slow water exchange rate of (15.9 ± 1.6) x 103 s-1. The arrangement of the ligand donor atoms around the lanthanide ion provokes dramatic differences in the thermodn. stabilities and dissocn. kinetics of lanthanide complexes, as demonstrated by investigating the complexes with two isomeric cyclen-based ligands, contg. a picolinate arm and two acetate arms in either positions 1,7 or 1,4 of the macrocyclic structure.
- 49Jannin, S.; Helm, L.; Bodenhausen, G. Kinetics of Yttrium–Ligand Complexation Monitored Using Hyperpolarized 89 Y as a Model for Gadolinium in Contrast Agents. J. Am. Chem. Soc. 2010, 132 (14), 5006– 5007, DOI: 10.1021/ja1013954Google Scholar49https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXjs1Wrsr4%253D&md5=0aa927480b82bc175a938ab9ca7eaabaKinetics of Yttrium-Ligand Complexation Monitored Using Hyperpolarized 89Y as a Model for Gadolinium in Contrast AgentsMieville, Pascal; Jannin, Sami; Helm, Lothar; Bodenhausen, GeoffreyJournal of the American Chemical Society (2010), 132 (14), 5006-5007CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Hyperpolarization by dissoln. dynamic nuclear polarization (DNP) enhances 89Y spin magnetization by 3 to 4 orders of magnitude and provides a way to monitor yttrium-ligand complexation "on the fly" by means of 89Y NMR. In this communication, we show an example of free yttrium Y3+ being complexed with 1,4,7,10-tetrakis(acetamido)-1,4,7,10-tetraazacyclododecane (DOTAM) to form [Y(DOTAM)(H2O)]3+ as a model for gadolinium in contrast agents.
- 50Tickner, B. J.; Stasiuk, G. J.; Duckett, S. B.; Angelovski, G. The Use of Yttrium in Medical Imaging and Therapy: Historical Background and Future Perspectives. Chem. Soc. Rev. 2020, 49 (17), 6169– 6185, DOI: 10.1039/C9CS00840CGoogle Scholar50https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB38jmtVynuw%253D%253D&md5=6abc5c18a5813e7bb6df74d2c8cd8714The use of yttrium in medical imaging and therapy: historical background and future perspectivesTickner Ben J; Stasiuk Graeme J; Duckett Simon B; Angelovski GoranChemical Society reviews (2020), 49 (17), 6169-6185 ISSN:.Yttrium is a chemically versatile rare earth element that finds use in a range of applications including lasers and superconductors. In medicine, yttrium-based materials are used in medical lasers and biomedical implants. This is extended through the array of available yttrium isotopes to enable roles for (90)Y complexes as radiopharmaceuticals and (86)Y tracers for positron emission tomography (PET) imaging. The naturally abundant isotope (89)Y is proving to be suitable for nuclear magnetic resonance investigations, where initial reports in the emerging field of hyperpolarised magnetic resonance imaging (MRI) are promising. In this review we explore the coordination and radiochemical properties of yttrium, and its role in drugs for radiotherapy, PET imaging agents and perspectives for applications in hyperpolarised MRI.
- 51Vaughn, B. A.; Koller, A. J.; Chen, Z.; Ahn, S. H.; Loveless, C. S.; Cingoranelli, S. J.; Yang, Y.; Cirri, A.; Johnson, C. J.; Lapi, S. E.; Chapman, K. W.; Boros, E. Homologous Structural, Chemical, and Biological Behavior of Sc and Lu Complexes of the Picaga Bifunctional Chelator: Toward Development of Matched Theranostic Pairs for Radiopharmaceutical Applications. Bioconjugate Chem. 2021, 32 (7), 1232– 1241, DOI: 10.1021/acs.bioconjchem.0c00574Google Scholar51https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisVyiu7rN&md5=5bca186810cf291bf588946144fc4ca2Homologous Structural, Chemical, and Biological Behavior of Sc and Lu Complexes of the Picaga Bifunctional Chelator: Toward Development of Matched Theranostic Pairs for Radiopharmaceutical ApplicationsVaughn, Brett A.; Koller, Angus J.; Chen, Zhihengyu; Ahn, Shin Hye; Loveless, C. Shaun; Cingoranelli, Shelbie J.; Yang, Yi; Cirri, Anthony; Johnson, Christopher J.; Lapi, Suzanne E.; Chapman, Karena W.; Boros, EszterBioconjugate Chemistry (2021), 32 (7), 1232-1241CODEN: BCCHES; ISSN:1043-1802. (American Chemical Society)The radioactive isotopes scandium-44/47 and lutetium-177 are gaining relevance for radioimaging and radiotherapy, resulting in a surge of studies on their coordination chem. and subsequent applications. Although the trivalent ions of these elements are considered close homologues, dissimilar chem. behavior is obsd. when they are complexed by large ligand architectures due to discrepancies between Lu(III) and Sc(III) ions with respect to size, chem. hardness, and Lewis acidity. Here, authors demonstrate that Lu and Sc complexes of 1,4-bis(methoxycarbonyl)-7-[(6-carboxypyridin-2-yl)methyl]-1,4,7-triazacyclononane (H3mpatcn) and its corresponding bioconjugate picaga-DUPA can be employed to promote analogous structural features and, subsequently, biol. properties for coordination complexes of these ions. The close homol. was evidenced using potentiometric methods, computational modeling, variable temp. mass spectrometry, and pair distribution function anal. of x-ray scattering data. Radiochem. labeling, in vitro stability, and biodistribution studies with Sc-47 and Lu-177 indicate that the 7-coordinate ligand environment of the bifunctional picaga ligand is compatible with biol. applications and the future investigation of β-emitting, picaga-chelated Sc and Lu isotopes for radiotherapy.
- 52Caravan, P.; Ellison, J. J.; McMurry, T. J.; Lauffer, R. B. Gadolinium(III) Chelates as MRI Contrast Agents: Structure, Dynamics, and Applications. Chem. Rev. 1999, 99 (9), 2293– 2352, DOI: 10.1021/cr980440xGoogle Scholar52https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXlt12rsrg%253D&md5=10b76764c56cadb0b2426c6bdf01506bGadolinium(III) Chelates as MRI Contrast Agents: Structure, Dynamics, and ApplicationsCaravan, Peter; Ellison, Jeffrey J.; McMurry, Thomas J.; Lauffer, Randall B.Chemical Reviews (Washington, D. C.) (1999), 99 (9), 2293-2352CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review with 343 refs. on gadolinium(III) chelates judged to be of sufficient stability for in vivo use. Topics covered include soln. and solid state structures, relaxation theory, phys. properties, and macromol. conjugates.
- 53Le Fur, M.; Molnár, E.; Beyler, M.; Kálmán, F. K.; Fougère, O.; Esteban-Gómez, D.; Rousseaux, O.; Tripier, R.; Tircsó, G.; Platas-Iglesias, C. A Coordination Chemistry Approach to Fine-Tune the Physicochemical Parameters of Lanthanide Complexes Relevant to Medical Applications. Chem. – Eur. J. 2018, 24 (13), 3127– 3131, DOI: 10.1002/chem.201705528Google Scholar53https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXisFaqtLc%253D&md5=0a02217fa42e5b28904502fb6e6ed569A Coordination Chemistry Approach to Fine-Tune the Physicochemical Parameters of Lanthanide Complexes Relevant to Medical ApplicationsLe Fur, Mariane; Molnar, Eniko; Beyler, Maryline; Kalman, Ferenc K.; Fougere, Olivier; Esteban-Gomez, David; Rousseaux, Olivier; Tripier, Raphael; Tircso, Gyula; Platas-Iglesias, CarlosChemistry - A European Journal (2018), 24 (13), 3127-3131CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)The geometric features of two pyclen-based ligands possessing identical donor atoms but different site organization have a profound impact in their complexation properties toward lanthanide ions. The ligand contg. two acetate groups and a picolinate arm arranged in a sym. fashion (L1) forms a Gd3+ complex being two orders of magnitude less stable than its dissym. analog GdL2. Besides, GdL1 experiences a much faster dissocn. following the acid-catalyzed mechanism than GdL2. On the contrary, GdL1 exhibits a lower exchange rate of the coordinated water mol. compared to GdL2. These very different properties are related to different strengths of the Gd-ligand bonds assocd. to steric effects, which hinder the coordination of a water mol. in GdL2 and the binding of acetate groups in GdL1.
- 54Roca-Sabio, A.; Regueiro-Figueroa, M.; Esteban-Gómez, D.; de Blas, A.; Rodríguez-Blas, T.; Platas-Iglesias, C. Density Functional Dependence of Molecular Geometries in Lanthanide(III) Complexes Relevant to Bioanalytical and Biomedical Applications. Comput. Theor. Chem. 2012, 999, 93– 104, DOI: 10.1016/j.comptc.2012.08.020Google Scholar54https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xhs1Gqs7jI&md5=3c5726b0bae1d7742f55d8ab06120b53Density functional dependence of molecular geometries in lanthanide(III) complexes relevant to bioanalytical and biomedical applicationsRoca-Sabio, Adrian; Regueiro-Figueroa, Martin; Esteban-Gomez, David; de Blas, Andres; Rodriguez-Blas, Teresa; Platas-Iglesias, CarlosComputational & Theoretical Chemistry (2012), 999 (), 93-104CODEN: CTCOA5; ISSN:2210-271X. (Elsevier B.V.)A set of 15 lanthanide-contg. model systems was used to evaluate the performance of 15 commonly available d. functionals (SVWN, SPL, BLYP, G96LYP, mPWLYP, B3LYP, BH&HLYP, B3PW91, BB95, mPWB95, TPSS, TPSSh, M06, CAM-B3LYP and wB97XD) in geometry detn., benchmarked against MP2 calcns. The best agreement between DFT optimized geometries and those obtained from MP2 calcns. is provided by meta-GGA and hybrid meta-GGA functionals. The use of hybrid-GGA functionals such as BH&HLYP and B3PW91 also provide reasonably good results, while B3LYP provides an important overestimation of the metal-ligand bonds. The performance of different basis sets to describe the ligand(s) atoms, as well as the use of large-core (LC) RECPs and small-core (SC) RECPs, has been also assessed. Our calcns. show that SCRECP calcns. provide somewhat shorter GdIII-donor distances than the LCRECP approach, the av. contraction of bond distances for the systems investigated amounting to 0.033 Å. However, geometry optimizations with the SCRECP (in combination with the mPWB95 functional and the 6-31G(d) basis set for the ligand atoms) take about 15 times longer than the LC counterparts, and about four times longer than MP2/LCRECP/6-31G(d) calcns. The 6-31G(d), 6-311G(d), 6-311G(d,p) or cc-pVDZ basis sets, in combination with LCRECPs, appear to offer an adequate balance between accuracy and computational cost for the description of mol. geometries of LnIII complexes. Electronic energies calcd. with the the cc-pVxZ family (x = D-6) indicate a relative fast convergence to the complete basis set (CBS) limit with basis set size. The inclusion of bulk solvent effects (IEFPCM) was shown to provoke an important impact on the calcd. geometries, particularly on the metal-nitrogen distances. Calcns. performed on lanthanide complexes relevant for practical applications confirmed the important effect of the solvent on the calcd. geometries.
- 55Inoue, M. B.; Inoue, M.; Muñoz, I. C.; Bruck, M. A.; Fernando, Q. Syntheses of New 15-Membered and 16-Membered Macrocyclic Ligands with Three Pendant Acetato Groups and the Structures of the Gadolinium(III) Complexes. Inorg. Chim. Acta 1993, 209, 29– 34, DOI: 10.1016/S0020-1693(00)84976-2Google Scholar55https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXms1Wmsrk%253D&md5=db33a0211f1baedc2ec3a50405445496Syntheses of new 15-membered and 16-membered macrocyclic ligands with three pendant acetato groups and the structures of the gadolinium(III) complexesInoue, Michiko B.; Inoue, Motomichi; Munoz, Iliana C.; Bruck, Michael A.; Fernando, QuintusInorganica Chimica Acta (1993), 209 (1), 29-34CODEN: ICHAA3; ISSN:0020-1693.A condensation of diethylenetriaminepentaacetic dianhydride with ethylenediamine gave a 15-membered macrocyclic ligand with 3 pendant acetato groups, (15-dtpa-en)H3 = C10H18N5O2(CH2CO2H)3; a 16-membered analog, (16-dtpa-pn)H3 = C11H20N5O2(CH2CO2H)3, was obtained using 1,3-propanediamine instead of ethylenediamine. The structures of their Gd(III) complexes, Gd2(15-dtpa-en)2.16H2O and Gd(16-dtpa-pn).4H2O, were detd. by x-ray analyses. Gd2(15-dtpa-en)2.16H2O crystd. as orthorhombic, space group Pbca, a 18.205(1), b 18.930(1), c 15.609(1) Å, Z = 4, R = 0.026, Rw = 0.042. Two Gd(III) ions are located between 2 ligand mols., forming a binuclear metal chelate mol. with a center of inversion. The coordination geometry around a metal ion is described as a distorted tricapped trigonal prism that consists of 9 coordinated atoms. Gd(16-dtpa-pn).4H2O crystd. as monoclinic, space group P21/c, a 8.246(2), b 14.995(3), c 19.367(4) Å, β 90.258(2)°, Z = 4, R = 0.021, Rw = 0.035. In this compd., a H2O mol. and a single ligand mol. are coordinated to a Gd(III), forming a mononuclear chelate with a tricapped trigonal prism. The structural differences between the 2 Gd(III) complexes are a result of the differences in the favorable conformations assumed by the 2 macrocyclic ligands.
- 56Bader, R. F. W.; Carroll, M. T.; Cheeseman, J. R.; Chang, C. Properties of Atoms in Molecules: Atomic Volumes. J. Am. Chem. Soc. 1987, 109 (26), 7968– 7979, DOI: 10.1021/ja00260a006Google Scholar56https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2sXmtlGlurc%253D&md5=0676f2a588f1104c3d65aa3a13d63b01Properties of atoms in molecules: atomic volumesBader, Richard F. W.; Carroll, Marshall T.; Cheeseman, James R.; Chang, ChengJournal of the American Chemical Society (1987), 109 (26), 7968-79CODEN: JACSAT; ISSN:0002-7863.The theory of atoms in mols. defines an atom and the av. values of its properties. The intersection of an at. surface, as defined by a property of the charge d., with a particular envelope of the charge d. defines the vol. of an atom in a mol. The value of the d. envelope used to bound the open portion of an at. region can be chosen on the basis of comparison with measured properties. The nature of the results are, in any event, independent of the choice for envelopes which contain >96% of the total electronic charge and lie within the usual range of van der Waals contact distances. It is shown that the vols. of Me and methylene groups in normal hydrocarbons are transferable properties, as are their charge distributions, populations, and energies. The vol. of a C atom subject to steric crowding decreases as its stability and electron population increase. This behavior is opposite to that found for a C atom in a system with geometric strain as found in cyclic and bicyclic mols. The stability, population, and vol. of a C atom all undergo parallel increases as the atom is subjected to an increasing degree of geometric strain. The vols. of the bridgehead C atoms in bicyclo[1.1.0]butane and [1.1.1]propellane are 1.2 and 1.5 times, resp., the vol. of a Me C atom. As anticipated on the basis of the orbital model, an increase in geometric strain is correlated with an increase in s character and thus finds the electron population, stability, and vol. of a C atom to undergo the same parallel increases in value through the series ethane, ethylene, acetylene. As a first step in the investigation of how atoms fit together, the changes in the at. vols. accompanying the formation of a H bond are detd.
- 57Neese, F. The ORCA Program System. WIREs Comput. Mol. Sci. 2012, 2 (1), 73– 78, DOI: 10.1002/wcms.81Google Scholar57https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhvFGls7s%253D&md5=a753e33a6f9a326553295596f5c754e5The ORCA program systemNeese, FrankWiley Interdisciplinary Reviews: Computational Molecular Science (2012), 2 (1), 73-78CODEN: WIRCAH; ISSN:1759-0884. (Wiley-Blackwell)A review. ORCA is a general-purpose quantum chem. program package that features virtually all modern electronic structure methods (d. functional theory, many-body perturbation and coupled cluster theories, and multireference and semiempirical methods). It is designed with the aim of generality, extendibility, efficiency, and user friendliness. Its main field of application is larger mols., transition metal complexes, and their spectroscopic properties. ORCA uses std. Gaussian basis functions and is fully parallelized. The article provides an overview of its current possibilities and documents its efficiency.
- 58Neese, F. Software Update: The ORCA Program System, Version 4.0. WIREs Comput. Mol. Sci. 2018, 8 (1), e1327 DOI: 10.1002/wcms.1327Google ScholarThere is no corresponding record for this reference.
- 59Reiher, M. Douglas–Kroll–Hess Theory: A Relativistic Electrons-Only Theory for Chemistry. Theor. Chem. Acc. 2006, 116 (1–3), 241– 252, DOI: 10.1007/s00214-005-0003-2Google Scholar59https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28Xns1Sqs7Y%253D&md5=32bd8fff4b0c49e80dcd3c97af2f34f4Douglas-Kroll-Hess Theory: A relativistic electrons-only theory for chemistryReiher, MarkusTheoretical Chemistry Accounts (2006), 116 (1-3), 241-252CODEN: TCACFW; ISSN:1432-881X. (Springer GmbH)A review. A unitary transformation allows to sep. (block-diagonalize) the Dirac Hamiltonian into two parts one part: solely describes electrons, while the other gives rise to neg.-energy states, which are the so-called positronic states. The block-diagonal form of the Hamiltonian no longer accounts for the coupling of both kinds of states. The pos.-energy ('electrons-only') part can serve as a 'fully' relativistic electrons-only theory, which can be understood as a rigorous basis for chem. Recent developments of the Douglas-Kroll-Hess (DKH) method allowed to derive a sequence of expressions, which approx. this electrons-only Hamiltonian up to arbitrary-order. While all previous work focused on the numerical stability and accuracy of these arbitrary-order DKH Hamiltonians, conceptual issues and paradoxa of the method were mostly left aside. In this work, the conceptual side of DKH theory is revisited in order to identify essential aspects of the theory to be distinguished from purely computational consideration.
- 60Chai, J.-D.; Head-Gordon, M. Long-Range Corrected Hybrid Density Functionals with Damped Atom–Atom Dispersion Corrections. Phys. Chem. Chem. Phys. 2008, 10 (44), 6615– 6620, DOI: 10.1039/b810189bGoogle Scholar60https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtlCksbfO&md5=c7848f8bf050e11972d438aaebd68fdfLong-range corrected hybrid density functionals with damped atom-atom dispersion correctionsChai, Jeng-Da; Head-Gordon, MartinPhysical Chemistry Chemical Physics (2008), 10 (44), 6615-6620CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)We report re-optimization of a recently proposed long-range cor. (LC) hybrid d. functional [J.-D. Chai and M. Head-Gordon, J. Chem. Phys., 2008, 128, 084106] to include empirical atom-atom dispersion corrections. The resulting functional, ωB97X-D yields satisfactory accuracy for thermochem., kinetics, and non-covalent interactions. Tests show that for non-covalent systems, ωB97X-D shows slight improvement over other empirical dispersion-cor. d. functionals, while for covalent systems and kinetics it performs noticeably better. Relative to our previous functionals, such as ωB97X, the new functional is significantly superior for non-bonded interactions, and very similar in performance for bonded interactions.
- 61Chai, J.-D.; Head-Gordon, M. Systematic Optimization of Long-Range Corrected Hybrid Density Functionals. J. Chem. Phys. 2008, 128 (8), 084106 DOI: 10.1063/1.2834918Google Scholar61https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXjtVGqtLk%253D&md5=9f138e05dabfb160b1aabaa185585207Systematic optimization of long-range corrected hybrid density functionalsChai, Jeng-Da; Head-Gordon, MartinJournal of Chemical Physics (2008), 128 (8), 084106/1-084106/15CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)A general scheme for systematically modeling long-range cor. (LC) hybrid d. functionals is proposed. Our resulting two LC hybrid functionals are shown to be accurate in thermochem., kinetics, and noncovalent interactions, when compared with common hybrid d. functionals. The qual. failures of the commonly used hybrid d. functionals in some "difficult problems," such as dissocn. of sym. radical cations and long-range charge-transfer excitations, are significantly reduced by the present LC hybrid d. functionals. (c) 2008 American Institute of Physics.
- 62Najibi, A.; Goerigk, L. The Nonlocal Kernel in van Der Waals Density Functionals as an Additive Correction: An Extensive Analysis with Special Emphasis on the B97M-V and ωB97M-V Approaches. J. Chem. Theory Comput. 2018, 14 (11), 5725– 5738, DOI: 10.1021/acs.jctc.8b00842Google Scholar62https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhvV2jsLzE&md5=6a1ebaf23b27f7222f3bda4516d82324The Nonlocal Kernel in van der Waals Density Functionals as an Additive Correction: An Extensive Analysis with Special Emphasis on the B97M-V and ωB97M-V ApproachesNajibi, Asim; Goerigk, LarsJournal of Chemical Theory and Computation (2018), 14 (11), 5725-5738CODEN: JCTCCE; ISSN:1549-9618. (American Chemical Society)The development of van der Waals d. functional approxns. (vdW-DFAs) has gained considerable interest over the past decade. While in a strictest sense, energy calcns. with vdW-DFAs should be carried out fully self-consistently, we demonstrate conclusively for a total of 11 methods that such a strategy only increases the computational time effort without having any significant effect on energetic properties, electron densities, or orbital-energy differences. The strategy to apply a nonlocal vdW-DFA kernel as an additive correction to a fully converged conventional DFA result is therefore justified and more efficient. As part of our study, we utilize the extensive GMTKN55 database for general main-group thermochem., kinetics, and noncovalent interactions [Phys. Chem. Chem. Phys.2017, 19, 32184], which allows us to analyze the very promising B97M-V [J. Chem. Phys. 2015, 142, 074111] and ωB97M-V [J. Chem. Phys. 2016, 144, 214110] DFAs. We also present new DFT-D3(BJ) based counterparts of these two methods and of ωB97X-V [J. Chem. Theory Comput 2013, 9, 263], which are faster variants with similar accuracy. Our study concludes with updated recommendations for the general method user, based on our current overview of 325 dispersion-cor. and -uncorrected DFA variants analyzed for GMTKN55. VdW-DFAs are the best representatives of the three highest rungs of Jacob's Ladder, namely, B97M-V, ωB97M-V, and DSD-PBEP86-NL.
- 63Weigend, F.; Ahlrichs, R. Balanced Basis Sets of Split Valence, Triple Zeta Valence and Quadruple Zeta Valence Quality for H to Rn: Design and Assessment of Accuracy. Phys. Chem. Chem. Phys. 2005, 7 (18), 3297– 3305, DOI: 10.1039/b508541aGoogle Scholar63https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXpsFWgu7o%253D&md5=a820fb6055c993b50c405ba0fc62b194Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: Design and assessment of accuracyWeigend, Florian; Ahlrichs, ReinhartPhysical Chemistry Chemical Physics (2005), 7 (18), 3297-3305CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)Gaussian basis sets of quadruple zeta valence quality for Rb-Rn are presented, as well as bases of split valence and triple zeta valence quality for H-Rn. The latter were obtained by (partly) modifying bases developed previously. A large set of more than 300 mols. representing (nearly) all elements-except lanthanides-in their common oxidn. states was used to assess the quality of the bases all across the periodic table. Quantities investigated were atomization energies, dipole moments and structure parameters for Hartree-Fock, d. functional theory and correlated methods, for which we had chosen Moller-Plesset perturbation theory as an example. Finally recommendations are given which type of basis set is used best for a certain level of theory and a desired quality of results.
- 64Pantazis, D. A.; Neese, F. All-Electron Scalar Relativistic Basis Sets for the Lanthanides. J. Chem. Theor. Comput. 2009, 5 (9), 2229– 2238, DOI: 10.1021/ct900090fGoogle Scholar64https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXpslaiu7o%253D&md5=edc7672c2e7514f1696d1fc2270e9611All-electron scalar relativistic basis sets for the lanthanidesPantazis, Dimitrios A.; Neese, FrankJournal of Chemical Theory and Computation (2009), 5 (9), 2229-2238CODEN: JCTCCE; ISSN:1549-9618. (American Chemical Society)Segmented all-electron relativistically contracted (SARC) basis sets are constructed for the elements 57La-71Lu and optimized for d. functional theory (DFT) applications. The basis sets are intended for use in combination with the DKH2 or ZORA scalar relativistic Hamiltonians for which individually optimized contractions are provided. Significant computational advantages can be realized owing to the loose contraction of the SARC basis sets compared to generally contracted basis sets, while their compact size allows them to replace effective core potentials for routine studies of lanthanide complexes. The new basis sets are evaluated in DFT calcns. of the first four ionization energies of the lanthanides. They yield results that accurately reproduce the exptl. trends, confirming a balanced treatment of different electronic configurations. The performance of the basis sets is further assessed in mol. systems with a comprehensive study of the lanthanide trihalides. Despite their compact size, the SARC basis sets demonstrate consistent, efficient, and reliable performance and will be esp. useful in calcns. of mol. properties that require explicit treatment of the core electrons.
- 65Bader, R. F. W. Atoms in Molecules. Acc. Chem. Res. 1985, 18, 9– 15, DOI: 10.1021/ar00109a003Google Scholar65https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2MXmtFGgsA%253D%253D&md5=602888ebc5fbe1c57b86efd88972306cAtoms in moleculesBader, R. F. W.Accounts of Chemical Research (1985), 18 (1), 9-15CODEN: ACHRE4; ISSN:0001-4842.A review with 21 refs.
- 66Tosi, M. P.; Fumi, F. G. Ionic Sizes And Born Repulsive Parameters In The NaCl-Type Alkali Halides-II: The Generalized Huggins-Mayer Form. J. Phys. Chem. Solids 1964, 25, 45– 52, DOI: 10.1016/0022-3697(64)90160-XGoogle Scholar66https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF2cXkvFKjtQ%253D%253D&md5=925d52709fa26f0090f5b6e4a5a564f7Ionic sizes and Born repulsive parameters in the NaCl-type alkali halides. II. Generalized Huggins-Mayer formsTosi, M. P.; Fumi, F. G.Journal of Physics and Chemistry of Solids (1964), 25 (1), 45-52CODEN: JPCSAW; ISSN:0022-3697.The procedure described for the detn. of the crystal radii of the ions in the individual NaCl-type alkali halides from solid-state data by the Born model is applied, adopting a generalized Huggins-Mayer form for the Born repulsive energy (i.e. allowing the hardness parameter to vary from salt to salt). The resulting values of the crystal radii agree within 0.05 A. with the values obtained with the Huggins-Mayer and Pauling forms. This indicates that the Born model, irrespective of the specific plausible form adopted for the Born repulsive energy, leads to relative values of the crystal radii for the alkali and halogen ions in the NaCl structure exceeding by ∼0.3 A. the traditional relative values, which refer to nearly free ions. Qual. and quant. evidence supporting these ionic deformations is discussed.
- 67Pauling, L. The Sizes of Ions and the Structure of Ionic Crystals. J. Am. Chem. Soc. 1927, 49 (3), 765– 790, DOI: 10.1021/ja01402a019Google Scholar67https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaB2sXhtFGjsw%253D%253D&md5=7142d81e5f65e04605b198cc0eaf09ccSizes of ions and structure of ionic crystalsPauling, LinusJournal of the American Chemical Society (1927), 49 (), 765-92CODEN: JACSAT; ISSN:0002-7863.With an at. model derived from the wave mechanics of Schr.ovrddot.odinger, size-screening consts. have been calcd. for the electrons in many-electron atoms and ions. After a discussion of the forces between ions, and of the significance of ionic sizes, values of the univalent crystal radius and the crystal radius are derived for a large no. of ions with the aid of these screening consts., using as a starting point the observed inter-atomic distances in crystals of NaF, KCl, RbBr, CsI and Li2O. The theoretical result is derived that ionic compds. MX2 will crystallize with fluorite structure if the radius ratio RM/RX is greater than 0.65, and with the rutile (or anatase) structure if it is less. This result is exptly. substantiated. Theoretically a binary compd. should have the sphalerite or wurzite structure instead of the NaCl structure if the radius ratio is less than 0.33. The oxide, sulfide, selenide and telluride of Be conform to this requirement, and are to be considered as ionic crystals. It is found, however, that such "tetrahedral" crystals are particularly apt to Show deformation, and it is suggested that this is a tendency of the anion to share an electron pair. with each cation.
- 68Lu, T.; Chen, F. Multiwfn: A Multifunctional Wavefunction Analyzer. J. Comput. Chem. 2012, 33 (5), 580– 592, DOI: 10.1002/jcc.22885Google Scholar68https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFykurjN&md5=deb758db27c2d0c4df698db0a3fd066fMultiwfn: A multifunctional wavefunction analyzerLu, Tian; Chen, FeiwuJournal of Computational Chemistry (2012), 33 (5), 580-592CODEN: JCCHDD; ISSN:0192-8651. (John Wiley & Sons, Inc.)Multiwfn is a multifunctional program for wavefunction anal. Its main functions are: (1) Calcg. and visualizing real space function, such as electrostatic potential and electron localization function at point, in a line, in a plane or in a spatial scope. (2) Population anal. (3) Bond order anal. (4) Orbital compn. anal. (5) Plot d.-of-states and spectrum. (6) Topol. anal. for electron d. Some other useful utilities involved in quantum chem. studies are also provided. The built-in graph module enables the results of wavefunction anal. to be plotted directly or exported to high-quality graphic file. The program interface is very user-friendly and suitable for both research and teaching purpose. The code of Multiwfn is substantially optimized and parallelized. Its efficiency is demonstrated to be significantly higher than related programs with the same functions. Five practical examples involving a wide variety of systems and anal. methods are given to illustrate the usefulness of Multiwfn. The program is free of charge and open-source. Its precompiled file and source codes are available from http://multiwfn.codeplex.com. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011.
- 69Wada, A.; Watanabe, M.; Yamanoi, Y.; Nishihara, H. Modification of the Luminescence Spectra of Chloro(Tetrapyridylcyclotetramine)Europium Complexes by Fine Tuning of the Eu–Cl Distance with Outer-Sphere Counterions in the Solid State, in a Polymer Matrix and in Solution. Chem. Commun. 2008, 1671– 1673, DOI: 10.1039/b716987fGoogle Scholar69https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXjs12ltb8%253D&md5=78052a8f6da214c93a7eb11cc50bc91fModification of the luminescence spectra of chloro(tetrapyridylcyclotetramine)europium complexes by fine tuning of the Eu-Cl distance with outer-sphere counterions in the solid state, in a polymer matrix and in solutionWada, Atsushi; Watanabe, Masayuki; Yamanoi, Yoshinori; Nishihara, HiroshiChemical Communications (Cambridge, United Kingdom) (2008), (14), 1671-1673CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)Controlling the coordination environments and the luminescence of Eu3+ complexes with outer-sphere counterions was achieved in the solid state, in a polymer matrix and in soln.
- 70Natrajan, L. S.; Khoabane, N. M.; Dadds, B. L.; Muryn, C. A.; Pritchard, R. G.; Heath, S. L.; Kenwright, A. M.; Kuprov, I.; Faulkner, S. Probing the Structure, Conformation, and Stereochemical Exchange in a Family of Lanthanide Complexes Derived from Tetrapyridyl-Appended Cyclen. Inorg. Chem. 2010, 49 (17), 7700– 7709, DOI: 10.1021/ic100447mGoogle Scholar70https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXpsVKltLk%253D&md5=d341e3030cb7e07f601633de58ab40f2Probing the Structure, Conformation, and Stereochemical Exchange in a Family of Lanthanide Complexes Derived from Tetrapyridyl-Appended CyclenNatrajan, Louise S.; Khoabane, Ntai M.; Dadds, Benjamin L.; Muryn, Christopher A.; Pritchard, Robin G.; Heath, Sarah L.; Kenwright, Alan M.; Kuprov, Ilya; Faulkner, StephenInorganic Chemistry (2010), 49 (17), 7700-7709CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)A series of lanthanide complexes have been synthesized from 1,4,7,10-tetrakis(2-pyridylmethyl)-1,4,7,10-tetraazacyclododecane (LPy). Crystallog. studies indicate that, in the solid phase, all of the lanthanide ions are 9-coordinate and are bound to eight N atoms from the donor ligand, with the ninth site being filled by a counterion or solvent mol. In soln., time-resolved luminescence studies indicate that the luminescence exhibits contributions from two species corresponding to the nonhydrated and hydrated forms. The NMR spectra in protic media show two dominant isomers on the NMR time scale; furthermore, the spectra are very different from those obtained for 1,4,7,10-tetraazacyclododecane-N',N'',N''',N''''-tetraacetic acid (DOTA) and its derivs. The different forms of the complex undergo slow conformational and enantiomeric exchange in soln., which has been measured by NMR. The exchange path has been mapped out by d. functional theory calcns. and shows multiple metastable conformations (with respect to the dihedral angles of the cyclen ring). This contrasts with the established NMR behavior of DOTA complexes, which has been described by a two-state soln. equil.
- 71Gunnlaugsson, T.; Davies, R. J. H.; Kruger, P. E.; Jensen, P.; McCabe, T.; Mulready, S.; O’Brien, J. E.; Stevenson, C. S.; Fanning, A.-M. Cyclen Based Lanthanide Ion Ribonuclease Mimics: The Effect of Pyridine Cofactors upon Phosphodiester HPNP Hydrolysis. Tetrahedron Lett. 2005, 46 (21), 3761– 3766, DOI: 10.1016/j.tetlet.2005.03.150Google Scholar71https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXjs1SnsL4%253D&md5=6b73afa76a124f9c3db82f8b39f67130Cyclen based lanthanide ion ribonuclease mimics: the effect of pyridine cofactors upon phosphodiester HPNP hydrolysisGunnlaugsson, Thorfinnur; Davies, R. Jeremy H.; Kruger, Paul E.; Jensen, Paul; McCabe, Thomas; Mulready, Sinead; O'Brien, John E.; Stevenson, Clarke S.; Fanning, Ann-MarieTetrahedron Letters (2005), 46 (21), 3761-3766CODEN: TELEAY; ISSN:0040-4039. (Elsevier B.V.)The cyclen based pyridine complexes 1Ln-3Ln (Ln = La(III) and Eu(III); 1-3 = N-(pyridin-x-yl)-2-[2,7,10-tris[(pyridin-x-ylcarbamoyl)methyl]-1,4,7,10-tetraazacyclododec-1-yl]acetamide (x = 2, 3, 4)) were synthesized as metallo-RNase mimics and their ability to hydrolytically cleave the phosphodiester of HPNP ((p-O2NC6H4O)(HOCHMeCH2O)PO2-) at 37° was studied using UV-visible spectroscopy, whereas the binding of the substrate was evaluated using 31P NMR and Eu(III)-luminescent measurements. In contrast 2Ln gave rise to fast pH dependent hydrolysis of HPNP, with max. efficiency at pH ∼8.2, and with a half-life of ∼1 h, the 1Ln and 3Ln complexes are inactive, emphasizing the importance of the nature of the pyridine isomer as a cofactor in the hydrolytic process. The crystal and mol. structures of the La, Eu and Gd complexes with the pyridin-3-yl-derived macrocycle were detd. by x-ray crystallog.
- 72Gao, J.; Ye, K.; He, M.; Xiong, W.-W.; Cao, W.; Lee, Z. Y.; Wang, Y.; Wu, T.; Huo, F.; Liu, X.; Zhang, Q. Tuning Metal–Carboxylate Coordination in Crystalline Metal–Organic Frameworks through Surfactant Media. J. Solid State Chem. 2013, 206, 27– 31, DOI: 10.1016/j.jssc.2013.07.031Google Scholar72https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsFKjt7nM&md5=92e5c8d8b7724afc9b1bd4e25e3c1df0Tuning metal-carboxylate coordination in crystalline metal-organic frameworks through surfactant mediaGao, Junkuo; Ye, Kaiqi; He, Mi; Xiong, Wei-Wei; Cao, Wenfang; Lee, Zhi Yi; Wang, Yue; Wu, Tom; Huo, Fengwei; Liu, Xiaogang; Zhang, QichunJournal of Solid State Chemistry (2013), 206 (), 27-31CODEN: JSSCBI; ISSN:0022-4596. (Elsevier B.V.)Although it was widely demonstrated that surfactants can efficiently control the size, shape and surface properties of micro/nanocrystals of metal-org. frameworks (MOFs) due to the strong interactions between surfactants and crystal facets of MOFs, the use of surfactants as reaction media to grow MOF single crystals is unprecedented. Compared with ionic liqs., surfactants are much cheaper and can have multifunctional properties such as acidic, basic, neutral, cationic, anionic, or even block. These factors strongly motivate the authors to develop a new synthetic strategy: growing cryst. MOFs in surfactants. Eight new two-dimensional (2D) or three-dimensional (3D) MOFs were successfully synthesized in an industrially-abundant and environmentally-friendly surfactant: polyethylene glycol-200 (PEG-200). Eight different coordination modes of carboxylates, ranging from monodentate η1 mode to tetra-donor coordination μ3-η1:η2:η1 mode, were founded in the authors' research. The magnetic properties of Co-based MOFs were studied and MOF NTU-Z6b showed a phase transition with a Curie temp. (Tc) at 5 K. The authors' strategy of growing cryst. MOFs in surfactant could offer exciting opportunities for prepg. novel MOFs with diverse structures and interesting properties.
- 73Gao, S.; George, S. J.; Zhou, Z.-H. Interaction of Gd-DTPA with Phosphate and Phosphite: Toward the Reaction Intermediate in Nephrogenic Systemic Fibrosis. Dalton Trans. 2016, 45 (12), 5388– 5394, DOI: 10.1039/C5DT04172DGoogle Scholar73https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XpsVWmtg%253D%253D&md5=f8a05ae3e4fddd24ba3a49fcf62dd89cInteraction of Gd-DTPA with phosphate and phosphite: toward the reaction intermediate in nephrogenic systemic fibrosisGao, Song; George, Simon J.; Zhou, Zhao-HuiDalton Transactions (2016), 45 (12), 5388-5394CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)Direct reactions of the MRI contrast agent K2[Gd(DTPA)(H2O)]·5H2O (1) (H5DTPA = diethylenetriaminepentaacetic acid) with dipotassium hydrogen phosphate (K2HPO4) or phosphite (K2HPO3) result in the isolation of well-defined Gd-DTPA phosphite K6[Gd2(DTPA)2(HPO3)]·7H2O (2) or phosphate K6[Gd2(DTPA)2(HPO4)]·10H2O (3), resp. Their lanthanum analogs K4[La2(DTPA)2(H2O)]·8H2O (4), K6[La2(DTPA)2(HPO3)]·7H2O (5) and K6[La2(DTPA)2(HPO4)]·10H2O (6) are used for comparison. The phosphate and phosphite groups are able to substitute the coordinated water mols. in 1 and 4 in a close physiol. aq. soln., and act as bridging ligands to link adjacent Ln(DTPA)2- (Ln = Gd and La) into dimeric structures. Solid state and soln. 13C NMR spectra of dimer 4 show complete dissocn. into its monomeric species in soln., while no dissocn. is obsd. for lanthanum phosphite 5 and phosphate 6 in soln., which show only one set of 13C spectra with the largest downfield shifts at 182.0 and 182.3 ppm resp. Comparisons of the bond distances and spectral data indicate that the interaction between DTPA and central Ln3+ cations are weakened after the substitutions, which support phosphate substituted Gd-DTPA as an initial intermediate in nephrogenic systemic fibrosis.
- 74Onate, C. A.; Okon, I. B.; Vincent, U. E.; Eyube, E. S.; Onyeaju, M. C.; Omugbe, E.; Egharevba, G. O. Non-Relativistic Molecular Modified Shifted Morse Potential System. Sci. Rep. 2022, 12 (1), 15188, DOI: 10.1038/s41598-022-19179-4Google Scholar74https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XitlKmsLfM&md5=6a62687a7a36cc124df3330ad4fb618cNon-relativistic molecular modified shifted Morse potential systemOnate, C. A.; Okon, I. B.; Vincent, U. E.; Eyube, E. S.; Onyeaju, M. C.; Omugbe, E.; Egharevba, G. O.Scientific Reports (2022), 12 (1), 15188CODEN: SRCEC3; ISSN:2045-2322. (Nature Portfolio)Abstr.: A shifted Morse potential model is modified to fit the study of the vibrational energies of some mols. Using a traditional technique/methodol., the vibrational energy and the un-normalized radial wave functions were calcd. for the modified shifted Morse potential model. The condition that fits the modified potential for mol. description were deduced together with the expression for the screening parameter. The vibrational energies of SiC, NbO, CP, PH, SiF, NH and Cs2 mols. were computed by inserting their resp. spectroscopic consts. into the calcd. energy equation. It was shown that the calcd. results for all the mols. agreement perfectly with the exptl. RKR values. The present potential performs better than Improved Morse and Morse potentials for cesium dimer. Finally, the real Morse potential model was obtained as a special case of the modified shifted potential.
- 75Janicki, R.; Mondry, A. Structural and Thermodynamic Aspects of Hydration of Gd(iii) Systems. Dalton Trans. 2019, 48, 3380– 3391, DOI: 10.1039/C8DT04869JGoogle Scholar75https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXjtlWgurw%253D&md5=d7e7dce566397d2e17dea7f1cf2a77a8Structural and thermodynamic aspects of hydration of Gd(III) systemsJanicki, Rafal; Mondry, AnnaDalton Transactions (2019), 48 (10), 3380-3391CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)X-ray crystal structures of Gd(III) and Lu(III) aqua ions as well as their complexes with polyaminopolycarboxylates (EDTA, CDTA, EGTA, DTPA, DOTA) were detd.: [Gd(H2O)9](CF3SO3)3, [Gd(H2O)8]Cl3·C10H20O5, [Lu(H2O)8]Cl3·C12H24O6·4H2O, [C(NH2)3][Gd(EDTA)(H2O)3], [C(NH2)3]2[Lu(EDTA)(H2O)2]ClO4·6H2O, [C(NH2)3][Lu(CDTA)(H2O)2]·6H2O, [C(NH2)3][Gd(EGTA)(H2O)]·2H2O, [C(NH2)2(N2H4)][Gd(HDTPA)(H2O)]·2H2O, Na[Gd(DOTA)(H2O)]·4H2O, and K2[Lu(DOTA)]Cl·4.6H2O. The weighted sums of UV absorption spectra of appropriate crystals were used to reproduce the spectra of the Gd(III) aq. solns. in the temp. range 276-363 K. In aq. soln. the Gd(III)-EGTA, Gd(III)-DTPA and Gd(III)-DOTA complexes exist as almost pure monohydrate [GdL(H2O)]n- species, while in the case of the Gd(III) aqua ion, Gd(III)-EDTA and Gd(III)-CDTA systems the equil. between variously hydrated species were found. The derived molar fractions of these species were used to det. the ΔG, ΔH and ΔS of hydration. These thermodn. functions may be derived not only from the spectra of the hypersensitive transitions, but from other f-f transitions as well. Next the ΔG, ΔH and ΔS values of hydration for the other Ln(III)-EDTA systems (Ln = Pr, Nd, Sm, Eu) were detd. The ΔG298 values of the dehydration reaction for Ln(III)-EDTA complexes (Ln = Pr, Nd, Sm, Eu, Gd, Ho, Er) were almost linearly dependent on the no. of 4f electrons in the whole series of lanthanides. Also, the point, where the ratio of [LnL(H2O)n] : [LnL(H2O)n-1] is 1, shifts along the lanthanide series depending on the ligand denticity - the higher the ligand denticity, the farther the point of the equimolar ratio in the lanthanide series. The presented results are the 1st systematic exptl. study on the thermodn. description of the hydration equil. of Gd(III) compds.
- 76Graeppi, N.; Hugh Powell, D.; Laurenczy, G.; Zékány, L.; Merbach, A. E. Coordination Equilibria and Water Exchange Kinetics of Lanthanide(III) Propylenediaminetetraacetates and Other Magnetic Resonance Imaging Related Complexes. Inorg. Chim. Acta 1995, 235 (1–2), 311– 326, DOI: 10.1016/0020-1693(95)90073-FGoogle Scholar76https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2MXnsFWmsLc%253D&md5=7f9401e5f1d21179c214e998c4d2480eCoordination equilibria and water exchange kinetics of lanthanide(III) propylenediaminetetraacetates and other magnetic resonance imaging related complexesGraeppi, Nicole; Powell, D. Hugh; Laurenczy, Gabor; Zekany, Laszlo; Merbach, Andre E.Inorganica Chimica Acta (1995), 235 (1-2), 311-26CODEN: ICHAA3; ISSN:0020-1693. (Elsevier)The UV-Vis absorption spectra of aq. solns. of Eu3+ complexes with the hexadentate polyaminocarboxylate ligands EDTA4-, CDTA4-, HDTA3- and PDTA4- were measured as a function of temp. and pressure in the frequency region corresponding to the 7F0→5D0 transition of Eu3+. The results can be explained in terms of equil. between nine-coordinate and eight-coordinate species where the eight-coordinate species contain one less inner sphere water mol. than the nine-coordinate species. The thermodn. parameters, including the reaction vol., for these equil. were detd. 17O NMR transverse relaxation rates and chem. shifts were measured for aq. solns. of the eight-coordinate complexes [Ln(PDTA)(H2O)2]- (Ln = Tb, Dy, Er, Tm, Yb) and [Er(EDTA)(H2O)2]- as a function of temp., pressure and magnetic field. The results were analyzed in terms of the water exchange kinetics on the complexes. The water exchange rate on [Ln(PDTA)(H2O)2]- decreases dramatically with decreasing ionic radius across the lanthanide series from kex298 = (2.4±0.1)×107 s-1 for Ln = Tb to kex298 = (2.8±0.3)×105 s-1 for Ln = Yb. The activation vols. show that this is accompanied by a change of exchange mechanism from associatively activated for Ln = Tb (ΔV # = -7.6±0.3 cm3 mol-1) to dissociatively activated for Ln = Yb (ΔV # = +7.4±0.8 cm3 mol-1). Water exchange on [Er(EDTA)(H2O)2]- (kex298 = (9.8±1.9)×106 s-1) is more than an order of magnitude faster than on [Er(PDTA)(H2O)2]- (kex298 = (5.6±0.5)×105 s-1). These kinetic results can be interpreted in terms of the equil. measured by UV-Vis spectrophotometry. The implications of these observations for the design of new MRI contrast agents are discussed.
- 77Balogh, E.; Mato-Iglesias, M.; Platas-Iglesias, C.; Tóth, É.; Djanashvili, K.; Peters, J. A.; de Blas, A.; Rodríguez-Blas, T. Pyridine- and Phosphonate-Containing Ligands for Stable Ln Complexation. Extremely Fast Water Exchange on the GdIII Chelates. Inorg. Chem. 2006, 45 (21), 8719– 8728, DOI: 10.1021/ic0604157Google Scholar77https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XptlWisLc%253D&md5=ec4d1fdf2126910d554d12897de69e8dPyridine- and Phosphonate-Containing Ligands for Stable Ln Complexation. Extremely Fast Water Exchange on the GdIII ChelatesBalogh, Edina; Mato-Iglesias, Marta; Platas-Iglesias, Carlos; Toth, Eva; Djanashvili, Kristina; Peters, Joop A.; de Blas, Andres; Rodriguez-Blas, TeresaInorganic Chemistry (2006), 45 (21), 8719-8728CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)Two novel ligands contg. pyridine units and phosphonate pendant arms, with ethane-1,2-diamine (L2) or cyclohexane-1,2-diamine (L3) backbones, have been synthesized for Ln complexation. The hydration nos. obtained from luminescence lifetime measurements in aq. solns. of the EuIII and TbIII complexes are q = 0.6 (EuL2), 0.7 (TbL2), 0.8 (EuL3), and 0.4 (TbL3). To further assess the hydration equil., we have performed a variable-temp. and -pressure UV-vis spectrophotometric study on the EuIII complexes. The reaction enthalpy, entropy, and vol. for the hydration equil. EuL ↔ EuL(H2O) were calcd. to be ΔH° = -(11.6 ± 2) kJ mol-1, ΔS° = -(34.2 ± 5) J mol-1 K-1, and KEu298 = 1.8 ± 0.3 for EuL2 and ΔH° = -(13.5 ± 1) kJ mol-1, ΔS° = -(41 ± 4) J mol-1 K-1, and KEu298 = 1.7 ± 0.3 for EuL3, resp. Variable-temp. 17O NMR and nuclear magnetic relaxation dispersion (NMRD) were measured for GdL2(H2O)q and GdL3(H2O)q systems. Given the presence of phosphonate groups in the ligand backbone, a second-sphere relaxation mechanism has been included for the anal. of the longitudinal 17O and 1H NMR relaxation rates. The water exchange rate on GdL2(H2O)q, kex298 = (7.0 ± 0.8) × 108 s-1, is extremely high and comparable to that on the GdIII aqua ion, while it is slightly reduced for GdL3(H2O)q, kex298 = (1.5 ± 0.1) × 108 s-1. This fast exchange can be rationalized in terms of a very flexible inner coordination sphere, which is slightly rigidified for L3 by the introduction of the cyclohexyl group on the amine backbone. The water exchange proceeds via a dissociative interchange mechanism, evidenced by the pos. activation vols. obtained from variable-pressure 17O NMR for both GdL2(H2O)q and GdL3(H2O)q (ΔV⧧ = +8.3 ± 1.0 and 8.7 ± 1.0 cm3 mol-1, resp.).
- 78Janicki, R.; Mondry, A. A New Approach to Determination of Hydration Equilibria Constants for the Case of [Er(EDTA)(H2O)n ]− Complexes. Phys. Chem. Chem. Phys. 2014, 16 (48), 26823– 26831, DOI: 10.1039/C4CP04093GGoogle Scholar78https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvVOmsLfJ&md5=037c1a5513f85b710478f25f8f7ef35cA new approach to determination of hydration equilibria constants for the case of [Er(EDTA)(H2O)n]- complexesJanicki, Rafal; Mondry, AnnaPhysical Chemistry Chemical Physics (2014), 16 (48), 26823-26831CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)Two anionic complexes [Er(EDTA)(H2O)2]- and [Er(EDTA)(H2O)3]- were obtained as the following compds.: [C(NH2)3]2[Er(EDTA)(H2O)2]ClO4·6H2O (1) and Na[Er(EDTA)(H2O)3]·5H2O (2), resp. The UV-visible-NIR absorption spectra of both monocrystals were measured at room temp. and at 4.2 K. The influence of coordination no. on intensities of the f-f transitions and the crystal field splitting of 2S+1LJ multiplets are discussed. The weighted sum of molar absorptivities of f-f transitions in the spectra of 1 and 2 was used to reproduce the absorption bands of the Er3+-EDTA complex in aq. soln. This approach allowed the authors to est. that the complex in soln. exists in 95% as the 8-coordinate [Er(EDTA)(H2O)2]- species and in 5% as the 9-coordinate [Er(EDTA)(H2O)3]- ones as well as to calc. the conditional hydration equil. const. (Kaqua) of the reaction: [Er(EDTA)(H2O)3]- ↔ [Er(EDTA)(H2O)2]- + H2O which is rather difficult to det. by using other methods. The Kaqua value is 19 ± 1.
- 79Zhang, J.; Dolg, M. Labile Capping Bonds in Lanthanide(III) Complexes: Shorter and Weaker. J. Phys. Chem. A 2015, 119 (4), 774– 780, DOI: 10.1021/jp511043cGoogle Scholar79https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitFOgsbnP&md5=50aaf22276bfd6fe7371eb2e6513f189Labile Capping Bonds in Lanthanide(III) Complexes: Shorter and WeakerZhang, Jun; Dolg, MichaelJournal of Physical Chemistry A (2015), 119 (4), 774-780CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)For a wide range of trivalent lanthanide ion coordination complexes of tricapped trigonal prism or monocapped square antiprism configurations, the bonds between the central lanthanide ions and the capping ligands are found to violate Badger's rule: they can get weaker as they get shorter. We demonstrate that this observation originates from the screening and repulsion effect of the prism ligands. Both effects enhance as the elec. field of the central ion or the softness of the prism ligands increases. Thus, for heavier lanthanides, despite the fact that the capping bond could be shorter, it is more efficient to be weakened by the prism ligands, being inherently labile. This concept of "labile capping bonds phenomenon" is then successfully used to interpret many problems in lanthanide(III) hydration, e.g., why the water exchange rate of a lanthanide(III) complex is much higher in a twisted square antiprism than in square antiprism configuration. Thus, the theory proposed in this paper offers new insights in understanding chem. problems.
- 80Quici, S.; Marzanni, G.; Forni, A.; Accorsi, G.; Barigelletti, F. New Lanthanide Complexes for Sensitized Visible and Near-IR Light Emission: Synthesis, 1H NMR, and X-Ray Structural Investigation and Photophysical Properties. Inorg. Chem. 2004, 43 (4), 1294– 1301, DOI: 10.1021/ic035143bGoogle Scholar80https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXntVaktg%253D%253D&md5=3b31dffdb21a1159ce731a8699e60085New Lanthanide Complexes for Sensitized Visible and Near-IR Light Emission: Synthesis, 1H NMR, and X-ray Structural Investigation and Photophysical PropertiesQuici, Silvio; Marzanni, Giovanni; Forni, Alessandra; Accorsi, Gianluca; Barigelletti, FrancescoInorganic Chemistry (2004), 43 (4), 1294-1301CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)The authors describe the syntheses, the 1H NMR studies in CD3OD and D2O as solvent, the x-ray characterization, and the luminescence properties in D2O soln. of the two complexes EuL and ErL (H3L = I), in which the phenanthroline unit which plays the role of light antenna for the sensitization process of the metal centered luminescence. In a previous report (Inorg. Chem. 2002, 41, 2777), for EuL there are no H2O mols. within the 1st coordination sphere. X-ray and 1H NMR results reported here are consistent with full satn. of the nine coordination sites within the EuL and ErL complexes. These studies provide important details regarding the conformations, square antiprism (SAP) and twisted square antiprism (TSAP), adopted in soln. by these complexes. The luminescence results are consistent with both an effective intersystem crossing (ISC) at the light absorbing phenanthroline unit (λexc = 278 nm) and an effective energy transfer (en) process from the phenanthroline donor to the cation acceptor (with unit or close to unit efficiency for both steps). In D2O solvent, the overall sensitization efficiency, φse, is 0.3 and 5 × 10-6, for EuL (main luminescence peaks at 585, 612, 699 nm) and ErL (luminescence peak at 1530 nm), resp. The photophys. properties of both complexes are discussed with ref. to their structural features as elucidated by the obtained 1H NMR and x-ray results.
- 81Storm Thomsen, M.; Andersen, H. O. B.; So̷rensen, T. J. Long Story Short: Donor Set Symmetry in [Eu(DOTA)(H2O)]− Crystals Determines the Electronic Structure. Dalton Trans. 2022, 51 (37), 14118– 14124, DOI: 10.1039/D2DT02172BGoogle Scholar81https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xit12qtbfF&md5=1107ad17412ec2e854b555bc9aa17513Long story short: donor set symmetry in [Eu(DOTA)(H2O)]- crystals determines the electronic structureStorm Thomsen, Maria; Andersen, Helene Obel Boech; Soerensen, Thomas JustDalton Transactions (2022), 51 (37), 14118-14124CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)Lanthanide complexes of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid DOTA have been studied in great detail due to their use as MRI contrast agents. Since the first report from Desreux in 1980, the Ln[DOTA]- complexes of gadolinium(III) in particular have been thoroughly investigated. The forms of the nine-coordinated [Ln(DOTA)(H2O)]- complexes are well known, and the ligand backbone has been used extensively to create functional MRI contrast agents, luminescent probes, and as a model system for studying the properties of lanthanide(III) ions. In soln., the photophys. properties have been mapped, but as the structures are not known, direct structure-property relationships have not been created. Here, the electronic properties of two Eu[DOTA] compds. (1 and 2) and a Eu[DOTA]-like compd. (3) were studied using single-crystal luminescence spectroscopy. The donor set in the three compds. is identical (4N 4O 1O), and using the symmetry deviation value σ-ideal it was shown that the coordination geometry is close to identical. Nevertheless, the electronic properties evaluated using the luminescence spectrum were found to differ significantly between the three compds. The magnitude of the crystal field splitting was found not to scale with the symmetry of the coordination geometry. It was concluded that the donor set dictates the splitting, yet the structure-property relationships governing the electronic properties of europium(III) ions still elude us.
- 82Howard, J. A. K.; Kenwright, A. M.; Moloney, J. M.; Parker, D.; Woods, M.; Howard, J. A. K.; Port, M.; Navet, M.; Rousseau, O. Structure and Dynamics of All of the Stereoisomers of Europium Complexes of Tetra(Carboxyethyl) Derivatives of Dota: Ring Inversion Is Decoupled from Cooperative Arm Rotation in the RRRR and RRRS Isomers. Chem. Commun. 1998, 13, 1381– 1382, DOI: 10.1039/a802847hGoogle ScholarThere is no corresponding record for this reference.
- 83Janicki, R.; Mondry, A. Structural and Thermodynamic Aspects of Hydration of Gd(iii) Systems. Dalton Trans. 2019, 48 (10), 3380– 3391, DOI: 10.1039/C8DT04869JGoogle Scholar83https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXjtlWgurw%253D&md5=d7e7dce566397d2e17dea7f1cf2a77a8Structural and thermodynamic aspects of hydration of Gd(III) systemsJanicki, Rafal; Mondry, AnnaDalton Transactions (2019), 48 (10), 3380-3391CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)X-ray crystal structures of Gd(III) and Lu(III) aqua ions as well as their complexes with polyaminopolycarboxylates (EDTA, CDTA, EGTA, DTPA, DOTA) were detd.: [Gd(H2O)9](CF3SO3)3, [Gd(H2O)8]Cl3·C10H20O5, [Lu(H2O)8]Cl3·C12H24O6·4H2O, [C(NH2)3][Gd(EDTA)(H2O)3], [C(NH2)3]2[Lu(EDTA)(H2O)2]ClO4·6H2O, [C(NH2)3][Lu(CDTA)(H2O)2]·6H2O, [C(NH2)3][Gd(EGTA)(H2O)]·2H2O, [C(NH2)2(N2H4)][Gd(HDTPA)(H2O)]·2H2O, Na[Gd(DOTA)(H2O)]·4H2O, and K2[Lu(DOTA)]Cl·4.6H2O. The weighted sums of UV absorption spectra of appropriate crystals were used to reproduce the spectra of the Gd(III) aq. solns. in the temp. range 276-363 K. In aq. soln. the Gd(III)-EGTA, Gd(III)-DTPA and Gd(III)-DOTA complexes exist as almost pure monohydrate [GdL(H2O)]n- species, while in the case of the Gd(III) aqua ion, Gd(III)-EDTA and Gd(III)-CDTA systems the equil. between variously hydrated species were found. The derived molar fractions of these species were used to det. the ΔG, ΔH and ΔS of hydration. These thermodn. functions may be derived not only from the spectra of the hypersensitive transitions, but from other f-f transitions as well. Next the ΔG, ΔH and ΔS values of hydration for the other Ln(III)-EDTA systems (Ln = Pr, Nd, Sm, Eu) were detd. The ΔG298 values of the dehydration reaction for Ln(III)-EDTA complexes (Ln = Pr, Nd, Sm, Eu, Gd, Ho, Er) were almost linearly dependent on the no. of 4f electrons in the whole series of lanthanides. Also, the point, where the ratio of [LnL(H2O)n] : [LnL(H2O)n-1] is 1, shifts along the lanthanide series depending on the ligand denticity - the higher the ligand denticity, the farther the point of the equimolar ratio in the lanthanide series. The presented results are the 1st systematic exptl. study on the thermodn. description of the hydration equil. of Gd(III) compds.
- 84Kriemen, E.; Holzapfel, M.; Ruf, E.; Rehbein, J.; Maison, W. Synthesis and Structural Analysis of 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraazidoethylacetic Acid (DOTAZA) Complexes. Eur. J. Inorg. Chem. 2015, 2015 (32), 5368– 5378, DOI: 10.1002/ejic.201500789Google Scholar84https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhslWksrrL&md5=d30e083cfe1d11fdc8c803ed5ec70108Synthesis and Structural Analysis of 1,4,7,10-Tetraazacyclododecane-1,4,7,10--tetraazidoethylacetic Acid (DOTAZA) ComplexesKriemen, Ella; Holzapfel, Malte; Ruf, Erik; Rehbein, Julia; Maison, WolfgangEuropean Journal of Inorganic Chemistry (2015), 2015 (32), 5368-5378CODEN: EJICFO; ISSN:1434-1948. (Wiley-VCH Verlag GmbH & Co. KGaA)Herein, the authors present the synthesis and structural anal. of metal complexes of enantiomerically pure 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraazidoethylacetic acid (DOTAZA, I). DOTAZA is a new tunable analog of DOTA, a clin. approved chelator for various pharmaceutically relevant metal ions. The authors study the complexation chem. of DOTAZA and report the crystal structures of a no. of complexes with pharmaceutically relevant metal ions such as Gd3+ [magnetic resonance imaging (MRI)], Eu3+ (luminescence spectroscopy), Y3+ [positron emission tomog. (PET)], In3+ [single-photon-emission computed tomog. (SPECT)], and Na+. These structures provide useful information for imaging applications and demonstrate the potential of DOTAZA to form stable complexes. Owing to its clickable azide functionalities, it may be used for the development of tailored imaging reagents that retain the pos. complexation chem. of the parent compd. DOTA.
- 85Siega, P.; Wuerges, J.; Arena, F.; Gianolio, E.; Fedosov, S. N.; Dreos, R.; Geremia, S.; Aime, S.; Randaccio, L. Release of Toxic Gd3+ Ions to Tumour Cells by Vitamin B12 Bioconjugates. Chem. – Eur. J. 2009, 15 (32), 7980– 7989, DOI: 10.1002/chem.200802680Google Scholar85https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXps1yrsbo%253D&md5=17a522233ac8a25cfce574857852fc66Release of Toxic Gd3+ Ions to Tumour Cells by Vitamin B12 BioconjugatesSiega, Patrizia; Wuerges, Jochen; Arena, Francesca; Gianolio, Eliana; Fedosov, Sergey N.; Dreos, Renata; Geremia, Silvano; Aime, Silvio; Randaccio, LucioChemistry - A European Journal (2009), 15 (32), 7980-7989, S7980/1-S7980/7CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Two probes consisting of vitamin B12 (CNCbl) conjugated to Gd chelates by esterification of the ribose 5'-OH moiety, Gd-DTPA-CNCbl (1; DTPA= diethylenetriamine-N,N,N',N'',N''-pentaacetic acid) and Gd-TTHA-CNCbl (2; TTHA= triethylenetetramine-N,N,N',N'',N''',N'''-hexaacetic acid), have been synthesized and characterized. The crystal structure of a dimeric form of 1, obtained by crystn. with an excess of GdCl3, has been detd. The kinetics of binding to and dissocn. from transcobalamin II show that 1 and 2 maintain high-affinity binding to the vitamin B12 transport protein. Complex 2 is very stable with respect to Gd3+ release owing to the satd. co-ordination of the Gd3+ ion by four amino and five carboxylate groups. Hydrolysis of the ester functionality occurs on the time scale of several hours. The lack of satn. and the possible involvement of the ester functionality in co-ordination result in lower stability of 1 towards hydrolysis and in a considerable release of Gd3+ in vitro. Gd3+ ions released from 1 are avidly taken up by the K562 tumor cells to an extent corresponding to approx. 1010 Gd3+ per cell. The internalization of toxic Gd3+ ions causes a marked decrease in cell viability as assessed by Trypan blue and WST-1 tests. On the contrary, the expts. with the more stable 2 did not show any significant cell internalization of Gd3+ ions and any influence on cell viability. The results point to new avenues of in situ generation of cytotoxic pathways based on the release of toxic Gd3+ ions by vitamin B12 bioconjugates.
- 86Campello, M. P. C.; Lacerda, S.; Santos, I. C.; Pereira, G. A.; Geraldes, C. F. G. C.; Kotek, J.; Hermann, P.; Vaněk, J.; Lubal, P.; Kubíček, V.; Tóth, É.; Santos, I. Lanthanide(III) Complexes of 4,10-Bis(Phosphonomethyl)-1,4,7,10-Tetraazacyclododecane-1,7-Diacetic Acid (Trans-H6do2a2p) in Solution and in the Solid State: Structural Studies Along the Series. Chem. – Eur. J. 2010, 16 (28), 8446– 8465, DOI: 10.1002/chem.201000320Google Scholar86https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXptlejtbg%253D&md5=dfc3cf9d059089ca3cf7c33340b8850cLanthanide(III) Complexes of 4,10-Bis(phosphonomethyl)-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (trans-H6do2a2p) in Solution and in the Solid State: Structural Studies Along the SeriesCampello, M. Paula C.; Lacerda, Sara; Santos, Isabel C.; Pereira, Giovannia A.; Geraldes, Carlos F. G. C.; Kotek, Jan; Hermann, Petr; Vanek, Jakub; Lubal, Premysl; Kubicek, Vojtech; Toth, Eva; Santos, IsabelChemistry - A European Journal (2010), 16 (28), 8446-8465, S8446/1-S8446/33CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Complexes of 4,10-bis(phosphonomethyl)-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (trans-H6do2a2p, H6L) with transition metal and lanthanide(III) ions were studied. The stability const. values of the divalent and trivalent metal-ion complexes are between the corresponding values of H4dota and H8dotp complexes, as a consequence of the ligand basicity. The solid-state structures of the ligand and of nine lanthanide(III) complexes were detd. by x-ray diffraction. All the complexes are present as twisted-square-antiprismatic isomers and their structures can be divided into two series. The first one involves nonacoordinated complexes of the large lanthanide(III) ions (Ce, Nd, Sm) with a coordinated H2O mol. For Sm, Eu, Tb, Dy, Er, Yb, the complexes are octacoordinated only by the ligand donor atoms and their coordination cages are more irregular. The formation kinetics and the acid-assisted dissocn. of several LnIII-H6L complexes were studied at different temps. and compared with analogous data for complexes of other dota-like ligands. The [Ce(L)(H2O)]3- complex is the most kinetically inert among complexes of the studied lanthanide(III) ions (Ce, Eu, Gd, Yb). Among mixed phosphonate-acetate dota analogs, kinetic inertness of the Ce(III) complexes is increased with a higher no. of phosphonate arms in the ligand, whereas the opposite is true for Eu(III) complexes. According to the 1H NMR spectroscopic pseudo-contact shifts for the Ce-Eu and Tb-Yb series, the soln. structures of the complexes reflect the structures of the [Ce(HL)(H2O)]2- and [Yb(HL)]2- anions, resp., found in the solid state. However, these soln. NMR spectroscopic studies showed that there is no unambiguous relation between 31P/1H lanthanide-induced shift (LIS) values and coordination of H2O in the complexes; the values rather express a relative position of the central ions between the N4 and O4 planes.
- 87Vojtíšek, P.; Cígler, P.; Kotek, J.; Rudovský, J.; Hermann, P.; Lukeš, I. Crystal Structures of Lanthanide(III) Complexes with Cyclen Derivative Bearing Three Acetate and One Methylphosphonate Pendants. Inorg. Chem. 2005, 44 (16), 5591– 5599, DOI: 10.1021/ic048190sGoogle Scholar87https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXmtVWhs74%253D&md5=c7f1952f2c9087e713b32ff0e4a2ba87Crystal Structures of Lanthanide(III) Complexes with Cyclen Derivative Bearing Three Acetate and One Methylphosphonate PendantsVojtisek, Pavel; Cigler, Petr; Kotek, Jan; Rudovsky, Jakub; Hermann, Petr; Lukes, IvanInorganic Chemistry (2005), 44 (16), 5591-5599CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)Lanthanide(III) complexes formulated as M[Ln(Hdo3ap)]·xH2O (M = Li; Ln = Tb, Dy, Lu, Y and M = H; Ln = Er, Lu) with the monophosphonate analog of H4dota, 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic-10-methylphosphonic acid (I; H5do3ap), were prepd. and studied using x-ray crystallog. All of the structures show that the (Hdo3ap)4- anion is octadentate coordinated to a lanthanide(III) ion similarly to the other H4dota-like ligands, i.e., forming O4 and N4 planes that are parallel and have mutual angle smaller than 3°. The lanthanide(III) ions lie between these planes, closer to the O4 base than to the N4 plane. All of the structures present the lanthanide(III) complexes in their twisted-square-antiprismatic (TSA) configuration. Twist angles of the pendants vary in the range between -24 and -30°, and for each complex, they lie in a very narrow region of 1°. The coordinated phosphonate oxygen is located slightly above (0.02-0.19 Å) the O3 plane formed with the coordinated acetates. The Dy, Y and Lu complexes are isostructural and can be formulated as [{Li(H2O)3}{M(Hdo3ap)}]·2H2O. These three complexes have a tetrahedral lithium coordinated only to one acetate O and 3 water mols. A water mol. is coordinated only in the terbium(III) and neodymium(III) complexes. The bond distance Tb-Ow is unusually long (2.678 Å). The O-Ln-O angles decrease from 140° [Nd(III)] to 121° [Lu(III)], thus confirming the increasing steric crowding around the water binding site. A comparison of a no. of structures of Ln(III) complexes with DOTA-like ligands shows that the TSA arrangement is flexible. However, the SA arrangement is rigid, and the derived structural parameters are almost identical for different ligands and lanthanide(III) ions.
- 88Bondi, A. Van Der Waals Volumes and Radii. J. Phys. Chem. 1964, 68 (3), 441– 451, DOI: 10.1021/j100785a001Google Scholar88https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF2cXls1Cgsg%253D%253D&md5=0f25964afae4e9f761e0d314151444a5van der Waals volumes and radiiBondi, A.Journal of Physical Chemistry (1964), 68 (3), 441-51CODEN: JPCHAX; ISSN:0022-3654.Intermol. van der Waals radii of the nonmetallic elements were assembled into a list of recommended values for vol. calcns. These values were arrived at by selecting from the most reliable x-ray diffraction data those which could be reconciled with crystal d. at 0°K. (to give reasonable packing d.), gas kinetic collision cross section, crit. d., and with liquid state properties. A qual. understanding of the nature of van der Waals radii is provided by correlation with the de Broglie wavelength of the outermost valence electron. Tentative values for the van der Waals radii of metallic elements in organometallic compds. are proposed. A list of increments for the vol. of mols. impenetrable to thermal collision, the so-called van der Waals vol., and of the corresponding increments in area per mol. is given.
- 89Rowland, R. S.; Taylor, R. Intermolecular Nonbonded Contact Distances in Organic Crystal Structures: Comparison with Distances Expected from van Der Waals Radii. J. Phys. Chem. 1996, 100 (18), 7384– 7391, DOI: 10.1021/jp953141+Google Scholar89https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28Xit1ykt7k%253D&md5=0308272c8e4653deb3823a27276975c4Intermolecular Nonbonded Contact Distances in Organic Crystal Structures: Comparison with Distances Expected from van der Waals RadiiRowland, R. Scott; Taylor, RobinJournal of Physical Chemistry (1996), 100 (18), 7384-91CODEN: JPCHAX; ISSN:0022-3654. (American Chemical Society)The conclusions derived from systematic analyses of intermol. contact distances in org. crystals may be affected by the values assumed for van der Waals radii. The most widely used tabulations of van der Waals radii date back 30 yr or more. Also, many of the tabulated values were chosen to reproduce vols., not contact distances, in crystals. Literally millions of nonbonded contact distances were characterized by crystallog. since the tabulations were compiled. A study has therefore been performed to establish the degree of consistency between these accumulated crystallog. data and the van der Waals radii of the common nonmetallic elements, as compiled by Pauling and Bondi. For halogens and S, the results show a remarkable agreement between obsd. contact distances and the Bondi radii. Agreement is slightly less good for C, N, and O, but discrepancies are still only ∼0.05 Å. However, there is a significant difference for H, where the Bondi value of 1.2 Å is probably too high by ∼0.1 Å.
- 90Fernández-Fernández, M. D. C.; Bastida, R.; Macías, A.; Pérez-Lourido, P.; Platas-Iglesias, C.; Valencia, L. Lanthanide(III) Complexes with a Tetrapyridine Pendant-Armed Macrocyclic Ligand: 1H NMR Structural Determination in Solution, X-Ray Diffraction, and Density-Functional Theory Calculations. Inorg. Chem. 2006, 45 (11), 4484– 4496, DOI: 10.1021/ic0603508Google Scholar90https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XktVSks7k%253D&md5=6d7e0be39ab445ef5ae9dd584d78fba9Lanthanide(III) Complexes with a Tetrapyridine Pendant-Armed Macrocyclic Ligand: 1H NMR Structural Determination in Solution, X-ray Diffraction, and Density-Functional Theory CalculationsFernandez-Fernandez, M. del C.; Bastida, R.; Macias, A.; Perez-Lourido, P.; Platas-Iglesias, C.; Valencia, L.Inorganic Chemistry (2006), 45 (11), 4484-4496CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)Complexes between the tetrapyridyl pendant-armed macrocyclic ligand (L) and the trivalent lanthanide ions were synthesized, and structural studies were made both in the solid state and in aq. soln. The crystal structures of the La, Ce, Pr, Gd, Tb, Er, and Tm complexes were detd. by single-crystal x-ray crystallog. In the solid state, all the cation complexes show a 10-coordinated geometry close to a distorted bicapped antiprism, with the pyridine pendants situated alternatively above and below the main plane of the macrocycle. The conformations of the two five-membered chelate rings present in the complexes change along the lanthanide series. The La(III) and Ce(III) complexes show a λδ (or δλ) conformation, while the complexes of the heavier lanthanide ions present λλ (or δδ) conformation. The cationic [Ln(L)]3+ complexes (Ln = La, Pr, Eu, Tb, and Tm) were also characterized by theor. calcns. at the d.-functional theory (DFT) B3LYP level. The theor. calcns. predict a stabilization of the λλ (or δδ) conformation on decreasing the ionic radius of the Ln(III) ion, in agreement with the exptl. evidence. The soln. structures show a good agreement with the calcd. ones, as demonstrated by paramagnetic NMR measurements (lanthanide induced shifts and relaxation rate enhancements). The 1H NMR spectra indicate an effective D2 symmetry of the complexes in D2O soln. The 1H lanthanide induced shifts (LIS) obsd. for the Ce(III), Tm(III), and Yb(III) complexes can be fit to a theor. model assuming that dipolar contributions are dominant for all protons. The resulting calcd. values are consistent with highly rhombic magnetic susceptibility tensors with the magnetic axes being coincident with the symmetry axes of the mol. In contrast with the solid-state structure, the anal. of the LIS data indicates that the Ce(III) complexes present a λλ (or δδ) conformation in soln.
- 91Castro, G.; Regueiro-Figueroa, M.; Esteban-Gómez, D.; Bastida, R.; Macías, A.; Pérez-Lourido, P.; Platas-Iglesias, C.; Valencia, L. Exceptionally Inert Lanthanide(III) PARACEST MRI Contrast Agents Based on an 18-Membered Macrocyclic Platform. Chem. – Eur. J. 2015, 21 (51), 18662– 18670, DOI: 10.1002/chem.201502937Google Scholar91https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhslyht7zP&md5=2c07436f30ef4a738ee9b4ee7f3232abExceptionally Inert Lanthanide(III) PARACEST MRI Contrast Agents Based on an 18-Membered Macrocyclic PlatformCastro, Goretti; Regueiro-Figueroa, Martin; Esteban-Gomez, David; Bastida, Rufina; Macias, Alejandro; Perez-Lourido, Paulo; Platas-Iglesias, Carlos; Valencia, LauraChemistry - A European Journal (2015), 21 (51), 18662-18670CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)We report a macrocyclic ligand based on a 3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane platform contg. four hydroxyethyl pendant arms (L1) that forms extraordinary inert complexes with Ln3+ ions. The [EuL1]3+ complex does not undergo dissocn. in 1 M HCl over a period of months at room temp. Furthermore, high concns. of phosphate and Zn2+ ions at room temp. do not provoke metal-complex dissocn. The X-ray crystal structures of six Ln3+ complexes reveal ten coordination of the ligand to the metal ions through the six nitrogen atoms of the macrocycle and the four oxygen atoms of the hydroxyethyl pendant arms. The anal. of the Yb3+- and Pr3+-induced paramagnetic 1H NMR shifts show that the solid-state structures are retained in aq. soln. The intensity of the 1H NMR signal of bulk water can be modulated by satn. of the signals of the hydroxy protons of Pr3+, Eu3+, and Yb3+ complexes following chem.-exchange satn. transfer (CEST). The ability of these complexes to provide large CEST effects at 25 and 37 °C and pH 7.4 was confirmed by using CEST magnetic resonance imaging expts.
- 92Xing, Y.; Jindal, A. K.; Regueiro-Figueroa, M.; Le Fur, M.; Kervarec, N.; Zhao, P.; Kovacs, Z.; Valencia, L.; Pérez-Lourido, P.; Tripier, R.; Esteban-Gómez, D.; Platas-Iglesias, C.; Sherry, A. D. The Relationship between NMR Chemical Shifts of Thermally Polarized and Hyperpolarized 89Y Complexes and Their Solution Structures. Chem. – Eur. J. 2016, 22 (46), 16657– 16667, DOI: 10.1002/chem.201602901Google Scholar92https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xhs1ClsLvN&md5=8f9701d055a6e3e2928a34694bea4b7cThe Relationship between NMR Chemical Shifts of Thermally Polarized and Hyperpolarized 89Y Complexes and Their Solution StructuresXing, Yixun; Jindal, Ashish K.; Regueiro-Figueroa, Martin; Le Fur, Mariane; Kervarec, Nelly; Zhao, Piyu; Kovacs, Zoltan; Valencia, Laura; Perez-Lourido, Paulo; Tripier, Raphael; Esteban-Gomez, David; Platas-Iglesias, Carlos; Sherry, A. DeanChemistry - A European Journal (2016), 22 (46), 16657-16667CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Recently developed dynamic nuclear polarization (DNP) technol. offers the potential of increasing the NMR sensitivity of even rare nuclei for biol. imaging applications. Hyperpolarized 89Y is an ideal candidate because of its narrow NMR linewidth, favorable spin quantum no. (I=1/2), and long longitudinal relaxation times (T1). Strong NMR signals were detected in hyperpolarized 89Y samples of a variety of yttrium complexes. A dataset of 89Y NMR data composed of 23 complexes with polyaminocarboxylate ligands was obtained using hyperpolarized 89Y measurements or 1H,89Y-HMQC spectroscopy. These data were used to derive an empirical equation that describes the correlation between the 89Y chem. shift and the chem. structure of the complexes. This empirical correlation serves as a guide for the design of 89Y sensors. Relativistic (DKH2) DFT calcns. were found to predict the exptl. 89Y chem. shifts to a rather good accuracy.
- 93Gambino, T.; Valencia, L.; Pérez-Lourido, P.; Esteban-Gómez, D.; Zaiss, M.; Platas-Iglesias, C.; Angelovski, G. Inert Macrocyclic Eu 3+ Complex with Affirmative paraCEST Features. Inorg. Chem. Front. 2020, 7 (12), 2274– 2286, DOI: 10.1039/C9QI01612KGoogle Scholar93https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXkvF2ltb4%253D&md5=4ed575859e442f900794501d32ceffdaInert macrocyclic Eu3+ complex with affirmative paraCEST featuresGambino, Tanja; Valencia, Laura; Perez-Lourido, Paulo; Esteban-Gomez, David; Zaiss, Moritz; Platas-Iglesias, Carlos; Angelovski, GoranInorganic Chemistry Frontiers (2020), 7 (12), 2274-2286CODEN: ICFNAW; ISSN:2052-1553. (Royal Society of Chemistry)We report on a macrocyclic platform based on an 18-membered macrocycle that forms kinetically highly inert paramagnetic complexes and possesses an excellent outlook for the development of bioresponsive paraCEST (paramagnetic chem. exchange satn. transfer) contrast agents. The investigated europium(III) chelate is non-hydrated and contains four amide groups, each possessing two paramagnetically shifted proton resonances distant from bulk water. The X-ray crystal structure and soln. studies indicate that the metal ion is ten-coordinated, being directly bound to the six N atoms of the macrocycle and the four amide O atoms of the pendant arms. The complex presents an excellent inertness with respect to dissocn., being stable under a variety of harsh conditions, including highly acidic and basic media or elevated temps. The amide protons are in slow-to-intermediate exchange with bulk water, which gives rise to the generation of a strong CEST effect at low probe concn. and satn. powers (~ 25% at 5 mM, B1 = 5 μT, 37 °C). We demonstrate the potential of this platform for mapping pH in its microenvironment and foresee potential for the development of diverse paraCEST probes and sensors.
- 94Harriswangler, C.; Caneda-Martínez, L.; Rousseaux, O.; Esteban-Gómez, D.; Fougère, O.; Pujales-Paradela, R.; Valencia, L.; Fernández, M. I.; Lepareur, N.; Platas-Iglesias, C. Versatile Macrocyclic Platform for the Complexation of [natY/90Y]Yttrium and Lanthanide Ions. Inorg. Chem. 2022, 61 (16), 6209– 6222, DOI: 10.1021/acs.inorgchem.2c00378Google Scholar94https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XpslajtLg%253D&md5=d1aa14660f7c9375e85d415b5ef686b1Versatile Macrocyclic Platform for the Complexation of [natY/90Y]Yttrium and Lanthanide IonsHarriswangler, Charlene; Caneda-Martinez, Laura; Rousseaux, Olivier; Esteban-Gomez, David; Fougere, Olivier; Pujales-Paradela, Rosa; Valencia, Laura; Fernandez, M. Isabel; Lepareur, Nicolas; Platas-Iglesias, CarlosInorganic Chemistry (2022), 61 (16), 6209-6222CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)We report a macrocyclic ligand (H3L6) based on a 3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane platform contg. three acetate pendant arms and a benzyl group attached to the fourth nitrogen atom of the macrocycle. The X-ray structures of the YL6 and TbL6 complexes reveal nine coordination of the ligand to the metal ions through the six nitrogen atoms of the macrocycle and three oxygen atoms of the carboxylate pendants. A combination of NMR spectroscopic studies (1H, 13C, and 89Y) and DFT calcns. indicated that the structure of the YL6 complex in the solid state is maintained in an aq. soln. The detailed study of the emission spectra of the EuL6 and TbL6 complexes revealed Ln3+-centered emission with quantum yields of 7.0 and 60%, resp. Emission lifetime measurements indicate that the ligand offers good protection of the metal ions from surrounding water mols., preventing the coordination of water mols. The YL6 complex is remarkably inert with respect to complex dissocn., with a lifetime of 1.7 h in 1 M HCl. On the other hand, complex formation is fast (~ 1 min at pH 5.4, 2 × 10-5 M). Studies using the 90Y-nuclide confirmed fast radiolabeling since [90Y]YL6 is nearly quant. formed (radiochem. yield (RCY) > 95) in a short time over a broad range of pH values from ca. 2.4 to 9.0. Challenging expts. in the presence of excess EDTA and in human serum revealed good stability of the [90Y]YL6 complex. All of these expts. combined suggest the potential application of H3L6 derivs. as Y-based radiopharmaceuticals.
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- 1Parker, D.; Dickins, R. S.; Puschmann, H.; Crossland, C.; Howard, J. A. K. Being Excited by Lanthanide Coordination Complexes: Aqua Species, Chirality, Excited-State Chemistry, and Exchange Dynamics. Chem. Rev. 2002, 102, 1977– 2010, DOI: 10.1021/cr010452+1https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38Xjslens7c%253D&md5=0e63a0a7979334bb84c640320528be70Being Excited by Lanthanide Coordination Complexes: Aqua Species, Chirality, Excited-State Chemistry, and Exchange DynamicsParker, David; Dickins, Rachel S.; Puschmann, Horst; Crossland, Clare; Howard, Judith A. K.Chemical Reviews (Washington, DC, United States) (2002), 102 (6), 1977-2010CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. Lanthanide (Ln) coordination complexes are reviewed with emphasis on structural anal. of 9-coordinate aqua-Ln species, chirality in aq. soln., exchange dynamics, excited-state chem. and magnetic resonance applications.
- 2Marcus, Y. Thermodynamics of Solvation of Ions. J. Chem. Soc., Faraday Trans. 1991, 87, 2995– 2999, DOI: 10.1039/FT99187029952https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3MXmsVWhsbc%253D&md5=96b15991eae292d32845508f6c99a5a7Thermodynamics of solvation of ions. 5. Gibbs free energy of hydration at 298.15 KMarcus, YizhakJournal of the Chemical Society, Faraday Transactions (1991), 87 (18), 2995-9CODEN: JCFTEV; ISSN:0956-5000.The std. molar free energies of hydration, ΔhvdG0, of 109 (mainly inorg.) ions ranging in their charges from -3 to +4 were compiled and interpreted in terms of a model used previously for other thermodn. quantities of hydration. The main contributions to ΔhydG0 are the electrostatic effects, resulting in solvent immobilization, electrostriction, and dielec. satn. in a hydration shell of specified thickness, and further such effects on the water that surrounds this shell. Other effects contribute to ΔhydG0 to a minor extent only.
- 3Regueiro-Figueroa, M.; Esteban-Gómez, D.; de Blas, A.; Rodríguez-Blas, T.; Platas-Iglesias, C. Understanding Stability Trends along the Lanthanide Series. Chem. – Eur. J. 2014, 20 (14), 3974– 3981, DOI: 10.1002/chem.2013044693https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXjt12gtrg%253D&md5=8a2ef02e4bef4d8ad4e62c25243a08ddUnderstanding Stability Trends along the Lanthanide SeriesRegueiro-Figueroa, Martin; Esteban-Gomez, David; de Blas, Andres; Rodriguez-Blas, Teresa; Platas-Iglesias, CarlosChemistry - A European Journal (2014), 20 (14), 3974-3981CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)The stability trends across the lanthanide series of complexes with the polyaminocarboxylate ligands TETA4- (H4TETA = 2,2',2'',2'''-(1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrayl)tetraacetic acid), BCAED4- (H4BCAED = 2,2',2'',2'''-{[(1,4-diazepane-1,4-diyl)bis(ethane-2,1-diyl)]bis(azanetriyl)}tetraacetic acid), and BP18C62- (H2BP18C6 = 6,6'-[(1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene)]dipicolinic acid) were investigated using DFT calcns. Geometry optimizations performed at the TPSSh/6-31G(d,p) level, and using a 46 + 4fn ECP for lanthanides, provide bond lengths of the metal coordination environments in good agreement with the exptl. values obsd. in the X-ray structures. The contractions of the Ln3+ coordination spheres follow quadratic trends, as obsd. previously for different isostructural series of complexes. We show here that the parameters obtained from the quant. anal. of these data can be used to rationalize the obsd. stability trends across the 4f period. The stability trends along the lanthanide series were also evaluated by calcg. the free energy for the reaction [La(L)]n+/-(sol) + Ln3+(sol)→[Ln(L)]n+/-(sol) + La3+(sol). A parameterization of the Ln3+ radii was performed by minimizing the differences between exptl. and calcd. std. hydration free energies. The calcd. stability trends are in good agreement with the exptl. stability consts., which increase markedly across the series for BCAED4- complexes, increase smoothly for the TETA4- analogs, and decrease in the case of BP18C62- complexes. The resulting stability trend is the result of a subtle balance between the increased binding energies of the ligand across the lanthanide series, which contribute to an increasing complex stability, and the increase in the abs. values of hydration energies along the 4f period.
- 4Pearson, R. Hard and Soft Acids and Bases. J. Am. Chem. Soc. 1963, 85, 3533– 3539, DOI: 10.1021/ja00905a0014https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF2cXksV0%253D&md5=2333a18c8168b373b612f5f45e8f4b4cHard and soft acids and basesPearson, Ralph G.Journal of the American Chemical Society (1963), 85 (22), 3533-9CODEN: JACSAT; ISSN:0002-7863.A number of Lewis acids of diverse types are classified as (a) or (b) following the criterion of Ahrland, et al. (CA 53, 960c). Other, auxiliary criteria are proposed. Class (a) acids prefer to bind to "hard" or nonpolarizable bases. Class (b) acids prefer to bind to "soft" or polarizable bases. Since class (a) acids are themselves "hard" and since class (b) acids are "soft" a simple, useful rule is proposed: hard acids bind strongly to hard bases and soft acids bind strongly to soft bases. The explanations for such behavior include: (1) various degrees of ionic and covalent σ-bonding; (2) π-bonding; (3) electron correlation phenomena; (4) solvation effects.
- 5Cotton, S. A. Establishing Coordination Numbers for the Lanthanides in Simple Complexes. C. R. Chim. 2005, 8 (2), 129– 145, DOI: 10.1016/j.crci.2004.07.0025https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXhtlOgt7w%253D&md5=1e8d7ff840544ef9f9045aca9095dcb9Establishing coordination numbers for the lanthanides in simple complexesCotton, Simon A.Comptes Rendus Chimie (2005), 8 (2), 129-145CODEN: CRCOCR; ISSN:1631-0748. (Editions Scientifiques et Medicales Elsevier)A review. This article reviews the development of the understanding of the coordination no. in lanthanide complexes, showing how it was realized in the 1960s that lanthanide complexes frequently had much higher coordination nos. than 6, and how it subsequently became possible for chemists to synthesize compds. with coordination nos. as low as 2, 3 and 4. Subsequent sections examine how coordination of solvent can cause uncertainties in coordination nos.; the detn. of the coordination no. of the aqua ions and in hydrated salts; variations (or not) in coordination no. across the lanthanide series; the effect of counterion upon coordination no.; and agostic interactions and interactions with distant atoms (when is a bond not a bond).
- 6Bünzli, J.-C. G. Review: Lanthanide Coordination Chemistry: From Old Concepts to Coordination Polymers. J. Coord. Chem. 2014, 67 (23–24), 3706– 3733, DOI: 10.1080/00958972.2014.957201There is no corresponding record for this reference.
- 7Moeller, T.; Thompson, L. C. Observations on the Rare Earths--LXXV. The Stabilities of Diethylenetriaminepentaacetic Acid Chelates. J. Inorg. Nucl. Chem. 1962, 24, 499– 510, DOI: 10.1016/0022-1902(62)80236-X7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF3sXisV2lug%253D%253D&md5=c1623277d4bde5a9040aefeb8fdbd415The rare earths. LXXV. The stabilities of diethylenetriaminepentaacetic acid chelatesMoeller, T.; Thompson, L. C.Journal of Inorganic and Nuclear Chemistry (1962), 24 (), 499-510CODEN: JINCAO; ISSN:0022-1902.cf. CA 56, 6727b, 11002h. The interaction between diethylenetriaminepentaacetic acid (H5DTPA or H5Z) and rare earth metal ions (Ln+++) was investigated. The acid formation consts. of the H chelates (LnHZ-) and the formation consts. of the normal chelates (LnZ--) were obtained at 10, 20, and 30°, and an ionic strength of 0.1 (KNO3), the former by a titration technique and the latter by a Hg indicator electrode technique. δH° and δS° were detd. Although errors in these functions are substantial, the functions were related to observed trends in stability. The dissocn. consts. for the last 3 protons of diethylenetriaminepentaacetic acid were measured as a function of temp. at ionic strength 0.1 (KNO3) and converted to thermodynamic functions by least squares analysis. These functions were compared with corresponding values for related chelating agents.
- 8Loncin, M. F.; Desreux, J. F.; Merciny, E. Coordination of Lanthanides by Two Polyamino Polycarboxylic Macrocycles: Formation of Highly Stable Lanthanide Complexes. Inorg. Chem. 1986, 25 (15), 2646– 2648, DOI: 10.1021/ic00235a0318https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL28XktlSru7Y%253D&md5=4c39cb8d450f964098f9844771f5f07dCoordination of lanthanides by two polyamino polycarboxylic macrocycles: formation of highly stable lanthanide complexesLoncin, M. F.; Desreux, J. F.; Merciny, E.Inorganic Chemistry (1986), 25 (15), 2646-8CODEN: INOCAJ; ISSN:0020-1669.The formation consts. of a few lanthanide complexes with DOTA (1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid) and TETA (1,4,8,11-tetraazacyclotetradecane-N,N',N'',N'''-tetraacetic acid) were measured by potentiometric and competition methods. The ligand DOTA forms the most stable lanthanide chelates known so far (log KML = 28.2-29.2) while the stability of the TETA compds. at 80° (log KML = 14.5-16.5) is comparable to the stability of the EDTA complexes. A competition method with the C2O42- anion as a probe had to be used for detg. the formation consts. of the DOTA lanthanide chelates because of the high stability of these compds. The relative stability of the DOTA and TETA complexes is accounted for by steric factors with ref. to known soln.- and solid-state structures.
- 9Clough, T. J.; Jiang, L.; Wong, K.-L.; Long, N. J. Ligand Design Strategies to Increase Stability of Gadolinium-Based Magnetic Resonance Imaging Contrast Agents. Nat. Commun. 2019, 10 (1), 1420, DOI: 10.1038/s41467-019-09342-39https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB3cbps1GhsA%253D%253D&md5=1b6079d3ddddbd8b72eb7901c6d0ec3eLigand design strategies to increase stability of gadolinium-based magnetic resonance imaging contrast agentsClough Thomas J; Jiang Lijun; Long Nicholas J; Jiang Lijun; Wong Ka-LeungNature communications (2019), 10 (1), 1420 ISSN:.Gadolinium(III) complexes have been widely utilised as magnetic resonance imaging (MRI) contrast agents for decades. In recent years however, concerns have developed about their toxicity, believed to derive from demetallation of the complexes in vivo, and the relatively large quantities of compound required for a successful scan. Recent efforts have sought to enhance the relaxivity of trivalent gadolinium complexes without sacrificing their stability. This review aims to examine the strategic design of ligands synthesised for this purpose, provide an overview of recent successes in gadolinium-based contrast agent development and assess the requirements for clinical translation.
- 10Uzal-Varela, R.; Rodríguez-Rodríguez, A.; Wang, H.; Esteban-Gómez, D.; Brandariz, I.; Gale, E. M.; Caravan, P.; Platas-Iglesias, C. Prediction of Gd(III) Complex Thermodynamic Stability. Coord. Chem. Rev. 2022, 467, 214606 DOI: 10.1016/j.ccr.2022.21460610https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhtlOrs7vO&md5=817d25df92de6eb2acc1c7a99c13031bPrediction of Gd(III) complex thermodynamic stabilityUzal-Varela, Rocio; Rodriguez-Rodriguez, Aurora; Wang, Huan; Esteban-Gomez, David; Brandariz, Isabel; Gale, Eric M.; Caravan, Peter; Platas-Iglesias, CarlosCoordination Chemistry Reviews (2022), 467 (), 214606CODEN: CCHRAM; ISSN:0010-8545. (Elsevier B.V.)Gadolinium(III) complexes are widely employed as contrast agents in diagnostic magnetic resonance imaging, and the development of new contrast agents remains a highly active field. A key requisite for contrast agents is high thermodn. stability of the complex to ensure that the Gd(III) ion is not released in the body. Here we utilized published stability consts. spanning 20 orders of magnitude to develop empirical expressions based on structural descriptors to predict the Gd(III)-ligand formation const. as well as pGd at pH 7.4. We then tested the predictive power of these expressions and found excellent agreement with a mean deviation of 1.0 log K units. The magnitudes of the structural descriptors are useful for guiding ligand design for Gd(III), and the empirical stability const. expressions can be used to screen potential ligands. This methodol. is readily extended to other aq. metal ion systems.
- 11Wahsner, J.; Gale, E. M.; Rodríguez-Rodríguez, A.; Caravan, P. Chemistry of MRI Contrast Agents: Current Challenges and New Frontiers. Chem. Rev. 2019, 119 (2), 957– 1057, DOI: 10.1021/acs.chemrev.8b0036311https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhvFWhsLfM&md5=3bf91b184710feb5d10f3249eff7ac02Chemistry of MRI Contrast Agents: Current Challenges and New FrontiersWahsner, Jessica; Gale, Eric M.; Rodriguez-Rodriguez, Aurora; Caravan, PeterChemical Reviews (Washington, DC, United States) (2019), 119 (2), 957-1057CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. Tens of millions of contrast-enhanced magnetic resonance imaging (MRI) exams are performed annually around the world. The contrast agents, which improve diagnostic accuracy, are almost exclusively small, hydrophilic gadolinium(III) based chelates. In recent years concerns have arisen surrounding the long-term safety of these compds., and this has spurred research into alternatives. There has also been a push to develop new molecularly targeted contrast agents or agents that can sense pathol. changes in the local environment. This comprehensive review describes the state of the art of clin. approved contrast agents, their mechanism of action, and factors influencing their safety. From there we describe different mechanisms of generating MR image contrast such as relaxation, chem. exchange satn. transfer, and direct detection and the types of mols. that are effective for these purposes. Next we describe efforts to make safer contrast agents either by increasing relaxivity, increasing resistance to metal ion release, or by moving to gadolinium(III)-free alternatives. Finally we survey approaches to make contrast agents more specific for pathol. either by direct biochem. targeting or by the design of responsive or activatable contrast agents.
- 12Kostelnik, T. I.; Orvig, C. Radioactive Main Group and Rare Earth Metals for Imaging and Therapy. Chem. Rev. 2019, 119 (2), 902– 956, DOI: 10.1021/acs.chemrev.8b0029412https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitVenu7bP&md5=5ea88568fccd143b1c617130cbfe6a08Radioactive Main Group and Rare Earth Metals for Imaging and TherapyKostelnik, Thomas I.; Orvig, ChrisChemical Reviews (Washington, DC, United States) (2019), 119 (2), 902-956CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)Radiometals possess an exceptional breadth of decay properties and have been applied to medicine with great success for several decades. The majority of current clin. use involves diagnostic procedures, which use either positron-emission tomog. (PET) or single-photon imaging to detect anat. abnormalities that are difficult to visualize using conventional imaging techniques (e.g., MRI and X-ray). The potential of therapeutic radiometals has more recently been realized and relies on ionizing radiation to induce irreversible DNA damage, resulting in cell death. In both cases, radiopharmaceutical development has been largely geared toward the field of oncol.; thus, selective tumor targeting is often essential for efficacious drug use. To this end, the rational design of four-component radiopharmaceuticals has become popularized. This Review introduces fundamental concepts of drug design and applications, with particular emphasis on bifunctional chelators (BFCs), which ensure secure consolidation of the radiometal and targeting vector and are integral for optimal drug performance. Also presented are detailed accounts of prodn., chelation chem., and biol. use of selected main group and rare earth radiometals.
- 13Bünzli, J.-C. G. Lanthanide Luminescence for Biomedical Analyses and Imaging. Chem. Rev. 2010, 110 (5), 2729– 2755, DOI: 10.1021/cr900362e13https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhvFGqu7o%253D&md5=d042b6946d5b26f5ac056182fc9a3ecbLanthanide Luminescence for Biomedical Analyses and ImagingBunzli, Jean-Claude G.Chemical Reviews (Washington, DC, United States) (2010), 110 (5), 2729-2755CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. This review addresses the problematics of lanthanide luminescent bioprobes (LLB) from the standpoint of their photophys. and biochem. properties; a broad overview of the various applications in which LLBs have been applied is given.
- 14Bünzli, J.-C. G. On the Design of Highly Luminescent Lanthanide Complexes. Coord. Chem. Rev. 2015, 293–294, 19– 47, DOI: 10.1016/j.ccr.2014.10.01314https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvFSmtbzF&md5=4d963c71116add3fd9f9f1de5c4b96c4On the design of highly luminescent lanthanide complexesBunzli, Jean-Claude G.Coordination Chemistry Reviews (2015), 293-294 (), 19-47CODEN: CCHRAM; ISSN:0010-8545. (Elsevier B.V.)Presently, phosphors and luminescent materials for lighting, telecommunications, displays, security inks and marking, as well as for probes in biosciences represent one third of the total value of the lanthanides used worldwide. If optical glasses and laser materials are added, this figure is close to 40%, explaining the large interest that the scientific community is devoting to such materials. The present review focuses on the design of highly luminescent lanthanide complexes and discusses all aspects needing optimization. Ref. is made to the mastering of the various energy migration processes in luminescence sensitization by org. ligands, to minimizing non-radiative deactivation mechanisms, as well as to other parameters such as the radiative lifetime, the refractive index, and the benefit of inserting luminescent complexes into inorg.-hybrid structures. Comparative tables list the most luminescent complexes emitting in the visible and near-IR ranges and the best chromophores are pointed out.
- 15Nonat, A. M.; Charbonnière, L. J. Upconversion of Light with Molecular and Supramolecular Lanthanide Complexes. Coord. Chem. Rev. 2020, 409, 213192 DOI: 10.1016/j.ccr.2020.21319215https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhvFartrg%253D&md5=10f2d7aee5a57b6ba10a3ba81ef2cc6cUpconversion of light with molecular and supramolecular lanthanide complexesNonat, Aline M.; Charbonniere, Loic J.Coordination Chemistry Reviews (2020), 409 (), 213192CODEN: CCHRAM; ISSN:0010-8545. (Elsevier B.V.)A review. Upconversion (UC) is the process by which the energy of multiple photons is absorbed by a compd. and restored in the form of a photon of higher energy than the incident light, resulting in an anti-Stokes process. Although studied theor. since the middle of the last century and exptl. obsd. in the 1960's, the process was up to recently mainly restricted to solid state devices and ultimately to nanoparticles at the end of the century. At the same period, different researches were directed towards the possibility to observe UC at the mol. level and it is only recently that the phenomenon could be obsd. in discrete mol. entities in soln. with still very few examples. This review aims at explaining the difficulties encountered at the mol. level compared to the solid state and summarizes the results reported to date on UC at the mol. scale.
- 16Aboshyan-Sorgho, L.; Cantuel, M.; Petoud, S.; Hauser, A.; Piguet, C. Optical Sensitization and Upconversion in Discrete Polynuclear Chromium–Lanthanide Complexes. Coord. Chem. Rev. 2012, 256 (15–16), 1644– 1663, DOI: 10.1016/j.ccr.2011.12.01316https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhslGls7k%253D&md5=98b1b975355f94479b58e79a64102348Optical sensitization and upconversion in discrete polynuclear chromium-lanthanide complexesAboshyan-Sorgho, Lilit; Cantuel, Martine; Petoud, Stephane; Hauser, Andreas; Piguet, ClaudeCoordination Chemistry Reviews (2012), 256 (15-16), 1644-1663CODEN: CCHRAM; ISSN:0010-8545. (Elsevier B.V.)A review. Due to its extreme kinetic inertness, trivalent chromium, Cr(III), has been rarely combined with labile trivalent lanthanides, Ln(III), to give discrete self-assembled (supra)mol. polynuclear complexes. However, the plethora of accessible metal-centered excited states possessing variable lifetimes and emissive properties, combined with the design of efficient intramol. Cr(III) ↔ Ln(III) energy transfer processes open attractive perspectives for programming directional light-conversion within these heterometallic mols. Efforts made to address this exciting challenge for both light-sensitization and light-upconversion are discussed in this article.
- 17Bernot, K.; Daiguebonne, C.; Calvez, G.; Suffren, Y.; Guillou, O. A Journey in Lanthanide Coordination Chemistry: From Evaporable Dimers to Magnetic Materials and Luminescent Devices. Acc. Chem. Res. 2021, 54 (2), 427– 440, DOI: 10.1021/acs.accounts.0c0068417https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsFKiuw%253D%253D&md5=855276c6c5033d7d3dbe98d01afa0d73A Journey in Lanthanide Coordination Chemistry: From Evaporable Dimers to Magnetic Materials and Luminescent DevicesBernot, Kevin; Daiguebonne, Carole; Calvez, Guillaume; Suffren, Yan; Guillou, OlivierAccounts of Chemical Research (2021), 54 (2), 427-440CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)A review. Conspectus: Lanthanide ions are prime ingredients for the design of compds., materials, and devices with unique magnetic and optical properties. Accordingly, coordination chem. is one of the best tools for building mol. edifices from these ions because it allows careful control of the ions' environment and of the dimensionality of the final compd. In this Account, the authors review the authors' results on lanthanide-based dimers. A pure fundamental study on lanthanide coordination chem. allows the study of a full continuum of results from the compd. to materials and then to devices. The conversion of mols. into materials is a tricky task because it requires strong mol. robustness toward the surface deposition processes as well as the preservation and detectability of the mol. properties in the material. Addnl., the passage of a material toward a device implies a material with a given function, for example, a tailored response to an external stimulus. To do so, the authors targeted neutral and isolated mols. whose transfer on surfaces by chemi- or physisorption is much easier than that of charged mols. or extended coordination networks. Then, the authors focused on mols. with very strong evaporability to avoid wet chem. deposition processes that are more likely to damage the mols. and/or distort their geometries. The authors thus designed lanthanide dimers based on fluorinated β-diketonates and pyridine-N-oxide ligands. As expected, they show remarkable evaporability but also strong luminescence and interesting magnetic behavior because they behave as single-mol. magnets (SMMs). Ligand substitutions and stoichiometric modifications allow the optimization of the geometric organization of the dimers in the crystal packing as well as their evaporability, SMM behavior, luminescent properties, or their ability to be anchored on surfaces. Most of all, this family of mols. shows a strong ability to form thick films on various substrates. This allows converting these mols. to magnetic materials and luminescent devices. Magnetic materials can be designed by creating thick films of the dimers deposited on gold. These films were designed and studied with the most advanced techniques of on-surface imaging (at. force microscopy, AFM), on-surface physicochem. characterization (XPS, time of flight-secondary ion mass spectroscopy (Tof-SIMS)), and on-surface magnetic study (low-energy muon spin relaxation (LE-μSR)). Contrary to what was previously obsd. on other SMM films, no depth dependence of the SMM behavior was obsd. This means that the dimers do not suffer from the vacuum or substrate interface and behave similarly, whatever their localization. This exceptional magnetic robustness is a key ingredient in the creation of materials for mol. magnetic data storage. Luminescent devices can be obtained by layering mol. films of the dimers with a copper-rich solid-state electrolyte between ITO/Pt electrodes. The electromigration of Cu2+ ions into films of Eu3+, Tb3+, and Dy3+ dimers quenches their luminescence. This luminescence tuning by electromigration is reversible, and this setup can be considered to be a proof of concept of full solid-state luminescent device where reversible coding can be tailored by an elec. field. It is envisioned for optical data storage purposes. In the future, it could also benefit from the SMM properties of the mols. to pave the way toward multifunctional mol. data storage devices.
- 18Cucinotta, G.; Perfetti, M.; Luzon, J.; Etienne, M.; Car, P.-E.; Caneschi, A.; Calvez, G.; Bernot, K.; Sessoli, R. Magnetic Anisotropy in a Dysprosium/DOTA Single-Molecule Magnet: Beyond Simple Magneto-Structural Correlations. Angew. Chem., Int. Ed. 2012, 51 (7), 1606– 1610, DOI: 10.1002/anie.20110745318https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xmt1KksA%253D%253D&md5=836f08c6ae8f81c1240506b8dc5c780fMagnetic Anisotropy in a Dysprosium/DOTA Single-Molecule Magnet: Beyond Simple Magneto-Structural CorrelationsCucinotta, Giuseppe; Perfetti, Mauro; Luzon, Javier; Etienne, Mael; Car, Pierre-Emmanuel; Caneschi, Andrea; Calvez, Guillaume; Bernot, Kevin; Sessoli, RobertaAngewandte Chemie, International Edition (2012), 51 (7), 1606-1610, S1606/1-S1606/11CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Single-crystal magnetic investigations have been shown to be required to study mol. systems that are based on anisotropic lanthanide ions. The detailed exptl. and theor. investigation on one of the most studied lanthanide coordination compds. has provided several key results. The most important one is that simple magnetostructural correlations based on the coordination environment can fail to predict, even approx., the correct magnetic anisotropy of anisotropic lanthanide ions in a low-symmetry environment. Subtle structural details, like the position of hydrogen atoms and the consequent orientation of the nonbonding orbitals of the axial ligand can overcome the symmetry imposed by the coordination polyhedron. The well-resolved luminescence spectra, which allow the energy splitting of the 6H15n multiplet to be detd., have provided precious indications, which confirm that the first excited doublet plays a key role in the magnetization dynamics. .Finally, post Hartree-Fock ab initio calcns. were confirmed to be an invaluable method for the prediction and rationalization of the magnetic anisotropy, provided that subtle structural details are also correctly taken into account. The evaluation of the energy splitting seems, however, even more critically dependent on which structural model and basis sets are used. In modeling the relaxivity effects it is generally assumed that the orientation of the M-Owater of DOTA-like complexes corresponds to the anisotropy axis and that the apical water mols. lie in the cone of highest susceptibility. The authors have shown here that this is probably not the case and we also suspect that the mechanism of contrast in the nuclear relaxation is more complex because the labile water mol. modifies the magnetic anisotropy of the lanthanide ion.
- 19Shannon, R. D. Revised Effective Ionic Radii and Systematic Studies of Interatomic Distances in Halides and Chaleogenides. Acta Crystallogr., A 1976, 32, 751– 767, DOI: 10.1107/S0567739476001551There is no corresponding record for this reference.
- 20Baloch, A. A. B.; Alqahtani, S. M.; Mumtaz, F.; Muqaibel, A. H.; Rashkeev, S. N.; Alharbi, F. H. Extending Shannon’s Ionic Radii Database Using Machine Learning. Phys. Rev. Mater. 2021, 5 (4), 043804 DOI: 10.1103/PhysRevMaterials.5.04380420https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhtVyht73N&md5=acbef731ed4287c03076b96d818d9d7aExtending Shannon's ionic radii database using machine learningBaloch, Ahmer A. B.; Alqahtani, Saad M.; Mumtaz, Faisal; Muqaibel, Ali H.; Rashkeev, Sergey N.; Alharbi, Fahhad H.Physical Review Materials (2021), 5 (4), 043804CODEN: PRMHBS; ISSN:2475-9953. (American Physical Society)In computational material design, ionic radius is one of the most important phys. parameters used to predict material properties. Motivated by the progress in computational materials science and material informatics, we extend the renowned Shannon's table from 475 ions to 987 ions. Accordingly, a rigorous machine learning (ML) approach is employed to extend the ionic radii table using all possible combinations of oxidn. states (OS) and coordination nos. (CN) available in crystallog. repositories. An ionic-radius regression model for Shannon's database is developed as a function of the period no., the valence orbital configuration, OS, CN, and ionization potential. In the Gaussian process regression (GPR) model, the reached R2 accuracy is 99while the root mean square error of radii is 0.0332 Å. The optimized GPR model is then employed for predicting a new set of ionic radii for uncommon combinations of OS and CN extd. by harnessing crystal structures from materials project databases. The generated data are consolidated with the reputable Shannon's data and are made available online in a database repository.
- 21Lundberg, D.; Persson, I.; Eriksson, L.; D’Angelo, P.; De Panfilis, S. Structural Study of the N,N′ -Dimethylpropyleneurea Solvated Lanthanoid(III) Ions in Solution and Solid State with an Analysis of the Ionic Radii of Lanthanoid(III) Ions. Inorg. Chem. 2010, 49 (10), 4420– 4432, DOI: 10.1021/ic100034q21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXkslKlsr4%253D&md5=da9fc684010ea5eefb2635dadcd8df87Structural Study of the N,N'-Dimethylpropyleneurea Solvated Lanthanoid(III) Ions in Solution and Solid State with an Analysis of the Ionic Radii of Lanthanoid(III) IonsLundberg, Daniel; Persson, Ingmar; Eriksson, Lars; D'Angelo, Paola; De Panfilis, SimoneInorganic Chemistry (2010), 49 (10), 4420-4432CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)The structures of the N,N'-dimethylpropyleneurea (dmpu) solvated lanthanoid(III) ions have been studied in dmpu soln. (La-Nd, Sm-Lu) and in solid iodide salts (La-Nd, Sm, Gd-Lu) by extended X-ray absorption fine structure (EXAFS), and single crystal X-ray diffraction (La, Pr, Nd, Gd, Tb, Er, Yb, and Lu); the EXAFS studies were performed on both K and LIII absorption edges. Because of the space-demanding properties of dmpu upon coordination, dmpu solvated metal ions often show coordination nos. lower than those found in corresponding hydrates and solvates of oxygen donor solvents without steric requirements beyond the size of the donor atom. All lanthanoid(III) ions are seven-coordinate in soln., except lutetium(III) which is six-coordinated in regular octahedral fashion, whereas in the solid iodide salts the dmpu solvated lanthanoid(III) ions are all six-coordinate in regular octahedral fashion. A comparison of Ln-O bond lengths in a large no. of lanthanoid(III) complexes with neutral oxygen donor ligands and different configurations shows that the metal ion-oxygen distance is specific for each coordination no. with a narrow bond distance distribution. This also shows that the radius of the coordinated oxygen atom in these compds. can be assumed to be 1.34 Å as proposed for coordinated water, while for ethers such as THF it is somewhat larger. Using this at. radius of oxygen in coordinated water mols., we have calcd. the ionic radii of the lanthanoid(III) ions in four- to nine-coordination and evaluated using the bond lengths reported for homo- and heteroleptic complexes in oxygen donor solvates in soln. and solid state. This yields new and revised ionic radii which in some instances are significantly different from the ionic radii normally referenced in the literature, including interpolated values for the elusive promethium(III) ion.
- 22Seitz, M.; Oliver, A. G.; Raymond, K. N. The Lanthanide Contraction Revisited. J. Am. Chem. Soc. 2007, 129 (36), 11153– 11160, DOI: 10.1021/ja072750f22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXpt1Whsbc%253D&md5=dfdea2fc3d2d5930b26f8df0a6bc004fThe Lanthanide Contraction RevisitedSeitz, Michael; Oliver, Allen G.; Raymond, Kenneth N.Journal of the American Chemical Society (2007), 129 (36), 11153-11160CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)A complete, isostructural series of complexes with La-Lu (except Pm) with the ligand TREN-1,2-HOIQO (I), [M(TREN-1,2-HOIQO-3H)(H2O)]·H2O, was synthesized and structurally characterized by single-crystal x-ray anal. All complexes are 1-dimensional polymeric species in the solid state, with the lanthanide being in an eight-coordinate, distorted trigonal-dodecahedral environment with a donor set of eight unique oxygen atoms. This series constitutes the 1st complete set of isostructural complexes from La-Lu (without Pm) with a ligand of denticity greater than two. The geometric arrangement of the chelating moieties slightly deviates across the lanthanide series, as analyzed by a shape parameter metric based on the comparison of the dihedral angles along all edges of the coordination polyhedron. The apparent lanthanide contraction in the individual Ln-O bond lengths deviates considerably from the expected quadratic decrease that was found previously in a no. of complexes with ligands of low denticity. The sum of all bond lengths around the trivalent metal cation, however, is more regular, showing an almost ideal quadratic behavior across the entire series. The quadratic nature of the lanthanide contraction is derived theor. from Slater's model for the calcn. of ionic radii. The sum of all distances along the edges of the coordination polyhedron show exactly the same quadratic dependence as the Ln-X bond lengths. The universal validity of this coordination sphere contraction, concomitant with the quadratic decrease in Ln-X bond lengths, was confirmed by reexamn. of four other, previously published series of lanthanide complexes. Owing to the importance of multidentate ligands for the chelation of rare-earth metals, this result provides a significant advance for the prediction and rationalization of the geometric features of the corresponding lanthanide complexes, with great potential impact for all aspects of lanthanide coordination.
- 23Peters, J. A.; Djanashvili, K.; Geraldes, C. F. G. C.; Platas-Iglesias, C. The Chemical Consequences of the Gradual Decrease of the Ionic Radius along the Ln-Series. Coord. Chem. Rev. 2020, 406, 213146 DOI: 10.1016/j.ccr.2019.21314623https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXisVKqsbbL&md5=0238ed7d39ff1de80d1d36a3352a16e7The chemical consequences of the gradual decrease of the ionic radius along the Ln-seriesPeters, Joop A.; Djanashvili, Kristina; Geraldes, Carlos F. G. C.; Platas-Iglesias, CarlosCoordination Chemistry Reviews (2020), 406 (), 213146CODEN: CCHRAM; ISSN:0010-8545. (Elsevier B.V.)In the periodical system, the lanthanides (the 15 elements in the periodic table between barium and hafnium) are unique in the sense that their trivalent cations have their valence electrons hidden behind the 5s and 5p electrons. They show a gradual decrease in ionic radius with increasing at. no. (also known as the lanthanide contraction). The resulting steric effects det. to a large extent the geometries of complexes of these ions. Here, we discuss these effects, particularly upon the properties of the complexes in aq. soln., for selected families of Ln3+-complexes of oxycarboxylate and aminocarboxylate ligands. The phys. properties of the cations are very different, which is very useful for the elucidation of the configuration, conformation and the dynamics of the complexes by X-ray techniques, NMR spectroscopy, and optical techniques. Often the structural anal. is assisted by computational methods.
- 24Jordan, R. B. Lanthanide Contraction: What Is Normal?. Inorg. Chem. 2023, 62, 3715– 3721, DOI: 10.1021/acs.inorgchem.2c0367424https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3sXjsF2lt7Y%253D&md5=7a8d5a6119851d88795feda850cdc1a2Lanthanide Contraction: What is Normal?Jordan, Robert B.Inorganic Chemistry (2023), 62 (9), 3715-3721CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)Renewed interest in lanthanide contraction results from its possible effect on the properties and applications of Ln(III) compds. and the theory related to these issues. To understand this effect, it is important to know what is a normal dependence of the contraction on the no. of 4f electrons, n. The normal trend is based on recent values of ionic radii that have a linear dependence on n for coordination nos. (CNs) of 6, 8, and 9. If the normal trend is not followed, then some other interactions in the system are affecting the extent of contraction. However, the suggestion that the variation is curved and fitted by a quadratic function has become popular in recent years. This report examines the Ln(III)-to-ligand atom distances for coordination compds. with CNs of 6-9 and the nitrides and phosphides. Least-squares fits to the linear and quadratic models are applied to all of the bond distances to det. when a quadratic model is justified. The result is that complex systems show a mixt. of linear and quadratic dependencies when individual bond distances are considered and that the linear model is most common and representative of the true lanthanide contraction.
- 25Bart, S. C. What Is the “Lanthanide Contraction”?. Inorg. Chem. 2023, 62, 3713– 3714, DOI: 10.1021/acs.inorgchem.3c0044025https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3sXjsF2lurk%253D&md5=fdd9d1aef33abb90594b76a1216fcc50What is the "Lanthanide Contraction"?Bart, Suzanne C.Inorganic Chemistry (2023), 62 (9), 3713-3714CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)There is no expanded citation for this reference.
- 26Fyfe, W. S. The Problem of Bond Type. Am. Mineral. 1954, 39, 991– 100426https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaG2MXotFeisg%253D%253D&md5=a3d8a1d9021b4583b8f77236ae4f7187The problem of bond typeFyfe, W. S.American Mineralogist (1954), 39 (), 991-1004CODEN: AMMIAY; ISSN:0003-004X.cf. C.A. 47, 11868g. Consideration of electronegativities is inadequate for quant. evaluation of the proportions of ionic and covalent bonding in a compd. The overlap integrals give better values, as illustrated for the alkali halides, and by comparison of Si-O and C-O bonds.
- 27Kawabe, I. Lanthanide Tetrad Effect in the Ln3+ Ionic Radii and Refined Spin-Pairing Energy Theory. Geochem. J. 1992, 26 (6), 309– 335, DOI: 10.2343/geochemj.26.30927https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXmsFKrt7c%253D&md5=7830517b8ce171b7305a975dee1a9317Lanthanide tetrad effect in the Ln3+ ionic radii and refined spin-pairing energy theoryKawabe, IwaoGeochemical Journal (1992), 26 (6), 309-35CODEN: GEJOBE; ISSN:0016-7002.The refined spin-pairing energy theory (RSPET) has been improved in order to understand quant. the tetrad or double-double effects recognized in the Ln3+ ionic radii. Since the ionic radii have been detd. from the lattice consts. and structural parameters of LnO1.5 and LnF3, the lattice energies of the compds. and the enthalpy difference of ΔHf°(LnF3) - ΔHf°(LnO1.5) have been examd. by the improved RSPET. The RSPET parameters for the lowest levels of 4fq electronic configurations strongly depend upon the effective nuclear charge (Z*). Such effects due to Z* have been taken into account. This made it possible to sep. the variations in the lattice energies and the enthalpy difference across the Ln3+ series into the following two parts: (1) the large variation as a smooth function of q (the lanthanide contraction trend), and (2) the small zig-zag variation referred to the tetrad or double-double effect. The lattice energy of LnO1.5 and ΔHf°(LnF3) - ΔHf°(LnO1.5) exhibit upward concave tetrad curves in their plots against q of Ln3+. The tetrad effect in the lattice energy of LnF3 is less conspicuous. This means that the Racah parameters for Ln3+ decrease very slightly in going from the gaseous free Ln3+ to LnF3, and then decrease greatly to LnO1.5, in accordance with the nephelauxetic series. The differences in Racah parameters between LnF3 and LnO1.5 have been estd. from ΔHf°(LnF3) - ΔHf°(LnO1.5) by means of an inversion technique based on the improved RSPET. The RSPET results for the thermochem. data are consistent with the careful spectroscopic detns. of Racah parameters for NdF3 and NdO1.5. Both the tetrad effect and the smooth lanthanide contraction seen in the Ln3+ ionic radii can be interpreted in terms of the quantum mech. energetics of 4f electrons.
- 28Gibbs, G. V.; Tamada, O.; Boisen, M. B., Jr. Atomic and Ionic Radii: A Comparison with Radii Derived from Electron Density Distributions. Phys. Chem. Miner. 1997, 24 (6), 432– 439, DOI: 10.1007/s00269005005728https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2sXltlaitrs%253D&md5=c155ab05be834f2dfee8af72a62c03c5Atomic and ionic radii: a comparison with radii derived from electron density distributionsGibbs, G. V.; Tamada, Osamu; Boisen, M. B., Jr.Physics and Chemistry of Minerals (1997), 24 (6), 432-439CODEN: PCMIDU; ISSN:0342-1791. (Springer)The bonded radii of anions obtained in topol. analyses of theor. and exptl. electron d. distributions differ from at., ionic and crystal radii in that oxide-, fluoride-, nitride- and sulfide-anion radii are not const. for a given coordination no. They vary in a regular way with bond length and the electronegativity of the cation to which they are bonded, exhibiting radii close to at. radii when bonded to a highly electroneg. cation and radii close to ionic radii when bonded to a highly electropos. cation. The electron d. distributions show that anions are not spherical but exhibit several different radii in different bonded directions. The bonded radii of cations correlate with ionic and at. radii. But unlike ionic radii, the bonded radius of a cation shows a relatively small increase in value with an increase in coordination no. In contrast to at. and ionic radii, the bonded radius of an ion in a crystal or mol. can be used as a reliable and well-defined est. of its radius in the direction of its bonds.
- 29Gibbs, G. V.; Ross, N. L.; Cox, D. F.; Rosso, K. M.; Iversen, B. B.; Spackman, M. A. Bonded Radii and the Contraction of the Electron Density of the Oxygen Atom by Bonded Interactions. J. Phys. Chem. A 2013, 117 (7), 1632– 1640, DOI: 10.1021/jp310462g29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXnvVGmsw%253D%253D&md5=d147f4dbd5d6d4ec63e980b51cc73dfcBonded Radii and the Contraction of the Electron Density of the Oxygen Atom by Bonded InteractionsGibbs, Gerald V.; Ross, Nancy L.; Cox, David F.; Rosso, Kevin M.; Iversen, Bo B.; Spackman, Mark A.Journal of Physical Chemistry A (2013), 117 (7), 1632-1640CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)The bonded radii for more than 700 bonded pairs of atoms, comprising more than 50 oxide crystals, extd. from exptl. and theor. electron d. distributions, are averaged and compared with the ionic radii for first, second, and third row atoms. At odds with the assumption of a fixed ionic radius of 1.40 Å for the oxide anion, the bonded radius for the anion, rb(O), decreases systematically from 1.40 to 0.65 Å as the electron d. distribution of the atom is progressively polarized and contracted by its bonded interactions. The radii for the more electropos. metal atoms agree with the ionic radii when the electron d. distribution of the anion is largely unpolarized by its bonded interactions. However, those for the more electroneg. metal atoms are progressively larger than the ionic radii as the electron d. distribution of the anion is progressively polarized and contracted along the bond vectors with decreasing bond length. The progressive decrease of rb(O) indicates that the compilation of sets of ionic radii, based on a fixed radius for the oxide anion, is problematic and impacts the accuracy of the ionic radii for the metal atoms. The assumption of a fixed radius for the anion, made in the derivation of sets of radii, not only results in unrealistic neg. ionic radii for the more electroneg. atoms but also in ionic radii that are as much as 0.5 Å smaller than the bonded radii, particularly for the more electroneg. M atoms. The lack of agreement between the ionic and the bonded radii for the more shared bonded interactions is ascribed to the progressive increase in the polarization and contraction of the electron d. of the oxide anion by the bonded interactions with a concomitant decrease in the radius of the anion, a factor that was largely neglected in the compilation of the ionic radii for fluoride, oxide, sulfide, and nitride crystals. The close agreement of the bonded radii and procrystal bonded radii is consistent with the argument that the chem. forces that govern the electron d. distributions and bonded radii are largely at. in nature, resulting in comparable electron d. distributions.
- 30Rahm, M.; Hoffmann, R.; Ashcroft, N. W. Atomic and Ionic Radii of Elements 1–96. Chem. – Eur. J. 2016, 22 (41), 14625– 14632, DOI: 10.1002/chem.20160294930https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtlyktbnP&md5=e2f480081daf268668503d6891189fc7Atomic and Ionic Radii of Elements 1-96Rahm, Martin; Hoffmann, Roald; Ashcroft, N. W.Chemistry - A European Journal (2016), 22 (41), 14625-14632CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Atomic and cationic radii have been calcd. for the first 96 elements, together with selected anionic radii. The metric adopted is the av. distance from the nucleus where the electron d. falls to 0.001 electrons per bohr3, following earlier work by Boyd. Our radii are derived using relativistic all-electron d. functional theory calcns., close to the basis set limit. They offer a systematic quant. measure of the sizes of non-interacting atoms, commonly invoked in the rationalization of chem. bonding, structure, and different properties. Remarkably, the at. radii as defined in this way correlate well with van der Waals radii derived from crystal structures. A rationalization for trends and exceptions in those correlations is provided.
- 31Liu, J.-B.; Schwarz, W. H. E.; Li, J. On Two Different Objectives of the Concepts of Ionic Radii. Chem. – Eur. J. 2013, 19 (44), 14758– 14767, DOI: 10.1002/chem.20130091731https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsF2nu7%252FO&md5=b6169c1ab18c468efce844b3ee904eb9On Two Different Objectives of the Concepts of Ionic RadiiLiu, Jian-Biao; Schwarz, W. H. Eugen; Li, JunChemistry - A European Journal (2013), 19 (44), 14758-14767CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Exptl. and theor. derived interat. distances (D) and ionic radii (R) of more than a hundred monomeric (AX), dimeric (A2X2, ABXY), and cryst. ([AX]) alkali halide species (A=Li, Na, K, Rb, Cs, Fr; X=H, F, Cl, Br, I, At) have been analyzed. Chemists use the word "at. radius" for two antithetic concepts. Let DCiEE'jj' be the "billion" of distances i between two adjacent atoms in the millions of known compds. C from a hundred different elements E in bonding states j. The common chem. aim is partitioning D approx. into increments REj + RE'j'. This can be achieved with a few (say <thousand) predictive consts. REj. An antipodal aim is specifying in hindsight an electron d. feature in the "billion" of different bonds i, by partitioning them into "two billions" of exact bonded radii RECi + RE'Ci. The const. incremental and the variable bonded radii concepts with the same generic name are useful in different fields of research. Different concepts should be well distinguished, since they have different meaning, different numerical values, and different purposes.
- 32Cordero, B.; Gómez, V.; Platero-Prats, A. E.; Revés, M.; Echeverría, J.; Cremades, E.; Barragán, F.; Alvarez, S. Covalent Radii Revisited. Dalton Trans. 2008, 21, 2832– 2838, DOI: 10.1039/b801115jThere is no corresponding record for this reference.
- 33Pyykkö, P.; Atsumi, M. Molecular Single-Bond Covalent Radii for Elements 1–118. Chem. – Eur. J. 2009, 15 (1), 186– 197, DOI: 10.1002/chem.200800987There is no corresponding record for this reference.
- 34Pyykkö, P. Additive Covalent Radii for Single-, Double-, and Triple-Bonded Molecules and Tetrahedrally Bonded Crystals: A Summary. J. Phys. Chem. A 2015, 119 (11), 2326– 2337, DOI: 10.1021/jp506581934https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhsVektrzI&md5=6c1fec0c71e630c9c87aee775ce8ca9eAdditive Covalent Radii for Single-, Double-, and Triple-Bonded Molecules and Tetrahedrally Bonded Crystals: A SummaryPyykko, PekkaJournal of Physical Chemistry A (2015), 119 (11), 2326-2337CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)A review. The recent fits of additive covalent radii RAB = rA + rB for the title systems are reviewed and compared with alternative systems of radii by other authors or with further exptl. data. The agreement of the predicted R with expt. is good, provided that the A-B bond is not too ionic, or the coordination nos. of the two atoms too different from the original input data, used in the fit. Bonds between transition metals and halides are not included in the single-bond set, because of their partial multiple-bond character.
- 35Gunnlaugsson, T.; Leonard, J. P.; Mulready, S.; Nieuwenhuyzen, M. Three Step vs One Pot Synthesis and X-Ray Crystallographic Investigation of Heptadentate Triamide Cyclen (1,4,7,10-Tetraazacyclododecane) Based Ligands and Some of Their Lanthanide Ion Complexes. Tetrahedron 2004, 60 (1), 105– 113, DOI: 10.1016/j.tet.2003.10.08635https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXpslOjtLg%253D&md5=bf5dff38e1edf05f8d23cbb11b72d1c6Three step vs. one pot synthesis and X-ray crystallographic investigation of heptadentate triamide cyclen (1,4,7,10-tetraazacyclododecane) based ligands and some of their lanthanide ion complexesGunnlaugsson, Thorfinnur; Leonard, Joseph P.; Mulready, Sinead; Nieuwenhuyzen, MarkTetrahedron (2004), 60 (1), 105-113CODEN: TETRAB; ISSN:0040-4020. (Elsevier Science B.V.)The synthesis of several lanthanide complexes from the tris alkylated cyclen (1,4,7,10-tetraazacyclododecane) ligands (I, R = Me, 1;R = H, 2) is described. The prepn. of 1 and 2 were studied by two different synthetic routes (Methods 1 and 2). The 1st of these involves the mono protection of cyclen using 4-methoxyphenylsulfonyl chloride, followed by alkylation of the remaining three secondary amines of cyclen, and deprotection using solvated Na(s). Using this approach only 1 was successfully formed. The x-ray crystal structure of the intermediate, (II = 9) and the corresponding La(III) complex, 9·La is presented. The 2nd method involved the direct synthesis of the two ligands in a single step. The x-ray crystallog. of the Eu(III) complex of one of these ligands is presented. Whereas, Method 1 yielded the product 1 in high purity, but in low overall yield, Method 2 gave higher yields for both ligands (∼50% for both).
- 36Amin, S.; Morrow, J. R.; Lake, C. H.; Churchill, M. R. Lanthanide(III) Tetraamide Macrocyclic Complexes as Synthetic Ribonucleases: Structure and Catalytic Properties of[La(Tcmc)(CF3SO3)(EtOH)](CF3SO3)2. Angew. Chem., Int. Ed. 1994, 33 (7), 773– 775, DOI: 10.1002/anie.199407731There is no corresponding record for this reference.
- 37Franklin, S. J.; Raymond, K. N. Solution Structure and Dynamics of Lanthanide Complexes of the Macrocyclic Polyamino Carboxylate DTPA-Dien. NMR Study and Crystal Structures of the Lanthanum(III) and Europium(III) Complexes. Inorg. Chem. 1994, 33 (25), 5794– 5804, DOI: 10.1021/ic00103a02937https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXntFCnurk%253D&md5=1482406696ff4ac0c56f722b8f5c6209Solution Structure and Dynamics of Lanthanide Complexes of the Macrocyclic Polyamino Carboxylate DTPA-dien. NMR Study and Crystal Structures of the Lanthanum(III) and Europium(III) ComplexesFranklin, Sonya J.; Raymond, Kenneth N.Inorganic Chemistry (1994), 33 (25), 5794-804CODEN: INOCAJ; ISSN:0020-1669.An 18-membered macrocyclic DTPA-bis(amide) ligand (I; DTPA = diethylenetriaminepentaacetic acid) contg. a heteroatom in the amide link was prepd. via the condensation of DTPA-dianhydride and diethylenetriamine. The soln. structures of the two isomeric pairs present in the Ln(III) complexes of DTPA-dien were studied by 1H NMR. One enantiomeric pair exhibits slow exchange on the NMR time scale at low temps. (0-25°) and dynamic behavior at higher temps. The other isomeric pair exhibits an unusual static behavior; exchange remains slow even at 95°. Peak assignments for the Eu(DTPA-dien) spectra are given based on deuteration studies, 2-dimensional COSY spectroscopy, and 2-dimensional EXSY spectroscopy. 2D EXSY spectroscopy at several temps. and mixing times showed that ΔG⧧299 for the dynamic isomerization is 57.5 ± 0.3 kJ/mol, and that the dynamic isomer is an intermediate for the static isomerization, which occurs with a change in backbone amine chirality. The structures of the La(III) and Eu(III) DTPA-dien complexes were detd. by x-ray anal. [La(DTPA-dienH+)H2O]2(CF3SO3-)2·18H2O crystallizes as a carboxylate-bridged dimer about a center of inversion in the orthorhombic space group Pbca with a 12.626(2), b 21.405(3), c 26.422(9) Å, and Z = 8. Each La ion is 11-coordinate with octadentate ligand coordination, an η2 bridging carboxylate, and one H2O. [Eu(DTPA-dienH+)]4(CF3SO3-)4·6NaCF3SO3·20H2O crystallizes as a carboxylate-bridged tetramer with two crystallog. independent Eu(III) positions (Z = 8 for each) in the monoclinic space group C2/c: a 30.94(1), b 23.456(3), c 22.611(4) Å, β 105.78(2)°. The coordination geometries about Eu1 and Eu2 are nearly identical and are described as a nine-coordinate tricapped trigonal prism with octadentate ligand coordination plus an η1 bridging carboxylate. The tendency to oligomerize is attributed to the constraints imposed by the macrocycle and the H bonding available with the link heteroatom. The structural differences between the two complexes are attributed to a difference in La(III) and Eu(III) ionic size. The soln. structure of the dynamic isomer is the same as the monomer unit of the crystal structures, and the static isomer is similar, save for a change in one terminal backbone nitrogens' chirality.
- 38Nakai, H.; Nonaka, K.; Goto, T.; Seo, J.; Matsumoto, T.; Ogo, S. A Macrocyclic Tetraamine Bearing Four Phenol Groups: A New Class of Heptadentate Ligands to Provide an Oxygen-Sensitive Luminescent Tb(iii) Complex with an Extendable Phenol Pendant Arm. Dalton Trans. 2015, 44 (24), 10923– 10927, DOI: 10.1039/C5DT00816F38https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXnvFWguro%253D&md5=12d6f49a8c5eb0f1586e6ba37dc2af91A macrocyclic tetraamine bearing four phenol groups: a new class of heptadentate ligands to provide an oxygen-sensitive luminescent Tb(III) complex with an extendable phenol pendant armNakai, Hidetaka; Nonaka, Kyoshiro; Goto, Takahiro; Seo, Juncheol; Matsumoto, Takahiro; Ogo, SeijiDalton Transactions (2015), 44 (24), 10923-10927CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)This paper presents a 1,4,7,10-teraazacyclododecane-based tetrakis-phenol (H4L) as a protonated ligand precursor and its oxygen-sensitive luminescent terbium(III) complex with an extendable phenol pendant arm (Φ = 0.91 under N2, Φ = 0.031 under air), in which the potentially N4O4-octadentate ligand unprecedentedly coordinates to the Tb3+ ion in a N4O3-heptadentate fashion (1, TbL).
- 39Wen, H.-R.; Zhang, J.-L.; Liang, F.-Y.; Yang, K.; Liu, S.-J.; Liu, C.-M. Multifunctional Lanthanide Complexes Based on Tetraazacyclolamidophenol Ligand with Field-Induced Slow Magnetic Relaxation, Luminescent and SHG Properties: Multifunctional Lanthanide Complexes Based on Tetraazacyclolamidophenol Ligand with Field-Induced Slow Magnetic Relaxation, Luminescent and SHG Proper. Eur. J. Inorg. Chem. 2019, 2019 (10), 1406– 1412, DOI: 10.1002/ejic.20180149239https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXjvFWgu7Y%253D&md5=ab1bfc71f75d61bb6b4b00adc391323fMultifunctional Lanthanide Complexes Based on Tetraazacyclolamidophenol Ligand with Field-Induced Slow Magnetic Relaxation, Luminescent and SHG PropertiesWen, He-Rui; Zhang, Jia-Li; Liang, Fu-Yong; Yang, Kai; Liu, Sui-Jun; Liu, Cai-MingEuropean Journal of Inorganic Chemistry (2019), 2019 (10), 1406-1412CODEN: EJICFO; ISSN:1434-1948. (Wiley-VCH Verlag GmbH & Co. KGaA)Two multifunctional lanthanide complexes, [Dy(HL)]·MeOH (1) and [Er(HL)]·MeOH (2), [H4L = N,N',N'',N'''-tetra(3,5-dimethyl-2-Hydroxybenzyl)-1,4,7,10-tetraazacyclododecane] were synthesized and structurally characterized. Complexes 1 and 2 are isomorphic and crystallize in the noncentrosym. orthorhombic space group Pca21. Their structure consists of one seven-coordinated LnIII ion with the coordination geometry of trigonal prism, one HL3- ligand and one lattice MeOH mol. They exhibit 2nd-harmonic generation (SHG) effect. Complex 1 displays strong fluorescent emissions, which are typical narrow emission bands of lanthanide ions. Complex 1 features field-induced slow magnetic relaxation behavior. Therefore, complex 1 may be a potential multifunctional mol. material.
- 40Urbanovský, P.; Kotek, J.; Císařová, I.; Hermann, P. The Solid-State Structures and Ligand Cavity Evaluation of Lanthanide(III) Complexes of a DOTA Analogue with a (Dibenzylamino)Methylphosphinate Pendant Arm. Dalton Trans. 2020, 49 (5), 1555– 1569, DOI: 10.1039/C9DT04056K40https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitleju7zJ&md5=58cf71adce2c996b34b6c6c6e7dbfdb5The solid-state structures and ligand cavity evaluation of lanthanide(III) complexes of a DOTA analogue with a (dibenzylamino)methylphosphinate pendant armUrbanovsky, Peter; Kotek, Jan; Cisarova, Ivana; Hermann, PetrDalton Transactions (2020), 49 (5), 1555-1569CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)A series of lanthanide(III) complexes of a monophosphinate analog of H4dota, 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic-10-methyl[(N,N-dibenzylamino)methyl]phosphinic acid (H4do3apDBAm = H4L1), were prepd. and their solid-state structures were studied using single-crystal X-ray diffraction. In all structures, the ligand anion was octadentately coordinated to the Ln(III) or Sc(III) ions similarly to other DOTA-like ligands, i.e. forming parallel N4- and O4-planes. The lighter lanthanide(III) complexes (till dysprosium) were nonacoordinated in the twisted square-antiprismatic (TSA) configuration with the apical coordination of water mols. or oxygen atoms from the neighboring complex unit. The heavier lanthanide(III) complexes (from terbium) were found as the "anhyd." octacoordinated twisted square-antiprismatic (TSA') isomer. For the terbium(III) ion, both forms were structurally characterized. The structural data of the Ln(III)-H4L1 complexes and complexes of several related DOTA-like ligands were analyzed. It clearly showed that the structural parameters for the square-antiprismatic (SA) isomers were clustered in a small range while those for the TSA/TSA' isomers were significantly more spread. The anal. also gave useful information about the influence of various pendant arms on the structure of the complexes of the DOTA-like ligands. The twist angle (torsion) of the chelate ring contg. a larger phosphorus atom was similar to those of the remaining three acetate pendants. It led to a larger sepn. of the N4···O4 planes and to smaller trans-O-Ln-O angles than the parameters found in the complexes of H4dota and its tetraamide derivs. dotam(R). It resulted in a relatively long bond between the metal ion and the coordinated water mol. It led, together with the neg. charge of the oxygen atoms forming the O4-plane, to an extremely fast water exchange rate reported for the Gd(III)-H4L1 complex and, generally, to a fast water exchange of Gd(III) complexes with the monophosphorus acid analogs of H4dota, H5do3ap/H4do3apR.
- 41Woods, M.; Payne, K. M.; Valente, E. J.; Kucera, B. E.; Young, V. G. Crystal Structures of DOTMA Chelates from Ce3+ to Yb3+: Evidence for a Continuum of Metal Ion Hydration States. Chem. – Eur. J. 2019, 25 (42), 9997– 10005, DOI: 10.1002/chem.20190206841https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtlaqtLfJ&md5=a9926b84e88d9e64a38fd241d90ffabcCrystal Structures of DOTMA Chelates from Ce3+ to Yb3+: Evidence for a Continuum of Metal Ion Hydration StatesWoods, Mark; Payne, Katherine M.; Valente, Edward J.; Kucera, Benjamin E.; Young, Victor G. Jr.Chemistry - A European Journal (2019), 25 (42), 9997-10005CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)The crystal structures of chelates formed between each stable paramagnetic lanthanide ion and the octadentate polyamino carboxylate ligand DOTMA are described. A total of 23 individual chelates structures were obtained; in each chelate the coordination geometry around the metal ion is best described as a twisted square antiprism (torsion angle -25.0°--31.4°). Despite the uniformity of the general coordination geometry provided by the DOTMA ligand, there is a considerable variation in the hydration state of each chelate. The early Ln3+ chelates are assocd. with a single inner sphere water mol.; the Ln-OH2 interaction is remarkable for being very long. After a clear break at gadolinium, the no. of chelates in the unit cell that have a water mol. interacting with the Ln3+ decreases linearly until at Tm3+ no water is found to interact with the metal ion. The Ln-OH2 distance obsd. in the chelates of the later Ln3+ ions are also extremely long and increase as the ions contract (2.550-2.732 Å). No clear break between hydrated and dehydrated chelates is obsd.; rather this series of chelates appear to represent a continuum of hydration states in which the ligand gradually closes around the metal ion as its ionic radius decreases (with decreased hydration) and the metal drops down into the coordination cage.
- 42Starynowicz, P. Complexes of Divalent Europium with Dotp and Dotpph. New J. Chem. 2021, 45 (13), 5879– 5889, DOI: 10.1039/D1NJ00393C42https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXltlegurw%253D&md5=3b02b9aa7253fd7168d0a9b84964056fComplexes of divalent europium with dotp and dotpphStarynowicz, PrzemyslawNew Journal of Chemistry (2021), 45 (13), 5879-5889CODEN: NJCHE5; ISSN:1144-0546. (Royal Society of Chemistry)Two complexes of divalent europium, with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylene phosphonate) (dotp) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylene P-phenylphosphinate) (dotpph), were obtained by electrochem. synthesis. In both compds., the Eu2+ cation is 8-coordinate, surrounded by 4 oxygen atoms from phosphonate or phosphinate groups and 4 nitrogen atoms. The complex with dotp shows green luminescence at 77 K, while in the dotpph complex the emission is almost completely quenched. The TD DFT calcns. suggest that in both complexes the emission is of anomalous character: s → f for the first complex and π* → f for the other. Polarog. half-wave potentials of both complexes are similar to those of Eu aminopolycarboxylates. The Eu-O bonds, analyzed using topol. methods, are ionic; the Eu-N bonds in the first complex show a certain degree of covalency, while in the other one they are ionic.
- 43Basal, L. A.; Bailey, M. D.; Romero, J.; Ali, M. M.; Kurenbekova, L.; Yustein, J.; Pautler, R. G.; Allen, M. J. Fluorinated EuII -Based Multimodal Contrast Agent for Temperature- and Redox-Responsive Magnetic Resonance Imaging. Chem. Sci. 2017, 8 (12), 8345– 8350, DOI: 10.1039/C7SC03142D43https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhslantLvJ&md5=1dfe4497908d97d5a81bcc698185b607Fluorinated EuII-based multimodal contrast agent for temperature- and redox-responsive magnetic resonance imagingBasal, Lina A.; Bailey, Matthew D.; Romero, Jonathan; Ali, Meser M.; Kurenbekova, Lyazat; Yustein, Jason; Pautler, Robia G.; Allen, Matthew J.Chemical Science (2017), 8 (12), 8345-8350CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)Magnetic resonance imaging (MRI) using redox-active, EuII-contg. complexes is one of the most promising techniques for noninvasively imaging hypoxia in vivo. In this technique, pos. (T1-weighted) contrast enhancement persists in areas of relatively low oxidizing ability, such as hypoxic tissue. Herein, we describe a fluorinated, EuII-contg. complex in which the redox-active metal is caged by intramol. interactions. The position of the fluorine atoms enables temp.-responsive contrast enhancement in the reduced form of the contrast agent and detection of the oxidized contrast agent via MRI in vivo. Pos. contrast is obsd. in 1H-MRI with Eu in the +2 oxidn. state, and chem. exchange satn. transfer and 19F-MRI signal are obsd. with Eu in the +3 oxidn. state. Contrast enhancement is controlled by the redox state of Eu, and modulated by the fluorous interactions that cage a bound water mol. reduce relaxivity in a temp.-dependent fashion. Together, these advancements constitute the first report of in vivo, redox-responsive imaging using 19F-MRI.
- 44Burai, L.; Tóth, É.; Seibig, S.; Scopelliti, R.; Merbach, A. E. Solution and Solid-State Characterization of EuII Chelates: A Possible Route Towards Redox Responsive MRI Contrast Agents. Chem. – Eur. J. 2000, 6 (20), 3761– 3770, DOI: 10.1002/1521-3765(20001016)6:20<3761::AID-CHEM3761>3.0.CO;2-644https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXns1Cmu7c%253D&md5=8da82fdac83df748b26a5d45c31b9872Solution and solid-state characterization of EuII chelates: a possible route towards redox responsive MRI contrast agentsBurai, Laszlo; Toth, Eva; Seibig, Sabine; Scopelliti, Rosario; Merbach, Andre E.Chemistry - A European Journal (2000), 6 (20), 3761-3770CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH)We report the first solid state X-ray crystal structure for a EuII chelate, [C(NH2)3]3[EuII(DTPA)(H2O)]·8H2O, in comparison with those for the corresponding Sr analog, [C(NH2)3]3[Sr(DTPA)(H2O)]·8H2O and for [Sr(ODDA)]·8H2O (DTPA5- = diethylenetriamine-N,N,N',N",N"-pentaacetate, ODDA2- = 1,4,10,13-tetraoxa-7,16-diaza-cyclooctadecane-7,16-diacetate). The two DTPA complexes are isostructural due to the similar ionic size and charge of Sr2+ and Eu2+. The redox stability of [EuII(ODDA)(H2O)] and [EuII(ODDM)]2- complexes has been investigated by cyclovoltammetry and UV/Vis spectrophotometry (ODDM4- = 1,4,10,13-tetraoxa-7,16-diaza-cyclooctadecane-7,16-dimalonate). The macrocyclic complexes are much more stable against oxidn. than [EuII(DTPA)(H2O)]3- (the redox potentials are E1/2 = -0.82 V, -0.92 V, and -1.35 V vs. Ag/AgCl electrode for [EuIII/II(ODDA)(H2O)], [EuIII/II(ODDM)], and [EuIII/II(DTPA)(H2O)], resp., compared with -0.63 V for EuIII/II aqua). The thermodn. stability consts. of [EuII(ODDA)(H2O)], [EuII(ODDM)]2-, [Sr(ODDA)(H2O)], and [Sr(ODDM)]2- were also detd. by pH potentiometry. They are slightly higher for the EuII complexes than those for the corresponding Sr analogs (logKML = 9.85, 13.07, 8.66, and 11.34 for [EuII(ODDA)(H2O)], [EuII(ODDM)]2-, [Sr(ODDA)(H2O)], and [Sr(ODDM)]2-, resp., 0.1 M (CH3)4NCl). The increased thermodn. and redox stability of the EuII complex formed with ODDA as compared with the traditional ligand DTPA can be of importance when biomedical application is concerned. A variable-temp. 17O-NMR and 1H-nuclear magnetic relaxation dispersion (NMRD) study has been performed on [EuII(ODDA)(H2O)] and [EuII(ODDM)]2- in aq. soln. [EuII(ODDM)]2- has no inner-sphere water mol. which allowed us to use it as an outer-sphere model for [EuII(ODDA)(H2O)]. The water exchange rate (kex298 = 0.43 × 109 s-1) is one third of that obtained for [EuII(DTPA)(H2O)]3-. The variable pressure 17O-NMR study yielded a neg. activation vol., Δν = -3.9 cm3mol-1; this indicates associatively activated water exchange. This water exchange rate is in the optimal range to attain max. proton relaxivities, which are, however, strongly limited by the fast rotation of the small mol. wt. complex.
- 45Dovrat, G.; Pevzner, S.; Maimon, E.; Vainer, R.; Iliashevsky, O.; Ben-Eliyahu, Y.; Moisy, P.; Bettelheim, A.; Zilbermann, I. DOTP versus DOTA as Ligands for Lanthanide Cations: Novel Structurally Characterized CeIV and CeIII Cyclen-Based Complexes and Clusters in Aqueous Solutions. Chem. – Eur. J. 2022, 28 (61), e20221868 DOI: 10.1002/chem.202201868There is no corresponding record for this reference.
- 46Rodríguez-Rodríguez, A.; Regueiro-Figueroa, M.; Esteban-Gómez, D.; Rodríguez-Blas, T.; Patinec, V.; Tripier, R.; Tircsó, G.; Carniato, F.; Botta, M.; Platas-Iglesias, C. Definition of the Labile Capping Bond Effect in Lanthanide Complexes. Chem. – Eur. J. 2017, 23 (5), 1110– 1117, DOI: 10.1002/chem.20160439046https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitFahs73O&md5=2a8dab208430d2d7386be1931eb5a126Definition of the Labile Capping Bond Effect in Lanthanide ComplexesRodriguez-Rodriguez, Aurora; Regueiro-Figueroa, Martin; Esteban-Gomez, David; Rodriguez-Blas, Teresa; Patinec, Veronique; Tripier, Raphael; Tircso, Gyula; Carniato, Fabio; Botta, Mauro; Platas-Iglesias, CarlosChemistry - A European Journal (2017), 23 (5), 1110-1117CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Two macrocyclic ligands contg. a cyclen unit, a Me group, a picolinate arm, and two acetate pendant arms attached to two nitrogen atoms of the macrocycle either in trans (1,7-H3Medo2 ampa = 2,2'-(7-((6-carboxypyridin-2-yl)methyl)-10-methyl-1,4,7,10-tetraazacyclododecane-1,4-diyl)diacetic acid) or in cis (1,4-H3Medo2 ampa) positions are reported. These ligands provide eight-coordination to the Ln3+ ions, leaving a coordination position available for a water mol. that occupies a capping position in the twisted square antiprismatic polyhedron (1,4-H3Medo2 ampa) or one of the positions of the square antiprism (1,7-H3Medo2 ampa). The charge neutral [Gd(1,7-Medo2 ampa)] complex presents an unprecedentedly low water-exchange rate (kex298=8.8 × 103 s-1), whereas water exchange in [Gd(1,4-Medo2 ampa)] is three orders of magnitude faster (kex298=6.6 × 106 s-1). These results showcase the labile capping bond phenomenon: A ligand occupying a capping position is hindered by the environment and thus is intrinsically labile.
- 47Caravan, P.; Esteban-Gómez, D.; Rodríguez-Rodríguez, A.; Platas-Iglesias, C. Water Exchange in Lanthanide Complexes for MRI Applications. Lessons Learned over the Last 25 Years. Dalton Trans. 2019, 48 (30), 11161– 11180, DOI: 10.1039/C9DT01948K47https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtF2nt7fF&md5=02e06253fa7c2f3ca51f0a3dfd289f65Water exchange in lanthanide complexes for MRI applications. Lessons learned over the last 25 yearsCaravan, Peter; Esteban-Gomez, David; Rodriguez-Rodriguez, Aurora; Platas-Iglesias, CarlosDalton Transactions (2019), 48 (30), 11161-11180CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)The water exchange rates of water mols. coordinated to the metal ion in lanthanide complexes have been profusely investigated during the last 25 years, esp. in the case of Gd3+ and Eu3+ complexes. This is mainly related to the important application of some Gd3+ complexes as contrast agents in magnetic resonance imaging (MRI), and the intensive investigation of Eu3+ complexes as contrast agent candidates providing contrast through the chem. exchange satn. transfer mechanism (CEST). Both applications require a fine tunning of the exchange rate of the coordinated water mol. to yield optimal response. Herein we review the progress made in this field to control water exchange in a rational way through ligand design, providing relationships between the obsd. trends, the structures of the complexes and the mechanisms responsible for the water exchange reaction.
- 48Garda, Z.; Nagy, V.; Rodríguez-Rodríguez, A.; Pujales-Paradela, R.; Patinec, V.; Angelovski, G.; Tóth, É.; Kálmán, F. K.; Esteban-Gómez, D.; Tripier, R.; Platas-Iglesias, C.; Tircsó, G. Unexpected Trends in the Stability and Dissociation Kinetics of Lanthanide(III) Complexes with Cyclen-Based Ligands across the Lanthanide Series. Inorg. Chem. 2020, 59 (12), 8184– 8195, DOI: 10.1021/acs.inorgchem.0c0052048https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXot1eitbY%253D&md5=76f902afc753ddb3a6ada1d5c8385553Unexpected Trends in the Stability and Dissociation Kinetics of Lanthanide(III) Complexes with Cycle-Based Ligands across the Lanthanide SeriesGarda, Zoltan; Nagy, Viktoria; Rodriguez-Rodriguez, Aurora; Pujales-Paradela, Rosa; Patinec, Veronique; Angelovski, Goran; Toth, Eva; Kalman, Ferenc K.; Esteban-Gomez, David; Tripier, Raphael; Platas-Iglesias, Carlos; Tircso, GyulaInorganic Chemistry (2020), 59 (12), 8184-8195CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)We report a detailed study of the thermodn. stability and dissocn. kinetics of lanthanide complexes with two ligands contg. a cyclen unit, a Me group, a picolinate arm, and two acetate pendant arms linked to two nitrogen atoms of the macrocycle in either cis (1,4-H3DO2APA) or trans (1,7-H3DO2APA) positions. The stability consts. of the Gd3+ complexes with these two ligands are very similar, with log KGdL values of 16.98 and 16.33 for the complexes of 1,4-H3DO2APA and 1,7-H3DO2APA, resp. The stability consts. of complexes with 1,4-H3DO2APA follow the usual trend, increasing from log KLaL = 15.96 to log KLuL = 19.21. However, the stability of [Ln(1,7-DO2APA)] complexes decreases from log K = 16.33 for Gd3+ to 14.24 for Lu3+. The acid-catalyzed dissocn. rates of the Gd3+ complexes differ by a factor of ∼ 15, with rate consts. (k1) of 1.42 and 23.5 M-1 s-1 for [Gd(1,4-DO2APA)] and [Gd(1,7-DO2APA)], resp. This difference is magnified across the lanthanide series to reach a 5 orders of magnitude higher k1 for [Yb(1,7-DO2APA)] (1475 M-1 s-1) than for [Yb(1,4-DO2APA)] (5.79 x 10-3 M-1 s-1). The acid-catalyzed mechanism involves the protonation of a carboxylate group, followed by a cascade of proton-transfer events that result in the protonation of a nitrogen atom of the cyclen unit. D. functional theory calcns. suggest a correlation between the strength of the Ln-Ocarboxylate bonds and the kinetic inertness of the complex, with stronger bonds providing more inert complexes. The 1H NMR resonance of the coordinated water mol. in the [Yb(1,7-DO2APA)] complex at 176 ppm provides a sizable chem. exchange satn. transfer effect thanks to a slow water exchange rate of (15.9 ± 1.6) x 103 s-1. The arrangement of the ligand donor atoms around the lanthanide ion provokes dramatic differences in the thermodn. stabilities and dissocn. kinetics of lanthanide complexes, as demonstrated by investigating the complexes with two isomeric cyclen-based ligands, contg. a picolinate arm and two acetate arms in either positions 1,7 or 1,4 of the macrocyclic structure.
- 49Jannin, S.; Helm, L.; Bodenhausen, G. Kinetics of Yttrium–Ligand Complexation Monitored Using Hyperpolarized 89 Y as a Model for Gadolinium in Contrast Agents. J. Am. Chem. Soc. 2010, 132 (14), 5006– 5007, DOI: 10.1021/ja101395449https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXjs1Wrsr4%253D&md5=0aa927480b82bc175a938ab9ca7eaabaKinetics of Yttrium-Ligand Complexation Monitored Using Hyperpolarized 89Y as a Model for Gadolinium in Contrast AgentsMieville, Pascal; Jannin, Sami; Helm, Lothar; Bodenhausen, GeoffreyJournal of the American Chemical Society (2010), 132 (14), 5006-5007CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Hyperpolarization by dissoln. dynamic nuclear polarization (DNP) enhances 89Y spin magnetization by 3 to 4 orders of magnitude and provides a way to monitor yttrium-ligand complexation "on the fly" by means of 89Y NMR. In this communication, we show an example of free yttrium Y3+ being complexed with 1,4,7,10-tetrakis(acetamido)-1,4,7,10-tetraazacyclododecane (DOTAM) to form [Y(DOTAM)(H2O)]3+ as a model for gadolinium in contrast agents.
- 50Tickner, B. J.; Stasiuk, G. J.; Duckett, S. B.; Angelovski, G. The Use of Yttrium in Medical Imaging and Therapy: Historical Background and Future Perspectives. Chem. Soc. Rev. 2020, 49 (17), 6169– 6185, DOI: 10.1039/C9CS00840C50https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB38jmtVynuw%253D%253D&md5=6abc5c18a5813e7bb6df74d2c8cd8714The use of yttrium in medical imaging and therapy: historical background and future perspectivesTickner Ben J; Stasiuk Graeme J; Duckett Simon B; Angelovski GoranChemical Society reviews (2020), 49 (17), 6169-6185 ISSN:.Yttrium is a chemically versatile rare earth element that finds use in a range of applications including lasers and superconductors. In medicine, yttrium-based materials are used in medical lasers and biomedical implants. This is extended through the array of available yttrium isotopes to enable roles for (90)Y complexes as radiopharmaceuticals and (86)Y tracers for positron emission tomography (PET) imaging. The naturally abundant isotope (89)Y is proving to be suitable for nuclear magnetic resonance investigations, where initial reports in the emerging field of hyperpolarised magnetic resonance imaging (MRI) are promising. In this review we explore the coordination and radiochemical properties of yttrium, and its role in drugs for radiotherapy, PET imaging agents and perspectives for applications in hyperpolarised MRI.
- 51Vaughn, B. A.; Koller, A. J.; Chen, Z.; Ahn, S. H.; Loveless, C. S.; Cingoranelli, S. J.; Yang, Y.; Cirri, A.; Johnson, C. J.; Lapi, S. E.; Chapman, K. W.; Boros, E. Homologous Structural, Chemical, and Biological Behavior of Sc and Lu Complexes of the Picaga Bifunctional Chelator: Toward Development of Matched Theranostic Pairs for Radiopharmaceutical Applications. Bioconjugate Chem. 2021, 32 (7), 1232– 1241, DOI: 10.1021/acs.bioconjchem.0c0057451https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisVyiu7rN&md5=5bca186810cf291bf588946144fc4ca2Homologous Structural, Chemical, and Biological Behavior of Sc and Lu Complexes of the Picaga Bifunctional Chelator: Toward Development of Matched Theranostic Pairs for Radiopharmaceutical ApplicationsVaughn, Brett A.; Koller, Angus J.; Chen, Zhihengyu; Ahn, Shin Hye; Loveless, C. Shaun; Cingoranelli, Shelbie J.; Yang, Yi; Cirri, Anthony; Johnson, Christopher J.; Lapi, Suzanne E.; Chapman, Karena W.; Boros, EszterBioconjugate Chemistry (2021), 32 (7), 1232-1241CODEN: BCCHES; ISSN:1043-1802. (American Chemical Society)The radioactive isotopes scandium-44/47 and lutetium-177 are gaining relevance for radioimaging and radiotherapy, resulting in a surge of studies on their coordination chem. and subsequent applications. Although the trivalent ions of these elements are considered close homologues, dissimilar chem. behavior is obsd. when they are complexed by large ligand architectures due to discrepancies between Lu(III) and Sc(III) ions with respect to size, chem. hardness, and Lewis acidity. Here, authors demonstrate that Lu and Sc complexes of 1,4-bis(methoxycarbonyl)-7-[(6-carboxypyridin-2-yl)methyl]-1,4,7-triazacyclononane (H3mpatcn) and its corresponding bioconjugate picaga-DUPA can be employed to promote analogous structural features and, subsequently, biol. properties for coordination complexes of these ions. The close homol. was evidenced using potentiometric methods, computational modeling, variable temp. mass spectrometry, and pair distribution function anal. of x-ray scattering data. Radiochem. labeling, in vitro stability, and biodistribution studies with Sc-47 and Lu-177 indicate that the 7-coordinate ligand environment of the bifunctional picaga ligand is compatible with biol. applications and the future investigation of β-emitting, picaga-chelated Sc and Lu isotopes for radiotherapy.
- 52Caravan, P.; Ellison, J. J.; McMurry, T. J.; Lauffer, R. B. Gadolinium(III) Chelates as MRI Contrast Agents: Structure, Dynamics, and Applications. Chem. Rev. 1999, 99 (9), 2293– 2352, DOI: 10.1021/cr980440x52https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXlt12rsrg%253D&md5=10b76764c56cadb0b2426c6bdf01506bGadolinium(III) Chelates as MRI Contrast Agents: Structure, Dynamics, and ApplicationsCaravan, Peter; Ellison, Jeffrey J.; McMurry, Thomas J.; Lauffer, Randall B.Chemical Reviews (Washington, D. C.) (1999), 99 (9), 2293-2352CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review with 343 refs. on gadolinium(III) chelates judged to be of sufficient stability for in vivo use. Topics covered include soln. and solid state structures, relaxation theory, phys. properties, and macromol. conjugates.
- 53Le Fur, M.; Molnár, E.; Beyler, M.; Kálmán, F. K.; Fougère, O.; Esteban-Gómez, D.; Rousseaux, O.; Tripier, R.; Tircsó, G.; Platas-Iglesias, C. A Coordination Chemistry Approach to Fine-Tune the Physicochemical Parameters of Lanthanide Complexes Relevant to Medical Applications. Chem. – Eur. J. 2018, 24 (13), 3127– 3131, DOI: 10.1002/chem.20170552853https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXisFaqtLc%253D&md5=0a02217fa42e5b28904502fb6e6ed569A Coordination Chemistry Approach to Fine-Tune the Physicochemical Parameters of Lanthanide Complexes Relevant to Medical ApplicationsLe Fur, Mariane; Molnar, Eniko; Beyler, Maryline; Kalman, Ferenc K.; Fougere, Olivier; Esteban-Gomez, David; Rousseaux, Olivier; Tripier, Raphael; Tircso, Gyula; Platas-Iglesias, CarlosChemistry - A European Journal (2018), 24 (13), 3127-3131CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)The geometric features of two pyclen-based ligands possessing identical donor atoms but different site organization have a profound impact in their complexation properties toward lanthanide ions. The ligand contg. two acetate groups and a picolinate arm arranged in a sym. fashion (L1) forms a Gd3+ complex being two orders of magnitude less stable than its dissym. analog GdL2. Besides, GdL1 experiences a much faster dissocn. following the acid-catalyzed mechanism than GdL2. On the contrary, GdL1 exhibits a lower exchange rate of the coordinated water mol. compared to GdL2. These very different properties are related to different strengths of the Gd-ligand bonds assocd. to steric effects, which hinder the coordination of a water mol. in GdL2 and the binding of acetate groups in GdL1.
- 54Roca-Sabio, A.; Regueiro-Figueroa, M.; Esteban-Gómez, D.; de Blas, A.; Rodríguez-Blas, T.; Platas-Iglesias, C. Density Functional Dependence of Molecular Geometries in Lanthanide(III) Complexes Relevant to Bioanalytical and Biomedical Applications. Comput. Theor. Chem. 2012, 999, 93– 104, DOI: 10.1016/j.comptc.2012.08.02054https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xhs1Gqs7jI&md5=3c5726b0bae1d7742f55d8ab06120b53Density functional dependence of molecular geometries in lanthanide(III) complexes relevant to bioanalytical and biomedical applicationsRoca-Sabio, Adrian; Regueiro-Figueroa, Martin; Esteban-Gomez, David; de Blas, Andres; Rodriguez-Blas, Teresa; Platas-Iglesias, CarlosComputational & Theoretical Chemistry (2012), 999 (), 93-104CODEN: CTCOA5; ISSN:2210-271X. (Elsevier B.V.)A set of 15 lanthanide-contg. model systems was used to evaluate the performance of 15 commonly available d. functionals (SVWN, SPL, BLYP, G96LYP, mPWLYP, B3LYP, BH&HLYP, B3PW91, BB95, mPWB95, TPSS, TPSSh, M06, CAM-B3LYP and wB97XD) in geometry detn., benchmarked against MP2 calcns. The best agreement between DFT optimized geometries and those obtained from MP2 calcns. is provided by meta-GGA and hybrid meta-GGA functionals. The use of hybrid-GGA functionals such as BH&HLYP and B3PW91 also provide reasonably good results, while B3LYP provides an important overestimation of the metal-ligand bonds. The performance of different basis sets to describe the ligand(s) atoms, as well as the use of large-core (LC) RECPs and small-core (SC) RECPs, has been also assessed. Our calcns. show that SCRECP calcns. provide somewhat shorter GdIII-donor distances than the LCRECP approach, the av. contraction of bond distances for the systems investigated amounting to 0.033 Å. However, geometry optimizations with the SCRECP (in combination with the mPWB95 functional and the 6-31G(d) basis set for the ligand atoms) take about 15 times longer than the LC counterparts, and about four times longer than MP2/LCRECP/6-31G(d) calcns. The 6-31G(d), 6-311G(d), 6-311G(d,p) or cc-pVDZ basis sets, in combination with LCRECPs, appear to offer an adequate balance between accuracy and computational cost for the description of mol. geometries of LnIII complexes. Electronic energies calcd. with the the cc-pVxZ family (x = D-6) indicate a relative fast convergence to the complete basis set (CBS) limit with basis set size. The inclusion of bulk solvent effects (IEFPCM) was shown to provoke an important impact on the calcd. geometries, particularly on the metal-nitrogen distances. Calcns. performed on lanthanide complexes relevant for practical applications confirmed the important effect of the solvent on the calcd. geometries.
- 55Inoue, M. B.; Inoue, M.; Muñoz, I. C.; Bruck, M. A.; Fernando, Q. Syntheses of New 15-Membered and 16-Membered Macrocyclic Ligands with Three Pendant Acetato Groups and the Structures of the Gadolinium(III) Complexes. Inorg. Chim. Acta 1993, 209, 29– 34, DOI: 10.1016/S0020-1693(00)84976-255https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXms1Wmsrk%253D&md5=db33a0211f1baedc2ec3a50405445496Syntheses of new 15-membered and 16-membered macrocyclic ligands with three pendant acetato groups and the structures of the gadolinium(III) complexesInoue, Michiko B.; Inoue, Motomichi; Munoz, Iliana C.; Bruck, Michael A.; Fernando, QuintusInorganica Chimica Acta (1993), 209 (1), 29-34CODEN: ICHAA3; ISSN:0020-1693.A condensation of diethylenetriaminepentaacetic dianhydride with ethylenediamine gave a 15-membered macrocyclic ligand with 3 pendant acetato groups, (15-dtpa-en)H3 = C10H18N5O2(CH2CO2H)3; a 16-membered analog, (16-dtpa-pn)H3 = C11H20N5O2(CH2CO2H)3, was obtained using 1,3-propanediamine instead of ethylenediamine. The structures of their Gd(III) complexes, Gd2(15-dtpa-en)2.16H2O and Gd(16-dtpa-pn).4H2O, were detd. by x-ray analyses. Gd2(15-dtpa-en)2.16H2O crystd. as orthorhombic, space group Pbca, a 18.205(1), b 18.930(1), c 15.609(1) Å, Z = 4, R = 0.026, Rw = 0.042. Two Gd(III) ions are located between 2 ligand mols., forming a binuclear metal chelate mol. with a center of inversion. The coordination geometry around a metal ion is described as a distorted tricapped trigonal prism that consists of 9 coordinated atoms. Gd(16-dtpa-pn).4H2O crystd. as monoclinic, space group P21/c, a 8.246(2), b 14.995(3), c 19.367(4) Å, β 90.258(2)°, Z = 4, R = 0.021, Rw = 0.035. In this compd., a H2O mol. and a single ligand mol. are coordinated to a Gd(III), forming a mononuclear chelate with a tricapped trigonal prism. The structural differences between the 2 Gd(III) complexes are a result of the differences in the favorable conformations assumed by the 2 macrocyclic ligands.
- 56Bader, R. F. W.; Carroll, M. T.; Cheeseman, J. R.; Chang, C. Properties of Atoms in Molecules: Atomic Volumes. J. Am. Chem. Soc. 1987, 109 (26), 7968– 7979, DOI: 10.1021/ja00260a00656https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2sXmtlGlurc%253D&md5=0676f2a588f1104c3d65aa3a13d63b01Properties of atoms in molecules: atomic volumesBader, Richard F. W.; Carroll, Marshall T.; Cheeseman, James R.; Chang, ChengJournal of the American Chemical Society (1987), 109 (26), 7968-79CODEN: JACSAT; ISSN:0002-7863.The theory of atoms in mols. defines an atom and the av. values of its properties. The intersection of an at. surface, as defined by a property of the charge d., with a particular envelope of the charge d. defines the vol. of an atom in a mol. The value of the d. envelope used to bound the open portion of an at. region can be chosen on the basis of comparison with measured properties. The nature of the results are, in any event, independent of the choice for envelopes which contain >96% of the total electronic charge and lie within the usual range of van der Waals contact distances. It is shown that the vols. of Me and methylene groups in normal hydrocarbons are transferable properties, as are their charge distributions, populations, and energies. The vol. of a C atom subject to steric crowding decreases as its stability and electron population increase. This behavior is opposite to that found for a C atom in a system with geometric strain as found in cyclic and bicyclic mols. The stability, population, and vol. of a C atom all undergo parallel increases as the atom is subjected to an increasing degree of geometric strain. The vols. of the bridgehead C atoms in bicyclo[1.1.0]butane and [1.1.1]propellane are 1.2 and 1.5 times, resp., the vol. of a Me C atom. As anticipated on the basis of the orbital model, an increase in geometric strain is correlated with an increase in s character and thus finds the electron population, stability, and vol. of a C atom to undergo the same parallel increases in value through the series ethane, ethylene, acetylene. As a first step in the investigation of how atoms fit together, the changes in the at. vols. accompanying the formation of a H bond are detd.
- 57Neese, F. The ORCA Program System. WIREs Comput. Mol. Sci. 2012, 2 (1), 73– 78, DOI: 10.1002/wcms.8157https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhvFGls7s%253D&md5=a753e33a6f9a326553295596f5c754e5The ORCA program systemNeese, FrankWiley Interdisciplinary Reviews: Computational Molecular Science (2012), 2 (1), 73-78CODEN: WIRCAH; ISSN:1759-0884. (Wiley-Blackwell)A review. ORCA is a general-purpose quantum chem. program package that features virtually all modern electronic structure methods (d. functional theory, many-body perturbation and coupled cluster theories, and multireference and semiempirical methods). It is designed with the aim of generality, extendibility, efficiency, and user friendliness. Its main field of application is larger mols., transition metal complexes, and their spectroscopic properties. ORCA uses std. Gaussian basis functions and is fully parallelized. The article provides an overview of its current possibilities and documents its efficiency.
- 58Neese, F. Software Update: The ORCA Program System, Version 4.0. WIREs Comput. Mol. Sci. 2018, 8 (1), e1327 DOI: 10.1002/wcms.1327There is no corresponding record for this reference.
- 59Reiher, M. Douglas–Kroll–Hess Theory: A Relativistic Electrons-Only Theory for Chemistry. Theor. Chem. Acc. 2006, 116 (1–3), 241– 252, DOI: 10.1007/s00214-005-0003-259https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28Xns1Sqs7Y%253D&md5=32bd8fff4b0c49e80dcd3c97af2f34f4Douglas-Kroll-Hess Theory: A relativistic electrons-only theory for chemistryReiher, MarkusTheoretical Chemistry Accounts (2006), 116 (1-3), 241-252CODEN: TCACFW; ISSN:1432-881X. (Springer GmbH)A review. A unitary transformation allows to sep. (block-diagonalize) the Dirac Hamiltonian into two parts one part: solely describes electrons, while the other gives rise to neg.-energy states, which are the so-called positronic states. The block-diagonal form of the Hamiltonian no longer accounts for the coupling of both kinds of states. The pos.-energy ('electrons-only') part can serve as a 'fully' relativistic electrons-only theory, which can be understood as a rigorous basis for chem. Recent developments of the Douglas-Kroll-Hess (DKH) method allowed to derive a sequence of expressions, which approx. this electrons-only Hamiltonian up to arbitrary-order. While all previous work focused on the numerical stability and accuracy of these arbitrary-order DKH Hamiltonians, conceptual issues and paradoxa of the method were mostly left aside. In this work, the conceptual side of DKH theory is revisited in order to identify essential aspects of the theory to be distinguished from purely computational consideration.
- 60Chai, J.-D.; Head-Gordon, M. Long-Range Corrected Hybrid Density Functionals with Damped Atom–Atom Dispersion Corrections. Phys. Chem. Chem. Phys. 2008, 10 (44), 6615– 6620, DOI: 10.1039/b810189b60https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtlCksbfO&md5=c7848f8bf050e11972d438aaebd68fdfLong-range corrected hybrid density functionals with damped atom-atom dispersion correctionsChai, Jeng-Da; Head-Gordon, MartinPhysical Chemistry Chemical Physics (2008), 10 (44), 6615-6620CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)We report re-optimization of a recently proposed long-range cor. (LC) hybrid d. functional [J.-D. Chai and M. Head-Gordon, J. Chem. Phys., 2008, 128, 084106] to include empirical atom-atom dispersion corrections. The resulting functional, ωB97X-D yields satisfactory accuracy for thermochem., kinetics, and non-covalent interactions. Tests show that for non-covalent systems, ωB97X-D shows slight improvement over other empirical dispersion-cor. d. functionals, while for covalent systems and kinetics it performs noticeably better. Relative to our previous functionals, such as ωB97X, the new functional is significantly superior for non-bonded interactions, and very similar in performance for bonded interactions.
- 61Chai, J.-D.; Head-Gordon, M. Systematic Optimization of Long-Range Corrected Hybrid Density Functionals. J. Chem. Phys. 2008, 128 (8), 084106 DOI: 10.1063/1.283491861https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXjtVGqtLk%253D&md5=9f138e05dabfb160b1aabaa185585207Systematic optimization of long-range corrected hybrid density functionalsChai, Jeng-Da; Head-Gordon, MartinJournal of Chemical Physics (2008), 128 (8), 084106/1-084106/15CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)A general scheme for systematically modeling long-range cor. (LC) hybrid d. functionals is proposed. Our resulting two LC hybrid functionals are shown to be accurate in thermochem., kinetics, and noncovalent interactions, when compared with common hybrid d. functionals. The qual. failures of the commonly used hybrid d. functionals in some "difficult problems," such as dissocn. of sym. radical cations and long-range charge-transfer excitations, are significantly reduced by the present LC hybrid d. functionals. (c) 2008 American Institute of Physics.
- 62Najibi, A.; Goerigk, L. The Nonlocal Kernel in van Der Waals Density Functionals as an Additive Correction: An Extensive Analysis with Special Emphasis on the B97M-V and ωB97M-V Approaches. J. Chem. Theory Comput. 2018, 14 (11), 5725– 5738, DOI: 10.1021/acs.jctc.8b0084262https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhvV2jsLzE&md5=6a1ebaf23b27f7222f3bda4516d82324The Nonlocal Kernel in van der Waals Density Functionals as an Additive Correction: An Extensive Analysis with Special Emphasis on the B97M-V and ωB97M-V ApproachesNajibi, Asim; Goerigk, LarsJournal of Chemical Theory and Computation (2018), 14 (11), 5725-5738CODEN: JCTCCE; ISSN:1549-9618. (American Chemical Society)The development of van der Waals d. functional approxns. (vdW-DFAs) has gained considerable interest over the past decade. While in a strictest sense, energy calcns. with vdW-DFAs should be carried out fully self-consistently, we demonstrate conclusively for a total of 11 methods that such a strategy only increases the computational time effort without having any significant effect on energetic properties, electron densities, or orbital-energy differences. The strategy to apply a nonlocal vdW-DFA kernel as an additive correction to a fully converged conventional DFA result is therefore justified and more efficient. As part of our study, we utilize the extensive GMTKN55 database for general main-group thermochem., kinetics, and noncovalent interactions [Phys. Chem. Chem. Phys.2017, 19, 32184], which allows us to analyze the very promising B97M-V [J. Chem. Phys. 2015, 142, 074111] and ωB97M-V [J. Chem. Phys. 2016, 144, 214110] DFAs. We also present new DFT-D3(BJ) based counterparts of these two methods and of ωB97X-V [J. Chem. Theory Comput 2013, 9, 263], which are faster variants with similar accuracy. Our study concludes with updated recommendations for the general method user, based on our current overview of 325 dispersion-cor. and -uncorrected DFA variants analyzed for GMTKN55. VdW-DFAs are the best representatives of the three highest rungs of Jacob's Ladder, namely, B97M-V, ωB97M-V, and DSD-PBEP86-NL.
- 63Weigend, F.; Ahlrichs, R. Balanced Basis Sets of Split Valence, Triple Zeta Valence and Quadruple Zeta Valence Quality for H to Rn: Design and Assessment of Accuracy. Phys. Chem. Chem. Phys. 2005, 7 (18), 3297– 3305, DOI: 10.1039/b508541a63https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXpsFWgu7o%253D&md5=a820fb6055c993b50c405ba0fc62b194Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: Design and assessment of accuracyWeigend, Florian; Ahlrichs, ReinhartPhysical Chemistry Chemical Physics (2005), 7 (18), 3297-3305CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)Gaussian basis sets of quadruple zeta valence quality for Rb-Rn are presented, as well as bases of split valence and triple zeta valence quality for H-Rn. The latter were obtained by (partly) modifying bases developed previously. A large set of more than 300 mols. representing (nearly) all elements-except lanthanides-in their common oxidn. states was used to assess the quality of the bases all across the periodic table. Quantities investigated were atomization energies, dipole moments and structure parameters for Hartree-Fock, d. functional theory and correlated methods, for which we had chosen Moller-Plesset perturbation theory as an example. Finally recommendations are given which type of basis set is used best for a certain level of theory and a desired quality of results.
- 64Pantazis, D. A.; Neese, F. All-Electron Scalar Relativistic Basis Sets for the Lanthanides. J. Chem. Theor. Comput. 2009, 5 (9), 2229– 2238, DOI: 10.1021/ct900090f64https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXpslaiu7o%253D&md5=edc7672c2e7514f1696d1fc2270e9611All-electron scalar relativistic basis sets for the lanthanidesPantazis, Dimitrios A.; Neese, FrankJournal of Chemical Theory and Computation (2009), 5 (9), 2229-2238CODEN: JCTCCE; ISSN:1549-9618. (American Chemical Society)Segmented all-electron relativistically contracted (SARC) basis sets are constructed for the elements 57La-71Lu and optimized for d. functional theory (DFT) applications. The basis sets are intended for use in combination with the DKH2 or ZORA scalar relativistic Hamiltonians for which individually optimized contractions are provided. Significant computational advantages can be realized owing to the loose contraction of the SARC basis sets compared to generally contracted basis sets, while their compact size allows them to replace effective core potentials for routine studies of lanthanide complexes. The new basis sets are evaluated in DFT calcns. of the first four ionization energies of the lanthanides. They yield results that accurately reproduce the exptl. trends, confirming a balanced treatment of different electronic configurations. The performance of the basis sets is further assessed in mol. systems with a comprehensive study of the lanthanide trihalides. Despite their compact size, the SARC basis sets demonstrate consistent, efficient, and reliable performance and will be esp. useful in calcns. of mol. properties that require explicit treatment of the core electrons.
- 65Bader, R. F. W. Atoms in Molecules. Acc. Chem. Res. 1985, 18, 9– 15, DOI: 10.1021/ar00109a00365https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2MXmtFGgsA%253D%253D&md5=602888ebc5fbe1c57b86efd88972306cAtoms in moleculesBader, R. F. W.Accounts of Chemical Research (1985), 18 (1), 9-15CODEN: ACHRE4; ISSN:0001-4842.A review with 21 refs.
- 66Tosi, M. P.; Fumi, F. G. Ionic Sizes And Born Repulsive Parameters In The NaCl-Type Alkali Halides-II: The Generalized Huggins-Mayer Form. J. Phys. Chem. Solids 1964, 25, 45– 52, DOI: 10.1016/0022-3697(64)90160-X66https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF2cXkvFKjtQ%253D%253D&md5=925d52709fa26f0090f5b6e4a5a564f7Ionic sizes and Born repulsive parameters in the NaCl-type alkali halides. II. Generalized Huggins-Mayer formsTosi, M. P.; Fumi, F. G.Journal of Physics and Chemistry of Solids (1964), 25 (1), 45-52CODEN: JPCSAW; ISSN:0022-3697.The procedure described for the detn. of the crystal radii of the ions in the individual NaCl-type alkali halides from solid-state data by the Born model is applied, adopting a generalized Huggins-Mayer form for the Born repulsive energy (i.e. allowing the hardness parameter to vary from salt to salt). The resulting values of the crystal radii agree within 0.05 A. with the values obtained with the Huggins-Mayer and Pauling forms. This indicates that the Born model, irrespective of the specific plausible form adopted for the Born repulsive energy, leads to relative values of the crystal radii for the alkali and halogen ions in the NaCl structure exceeding by ∼0.3 A. the traditional relative values, which refer to nearly free ions. Qual. and quant. evidence supporting these ionic deformations is discussed.
- 67Pauling, L. The Sizes of Ions and the Structure of Ionic Crystals. J. Am. Chem. Soc. 1927, 49 (3), 765– 790, DOI: 10.1021/ja01402a01967https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaB2sXhtFGjsw%253D%253D&md5=7142d81e5f65e04605b198cc0eaf09ccSizes of ions and structure of ionic crystalsPauling, LinusJournal of the American Chemical Society (1927), 49 (), 765-92CODEN: JACSAT; ISSN:0002-7863.With an at. model derived from the wave mechanics of Schr.ovrddot.odinger, size-screening consts. have been calcd. for the electrons in many-electron atoms and ions. After a discussion of the forces between ions, and of the significance of ionic sizes, values of the univalent crystal radius and the crystal radius are derived for a large no. of ions with the aid of these screening consts., using as a starting point the observed inter-atomic distances in crystals of NaF, KCl, RbBr, CsI and Li2O. The theoretical result is derived that ionic compds. MX2 will crystallize with fluorite structure if the radius ratio RM/RX is greater than 0.65, and with the rutile (or anatase) structure if it is less. This result is exptly. substantiated. Theoretically a binary compd. should have the sphalerite or wurzite structure instead of the NaCl structure if the radius ratio is less than 0.33. The oxide, sulfide, selenide and telluride of Be conform to this requirement, and are to be considered as ionic crystals. It is found, however, that such "tetrahedral" crystals are particularly apt to Show deformation, and it is suggested that this is a tendency of the anion to share an electron pair. with each cation.
- 68Lu, T.; Chen, F. Multiwfn: A Multifunctional Wavefunction Analyzer. J. Comput. Chem. 2012, 33 (5), 580– 592, DOI: 10.1002/jcc.2288568https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFykurjN&md5=deb758db27c2d0c4df698db0a3fd066fMultiwfn: A multifunctional wavefunction analyzerLu, Tian; Chen, FeiwuJournal of Computational Chemistry (2012), 33 (5), 580-592CODEN: JCCHDD; ISSN:0192-8651. (John Wiley & Sons, Inc.)Multiwfn is a multifunctional program for wavefunction anal. Its main functions are: (1) Calcg. and visualizing real space function, such as electrostatic potential and electron localization function at point, in a line, in a plane or in a spatial scope. (2) Population anal. (3) Bond order anal. (4) Orbital compn. anal. (5) Plot d.-of-states and spectrum. (6) Topol. anal. for electron d. Some other useful utilities involved in quantum chem. studies are also provided. The built-in graph module enables the results of wavefunction anal. to be plotted directly or exported to high-quality graphic file. The program interface is very user-friendly and suitable for both research and teaching purpose. The code of Multiwfn is substantially optimized and parallelized. Its efficiency is demonstrated to be significantly higher than related programs with the same functions. Five practical examples involving a wide variety of systems and anal. methods are given to illustrate the usefulness of Multiwfn. The program is free of charge and open-source. Its precompiled file and source codes are available from http://multiwfn.codeplex.com. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011.
- 69Wada, A.; Watanabe, M.; Yamanoi, Y.; Nishihara, H. Modification of the Luminescence Spectra of Chloro(Tetrapyridylcyclotetramine)Europium Complexes by Fine Tuning of the Eu–Cl Distance with Outer-Sphere Counterions in the Solid State, in a Polymer Matrix and in Solution. Chem. Commun. 2008, 1671– 1673, DOI: 10.1039/b716987f69https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXjs12ltb8%253D&md5=78052a8f6da214c93a7eb11cc50bc91fModification of the luminescence spectra of chloro(tetrapyridylcyclotetramine)europium complexes by fine tuning of the Eu-Cl distance with outer-sphere counterions in the solid state, in a polymer matrix and in solutionWada, Atsushi; Watanabe, Masayuki; Yamanoi, Yoshinori; Nishihara, HiroshiChemical Communications (Cambridge, United Kingdom) (2008), (14), 1671-1673CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)Controlling the coordination environments and the luminescence of Eu3+ complexes with outer-sphere counterions was achieved in the solid state, in a polymer matrix and in soln.
- 70Natrajan, L. S.; Khoabane, N. M.; Dadds, B. L.; Muryn, C. A.; Pritchard, R. G.; Heath, S. L.; Kenwright, A. M.; Kuprov, I.; Faulkner, S. Probing the Structure, Conformation, and Stereochemical Exchange in a Family of Lanthanide Complexes Derived from Tetrapyridyl-Appended Cyclen. Inorg. Chem. 2010, 49 (17), 7700– 7709, DOI: 10.1021/ic100447m70https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXpsVKltLk%253D&md5=d341e3030cb7e07f601633de58ab40f2Probing the Structure, Conformation, and Stereochemical Exchange in a Family of Lanthanide Complexes Derived from Tetrapyridyl-Appended CyclenNatrajan, Louise S.; Khoabane, Ntai M.; Dadds, Benjamin L.; Muryn, Christopher A.; Pritchard, Robin G.; Heath, Sarah L.; Kenwright, Alan M.; Kuprov, Ilya; Faulkner, StephenInorganic Chemistry (2010), 49 (17), 7700-7709CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)A series of lanthanide complexes have been synthesized from 1,4,7,10-tetrakis(2-pyridylmethyl)-1,4,7,10-tetraazacyclododecane (LPy). Crystallog. studies indicate that, in the solid phase, all of the lanthanide ions are 9-coordinate and are bound to eight N atoms from the donor ligand, with the ninth site being filled by a counterion or solvent mol. In soln., time-resolved luminescence studies indicate that the luminescence exhibits contributions from two species corresponding to the nonhydrated and hydrated forms. The NMR spectra in protic media show two dominant isomers on the NMR time scale; furthermore, the spectra are very different from those obtained for 1,4,7,10-tetraazacyclododecane-N',N'',N''',N''''-tetraacetic acid (DOTA) and its derivs. The different forms of the complex undergo slow conformational and enantiomeric exchange in soln., which has been measured by NMR. The exchange path has been mapped out by d. functional theory calcns. and shows multiple metastable conformations (with respect to the dihedral angles of the cyclen ring). This contrasts with the established NMR behavior of DOTA complexes, which has been described by a two-state soln. equil.
- 71Gunnlaugsson, T.; Davies, R. J. H.; Kruger, P. E.; Jensen, P.; McCabe, T.; Mulready, S.; O’Brien, J. E.; Stevenson, C. S.; Fanning, A.-M. Cyclen Based Lanthanide Ion Ribonuclease Mimics: The Effect of Pyridine Cofactors upon Phosphodiester HPNP Hydrolysis. Tetrahedron Lett. 2005, 46 (21), 3761– 3766, DOI: 10.1016/j.tetlet.2005.03.15071https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXjs1SnsL4%253D&md5=6b73afa76a124f9c3db82f8b39f67130Cyclen based lanthanide ion ribonuclease mimics: the effect of pyridine cofactors upon phosphodiester HPNP hydrolysisGunnlaugsson, Thorfinnur; Davies, R. Jeremy H.; Kruger, Paul E.; Jensen, Paul; McCabe, Thomas; Mulready, Sinead; O'Brien, John E.; Stevenson, Clarke S.; Fanning, Ann-MarieTetrahedron Letters (2005), 46 (21), 3761-3766CODEN: TELEAY; ISSN:0040-4039. (Elsevier B.V.)The cyclen based pyridine complexes 1Ln-3Ln (Ln = La(III) and Eu(III); 1-3 = N-(pyridin-x-yl)-2-[2,7,10-tris[(pyridin-x-ylcarbamoyl)methyl]-1,4,7,10-tetraazacyclododec-1-yl]acetamide (x = 2, 3, 4)) were synthesized as metallo-RNase mimics and their ability to hydrolytically cleave the phosphodiester of HPNP ((p-O2NC6H4O)(HOCHMeCH2O)PO2-) at 37° was studied using UV-visible spectroscopy, whereas the binding of the substrate was evaluated using 31P NMR and Eu(III)-luminescent measurements. In contrast 2Ln gave rise to fast pH dependent hydrolysis of HPNP, with max. efficiency at pH ∼8.2, and with a half-life of ∼1 h, the 1Ln and 3Ln complexes are inactive, emphasizing the importance of the nature of the pyridine isomer as a cofactor in the hydrolytic process. The crystal and mol. structures of the La, Eu and Gd complexes with the pyridin-3-yl-derived macrocycle were detd. by x-ray crystallog.
- 72Gao, J.; Ye, K.; He, M.; Xiong, W.-W.; Cao, W.; Lee, Z. Y.; Wang, Y.; Wu, T.; Huo, F.; Liu, X.; Zhang, Q. Tuning Metal–Carboxylate Coordination in Crystalline Metal–Organic Frameworks through Surfactant Media. J. Solid State Chem. 2013, 206, 27– 31, DOI: 10.1016/j.jssc.2013.07.03172https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsFKjt7nM&md5=92e5c8d8b7724afc9b1bd4e25e3c1df0Tuning metal-carboxylate coordination in crystalline metal-organic frameworks through surfactant mediaGao, Junkuo; Ye, Kaiqi; He, Mi; Xiong, Wei-Wei; Cao, Wenfang; Lee, Zhi Yi; Wang, Yue; Wu, Tom; Huo, Fengwei; Liu, Xiaogang; Zhang, QichunJournal of Solid State Chemistry (2013), 206 (), 27-31CODEN: JSSCBI; ISSN:0022-4596. (Elsevier B.V.)Although it was widely demonstrated that surfactants can efficiently control the size, shape and surface properties of micro/nanocrystals of metal-org. frameworks (MOFs) due to the strong interactions between surfactants and crystal facets of MOFs, the use of surfactants as reaction media to grow MOF single crystals is unprecedented. Compared with ionic liqs., surfactants are much cheaper and can have multifunctional properties such as acidic, basic, neutral, cationic, anionic, or even block. These factors strongly motivate the authors to develop a new synthetic strategy: growing cryst. MOFs in surfactants. Eight new two-dimensional (2D) or three-dimensional (3D) MOFs were successfully synthesized in an industrially-abundant and environmentally-friendly surfactant: polyethylene glycol-200 (PEG-200). Eight different coordination modes of carboxylates, ranging from monodentate η1 mode to tetra-donor coordination μ3-η1:η2:η1 mode, were founded in the authors' research. The magnetic properties of Co-based MOFs were studied and MOF NTU-Z6b showed a phase transition with a Curie temp. (Tc) at 5 K. The authors' strategy of growing cryst. MOFs in surfactant could offer exciting opportunities for prepg. novel MOFs with diverse structures and interesting properties.
- 73Gao, S.; George, S. J.; Zhou, Z.-H. Interaction of Gd-DTPA with Phosphate and Phosphite: Toward the Reaction Intermediate in Nephrogenic Systemic Fibrosis. Dalton Trans. 2016, 45 (12), 5388– 5394, DOI: 10.1039/C5DT04172D73https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XpsVWmtg%253D%253D&md5=f8a05ae3e4fddd24ba3a49fcf62dd89cInteraction of Gd-DTPA with phosphate and phosphite: toward the reaction intermediate in nephrogenic systemic fibrosisGao, Song; George, Simon J.; Zhou, Zhao-HuiDalton Transactions (2016), 45 (12), 5388-5394CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)Direct reactions of the MRI contrast agent K2[Gd(DTPA)(H2O)]·5H2O (1) (H5DTPA = diethylenetriaminepentaacetic acid) with dipotassium hydrogen phosphate (K2HPO4) or phosphite (K2HPO3) result in the isolation of well-defined Gd-DTPA phosphite K6[Gd2(DTPA)2(HPO3)]·7H2O (2) or phosphate K6[Gd2(DTPA)2(HPO4)]·10H2O (3), resp. Their lanthanum analogs K4[La2(DTPA)2(H2O)]·8H2O (4), K6[La2(DTPA)2(HPO3)]·7H2O (5) and K6[La2(DTPA)2(HPO4)]·10H2O (6) are used for comparison. The phosphate and phosphite groups are able to substitute the coordinated water mols. in 1 and 4 in a close physiol. aq. soln., and act as bridging ligands to link adjacent Ln(DTPA)2- (Ln = Gd and La) into dimeric structures. Solid state and soln. 13C NMR spectra of dimer 4 show complete dissocn. into its monomeric species in soln., while no dissocn. is obsd. for lanthanum phosphite 5 and phosphate 6 in soln., which show only one set of 13C spectra with the largest downfield shifts at 182.0 and 182.3 ppm resp. Comparisons of the bond distances and spectral data indicate that the interaction between DTPA and central Ln3+ cations are weakened after the substitutions, which support phosphate substituted Gd-DTPA as an initial intermediate in nephrogenic systemic fibrosis.
- 74Onate, C. A.; Okon, I. B.; Vincent, U. E.; Eyube, E. S.; Onyeaju, M. C.; Omugbe, E.; Egharevba, G. O. Non-Relativistic Molecular Modified Shifted Morse Potential System. Sci. Rep. 2022, 12 (1), 15188, DOI: 10.1038/s41598-022-19179-474https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XitlKmsLfM&md5=6a62687a7a36cc124df3330ad4fb618cNon-relativistic molecular modified shifted Morse potential systemOnate, C. A.; Okon, I. B.; Vincent, U. E.; Eyube, E. S.; Onyeaju, M. C.; Omugbe, E.; Egharevba, G. O.Scientific Reports (2022), 12 (1), 15188CODEN: SRCEC3; ISSN:2045-2322. (Nature Portfolio)Abstr.: A shifted Morse potential model is modified to fit the study of the vibrational energies of some mols. Using a traditional technique/methodol., the vibrational energy and the un-normalized radial wave functions were calcd. for the modified shifted Morse potential model. The condition that fits the modified potential for mol. description were deduced together with the expression for the screening parameter. The vibrational energies of SiC, NbO, CP, PH, SiF, NH and Cs2 mols. were computed by inserting their resp. spectroscopic consts. into the calcd. energy equation. It was shown that the calcd. results for all the mols. agreement perfectly with the exptl. RKR values. The present potential performs better than Improved Morse and Morse potentials for cesium dimer. Finally, the real Morse potential model was obtained as a special case of the modified shifted potential.
- 75Janicki, R.; Mondry, A. Structural and Thermodynamic Aspects of Hydration of Gd(iii) Systems. Dalton Trans. 2019, 48, 3380– 3391, DOI: 10.1039/C8DT04869J75https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXjtlWgurw%253D&md5=d7e7dce566397d2e17dea7f1cf2a77a8Structural and thermodynamic aspects of hydration of Gd(III) systemsJanicki, Rafal; Mondry, AnnaDalton Transactions (2019), 48 (10), 3380-3391CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)X-ray crystal structures of Gd(III) and Lu(III) aqua ions as well as their complexes with polyaminopolycarboxylates (EDTA, CDTA, EGTA, DTPA, DOTA) were detd.: [Gd(H2O)9](CF3SO3)3, [Gd(H2O)8]Cl3·C10H20O5, [Lu(H2O)8]Cl3·C12H24O6·4H2O, [C(NH2)3][Gd(EDTA)(H2O)3], [C(NH2)3]2[Lu(EDTA)(H2O)2]ClO4·6H2O, [C(NH2)3][Lu(CDTA)(H2O)2]·6H2O, [C(NH2)3][Gd(EGTA)(H2O)]·2H2O, [C(NH2)2(N2H4)][Gd(HDTPA)(H2O)]·2H2O, Na[Gd(DOTA)(H2O)]·4H2O, and K2[Lu(DOTA)]Cl·4.6H2O. The weighted sums of UV absorption spectra of appropriate crystals were used to reproduce the spectra of the Gd(III) aq. solns. in the temp. range 276-363 K. In aq. soln. the Gd(III)-EGTA, Gd(III)-DTPA and Gd(III)-DOTA complexes exist as almost pure monohydrate [GdL(H2O)]n- species, while in the case of the Gd(III) aqua ion, Gd(III)-EDTA and Gd(III)-CDTA systems the equil. between variously hydrated species were found. The derived molar fractions of these species were used to det. the ΔG, ΔH and ΔS of hydration. These thermodn. functions may be derived not only from the spectra of the hypersensitive transitions, but from other f-f transitions as well. Next the ΔG, ΔH and ΔS values of hydration for the other Ln(III)-EDTA systems (Ln = Pr, Nd, Sm, Eu) were detd. The ΔG298 values of the dehydration reaction for Ln(III)-EDTA complexes (Ln = Pr, Nd, Sm, Eu, Gd, Ho, Er) were almost linearly dependent on the no. of 4f electrons in the whole series of lanthanides. Also, the point, where the ratio of [LnL(H2O)n] : [LnL(H2O)n-1] is 1, shifts along the lanthanide series depending on the ligand denticity - the higher the ligand denticity, the farther the point of the equimolar ratio in the lanthanide series. The presented results are the 1st systematic exptl. study on the thermodn. description of the hydration equil. of Gd(III) compds.
- 76Graeppi, N.; Hugh Powell, D.; Laurenczy, G.; Zékány, L.; Merbach, A. E. Coordination Equilibria and Water Exchange Kinetics of Lanthanide(III) Propylenediaminetetraacetates and Other Magnetic Resonance Imaging Related Complexes. Inorg. Chim. Acta 1995, 235 (1–2), 311– 326, DOI: 10.1016/0020-1693(95)90073-F76https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2MXnsFWmsLc%253D&md5=7f9401e5f1d21179c214e998c4d2480eCoordination equilibria and water exchange kinetics of lanthanide(III) propylenediaminetetraacetates and other magnetic resonance imaging related complexesGraeppi, Nicole; Powell, D. Hugh; Laurenczy, Gabor; Zekany, Laszlo; Merbach, Andre E.Inorganica Chimica Acta (1995), 235 (1-2), 311-26CODEN: ICHAA3; ISSN:0020-1693. (Elsevier)The UV-Vis absorption spectra of aq. solns. of Eu3+ complexes with the hexadentate polyaminocarboxylate ligands EDTA4-, CDTA4-, HDTA3- and PDTA4- were measured as a function of temp. and pressure in the frequency region corresponding to the 7F0→5D0 transition of Eu3+. The results can be explained in terms of equil. between nine-coordinate and eight-coordinate species where the eight-coordinate species contain one less inner sphere water mol. than the nine-coordinate species. The thermodn. parameters, including the reaction vol., for these equil. were detd. 17O NMR transverse relaxation rates and chem. shifts were measured for aq. solns. of the eight-coordinate complexes [Ln(PDTA)(H2O)2]- (Ln = Tb, Dy, Er, Tm, Yb) and [Er(EDTA)(H2O)2]- as a function of temp., pressure and magnetic field. The results were analyzed in terms of the water exchange kinetics on the complexes. The water exchange rate on [Ln(PDTA)(H2O)2]- decreases dramatically with decreasing ionic radius across the lanthanide series from kex298 = (2.4±0.1)×107 s-1 for Ln = Tb to kex298 = (2.8±0.3)×105 s-1 for Ln = Yb. The activation vols. show that this is accompanied by a change of exchange mechanism from associatively activated for Ln = Tb (ΔV # = -7.6±0.3 cm3 mol-1) to dissociatively activated for Ln = Yb (ΔV # = +7.4±0.8 cm3 mol-1). Water exchange on [Er(EDTA)(H2O)2]- (kex298 = (9.8±1.9)×106 s-1) is more than an order of magnitude faster than on [Er(PDTA)(H2O)2]- (kex298 = (5.6±0.5)×105 s-1). These kinetic results can be interpreted in terms of the equil. measured by UV-Vis spectrophotometry. The implications of these observations for the design of new MRI contrast agents are discussed.
- 77Balogh, E.; Mato-Iglesias, M.; Platas-Iglesias, C.; Tóth, É.; Djanashvili, K.; Peters, J. A.; de Blas, A.; Rodríguez-Blas, T. Pyridine- and Phosphonate-Containing Ligands for Stable Ln Complexation. Extremely Fast Water Exchange on the GdIII Chelates. Inorg. Chem. 2006, 45 (21), 8719– 8728, DOI: 10.1021/ic060415777https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XptlWisLc%253D&md5=ec4d1fdf2126910d554d12897de69e8dPyridine- and Phosphonate-Containing Ligands for Stable Ln Complexation. Extremely Fast Water Exchange on the GdIII ChelatesBalogh, Edina; Mato-Iglesias, Marta; Platas-Iglesias, Carlos; Toth, Eva; Djanashvili, Kristina; Peters, Joop A.; de Blas, Andres; Rodriguez-Blas, TeresaInorganic Chemistry (2006), 45 (21), 8719-8728CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)Two novel ligands contg. pyridine units and phosphonate pendant arms, with ethane-1,2-diamine (L2) or cyclohexane-1,2-diamine (L3) backbones, have been synthesized for Ln complexation. The hydration nos. obtained from luminescence lifetime measurements in aq. solns. of the EuIII and TbIII complexes are q = 0.6 (EuL2), 0.7 (TbL2), 0.8 (EuL3), and 0.4 (TbL3). To further assess the hydration equil., we have performed a variable-temp. and -pressure UV-vis spectrophotometric study on the EuIII complexes. The reaction enthalpy, entropy, and vol. for the hydration equil. EuL ↔ EuL(H2O) were calcd. to be ΔH° = -(11.6 ± 2) kJ mol-1, ΔS° = -(34.2 ± 5) J mol-1 K-1, and KEu298 = 1.8 ± 0.3 for EuL2 and ΔH° = -(13.5 ± 1) kJ mol-1, ΔS° = -(41 ± 4) J mol-1 K-1, and KEu298 = 1.7 ± 0.3 for EuL3, resp. Variable-temp. 17O NMR and nuclear magnetic relaxation dispersion (NMRD) were measured for GdL2(H2O)q and GdL3(H2O)q systems. Given the presence of phosphonate groups in the ligand backbone, a second-sphere relaxation mechanism has been included for the anal. of the longitudinal 17O and 1H NMR relaxation rates. The water exchange rate on GdL2(H2O)q, kex298 = (7.0 ± 0.8) × 108 s-1, is extremely high and comparable to that on the GdIII aqua ion, while it is slightly reduced for GdL3(H2O)q, kex298 = (1.5 ± 0.1) × 108 s-1. This fast exchange can be rationalized in terms of a very flexible inner coordination sphere, which is slightly rigidified for L3 by the introduction of the cyclohexyl group on the amine backbone. The water exchange proceeds via a dissociative interchange mechanism, evidenced by the pos. activation vols. obtained from variable-pressure 17O NMR for both GdL2(H2O)q and GdL3(H2O)q (ΔV⧧ = +8.3 ± 1.0 and 8.7 ± 1.0 cm3 mol-1, resp.).
- 78Janicki, R.; Mondry, A. A New Approach to Determination of Hydration Equilibria Constants for the Case of [Er(EDTA)(H2O)n ]− Complexes. Phys. Chem. Chem. Phys. 2014, 16 (48), 26823– 26831, DOI: 10.1039/C4CP04093G78https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvVOmsLfJ&md5=037c1a5513f85b710478f25f8f7ef35cA new approach to determination of hydration equilibria constants for the case of [Er(EDTA)(H2O)n]- complexesJanicki, Rafal; Mondry, AnnaPhysical Chemistry Chemical Physics (2014), 16 (48), 26823-26831CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)Two anionic complexes [Er(EDTA)(H2O)2]- and [Er(EDTA)(H2O)3]- were obtained as the following compds.: [C(NH2)3]2[Er(EDTA)(H2O)2]ClO4·6H2O (1) and Na[Er(EDTA)(H2O)3]·5H2O (2), resp. The UV-visible-NIR absorption spectra of both monocrystals were measured at room temp. and at 4.2 K. The influence of coordination no. on intensities of the f-f transitions and the crystal field splitting of 2S+1LJ multiplets are discussed. The weighted sum of molar absorptivities of f-f transitions in the spectra of 1 and 2 was used to reproduce the absorption bands of the Er3+-EDTA complex in aq. soln. This approach allowed the authors to est. that the complex in soln. exists in 95% as the 8-coordinate [Er(EDTA)(H2O)2]- species and in 5% as the 9-coordinate [Er(EDTA)(H2O)3]- ones as well as to calc. the conditional hydration equil. const. (Kaqua) of the reaction: [Er(EDTA)(H2O)3]- ↔ [Er(EDTA)(H2O)2]- + H2O which is rather difficult to det. by using other methods. The Kaqua value is 19 ± 1.
- 79Zhang, J.; Dolg, M. Labile Capping Bonds in Lanthanide(III) Complexes: Shorter and Weaker. J. Phys. Chem. A 2015, 119 (4), 774– 780, DOI: 10.1021/jp511043c79https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitFOgsbnP&md5=50aaf22276bfd6fe7371eb2e6513f189Labile Capping Bonds in Lanthanide(III) Complexes: Shorter and WeakerZhang, Jun; Dolg, MichaelJournal of Physical Chemistry A (2015), 119 (4), 774-780CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)For a wide range of trivalent lanthanide ion coordination complexes of tricapped trigonal prism or monocapped square antiprism configurations, the bonds between the central lanthanide ions and the capping ligands are found to violate Badger's rule: they can get weaker as they get shorter. We demonstrate that this observation originates from the screening and repulsion effect of the prism ligands. Both effects enhance as the elec. field of the central ion or the softness of the prism ligands increases. Thus, for heavier lanthanides, despite the fact that the capping bond could be shorter, it is more efficient to be weakened by the prism ligands, being inherently labile. This concept of "labile capping bonds phenomenon" is then successfully used to interpret many problems in lanthanide(III) hydration, e.g., why the water exchange rate of a lanthanide(III) complex is much higher in a twisted square antiprism than in square antiprism configuration. Thus, the theory proposed in this paper offers new insights in understanding chem. problems.
- 80Quici, S.; Marzanni, G.; Forni, A.; Accorsi, G.; Barigelletti, F. New Lanthanide Complexes for Sensitized Visible and Near-IR Light Emission: Synthesis, 1H NMR, and X-Ray Structural Investigation and Photophysical Properties. Inorg. Chem. 2004, 43 (4), 1294– 1301, DOI: 10.1021/ic035143b80https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXntVaktg%253D%253D&md5=3b31dffdb21a1159ce731a8699e60085New Lanthanide Complexes for Sensitized Visible and Near-IR Light Emission: Synthesis, 1H NMR, and X-ray Structural Investigation and Photophysical PropertiesQuici, Silvio; Marzanni, Giovanni; Forni, Alessandra; Accorsi, Gianluca; Barigelletti, FrancescoInorganic Chemistry (2004), 43 (4), 1294-1301CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)The authors describe the syntheses, the 1H NMR studies in CD3OD and D2O as solvent, the x-ray characterization, and the luminescence properties in D2O soln. of the two complexes EuL and ErL (H3L = I), in which the phenanthroline unit which plays the role of light antenna for the sensitization process of the metal centered luminescence. In a previous report (Inorg. Chem. 2002, 41, 2777), for EuL there are no H2O mols. within the 1st coordination sphere. X-ray and 1H NMR results reported here are consistent with full satn. of the nine coordination sites within the EuL and ErL complexes. These studies provide important details regarding the conformations, square antiprism (SAP) and twisted square antiprism (TSAP), adopted in soln. by these complexes. The luminescence results are consistent with both an effective intersystem crossing (ISC) at the light absorbing phenanthroline unit (λexc = 278 nm) and an effective energy transfer (en) process from the phenanthroline donor to the cation acceptor (with unit or close to unit efficiency for both steps). In D2O solvent, the overall sensitization efficiency, φse, is 0.3 and 5 × 10-6, for EuL (main luminescence peaks at 585, 612, 699 nm) and ErL (luminescence peak at 1530 nm), resp. The photophys. properties of both complexes are discussed with ref. to their structural features as elucidated by the obtained 1H NMR and x-ray results.
- 81Storm Thomsen, M.; Andersen, H. O. B.; So̷rensen, T. J. Long Story Short: Donor Set Symmetry in [Eu(DOTA)(H2O)]− Crystals Determines the Electronic Structure. Dalton Trans. 2022, 51 (37), 14118– 14124, DOI: 10.1039/D2DT02172B81https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xit12qtbfF&md5=1107ad17412ec2e854b555bc9aa17513Long story short: donor set symmetry in [Eu(DOTA)(H2O)]- crystals determines the electronic structureStorm Thomsen, Maria; Andersen, Helene Obel Boech; Soerensen, Thomas JustDalton Transactions (2022), 51 (37), 14118-14124CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)Lanthanide complexes of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid DOTA have been studied in great detail due to their use as MRI contrast agents. Since the first report from Desreux in 1980, the Ln[DOTA]- complexes of gadolinium(III) in particular have been thoroughly investigated. The forms of the nine-coordinated [Ln(DOTA)(H2O)]- complexes are well known, and the ligand backbone has been used extensively to create functional MRI contrast agents, luminescent probes, and as a model system for studying the properties of lanthanide(III) ions. In soln., the photophys. properties have been mapped, but as the structures are not known, direct structure-property relationships have not been created. Here, the electronic properties of two Eu[DOTA] compds. (1 and 2) and a Eu[DOTA]-like compd. (3) were studied using single-crystal luminescence spectroscopy. The donor set in the three compds. is identical (4N 4O 1O), and using the symmetry deviation value σ-ideal it was shown that the coordination geometry is close to identical. Nevertheless, the electronic properties evaluated using the luminescence spectrum were found to differ significantly between the three compds. The magnitude of the crystal field splitting was found not to scale with the symmetry of the coordination geometry. It was concluded that the donor set dictates the splitting, yet the structure-property relationships governing the electronic properties of europium(III) ions still elude us.
- 82Howard, J. A. K.; Kenwright, A. M.; Moloney, J. M.; Parker, D.; Woods, M.; Howard, J. A. K.; Port, M.; Navet, M.; Rousseau, O. Structure and Dynamics of All of the Stereoisomers of Europium Complexes of Tetra(Carboxyethyl) Derivatives of Dota: Ring Inversion Is Decoupled from Cooperative Arm Rotation in the RRRR and RRRS Isomers. Chem. Commun. 1998, 13, 1381– 1382, DOI: 10.1039/a802847hThere is no corresponding record for this reference.
- 83Janicki, R.; Mondry, A. Structural and Thermodynamic Aspects of Hydration of Gd(iii) Systems. Dalton Trans. 2019, 48 (10), 3380– 3391, DOI: 10.1039/C8DT04869J83https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXjtlWgurw%253D&md5=d7e7dce566397d2e17dea7f1cf2a77a8Structural and thermodynamic aspects of hydration of Gd(III) systemsJanicki, Rafal; Mondry, AnnaDalton Transactions (2019), 48 (10), 3380-3391CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)X-ray crystal structures of Gd(III) and Lu(III) aqua ions as well as their complexes with polyaminopolycarboxylates (EDTA, CDTA, EGTA, DTPA, DOTA) were detd.: [Gd(H2O)9](CF3SO3)3, [Gd(H2O)8]Cl3·C10H20O5, [Lu(H2O)8]Cl3·C12H24O6·4H2O, [C(NH2)3][Gd(EDTA)(H2O)3], [C(NH2)3]2[Lu(EDTA)(H2O)2]ClO4·6H2O, [C(NH2)3][Lu(CDTA)(H2O)2]·6H2O, [C(NH2)3][Gd(EGTA)(H2O)]·2H2O, [C(NH2)2(N2H4)][Gd(HDTPA)(H2O)]·2H2O, Na[Gd(DOTA)(H2O)]·4H2O, and K2[Lu(DOTA)]Cl·4.6H2O. The weighted sums of UV absorption spectra of appropriate crystals were used to reproduce the spectra of the Gd(III) aq. solns. in the temp. range 276-363 K. In aq. soln. the Gd(III)-EGTA, Gd(III)-DTPA and Gd(III)-DOTA complexes exist as almost pure monohydrate [GdL(H2O)]n- species, while in the case of the Gd(III) aqua ion, Gd(III)-EDTA and Gd(III)-CDTA systems the equil. between variously hydrated species were found. The derived molar fractions of these species were used to det. the ΔG, ΔH and ΔS of hydration. These thermodn. functions may be derived not only from the spectra of the hypersensitive transitions, but from other f-f transitions as well. Next the ΔG, ΔH and ΔS values of hydration for the other Ln(III)-EDTA systems (Ln = Pr, Nd, Sm, Eu) were detd. The ΔG298 values of the dehydration reaction for Ln(III)-EDTA complexes (Ln = Pr, Nd, Sm, Eu, Gd, Ho, Er) were almost linearly dependent on the no. of 4f electrons in the whole series of lanthanides. Also, the point, where the ratio of [LnL(H2O)n] : [LnL(H2O)n-1] is 1, shifts along the lanthanide series depending on the ligand denticity - the higher the ligand denticity, the farther the point of the equimolar ratio in the lanthanide series. The presented results are the 1st systematic exptl. study on the thermodn. description of the hydration equil. of Gd(III) compds.
- 84Kriemen, E.; Holzapfel, M.; Ruf, E.; Rehbein, J.; Maison, W. Synthesis and Structural Analysis of 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraazidoethylacetic Acid (DOTAZA) Complexes. Eur. J. Inorg. Chem. 2015, 2015 (32), 5368– 5378, DOI: 10.1002/ejic.20150078984https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhslWksrrL&md5=d30e083cfe1d11fdc8c803ed5ec70108Synthesis and Structural Analysis of 1,4,7,10-Tetraazacyclododecane-1,4,7,10--tetraazidoethylacetic Acid (DOTAZA) ComplexesKriemen, Ella; Holzapfel, Malte; Ruf, Erik; Rehbein, Julia; Maison, WolfgangEuropean Journal of Inorganic Chemistry (2015), 2015 (32), 5368-5378CODEN: EJICFO; ISSN:1434-1948. (Wiley-VCH Verlag GmbH & Co. KGaA)Herein, the authors present the synthesis and structural anal. of metal complexes of enantiomerically pure 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraazidoethylacetic acid (DOTAZA, I). DOTAZA is a new tunable analog of DOTA, a clin. approved chelator for various pharmaceutically relevant metal ions. The authors study the complexation chem. of DOTAZA and report the crystal structures of a no. of complexes with pharmaceutically relevant metal ions such as Gd3+ [magnetic resonance imaging (MRI)], Eu3+ (luminescence spectroscopy), Y3+ [positron emission tomog. (PET)], In3+ [single-photon-emission computed tomog. (SPECT)], and Na+. These structures provide useful information for imaging applications and demonstrate the potential of DOTAZA to form stable complexes. Owing to its clickable azide functionalities, it may be used for the development of tailored imaging reagents that retain the pos. complexation chem. of the parent compd. DOTA.
- 85Siega, P.; Wuerges, J.; Arena, F.; Gianolio, E.; Fedosov, S. N.; Dreos, R.; Geremia, S.; Aime, S.; Randaccio, L. Release of Toxic Gd3+ Ions to Tumour Cells by Vitamin B12 Bioconjugates. Chem. – Eur. J. 2009, 15 (32), 7980– 7989, DOI: 10.1002/chem.20080268085https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXps1yrsbo%253D&md5=17a522233ac8a25cfce574857852fc66Release of Toxic Gd3+ Ions to Tumour Cells by Vitamin B12 BioconjugatesSiega, Patrizia; Wuerges, Jochen; Arena, Francesca; Gianolio, Eliana; Fedosov, Sergey N.; Dreos, Renata; Geremia, Silvano; Aime, Silvio; Randaccio, LucioChemistry - A European Journal (2009), 15 (32), 7980-7989, S7980/1-S7980/7CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Two probes consisting of vitamin B12 (CNCbl) conjugated to Gd chelates by esterification of the ribose 5'-OH moiety, Gd-DTPA-CNCbl (1; DTPA= diethylenetriamine-N,N,N',N'',N''-pentaacetic acid) and Gd-TTHA-CNCbl (2; TTHA= triethylenetetramine-N,N,N',N'',N''',N'''-hexaacetic acid), have been synthesized and characterized. The crystal structure of a dimeric form of 1, obtained by crystn. with an excess of GdCl3, has been detd. The kinetics of binding to and dissocn. from transcobalamin II show that 1 and 2 maintain high-affinity binding to the vitamin B12 transport protein. Complex 2 is very stable with respect to Gd3+ release owing to the satd. co-ordination of the Gd3+ ion by four amino and five carboxylate groups. Hydrolysis of the ester functionality occurs on the time scale of several hours. The lack of satn. and the possible involvement of the ester functionality in co-ordination result in lower stability of 1 towards hydrolysis and in a considerable release of Gd3+ in vitro. Gd3+ ions released from 1 are avidly taken up by the K562 tumor cells to an extent corresponding to approx. 1010 Gd3+ per cell. The internalization of toxic Gd3+ ions causes a marked decrease in cell viability as assessed by Trypan blue and WST-1 tests. On the contrary, the expts. with the more stable 2 did not show any significant cell internalization of Gd3+ ions and any influence on cell viability. The results point to new avenues of in situ generation of cytotoxic pathways based on the release of toxic Gd3+ ions by vitamin B12 bioconjugates.
- 86Campello, M. P. C.; Lacerda, S.; Santos, I. C.; Pereira, G. A.; Geraldes, C. F. G. C.; Kotek, J.; Hermann, P.; Vaněk, J.; Lubal, P.; Kubíček, V.; Tóth, É.; Santos, I. Lanthanide(III) Complexes of 4,10-Bis(Phosphonomethyl)-1,4,7,10-Tetraazacyclododecane-1,7-Diacetic Acid (Trans-H6do2a2p) in Solution and in the Solid State: Structural Studies Along the Series. Chem. – Eur. J. 2010, 16 (28), 8446– 8465, DOI: 10.1002/chem.20100032086https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXptlejtbg%253D&md5=dfc3cf9d059089ca3cf7c33340b8850cLanthanide(III) Complexes of 4,10-Bis(phosphonomethyl)-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (trans-H6do2a2p) in Solution and in the Solid State: Structural Studies Along the SeriesCampello, M. Paula C.; Lacerda, Sara; Santos, Isabel C.; Pereira, Giovannia A.; Geraldes, Carlos F. G. C.; Kotek, Jan; Hermann, Petr; Vanek, Jakub; Lubal, Premysl; Kubicek, Vojtech; Toth, Eva; Santos, IsabelChemistry - A European Journal (2010), 16 (28), 8446-8465, S8446/1-S8446/33CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Complexes of 4,10-bis(phosphonomethyl)-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (trans-H6do2a2p, H6L) with transition metal and lanthanide(III) ions were studied. The stability const. values of the divalent and trivalent metal-ion complexes are between the corresponding values of H4dota and H8dotp complexes, as a consequence of the ligand basicity. The solid-state structures of the ligand and of nine lanthanide(III) complexes were detd. by x-ray diffraction. All the complexes are present as twisted-square-antiprismatic isomers and their structures can be divided into two series. The first one involves nonacoordinated complexes of the large lanthanide(III) ions (Ce, Nd, Sm) with a coordinated H2O mol. For Sm, Eu, Tb, Dy, Er, Yb, the complexes are octacoordinated only by the ligand donor atoms and their coordination cages are more irregular. The formation kinetics and the acid-assisted dissocn. of several LnIII-H6L complexes were studied at different temps. and compared with analogous data for complexes of other dota-like ligands. The [Ce(L)(H2O)]3- complex is the most kinetically inert among complexes of the studied lanthanide(III) ions (Ce, Eu, Gd, Yb). Among mixed phosphonate-acetate dota analogs, kinetic inertness of the Ce(III) complexes is increased with a higher no. of phosphonate arms in the ligand, whereas the opposite is true for Eu(III) complexes. According to the 1H NMR spectroscopic pseudo-contact shifts for the Ce-Eu and Tb-Yb series, the soln. structures of the complexes reflect the structures of the [Ce(HL)(H2O)]2- and [Yb(HL)]2- anions, resp., found in the solid state. However, these soln. NMR spectroscopic studies showed that there is no unambiguous relation between 31P/1H lanthanide-induced shift (LIS) values and coordination of H2O in the complexes; the values rather express a relative position of the central ions between the N4 and O4 planes.
- 87Vojtíšek, P.; Cígler, P.; Kotek, J.; Rudovský, J.; Hermann, P.; Lukeš, I. Crystal Structures of Lanthanide(III) Complexes with Cyclen Derivative Bearing Three Acetate and One Methylphosphonate Pendants. Inorg. Chem. 2005, 44 (16), 5591– 5599, DOI: 10.1021/ic048190s87https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXmtVWhs74%253D&md5=c7f1952f2c9087e713b32ff0e4a2ba87Crystal Structures of Lanthanide(III) Complexes with Cyclen Derivative Bearing Three Acetate and One Methylphosphonate PendantsVojtisek, Pavel; Cigler, Petr; Kotek, Jan; Rudovsky, Jakub; Hermann, Petr; Lukes, IvanInorganic Chemistry (2005), 44 (16), 5591-5599CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)Lanthanide(III) complexes formulated as M[Ln(Hdo3ap)]·xH2O (M = Li; Ln = Tb, Dy, Lu, Y and M = H; Ln = Er, Lu) with the monophosphonate analog of H4dota, 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic-10-methylphosphonic acid (I; H5do3ap), were prepd. and studied using x-ray crystallog. All of the structures show that the (Hdo3ap)4- anion is octadentate coordinated to a lanthanide(III) ion similarly to the other H4dota-like ligands, i.e., forming O4 and N4 planes that are parallel and have mutual angle smaller than 3°. The lanthanide(III) ions lie between these planes, closer to the O4 base than to the N4 plane. All of the structures present the lanthanide(III) complexes in their twisted-square-antiprismatic (TSA) configuration. Twist angles of the pendants vary in the range between -24 and -30°, and for each complex, they lie in a very narrow region of 1°. The coordinated phosphonate oxygen is located slightly above (0.02-0.19 Å) the O3 plane formed with the coordinated acetates. The Dy, Y and Lu complexes are isostructural and can be formulated as [{Li(H2O)3}{M(Hdo3ap)}]·2H2O. These three complexes have a tetrahedral lithium coordinated only to one acetate O and 3 water mols. A water mol. is coordinated only in the terbium(III) and neodymium(III) complexes. The bond distance Tb-Ow is unusually long (2.678 Å). The O-Ln-O angles decrease from 140° [Nd(III)] to 121° [Lu(III)], thus confirming the increasing steric crowding around the water binding site. A comparison of a no. of structures of Ln(III) complexes with DOTA-like ligands shows that the TSA arrangement is flexible. However, the SA arrangement is rigid, and the derived structural parameters are almost identical for different ligands and lanthanide(III) ions.
- 88Bondi, A. Van Der Waals Volumes and Radii. J. Phys. Chem. 1964, 68 (3), 441– 451, DOI: 10.1021/j100785a00188https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF2cXls1Cgsg%253D%253D&md5=0f25964afae4e9f761e0d314151444a5van der Waals volumes and radiiBondi, A.Journal of Physical Chemistry (1964), 68 (3), 441-51CODEN: JPCHAX; ISSN:0022-3654.Intermol. van der Waals radii of the nonmetallic elements were assembled into a list of recommended values for vol. calcns. These values were arrived at by selecting from the most reliable x-ray diffraction data those which could be reconciled with crystal d. at 0°K. (to give reasonable packing d.), gas kinetic collision cross section, crit. d., and with liquid state properties. A qual. understanding of the nature of van der Waals radii is provided by correlation with the de Broglie wavelength of the outermost valence electron. Tentative values for the van der Waals radii of metallic elements in organometallic compds. are proposed. A list of increments for the vol. of mols. impenetrable to thermal collision, the so-called van der Waals vol., and of the corresponding increments in area per mol. is given.
- 89Rowland, R. S.; Taylor, R. Intermolecular Nonbonded Contact Distances in Organic Crystal Structures: Comparison with Distances Expected from van Der Waals Radii. J. Phys. Chem. 1996, 100 (18), 7384– 7391, DOI: 10.1021/jp953141+89https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28Xit1ykt7k%253D&md5=0308272c8e4653deb3823a27276975c4Intermolecular Nonbonded Contact Distances in Organic Crystal Structures: Comparison with Distances Expected from van der Waals RadiiRowland, R. Scott; Taylor, RobinJournal of Physical Chemistry (1996), 100 (18), 7384-91CODEN: JPCHAX; ISSN:0022-3654. (American Chemical Society)The conclusions derived from systematic analyses of intermol. contact distances in org. crystals may be affected by the values assumed for van der Waals radii. The most widely used tabulations of van der Waals radii date back 30 yr or more. Also, many of the tabulated values were chosen to reproduce vols., not contact distances, in crystals. Literally millions of nonbonded contact distances were characterized by crystallog. since the tabulations were compiled. A study has therefore been performed to establish the degree of consistency between these accumulated crystallog. data and the van der Waals radii of the common nonmetallic elements, as compiled by Pauling and Bondi. For halogens and S, the results show a remarkable agreement between obsd. contact distances and the Bondi radii. Agreement is slightly less good for C, N, and O, but discrepancies are still only ∼0.05 Å. However, there is a significant difference for H, where the Bondi value of 1.2 Å is probably too high by ∼0.1 Å.
- 90Fernández-Fernández, M. D. C.; Bastida, R.; Macías, A.; Pérez-Lourido, P.; Platas-Iglesias, C.; Valencia, L. Lanthanide(III) Complexes with a Tetrapyridine Pendant-Armed Macrocyclic Ligand: 1H NMR Structural Determination in Solution, X-Ray Diffraction, and Density-Functional Theory Calculations. Inorg. Chem. 2006, 45 (11), 4484– 4496, DOI: 10.1021/ic060350890https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XktVSks7k%253D&md5=6d7e0be39ab445ef5ae9dd584d78fba9Lanthanide(III) Complexes with a Tetrapyridine Pendant-Armed Macrocyclic Ligand: 1H NMR Structural Determination in Solution, X-ray Diffraction, and Density-Functional Theory CalculationsFernandez-Fernandez, M. del C.; Bastida, R.; Macias, A.; Perez-Lourido, P.; Platas-Iglesias, C.; Valencia, L.Inorganic Chemistry (2006), 45 (11), 4484-4496CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)Complexes between the tetrapyridyl pendant-armed macrocyclic ligand (L) and the trivalent lanthanide ions were synthesized, and structural studies were made both in the solid state and in aq. soln. The crystal structures of the La, Ce, Pr, Gd, Tb, Er, and Tm complexes were detd. by single-crystal x-ray crystallog. In the solid state, all the cation complexes show a 10-coordinated geometry close to a distorted bicapped antiprism, with the pyridine pendants situated alternatively above and below the main plane of the macrocycle. The conformations of the two five-membered chelate rings present in the complexes change along the lanthanide series. The La(III) and Ce(III) complexes show a λδ (or δλ) conformation, while the complexes of the heavier lanthanide ions present λλ (or δδ) conformation. The cationic [Ln(L)]3+ complexes (Ln = La, Pr, Eu, Tb, and Tm) were also characterized by theor. calcns. at the d.-functional theory (DFT) B3LYP level. The theor. calcns. predict a stabilization of the λλ (or δδ) conformation on decreasing the ionic radius of the Ln(III) ion, in agreement with the exptl. evidence. The soln. structures show a good agreement with the calcd. ones, as demonstrated by paramagnetic NMR measurements (lanthanide induced shifts and relaxation rate enhancements). The 1H NMR spectra indicate an effective D2 symmetry of the complexes in D2O soln. The 1H lanthanide induced shifts (LIS) obsd. for the Ce(III), Tm(III), and Yb(III) complexes can be fit to a theor. model assuming that dipolar contributions are dominant for all protons. The resulting calcd. values are consistent with highly rhombic magnetic susceptibility tensors with the magnetic axes being coincident with the symmetry axes of the mol. In contrast with the solid-state structure, the anal. of the LIS data indicates that the Ce(III) complexes present a λλ (or δδ) conformation in soln.
- 91Castro, G.; Regueiro-Figueroa, M.; Esteban-Gómez, D.; Bastida, R.; Macías, A.; Pérez-Lourido, P.; Platas-Iglesias, C.; Valencia, L. Exceptionally Inert Lanthanide(III) PARACEST MRI Contrast Agents Based on an 18-Membered Macrocyclic Platform. Chem. – Eur. J. 2015, 21 (51), 18662– 18670, DOI: 10.1002/chem.20150293791https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhslyht7zP&md5=2c07436f30ef4a738ee9b4ee7f3232abExceptionally Inert Lanthanide(III) PARACEST MRI Contrast Agents Based on an 18-Membered Macrocyclic PlatformCastro, Goretti; Regueiro-Figueroa, Martin; Esteban-Gomez, David; Bastida, Rufina; Macias, Alejandro; Perez-Lourido, Paulo; Platas-Iglesias, Carlos; Valencia, LauraChemistry - A European Journal (2015), 21 (51), 18662-18670CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)We report a macrocyclic ligand based on a 3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane platform contg. four hydroxyethyl pendant arms (L1) that forms extraordinary inert complexes with Ln3+ ions. The [EuL1]3+ complex does not undergo dissocn. in 1 M HCl over a period of months at room temp. Furthermore, high concns. of phosphate and Zn2+ ions at room temp. do not provoke metal-complex dissocn. The X-ray crystal structures of six Ln3+ complexes reveal ten coordination of the ligand to the metal ions through the six nitrogen atoms of the macrocycle and the four oxygen atoms of the hydroxyethyl pendant arms. The anal. of the Yb3+- and Pr3+-induced paramagnetic 1H NMR shifts show that the solid-state structures are retained in aq. soln. The intensity of the 1H NMR signal of bulk water can be modulated by satn. of the signals of the hydroxy protons of Pr3+, Eu3+, and Yb3+ complexes following chem.-exchange satn. transfer (CEST). The ability of these complexes to provide large CEST effects at 25 and 37 °C and pH 7.4 was confirmed by using CEST magnetic resonance imaging expts.
- 92Xing, Y.; Jindal, A. K.; Regueiro-Figueroa, M.; Le Fur, M.; Kervarec, N.; Zhao, P.; Kovacs, Z.; Valencia, L.; Pérez-Lourido, P.; Tripier, R.; Esteban-Gómez, D.; Platas-Iglesias, C.; Sherry, A. D. The Relationship between NMR Chemical Shifts of Thermally Polarized and Hyperpolarized 89Y Complexes and Their Solution Structures. Chem. – Eur. J. 2016, 22 (46), 16657– 16667, DOI: 10.1002/chem.20160290192https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xhs1ClsLvN&md5=8f9701d055a6e3e2928a34694bea4b7cThe Relationship between NMR Chemical Shifts of Thermally Polarized and Hyperpolarized 89Y Complexes and Their Solution StructuresXing, Yixun; Jindal, Ashish K.; Regueiro-Figueroa, Martin; Le Fur, Mariane; Kervarec, Nelly; Zhao, Piyu; Kovacs, Zoltan; Valencia, Laura; Perez-Lourido, Paulo; Tripier, Raphael; Esteban-Gomez, David; Platas-Iglesias, Carlos; Sherry, A. DeanChemistry - A European Journal (2016), 22 (46), 16657-16667CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)Recently developed dynamic nuclear polarization (DNP) technol. offers the potential of increasing the NMR sensitivity of even rare nuclei for biol. imaging applications. Hyperpolarized 89Y is an ideal candidate because of its narrow NMR linewidth, favorable spin quantum no. (I=1/2), and long longitudinal relaxation times (T1). Strong NMR signals were detected in hyperpolarized 89Y samples of a variety of yttrium complexes. A dataset of 89Y NMR data composed of 23 complexes with polyaminocarboxylate ligands was obtained using hyperpolarized 89Y measurements or 1H,89Y-HMQC spectroscopy. These data were used to derive an empirical equation that describes the correlation between the 89Y chem. shift and the chem. structure of the complexes. This empirical correlation serves as a guide for the design of 89Y sensors. Relativistic (DKH2) DFT calcns. were found to predict the exptl. 89Y chem. shifts to a rather good accuracy.
- 93Gambino, T.; Valencia, L.; Pérez-Lourido, P.; Esteban-Gómez, D.; Zaiss, M.; Platas-Iglesias, C.; Angelovski, G. Inert Macrocyclic Eu 3+ Complex with Affirmative paraCEST Features. Inorg. Chem. Front. 2020, 7 (12), 2274– 2286, DOI: 10.1039/C9QI01612K93https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXkvF2ltb4%253D&md5=4ed575859e442f900794501d32ceffdaInert macrocyclic Eu3+ complex with affirmative paraCEST featuresGambino, Tanja; Valencia, Laura; Perez-Lourido, Paulo; Esteban-Gomez, David; Zaiss, Moritz; Platas-Iglesias, Carlos; Angelovski, GoranInorganic Chemistry Frontiers (2020), 7 (12), 2274-2286CODEN: ICFNAW; ISSN:2052-1553. (Royal Society of Chemistry)We report on a macrocyclic platform based on an 18-membered macrocycle that forms kinetically highly inert paramagnetic complexes and possesses an excellent outlook for the development of bioresponsive paraCEST (paramagnetic chem. exchange satn. transfer) contrast agents. The investigated europium(III) chelate is non-hydrated and contains four amide groups, each possessing two paramagnetically shifted proton resonances distant from bulk water. The X-ray crystal structure and soln. studies indicate that the metal ion is ten-coordinated, being directly bound to the six N atoms of the macrocycle and the four amide O atoms of the pendant arms. The complex presents an excellent inertness with respect to dissocn., being stable under a variety of harsh conditions, including highly acidic and basic media or elevated temps. The amide protons are in slow-to-intermediate exchange with bulk water, which gives rise to the generation of a strong CEST effect at low probe concn. and satn. powers (~ 25% at 5 mM, B1 = 5 μT, 37 °C). We demonstrate the potential of this platform for mapping pH in its microenvironment and foresee potential for the development of diverse paraCEST probes and sensors.
- 94Harriswangler, C.; Caneda-Martínez, L.; Rousseaux, O.; Esteban-Gómez, D.; Fougère, O.; Pujales-Paradela, R.; Valencia, L.; Fernández, M. I.; Lepareur, N.; Platas-Iglesias, C. Versatile Macrocyclic Platform for the Complexation of [natY/90Y]Yttrium and Lanthanide Ions. Inorg. Chem. 2022, 61 (16), 6209– 6222, DOI: 10.1021/acs.inorgchem.2c0037894https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XpslajtLg%253D&md5=d1aa14660f7c9375e85d415b5ef686b1Versatile Macrocyclic Platform for the Complexation of [natY/90Y]Yttrium and Lanthanide IonsHarriswangler, Charlene; Caneda-Martinez, Laura; Rousseaux, Olivier; Esteban-Gomez, David; Fougere, Olivier; Pujales-Paradela, Rosa; Valencia, Laura; Fernandez, M. Isabel; Lepareur, Nicolas; Platas-Iglesias, CarlosInorganic Chemistry (2022), 61 (16), 6209-6222CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)We report a macrocyclic ligand (H3L6) based on a 3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane platform contg. three acetate pendant arms and a benzyl group attached to the fourth nitrogen atom of the macrocycle. The X-ray structures of the YL6 and TbL6 complexes reveal nine coordination of the ligand to the metal ions through the six nitrogen atoms of the macrocycle and three oxygen atoms of the carboxylate pendants. A combination of NMR spectroscopic studies (1H, 13C, and 89Y) and DFT calcns. indicated that the structure of the YL6 complex in the solid state is maintained in an aq. soln. The detailed study of the emission spectra of the EuL6 and TbL6 complexes revealed Ln3+-centered emission with quantum yields of 7.0 and 60%, resp. Emission lifetime measurements indicate that the ligand offers good protection of the metal ions from surrounding water mols., preventing the coordination of water mols. The YL6 complex is remarkably inert with respect to complex dissocn., with a lifetime of 1.7 h in 1 M HCl. On the other hand, complex formation is fast (~ 1 min at pH 5.4, 2 × 10-5 M). Studies using the 90Y-nuclide confirmed fast radiolabeling since [90Y]YL6 is nearly quant. formed (radiochem. yield (RCY) > 95) in a short time over a broad range of pH values from ca. 2.4 to 9.0. Challenging expts. in the presence of excess EDTA and in human serum revealed good stability of the [90Y]YL6 complex. All of these expts. combined suggest the potential application of H3L6 derivs. as Y-based radiopharmaceuticals.
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Computational details, crystallographic data (CCDC 2266985), additional plots showing calculated electron densities, linear fits according to eq 1, and bond distances used in this work with CSD codes (PDF)
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