Quasi-Elastic Neutron Scattering of Citrate-Capped Iron Oxide Nanoparticles: Distinguishing between Ligand, Water, and Magnetic DynamicsClick to copy article linkArticle link copied!
- Maksim S. PlekhanovMaksim S. PlekhanovInstitute of Crystallography, RWTH Aachen University, Jägerstrasse 17-19, Aachen 52066, GermanyMore by Maksim S. Plekhanov
- Sabrina L. J. ThomäSabrina L. J. ThomäInstitute of Crystallography, RWTH Aachen University, Jägerstrasse 17-19, Aachen 52066, GermanyCenter for X-ray Analytics, Empa−Swiss Federal Laboratories for Materials, Science, and Technology, Überlandstrasse 129, Dübendorf CH-8600, SwitzerlandMore by Sabrina L. J. Thomä
- Andreas MagerlAndreas MagerlDepartment of Physics, Friedrich-Alexander University, Biophysics Group, Henkestraße 91, Erlangen 91052, GermanyJCNS-3: Neutron Analytics for Energy Research, Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, Jülich 52428, GermanyMore by Andreas Magerl
- Markus AppelMarkus AppelInstitut Laue-Langevin, 71 avenue des Martyrs, CS 20156, Grenoble Cedex 9 38042, FranceMore by Markus Appel
- Mirijam Zobel*Mirijam Zobel*Email: [email protected]JCNS-3: Neutron Analytics for Energy Research, Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, Jülich 52428, GermanyInstitute of Crystallography, RWTH Aachen University, Jägerstrasse 17-19, Aachen 52066, GermanyMore by Mirijam Zobel
Abstract
Experimental access to the diffusional properties of organic ligand molecules on nanoparticle (NP) surfaces is scarce, although surface functionalization is widespread in synthesis and for the control of functional particle properties. This work focuses on the dynamics of citrate ligands and water molecules on the surface of 6 nm iron oxide NPs (IONPs) equilibrated at a relative humidity of 8% by quasi-elastic neutron scattering. Given the complex quasi-elastic scattering signal including the magnetic nature of the IONPs, we build on fixed window scans to separate multiple dynamic processes, namely, phonons, magnetic relaxations, and hydrogen dynamics. In addition, deuterated samples allowed us to separate the ligand and water dynamics. With a simultaneous fit approach, multiple fixed window scans and energy-resolved spectra are described to determine the activation energies and relaxation times. It is found that surface-bound citrate ligands rotate continuously with Ea = 240 meV and τ0 = 0.21 ps, while surface water diffuses translationally with Ea = 190 meV and τ0 = 0.12 ps, significantly slower than bulk water. The separation of the coexisting dynamic processes in this study proves the high potential of quasi-elastic neutron scattering to reach a detailed understanding of interfacial processes in nanostructured materials.
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Introduction
NPs | ligand | motion type | relaxation time, ps (T of measurement) | activation energy, meV | reference |
---|---|---|---|---|---|
FexOy | oleic acid (C18H34O2) | uniaxial rotation | 370 (300 K) | 34.2 | (27) |
polyisoprene (C5H8)n | segmental dynamicsa | ∼2 × 103 (300 K) | (28) | ||
SiO2 | polymethyl acrylate (C4H6O2)n | jump diffusion | 50 (420 K) | 207 | (29) |
PbS | dodecanethiol (C12H26S) | uniaxial rotation | 220 (300 K) | 82.9 | (25) |
hexanedithiol (C6H14S2) | uniaxial rotation | 390 (300 K) | 135.0 | ||
Au | hexanethiolate (C6H13S) | uniaxial rotation | 2.8 (360 K) | 117.1 | (30) |
octadecanethiolate (C18H37S) | uniaxial rotation | 1.5 (360 K) | 273.2 |
Nondiffusive relaxations of a group of bonded atoms within a polymer chain. (31).
Methods
Sample Synthesis
Sample Characterization: Water and Ligand Content
QENS and Neutron Powder Diffraction Measurements
QENS Data Analysis
Results and Discussion
Sample Characterization
FWSs in Magnetic and Nonmagnetic Regions
Figure 1
Figure 1. (a) Intensity at 2, 120, and 300 K from the EFWS, plotted along with the NPD pattern of IONPs measured at RT; (b) intensity at the energy offset of 3 μeV and temperatures of 5, 120, and 300 K.
i | Q < 0.43 Å–1 (detectors Q0–Q2)─affected by small-angle scattering; | ||||
ii | 0.43 < Q < 1.12 Å–1 (Q3–Q6) and 1.47 < Q < 1.79 Å–1 (Q12–Q16)─scattering mostly from nuclei in the sample; hereinafter referred to as the non-Bragg region; | ||||
iii | 1.12 < Q < 1.47 Å–1 (Q7–Q11) main magnetic Bragg peak; hereinafter referred to as the Bragg region. |
Figure 2
1 | a low-temperature magnetic process for all Q values; (27,28) | ||||
2 | this magnetic process is either amplified or accompanied in the magnetic Bragg region by a second low-temperature contribution; | ||||
3 | a high-temperature process well visible across all Q values at temperatures above 200 K. This process is likely related to the motion of hydrogen atoms belonging to ligands and/or water. |
ERS Distinguishing Citrate and Water Motion
Figure 3
Figure 3. ERS measured at 360 K at IN16B in BATS mode for an H2O-equilibrated (a) and at 370 K on the BS Emu for a D2O-equilibrated sample (b).
Unifying Picture of Dynamics by Simultaneous Fit of the FWS and ERS
Figure 4
Figure 4. Simultaneous fit of the EFWS (a), IFWS (b), and ERS at 340 (c) and 380 K (d).
fit parameter | value (340 K) | value (380 K) |
---|---|---|
Aeff0, [a.u.] | 0.64 ± 0.06 | 0.56 ± 0.05 |
Aeffcit, [a.u.] | 0.61 ± 0.20 | 0.59 ± 0.23 |
τ0cit, [ps] | 0.21 ± 0.40 | 0.21 ± 0.40 |
Eacit, [meV] | 239 ± 12 | 239 ± 12 |
Γcalccit, [meV] | 0.001 ± 0.004 | 0.002 ± 0.009 |
Aeffwater, [a.u.] | 0.19 ± 0.13 | 0.23 ± 0.10 |
τ0water, [ps] | 0.12 ± 0.27 | 0.12 ± 0.27 |
Eawater, [meV] | 189 ± 7 | 189 ± 7 |
Γcalcwater, [meV] | 0.009 ± 0.019 | 0.017 ± 0.039 |
Aeffmag, [a.u.] | 0.21 ± 0.13 | 0.22 ± 0.17 |
τ0mag, [ps] | 50.46 ± 23.48 | 50.46 ± 23.48 |
Eamag, [meV] | 34 ± 2 | 34 ± 2 |
Γcalcmag, [meV] | 0.004 ± 0.002 | 0.005 ± 0.002 |
θD, [K] | 382.18 ± 0.07 | 0.07 |
Figure 5
Figure 5. (a) Activation energy and relaxation time limit of citrate motion; (b) HWHM of citrate Lorentzian from H2O- and D2O-equilibrated samples (370 K); (c) HWHM and the amplitude of water Lorentzian from simultaneous fit (360 K).
Figure 6
Figure 6. Amplitudes of the Lorentzian describing citrate motion fitted with continuous diffusion on a circle.
Conclusions
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.jpcc.4c00479.
Sample characterization, detector bank numbers and corresponding Q values, neutron powder diffraction, model equations, logarithmic-scale QENS plots, and magnetic relaxation (PDF)
Terms & Conditions
Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.
Acknowledgments
We acknowledge funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) via ZO 369/3-1, as well as RWTH Aachen University for the special commitment scholarship (STIBET I). We acknowledge beamtimes EASY-636, INTER-528, and 9-12-648 at IN16B (ILL) and beamtime ID 13387 at Emu (ANSTO). We thank the respective beamline scientists A. Klapproth (ANSTO) and N. De Souza (ANSTO) for assistance in operating the instruments. Furthermore, we acknowledge R. Zorn, JCNS-1, Forschungszentrum Jülich, for discussion, as well as B. Frick, ILL. We acknowledge support from M. Schwarzmann and A. Dietel for TGA and CHN analytics. We are grateful to M. Dulle, JCNS-1, Forschungszentrum Jülich, for SAXS measurements.
References
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- 2Amstad, E.; Textor, M.; Reimhult, E. Stabilization and Functionalization of Iron Oxide Nanoparticles for Biomedical Applications. Nanoscale 2011, 3 (7), 2819, DOI: 10.1039/c1nr10173kGoogle Scholar2https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXptVahsLc%253D&md5=6d60b836b1b9c9a582219173529e128eStabilization and functionalization of iron oxide nanoparticles for biomedical applicationsAmstad, Esther; Textor, Marcus; Reimhult, ErikNanoscale (2011), 3 (7), 2819-2843CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)A review. Superparamagnetic iron oxide nanoparticles (NPs) are used in a rapidly expanding no. of research and practical applications in the biomedical field, including magnetic cell labeling sepn. and tracking, for therapeutic purposes in hyperthermia and drug delivery, and for diagnostic purposes, e.g., as contrast agents for magnetic resonance imaging. These applications require good NP stability at physiol. conditions, close control over NP size and controlled surface presentation of functionalities. This review is focused on different aspects of the stability of superparamagnetic iron oxide NPs, from its practical definition to its implementation by mol. design of the dispersant shell around the iron oxide core and further on to its influence on the magnetic properties of the superparamagnetic iron oxide NPs. Special attention is given to the selection of mol. anchors for the dispersant shell, because of their importance to ensure colloidal and functional stability of sterically stabilized superparamagnetic iron oxide NPs. The authors further detail how dispersants were optimized to gain close control over iron oxide NP stability, size and functionalities by independently considering the influences of anchors and the attached sterically repulsive polymer brushes. A crit. evaluation of different strategies to stabilize and functionalize core-shell superparamagnetic iron oxide NPs as well as a brief introduction to characterization methods to compare those strategies is given.
- 3Vangijzegem, T.; Stanicki, D.; Laurent, S. Magnetic Iron Oxide Nanoparticles for Drug Delivery: Applications and Characteristics. Expert Opin. Drug Delivery 2019, 16 (1), 69– 78, DOI: 10.1080/17425247.2019.1554647Google Scholar3https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXisVKitLzF&md5=6c7ea014c0d99a2820229cd9e3b77dc6Magnetic iron oxide nanoparticles for drug delivery: applications and characteristicsVangijzegem, Thomas; Stanicki, Dimitri; Laurent, SophieExpert Opinion on Drug Delivery (2019), 16 (1), 69-78CODEN: EODDAW; ISSN:1742-5247. (Taylor & Francis Ltd.)A review. : For many years, the controlled delivery of therapeutic compds. has been a matter of great interest in the field of nanomedicine. Among the wide amt. of drug nanocarriers, magnetic iron oxide nanoparticles (IONs) stand out from the crowd and constitute robust nanoplatforms since they can achieve high drug loading as well as targeting abilities stemming from their remarkable properties (magnetic and biol. properties). These applications require precise design of the nanoparticles regarding several parameters which must be considered together in order to attain highest therapeutic efficacy.: This short review presents recent developments in the field of cancer targeted drug delivery using magnetic nanocarriers as drug delivery systems.: The design of nanocarriers enabling efficient delivery of therapeutic compds. toward targeted locations is one of the major area of research in the targeted drug delivery field. By precisely shaping the structural properties of the iron oxide nanoparticles, drugs loaded onto the nanoparticles can be efficiently guided and selectively delivered toward targeted locations. With these goals in mind, special attention should be given to the pharmacokinetics and in vivo behavior of the developed nanocarriers.
- 4Oehlsen, O.; Cervantes-Ramírez, S. I.; Cervantes-Avilés, P.; Medina-Velo, I. A. Approaches on Ferrofluid Synthesis and Applications: Current Status and Future Perspectives. ACS Omega 2022, 7 (4), 3134– 3150, DOI: 10.1021/acsomega.1c05631Google Scholar4https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhsF2ks7Y%253D&md5=05058713a3a8d2acaf9413ea8fbd9f7fApproaches on Ferrofluid Synthesis and Applications: Current Status and Future PerspectivesOehlsen, Oscar; Cervantes-Ramirez, Sussy I.; Cervantes-Aviles, Pabel; Medina-Velo, Illya A.ACS Omega (2022), 7 (4), 3134-3150CODEN: ACSODF; ISSN:2470-1343. (American Chemical Society)A review. Ferrofluids are colloidal suspensions of iron oxide nanoparticles (IONPs) within aq. or nonaq. liqs. that exhibit strong magnetic properties. These magnetic properties allow ferrofluids to be manipulated and controlled when exposed to magnetic fields. This review aims to provide the current scope and research opportunities regarding the methods of synthesis of nanoparticles, surfactants, and carrier liqs. for ferrofluid prodn., along with the rheol. and applications of ferrofluids within the fields of medicine, water treatment, and mech. engineering. A ferrofluid is composed of IONPs, a surfactant that coats the magnetic IONPs to prevent agglomeration, and a carrier liq. that suspends the IONPs. Copptn. and thermal decompn. are the main methods used for the synthesis of IONPs. Despite the fact that thermal decompn. provides precise control on the nanoparticle size, copptn. is the most used method, even when the oxidn. of iron can occur. This oxidn. alters the ratio of maghemite/magnetite, influencing the magnetic properties of ferrofluids. Strategies to overcome iron oxidn. have been proposed, such as the use of an inert atm., adjusting the Fe(II) and Fe(III) ratio to 1:2, and the exploration of other metals with the oxidn. state +2. Surfactants and carrier liqs. are chosen according to the ferrofluid application to ensure stability. Hence, a compatible carrier liq. (polar or nonpolar) is selected, and then, a surfactant, mainly a polymer, is embedded in the IONPs, providing a steric barrier. Due to the variety of surfactants and carrier liqs., the rheol. properties of ferrofluids are an important response variable evaluated when synthesizing ferrofluids. There are many reported applications of ferrofluids, including biosensing, medical imaging, medicinal therapy, magnetic nanoemulsions, and magnetic impedance. Other applications include water treatment, energy harvesting and transfer, and vibration control. To progress from synthesis to applications, research is still ongoing to ensure control of the ferrofluids' properties.
- 5Saraswathy, A.; Nazeer, S. S.; Jeevan, M.; Nimi, N.; Arumugam, S.; Harikrishnan, V. S.; Varma, P. H.; Jayasree, R. S. Citrate Coated Iron Oxide Nanoparticles with Enhanced Relaxivity for in Vivo Magnetic Resonance Imaging of Liver Fibrosis. Colloids Surf., B 2014, 117, 216– 224, DOI: 10.1016/j.colsurfb.2014.02.034Google Scholar5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXntFynurs%253D&md5=f566d22cb9e25fb6162627fa2e1c216cCitrate coated iron oxide nanoparticles with enhanced relaxivity for in vivo magnetic resonance imaging of liver fibrosisSaraswathy, Ariya; Nazeer, Shaiju S.; Jeevan, Madhumol; Nimi, Nirmala; Arumugam, Sabareeswaran; Harikrishnan, Vijayakumar S.; Varma, P. R. Harikrishna; Jayasree, Ramapurath S.Colloids and Surfaces, B: Biointerfaces (2014), 117 (), 216-224CODEN: CSBBEQ; ISSN:0927-7765. (Elsevier B.V.)Superparamagnetic iron oxide nanoparticles are widely used for the magnetic resonance imaging (MRI) applications. The surface characteristics, magnetic properties, size and targeting efficiency of the material are crucial factors for using the same as contrast agents. We report a simple synthesis method of citrate coated iron oxide nanoparticles and its systematic characterization. The developed system is highly water dispersible with an av. particle size of 12 nm. The particles in water are monodisperse and are found to be stable over long periods. The efficiency of the material to de-phase water proton has been studied for various concns. of iron using longitudinal (T1) and transverse (T2) weighted MRI. The coating thickness of the nanoparticle was optimized so that they exhibited a high transverse to longitudinal relaxivity (r2/r1) ratio of 37.92. A clear dose-dependent contrast enhancement was obsd. in T2 weighted in vivo MR imaging of liver fibrosis model in rodents. The labeling efficacy of the particle and the intracellular magnetic relaxivity were also investigated and presented. The particles were also tested for blood and cellular compatibility studies. Development of fibrosis and presence of iron in the liver was confirmed by histopathol. anal. From this study, we conclude that the citrate coated ultra small superparamagnetic iron oxide nanoparticles (C-USPION) with optimized parameters like particle size and magnetic property are capable of producing good MR contrast in imaging of liver diseases.
- 6Abo-zeid, Y.; Ismail, N. S. M.; McLean, G. R.; Hamdy, N. M. A Molecular Docking Study Repurposes FDA Approved Iron Oxide Nanoparticles to Treat and Control COVID-19 Infection. Eur. J. Pharm. Sci. 2020, 153, 105465, DOI: 10.1016/j.ejps.2020.105465Google Scholar6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsVWgsL3F&md5=2f7c5e2b2fd7ec34245b50df5744ef49A molecular docking study repurposes FDA approved iron oxide nanoparticles to treat and control COVID-19 infectionAbo-zeid, Yasmin; Ismail, Nasser. S.; McLean, Gary. R.; Hamdy, Nadia. M.European Journal of Pharmaceutical Sciences (2020), 153 (), 105465CODEN: EPSCED; ISSN:0928-0987. (Elsevier B.V.)COVID-19, is a disease resulting from the SARS-CoV-2 global pandemic. Due to the current global emergency and the length of time required to develop specific antiviral agent(s) and a vaccine for SARS-CoV-2, the world health organization (WHO) adopted the strategy of repurposing existing medications to treat COVID-19. Iron oxide nanoparticles (IONPs) were previously approved by the US food and drug administration (FDA) for anemia treatment and studies have also demonstrated its antiviral activity in vitro. Therefore, we performed a docking study to explore the interaction of IONPs (Fe2O3 and Fe3O4) with the spike protein receptor binding domain (S1-RBD) of SARS-CoV-2 that is required for virus attachment to the host cell receptors. A similar docking anal. was also performed with hepatitis C virus (HCV) glycoproteins E1 and E2. These studies revealed that both Fe2O3 and Fe3O4 interacted efficiently with the SARS-CoV-2 S1-RBD and to HCV glycoproteins, E1 and E2. Fe3O4 formed a more stable complex with S1-RBD whereas Fe2O3 favored HCV E1 and E2. These interactions of IONPs are expected to be assocd. with viral proteins conformational changes and hence, viral inactivation. Therefore, we recommend FDA-approved-IONPs to proceed for COVID-19 treatment clin. trials.
- 7Le Goas, M.; Saber, J.; Bolívar, S. G.; Rabanel, J.-M.; Awogni, J.-M.; Boffito, D. C.; Banquy, X. (In)Stability of Ligands at the Surface of Inorganic Nanoparticles: A Forgotten Question in Nanomedicine?. Nano Today 2022, 45, 101516, DOI: 10.1016/j.nantod.2022.101516Google Scholar7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhvFeiu7jL&md5=b756abce02d9bf830a77c27681167480Design inorganic nanoparticles based medicines with better clinical efficacy and translation abilityLe Goas, Marine; Saber, Justine; Bolivar, Sara Gonzalez; Rabanel, Jean-Michel; Awogni, Jean-Marc; Boffito, Daria C.; Banquy, XavierNano Today (2022), 45 (), 101516CODEN: NTAOCG; ISSN:1748-0132. (Elsevier Ltd.)A review. Multiple inorg. nanoparticles (NPs) are currently being developed for nanomedicine. Various core materials and shapes are explored, but they all display a common hybrid structure, with org. ligands on their surface. These ligands play a key role in the NP colloidal stability and surface properties, and therefore strongly impact the biol. fate of the NPs. However, ligands may be subject to reorganization, degrdn., desorption, and exchange, both during their shelf-life and upon exposure to a biol. environment. The question of ligand (in)stability at the surface of inorg. NPs has been little addressed in the literature. The goal of this review is to provide a portrait of this crit. phenomenon. We identify and review here the different mechanisms likely to promote ligand instability and discuss the resulting biol. fate of ligands. This review is aimed to provide a better understanding of these phenomena and to help researchers to design NP-based medicines with better clin. efficacy and translation ability.
- 8Wang, X.; Wang, X.; Bai, X.; Yan, L.; Liu, T.; Wang, M.; Song, Y.; Hu, G.; Gu, Z.; Miao, Q.; Chen, C. Nanoparticle Ligand Exchange and Its Effects at the Nanoparticle-Cell Membrane Interface. Nano Lett. 2019, 19 (1), 8– 18, DOI: 10.1021/acs.nanolett.8b02638Google Scholar8https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhvFWksbbN&md5=c175e516322e4c6a63de67fd362e4081Nanoparticle Ligand Exchange and Its Effects at the Nanoparticle-Cell Membrane InterfaceWang, Xinyi; Wang, Xiaofeng; Bai, Xuan; Yan, Liang; Liu, Tao; Wang, Mingzhe; Song, Youtao; Hu, Guoqing; Gu, Zhanjun; Miao, Qing; Chen, ChunyingNano Letters (2019), 19 (1), 8-18CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)The nanoparticle (nano)-cell membrane interface is one of the most important interactions detg. the fate of nanoparticles (NPs), which can stimulate a series of biol. events, allowing theranostic and other biomedical applications. So far, there remains a lack of knowledge about the mechanisms governing the nanoparticle-cell membrane interface, esp. the impact of ligand exchange, in which mols. on the nanosurface become replaced with components of the cell membrane, resulting in unique interfacial phenomena. Herein, we describe a family of gold nanoparticles (AuNPs) of the same core size (∼13 nm core), modified with 12 different kinds of surface ligands, and the effects of their exchangeable ligands on both nanoparticle-supported lipid bilayers (SLBs) and nanoparticle-natural cell membrane interfaces. The ligands are categorized according to their mol. wt., charge, and bonding modes (physisorption or chemisorption). Importantly, we found that, depending on the adsorption affinity and size of ligand mols., physisorbed ligands on the surface of NPs can be exchanged with lipid mols. At a ligand exchange-dominated interface, the AuNPs typically aggregated into an ordered monolayer in the lipid bilayers, subsequently affecting cell membrane integrity, NP uptake efficiency, and the NP endocytosis pathways. These findings advance our understanding of the underlying mechanisms of the biol. effects of nanoparticles from a new point of view and will aid in the design of novel, safe, and effective nanomaterials for biomedicine.
- 9Liu, M.; Ma, Y.; Wang, R. Y. Modifying Thermal Transport in Colloidal Nanocrystal Solids with Surface Chemistry. ACS Nano 2015, 9 (12), 12079– 12087, DOI: 10.1021/acsnano.5b05085Google Scholar9https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhsl2htLvI&md5=c17ac1fbde443b24b138c017bd2dacf3Modifying Thermal Transport in Colloidal Nanocrystal Solids with Surface ChemistryLiu, Minglu; Ma, Yuanyu; Wang, Robert Y.ACS Nano (2015), 9 (12), 12079-12087CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)The effect of surface chem. on thermal transport in colloidal nanocrystal (NC) solids has been studied. Using PbS NCs as a model system, the authors varied ligand binding group (thiol, amine, and at. halides), ligand length (ethanedithiol, butanedithiol, hexanedithiol, and octanedithiol), and NC diam. (3.3-8.2 nm). The expts. revealed several findings: (i) The ligand choice could vary the NC solid thermal cond. by up to a factor of 2.5; (ii) the ligand binding strength to the NC core did not significantly impact thermal cond.; (iii) reducing the ligand length could decrease the interparticle distance, which increases thermal cond.; (iv) increasing the NC diam. increased thermal cond.; and (v) the effect of surface chem. could exceed the effect of NC diam. and becomes more pronounced as NC diam. decreases. The thermal cond. of NC solids could be varied by an overall factor of 4, from ∼0.1-0.4 W/m-K. These findings were complemented with effective medium approxn. modeling and identify thermal transport in the ligand matrix as the rate-limiter for thermal transport. By combining these modeling results with our exptl. observations, the authors conclude that future efforts to increase thermal cond. in NC solids should focus on the ligand-ligand interface between neighboring NCs.
- 10Bian, H.; Li, J.; Chen, H.; Yuan, K.; Wen, X.; Li, Y.; Sun, Z.; Zheng, J. Molecular Conformations and Dynamics on Surfaces of Gold Nanoparticles Probed with Multiple-Mode Multiple-Dimensional Infrared Spectroscopy. J. Phys. Chem. C 2012, 116 (14), 7913– 7924, DOI: 10.1021/jp300970pGoogle Scholar10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XjvFKltL8%253D&md5=c4685c294a30ed5ebb1e37427354948bMolecular Conformations and Dynamics on Surfaces of Gold Nanoparticles Probed with Multiple-Mode Multiple-Dimensional Infrared SpectroscopyBian, Hongtao; Li, Jiebo; Chen, Hailong; Yuan, Kaijun; Wen, Xiewen; Li, Yaqin; Sun, Zhigang; Zheng, JunrongJournal of Physical Chemistry C (2012), 116 (14), 7913-7924CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Knowledge about mol. conformations and nuclear and electronic motions on surfaces of metal nanomaterials is crit. for many applications but extremely difficult to obtain. Valuable information of this sort can be detd. using multiple-mode multiple-dimensional vibrational spectroscopy. A model compd., 4-mercaptophenol, on the surface of 3.5 nm gold nanoparticles demonstrates the method. Its 3-dimensional mol. conformations and vibrational dynamics on the particle surfaces were detd. with the method. The exptl. results imply that on the particle surfaces, the ligand mols. cannot form energy-optimized hydrogen bonds because of the surface geometry constraint. The conclusion is supported with expts. on the ligand mols. in the cryst. phase and in a dil. soln. The authors' expts. also showed that the effect of the particle surface nonadiabatic electron/vibration coupling does not play a significant role in the vibrational relaxation of high-frequency modes (>1000 cm-1) ∼3 Å away from the surface. Simple theor. calcns. support this observation. The method holds promise as a general tool for the studies of mol. structures and dynamics on the surfaces of nanomaterials. The capability of resolving 3-dimensional mol. conformations on nanomaterials surfaces is expected to be helpful for understanding specific intermol. interactions and conformation-selective reactions (e.g., chirality selectivity) on the surfaces of these materials.
- 11Ionita, P.; Volkov, A.; Jeschke, G.; Chechik, V. Lateral Diffusion of Thiol Ligands on the Surface of Au Nanoparticles: An Electron Paramagnetic Resonance Study. Anal. Chem. 2008, 80 (1), 95– 106, DOI: 10.1021/ac071266sGoogle Scholar11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtlGis7vI&md5=a33081cc57b2c6b5b55c0848f979db88Lateral Diffusion of Thiol Ligands on the Surface of Au Nanoparticles: An Electron Paramagnetic Resonance StudyIonita, Petre; Volkov, Aleksei; Jeschke, Gunnar; Chechik, VictorAnalytical Chemistry (Washington, DC, United States) (2008), 80 (1), 95-106CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)The lateral mobility of the thiolate ligands on the surface of Au nanoparticles was probed by EPR spectroscopy. This was achieved by using bisnitroxide ligands, which contained a disulfide group (to ensure attachment to the Au surface) and a cleavable ester bridge connecting the two spin-labeled branches of the mol. Upon adsorption of these ligands on the surface of Au nanoparticles, the two spin-labeled branches were held next to each other by the ester bridge as evidenced by the spin-spin interactions. Cleavage of the bridge removed the link that kept the branches together. CW and pulsed EPR (DEER) expts. showed that the av. distance between the adjacent thiolate branches on the Au nanoparticle surface only marginally increased after cleaving the bridge and thermal treatment. This implies that the lateral diffusion of thiolate ligands on the nanoparticle surface is very slow at room temp. and takes hours even at elevated temps. (90°C). The changes in the distance distribution obsd. at high temp. are likely due to ligands hopping between the nanoparticles rather than diffusing on the particle surface.
- 12Dulle, M.; Jaber, S.; Rosenfeldt, S.; Radulescu, A.; Förster, S.; Mulvaney, P.; Karg, M. Plasmonic Gold-Poly(N-Isopropylacrylamide) Core-Shell Colloids with Homogeneous Density Profiles: A Small Angle Scattering Study. Phys. Chem. Chem. Phys. 2015, 17 (2), 1354– 1367, DOI: 10.1039/C4CP04816DGoogle ScholarThere is no corresponding record for this reference.
- 13Redel, E.; Walter, M.; Thomann, R.; Vollmer, C.; Hussein, L.; Scherer, H.; Krüger, M.; Janiak, C. Synthesis, Stabilization, Functionalization and, DFT Calculations of Gold Nanoparticles in Fluorous Phases (PTFE and Ionic Liquids). Chem.─Eur. J. 2009, 15 (39), 10047– 10059, DOI: 10.1002/chem.200900301Google ScholarThere is no corresponding record for this reference.
- 14Wu, Z.-P.; Shan, S.; Zang, S.-Q.; Zhong, C.-J. Dynamic Core-Shell and Alloy Structures of Multimetallic Nanomaterials and Their Catalytic Synergies. Acc. Chem. Res. 2020, 53 (12), 2913– 2924, DOI: 10.1021/acs.accounts.0c00564Google Scholar14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXit1yns7jI&md5=d45eea85fb31c7c4b82f998aefb2d1e3Dynamic Core-Shell and Alloy Structures of Multimetallic Nanomaterials and Their Catalytic SynergiesWu, Zhi-Peng; Shan, Shiyao; Zang, Shuang-Quan; Zhong, Chuan-JianAccounts of Chemical Research (2020), 53 (12), 2913-2924CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)Conspectus: Multimetallic nanomaterials contg. noble metals (NM) and non-noble 3d-transition metals (3d-TMs) exhibit unique catalytic properties as a result of the synergistic combination of NMs and 3d-TMs in the nanostructure. The exploration of such a synergy depends heavily on the understanding of the at.-scale structural details of NMs and 3d-TMs in the nanomaterials. This has attracted a great deal of recent interest in the field of catalysis science, esp. concerning the core-shell and alloy nanostructures. A rarely asked question of fundamental significance is how the core-shell and alloy structural arrangements of atoms in the multimetallic nanomaterials dynamically change under reaction conditions, including reaction temp., surface adsorbate, chem. environment, applied electrochem. potential, etc. The dynamic evolution of the core-shell/alloy structures under the reaction conditions plays a crucial role in the catalytic performance of the multimetallic nanocatalysts. This Account focuses on the dynamic structure characteristics for several different types of compn.-tunable alloy and core-shell nanomaterials, including phase-segregated, elemental-enriched, dynamically evolved, and structurally different core-shell structures. In addn. to outlining core-shell/alloy structure formation via processes such as seed-mediated growth, thermochem. calcination, adsorbate-induced evolution, chem. dealloying, underpotential deposition/galvanic displacement, etc., this Account will highlight the progress in understanding the dynamic core-shell/alloy structures under chem. or catalytic reaction conditions, which has become an important focal point of the research fronts in catalysis and electrocatalysis. The employment of advanced techniques, esp. in situ/operando synchrotron high-energy X-ray diffraction and pair distribution function analyses, has provided significant insights into the dynamic evolution processes of NM/3d-TM nanocatalysts under electrocatalytic or fuel cell operating conditions. Examples will highlight Pt- or Pd-based nanoparticles and nanowires alloyed with various 3d-TMs with a focus on their structural evolution under reaction conditions. While the dynamic process is complex, the ability to gain an insight into the evolution of core-shell and alloy structures under the catalytic reaction condition is essential for advancing the design of multimetallic nanocatalysts. This Account serves as a springboard from fundamental understanding of the core-shell and alloy structural dynamics to the various applications of nanostructured catalysts/electrocatalysts, esp. in the fronts of energy and environmental sustainability.
- 15Harris, R. A.; van der Walt, H.; Shumbula, P. M. Molecular Dynamics Study on Iron Oxide Nanoparticles Stabilised with Sebacic Acid and 1,10-Decanediol Surfactants. J. Mol. Struct. 2013, 1048, 18– 26, DOI: 10.1016/j.molstruc.2013.05.026Google Scholar15https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXht1Sktb%252FL&md5=1e6efa1c77c8b90cca69dfade6f32338Molecular dynamics study on iron oxide nanoparticles stabilized with Sebacic Acid and 1,10-Decanediol surfactantsHarris, R. A.; van der Walt, H.; Shumbula, P. M.Journal of Molecular Structure (2013), 1048 (), 18-26CODEN: JMOSB4; ISSN:0022-2860. (Elsevier B.V.)By using mol. dynamics in canonical ensemble (const. atom no., vol. and temp. (NVT)) the adsorption of sebacic acid (SA) and 1,10-decanediol (DD) onto the surfaces of an iron-oxide nanoparticle was simulated. The nanoparticle was built by taking into account the inverse spinel structure of a stoichiometric magnetite and the valence of the iron ions (Fe2+AFe2+BFe2+B where A and B stand for tetrahedral and octahedral sites, resp.). This study serves to det. theor. whether surfactants like SA or DD act as a better stabilizing agent for iron oxide nanoparticles of diams. ≥ 2.6 nm. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements on iron oxide nanoparticles stabilized with SA- and DD surfactants were obtained and compared to the simulated results. Unagglomerated nanoparticles with well-defined edges were obsd. during TEM for DD stabilized particles and a smaller particle size could be calcd. for these nanoparticles from XRD patterns. It is concluded that DD stabilizes an iron-oxide nanoparticle better than SA because of the difference in the no. of oxygen atoms on the resp. functional groups.
- 16Woehrle, G. H.; Brown, L. O.; Hutchison, J. E. Thiol-Functionalized, 1.5-Nm Gold Nanoparticles through Ligand Exchange Reactions: Scope and Mechanism of Ligand Exchange. J. Am. Chem. Soc. 2005, 127 (7), 2172– 2183, DOI: 10.1021/ja0457718Google Scholar16https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXmslWjsA%253D%253D&md5=22c2b3772b041df9a0e7b43ce580c9e5Thiol-Functionalized, 1.5-nm Gold Nanoparticles through Ligand Exchange Reactions: Scope and Mechanism of Ligand ExchangeWoehrle, Gerd H.; Brown, Leif O.; Hutchison, James E.Journal of the American Chemical Society (2005), 127 (7), 2172-2183CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Ligand exchange reactions of 1.5-nm triphenylphosphine-stabilized nanoparticles with ω-functionalized thiols provides a versatile approach to functionalized, 1.5-nm gold nanoparticles from a single precursor. We describe the broad scope of this method and the first mechanistic investigation of thiol-for-phosphine ligand exchanges. The method is convenient and practical and tolerates a surprisingly wide variety of technol. important functional groups while producing very stable nanoparticles that essentially preserve the small core size and size dispersity of the precursor particle. The mechanistic studies reveal a novel three-stage mechanism that can be used to control the extent of ligand exchange. During the first stage of the exchange, AuCl(PPh3) is liberated, followed by replacement of the remaining phosphine ligands as PPh3 (assisted by gold complexes in soln.). The final stage involves completion and reorganization of the thiol-based ligand shell.
- 17Price, W. S. Pulsed-Field Gradient Nuclear Magnetic Resonance as a Tool for Studying Translational Diffusion: Part 1. Basic Theory. Concepts Magn. Reson. 1997, 9 (5), 299– 336, DOI: 10.1002/(SICI)1099-0534(1997)9:5<299::AID-CMR2>3.0.CO;2-UGoogle Scholar17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2sXlvV2hu7Y%253D&md5=59f3537cc7bfbff4e02ad0b97e7721a8Pulsed-field gradient nuclear magnetic resonance as a tool for studying translational diffusion: Part 1. Basic theoryPrice, William S.Concepts in Magnetic Resonance (1997), 9 (5), 299-336CODEN: CMAEEM; ISSN:1043-7347. (Wiley)A review with 125 refs. Translational diffusion is the most fundamental form of transport in chem. and biochem. systems. Pulsed-field gradient NMR provides a convenient and noninvasive means for measuring translational motion. In this method the attenuation of the echo signal from a Hahn spin-echo pulse sequence contg. a magnetic field gradient pulse in each τ period was used to measure the displacement of the obsd. spins. The phys. basis of this method is considered. Starting from the Bloch equations contg. diffusion terms, the (anal.) equation linking the echo attenuation to the diffusion of the spin for the case of unrestricted isotropic diffusion is derived. When the motion of the spin occurs within a confined geometry or is anisotropic, such as in in vivo systems, the echo attenuation also yields information on the surrounding structure, but as the anal. approach becomes math. intractable, approx. or numerical means must be used to ext. the motional information. Two common approxns. are considered and their limitations are examd. Measurements in anisotropic systems are also considered.
- 18Polito, L.; Colombo, M.; Monti, D.; Melato, S.; Caneva, E.; Prosperi, D. Resolving the Structure of Ligands Bound to the Surface of Superparamagnetic Iron Oxide Nanoparticles by High-Resolution Magic-Angle Spinning NMR Spectroscopy. J. Am. Chem. Soc. 2008, 130 (38), 12712– 12724, DOI: 10.1021/ja802479nGoogle Scholar18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtVOqt7vJ&md5=a5f2153f3313279ca76f650f10999f56Resolving the Structure of Ligands Bound to the Surface of Superparamagnetic Iron Oxide Nanoparticles by High-Resolution Magic-Angle Spinning NMR SpectroscopyPolito, Laura; Colombo, Miriam; Monti, Diego; Melato, Sergio; Caneva, Enrico; Prosperi, DavideJournal of the American Chemical Society (2008), 130 (38), 12712-12724CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)A major challenge in magnetic nanoparticle synthesis and (bio)functionalization concerns the precise characterization of the nanoparticle surface ligands. We report the first anal. NMR investigation of org. ligands stably anchored on the surface of superparamagnetic nanoparticles (MNPs) through the development of a new exptl. application of high-resoln. magic-angle spinning (HRMAS). The conceptual advance here is that the HRMAS technique, already being used for MAS NMR anal. of gels and semisolid matrixes, enables the fine-structure-resolved characterization of even complex org. mols. bound to paramagnetic nanocrystals, such as nanosized iron oxides, by strongly decreasing the effects of paramagnetic disturbances. This method led to detail-rich, well-resolved 1H NMR spectra, often with highly structured first-order couplings, essential in the interpretation of the data. This HRMAS application was first evaluated and optimized using simple ligands widely used as surfactants in MNP synthesis and conjugation. Next, the methodol. was assessed through the structure detn. of complex mol. architectures, such as those involved in MNP3 and MNP4. The comparison with conventional probes evidences that HRMAS makes it possible to work with considerably higher concns., thus avoiding the loss of structural information. Consistent 2D homonuclear 1H-1H and 1H-13C heteronuclear single-quantum coherence correlation spectra were also obtained, providing reliable elements on proton signal assignments and carbon characterization and opening the way to 13C NMR detn. Notably, combining the exptl. evidence from HRMAS 1H NMR and diffusion-ordered spectroscopy performed on the hybrid nanoparticle dispersion confirmed that the ligands were tightly bound to the particle surface when they were dispersed in a ligand-free solvent, while they rapidly exchanged when an excess of free ligand was present in soln. In addn. to HRMAS NMR, matrix-assisted laser desorption ionization time-of-flight MS anal. of modified MNPs proved very valuable in ligand mass identification, thus giving a sound support to NMR characterization achievements.
- 19Hempelmann, R. Quasielastic Neutron Scattering and Solid State Diffusion; Oxford University Press: Oxford, 2000; . DOI: 10.1093/acprof:oso/9780198517436.001.0001 .Google ScholarThere is no corresponding record for this reference.
- 20Sears, V. F. Neutron Scattering Lengths and Cross Sections. Neutron News 1992, 3 (3), 26– 37, DOI: 10.1080/10448639208218770Google ScholarThere is no corresponding record for this reference.
- 21Marry, V.; Dubois, E.; Malikova, N.; Breu, J.; Haussler, W. Anisotropy of Water Dynamics in Clays: Insights from Molecular Simulations for Experimental QENS Analysis. J. Phys. Chem. C 2013, 117 (29), 15106– 15115, DOI: 10.1021/jp403501hGoogle Scholar21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtValsb3I&md5=a0c48b69ea675dbe2a49254000d146a9Anisotropy of Water Dynamics in Clays: Insights from Molecular Simulations for Experimental QENS AnalysisMarry, V.; Dubois, E.; Malikova, N.; Breu, J.; Haussler, W.Journal of Physical Chemistry C (2013), 117 (29), 15106-15115CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)We measure H2O dynamics in a well-defined synthetic hectorite clay by the neutron spin echo technique, in the temp. range from 240 to 347 K. The interlayer spaces of this anisotropic material contain two layers of confined water, corresponding to the so-called bihydrated state. We analyze the exptl. data in light of parallel mol. dynamics simulations. Simulations demonstrate that H2O diffusion in the direction perpendicular to the clay layers is not negligible and has to be taken into account in the exptl. data anal. A diffusive model with only two fitting parameters D.perp. and D‖ is well adapted for such anal. A clear phys. meaning for the two fitting parameters exists, in view of the geometry of the system. Exptl., the diffusion coeffs. parallel to the clay layers D‖ were estd. to be slowed down by a factor of 5 compared to bulk water. Further, the activation energy of the diffusion process is higher than in bulk water esp. toward the lower temps. within the range studied (20.3 kJ/mol above 300 K increasing to 28.4 kJ/mol below 300 K). Simulations suggest that this is connected to the presence of the cations (1 cation per every 8 water mols.) rather than to the formation of hydrogen bonds between H2O mols. and the clay layers. However, improvements of microscopic force fields are necessary to achieve a full quant. interpretation of the exptl. water diffusion coeffs. We suggest the importance of polarizability in such endeavors.
- 22Paradossi, G.; Cavalieri, F.; Chiessi, E.; Telling, M. T. F. Supercooled Water in PVA Matrixes: I. An Incoherent Quasi-Elastic Neutron Scattering (QENS) Study. J. Phys. Chem. B 2003, 107 (33), 8363– 8371, DOI: 10.1021/jp034542pGoogle Scholar22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXlt1ygsLg%253D&md5=2479eac6816c5e5c8a7c9dcb7147b76aSupercooled Water in PVA Matrixes: I. An Incoherent Quasi-Elastic Neutron Scattering (QENS) StudyParadossi, Gaio; Cavalieri, Francesca; Chiessi, Ester; Telling, Mark T. F.Journal of Physical Chemistry B (2003), 107 (33), 8363-8371CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)The incoherent quasi-elastic neutron scattering study of poly(vinyl alc.) based hydrogels was carried out to elucidate the dynamic state of water caged in polymeric matrixes with different degree of crosslinking and nature of the crosslinking agent. This investigation focuses on the detn. of the relationship occurring between the diffusional parameters of water and the polymer network architecture. Analyzing the broadening factor of the dynamic structure factor, a marked supercooling of water was detected in all the matrixes under consideration. In all cases, the activation energies were about 4 kcal/mol indicating a hydrogen bond regime governing the matrix-solvent interaction. In some favorable cases, an insight on the polymer dynamics was also possible. The q-dependence of the broadening factor of polymer relaxation component revealed a behavior compatible with a bound random jump dynamics and concerning segmental motions of the chain coupled with the interaction with water.
- 23Abe, H.; Takekiyo, T.; Yoshimura, Y.; Shimizu, A. Static and Dynamic Properties of Nano-Confined Water in Room-Temperature Ionic Liquids. J. Mol. Liq. 2019, 290, 111216, DOI: 10.1016/j.molliq.2019.111216Google Scholar23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtlaltbrI&md5=f0f5581603272e0ecf28ca0f2e74bfaaStatic and dynamic properties of nano-confined water in room-temperature ionic liquidsAbe, Hiroshi; Takekiyo, Takahiro; Yoshimura, Yukihiro; Shimizu, AkioJournal of Molecular Liquids (2019), 290 (), 111216CODEN: JMLIDT; ISSN:0167-7322. (Elsevier B.V.)A review. Nano-confined water ("water pocket") was spontaneously formed in room-temp. ionic liq. (RTIL). The static structure of the self-dispersed "water pocket" was detd. by a complementary use of small-angle X-ray scattering and small-angle neutron scattering. The size of the "water pocket" is tuned by the water concn. and temp. The "water pocket" suppressed the crystns. both of the RTIL and water at low temp. The solidifications in the intermediate concn. region were quite sensitive to the cooling rate, and non-equil. degree in the mixt. was enhanced by the "water pocket". Hydrogen bonding of water mols. in the "water pocket" was weakened by the nano-confinement. Slow dynamics of the "water pocket" in the RTIL was clarified by quasielastic neutron scattering. The loosely packed and size-tunable "water pocket" is utilized for next generation nano-heterogeneity engineering.
- 24Mamontov, E.; Wesolowski, D. J.; Vlcek, L.; Cummings, P. T.; Rosenqvist, J.; Wang, W.; Cole, D. R. Dynamics of Hydration Water on Rutile Studied by Backscattering Neutron Spectroscopy and Molecular Dynamics Simulation. J. Phys. Chem. C 2008, 112 (32), 12334– 12341, DOI: 10.1021/jp711965xGoogle Scholar24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXosFKnurg%253D&md5=4ae091ede7d055d800708f25ccc7cd7dDynamics of Hydration Water on Rutile Studied by Backscattering Neutron Spectroscopy and Molecular Dynamics SimulationMamontov, E.; Wesolowski, D. J.; Vlcek, L.; Cummings, P. T.; Rosenqvist, J.; Wang, W.; Cole, D. R.Journal of Physical Chemistry C (2008), 112 (32), 12334-12341CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)The high energy resoln., coupled with the wide dynamic range, of the new backscattering spectrometer (BASIS) at the Spallation Neutron Source, Oak Ridge National Lab., has made it possible to investigate the diffusion dynamics of hydration water on the surface of rutile (TiO2) nanopowder down to a temp. of 195 K. The dynamics measured on the BASIS on the time scale of tens of picoseconds to more than a nanosecond can be attributed to the mobility of the outer hydration water layers. The data obtained on the BASIS and in a previous study using the backscattering and disk-chopper spectrometers at the NIST Center for Neutron Research are coupled with mol. dynamics simulations extended to 50 ns. The results suggest that the scattering expts. probe several types of mol. motion in the surface layers, namely a very fast component that involves dynamics of water mols. with unsatd. hydrogen bonds, a somewhat slower component due to localized motions of all water mols., and a much slower component related to the translational jumps of the fully hydrogen-bonded water mols. The temp. dependence of the relaxation times assocd. with the localized dynamics remains Arrhenius down to at least 195 K, whereas the slow translational component shows non-Arrhenius behavior above about 205 K. Thus, an Arrhenius-type behavior of the faster localized dynamic component extends below the temp. of the dynamic transition in the slow translational component. We suggest that the qual. difference in the character of the temp. dependence between these slow and fast components may be due to the fact that the latter involves motions that require breaking fewer hydrogen bonds.
- 25Jansen, M.; Juranyi, F.; Yarema, O.; Seydel, T.; Wood, V. Ligand Dynamics in Nanocrystal Solids Studied with Quasi-Elastic Neutron Scattering. ACS Nano 2021, 15 (12), 20517– 20526, DOI: 10.1021/acsnano.1c09073Google ScholarThere is no corresponding record for this reference.
- 26Seydel, T.; Koza, M. M.; Matsarskaia, O.; André, A.; Maiti, S.; Weber, M.; Schweins, R.; Prévost, S.; Schreiber, F.; Scheele, M. A Neutron Scattering Perspective on the Structure, Softness and Dynamics of the Ligand Shell of PbS Nanocrystals in Solution. Chem. Sci. 2020, 11 (33), 8875– 8884, DOI: 10.1039/D0SC02636KGoogle Scholar26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsFSlsr7J&md5=abeabbc0a8dd290b2220a9ac3d69a302A neutron scattering perspective on the structure, softness and dynamics of the ligand shell of PbS nanocrystals in solutionSeydel, Tilo; Koza, Michael Marek; Matsarskaia, Olga; Andre, Alexander; Maiti, Santanu; Weber, Michelle; Schweins, Ralf; Prevost, Sylvain; Schreiber, Frank; Scheele, MarcusChemical Science (2020), 11 (33), 8875-8884CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)Small-angle neutron and X-ray scattering, neutron backscattering and neutron time-of-flight spectroscopy are applied to reveal the structure of the ligand shell, the temp.-dependent diffusion properties and the phonon spectrum of PbS nanocrystals functionalized with oleic acid in deuterated hexane. The nanocrystals decorated with oleic acid as well as the desorbed ligand mols. exhibit simple Brownian diffusion with a Stokes-Einstein temp.-dependence and inhibited freezing. Ligand mols. desorbed from the surface show strong spatial confinement. The phonon spectrum of oleic acid adsorbed to the nanocrystal surface exhibits hybrid modes with a predominant Pb-character. Low-energy surface modes of the NCs are prominent and indicate a large mech. softness in soln. This work provides comprehensive insights into the ligand-particle interaction of colloidal nanocrystals in soln. and highlights its effect on the diffusion and vibrational properties as well as their mech. softness.
- 27Sharma, A.; Kruteva, M.; Zamponi, M.; Ehlert, S.; Richter, D.; Förster, S. Quasielastic Neutron Scattering Reveals the Temperature Dependent Rotational Dynamics of Densely Grafted Oleic Acid. J. Chem. Phys. 2022, 156 (16), 164908, DOI: 10.1063/5.0089874Google ScholarThere is no corresponding record for this reference.
- 28Sharma, A.; Kruteva, M.; Zamponi, M.; Ehlert, S.; Richter, D.; Förster, S. Influence of Molecular Weight on the Distribution of Segmental Relaxation in Polymer Grafted Nanoparticles. Phys. Rev. Mater. 2022, 6 (1), L012601, DOI: 10.1103/PhysRevMaterials.6.L012601Google Scholar28https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xjt1yru7s%253D&md5=bd60e43bfe29bc86b5690fcbf3540697Influence of molecular weight on the distribution of segmental relaxation in polymer grafted nanoparticlesSharma, Aakash; Kruteva, Margarita; Zamponi, Michaela; Ehlert, Sascha; Richter, Dieter; Foerster, StephanPhysical Review Materials (2022), 6 (1), L012601CODEN: PRMHBS; ISSN:2475-9953. (American Physical Society)The segmental dynamics of one-component nanocomposites (OCNC) is significantly influenced by the mol. wt. (Mw) of the grafted polymer. Neutron backscattering shows that compared to the neat polymer the OCNCs exhibit a shift from slower segmental dynamics at low Mw to faster dynamics at high Mw. We model the local relaxation as distribution of exponential diffusers. This approach reveals the presence of fast and slow segments in both OCNCs. However, their fractional contribution varies with Mw leading to different av. relaxation times. Our results present important insights into the origin of segmental mobility in OCNC and address the inconsistencies in different literature reports.
- 29Jhalaria, M.; Buenning, E.; Huang, Y.; Tyagi, M.; Zorn, R.; Zamponi, M.; García-Sakai, V.; Jestin, J.; Benicewicz, B. C.; Kumar, S. K. Accelerated Local Dynamics in Matrix-Free Polymer Grafted Nanoparticles. Phys. Rev. Lett. 2019, 123, 158003, DOI: 10.1103/PhysRevLett.123.158003Google Scholar29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXit1ensrjK&md5=160100c0cf6458116ec5c7f56f72dfb6Accelerated Local Dynamics in Matrix-Free Polymer Grafted NanoparticlesJhalaria, Mayank; Buenning, Eileen; Huang, Yucheng; Tyagi, Madhusudan; Zorn, Reiner; Zamponi, Michaela; Garcia-Sakai, Victoria; Jestin, Jacques; Benicewicz, Brian C.; Kumar, Sanat K.Physical Review Letters (2019), 123 (15), 158003CODEN: PRLTAO; ISSN:1079-7114. (American Physical Society)The tracer diffusion coeff. of six different permanent gases in polymer-grafted nanoparticle (GNP) membranes, i.e., neat GNP constructs with no solvent, show a max. as a function of the grafted chain length at fixed grafting d. This trend is reproduced for two different NP sizes and three different polymer chemistries. We postulate that nonmonotonic changes in local, segmental friction as a function of graft chain length (at fixed grafting d.) must underpin these effects, and use quasielastic neutron scattering to probe the self-motions of polymer chains at the relevant segmental scale (i.e., sampling local friction or viscosity). These data, when interpreted with a jump diffusion model, show that, in addn. to the speeding-up in local chain dynamics, the elementary distance over which segments hop is strongly dependent on graft chain length. We therefore conclude that transport modifications in these GNP layers, which are underpinned by a structural transition from a concd. brush to semidilute polymer brush, are a consequence of both spatial and temporal changes, both of which are likely driven by the lower polymer densities of the GNPs relative to the neat polymer.
- 30Pradeep, T.; Mitra, S.; Nair, A. S.; Mukhopadhyay, R. Dynamics of Alkyl Chains in Monolayer-Protected Au and Ag Clusters and Silver Thiolates: A Comprehensive Quasielastic Neutron Scattering Investigation. J. Phys. Chem. B 2004, 108 (22), 7012– 7020, DOI: 10.1021/jp0369950Google Scholar30https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXjs1SjsLY%253D&md5=2e5fb16af1b076c70c056173b1f5f909Dynamics of Alkyl Chains in Monolayer-Protected Au and Ag Clusters and Silver Thiolates: A Comprehensive Quasielastic Neutron Scattering InvestigationPradeep, T.; Mitra, S.; Nair, A. Sreekumaran; Mukhopadhyay, R.Journal of Physical Chemistry B (2004), 108 (22), 7012-7020CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)Temp.-dependent dynamics of monolayer-protected Au and Ag nanoclusters and silver thiolates have been investigated with quasielastic neutron scattering. The simplest motion in these systems is the uniaxial rotation of the chain, which evolves slowly with temp. While longer chain monolayers (above C8) on Au clusters are rotationally frozen at room temp., dynamic freedom exists in lower chain lengths. In the superlattice solids of Ag clusters, the dynamics evolve slowly, and at superlattice melting, all the chains are dynamic. The data are consistent with a structure in which the monolayers form bundles on the planes of metal clusters and such bundles interdigitate, forming the cluster assemblies. In thiolates, the dynamics is distinctly different in long- and short-chain systems. It arises abruptly at the melting temp. in C12 but a bit sluggishly in C18, whereas in C6 and C8, it evolves with temp. The data are correlated with temp.-dependent IR spectroscopy, which preserves some of the progression bands even after the bulk melting temp., but loses them completely above 498 K, suggesting a possible partially ordered phase in this temp. window. Our studies have established the fact that (a) no rotational freedom exists in several of the alkyl chain monolayers on metal cluster solids at room temp., (b) simple uniaxial rotation explains the dynamics of these systems, (c) the dynamics evolves slowly, and (d) such motions arise abruptly in long-chain layered thiolates which are similar to planar thiolates. We find that longer chains can possess conformational defects at higher temps., which slow the rotational dynamics.
- 31Bailey, E. J.; Winey, K. I. Dynamics of Polymer Segments, Polymer Chains, and Nanoparticles in Polymer Nanocomposite Melts: A Review. Prog. Polym. Sci. 2020, 105, 101242, DOI: 10.1016/j.progpolymsci.2020.101242Google Scholar31https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXps1yjsro%253D&md5=60f2d9f57cac719bb448aef2d4e85036Dynamics of polymer segments, polymer chains, and nanoparticles in polymer nanocomposite melts: A reviewBailey, Eric J.; Winey, Karen I.Progress in Polymer Science (2020), 105 (), 101242CODEN: PRPSB8; ISSN:0079-6700. (Elsevier Ltd.)A review. The addn. of nanoparticles to a polymer matrix, forming a polymer nanocomposite (PNC), is known to alter the microscopic dynamic processes of both species which leads to unique macroscopic material properties of the PNC. Because the NPs and polymers have overlapping characteristic length, time, and energy scales, the interactions within these materials are complex and the dynamics are interrelated. In this review, we present an overview of exptl., simulation, and theor. results that probe multi-scale polymer and nanoparticle dynamics in polymer nanocomposites and navigate the dense parameter space presented by these multicomponent systems. Although a variety of PNC systems are mentioned, we focus this discussion on linear thermoplastics filled with hard spherical or cylindrical NPs in the melt state. We begin by introducing PNCs, the dynamic processes within them, and the importance of dynamics for properties and processing. At the smallest length and time scales, we discuss segmental dynamics in PNCs, including the role of polymer attributes, NP attributes, and NP-polymer interactions. Then, we present measurements of collective motions and intermediate (Rouse) dynamics in various PNC materials. At longer length and time scales, we discuss polymer center-of-mass diffusion in PNCs with either spherical or anisotropic NPs. Finally, we note some of the remaining challenges in probing dynamics in PNC materials and fundamentally studying PNCs more generally.
- 32Shrestha, S.; Jiang, P.; Sousa, M. H.; Morais, P. C.; Mao, Z.; Gao, C. Citrate-Capped Iron Oxide Nanoparticles Impair the Osteogenic Differentiation Potential of Rat Mesenchymal Stem Cells. J. Mater. Chem. B 2016, 4 (2), 245– 256, DOI: 10.1039/C5TB02007GGoogle ScholarThere is no corresponding record for this reference.
- 33Milek, T.; Zahn, D. A Surfactants Walk to Work: Modes of Action of Citrate Controlling (10–10) and (000–1) Zinc Oxide Surface Growth from Solution. Z. Anorg. Allg. Chem. 2016, 642 (16), 902– 905, DOI: 10.1002/zaac.201600147Google ScholarThere is no corresponding record for this reference.
- 34Klausen, S. N.; Lefmann, K.; Lindgård, P.-A.; Clausen, K. N.; Hansen, M. F.; Bødker, F.; Mørup, S.; Telling, M. An Inelastic Neutron Scattering Study of Hematite Nanoparticles. J. Magn. Magn. Mater. 2003, 266 (1–2), 68– 78, DOI: 10.1016/S0304-8853(03)00457-8Google ScholarThere is no corresponding record for this reference.
- 35Gazeau, F.; Dubois, E.; Hennion, M.; Perzynski, R.; Raikher, Y. Quasi-Elastic Neutron Scattering on γ-Fe 2 O 3 Nanoparticles. Europhys. Lett. 1997, 40 (5), 575– 580, DOI: 10.1209/epl/i1997-00507-2Google ScholarThere is no corresponding record for this reference.
- 36Eckardt, M.; Thomä, S. L. J.; Dulle, M.; Hörner, G.; Weber, B.; Förster, S.; Zobel, M. Long-Term Colloidally Stable Aqueous Dispersions of ≤ 5 Nm Spinel Ferrite Nanoparticles. ChemistryOpen 2020, 9 (11), 1214– 1220, DOI: 10.1002/open.202000313Google ScholarThere is no corresponding record for this reference.
- 37Thomä, S. L. J.; Krauss, S. W.; Eckardt, M.; Chater, P.; Zobel, M. Atomic Insight into Hydration Shells around Facetted Nanoparticles. Nat. Commun. 2019, 10 (1), 995, DOI: 10.1038/s41467-019-09007-1Google Scholar37https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB3cfpsFSksw%253D%253D&md5=ee580d9f332e3f6b30c8c50c030b1cf7Atomic insight into hydration shells around facetted nanoparticlesThoma Sabrina L J; Krauss Sebastian W; Eckardt Mirco; Zobel Mirijam; Chater PhilNature communications (2019), 10 (1), 995 ISSN:.Nanoparticles in solution interact with their surroundings via hydration shells. Although the structure of these shells is used to explain nanoscopic properties, experimental structural insight is still missing. Here we show how to access the hydration shell structures around colloidal nanoparticles in scattering experiments. For this, we synthesize variably functionalized magnetic iron oxide nanoparticle dispersions. Irrespective of the capping agent, we identify three distinct interatomic distances within 2.5 ÅA from the particle surface which belong to dissociatively and molecularly adsorbed water molecules, based on theoretical predictions. A weaker restructured hydration shell extends up to 15 ÅA. Our results show that the crystal structure dictates the hydration shell structure. Surprisingly, facets of 7 and 15 nm particles behave like planar surfaces. These findings bridge the large gap between spectroscopic studies on hydrogen bond networks and theoretical advances in solvation science.
- 38Zobel, M.; Appel, M. Water Dynamics on Iron Oxide Nanoparticles; Institut Laue-Langevin Database, 2020. DOI: 10.5291/ILL-DATA.EASY-636 .Google ScholarThere is no corresponding record for this reference.
- 39Zobel, M.; Appel, M.; Feghelm, A.; Magerl, A.; Thomae, S. Diffusion Dynamics of Water and Citrate Molecules on the Surface of Iron Oxide Nanoparticles; Institut Laue-Langevin Database, 2021. DOI: 10.5291/ILL-DATA.9-12-648 .Google ScholarThere is no corresponding record for this reference.
- 40Appel, M.; Frick, B.; Magerl, A. First Results with the Neutron Backscattering and TOF Spectrometer Option BATS on IN16B. Phys. B: Condens. Matter 2019, 562, 6– 8, DOI: 10.1016/j.physb.2018.11.062Google Scholar40https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXkvVCht78%253D&md5=15b0809533464f7319ae32db703058b1First results with the neutron backscattering and TOF spectrometer option BATS on IN16BAppel, Markus; Frick, Bernhard; Magerl, AndreasPhysica B: Condensed Matter (Amsterdam, Netherlands) (2019), 562 (), 6-8CODEN: PHYBE3; ISSN:0921-4526. (Elsevier B.V.)We report on the status of the ongoing upgrade of the neutron backscattering spectrometer IN16B with the new BATS option, which enables operation of the instrument in inverted Time-of-Flight mode. First commissioning results are available, confirming the expectations and demonstrating its capabilities. Using Si 111 analyzers, BATS allows to record neutron spectra with variable energy resoln. down to 1.5 μeV with momentum transfers up to 1.9 Å-1, reaching energy transfers beyond -600 μeV and achieving a signal to noise ratio above 104.
- 41Zobel, M.; Appel, M.; Magerl, A.; Thomae, S. Diffusion in the Liquid Interface Region of IONPs; Institut Laue-Langevin Database, 2021. DOI: 10.5291/ILL-DATA.INTER-528 .Google ScholarThere is no corresponding record for this reference.
- 42Arnold, O.; Bilheux, J. C.; Borreguero, J. M.; Buts, A.; Campbell, S. I.; Chapon, L.; Doucet, M.; Draper, N.; Ferraz Leal, R.; Gigg, M. A. Mantid─Data Analysis and Visualization Package for Neutron Scattering and SR Experiments. Nucl. Instrum. Methods Phys. Res., Sect. A 2014, 764, 156– 166, DOI: 10.1016/j.nima.2014.07.029Google Scholar42https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtlGntrfL&md5=9a34bb9e366fca0e39091a5c4016ccd7Mantid-Data analysis and visualization package for neutron scattering and μ SR experimentsArnold, O.; Bilheux, J. C.; Borreguero, J. M.; Buts, A.; Campbell, S. I.; Chapon, L.; Doucet, M.; Draper, N.; Ferraz Leal, R.; Gigg, M. A.; Lynch, V. E.; Markvardsen, A.; Mikkelson, D. J.; Mikkelson, R. L.; Miller, R.; Palmen, K.; Parker, P.; Passos, G.; Perring, T. G.; Peterson, P. F.; Ren, S.; Reuter, M. A.; Savici, A. T.; Taylor, J. W.; Taylor, R. J.; Tolchenov, R.; Zhou, W.; Zikovsky, J.Nuclear Instruments & Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment (2014), 764 (), 156-166CODEN: NIMAER; ISSN:0168-9002. (Elsevier B.V.)The Mantid framework is a software soln. developed for the anal. and visualization of neutron scattering and muon spin measurements. The framework is jointly developed by software engineers and scientists at the ISIS Neutron and Muon Facility and the Oak Ridge National Lab. The objectives, functionality and novel design aspects of Mantid are described.
- 43Studer, A. J.; Hagen, M. E.; Noakes, T. J. Wombat: The High-Intensity Powder Diffractometer at the OPAL Reactor. Phys. B: Condens. Matter 2006, 385–386, 1013– 1015, DOI: 10.1016/j.physb.2006.05.323Google Scholar43https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28Xht1CitLvE&md5=f0b3d824628269df296550f430abeff0Wombat: The high-intensity powder diffractometer at the OPAL reactorStuder, Andrew J.; Hagen, Mark E.; Noakes, Terrence J.Physica B: Condensed Matter (Amsterdam, Netherlands) (2006), 385-386 (Pt. 2), 1013-1015CODEN: PHYBE3; ISSN:0921-4526. (Elsevier B.V.)The Wombat powder diffractometer will be located on the TG1 thermal guide at the OPAL reactor. A variable vertically focusing monochromator will provide a flux of up to ≈108 ns-1 cm-2 at the sample position. A compact curved 2-dimensional position sensitive detector will allow simultaneous acquisition of 120° in 2θ, with ≈106 s-1 count rate capability and time resoln. down to the microsecond level. Wombat is designed for expts. requiring rapid real time acquisition (time-resolved environmental or kinetics expts.) or very good signal to noise (expts. with difficult sample environments or small sample vols.).
- 44Toby, B. H.; Von Dreele, R. B. GSAS-II: the genesis of a modern open-source all purpose crystallography software package. J. Appl. Crystallogr. 2013, 46 (2), 544– 549, DOI: 10.1107/S0021889813003531Google Scholar44https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjvFWnu7c%253D&md5=48a7dcdb1d1f10d6f9d7fe3e746d58fdGSAS-II: the genesis of a modern open-source all purpose crystallography software packageToby, Brian H.; Von Dreele, Robert B.Journal of Applied Crystallography (2013), 46 (2), 544-549CODEN: JACGAR; ISSN:0021-8898. (International Union of Crystallography)The newly developed GSAS-II software is a general purpose package for data redn., structure soln. and structure refinement that can be used with both single-crystal and powder diffraction data from both neutron and x-ray sources, including lab. and synchrotron sources, collected on both two- and 1-dimensional detectors. It is intended that GSAS-II will eventually replace both the GSAS and the EXPGUI packages, as well as many other utilities. GSAS-II is open source and is written largely in object-oriented Python but offers speeds comparable to compiled code because of its reliance on the Python NumPy and SciPy packages for computation. It runs on all common computer platforms and offers highly integrated graphics, both for a user interface and for interpretation of parameters. The package can be applied to all stages of crystallog. anal. for const.-wavelength x-ray and neutron data. Plans for considerable addnl. development are discussed.
- 45Perez-Mato, J. M.; Gallego, S. V.; Tasci, E. S.; Elcoro, L.; de la Flor, G.; Aroyo, M. I. Symmetry-Based Computational Tools for Magnetic Crystallography. Annu. Rev. Mater. Res. 2015, 45 (1), 217– 248, DOI: 10.1146/annurev-matsci-070214-021008Google Scholar45https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFWqurvM&md5=210c550fb8617fc74460b8e891df6a5eSymmetry-Based Computational Tools for Magnetic CrystallographyPerez-Mato, J. M.; Gallego, S. V.; Tasci, E. S.; Elcoro, L.; de la Flor, G.; Aroyo, M. I.Annual Review of Materials Research (2015), 45 (), 217-248CODEN: ARMRCU; ISSN:1531-7331. (Annual Reviews)In recent years, two important advances have opened new doors for the characterization and detn. of magnetic structures. Firstly, researchers have produced computer-readable listings of the magnetic or Shubnikov space groups. Secondly, they have extended and applied the superspace formalism, which is presently the std. approach for the description of nonmagnetic incommensurate structures and their symmetry, to magnetic structures. These breakthroughs have been the basis for the subsequent development of a series of computer tools that allow a more efficient and comprehensive application of magnetic symmetry, both commensurate and incommensurate. Here we briefly review the capabilities of these computation instruments and present the fundamental concepts on which they are based, providing various examples. We show how these tools facilitate the use of symmetry arguments expressed as either a magnetic space group or a magnetic superspace group and allow the exploration of the possible magnetic orderings assocd. with one or more propagation vectors in a form that complements and goes beyond the traditional representation method. Special focus is placed on the programs available online at the Bilbao Crystallog. Server (http://www.cryst.ehu.es).
- 46Sabrina, L. J. Thomä; Mirijam Zobel. Ethanol-Water Motifs - a Re-Interpretation of the Double-Difference Pair Distribution Functions of Aqueous Iron Oxide Nanoparticle Dispersions. J. Chem. Phys. 2024, 158 (22), 224704, DOI: 10.1063/5.0147659Google ScholarThere is no corresponding record for this reference.
- 47Petkov, V.; Cozzoli, P. D.; Buonsanti, R.; Cingolani, R.; Ren, Y. Size, Shape, and Internal Atomic Ordering of Nanocrystals by Atomic Pair Distribution Functions: A Comparative Study of γ-Fe2O3 Nanosized Spheres and Tetrapods. J. Am. Chem. Soc. 2009, 131 (40), 14264– 14266, DOI: 10.1021/ja9067589Google Scholar47https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhtFKkt7jP&md5=34e2cef6d9ec060ed3ad22638d7882d2Size, Shape, and Internal Atomic Ordering of Nanocrystals by Atomic Pair Distribution Functions: A Comparative Study of γ-Fe2O3 Nanosized Spheres and TetrapodsPetkov, Valeri; Cozzoli, P. Davide; Buonsanti, Raffaella; Cingolani, Roberto; Ren, YangJournal of the American Chemical Society (2009), 131 (40), 14264-14266CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Due to their limited length of structural coherence nanocryst. materials show very diffuse powder x-ray diffraction patterns that are difficult to interpret unambiguously. A combination of high-energy x-ray powder diffraction and at. pair distribution function anal. can be used to both assess the geometry (i.e., size and shape) and det. the internal at. ordering of nanocryst. materials in a straightforward way. As an example cubic γ-Fe2O3 nanosized crystals shaped as spheres and tetrapods are considered.
- 48Shmakov, A. N.; Kryukova, G. N.; Tsybulya, S. V.; Chuvilin, A. L.; Solovyeva, L. P. Vacancy Ordering in γ-Fe2O3: Synchrotron X-Ray Powder Diffraction and High-Resolution Electron Microscopy Studies. J. Appl. Crystallogr. 1995, 28 (2), 141– 145, DOI: 10.1107/S0021889894010113Google ScholarThere is no corresponding record for this reference.
- 49Girardet, T.; Venturini, P.; Martinez, H.; Dupin, J.-C.; Cleymand, F.; Fleutot, S. Spinel Magnetic Iron Oxide Nanoparticles: Properties, Synthesis and Washing Methods. Appl. Sci. 2022, 12 (16), 8127, DOI: 10.3390/app12168127Google ScholarThere is no corresponding record for this reference.
- 50Bixner, O.; Lassenberger, A.; Baurecht, D.; Reimhult, E. Complete Exchange of the Hydrophobic Dispersant Shell on Monodisperse Superparamagnetic Iron Oxide Nanoparticles. Langmuir 2015, 31 (33), 9198– 9204, DOI: 10.1021/acs.langmuir.5b01833Google Scholar50https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXht1Knu7fK&md5=f1e29e2ad1a731259f6cf1eaa572a68fComplete Exchange of the Hydrophobic Dispersant Shell on Monodisperse Superparamagnetic Iron Oxide NanoparticlesBixner, Oliver; Lassenberger, Andrea; Baurecht, Dieter; Reimhult, ErikLangmuir (2015), 31 (33), 9198-9204CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)High-temp. synthesized monodisperse superparamagnetic iron oxide nanoparticles are obtained with a strongly bound ligand shell of oleic acid and its decompn. products. Most applications require a stable presentation of a defined surface chem.; therefore, the native shell has to be completely exchanged for dispersants with irreversible affinity to the nanoparticle surface. Attenuated total reflectance IR spectra and thermogravimetric anal./differential scanning calorimetry were used to evaluate the limitations of commonly used approaches. A mechanism and multiple exchange scheme that attains the goal of complete and irreversible ligand replacement on monodisperse nanoparticles of various sizes is presented. The obtained hydrophobic nanoparticles are ideally suited for magnetically controlled drug delivery and membrane applications and for the investigation of fundamental interfacial properties of ultra small core-shell architectures.
- 51Hill, A. H.; Jacobsen, H.; Stewart, J. R.; Jiao, F.; Jensen, N. P.; Holm, S. L.; Mutka, H.; Seydel, T.; Harrison, A.; Lefmann, K. Magnetic Properties of Nano-Scale Hematite, α-Fe2O3, Studied by Time-of-Flight Inelastic Neutron Spectroscopy. J. Chem. Phys. 2014, 140 (4), 044709, DOI: 10.1063/1.4862235Google ScholarThere is no corresponding record for this reference.
- 52Brown, W. F. Thermal Fluctuations of a Single-Domain Particle. Phys. Rev. 1963, 130 (5), 1677– 1686, DOI: 10.1103/PhysRev.130.1677Google ScholarThere is no corresponding record for this reference.
- 53Situm, A.; Rahman, M. A.; Goldberg, S.; Al-Abadleh, H. A. Spectral Characterization and Surface Complexation Modeling of Low Molecular Weight Organics on Hematite Nanoparticles: Role of Electrolytes in the Binding Mechanism. Environ. Sci. Nano 2016, 3 (4), 910– 926, DOI: 10.1039/C6EN00132GGoogle Scholar53https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtFanu7rJ&md5=e91af54a581246f69c549ae660b1793fSpectral characterization and surface complexation modeling of low molecular weight organics on hematite nanoparticles: role of electrolytes in the binding mechanismSitum, Arthur; Rahman, Mohammad A.; Goldberg, Sabine; Al-Abadleh, Hind A.Environmental Science: Nano (2016), 3 (4), 910-926CODEN: ESNNA4; ISSN:2051-8161. (Royal Society of Chemistry)Given the ubiquity of org.-metal oxide interfaces in environmental and medical systems, it is necessary to obtain mechanistic details at the mol. level from exptl. procedures that mimic real systems and conditions. We report herein the adsorption pH envelopes (range 9-5) isotherms at pH 7. These studies showed that the structure of the org. species influences the type and relative amts. of inner- vs. outer-sphere surface complexes. This has consequences on the surface charge as shown from electrolyte concn.-dependent studies. Example, citrate forms a mix of protonated monodentate inner-sphere complexes with one neg. charge and deprotonated outer-sphere complexes with net two neg. charges. Oxalate forms mostly doubly deprotonated outer-sphere complexes with inaccessible neighboring sites with contributions from deprotonated inner-sphere complexes. Lastly, pyrocatechol forms mostly bidentate inner-sphere complexes. Layering of interfacial electrolyte ions from KCl, NaCl and KBr, used to adjust the electrolyte concn., caused an overall enhancement in the amt. of adsorbed weakly-bonded citrate and oxalate. Also, hematite nanoparticles retain more adsorbed citrate and pyrocatechol than adsorbed oxalate when chloride or bromide was flowed as a neg.-charged weak desorbing agent at pH 7. These results have implications for the overall surface chem. of hematite nanoparticles in the presence of org. matter, particularly those contg. carboxylate and phenolate functional groups.
- 54Yeasmin, S.; Singh, B.; Kookana, R. S.; Farrell, M.; Sparks, D. L.; Johnston, C. T. Influence of Mineral Characteristics on the Retention of Low Molecular Weight Organic Compounds: A Batch Sorption-Desorption and ATR-FTIR Study. J. Colloid Interface Sci. 2014, 432, 246– 257, DOI: 10.1016/j.jcis.2014.06.036Google Scholar54https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1KgsLzF&md5=92fa8e5902c23052761dd5d856839544Influence of mineral characteristics on the retention of low molecular weight organic compounds: A batch sorption-desorption and ATR-FTIR studyYeasmin, Sabina; Singh, Balwant; Kookana, Rai S.; Farrell, Mark; Sparks, Donald L.; Johnston, Cliff T.Journal of Colloid and Interface Science (2014), 432 (), 246-257CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)Batch expts. were conducted to evaluate the sorption-desorption behavior of 14C-labeled carboxylic acids (citric and oxalic) and amino acids (glutamic, alanine, phenylalanine and lysine) on pure minerals (kaolinite, illite, montmorillonite, ferrihydrite and goethite). The sorption expts. were complemented by ATR-FTIR spectroscopy to gain possible mechanistic insight into the org. acids-mineral interactions. In terms of charge, the org. solutes ranged from strongly neg. (i.e., citric) to pos. charged solutes (i.e., lysine); similarly the mineral phases also ranged from pos. to neg. charged surfaces. In general, sorption of anionic carboxylic and glutamic acids was higher compared to the other compds. (except lysine). Cationic lysine showed a stronger affinity to permanently charged phyllosilicates than Fe oxides. The sorption of alanine and phenylalanine was consistently low for all minerals, with relatively higher sorption and lower desorption of phenylalanine than alanine. Overall, the role of carboxylic functional groups for the sorption and retention of these carboxylic and amino acids on Fe oxides (and kaolinite) and of amino group on 2:1 phyllosilicates was noticeable. Mineral properties (surface chem., sp. surface area), chem. of the org. compds. (pKa value, functional groups) and the equil. pH of the system together controlled the differences in sorption-desorption patterns. The results of this study aid to understand the effects of mineralogical and chem. factors that affect naturally occurring low mol. wt. org. compds. sorption under field conditions.
- 55Assis, M. B. d. S.; Werneck, I. H. S. R.; de Moraes, G. N.; Semaan, F. S.; Pacheco Pereira, R. Citrate-Capped Iron Oxide Nanoparticles: Ultrasound-Assisted Synthesis, Structure and Thermal Properties. Mater. Res. Express 2019, 6 (4), 045064, DOI: 10.1088/2053-1591/aaff2aGoogle ScholarThere is no corresponding record for this reference.
- 56Mamontov, E.; Vlcek, L.; Wesolowski, D. J.; Cummings, P. T.; Wang, W.; Anovitz, L. M.; Rosenqvist, J.; Brown, C. M.; Garcia Sakai, V. Dynamics and Structure of Hydration Water on Rutile and Cassiterite Nanopowders Studied by Quasielastic Neutron Scattering and Molecular Dynamics Simulations. J. Phys. Chem. C 2007, 111 (11), 4328– 4341, DOI: 10.1021/jp067242rGoogle Scholar56https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXitFKrtrs%253D&md5=bf6be7109e624e16c8f1e76a8a9994e8Dynamics and Structure of Hydration Water on Rutile and Cassiterite Nanopowders Studied by Quasielastic Neutron Scattering and Molecular Dynamics SimulationsMamontov, E.; Vlcek, L.; Wesolowski, D. J.; Cummings, P. T.; Wang, W.; Anovitz, L. M.; Rosenqvist, J.; Brown, C. M.; Garcia Sakai, V.Journal of Physical Chemistry C (2007), 111 (11), 4328-4341CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Quasielastic neutron scattering (QENS) expts. carried out using time-of-flight and backscattering neutron spectrometers with widely different energy resoln. and dynamic range revealed the diffusion dynamics of hydration H2O in nanopowder rutile (TiO2) and cassiterite (SnO2) that possess the rutile crystal structure with the (110) crystal face predominant on the surface. These isostructural oxides differ in their bulk dielec. consts., metal atom electronegativities, and lattice spacings, which may all contribute to differences in the structure and dynamics of sorbed H2O. When hydrated under ambient conditions, the nanopowders had similar levels of hydration: ∼3.5 (OH/H2O) mols. per Ti2O4 surface structural unit of TiO2 and ∼4.0 (OH/H2O) mols. per Sn2O4 surface unit of SnO2. Ab initio optimized classical mol. dynamics (MD) simulations of the (110) surfaces in contact with SPC/E H2O at these levels of hydration indicate 3 structurally distinct sorbed H2O layers L1, L2, and L3, where the L1 species are either assocd. H2O mols. or dissocd. hydroxyl groups in direct contact with the surface, L2 H2O mols. are hydrogen bonded to L1 and structural oxygen atoms at the surface, and L3 H2O mols. are more weakly bound. At the hydration levels studied, L3 is incomplete compared with axial oxygen d. profiles of bulk SPC/E H2O in contact with these surfaces, but the structure and dynamics of L1-L3 species are remarkably similar at full and reduced H2O coverage. Three hydration H2O diffusion components, on the time scale of a picosecond, tens of picoseconds, and a nanosecond could be extd. from the QENS spectra of both oxides. However, the spectral wt. of the faster components was significantly lower for SnO2 compared to TiO2. In TiO2 hydration H2O, the more strongly bound L2 H2O mols. exhibited slow (on the time scale of a nanosecond) dynamics characterized by super-Arrhenius, fragile behavior >220 K and the dynamic transition to Arrhenius, strong behavior at lower temps. The more loosely bound L3 H2O mols. in TiO2 exhibited faster dynamics with Arrhenius temp. dependence. However, the slow diffusion component in L2 hydration H2O on SnO2, also on the time scale of a nanosecond, showed little evidence of super-Arrhenius behavior or the fragile-to-strong transition. The occurrence of super-Arrhenius dynamic behavior in surface H2O is sensitive to the strength of interaction of the H2O mols. with the surface and the distribution of surface H2O mols. among the different hydration layers. Anal. of energy transfer spectra generated from the mol. dynamics simulations shows fast and intermediate dynamics in good agreement with the QENS time-of-flight results. Also demonstrated by the simulation is the fast (compared to 1 ns) exchange between the H2O mols. of the L2 and L3 hydration layers.
- 57Jørgensen, J. E.; Mosegaard, L.; Thomsen, L. E.; Jensen, T. R.; Hanson, J. C. Formation of γ-Fe2O3 Nanoparticles and Vacancy Ordering: An in Situ X-Ray Powder Diffraction Study. J. Solid State Chem. 2007, 180 (1), 180– 185, DOI: 10.1016/j.jssc.2006.09.033Google Scholar57https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXnt1Cisg%253D%253D&md5=dd741a3e27683eaeda044a7480f7d17dFormation of γ-Fe2O3 nanoparticles and vacancy ordering: An in situ X-ray powder diffraction studyJorgensen, Jens-Erik; Mosegaard, Lene; Thomsen, Line E.; Jensen, Torben R.; Hanson, Jonathan C.Journal of Solid State Chemistry (2007), 180 (1), 180-185CODEN: JSSCBI; ISSN:0022-4596. (Elsevier)The formation of maghemite, γ-Fe2O3 nanoparticles was studied by in situ x-ray powder diffraction. The maghemite was formed by thermal decompn. of an amorphous precursor compd. made by reacting lauric acid, CH3(CH2)10COOH with Fe(NO3)3·9H2O. Cubic γ-Fe2O3 was formed directly from the amorphous precursor and vacancy ordering starts ∼45 min later at 305° resulting in a tripled unit cell along the c-axis. The kinetics of grain growth was found to obey a power law with growth exponents n equal to 0.136(6) and 0.103(5) at 305 and 340°, resp. Particles with av. sizes of 12 and 13 nm were obtained in 86 and 76 min at 305 and 340°, resp. The structure of cubic and vacancy ordered phases of γ-Fe2O3 was studied at 305° by Rietveld refinements.
- 58Köhler, T.; Feoktystov, A.; Petracic, O.; Kentzinger, E.; Bhatnagar-Schöffmann, T.; Feygenson, M.; Nandakumaran, N.; Landers, J.; Wende, H.; Cervellino, A. Mechanism of Magnetization Reduction in Iron Oxide Nanoparticles. Nanoscale 2021, 13 (14), 6965– 6976, DOI: 10.1039/D0NR08615KGoogle ScholarThere is no corresponding record for this reference.
- 59Sinha, S. K.; Sirota, E. B.; Garoff, S.; Stanley, H. B. X-Ray and Neutron Scattering from Rough Surfaces. Phys. Rev. B 1988, 38 (4), 2297– 2311, DOI: 10.1103/PhysRevB.38.2297Google Scholar59https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2sfhtlejtQ%253D%253D&md5=6e8b80c49359bb2646efe482e4f14c34X-ray and neutron scattering from rough surfacesSinha; Sirota; Garoff; StanleyPhysical review. B, Condensed matter (1988), 38 (4), 2297-2311 ISSN:0163-1829.There is no expanded citation for this reference.
- 60Grapengeter, H. H.; Alefeld, B.; Kosfeld, R. An Investigation of Micro-Brownian Motions in Polydimethylsiloxane by Complementary Incoherent-Neutron-Scattering and Nuclear-Magnetic-Resonance Experiments below Room Temperature. Colloid Polym. Sci. 1987, 265, 226– 233, DOI: 10.1007/bf01412711Google Scholar60https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2sXhslOitLg%253D&md5=570054fa5d4021d5ff81dfb3d0f9a029An investigation of micro-Brownian motion in poly(dimethylsiloxane) by complementary incoherent neutron scattering and nuclear magnetic resonance experiments below room temperatureGrapengeter, H. H.; Alefeld, B.; Kosfeld, R.Colloid and Polymer Science (1987), 265 (3), 226-33CODEN: CPMSB6; ISSN:0303-402X.The random segmental rotational jump motions of Me groups in di-Me siloxane (mol. wt. 1.32 × 105) were studied by the 2 title techniques. Magnetic relaxation and line width expts. were complementary to incoherent neutron scattering fixed-window expts.; the principle of the fixed-window expts. was discussed in detail. Satisfactory agreement of these exptl. techniques was achieved in the detn. of the 2 model parameters of the motional processes in question, i.e. the activation energy and the preexponential factor of the Arrhenius relation made for the correlation time or jump time, resp.
- 61Mamontov, E.; Smith, R. W.; Billings, J. J.; Ramirez-Cuesta, A. J. Simple Analytical Model for Fitting QENS Data from Liquids. Phys. B: Condens. Matter 2019, 566, 50– 54, DOI: 10.1016/j.physb.2019.01.051Google ScholarThere is no corresponding record for this reference.
- 62Krynicki, K.; Green, C. D.; Sawyer, D. W. Pressure and Temperature Dependence of Self-Diffusion in Water. Faraday Discuss. Chem. Soc. 1978, 66, 199, DOI: 10.1039/dc9786600199Google Scholar62https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL3cXivVOisw%253D%253D&md5=09a108d79ddcb120ba31840466f2633bPressure and temperature dependence of self-diffusion in waterKrynicki, Kazimierz; Green, Christopher D.; Sawyer, David W.Faraday Discussions of the Chemical Society (1978), 66 (Struct. Motion Mol. Liq.), 199-208CODEN: FDCSB7; ISSN:0301-7249.The self-diffusion coeff. (D) for pure liq. H2O was detd. at 275.2-498.2 K and ≤1.75 kbar by the proton spin echo method. Values of D agree with available published results. The results were discussed in terms of several theories. The Stokes-Einstein relation is obeyed in the slipping boundary limit. The cubic cell model of G. Houghton (1964) accounts satisfactorily for the exptl. D values, particularly at higher temps. A modified hard-sphere theory is more satisfactory than the simple hard-sphere theory esp. at low temps. An activation anal. at const. d. shows that H2O behaves very differently from nonassocd. liqs., and suggests that an increase in both temp. and pressure leads to an increase in the fraction of free unbonded H2O mols. A free-vol. anal. leads to a modified Arrhenius equation which involves pressure-dependent terms. The semiempirical equation describes the results within exptl. error and predicts a glass temp. at 115 K which is in reasonable agreement with values obtained by other method.
- 63Bée, M. Quasielastic Neutron Scattering; Adam Hilger, 1988.Google ScholarThere is no corresponding record for this reference.
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Abstract
Figure 1
Figure 1. (a) Intensity at 2, 120, and 300 K from the EFWS, plotted along with the NPD pattern of IONPs measured at RT; (b) intensity at the energy offset of 3 μeV and temperatures of 5, 120, and 300 K.
Figure 2
Figure 3
Figure 3. ERS measured at 360 K at IN16B in BATS mode for an H2O-equilibrated (a) and at 370 K on the BS Emu for a D2O-equilibrated sample (b).
Figure 4
Figure 4. Simultaneous fit of the EFWS (a), IFWS (b), and ERS at 340 (c) and 380 K (d).
Figure 5
Figure 5. (a) Activation energy and relaxation time limit of citrate motion; (b) HWHM of citrate Lorentzian from H2O- and D2O-equilibrated samples (370 K); (c) HWHM and the amplitude of water Lorentzian from simultaneous fit (360 K).
Figure 6
Figure 6. Amplitudes of the Lorentzian describing citrate motion fitted with continuous diffusion on a circle.
References
This article references 63 other publications.
- 1Roca, A. G.; Gutiérrez, L.; Gavilán, H.; Fortes Brollo, M. E.; Veintemillas-Verdaguer, S.; Morales, M.; del, P. Design Strategies for Shape-Controlled Magnetic Iron Oxide Nanoparticles. Adv. Drug Delivery Rev. 2019, 138, 68– 104, DOI: 10.1016/j.addr.2018.12.0081https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXisF2hu77O&md5=8b273b8e14cc158782f32026597e260fDesign strategies for shape-controlled magnetic iron oxide nanoparticlesRoca, Alejandro G.; Gutierrez, Lucia; Gavilan, Helena; Fortes Brollo, Maria Eugenia; Veintemillas-Verdaguer, Sabino; Morales, Maria del PuertoAdvanced Drug Delivery Reviews (2019), 138 (), 68-104CODEN: ADDREP; ISSN:0169-409X. (Elsevier B.V.)Ferrimagnetic iron oxide nanoparticles (magnetite or maghemite) have been the subject of an intense research, not only for fundamental research but also for their potentiality in a widespread no. of practical applications. Most of these studies were focused on nanoparticles with spherical morphol. but recently there is an emerging interest on anisometric nanoparticles. This review is focused on the synthesis routes for the prodn. of uniform anisometric magnetite/maghemite nanoparticles with different morphologies like cubes, rods, disks, flowers and many others, such as hollow spheres, worms, stars or tetrapods. We critically analyzed those procedures, detected the key parameters governing the prodn. of these nanoparticles with particular emphasis in the role of the ligands in the final nanoparticle morphol. The main structural and magnetic features as well as the nanotoxicity as a function of the nanoparticle morphol. are also described. Finally, the impact of each morphol. on the different biomedical applications (hyperthermia, magnetic resonance imaging and drug delivery) are analyzed in detail. We would like to dedicate this work to Professor Carlos J. Serna, Instituto de Ciencia de Materiales de Madrid, ICMM/CSIC, for his outstanding contribution in the field of monodispersed colloids and iron oxide nanoparticles. We would like to express our gratitude for all these years of support and inspiration on the occasion of his retirement.
- 2Amstad, E.; Textor, M.; Reimhult, E. Stabilization and Functionalization of Iron Oxide Nanoparticles for Biomedical Applications. Nanoscale 2011, 3 (7), 2819, DOI: 10.1039/c1nr10173k2https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXptVahsLc%253D&md5=6d60b836b1b9c9a582219173529e128eStabilization and functionalization of iron oxide nanoparticles for biomedical applicationsAmstad, Esther; Textor, Marcus; Reimhult, ErikNanoscale (2011), 3 (7), 2819-2843CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)A review. Superparamagnetic iron oxide nanoparticles (NPs) are used in a rapidly expanding no. of research and practical applications in the biomedical field, including magnetic cell labeling sepn. and tracking, for therapeutic purposes in hyperthermia and drug delivery, and for diagnostic purposes, e.g., as contrast agents for magnetic resonance imaging. These applications require good NP stability at physiol. conditions, close control over NP size and controlled surface presentation of functionalities. This review is focused on different aspects of the stability of superparamagnetic iron oxide NPs, from its practical definition to its implementation by mol. design of the dispersant shell around the iron oxide core and further on to its influence on the magnetic properties of the superparamagnetic iron oxide NPs. Special attention is given to the selection of mol. anchors for the dispersant shell, because of their importance to ensure colloidal and functional stability of sterically stabilized superparamagnetic iron oxide NPs. The authors further detail how dispersants were optimized to gain close control over iron oxide NP stability, size and functionalities by independently considering the influences of anchors and the attached sterically repulsive polymer brushes. A crit. evaluation of different strategies to stabilize and functionalize core-shell superparamagnetic iron oxide NPs as well as a brief introduction to characterization methods to compare those strategies is given.
- 3Vangijzegem, T.; Stanicki, D.; Laurent, S. Magnetic Iron Oxide Nanoparticles for Drug Delivery: Applications and Characteristics. Expert Opin. Drug Delivery 2019, 16 (1), 69– 78, DOI: 10.1080/17425247.2019.15546473https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXisVKitLzF&md5=6c7ea014c0d99a2820229cd9e3b77dc6Magnetic iron oxide nanoparticles for drug delivery: applications and characteristicsVangijzegem, Thomas; Stanicki, Dimitri; Laurent, SophieExpert Opinion on Drug Delivery (2019), 16 (1), 69-78CODEN: EODDAW; ISSN:1742-5247. (Taylor & Francis Ltd.)A review. : For many years, the controlled delivery of therapeutic compds. has been a matter of great interest in the field of nanomedicine. Among the wide amt. of drug nanocarriers, magnetic iron oxide nanoparticles (IONs) stand out from the crowd and constitute robust nanoplatforms since they can achieve high drug loading as well as targeting abilities stemming from their remarkable properties (magnetic and biol. properties). These applications require precise design of the nanoparticles regarding several parameters which must be considered together in order to attain highest therapeutic efficacy.: This short review presents recent developments in the field of cancer targeted drug delivery using magnetic nanocarriers as drug delivery systems.: The design of nanocarriers enabling efficient delivery of therapeutic compds. toward targeted locations is one of the major area of research in the targeted drug delivery field. By precisely shaping the structural properties of the iron oxide nanoparticles, drugs loaded onto the nanoparticles can be efficiently guided and selectively delivered toward targeted locations. With these goals in mind, special attention should be given to the pharmacokinetics and in vivo behavior of the developed nanocarriers.
- 4Oehlsen, O.; Cervantes-Ramírez, S. I.; Cervantes-Avilés, P.; Medina-Velo, I. A. Approaches on Ferrofluid Synthesis and Applications: Current Status and Future Perspectives. ACS Omega 2022, 7 (4), 3134– 3150, DOI: 10.1021/acsomega.1c056314https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhsF2ks7Y%253D&md5=05058713a3a8d2acaf9413ea8fbd9f7fApproaches on Ferrofluid Synthesis and Applications: Current Status and Future PerspectivesOehlsen, Oscar; Cervantes-Ramirez, Sussy I.; Cervantes-Aviles, Pabel; Medina-Velo, Illya A.ACS Omega (2022), 7 (4), 3134-3150CODEN: ACSODF; ISSN:2470-1343. (American Chemical Society)A review. Ferrofluids are colloidal suspensions of iron oxide nanoparticles (IONPs) within aq. or nonaq. liqs. that exhibit strong magnetic properties. These magnetic properties allow ferrofluids to be manipulated and controlled when exposed to magnetic fields. This review aims to provide the current scope and research opportunities regarding the methods of synthesis of nanoparticles, surfactants, and carrier liqs. for ferrofluid prodn., along with the rheol. and applications of ferrofluids within the fields of medicine, water treatment, and mech. engineering. A ferrofluid is composed of IONPs, a surfactant that coats the magnetic IONPs to prevent agglomeration, and a carrier liq. that suspends the IONPs. Copptn. and thermal decompn. are the main methods used for the synthesis of IONPs. Despite the fact that thermal decompn. provides precise control on the nanoparticle size, copptn. is the most used method, even when the oxidn. of iron can occur. This oxidn. alters the ratio of maghemite/magnetite, influencing the magnetic properties of ferrofluids. Strategies to overcome iron oxidn. have been proposed, such as the use of an inert atm., adjusting the Fe(II) and Fe(III) ratio to 1:2, and the exploration of other metals with the oxidn. state +2. Surfactants and carrier liqs. are chosen according to the ferrofluid application to ensure stability. Hence, a compatible carrier liq. (polar or nonpolar) is selected, and then, a surfactant, mainly a polymer, is embedded in the IONPs, providing a steric barrier. Due to the variety of surfactants and carrier liqs., the rheol. properties of ferrofluids are an important response variable evaluated when synthesizing ferrofluids. There are many reported applications of ferrofluids, including biosensing, medical imaging, medicinal therapy, magnetic nanoemulsions, and magnetic impedance. Other applications include water treatment, energy harvesting and transfer, and vibration control. To progress from synthesis to applications, research is still ongoing to ensure control of the ferrofluids' properties.
- 5Saraswathy, A.; Nazeer, S. S.; Jeevan, M.; Nimi, N.; Arumugam, S.; Harikrishnan, V. S.; Varma, P. H.; Jayasree, R. S. Citrate Coated Iron Oxide Nanoparticles with Enhanced Relaxivity for in Vivo Magnetic Resonance Imaging of Liver Fibrosis. Colloids Surf., B 2014, 117, 216– 224, DOI: 10.1016/j.colsurfb.2014.02.0345https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXntFynurs%253D&md5=f566d22cb9e25fb6162627fa2e1c216cCitrate coated iron oxide nanoparticles with enhanced relaxivity for in vivo magnetic resonance imaging of liver fibrosisSaraswathy, Ariya; Nazeer, Shaiju S.; Jeevan, Madhumol; Nimi, Nirmala; Arumugam, Sabareeswaran; Harikrishnan, Vijayakumar S.; Varma, P. R. Harikrishna; Jayasree, Ramapurath S.Colloids and Surfaces, B: Biointerfaces (2014), 117 (), 216-224CODEN: CSBBEQ; ISSN:0927-7765. (Elsevier B.V.)Superparamagnetic iron oxide nanoparticles are widely used for the magnetic resonance imaging (MRI) applications. The surface characteristics, magnetic properties, size and targeting efficiency of the material are crucial factors for using the same as contrast agents. We report a simple synthesis method of citrate coated iron oxide nanoparticles and its systematic characterization. The developed system is highly water dispersible with an av. particle size of 12 nm. The particles in water are monodisperse and are found to be stable over long periods. The efficiency of the material to de-phase water proton has been studied for various concns. of iron using longitudinal (T1) and transverse (T2) weighted MRI. The coating thickness of the nanoparticle was optimized so that they exhibited a high transverse to longitudinal relaxivity (r2/r1) ratio of 37.92. A clear dose-dependent contrast enhancement was obsd. in T2 weighted in vivo MR imaging of liver fibrosis model in rodents. The labeling efficacy of the particle and the intracellular magnetic relaxivity were also investigated and presented. The particles were also tested for blood and cellular compatibility studies. Development of fibrosis and presence of iron in the liver was confirmed by histopathol. anal. From this study, we conclude that the citrate coated ultra small superparamagnetic iron oxide nanoparticles (C-USPION) with optimized parameters like particle size and magnetic property are capable of producing good MR contrast in imaging of liver diseases.
- 6Abo-zeid, Y.; Ismail, N. S. M.; McLean, G. R.; Hamdy, N. M. A Molecular Docking Study Repurposes FDA Approved Iron Oxide Nanoparticles to Treat and Control COVID-19 Infection. Eur. J. Pharm. Sci. 2020, 153, 105465, DOI: 10.1016/j.ejps.2020.1054656https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsVWgsL3F&md5=2f7c5e2b2fd7ec34245b50df5744ef49A molecular docking study repurposes FDA approved iron oxide nanoparticles to treat and control COVID-19 infectionAbo-zeid, Yasmin; Ismail, Nasser. S.; McLean, Gary. R.; Hamdy, Nadia. M.European Journal of Pharmaceutical Sciences (2020), 153 (), 105465CODEN: EPSCED; ISSN:0928-0987. (Elsevier B.V.)COVID-19, is a disease resulting from the SARS-CoV-2 global pandemic. Due to the current global emergency and the length of time required to develop specific antiviral agent(s) and a vaccine for SARS-CoV-2, the world health organization (WHO) adopted the strategy of repurposing existing medications to treat COVID-19. Iron oxide nanoparticles (IONPs) were previously approved by the US food and drug administration (FDA) for anemia treatment and studies have also demonstrated its antiviral activity in vitro. Therefore, we performed a docking study to explore the interaction of IONPs (Fe2O3 and Fe3O4) with the spike protein receptor binding domain (S1-RBD) of SARS-CoV-2 that is required for virus attachment to the host cell receptors. A similar docking anal. was also performed with hepatitis C virus (HCV) glycoproteins E1 and E2. These studies revealed that both Fe2O3 and Fe3O4 interacted efficiently with the SARS-CoV-2 S1-RBD and to HCV glycoproteins, E1 and E2. Fe3O4 formed a more stable complex with S1-RBD whereas Fe2O3 favored HCV E1 and E2. These interactions of IONPs are expected to be assocd. with viral proteins conformational changes and hence, viral inactivation. Therefore, we recommend FDA-approved-IONPs to proceed for COVID-19 treatment clin. trials.
- 7Le Goas, M.; Saber, J.; Bolívar, S. G.; Rabanel, J.-M.; Awogni, J.-M.; Boffito, D. C.; Banquy, X. (In)Stability of Ligands at the Surface of Inorganic Nanoparticles: A Forgotten Question in Nanomedicine?. Nano Today 2022, 45, 101516, DOI: 10.1016/j.nantod.2022.1015167https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhvFeiu7jL&md5=b756abce02d9bf830a77c27681167480Design inorganic nanoparticles based medicines with better clinical efficacy and translation abilityLe Goas, Marine; Saber, Justine; Bolivar, Sara Gonzalez; Rabanel, Jean-Michel; Awogni, Jean-Marc; Boffito, Daria C.; Banquy, XavierNano Today (2022), 45 (), 101516CODEN: NTAOCG; ISSN:1748-0132. (Elsevier Ltd.)A review. Multiple inorg. nanoparticles (NPs) are currently being developed for nanomedicine. Various core materials and shapes are explored, but they all display a common hybrid structure, with org. ligands on their surface. These ligands play a key role in the NP colloidal stability and surface properties, and therefore strongly impact the biol. fate of the NPs. However, ligands may be subject to reorganization, degrdn., desorption, and exchange, both during their shelf-life and upon exposure to a biol. environment. The question of ligand (in)stability at the surface of inorg. NPs has been little addressed in the literature. The goal of this review is to provide a portrait of this crit. phenomenon. We identify and review here the different mechanisms likely to promote ligand instability and discuss the resulting biol. fate of ligands. This review is aimed to provide a better understanding of these phenomena and to help researchers to design NP-based medicines with better clin. efficacy and translation ability.
- 8Wang, X.; Wang, X.; Bai, X.; Yan, L.; Liu, T.; Wang, M.; Song, Y.; Hu, G.; Gu, Z.; Miao, Q.; Chen, C. Nanoparticle Ligand Exchange and Its Effects at the Nanoparticle-Cell Membrane Interface. Nano Lett. 2019, 19 (1), 8– 18, DOI: 10.1021/acs.nanolett.8b026388https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhvFWksbbN&md5=c175e516322e4c6a63de67fd362e4081Nanoparticle Ligand Exchange and Its Effects at the Nanoparticle-Cell Membrane InterfaceWang, Xinyi; Wang, Xiaofeng; Bai, Xuan; Yan, Liang; Liu, Tao; Wang, Mingzhe; Song, Youtao; Hu, Guoqing; Gu, Zhanjun; Miao, Qing; Chen, ChunyingNano Letters (2019), 19 (1), 8-18CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)The nanoparticle (nano)-cell membrane interface is one of the most important interactions detg. the fate of nanoparticles (NPs), which can stimulate a series of biol. events, allowing theranostic and other biomedical applications. So far, there remains a lack of knowledge about the mechanisms governing the nanoparticle-cell membrane interface, esp. the impact of ligand exchange, in which mols. on the nanosurface become replaced with components of the cell membrane, resulting in unique interfacial phenomena. Herein, we describe a family of gold nanoparticles (AuNPs) of the same core size (∼13 nm core), modified with 12 different kinds of surface ligands, and the effects of their exchangeable ligands on both nanoparticle-supported lipid bilayers (SLBs) and nanoparticle-natural cell membrane interfaces. The ligands are categorized according to their mol. wt., charge, and bonding modes (physisorption or chemisorption). Importantly, we found that, depending on the adsorption affinity and size of ligand mols., physisorbed ligands on the surface of NPs can be exchanged with lipid mols. At a ligand exchange-dominated interface, the AuNPs typically aggregated into an ordered monolayer in the lipid bilayers, subsequently affecting cell membrane integrity, NP uptake efficiency, and the NP endocytosis pathways. These findings advance our understanding of the underlying mechanisms of the biol. effects of nanoparticles from a new point of view and will aid in the design of novel, safe, and effective nanomaterials for biomedicine.
- 9Liu, M.; Ma, Y.; Wang, R. Y. Modifying Thermal Transport in Colloidal Nanocrystal Solids with Surface Chemistry. ACS Nano 2015, 9 (12), 12079– 12087, DOI: 10.1021/acsnano.5b050859https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhsl2htLvI&md5=c17ac1fbde443b24b138c017bd2dacf3Modifying Thermal Transport in Colloidal Nanocrystal Solids with Surface ChemistryLiu, Minglu; Ma, Yuanyu; Wang, Robert Y.ACS Nano (2015), 9 (12), 12079-12087CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)The effect of surface chem. on thermal transport in colloidal nanocrystal (NC) solids has been studied. Using PbS NCs as a model system, the authors varied ligand binding group (thiol, amine, and at. halides), ligand length (ethanedithiol, butanedithiol, hexanedithiol, and octanedithiol), and NC diam. (3.3-8.2 nm). The expts. revealed several findings: (i) The ligand choice could vary the NC solid thermal cond. by up to a factor of 2.5; (ii) the ligand binding strength to the NC core did not significantly impact thermal cond.; (iii) reducing the ligand length could decrease the interparticle distance, which increases thermal cond.; (iv) increasing the NC diam. increased thermal cond.; and (v) the effect of surface chem. could exceed the effect of NC diam. and becomes more pronounced as NC diam. decreases. The thermal cond. of NC solids could be varied by an overall factor of 4, from ∼0.1-0.4 W/m-K. These findings were complemented with effective medium approxn. modeling and identify thermal transport in the ligand matrix as the rate-limiter for thermal transport. By combining these modeling results with our exptl. observations, the authors conclude that future efforts to increase thermal cond. in NC solids should focus on the ligand-ligand interface between neighboring NCs.
- 10Bian, H.; Li, J.; Chen, H.; Yuan, K.; Wen, X.; Li, Y.; Sun, Z.; Zheng, J. Molecular Conformations and Dynamics on Surfaces of Gold Nanoparticles Probed with Multiple-Mode Multiple-Dimensional Infrared Spectroscopy. J. Phys. Chem. C 2012, 116 (14), 7913– 7924, DOI: 10.1021/jp300970p10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XjvFKltL8%253D&md5=c4685c294a30ed5ebb1e37427354948bMolecular Conformations and Dynamics on Surfaces of Gold Nanoparticles Probed with Multiple-Mode Multiple-Dimensional Infrared SpectroscopyBian, Hongtao; Li, Jiebo; Chen, Hailong; Yuan, Kaijun; Wen, Xiewen; Li, Yaqin; Sun, Zhigang; Zheng, JunrongJournal of Physical Chemistry C (2012), 116 (14), 7913-7924CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Knowledge about mol. conformations and nuclear and electronic motions on surfaces of metal nanomaterials is crit. for many applications but extremely difficult to obtain. Valuable information of this sort can be detd. using multiple-mode multiple-dimensional vibrational spectroscopy. A model compd., 4-mercaptophenol, on the surface of 3.5 nm gold nanoparticles demonstrates the method. Its 3-dimensional mol. conformations and vibrational dynamics on the particle surfaces were detd. with the method. The exptl. results imply that on the particle surfaces, the ligand mols. cannot form energy-optimized hydrogen bonds because of the surface geometry constraint. The conclusion is supported with expts. on the ligand mols. in the cryst. phase and in a dil. soln. The authors' expts. also showed that the effect of the particle surface nonadiabatic electron/vibration coupling does not play a significant role in the vibrational relaxation of high-frequency modes (>1000 cm-1) ∼3 Å away from the surface. Simple theor. calcns. support this observation. The method holds promise as a general tool for the studies of mol. structures and dynamics on the surfaces of nanomaterials. The capability of resolving 3-dimensional mol. conformations on nanomaterials surfaces is expected to be helpful for understanding specific intermol. interactions and conformation-selective reactions (e.g., chirality selectivity) on the surfaces of these materials.
- 11Ionita, P.; Volkov, A.; Jeschke, G.; Chechik, V. Lateral Diffusion of Thiol Ligands on the Surface of Au Nanoparticles: An Electron Paramagnetic Resonance Study. Anal. Chem. 2008, 80 (1), 95– 106, DOI: 10.1021/ac071266s11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtlGis7vI&md5=a33081cc57b2c6b5b55c0848f979db88Lateral Diffusion of Thiol Ligands on the Surface of Au Nanoparticles: An Electron Paramagnetic Resonance StudyIonita, Petre; Volkov, Aleksei; Jeschke, Gunnar; Chechik, VictorAnalytical Chemistry (Washington, DC, United States) (2008), 80 (1), 95-106CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)The lateral mobility of the thiolate ligands on the surface of Au nanoparticles was probed by EPR spectroscopy. This was achieved by using bisnitroxide ligands, which contained a disulfide group (to ensure attachment to the Au surface) and a cleavable ester bridge connecting the two spin-labeled branches of the mol. Upon adsorption of these ligands on the surface of Au nanoparticles, the two spin-labeled branches were held next to each other by the ester bridge as evidenced by the spin-spin interactions. Cleavage of the bridge removed the link that kept the branches together. CW and pulsed EPR (DEER) expts. showed that the av. distance between the adjacent thiolate branches on the Au nanoparticle surface only marginally increased after cleaving the bridge and thermal treatment. This implies that the lateral diffusion of thiolate ligands on the nanoparticle surface is very slow at room temp. and takes hours even at elevated temps. (90°C). The changes in the distance distribution obsd. at high temp. are likely due to ligands hopping between the nanoparticles rather than diffusing on the particle surface.
- 12Dulle, M.; Jaber, S.; Rosenfeldt, S.; Radulescu, A.; Förster, S.; Mulvaney, P.; Karg, M. Plasmonic Gold-Poly(N-Isopropylacrylamide) Core-Shell Colloids with Homogeneous Density Profiles: A Small Angle Scattering Study. Phys. Chem. Chem. Phys. 2015, 17 (2), 1354– 1367, DOI: 10.1039/C4CP04816DThere is no corresponding record for this reference.
- 13Redel, E.; Walter, M.; Thomann, R.; Vollmer, C.; Hussein, L.; Scherer, H.; Krüger, M.; Janiak, C. Synthesis, Stabilization, Functionalization and, DFT Calculations of Gold Nanoparticles in Fluorous Phases (PTFE and Ionic Liquids). Chem.─Eur. J. 2009, 15 (39), 10047– 10059, DOI: 10.1002/chem.200900301There is no corresponding record for this reference.
- 14Wu, Z.-P.; Shan, S.; Zang, S.-Q.; Zhong, C.-J. Dynamic Core-Shell and Alloy Structures of Multimetallic Nanomaterials and Their Catalytic Synergies. Acc. Chem. Res. 2020, 53 (12), 2913– 2924, DOI: 10.1021/acs.accounts.0c0056414https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXit1yns7jI&md5=d45eea85fb31c7c4b82f998aefb2d1e3Dynamic Core-Shell and Alloy Structures of Multimetallic Nanomaterials and Their Catalytic SynergiesWu, Zhi-Peng; Shan, Shiyao; Zang, Shuang-Quan; Zhong, Chuan-JianAccounts of Chemical Research (2020), 53 (12), 2913-2924CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)Conspectus: Multimetallic nanomaterials contg. noble metals (NM) and non-noble 3d-transition metals (3d-TMs) exhibit unique catalytic properties as a result of the synergistic combination of NMs and 3d-TMs in the nanostructure. The exploration of such a synergy depends heavily on the understanding of the at.-scale structural details of NMs and 3d-TMs in the nanomaterials. This has attracted a great deal of recent interest in the field of catalysis science, esp. concerning the core-shell and alloy nanostructures. A rarely asked question of fundamental significance is how the core-shell and alloy structural arrangements of atoms in the multimetallic nanomaterials dynamically change under reaction conditions, including reaction temp., surface adsorbate, chem. environment, applied electrochem. potential, etc. The dynamic evolution of the core-shell/alloy structures under the reaction conditions plays a crucial role in the catalytic performance of the multimetallic nanocatalysts. This Account focuses on the dynamic structure characteristics for several different types of compn.-tunable alloy and core-shell nanomaterials, including phase-segregated, elemental-enriched, dynamically evolved, and structurally different core-shell structures. In addn. to outlining core-shell/alloy structure formation via processes such as seed-mediated growth, thermochem. calcination, adsorbate-induced evolution, chem. dealloying, underpotential deposition/galvanic displacement, etc., this Account will highlight the progress in understanding the dynamic core-shell/alloy structures under chem. or catalytic reaction conditions, which has become an important focal point of the research fronts in catalysis and electrocatalysis. The employment of advanced techniques, esp. in situ/operando synchrotron high-energy X-ray diffraction and pair distribution function analyses, has provided significant insights into the dynamic evolution processes of NM/3d-TM nanocatalysts under electrocatalytic or fuel cell operating conditions. Examples will highlight Pt- or Pd-based nanoparticles and nanowires alloyed with various 3d-TMs with a focus on their structural evolution under reaction conditions. While the dynamic process is complex, the ability to gain an insight into the evolution of core-shell and alloy structures under the catalytic reaction condition is essential for advancing the design of multimetallic nanocatalysts. This Account serves as a springboard from fundamental understanding of the core-shell and alloy structural dynamics to the various applications of nanostructured catalysts/electrocatalysts, esp. in the fronts of energy and environmental sustainability.
- 15Harris, R. A.; van der Walt, H.; Shumbula, P. M. Molecular Dynamics Study on Iron Oxide Nanoparticles Stabilised with Sebacic Acid and 1,10-Decanediol Surfactants. J. Mol. Struct. 2013, 1048, 18– 26, DOI: 10.1016/j.molstruc.2013.05.02615https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXht1Sktb%252FL&md5=1e6efa1c77c8b90cca69dfade6f32338Molecular dynamics study on iron oxide nanoparticles stabilized with Sebacic Acid and 1,10-Decanediol surfactantsHarris, R. A.; van der Walt, H.; Shumbula, P. M.Journal of Molecular Structure (2013), 1048 (), 18-26CODEN: JMOSB4; ISSN:0022-2860. (Elsevier B.V.)By using mol. dynamics in canonical ensemble (const. atom no., vol. and temp. (NVT)) the adsorption of sebacic acid (SA) and 1,10-decanediol (DD) onto the surfaces of an iron-oxide nanoparticle was simulated. The nanoparticle was built by taking into account the inverse spinel structure of a stoichiometric magnetite and the valence of the iron ions (Fe2+AFe2+BFe2+B where A and B stand for tetrahedral and octahedral sites, resp.). This study serves to det. theor. whether surfactants like SA or DD act as a better stabilizing agent for iron oxide nanoparticles of diams. ≥ 2.6 nm. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements on iron oxide nanoparticles stabilized with SA- and DD surfactants were obtained and compared to the simulated results. Unagglomerated nanoparticles with well-defined edges were obsd. during TEM for DD stabilized particles and a smaller particle size could be calcd. for these nanoparticles from XRD patterns. It is concluded that DD stabilizes an iron-oxide nanoparticle better than SA because of the difference in the no. of oxygen atoms on the resp. functional groups.
- 16Woehrle, G. H.; Brown, L. O.; Hutchison, J. E. Thiol-Functionalized, 1.5-Nm Gold Nanoparticles through Ligand Exchange Reactions: Scope and Mechanism of Ligand Exchange. J. Am. Chem. Soc. 2005, 127 (7), 2172– 2183, DOI: 10.1021/ja045771816https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXmslWjsA%253D%253D&md5=22c2b3772b041df9a0e7b43ce580c9e5Thiol-Functionalized, 1.5-nm Gold Nanoparticles through Ligand Exchange Reactions: Scope and Mechanism of Ligand ExchangeWoehrle, Gerd H.; Brown, Leif O.; Hutchison, James E.Journal of the American Chemical Society (2005), 127 (7), 2172-2183CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Ligand exchange reactions of 1.5-nm triphenylphosphine-stabilized nanoparticles with ω-functionalized thiols provides a versatile approach to functionalized, 1.5-nm gold nanoparticles from a single precursor. We describe the broad scope of this method and the first mechanistic investigation of thiol-for-phosphine ligand exchanges. The method is convenient and practical and tolerates a surprisingly wide variety of technol. important functional groups while producing very stable nanoparticles that essentially preserve the small core size and size dispersity of the precursor particle. The mechanistic studies reveal a novel three-stage mechanism that can be used to control the extent of ligand exchange. During the first stage of the exchange, AuCl(PPh3) is liberated, followed by replacement of the remaining phosphine ligands as PPh3 (assisted by gold complexes in soln.). The final stage involves completion and reorganization of the thiol-based ligand shell.
- 17Price, W. S. Pulsed-Field Gradient Nuclear Magnetic Resonance as a Tool for Studying Translational Diffusion: Part 1. Basic Theory. Concepts Magn. Reson. 1997, 9 (5), 299– 336, DOI: 10.1002/(SICI)1099-0534(1997)9:5<299::AID-CMR2>3.0.CO;2-U17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2sXlvV2hu7Y%253D&md5=59f3537cc7bfbff4e02ad0b97e7721a8Pulsed-field gradient nuclear magnetic resonance as a tool for studying translational diffusion: Part 1. Basic theoryPrice, William S.Concepts in Magnetic Resonance (1997), 9 (5), 299-336CODEN: CMAEEM; ISSN:1043-7347. (Wiley)A review with 125 refs. Translational diffusion is the most fundamental form of transport in chem. and biochem. systems. Pulsed-field gradient NMR provides a convenient and noninvasive means for measuring translational motion. In this method the attenuation of the echo signal from a Hahn spin-echo pulse sequence contg. a magnetic field gradient pulse in each τ period was used to measure the displacement of the obsd. spins. The phys. basis of this method is considered. Starting from the Bloch equations contg. diffusion terms, the (anal.) equation linking the echo attenuation to the diffusion of the spin for the case of unrestricted isotropic diffusion is derived. When the motion of the spin occurs within a confined geometry or is anisotropic, such as in in vivo systems, the echo attenuation also yields information on the surrounding structure, but as the anal. approach becomes math. intractable, approx. or numerical means must be used to ext. the motional information. Two common approxns. are considered and their limitations are examd. Measurements in anisotropic systems are also considered.
- 18Polito, L.; Colombo, M.; Monti, D.; Melato, S.; Caneva, E.; Prosperi, D. Resolving the Structure of Ligands Bound to the Surface of Superparamagnetic Iron Oxide Nanoparticles by High-Resolution Magic-Angle Spinning NMR Spectroscopy. J. Am. Chem. Soc. 2008, 130 (38), 12712– 12724, DOI: 10.1021/ja802479n18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtVOqt7vJ&md5=a5f2153f3313279ca76f650f10999f56Resolving the Structure of Ligands Bound to the Surface of Superparamagnetic Iron Oxide Nanoparticles by High-Resolution Magic-Angle Spinning NMR SpectroscopyPolito, Laura; Colombo, Miriam; Monti, Diego; Melato, Sergio; Caneva, Enrico; Prosperi, DavideJournal of the American Chemical Society (2008), 130 (38), 12712-12724CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)A major challenge in magnetic nanoparticle synthesis and (bio)functionalization concerns the precise characterization of the nanoparticle surface ligands. We report the first anal. NMR investigation of org. ligands stably anchored on the surface of superparamagnetic nanoparticles (MNPs) through the development of a new exptl. application of high-resoln. magic-angle spinning (HRMAS). The conceptual advance here is that the HRMAS technique, already being used for MAS NMR anal. of gels and semisolid matrixes, enables the fine-structure-resolved characterization of even complex org. mols. bound to paramagnetic nanocrystals, such as nanosized iron oxides, by strongly decreasing the effects of paramagnetic disturbances. This method led to detail-rich, well-resolved 1H NMR spectra, often with highly structured first-order couplings, essential in the interpretation of the data. This HRMAS application was first evaluated and optimized using simple ligands widely used as surfactants in MNP synthesis and conjugation. Next, the methodol. was assessed through the structure detn. of complex mol. architectures, such as those involved in MNP3 and MNP4. The comparison with conventional probes evidences that HRMAS makes it possible to work with considerably higher concns., thus avoiding the loss of structural information. Consistent 2D homonuclear 1H-1H and 1H-13C heteronuclear single-quantum coherence correlation spectra were also obtained, providing reliable elements on proton signal assignments and carbon characterization and opening the way to 13C NMR detn. Notably, combining the exptl. evidence from HRMAS 1H NMR and diffusion-ordered spectroscopy performed on the hybrid nanoparticle dispersion confirmed that the ligands were tightly bound to the particle surface when they were dispersed in a ligand-free solvent, while they rapidly exchanged when an excess of free ligand was present in soln. In addn. to HRMAS NMR, matrix-assisted laser desorption ionization time-of-flight MS anal. of modified MNPs proved very valuable in ligand mass identification, thus giving a sound support to NMR characterization achievements.
- 19Hempelmann, R. Quasielastic Neutron Scattering and Solid State Diffusion; Oxford University Press: Oxford, 2000; . DOI: 10.1093/acprof:oso/9780198517436.001.0001 .There is no corresponding record for this reference.
- 20Sears, V. F. Neutron Scattering Lengths and Cross Sections. Neutron News 1992, 3 (3), 26– 37, DOI: 10.1080/10448639208218770There is no corresponding record for this reference.
- 21Marry, V.; Dubois, E.; Malikova, N.; Breu, J.; Haussler, W. Anisotropy of Water Dynamics in Clays: Insights from Molecular Simulations for Experimental QENS Analysis. J. Phys. Chem. C 2013, 117 (29), 15106– 15115, DOI: 10.1021/jp403501h21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtValsb3I&md5=a0c48b69ea675dbe2a49254000d146a9Anisotropy of Water Dynamics in Clays: Insights from Molecular Simulations for Experimental QENS AnalysisMarry, V.; Dubois, E.; Malikova, N.; Breu, J.; Haussler, W.Journal of Physical Chemistry C (2013), 117 (29), 15106-15115CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)We measure H2O dynamics in a well-defined synthetic hectorite clay by the neutron spin echo technique, in the temp. range from 240 to 347 K. The interlayer spaces of this anisotropic material contain two layers of confined water, corresponding to the so-called bihydrated state. We analyze the exptl. data in light of parallel mol. dynamics simulations. Simulations demonstrate that H2O diffusion in the direction perpendicular to the clay layers is not negligible and has to be taken into account in the exptl. data anal. A diffusive model with only two fitting parameters D.perp. and D‖ is well adapted for such anal. A clear phys. meaning for the two fitting parameters exists, in view of the geometry of the system. Exptl., the diffusion coeffs. parallel to the clay layers D‖ were estd. to be slowed down by a factor of 5 compared to bulk water. Further, the activation energy of the diffusion process is higher than in bulk water esp. toward the lower temps. within the range studied (20.3 kJ/mol above 300 K increasing to 28.4 kJ/mol below 300 K). Simulations suggest that this is connected to the presence of the cations (1 cation per every 8 water mols.) rather than to the formation of hydrogen bonds between H2O mols. and the clay layers. However, improvements of microscopic force fields are necessary to achieve a full quant. interpretation of the exptl. water diffusion coeffs. We suggest the importance of polarizability in such endeavors.
- 22Paradossi, G.; Cavalieri, F.; Chiessi, E.; Telling, M. T. F. Supercooled Water in PVA Matrixes: I. An Incoherent Quasi-Elastic Neutron Scattering (QENS) Study. J. Phys. Chem. B 2003, 107 (33), 8363– 8371, DOI: 10.1021/jp034542p22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXlt1ygsLg%253D&md5=2479eac6816c5e5c8a7c9dcb7147b76aSupercooled Water in PVA Matrixes: I. An Incoherent Quasi-Elastic Neutron Scattering (QENS) StudyParadossi, Gaio; Cavalieri, Francesca; Chiessi, Ester; Telling, Mark T. F.Journal of Physical Chemistry B (2003), 107 (33), 8363-8371CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)The incoherent quasi-elastic neutron scattering study of poly(vinyl alc.) based hydrogels was carried out to elucidate the dynamic state of water caged in polymeric matrixes with different degree of crosslinking and nature of the crosslinking agent. This investigation focuses on the detn. of the relationship occurring between the diffusional parameters of water and the polymer network architecture. Analyzing the broadening factor of the dynamic structure factor, a marked supercooling of water was detected in all the matrixes under consideration. In all cases, the activation energies were about 4 kcal/mol indicating a hydrogen bond regime governing the matrix-solvent interaction. In some favorable cases, an insight on the polymer dynamics was also possible. The q-dependence of the broadening factor of polymer relaxation component revealed a behavior compatible with a bound random jump dynamics and concerning segmental motions of the chain coupled with the interaction with water.
- 23Abe, H.; Takekiyo, T.; Yoshimura, Y.; Shimizu, A. Static and Dynamic Properties of Nano-Confined Water in Room-Temperature Ionic Liquids. J. Mol. Liq. 2019, 290, 111216, DOI: 10.1016/j.molliq.2019.11121623https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtlaltbrI&md5=f0f5581603272e0ecf28ca0f2e74bfaaStatic and dynamic properties of nano-confined water in room-temperature ionic liquidsAbe, Hiroshi; Takekiyo, Takahiro; Yoshimura, Yukihiro; Shimizu, AkioJournal of Molecular Liquids (2019), 290 (), 111216CODEN: JMLIDT; ISSN:0167-7322. (Elsevier B.V.)A review. Nano-confined water ("water pocket") was spontaneously formed in room-temp. ionic liq. (RTIL). The static structure of the self-dispersed "water pocket" was detd. by a complementary use of small-angle X-ray scattering and small-angle neutron scattering. The size of the "water pocket" is tuned by the water concn. and temp. The "water pocket" suppressed the crystns. both of the RTIL and water at low temp. The solidifications in the intermediate concn. region were quite sensitive to the cooling rate, and non-equil. degree in the mixt. was enhanced by the "water pocket". Hydrogen bonding of water mols. in the "water pocket" was weakened by the nano-confinement. Slow dynamics of the "water pocket" in the RTIL was clarified by quasielastic neutron scattering. The loosely packed and size-tunable "water pocket" is utilized for next generation nano-heterogeneity engineering.
- 24Mamontov, E.; Wesolowski, D. J.; Vlcek, L.; Cummings, P. T.; Rosenqvist, J.; Wang, W.; Cole, D. R. Dynamics of Hydration Water on Rutile Studied by Backscattering Neutron Spectroscopy and Molecular Dynamics Simulation. J. Phys. Chem. C 2008, 112 (32), 12334– 12341, DOI: 10.1021/jp711965x24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXosFKnurg%253D&md5=4ae091ede7d055d800708f25ccc7cd7dDynamics of Hydration Water on Rutile Studied by Backscattering Neutron Spectroscopy and Molecular Dynamics SimulationMamontov, E.; Wesolowski, D. J.; Vlcek, L.; Cummings, P. T.; Rosenqvist, J.; Wang, W.; Cole, D. R.Journal of Physical Chemistry C (2008), 112 (32), 12334-12341CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)The high energy resoln., coupled with the wide dynamic range, of the new backscattering spectrometer (BASIS) at the Spallation Neutron Source, Oak Ridge National Lab., has made it possible to investigate the diffusion dynamics of hydration water on the surface of rutile (TiO2) nanopowder down to a temp. of 195 K. The dynamics measured on the BASIS on the time scale of tens of picoseconds to more than a nanosecond can be attributed to the mobility of the outer hydration water layers. The data obtained on the BASIS and in a previous study using the backscattering and disk-chopper spectrometers at the NIST Center for Neutron Research are coupled with mol. dynamics simulations extended to 50 ns. The results suggest that the scattering expts. probe several types of mol. motion in the surface layers, namely a very fast component that involves dynamics of water mols. with unsatd. hydrogen bonds, a somewhat slower component due to localized motions of all water mols., and a much slower component related to the translational jumps of the fully hydrogen-bonded water mols. The temp. dependence of the relaxation times assocd. with the localized dynamics remains Arrhenius down to at least 195 K, whereas the slow translational component shows non-Arrhenius behavior above about 205 K. Thus, an Arrhenius-type behavior of the faster localized dynamic component extends below the temp. of the dynamic transition in the slow translational component. We suggest that the qual. difference in the character of the temp. dependence between these slow and fast components may be due to the fact that the latter involves motions that require breaking fewer hydrogen bonds.
- 25Jansen, M.; Juranyi, F.; Yarema, O.; Seydel, T.; Wood, V. Ligand Dynamics in Nanocrystal Solids Studied with Quasi-Elastic Neutron Scattering. ACS Nano 2021, 15 (12), 20517– 20526, DOI: 10.1021/acsnano.1c09073There is no corresponding record for this reference.
- 26Seydel, T.; Koza, M. M.; Matsarskaia, O.; André, A.; Maiti, S.; Weber, M.; Schweins, R.; Prévost, S.; Schreiber, F.; Scheele, M. A Neutron Scattering Perspective on the Structure, Softness and Dynamics of the Ligand Shell of PbS Nanocrystals in Solution. Chem. Sci. 2020, 11 (33), 8875– 8884, DOI: 10.1039/D0SC02636K26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsFSlsr7J&md5=abeabbc0a8dd290b2220a9ac3d69a302A neutron scattering perspective on the structure, softness and dynamics of the ligand shell of PbS nanocrystals in solutionSeydel, Tilo; Koza, Michael Marek; Matsarskaia, Olga; Andre, Alexander; Maiti, Santanu; Weber, Michelle; Schweins, Ralf; Prevost, Sylvain; Schreiber, Frank; Scheele, MarcusChemical Science (2020), 11 (33), 8875-8884CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)Small-angle neutron and X-ray scattering, neutron backscattering and neutron time-of-flight spectroscopy are applied to reveal the structure of the ligand shell, the temp.-dependent diffusion properties and the phonon spectrum of PbS nanocrystals functionalized with oleic acid in deuterated hexane. The nanocrystals decorated with oleic acid as well as the desorbed ligand mols. exhibit simple Brownian diffusion with a Stokes-Einstein temp.-dependence and inhibited freezing. Ligand mols. desorbed from the surface show strong spatial confinement. The phonon spectrum of oleic acid adsorbed to the nanocrystal surface exhibits hybrid modes with a predominant Pb-character. Low-energy surface modes of the NCs are prominent and indicate a large mech. softness in soln. This work provides comprehensive insights into the ligand-particle interaction of colloidal nanocrystals in soln. and highlights its effect on the diffusion and vibrational properties as well as their mech. softness.
- 27Sharma, A.; Kruteva, M.; Zamponi, M.; Ehlert, S.; Richter, D.; Förster, S. Quasielastic Neutron Scattering Reveals the Temperature Dependent Rotational Dynamics of Densely Grafted Oleic Acid. J. Chem. Phys. 2022, 156 (16), 164908, DOI: 10.1063/5.0089874There is no corresponding record for this reference.
- 28Sharma, A.; Kruteva, M.; Zamponi, M.; Ehlert, S.; Richter, D.; Förster, S. Influence of Molecular Weight on the Distribution of Segmental Relaxation in Polymer Grafted Nanoparticles. Phys. Rev. Mater. 2022, 6 (1), L012601, DOI: 10.1103/PhysRevMaterials.6.L01260128https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xjt1yru7s%253D&md5=bd60e43bfe29bc86b5690fcbf3540697Influence of molecular weight on the distribution of segmental relaxation in polymer grafted nanoparticlesSharma, Aakash; Kruteva, Margarita; Zamponi, Michaela; Ehlert, Sascha; Richter, Dieter; Foerster, StephanPhysical Review Materials (2022), 6 (1), L012601CODEN: PRMHBS; ISSN:2475-9953. (American Physical Society)The segmental dynamics of one-component nanocomposites (OCNC) is significantly influenced by the mol. wt. (Mw) of the grafted polymer. Neutron backscattering shows that compared to the neat polymer the OCNCs exhibit a shift from slower segmental dynamics at low Mw to faster dynamics at high Mw. We model the local relaxation as distribution of exponential diffusers. This approach reveals the presence of fast and slow segments in both OCNCs. However, their fractional contribution varies with Mw leading to different av. relaxation times. Our results present important insights into the origin of segmental mobility in OCNC and address the inconsistencies in different literature reports.
- 29Jhalaria, M.; Buenning, E.; Huang, Y.; Tyagi, M.; Zorn, R.; Zamponi, M.; García-Sakai, V.; Jestin, J.; Benicewicz, B. C.; Kumar, S. K. Accelerated Local Dynamics in Matrix-Free Polymer Grafted Nanoparticles. Phys. Rev. Lett. 2019, 123, 158003, DOI: 10.1103/PhysRevLett.123.15800329https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXit1ensrjK&md5=160100c0cf6458116ec5c7f56f72dfb6Accelerated Local Dynamics in Matrix-Free Polymer Grafted NanoparticlesJhalaria, Mayank; Buenning, Eileen; Huang, Yucheng; Tyagi, Madhusudan; Zorn, Reiner; Zamponi, Michaela; Garcia-Sakai, Victoria; Jestin, Jacques; Benicewicz, Brian C.; Kumar, Sanat K.Physical Review Letters (2019), 123 (15), 158003CODEN: PRLTAO; ISSN:1079-7114. (American Physical Society)The tracer diffusion coeff. of six different permanent gases in polymer-grafted nanoparticle (GNP) membranes, i.e., neat GNP constructs with no solvent, show a max. as a function of the grafted chain length at fixed grafting d. This trend is reproduced for two different NP sizes and three different polymer chemistries. We postulate that nonmonotonic changes in local, segmental friction as a function of graft chain length (at fixed grafting d.) must underpin these effects, and use quasielastic neutron scattering to probe the self-motions of polymer chains at the relevant segmental scale (i.e., sampling local friction or viscosity). These data, when interpreted with a jump diffusion model, show that, in addn. to the speeding-up in local chain dynamics, the elementary distance over which segments hop is strongly dependent on graft chain length. We therefore conclude that transport modifications in these GNP layers, which are underpinned by a structural transition from a concd. brush to semidilute polymer brush, are a consequence of both spatial and temporal changes, both of which are likely driven by the lower polymer densities of the GNPs relative to the neat polymer.
- 30Pradeep, T.; Mitra, S.; Nair, A. S.; Mukhopadhyay, R. Dynamics of Alkyl Chains in Monolayer-Protected Au and Ag Clusters and Silver Thiolates: A Comprehensive Quasielastic Neutron Scattering Investigation. J. Phys. Chem. B 2004, 108 (22), 7012– 7020, DOI: 10.1021/jp036995030https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXjs1SjsLY%253D&md5=2e5fb16af1b076c70c056173b1f5f909Dynamics of Alkyl Chains in Monolayer-Protected Au and Ag Clusters and Silver Thiolates: A Comprehensive Quasielastic Neutron Scattering InvestigationPradeep, T.; Mitra, S.; Nair, A. Sreekumaran; Mukhopadhyay, R.Journal of Physical Chemistry B (2004), 108 (22), 7012-7020CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)Temp.-dependent dynamics of monolayer-protected Au and Ag nanoclusters and silver thiolates have been investigated with quasielastic neutron scattering. The simplest motion in these systems is the uniaxial rotation of the chain, which evolves slowly with temp. While longer chain monolayers (above C8) on Au clusters are rotationally frozen at room temp., dynamic freedom exists in lower chain lengths. In the superlattice solids of Ag clusters, the dynamics evolve slowly, and at superlattice melting, all the chains are dynamic. The data are consistent with a structure in which the monolayers form bundles on the planes of metal clusters and such bundles interdigitate, forming the cluster assemblies. In thiolates, the dynamics is distinctly different in long- and short-chain systems. It arises abruptly at the melting temp. in C12 but a bit sluggishly in C18, whereas in C6 and C8, it evolves with temp. The data are correlated with temp.-dependent IR spectroscopy, which preserves some of the progression bands even after the bulk melting temp., but loses them completely above 498 K, suggesting a possible partially ordered phase in this temp. window. Our studies have established the fact that (a) no rotational freedom exists in several of the alkyl chain monolayers on metal cluster solids at room temp., (b) simple uniaxial rotation explains the dynamics of these systems, (c) the dynamics evolves slowly, and (d) such motions arise abruptly in long-chain layered thiolates which are similar to planar thiolates. We find that longer chains can possess conformational defects at higher temps., which slow the rotational dynamics.
- 31Bailey, E. J.; Winey, K. I. Dynamics of Polymer Segments, Polymer Chains, and Nanoparticles in Polymer Nanocomposite Melts: A Review. Prog. Polym. Sci. 2020, 105, 101242, DOI: 10.1016/j.progpolymsci.2020.10124231https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXps1yjsro%253D&md5=60f2d9f57cac719bb448aef2d4e85036Dynamics of polymer segments, polymer chains, and nanoparticles in polymer nanocomposite melts: A reviewBailey, Eric J.; Winey, Karen I.Progress in Polymer Science (2020), 105 (), 101242CODEN: PRPSB8; ISSN:0079-6700. (Elsevier Ltd.)A review. The addn. of nanoparticles to a polymer matrix, forming a polymer nanocomposite (PNC), is known to alter the microscopic dynamic processes of both species which leads to unique macroscopic material properties of the PNC. Because the NPs and polymers have overlapping characteristic length, time, and energy scales, the interactions within these materials are complex and the dynamics are interrelated. In this review, we present an overview of exptl., simulation, and theor. results that probe multi-scale polymer and nanoparticle dynamics in polymer nanocomposites and navigate the dense parameter space presented by these multicomponent systems. Although a variety of PNC systems are mentioned, we focus this discussion on linear thermoplastics filled with hard spherical or cylindrical NPs in the melt state. We begin by introducing PNCs, the dynamic processes within them, and the importance of dynamics for properties and processing. At the smallest length and time scales, we discuss segmental dynamics in PNCs, including the role of polymer attributes, NP attributes, and NP-polymer interactions. Then, we present measurements of collective motions and intermediate (Rouse) dynamics in various PNC materials. At longer length and time scales, we discuss polymer center-of-mass diffusion in PNCs with either spherical or anisotropic NPs. Finally, we note some of the remaining challenges in probing dynamics in PNC materials and fundamentally studying PNCs more generally.
- 32Shrestha, S.; Jiang, P.; Sousa, M. H.; Morais, P. C.; Mao, Z.; Gao, C. Citrate-Capped Iron Oxide Nanoparticles Impair the Osteogenic Differentiation Potential of Rat Mesenchymal Stem Cells. J. Mater. Chem. B 2016, 4 (2), 245– 256, DOI: 10.1039/C5TB02007GThere is no corresponding record for this reference.
- 33Milek, T.; Zahn, D. A Surfactants Walk to Work: Modes of Action of Citrate Controlling (10–10) and (000–1) Zinc Oxide Surface Growth from Solution. Z. Anorg. Allg. Chem. 2016, 642 (16), 902– 905, DOI: 10.1002/zaac.201600147There is no corresponding record for this reference.
- 34Klausen, S. N.; Lefmann, K.; Lindgård, P.-A.; Clausen, K. N.; Hansen, M. F.; Bødker, F.; Mørup, S.; Telling, M. An Inelastic Neutron Scattering Study of Hematite Nanoparticles. J. Magn. Magn. Mater. 2003, 266 (1–2), 68– 78, DOI: 10.1016/S0304-8853(03)00457-8There is no corresponding record for this reference.
- 35Gazeau, F.; Dubois, E.; Hennion, M.; Perzynski, R.; Raikher, Y. Quasi-Elastic Neutron Scattering on γ-Fe 2 O 3 Nanoparticles. Europhys. Lett. 1997, 40 (5), 575– 580, DOI: 10.1209/epl/i1997-00507-2There is no corresponding record for this reference.
- 36Eckardt, M.; Thomä, S. L. J.; Dulle, M.; Hörner, G.; Weber, B.; Förster, S.; Zobel, M. Long-Term Colloidally Stable Aqueous Dispersions of ≤ 5 Nm Spinel Ferrite Nanoparticles. ChemistryOpen 2020, 9 (11), 1214– 1220, DOI: 10.1002/open.202000313There is no corresponding record for this reference.
- 37Thomä, S. L. J.; Krauss, S. W.; Eckardt, M.; Chater, P.; Zobel, M. Atomic Insight into Hydration Shells around Facetted Nanoparticles. Nat. Commun. 2019, 10 (1), 995, DOI: 10.1038/s41467-019-09007-137https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB3cfpsFSksw%253D%253D&md5=ee580d9f332e3f6b30c8c50c030b1cf7Atomic insight into hydration shells around facetted nanoparticlesThoma Sabrina L J; Krauss Sebastian W; Eckardt Mirco; Zobel Mirijam; Chater PhilNature communications (2019), 10 (1), 995 ISSN:.Nanoparticles in solution interact with their surroundings via hydration shells. Although the structure of these shells is used to explain nanoscopic properties, experimental structural insight is still missing. Here we show how to access the hydration shell structures around colloidal nanoparticles in scattering experiments. For this, we synthesize variably functionalized magnetic iron oxide nanoparticle dispersions. Irrespective of the capping agent, we identify three distinct interatomic distances within 2.5 ÅA from the particle surface which belong to dissociatively and molecularly adsorbed water molecules, based on theoretical predictions. A weaker restructured hydration shell extends up to 15 ÅA. Our results show that the crystal structure dictates the hydration shell structure. Surprisingly, facets of 7 and 15 nm particles behave like planar surfaces. These findings bridge the large gap between spectroscopic studies on hydrogen bond networks and theoretical advances in solvation science.
- 38Zobel, M.; Appel, M. Water Dynamics on Iron Oxide Nanoparticles; Institut Laue-Langevin Database, 2020. DOI: 10.5291/ILL-DATA.EASY-636 .There is no corresponding record for this reference.
- 39Zobel, M.; Appel, M.; Feghelm, A.; Magerl, A.; Thomae, S. Diffusion Dynamics of Water and Citrate Molecules on the Surface of Iron Oxide Nanoparticles; Institut Laue-Langevin Database, 2021. DOI: 10.5291/ILL-DATA.9-12-648 .There is no corresponding record for this reference.
- 40Appel, M.; Frick, B.; Magerl, A. First Results with the Neutron Backscattering and TOF Spectrometer Option BATS on IN16B. Phys. B: Condens. Matter 2019, 562, 6– 8, DOI: 10.1016/j.physb.2018.11.06240https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXkvVCht78%253D&md5=15b0809533464f7319ae32db703058b1First results with the neutron backscattering and TOF spectrometer option BATS on IN16BAppel, Markus; Frick, Bernhard; Magerl, AndreasPhysica B: Condensed Matter (Amsterdam, Netherlands) (2019), 562 (), 6-8CODEN: PHYBE3; ISSN:0921-4526. (Elsevier B.V.)We report on the status of the ongoing upgrade of the neutron backscattering spectrometer IN16B with the new BATS option, which enables operation of the instrument in inverted Time-of-Flight mode. First commissioning results are available, confirming the expectations and demonstrating its capabilities. Using Si 111 analyzers, BATS allows to record neutron spectra with variable energy resoln. down to 1.5 μeV with momentum transfers up to 1.9 Å-1, reaching energy transfers beyond -600 μeV and achieving a signal to noise ratio above 104.
- 41Zobel, M.; Appel, M.; Magerl, A.; Thomae, S. Diffusion in the Liquid Interface Region of IONPs; Institut Laue-Langevin Database, 2021. DOI: 10.5291/ILL-DATA.INTER-528 .There is no corresponding record for this reference.
- 42Arnold, O.; Bilheux, J. C.; Borreguero, J. M.; Buts, A.; Campbell, S. I.; Chapon, L.; Doucet, M.; Draper, N.; Ferraz Leal, R.; Gigg, M. A. Mantid─Data Analysis and Visualization Package for Neutron Scattering and SR Experiments. Nucl. Instrum. Methods Phys. Res., Sect. A 2014, 764, 156– 166, DOI: 10.1016/j.nima.2014.07.02942https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtlGntrfL&md5=9a34bb9e366fca0e39091a5c4016ccd7Mantid-Data analysis and visualization package for neutron scattering and μ SR experimentsArnold, O.; Bilheux, J. C.; Borreguero, J. M.; Buts, A.; Campbell, S. I.; Chapon, L.; Doucet, M.; Draper, N.; Ferraz Leal, R.; Gigg, M. A.; Lynch, V. E.; Markvardsen, A.; Mikkelson, D. J.; Mikkelson, R. L.; Miller, R.; Palmen, K.; Parker, P.; Passos, G.; Perring, T. G.; Peterson, P. F.; Ren, S.; Reuter, M. A.; Savici, A. T.; Taylor, J. W.; Taylor, R. J.; Tolchenov, R.; Zhou, W.; Zikovsky, J.Nuclear Instruments & Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment (2014), 764 (), 156-166CODEN: NIMAER; ISSN:0168-9002. (Elsevier B.V.)The Mantid framework is a software soln. developed for the anal. and visualization of neutron scattering and muon spin measurements. The framework is jointly developed by software engineers and scientists at the ISIS Neutron and Muon Facility and the Oak Ridge National Lab. The objectives, functionality and novel design aspects of Mantid are described.
- 43Studer, A. J.; Hagen, M. E.; Noakes, T. J. Wombat: The High-Intensity Powder Diffractometer at the OPAL Reactor. Phys. B: Condens. Matter 2006, 385–386, 1013– 1015, DOI: 10.1016/j.physb.2006.05.32343https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28Xht1CitLvE&md5=f0b3d824628269df296550f430abeff0Wombat: The high-intensity powder diffractometer at the OPAL reactorStuder, Andrew J.; Hagen, Mark E.; Noakes, Terrence J.Physica B: Condensed Matter (Amsterdam, Netherlands) (2006), 385-386 (Pt. 2), 1013-1015CODEN: PHYBE3; ISSN:0921-4526. (Elsevier B.V.)The Wombat powder diffractometer will be located on the TG1 thermal guide at the OPAL reactor. A variable vertically focusing monochromator will provide a flux of up to ≈108 ns-1 cm-2 at the sample position. A compact curved 2-dimensional position sensitive detector will allow simultaneous acquisition of 120° in 2θ, with ≈106 s-1 count rate capability and time resoln. down to the microsecond level. Wombat is designed for expts. requiring rapid real time acquisition (time-resolved environmental or kinetics expts.) or very good signal to noise (expts. with difficult sample environments or small sample vols.).
- 44Toby, B. H.; Von Dreele, R. B. GSAS-II: the genesis of a modern open-source all purpose crystallography software package. J. Appl. Crystallogr. 2013, 46 (2), 544– 549, DOI: 10.1107/S002188981300353144https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjvFWnu7c%253D&md5=48a7dcdb1d1f10d6f9d7fe3e746d58fdGSAS-II: the genesis of a modern open-source all purpose crystallography software packageToby, Brian H.; Von Dreele, Robert B.Journal of Applied Crystallography (2013), 46 (2), 544-549CODEN: JACGAR; ISSN:0021-8898. (International Union of Crystallography)The newly developed GSAS-II software is a general purpose package for data redn., structure soln. and structure refinement that can be used with both single-crystal and powder diffraction data from both neutron and x-ray sources, including lab. and synchrotron sources, collected on both two- and 1-dimensional detectors. It is intended that GSAS-II will eventually replace both the GSAS and the EXPGUI packages, as well as many other utilities. GSAS-II is open source and is written largely in object-oriented Python but offers speeds comparable to compiled code because of its reliance on the Python NumPy and SciPy packages for computation. It runs on all common computer platforms and offers highly integrated graphics, both for a user interface and for interpretation of parameters. The package can be applied to all stages of crystallog. anal. for const.-wavelength x-ray and neutron data. Plans for considerable addnl. development are discussed.
- 45Perez-Mato, J. M.; Gallego, S. V.; Tasci, E. S.; Elcoro, L.; de la Flor, G.; Aroyo, M. I. Symmetry-Based Computational Tools for Magnetic Crystallography. Annu. Rev. Mater. Res. 2015, 45 (1), 217– 248, DOI: 10.1146/annurev-matsci-070214-02100845https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFWqurvM&md5=210c550fb8617fc74460b8e891df6a5eSymmetry-Based Computational Tools for Magnetic CrystallographyPerez-Mato, J. M.; Gallego, S. V.; Tasci, E. S.; Elcoro, L.; de la Flor, G.; Aroyo, M. I.Annual Review of Materials Research (2015), 45 (), 217-248CODEN: ARMRCU; ISSN:1531-7331. (Annual Reviews)In recent years, two important advances have opened new doors for the characterization and detn. of magnetic structures. Firstly, researchers have produced computer-readable listings of the magnetic or Shubnikov space groups. Secondly, they have extended and applied the superspace formalism, which is presently the std. approach for the description of nonmagnetic incommensurate structures and their symmetry, to magnetic structures. These breakthroughs have been the basis for the subsequent development of a series of computer tools that allow a more efficient and comprehensive application of magnetic symmetry, both commensurate and incommensurate. Here we briefly review the capabilities of these computation instruments and present the fundamental concepts on which they are based, providing various examples. We show how these tools facilitate the use of symmetry arguments expressed as either a magnetic space group or a magnetic superspace group and allow the exploration of the possible magnetic orderings assocd. with one or more propagation vectors in a form that complements and goes beyond the traditional representation method. Special focus is placed on the programs available online at the Bilbao Crystallog. Server (http://www.cryst.ehu.es).
- 46Sabrina, L. J. Thomä; Mirijam Zobel. Ethanol-Water Motifs - a Re-Interpretation of the Double-Difference Pair Distribution Functions of Aqueous Iron Oxide Nanoparticle Dispersions. J. Chem. Phys. 2024, 158 (22), 224704, DOI: 10.1063/5.0147659There is no corresponding record for this reference.
- 47Petkov, V.; Cozzoli, P. D.; Buonsanti, R.; Cingolani, R.; Ren, Y. Size, Shape, and Internal Atomic Ordering of Nanocrystals by Atomic Pair Distribution Functions: A Comparative Study of γ-Fe2O3 Nanosized Spheres and Tetrapods. J. Am. Chem. Soc. 2009, 131 (40), 14264– 14266, DOI: 10.1021/ja906758947https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhtFKkt7jP&md5=34e2cef6d9ec060ed3ad22638d7882d2Size, Shape, and Internal Atomic Ordering of Nanocrystals by Atomic Pair Distribution Functions: A Comparative Study of γ-Fe2O3 Nanosized Spheres and TetrapodsPetkov, Valeri; Cozzoli, P. Davide; Buonsanti, Raffaella; Cingolani, Roberto; Ren, YangJournal of the American Chemical Society (2009), 131 (40), 14264-14266CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Due to their limited length of structural coherence nanocryst. materials show very diffuse powder x-ray diffraction patterns that are difficult to interpret unambiguously. A combination of high-energy x-ray powder diffraction and at. pair distribution function anal. can be used to both assess the geometry (i.e., size and shape) and det. the internal at. ordering of nanocryst. materials in a straightforward way. As an example cubic γ-Fe2O3 nanosized crystals shaped as spheres and tetrapods are considered.
- 48Shmakov, A. N.; Kryukova, G. N.; Tsybulya, S. V.; Chuvilin, A. L.; Solovyeva, L. P. Vacancy Ordering in γ-Fe2O3: Synchrotron X-Ray Powder Diffraction and High-Resolution Electron Microscopy Studies. J. Appl. Crystallogr. 1995, 28 (2), 141– 145, DOI: 10.1107/S0021889894010113There is no corresponding record for this reference.
- 49Girardet, T.; Venturini, P.; Martinez, H.; Dupin, J.-C.; Cleymand, F.; Fleutot, S. Spinel Magnetic Iron Oxide Nanoparticles: Properties, Synthesis and Washing Methods. Appl. Sci. 2022, 12 (16), 8127, DOI: 10.3390/app12168127There is no corresponding record for this reference.
- 50Bixner, O.; Lassenberger, A.; Baurecht, D.; Reimhult, E. Complete Exchange of the Hydrophobic Dispersant Shell on Monodisperse Superparamagnetic Iron Oxide Nanoparticles. Langmuir 2015, 31 (33), 9198– 9204, DOI: 10.1021/acs.langmuir.5b0183350https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXht1Knu7fK&md5=f1e29e2ad1a731259f6cf1eaa572a68fComplete Exchange of the Hydrophobic Dispersant Shell on Monodisperse Superparamagnetic Iron Oxide NanoparticlesBixner, Oliver; Lassenberger, Andrea; Baurecht, Dieter; Reimhult, ErikLangmuir (2015), 31 (33), 9198-9204CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)High-temp. synthesized monodisperse superparamagnetic iron oxide nanoparticles are obtained with a strongly bound ligand shell of oleic acid and its decompn. products. Most applications require a stable presentation of a defined surface chem.; therefore, the native shell has to be completely exchanged for dispersants with irreversible affinity to the nanoparticle surface. Attenuated total reflectance IR spectra and thermogravimetric anal./differential scanning calorimetry were used to evaluate the limitations of commonly used approaches. A mechanism and multiple exchange scheme that attains the goal of complete and irreversible ligand replacement on monodisperse nanoparticles of various sizes is presented. The obtained hydrophobic nanoparticles are ideally suited for magnetically controlled drug delivery and membrane applications and for the investigation of fundamental interfacial properties of ultra small core-shell architectures.
- 51Hill, A. H.; Jacobsen, H.; Stewart, J. R.; Jiao, F.; Jensen, N. P.; Holm, S. L.; Mutka, H.; Seydel, T.; Harrison, A.; Lefmann, K. Magnetic Properties of Nano-Scale Hematite, α-Fe2O3, Studied by Time-of-Flight Inelastic Neutron Spectroscopy. J. Chem. Phys. 2014, 140 (4), 044709, DOI: 10.1063/1.4862235There is no corresponding record for this reference.
- 52Brown, W. F. Thermal Fluctuations of a Single-Domain Particle. Phys. Rev. 1963, 130 (5), 1677– 1686, DOI: 10.1103/PhysRev.130.1677There is no corresponding record for this reference.
- 53Situm, A.; Rahman, M. A.; Goldberg, S.; Al-Abadleh, H. A. Spectral Characterization and Surface Complexation Modeling of Low Molecular Weight Organics on Hematite Nanoparticles: Role of Electrolytes in the Binding Mechanism. Environ. Sci. Nano 2016, 3 (4), 910– 926, DOI: 10.1039/C6EN00132G53https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtFanu7rJ&md5=e91af54a581246f69c549ae660b1793fSpectral characterization and surface complexation modeling of low molecular weight organics on hematite nanoparticles: role of electrolytes in the binding mechanismSitum, Arthur; Rahman, Mohammad A.; Goldberg, Sabine; Al-Abadleh, Hind A.Environmental Science: Nano (2016), 3 (4), 910-926CODEN: ESNNA4; ISSN:2051-8161. (Royal Society of Chemistry)Given the ubiquity of org.-metal oxide interfaces in environmental and medical systems, it is necessary to obtain mechanistic details at the mol. level from exptl. procedures that mimic real systems and conditions. We report herein the adsorption pH envelopes (range 9-5) isotherms at pH 7. These studies showed that the structure of the org. species influences the type and relative amts. of inner- vs. outer-sphere surface complexes. This has consequences on the surface charge as shown from electrolyte concn.-dependent studies. Example, citrate forms a mix of protonated monodentate inner-sphere complexes with one neg. charge and deprotonated outer-sphere complexes with net two neg. charges. Oxalate forms mostly doubly deprotonated outer-sphere complexes with inaccessible neighboring sites with contributions from deprotonated inner-sphere complexes. Lastly, pyrocatechol forms mostly bidentate inner-sphere complexes. Layering of interfacial electrolyte ions from KCl, NaCl and KBr, used to adjust the electrolyte concn., caused an overall enhancement in the amt. of adsorbed weakly-bonded citrate and oxalate. Also, hematite nanoparticles retain more adsorbed citrate and pyrocatechol than adsorbed oxalate when chloride or bromide was flowed as a neg.-charged weak desorbing agent at pH 7. These results have implications for the overall surface chem. of hematite nanoparticles in the presence of org. matter, particularly those contg. carboxylate and phenolate functional groups.
- 54Yeasmin, S.; Singh, B.; Kookana, R. S.; Farrell, M.; Sparks, D. L.; Johnston, C. T. Influence of Mineral Characteristics on the Retention of Low Molecular Weight Organic Compounds: A Batch Sorption-Desorption and ATR-FTIR Study. J. Colloid Interface Sci. 2014, 432, 246– 257, DOI: 10.1016/j.jcis.2014.06.03654https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1KgsLzF&md5=92fa8e5902c23052761dd5d856839544Influence of mineral characteristics on the retention of low molecular weight organic compounds: A batch sorption-desorption and ATR-FTIR studyYeasmin, Sabina; Singh, Balwant; Kookana, Rai S.; Farrell, Mark; Sparks, Donald L.; Johnston, Cliff T.Journal of Colloid and Interface Science (2014), 432 (), 246-257CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)Batch expts. were conducted to evaluate the sorption-desorption behavior of 14C-labeled carboxylic acids (citric and oxalic) and amino acids (glutamic, alanine, phenylalanine and lysine) on pure minerals (kaolinite, illite, montmorillonite, ferrihydrite and goethite). The sorption expts. were complemented by ATR-FTIR spectroscopy to gain possible mechanistic insight into the org. acids-mineral interactions. In terms of charge, the org. solutes ranged from strongly neg. (i.e., citric) to pos. charged solutes (i.e., lysine); similarly the mineral phases also ranged from pos. to neg. charged surfaces. In general, sorption of anionic carboxylic and glutamic acids was higher compared to the other compds. (except lysine). Cationic lysine showed a stronger affinity to permanently charged phyllosilicates than Fe oxides. The sorption of alanine and phenylalanine was consistently low for all minerals, with relatively higher sorption and lower desorption of phenylalanine than alanine. Overall, the role of carboxylic functional groups for the sorption and retention of these carboxylic and amino acids on Fe oxides (and kaolinite) and of amino group on 2:1 phyllosilicates was noticeable. Mineral properties (surface chem., sp. surface area), chem. of the org. compds. (pKa value, functional groups) and the equil. pH of the system together controlled the differences in sorption-desorption patterns. The results of this study aid to understand the effects of mineralogical and chem. factors that affect naturally occurring low mol. wt. org. compds. sorption under field conditions.
- 55Assis, M. B. d. S.; Werneck, I. H. S. R.; de Moraes, G. N.; Semaan, F. S.; Pacheco Pereira, R. Citrate-Capped Iron Oxide Nanoparticles: Ultrasound-Assisted Synthesis, Structure and Thermal Properties. Mater. Res. Express 2019, 6 (4), 045064, DOI: 10.1088/2053-1591/aaff2aThere is no corresponding record for this reference.
- 56Mamontov, E.; Vlcek, L.; Wesolowski, D. J.; Cummings, P. T.; Wang, W.; Anovitz, L. M.; Rosenqvist, J.; Brown, C. M.; Garcia Sakai, V. Dynamics and Structure of Hydration Water on Rutile and Cassiterite Nanopowders Studied by Quasielastic Neutron Scattering and Molecular Dynamics Simulations. J. Phys. Chem. C 2007, 111 (11), 4328– 4341, DOI: 10.1021/jp067242r56https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXitFKrtrs%253D&md5=bf6be7109e624e16c8f1e76a8a9994e8Dynamics and Structure of Hydration Water on Rutile and Cassiterite Nanopowders Studied by Quasielastic Neutron Scattering and Molecular Dynamics SimulationsMamontov, E.; Vlcek, L.; Wesolowski, D. J.; Cummings, P. T.; Wang, W.; Anovitz, L. M.; Rosenqvist, J.; Brown, C. M.; Garcia Sakai, V.Journal of Physical Chemistry C (2007), 111 (11), 4328-4341CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Quasielastic neutron scattering (QENS) expts. carried out using time-of-flight and backscattering neutron spectrometers with widely different energy resoln. and dynamic range revealed the diffusion dynamics of hydration H2O in nanopowder rutile (TiO2) and cassiterite (SnO2) that possess the rutile crystal structure with the (110) crystal face predominant on the surface. These isostructural oxides differ in their bulk dielec. consts., metal atom electronegativities, and lattice spacings, which may all contribute to differences in the structure and dynamics of sorbed H2O. When hydrated under ambient conditions, the nanopowders had similar levels of hydration: ∼3.5 (OH/H2O) mols. per Ti2O4 surface structural unit of TiO2 and ∼4.0 (OH/H2O) mols. per Sn2O4 surface unit of SnO2. Ab initio optimized classical mol. dynamics (MD) simulations of the (110) surfaces in contact with SPC/E H2O at these levels of hydration indicate 3 structurally distinct sorbed H2O layers L1, L2, and L3, where the L1 species are either assocd. H2O mols. or dissocd. hydroxyl groups in direct contact with the surface, L2 H2O mols. are hydrogen bonded to L1 and structural oxygen atoms at the surface, and L3 H2O mols. are more weakly bound. At the hydration levels studied, L3 is incomplete compared with axial oxygen d. profiles of bulk SPC/E H2O in contact with these surfaces, but the structure and dynamics of L1-L3 species are remarkably similar at full and reduced H2O coverage. Three hydration H2O diffusion components, on the time scale of a picosecond, tens of picoseconds, and a nanosecond could be extd. from the QENS spectra of both oxides. However, the spectral wt. of the faster components was significantly lower for SnO2 compared to TiO2. In TiO2 hydration H2O, the more strongly bound L2 H2O mols. exhibited slow (on the time scale of a nanosecond) dynamics characterized by super-Arrhenius, fragile behavior >220 K and the dynamic transition to Arrhenius, strong behavior at lower temps. The more loosely bound L3 H2O mols. in TiO2 exhibited faster dynamics with Arrhenius temp. dependence. However, the slow diffusion component in L2 hydration H2O on SnO2, also on the time scale of a nanosecond, showed little evidence of super-Arrhenius behavior or the fragile-to-strong transition. The occurrence of super-Arrhenius dynamic behavior in surface H2O is sensitive to the strength of interaction of the H2O mols. with the surface and the distribution of surface H2O mols. among the different hydration layers. Anal. of energy transfer spectra generated from the mol. dynamics simulations shows fast and intermediate dynamics in good agreement with the QENS time-of-flight results. Also demonstrated by the simulation is the fast (compared to 1 ns) exchange between the H2O mols. of the L2 and L3 hydration layers.
- 57Jørgensen, J. E.; Mosegaard, L.; Thomsen, L. E.; Jensen, T. R.; Hanson, J. C. Formation of γ-Fe2O3 Nanoparticles and Vacancy Ordering: An in Situ X-Ray Powder Diffraction Study. J. Solid State Chem. 2007, 180 (1), 180– 185, DOI: 10.1016/j.jssc.2006.09.03357https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXnt1Cisg%253D%253D&md5=dd741a3e27683eaeda044a7480f7d17dFormation of γ-Fe2O3 nanoparticles and vacancy ordering: An in situ X-ray powder diffraction studyJorgensen, Jens-Erik; Mosegaard, Lene; Thomsen, Line E.; Jensen, Torben R.; Hanson, Jonathan C.Journal of Solid State Chemistry (2007), 180 (1), 180-185CODEN: JSSCBI; ISSN:0022-4596. (Elsevier)The formation of maghemite, γ-Fe2O3 nanoparticles was studied by in situ x-ray powder diffraction. The maghemite was formed by thermal decompn. of an amorphous precursor compd. made by reacting lauric acid, CH3(CH2)10COOH with Fe(NO3)3·9H2O. Cubic γ-Fe2O3 was formed directly from the amorphous precursor and vacancy ordering starts ∼45 min later at 305° resulting in a tripled unit cell along the c-axis. The kinetics of grain growth was found to obey a power law with growth exponents n equal to 0.136(6) and 0.103(5) at 305 and 340°, resp. Particles with av. sizes of 12 and 13 nm were obtained in 86 and 76 min at 305 and 340°, resp. The structure of cubic and vacancy ordered phases of γ-Fe2O3 was studied at 305° by Rietveld refinements.
- 58Köhler, T.; Feoktystov, A.; Petracic, O.; Kentzinger, E.; Bhatnagar-Schöffmann, T.; Feygenson, M.; Nandakumaran, N.; Landers, J.; Wende, H.; Cervellino, A. Mechanism of Magnetization Reduction in Iron Oxide Nanoparticles. Nanoscale 2021, 13 (14), 6965– 6976, DOI: 10.1039/D0NR08615KThere is no corresponding record for this reference.
- 59Sinha, S. K.; Sirota, E. B.; Garoff, S.; Stanley, H. B. X-Ray and Neutron Scattering from Rough Surfaces. Phys. Rev. B 1988, 38 (4), 2297– 2311, DOI: 10.1103/PhysRevB.38.229759https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2sfhtlejtQ%253D%253D&md5=6e8b80c49359bb2646efe482e4f14c34X-ray and neutron scattering from rough surfacesSinha; Sirota; Garoff; StanleyPhysical review. B, Condensed matter (1988), 38 (4), 2297-2311 ISSN:0163-1829.There is no expanded citation for this reference.
- 60Grapengeter, H. H.; Alefeld, B.; Kosfeld, R. An Investigation of Micro-Brownian Motions in Polydimethylsiloxane by Complementary Incoherent-Neutron-Scattering and Nuclear-Magnetic-Resonance Experiments below Room Temperature. Colloid Polym. Sci. 1987, 265, 226– 233, DOI: 10.1007/bf0141271160https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2sXhslOitLg%253D&md5=570054fa5d4021d5ff81dfb3d0f9a029An investigation of micro-Brownian motion in poly(dimethylsiloxane) by complementary incoherent neutron scattering and nuclear magnetic resonance experiments below room temperatureGrapengeter, H. H.; Alefeld, B.; Kosfeld, R.Colloid and Polymer Science (1987), 265 (3), 226-33CODEN: CPMSB6; ISSN:0303-402X.The random segmental rotational jump motions of Me groups in di-Me siloxane (mol. wt. 1.32 × 105) were studied by the 2 title techniques. Magnetic relaxation and line width expts. were complementary to incoherent neutron scattering fixed-window expts.; the principle of the fixed-window expts. was discussed in detail. Satisfactory agreement of these exptl. techniques was achieved in the detn. of the 2 model parameters of the motional processes in question, i.e. the activation energy and the preexponential factor of the Arrhenius relation made for the correlation time or jump time, resp.
- 61Mamontov, E.; Smith, R. W.; Billings, J. J.; Ramirez-Cuesta, A. J. Simple Analytical Model for Fitting QENS Data from Liquids. Phys. B: Condens. Matter 2019, 566, 50– 54, DOI: 10.1016/j.physb.2019.01.051There is no corresponding record for this reference.
- 62Krynicki, K.; Green, C. D.; Sawyer, D. W. Pressure and Temperature Dependence of Self-Diffusion in Water. Faraday Discuss. Chem. Soc. 1978, 66, 199, DOI: 10.1039/dc978660019962https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL3cXivVOisw%253D%253D&md5=09a108d79ddcb120ba31840466f2633bPressure and temperature dependence of self-diffusion in waterKrynicki, Kazimierz; Green, Christopher D.; Sawyer, David W.Faraday Discussions of the Chemical Society (1978), 66 (Struct. Motion Mol. Liq.), 199-208CODEN: FDCSB7; ISSN:0301-7249.The self-diffusion coeff. (D) for pure liq. H2O was detd. at 275.2-498.2 K and ≤1.75 kbar by the proton spin echo method. Values of D agree with available published results. The results were discussed in terms of several theories. The Stokes-Einstein relation is obeyed in the slipping boundary limit. The cubic cell model of G. Houghton (1964) accounts satisfactorily for the exptl. D values, particularly at higher temps. A modified hard-sphere theory is more satisfactory than the simple hard-sphere theory esp. at low temps. An activation anal. at const. d. shows that H2O behaves very differently from nonassocd. liqs., and suggests that an increase in both temp. and pressure leads to an increase in the fraction of free unbonded H2O mols. A free-vol. anal. leads to a modified Arrhenius equation which involves pressure-dependent terms. The semiempirical equation describes the results within exptl. error and predicts a glass temp. at 115 K which is in reasonable agreement with values obtained by other method.
- 63Bée, M. Quasielastic Neutron Scattering; Adam Hilger, 1988.There is no corresponding record for this reference.
Supporting Information
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.jpcc.4c00479.
Sample characterization, detector bank numbers and corresponding Q values, neutron powder diffraction, model equations, logarithmic-scale QENS plots, and magnetic relaxation (PDF)
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