We demonstrate the synthesis of perovskite oxide SrTiO₃ with ideal cation stoichiometry and homogeneous La doping using air-stable Sr–Ti and La–Ti bimetallic peroxo complexes with a 1:1 cation ratio. Phase-pure SrTiO₃, La₂Ti₂O₇, and LaTiO₃ were successfully synthesized by thermal decomposition of those complexes. La-doped SrTiO₃ was obtained by mixing the Sr–Ti and La–Ti complexes in an acid solution, followed by thermal decomposition. La-doped SrTiO₃ showed systematic chemical trends in the lattice constant and electrical conduction. Not only those bulk polycrystals but also cation-stoichiometric SrTiO₃ epitaxial thin films were grown with an atomically flat surface from the Sr–Ti complex.

A doubly N-confused hexaphyrin dinuclear cobalt complex (Co₂DNCH) is revealed as an efficient water oxidation catalyst, outperforming the mononuclear cobalt porphyrin with the same aryl group as those in Co₂DNCH. By photoirradiation of a water/acetone-d₆ (9:1) mixture containing Co₂DNCH, [Ru^II(bpy)₃]²⁺, and S₂O₈^2– as the water oxidation catalyst, photosensitizer, and sacrificial electron acceptor, respectively, with visible light, O₂ was obtained as the maximum with turnover number = 1200, turnover frequency = 3.9 s^–1, and quantum yield = 0.30.

A zinc acetate borate, [ZnAc]·[ZnBO₃] (1), was synthesized under mild conditions; the B@Zn₂O₃ layer of 1 contains a 6-membered ring embedded with a rare BO₃ unit. The layers are pillared by acetate ions to form a 3D framework. The pillared structure of 1 supplies enough space as a nanoreactor, and the related application of CO₂-to-CO reduction has been confirmed.

The generation of elastic crystalline fibers from a nonfibrous crystal of metal complex is demonstrated. Applying mechanical stimuli to a platelike crystal of Ni^II(salophen) [1; H₂salophen = N,N′-bis(salicylidene)-o-phenylenediamine] resulted in this complex being transformed into crystal fibers, which could be bent into a loop and demonstrated its high elasticity. Single-crystal X-ray diffraction analyses revealed that the transformation reflects the presence of molecular strands that are composed of a one-dimensional assembly of the slip-stacked arrangement by nearly planar Ni(salophen) molecules. The fiber flexibility was demonstrated to be lost upon the introduction of chloroform solvent molecules into the crystal lattice by recrystallization.

Luminescent silver(I) coordination polymers having a {Ag₂(μ-X)₂} rhombic core (X = I, Br) were prepared using pyrazine (pyz), methylpyrazine (Mepyz), and aminopyrazine (ampyz) as bridging ligands. Photophysical measurements show that the complexes were strongly luminescent in the solid state at room temperature; further, the emissive excited state of the pyz and Mepyz complexes was a triplet charge-transfer (³CT) excited state, similar to that of their copper(I) congeners, whereas that of the ampyz complex was a intraligand (³IL) excited state. The energy of the ³CT excited state of a silver halogenido complex was revealed to be ca. 5000 cm^–1 higher than that of the corresponding copper complex.

A two-dimensional Ni-heteroatom-based metal–organic framework (MOF) array was directly grown on C paper (Ni-MOF-A/CP) via one-pot solvothermal reaction. According to the strategy for MOF self-assembly on C paper, Ni-MOFs were also synthesized on Ni foam (Ni-MOF/NF) with different sizes and morphologies. The newly resulting MOFs with ternary (Ni, S, and N) active sites exhibited enhanced activity toward oxygen evolution reaction [e.g., Ni-MOF-A/CP: E(5 mA cm^–2) = 333 mV and a low Tafel slope of 80 mV dec^–1].

Herein, we report a highly rare robust 4d–5f bimetal–organic framework that shows high porosity and thermal/chemical stability and thus is capable of removing trace SO₂ from a SO₂/CO₂/N₂ mixture even under humid conditions. This work not only shows a novel adsorbent for SO₂ removal but also extends the function of actinium-based coordination compounds.

New kinds of diradical rare-earth metal complexes supported by diazabutadiene (DAD) ligands, [(DAD)₂LnN(TMS)₂] (1; Ln = Dy, Lu; TMS = SiMe₃), were synthesized and studied. They showed a new [radical–Ln–radical] alignment with distorted square-pyramidal geometry. Structural and density functional theory analysis illustrated the radical anionic nature of the ligands. Magnetic studies revealed antiferromagnetic coupling of the two radicals in 1-Lu. 1-Dy showed typical single-molecule-magnet (SMM) behavior with an effective energy barrier of 231 K, which is much higher than those of similar radical-containing SMMs. Magnetostructural analysis suggests that the anionic [N(TMS)₂]⁻ group plays a vital role in the SMM property. This study provides a new platform for further improving the performance of radical–Ln SMMs.

Fluorescent agents play an important role in the peroxyoxalate chemiluminescence system. However, the effect of different frameworks on chemiluminescence (CL) has not been explored. Herein two pyrene-based metal–organic frameworks (MOFs), [Pb₂L]_n·2nDMA·2nH₂O (1) and [(Ca₂L)·(DMF)₃]_n·2.5nDMF·6nH₂O (2) (H₄L = 5,5′-(-pyrene-1,6-diyl)-diisophthalic acid; DMA = N,N′-dimethylacetamide; DMF = N,N′-dimethylformamide), have been successfully synthesized and are applied to CL. They both exhibit strong and lasting emission that is visible to the naked eye and is significantly stronger than that of the ligand. More importantly, compared with 2, 1 has notably better CL performance. We infer that the reason may be that 1 has higher stability and larger open channels, which can avoid the aggregation of organic ligands as well as provide an effective pathway for the active substance to diffuse into the channels.

Six rhenium(I) κ³N-dicarbonyl complexes with 4′-(4-substituted phenyl)terpyridine ligands were evaluated in their ground and excited states. These complexes, bearing substituents of different electron-donating strengths—from CN to NMe₂—were studied by a combination of transient IR (TRIR), electrochemistry, and IR spectroelectrochemistry, as well as time-dependent density functional theory (TD-DFT). They exhibit panchromatic absorption and can act as stronger photoreductants than their tricarbonyl counterparts. The ground- and excited-state potentials, absorption maxima, and lifetimes (250–750 ps) of these complexes correlate well with the Hammett σ_p substituent constants, showing the systematic effect of remote substitution in the ligand framework. TRIR spectroscopy allowed us to assign the lowest singlet and triplet excited states to a metal-to-ligand charge-transfer (MLCT) character. This result contrasts our previous report on analogous κ²N-tricarbonyl complexes, where remote substitution switched the character from MLCT to intraligand charge transfer. With the help of TD-DFT calculations, we dissect the geometric and electronic effects of coordination of the third pyridine, local symmetries, and increasing conjugation length. These results give valuable insights for the design of complexes with long-lived triplet excited states and enhanced absorption throughout the visible spectrum, while showcasing the boundaries of the excited-state switching strategy via remote substitution.

The ground- and excited-state properties of six rhenium(I) κ²N-tricarbonyl complexes with 4′-(4-substituted-phenyl)terpyridine ligands bearing substituents of different electron-donating abilities were evaluated. Significant modulation of the electrochemical potentials and a nearly 4-fold variation of the triplet metal-to-ligand charge-transfer (³MLCT) lifetimes were observed upon going from CN to OMe. With the more electron-donating NMe₂ group, we observed in the κ²N complex the appearance of a very strong absorption band, red-shifted by ca. 100 nm with respect to the other complexes. This was accompanied by a dramatic enhancement of the excited-state lifetime (380 vs 1.5 ns), and a character change from ³MLCT to intraligand charge transfer (³ILCT), despite the remote location of the substituent. The dynamics and character of the excited states of all complexes were assigned by combining transient IR spectroscopy, IR spectroelectrochemistry, and (time-dependent) density functional theory calculations. Selected complexes were evaluated as photosensitizers for hydrogen production, with the κ²N-NMe₂ complex resulting in a stable and efficient photocatalytic system reaching TON_Re values of over 2100, representing the first application of the ³ILCT state of a rhenium(I) carbonyl complex in a stable photocatalytic system.

Systematic substituent variations on amidinate ligands bring delicate changes of CrN₄ coordination in a family of chromium(II) complexes with the common formula of Cr(RNC(CH₃)NR)₂, where R = iPr (1), Cy (2), Dipp (Dipp = 2, 6-diisopropylphenyl) (3), and tBu (4). With the largest substituent group, 4 shows the largest distortion of the N₄ coordination geometry from square-planar to seesaw shape, which leads to its field-induced single-molecule magnet (SMM) behavior. This is an indication that 4 has the strongest axial magnetic anisotropy and/or optimized magnetic relaxation process. Combined with high-frequency/field electron paramagnetic resonance (HF-EPR) experiments and ab initio calculations, we deduce that the smallest energy gap between ground ⁴Ψ₀ and the first excited ⁴Ψ₁ orbitals in 4 contributes the most to its strongest magnetic anisotropy. Moreover, the lower E value of 4 ensures its being a field-induced SMM. Specifically, the D and E values were found to be correlated to the dihedral angle between the ΔN₁CrN₂ and ΔN₃CrN₄ triangles, indicating that distortion from ideal square-planar geometry to the seesaw help increase axial magnetic anisotropy and suppress the transversal part. Thus, the study on this system not only expands the family of Cr(II)-based SMMs but also contributes to a deeper understanding of magneto-structural correlation in four-coordinate Cr(II) SMMs.

Herein, a surface site engineering strategy is used to construct a porous Z-scheme heterojunction photocatalyst for photocatalytic hydrogen evolution (PHE) by integration of BiOI in a mesoporous Zr-based metal–organic framework (MOF) NU-1000. Three high-quality and highly dispersed BiOI@NU-1000 heterojunction materials are synthesized, and a set of methods is used to characterize these materials, indicating that the BiOI@NU-1000 heterojunction can retain high porosity and crystallinity of the parent NU-1000. Furthermore, the built-in electric field of the BiOI@NU-1000 composite can effectively tune the band gap, promote the separation of photoinduced charge carriers, improve photocurrent intensity, and reduce photoelectric impedance. Under visible-light irradiation, BiOI@NU-1000-2 showed the best photocatalytic performance in the field of MOF-based photocatalysts for PHE, with a hydrogen production rate of up to 610 μmol h^–1 g^–1. This study will open up opportunities for the construction of Z-scheme photocatalysts based on the highly porous MOF materials to inspire the development of innovative photocatalysts.

Targeted synthesis, through a heteroleptic methodology, has resulted in three types of lanthanide (Ln) coordination polymers (CPs) with tailored dimensionality, tunable photoluminescent colors, and distinct luminescence quenching upon UV and X-ray irradiation. The homoleptic Ln(tpbz)(NO₃)₂ [CP-1; tpbz = 4-(2,2′:6′,2″-terpyridin-4′-yl)benzoate] is assembled from Ln cations and bridging tpbz ligands, accompanied by the decoration of NO₃^– anions, forming a one-dimensional (1D) chain structure. The presence of ancillary dicarboxylate linkers, 1,4-benzenedicarboxylate (bdc) and 2,5-thiophenedicarboxylate (tdc), promotes additional bridging between 1D chains to form a two-dimensional layer and a three-dimensional framework for Ln(tpbz)(bdc) (CP-2) and Ln(tpbz)(tdc) (CP-3), respectively. The multicolor and luminescence properties of the obtained CPs were investigated, displaying typical red Eu^III-based and green Tb^III-based emissions. The Sm^III-bearing CP-1–CP-3, however, exhibit diverse ratiometric Ln^III- and ligand-based emissions, with the photoluminescent colors varying from pink to orange to cyan. Notably, the Tb^III-containing CP-1–CP-3 display distinct luminescence quenching upon continuous exposure to UV and X-ray irradiation. To our best knowledge, CP-2-Tb represents one of the most sensitive UV dosage probes (3.2 × 10^–7 J) among all CPs.

Based on first-principles calculations with the DFT + U method, the couplings of lattice, charge, spin, and electronic behaviors underlying the Eu–Mn charge transfer in a strongly correlated system of EuMnO₃ were investigated. The potential valence transition from Eu³⁺/Mn³⁺ to Eu²⁺/Mn⁴⁺ was observed in a compressed lattice with little distortions, which is achieved under hydrostatic pressure and external strain. The intraplane antiferromagnetism (AFM) of Mn is proved to be instrumental in the emergence of Eu²⁺. Furthermore, we calculated the magnetic exchange interactions within two equilibrium structures of Eu³⁺Mn³⁺O₃ and Eu²⁺Mn⁴⁺O₃. Mn–Mn ferromagnetic exchange in the ab-plane is enhanced strongly in the Eu²⁺Mn⁴⁺O₃ structure, contributing to the existence of mixed states. The versatile electronic structures were obtained within the Eu²⁺Mn⁴⁺O₃ phase by imposing different magnetic configurations on the Eu and Mn sublattice, attributed to the coupling of charge transfer and magnetic orderings. It is found that the intraplane ferromagnetic ordering of Mn leads to a metallic electronic structure with the coexistence of Eu²⁺ and Eu³⁺, while the intraplane AFM Mn spin ordering leads to insulating states only with Eu²⁺. Notably, a half-metallic characteristic emerges at the magnetic ground state of CF ordering (C-type AFM for the Eu sublattice and ferromagnetic for the Mn sublattice), which makes such a supposed phase more intriguing than the conventional experimental phase. Additionally, the mixture of delocalized 4f with 5d states of Eu in the background of Mn 3d and O 2p orbitals implies a pathway of Eu 4f 5d ↔ O 2p ↔ Mn 3d for charge transfer between Eu and Mn. Our calculation shows that the Eu–Mn charge transfer could be expected in compressed EuMnO₃ and the introduction of Eu²⁺ 4f states near the Fermi level plays an important role in manipulating the interlinks of charge and spin together with electronic behaviors.

Metal–organic frameworks (MOFs) have attracted increasing research enthusiasm owing to their tunable functionality, diverse structure characteristics, and large surface area. However, poor hydrothermal stability restricts the utilization of some MOFs in practical applications. Our work aims at improving the hydrothermal stability of a representative MOF, namely, HKUST-1, by incorporating a two-dimensional material Ti₃C₂T_x MXene for the first time. A new type of hybrid material is synthesized through the hybridization of HKUST-1 and Ti₃C₂T_x, and the obtained hybrids show improved hydrothermal stability as well as catalytic performance. The porosity of hybrids is enhanced when incorporating an appropriate amount of Ti₃C₂T_x, and the surface area can reach 1380 m²·g^–1, while the pristine HKUST-1 is 1210 m²·g^–1. After the hydrothermal treatment (hot water vapor, 70 °C), the structure of hybrid materials maintains well, while the framework of HKUST-1 is severely destroyed. When catalyzing the ring-opening reaction of styrene oxide, the conversion reaches 76.7% only for 20 min, which is much higher than that of pure HKUST-1 (23.1% for 20 min). More importantly, the catalytic activity could recover without loss even after six cycles. Our hybrid materials are promising in practical catalytic applications due to their excellent hydrothermal stability, catalytic activity, and reusability.

Exploring new structural materials with strong He damage tolerance is one of the key tasks for the development of nuclear reactors. Helium (He), one of the most common elements in the nuclear environment, often forms undesired bubbles in metallic materials and may result in void swelling as well as high-temperature intergranular embrittlement. In this study, the behaviors of He in high-entropy alloy (HEA) TiZrHfMoNb and its constituents are systematically investigated both theoretically and experimentally. Density functional theory calculations show that the He atom prefers to occupy tetrahedral and octahedral interstitial sites in a HEA. The migration pathway for He in TiZrHfMoNb is explored and the migration energy barrier is determined. Besides, the He clustering behavior in TiZrHfMoNb is investigated. Through transmission electron microscopy analysis, a smaller He bubble size is observed in TiZrHfMoNb than in Ti, which is proposed to result from the lower tendency to form He clusters, a weaker coarsening effect, and severe lattice distortion in HEA. The current study thus provides deep insights into the He behaviors in HEAs and may help to develop structural materials with enhanced He damage tolerance in nuclear reactors.

The detailed structural characterization of “213” honeycomb systems is a key concern in a wide range of fundamental areas, such as frustrated magnetism, and technical applications, such as cathode materials, catalysts, and thermoelectric materials. Na₂LnO₃ (Ln = Ce, Pr, and Tb) are an intriguing series of “213” honeycomb systems because they host tetravalent lanthanides. “213” honeycomb materials have been reported to adopt either a cation-disordered R3̅m subcell, a cation-ordered trigonal (P3₁12), or monoclinic (C2/c or C2/m) supercell. On the basis of analysis of the average (synchrotron diffraction) and local [pair distribution function (PDF) and solid-state NMR] structure probes, cation ordering in the honeycomb layer of Na₂LnO₃ materials has been confirmed. Through rationalization of the ²³Na chemical shifts and quadrupolar coupling constants, the local environment of Na atoms was probed with no observed evidence of cation disorder. Through these studies, it is shown that the Na₂LnO₃ materials adopt a C2/c supercell derived from symmetry-breaking displacements of intralayered Na atoms from the ideal crystallographic position (in C2/m). The Na displacement is validated using distortion index parameters from diffraction data and atomic displacement parameters from PDF data. The C2/c supercell is faulted, as evidenced by the increased breadth of the superstructure diffraction peaks. DIFFaX simulations and structural considerations with a two-phase approach were employed to derive a suitable faulting model.

The new compound WTe₂I was prepared by a reaction of WTe₂ with iodine in a fused silica ampule at temperatures between 40 and 200 °C. Iodine atoms are intercalated into the van der Waals gap between tungsten ditelluride layers. As a result, the WTe₂ layer separation is significantly increased. Iodine atoms form planar layers between each tungsten ditelluride layer. Due to oxidation by iodine the semimetallic nature of WTe₂ is changed, as shown by comparative band structure calculations for WTe₂ and WTe₂I based on density functional theory. The calculated phonon band structure of WTe₂I indicates the presence of phonon instabilities related to charge density waves, leading to an observed incommensurate modulation of the iodine position within the layers.

A generalization of the modeling equation of optical band gap values for ternary oxides, as a function of cationic ratio composition, is carried out based on the semiempirical correlation between the differences in the electronegativity of oxygen and the average cationic electronegativity proposed some years ago. In this work, a novel approach is suggested to account for the differences in the band gap values of the different polymorphs of binary oxides as well as for ternary oxides existing in different crystalline structures. A preliminary test on the validity of the proposed modeling equations has been carried out by using the numerous experimental data pertaining to alumina and gallia polymorphs as well as the crystalline ternary Ga_(1–x)Al_xO₃ polymorphs (α-Ga_(1–x)Al_xO₃ and β-Ga_(1–x)Al_xO₃) covering a large range of optical band gap values (4.50–8.50 eV). To make a more rigorous test of the modeling equation, we extended our investigation to amorphous ternary oxides anodically formed on Al-d-metal alloys (Al-Nb, Al-Ta, and Al-W) covering a large range of d-metal composition (x_d-metal ≥ 0.2). In the last case, the novel approach allows one to overcome some difficulties experienced in fitting the optical band gap dependence from the Al-d-metal mixed anodic oxide composition as well as to provide a rationale for the departure, at the lowest d-metal content (x_d-metal < 0.2), from the behavior observed for anodic films containing higher d-metal content.

We show the synthesis and characterization of four heterobimetallic compounds derived from s-indacene of general formula [{(CO)₃Mn}-s-Ic-{MCp*}]^q with M = Fe, Co, Ni, and Ru; q = 0, 1+. The complexes reported here were characterized by ¹H and ¹³C NMR, elemental analysis and FT-IR. Additionally, the X-ray crystal structure of [(CO)₃Mn-s-Ic-FeCp*] (1) and Mössbauer spectra are reported. The heterobimetallic compounds exhibit higher quasireversible redox potentials compared with ferrocene and catocene under the same reaction conditions. The complexes were tested as catalysts on the thermal decomposition of ammonium perchlorate examined by a differential scanning calorimetry technique to study their catalytic behavior. Compound (1) causes a decrease of ammonium perchlorate’s decomposition temperature to 315 °C, consequently increasing the heat release by 138 J·g^–1. Conversely, [{(CO)₃Mn}-s-Ic′-{CoCp*}] (2) presents a higher heat release (2462 J·g^–1), comparable to catocene.

The development of cost-effective, functional materials that can be efficiently used for sustainable energy generation is highly desirable. Herein, a new molecular precursor of bismuth (tris(selenobenzoato)bismuth(III), [Bi(SeOCPh)₃]), has been used to prepare selectively Bi or Bi₂Se₃ nanosheets via a colloidal route by the judicious control of the reaction parameters. The Bi formation mechanism was investigated, and it was observed that the trioctylphosphine (TOP) plays a crucial role in the formation of Bi. Employing the vapor deposition method resulted in the formation of exclusively Bi₂Se₃ films at different temperatures. The synthesized nanomaterials and films were characterized by p-XRD, TEM, Raman, SEM, EDX, AFM, XPS, and UV–vis spectroscopy. A minimum sheet thickness of 3.6 nm (i.e., a thickness of 8–9 layers) was observed for bismuth, whereas a thickness of 4 nm (i.e., a thickness of 4 layers) was observed for Bi₂Se₃ nanosheets. XPS showed surface oxidation of both materials and indicated an uncapped surface of Bi, whereas Bi₂Se₃ had a capping layer of oleylamine, resulting in reduced surface oxidation. The potential of Bi and Bi₂Se₃ nanosheets was tested for overall water-splitting application. The OER and HER catalytic performances of Bi₂Se₃ indicate overpotentials of 385 mV at 10 mA cm^–2 and 220 mV, with Tafel slopes of 122 and 178 mV dec^–1, respectively. In comparison, Bi showed a much lower OER activity (506 mV at 10 mA cm^–2) but a slightly better HER (214 mV at 10 mA cm^–2) performance. Similarly, Bi₂Se₃ nanosheets were observed to exhibit cathodic photocurrent in photoelectrocatalytic activity, which indicated their p-type behavior.

To date, the experimental studies on Nd-based metallofullerenes are only limited to spectroscopic characterizations. In this work, the molecular structures of Nd@C₈₂(I,II) isomers, including the isomeric symmetry of the C cage and the position of endohedral Nd atom, as well as their unique two-dimensional (2D)-layered crystallographic packing structures were initially and unambiguously elucidated, based on the X-ray structural analyses of the cocrystals of Nd@C₈₂(I) or Nd@C₈₂(II) with cocrystallizing agent decapyrrylcorannulene (DPC). In the V-shaped unit cell, the endohedral Nd atom prefers a site as far away from the DPC molecules as possible because of the unevenly distributed charge on the C cage mainly related to the charge transfers from the endohedral Nd atom, cocrystallizing agent DPC, and solvent toluene molecules to the C₈₂ cage. Apart from charge transfers, multiple C–H···π intermolecular interactions are also confirmed to play important roles both for the orientation of the C cage correlated with the preferential sites of the endohedral Nd atom and for the 2D-layered packing structures within the cocrystals. Density functional theory computations offered theoretical support for the molecular structures of Nd@C₈₂(I,II) isomers, the valence of the endohedral Nd atom (between II+ and III+), and the global ground state, i.e., the Nd@C_2v(9)-C₈₂ isomer in the quintet state.

The linkage of molecular components into functional heterogeneous framework materials has revolutionized modern materials chemistry. Here, we use this principle to design polyoxometalate-based frameworks as high affinity adsorbents for drugs of abuse, leading to their application in solid-phase extraction analysis. The frameworks are assembled by the reaction of a Keggin-type polyanion, [SiW₁₂O₄₀]^4–, with lanthanoids Dy(III), La(III), Nd(III), and Sm(III) and the multidentate linking ligand 1,10-phenanthroline-2,9-dicarboxylic acid (H₂PDA). Their reaction leads to the formation of crystalline 1D coordination polymers. Because of the charge mismatch between the lanthanoids (+3) and the dodecasilicotungstate (−4), we observe incorporation of the PDA^2– ligands into crystalline materials, leading to four polyoxometalate-based frameworks where Keggin-type heteropolyanions are linked by cationic {Ln_n(PDA)_n} groups (Ln = Dy (1), La (2), Nd (3), and Sm (4)). Structural analysis of the polyoxometalate-based frameworks suggested that they might be suitable for surface binding of common drugs of abuse via supramolecular interactions. To this end, they were used for the extraction and quantitative determination of four model drugs of abuse (amphetamine, methamphetamine, codeine, and morphine) by using micro-solid-phase extraction (D-μSPE) and high-performance liquid chromatography (HPLC). The method showed wide linear ranges, low limits of detection (0.1–0.3 ng mL^–1), high precision, and satisfactory spiked recoveries. Our results demonstrate that polyoxometalate-based frameworks are suitable sorbents in D-μSPE for molecules containing amine functionalities. The modular design of these networks could in the future be used to expand and tune their substrate binding behavior.

Graphene materials with particular properties are proved to be beneficial to photoelectric devices, but there are rare reports on a positive effect by graphene on emissive layer materials of organic light-emitting diodes (OLEDs) previously. On the basis of the latest important experiments, an OLED device with the aid of graphene quantum dots shows the dawn of their application for luminescent materials. The luminescence performance has been improved, but the understanding of the internal excited-state radiation mechanism of the material needs further study. In this work, the Pt(II)-coordinated graphene quantum dot coplanar structures with different shapes are studied theoretically in detail, and the results present the improvement in phosphorescence under the promoted radiative decay and suppressed nonradiative decay. This composite combines the advantages of transition metal complexes and graphene quantum dots and also exhibits excellent properties in the light absorption region and carrier transportation for the OLED. This comprehensive theoretical calculation research can provide a comprehensive basis of the material design in the future.

In recent years, low-dimensional lead halides have emerged as some of most attractive photoelectric materials due to their intrinsic broadband emissions with a potential application in white-light emitting diodes. To achieve the desired performance, tremendous research has emphasized the modulation of inorganic components as optical centers; however, less work has paid attention to the direct contribution of the organic components. Herein, we successfully assembled two new hybrid lead halides of [H₂BPP]Pb₂X₆ (X = Br, 1, and Cl, 2) containing one-dimensional double [Pb₂X₆]^2– chains using optically active 1,3-bis(4-pyridyl)-propane (BPP) as an organic cation. Under UV-light excitation, compounds 1 and 2 exhibit broadband yellowish-green emissions, which were verified by promising photoluminescence quantum efficiencies (PLQEs) of 8.10% and 4.84%, respectively. The broadband light emissions are derived from the combination of dual higher-energy blue and lower-energy yellow light spectra, which can be attributed to the individual contributions of the organic and inorganic components, respectively, according to the time-resolved and temperature-dependent emission spectra as well as theoretical calculations. This work proves the great contribution of organic components to the photophysical properties and provides a new design strategy to realize broadband light emission by rationally combining the dual-emitting properties of different assembly blocks.

Zn₂GeO₄ is a multifunctional material whose intrinsic thermal expansion properties below ambient temperature have not been explored until now. Herein, the thermal expansion of Zn₂GeO₄ is investigated by synchrotron X-ray diffraction, with the finding that Zn₂GeO₄ exhibits very low negative (α_v = −2.02 × 10^–6 K^–1, 100–300 K) and positive (α_v = +2.54 × 10^–6 K^–1, 300–475 K) thermal expansion below and above room temperature, respectively. A combined study of neutron powder diffraction and extended X-ray absorption fine structure spectroscopy shows that the negative thermal expansion (NTE) of Zn₂GeO₄ originates from the transverse vibrations of O atoms in the four- and six-membered rings with ZnO₄–GeO₄ tetrahedra. In addition, the results of temperature- and pressure-dependent Raman spectra identify the low-frequency phonon modes (50–150 cm^–1) with negative Grüneisen parameters softening upon pressuring and stiffening upon heating during the lattice contraction, thus contributing to the NTE. This study not only reports the interesting thermal expansion behavior of Zn₂GeO₄ but also provides further insights into the NTE mechanism of novel structures.

Krypton (Kr) and xenon (Xe) are nowadays widely applied in technical and industrial fields. Separating and collecting highly pure Xe from nuclear facilities are necessary and urgent. However, the technology is limited due to the inert nature of Xe and other interferential factors. In this work, a calcium-based metal–organic framework, Ca-SINAP-1, which comprises a three-dimensional microporous framework with a suitable pore width, was researched for xenon and krypton separation through both experimental and theoretical methods. Ca-SINAP-1, synthesized in solvothermal and gamma ray conditions, features accessible open-metal sites, exhibits a high Xe/Kr selectivity of 10.32, and owns a Xe adsorption capacity of 2.87 mmol/g at room temperature (1.0 bar). Particularly, its excellent chemical stability (from pH 2 to 13) and thermal stability (up to 550 °C), as well as radiation-resistance (up to 400 kGy β irradiations), render this material a promising candidate for radioactive inert gases treatment.

The synthesis and photophysical properties of the heteropolynuclear Pt–Ag complex having cyclometalated rollover bipyridine ligands (bpy*) and bridging pyrazolato ligands are reported. The Pt₂Ag₂ complex was synthesized by two step reactions from a Pt(II) complex precursor having the rollover bpy* ligand, [Pt(bpy*)(dmso)Cl], with 3,5-dimethylpyrazole (Me₂pzH) and a subsequent replacement of NH protons in the Me₂pzH moieties with the Ag(I) ion. The Pt₂Ag₂ complex exists as a mixture of U- and Z-shaped isomers in solution, whose structures were clearly determined by single-crystal X-ray structural analyses. NMR studies using the single crystals revealed rapid isomerization of the Pt₂Ag₂ complexes in solution, although the Pt₂Ag₂ structures were supported effectively by the multiple metal–metal interactions. Furthermore, the Pt₂Ag₂ framework can capture a Ag(I) ion during the U–Z isomerization to afford a Pt₂Ag₃ core with the formation of Pt → Ag dative bonds. The Pt₂Ag₃ complex showed further aggregation to form a dimer structure in the presence of coordinating solvent via the crystallization process. The formation of Pt → Ag dative bonds significantly changes the emission energy from the Pt₂Ag₂ complex, while the emission spectra of U- and Z-isomers of Pt₂Ag₂ complex almost coincide with each other and their emissive properties are very similar. The density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations revealed the effects of additional Ag(I) ion on the photophysical properties of the heteropolynuclear Pt–Ag complexes bearing the rollover bpy* ligands.

A high-nucleus silver nanopolycluster as a new type of silver-based polymer supercapacitor (SSc) by a simple and single-step synthesis process was designed and synthesized. The structural, optical, and electrochemical properties of SSc-2 were determined. This highly stable conductive 3D nanopolycluster shows great cycling stability, large capacity, and high energy density without any modification or doping process and so acts as an excellent SSc (412 F g^–1 at 1.5 A g^–1). In addition, there was a stable cycling performance (94% capacitance) following 7000 cycles at 3 A g^–1 current density. The presence of fluorinated groups, 3D expansion of high-nucleus metallic clusters, and porosity are the advantages of SSc-2 that lead to stability, conductivity, and high capacity, respectively. These results lead to the development of a novel kind of SSc by overcoming the low conductivity and limited capacity challenges without any modification.

Sm₂Fe₁₇ compounds are high-performance permanent magnets. Cobalt substitution allows us to further improve their magnetic properties. Depending on the thermal treatment, cobalt-substituted compounds can be synthesized either in the TbCu₇ (disordered) or in the Th₂Zn₁₇ (ordered) structure type. Rietveld refinement of the number of transition metal dumbbells replacing rare-earth atoms from synchrotron powder diffraction data shows that the TbCu₇ disordered structure has the same composition as the ordered one (a transition metal-to-rare earth ratio of 8.5). Then, cobalt site occupancies have been determined in both structures using synchrotron resonant (anomalous) diffraction. Cobalt is found to be absent from the dumbbell sites. The diffraction results are confirmed by Mössbauer spectroscopy.

We examined the ZnGeN₂–GaN solid-solution system (Zn_1–xGe_1–xGa_2xN₂) in the unexplored compositional region of x < 0.10 to reveal the transitional structural and optical properties caused by the introduction of Ga. Fairly stoichiometric fine powder specimens with compositions of x = 0.02 and 0.05 were prepared by the gas-reduction–nitridation method, and their partially ordered Pna2₁ structure was identified by solid-state ⁷¹Ga NMR spectroscopy and time-of-flight neutron powder diffraction. The Rietveld refinement results of the neutron diffraction data showed that the introduction of 2 atom % Ga readily retards the cation ordering in ZnGeN₂, and this composition-induced transition to the wurtzite disordered phase proceeds mostly in the range of x < 0.10. The synthesized samples showed gradual red shifts of the absorbance and photoluminescence excitation spectra with their x value, consistent with their degree of disorder, indicating that the narrowing of the band gap achieved in the current system results primarily from the disorder of the cation sublattice accompanied by octet-rule violation, as has been predicted theoretically. The test reactions for photocatalytic water splitting resulted in improved H₂ evolution rates of 6.1–72.6 μmol/h under UV–visible-light irradiation, and stable solar H₂ evolution of up to 5 days was demonstrated.

Two different four-electron reductions of dioxygen (O₂) on a metal surface are reproduced in homogeneous systems. The reaction of the highly unsaturated (56-electron) tetraruthenium tetrahydride complex 1 with O₂ readily afforded the bis(μ₃-oxo) complex 3 via a dissociative mechanism that includes large electronic and geometric changes, i.e., a four-electron oxidation of the metal centers and an increase of 8 in the number of valence electrons. In contrast, the tetraruthenium hexahydride complex 2 induces a smooth H-atom transfer to the incorporated O₂ species, and the O–OH bond is cleaved to afford the mono(μ₃-oxo) complex 4 via an associative mechanism. Density functional theory calculations suggest that the higher degree of unsaturation in the tetrahydride system induces a significant interaction between the tetraruthenium core and the O₂ moiety, enabling the large changes required for the dissociative mechanism.

We report a computational survey of chemical doping of silver(II) fluoride, which has recently attracted attention as an analogue of La₂CuO₄—a known precursor of high-temperature superconductors. By introducing fluorine defects (vacancies or interstitial adatoms) into the crystal structure, we obtain nonstoichiometric, electron- and hole-doped polymorphs of AgF_2±x. We find that the ground-state solutions show a strong tendency for localization of defects and of the associated electronic states, and the resulting doped phases exhibit insulating or semiconducting properties. Furthermore, the distribution of Ag(I)/Ag(III) sites which appear in the crystal structure points to the propensity of the AgF₂ system for phase separation upon chemical doping, which is in line with observations from previous experimental attempts. Overall, our results indicate that chemical modification may not be a feasible way to achieve doping in bulk silver(II) fluoride, which is considered essential for the emergence of high-T_c superconductivity.

Ionic metal–organic frameworks (MOFs) with an ionic skeleton and unique porous structures could selectively adsorb charged dyes with specific dimensions. However, the ion-exchange-based and size-exclusion-based process as a chromatography method needs to be further explored. In this study, a new microporous anionic MOF, JUC-210, was synthesized using a spirobifluorene-based ligand and trivalent metal indium. JUC-210 has a two-fold interpenetrated pts framework with a large void space, possessing suitable pore sizes and an anionic skeleton for efficient separation of certain organic dyes. Different types of dyes were used to observe the selective adsorption ability of the as-synthesized MOF. JUC-210 displayed high selective adsorption toward the cationic dye methylene blue with positive charges based on ion exchange and size exclusion. Moreover, the effect of solvent on the selective adsorption behaviors of JUC-210 was investigated. The exploration of novel MOF materials would provide potential efficient adsorbents for separation of organic dyes.

The ligand-centered hydrogen-atom-transfer (HAT) reactivity was examined for a family of group 10 metal complexes containing a tridentate pincer ligand derived from bis(2-mercapto-p-tolyl)amine, [SNS]H₃. Six new metal complexes of palladium and platinum were synthesized with the [SNS] ligand platform in different redox and protonation states to complete the group 10 series previously reported with nickel. The HAT reactivity was examined for this family of nickel, palladium, and platinum complexes to determine the impact of a metal ion on the ligand-centered reactivity. Thermodynamic measurements revealed that N–H bond dissociation free energies increased by approximately 10 kcal mol^–1 along the series Ni < Pd < Pt driven by changes to both the redox potential and pK_a of the ligand. Kinetic analyses for all three metal complexes suggest that the barrier to the HAT reactivity is primarily entropic rather than enthalpic for this system.

Coordination numbers and geometries form a theoretical framework for understanding and predicting materials properties. Algorithms to determine coordination numbers automatically are increasingly used for machine learning (ML) and automatic structural analysis. In this work, we introduce MaterialsCoord, a benchmark suite containing 56 experimentally derived crystal structures (spanning elements, binaries, and ternary compounds) and their corresponding coordination environments as described in the research literature. We also describe CrystalNN, a novel algorithm for determining near neighbors. We compare CrystalNN against seven existing near-neighbor algorithms on the MaterialsCoord benchmark, finding CrystalNN to perform similarly to several well-established algorithms. For each algorithm, we also assess computational demand and sensitivity toward small perturbations that mimic thermal motion. Finally, we investigate the similarity between bonding algorithms when applied to the Materials Project database. We expect that this work will aid the development of coordination prediction algorithms as well as improve structural descriptors for ML and other applications.

Developing highly efficient non-precious electrocatalytic materials for H₂ production in an alkaline medium is attractive on the front of green energy production. Herein, we successfully designed an electrocatalyst with superb hydrophilicity, high conductivity, and a kinetically beneficial structure using Ni₂P/MXene over a 3D Ni foam (NF) for the alkaline hydrogen evolution reaction (HER) based on the laboratory and computational research works. The designed self-supported and highly effective electrocatalyst achieves a huge boost in the HER activity compared with that of pristine Ni₂P nanosheets owing to the distinctive structure and synergy of coupling Ti₃C₂T_x and Ni₂P. More specifically, Ni₂P/Ti₃C₂T_x/NF produces an electric current density of 10 mA·cm^–2 under a low overpotential (135 mV) and shows excellent durability under alkaline (1 M KOH) conditions, and the observed performance degradation is negligible. The outstanding HER activity makes the synthetic strategy of Ni₂P/Ti₃C₂T_x/NF a potential approach to be extended to other transition-metal-based electrocatalysts for enhanced catalytic performance.

The controlled incorporation of dopants like copper into ZnO nanowires (NWs) grown by chemical bath deposition (CBD) is still challenging despite its critical importance for the development of piezoelectric devices. In this context, the effects of the addition of copper nitrate during the CBD of ZnO NWs grown on Au seed layers are investigated in detail, where zinc nitrate and hexamethylenetetramine are used as standard chemical precursors and ammonia as an additive to tune the pH. By combining thermodynamic simulations with chemical and structural analyses, we show that copper oxide nanocrystals simultaneously form with ZnO NWs during the CBD process in the low-pH region associated with large supersaturation of Cu species. The Cu(II) and Zn(II) speciation diagrams reveal that both species show very similar behaviors, as they predominantly form either X²⁺ ions (with X = Cu or Zn) or X(NH₃)₄²⁺ ion complexes, depending on the pH value. Owing to their similar ionic structures, Cu²⁺ and Cu(NH₃)₄²⁺ ions preferentially formed in the low- and high-pH regions, respectively, are able to compete with the corresponding Zn²⁺ and Zn(NH₃)₄²⁺ ions to adsorb on the c-plane top facets of ZnO NWs despite repulsive electrostatic interactions, yielding the significant incorporation of Cu. At the highest pH value, additional attractive electrostatic interactions between the Cu(NH₃)₄²⁺ ion complexes and negatively charged c-plane top facets further enhance the incorporation of Cu into ZnO NWs. The present findings provide a deep insight into the physicochemical processes at work during the CBD of ZnO NWs following the addition of copper nitrate, as well as a detailed analysis of the incorporation mechanisms of Cu into ZnO NWs, which are considered beyond the only electrostatic forces usually driving the incorporation of dopants such as Al and Ga.

Bimetallic transition-metal phosphides are gradually evolving as efficient hydrogen evolution catalysts. In this study, graphene-coated MoP and bimetallic phosphide (MoNiP) nanoparticles (MoP/MoNiP@C) were synthesized via one-step straightforward high-temperature calcination and phosphating process. The precursor was obtained from polyaniline, Ni²⁺ ions, and phosphomolybdic acid hydrate (PMo₁₂) by solvent evaporation. As expected, MoP/MoNiP@C manifests excellent hydrogen evolution activity with a low overpotential of 134 mV at 10 mA cm^–2 and a small Tafel slope of 66 mV dec^–1. Furthermore, MoP/MoNiP@C exhibits satisfactory stability for 24 h in the acid electrolyte. The outstanding catalytic performance can be attributed to the synergistic effect of MoP and MoNiP nanoparticles, the graphene coating protecting MoP and MoNiP from corrosion, as well as an increase in the number of active sites because of porous structures. This work can provide the experimental foundation for the simple synthesis of bimetallic phosphates with remarkable hydrogen evolution performance.

This work complements our recent discovery of new phases derived from zirconium perchlorate by addition of hydrogen peroxide. Here, we investigate analogous reactions with hafnium perchlorate, which is found to have modifications of the Clearfield–Vaughan tetramer (CVT). For hafnium perchlorate derivatives, we find distorted versions of CVT by X-ray diffraction and study the reaction solutions by SAXS, Raman spectroscopy, and ESI-MS. Furthermore, we investigate mixed Hf–Zr solution and solid phases and find the latter resemble the zirconium family at low Hf concentrations and the hafnium family at higher hafnium contents.

The syntheses, crystal structures, and catalytic radical scavenging activity are reported for four new molecular clusters that have resulted from a bottom-up molecular approach to nanoscale CeO₂. They are [Ce₆O₄(OH)₄(dmb)₁₂(H₂O)₄] (dmb^– = 2,6-dimethoxybenzoate), [Ce₁₆O₁₇(OH)₆(O₂CPh)₂₄(HO₂CPh)₄], [Ce₁₉O₁₈(OH)₉(O₂CPh)₂₇(H₂O)(py)₃], and [Ce₂₄O₂₇(OH)₉(O₂CPh)₃₀(py)₄]. They represent a major expansion of our family of so-called “molecular nanoparticles” of this metal oxide to seven members, and their crystal structures confirm that their cores all possess the fluorite structure of bulk CeO₂. In addition, they have allowed the identification of surface features such as the close location of multiple Ce³⁺ ions and organic ligand binding modes not seen previously. The ability of all seven members to catalytically scavenge reactive oxygen species has been investigated using HO^• radicals, an important test reaction in the ceria nanoparticle biomedical literature, and most have been found to exhibit excellent antioxidant activities compared to traditional ceria nanoparticles, with their activity correlating inversely with their surface Ce³⁺ content.

The recently reported hypersilylsilylene PhC(NtBu)₂SiSi(SiMe₃)₃ (1) reacts with BH₃, 9-BBN, and PhBCl₂ to yield the respective Lewis acid base adducts 2–4, respectively. Compound 4 undergoes isomerization to form a ring expansion product 5. The same silylene was found to initially form an adduct with HBpin (6) and subsequently isomerized to 7 via the rupture of the B–H bond of HBpin (7), where the hydride was bound to the carbon atom of the amidinate ligand and the Bpin unit was attached to the silicon center. Surprisingly, the reaction of 1 with HBcat results in PhC(NtBu)₂Bcat (8). Subsequently, we have shown that HBcat forms the same product when it reacts with related silylene PhC(NtBu)₂SiN(SiMe₃)₃ (1′). With all of these reactions in hand, we ponder if silylene can activate two small molecules at one time. In this work, we delineate the three-component reactions of silylenes 1 and 1′ with 4-fluorobenzaldehyde and HBpin, which afforded unusual coupling products, 9 and 10, respectively. Note that 9 and 10 were prepared from the cleavage of the B–H and C═O bonds by silylene in a single reaction and are the first structurally attested Si–C–O–B coupled products.

Owing to their characteristic structures, metal–organic frameworks (MOFs) are considered as the leading candidate for drug-delivery materials. However, controlling the synthesis of MOFs with uniform morphology and high drug-loading/release efficiencies is still challenging, which greatly limits their applications and promotion. Herein, a multifunctional MOF-based drug-delivery system (DDS) with a controlled pore size of 100–200 nm for both therapeutic and bioimaging purposes was successfully synthesized in one step. Fe-MOF-based microcapsules were synthesized through a competitive coordination method, which was profited from the intrinsic coordination characteristics of the Fe element and the host-guest supramolecular interactions between Fe³⁺ and polyoxometalates anions. This as-synthesized macroporous DDS could greatly increase the drug-loading/release rate (77%; 83%) and serve as a magnetic resonance (MR) contrast agent. Because an Fe-containing macroporous DDS presents ultrahigh drug loading/release, the obtained 5-FU/Fe-MOF-based microcapsules displayed good biocompatibility, extremely powerful inhibition of tumor growth, and satisfactory MR imaging capability. Given all these advantages, this study integrates high therapeutic effect and diagnostic capability via a simple and effective morphology-controlling strategy, aiming at further facilitating the applications of MOFs in multifunctional drug delivery.

The novel photosensitizer [Ru(^S–Sbpy)(bpy)₂]²⁺ harbors two distinct sets of excited states in the UV/Vis region of the absorption spectrum located on either bpy or ^S–Sbpy ligands. Here, we address the question of whether following excitation into these two types of states could lead to the formation of different long-lived excited states from where energy transfer to a reactive species could occur. Femtosecond transient absorption spectroscopy identifies the formation of the final state within 80 fs for both excitation wavelengths. The recorded spectra hint at very similar dynamics following excitation toward either the parent or sulfur-decorated bpy ligands, indicating ultrafast interconversion into a unique excited-state species regardless of the initial state. Non-adiabatic surface hopping dynamics simulations show that ultrafast spin–orbit-mediated mixing of the states within less than 50 fs strongly increases the localization of the excited electron at the ^S–Sbpy ligand. Extensive structural relaxation within this sulfurated ligand is possible, via S–S bond cleavage that results in triplet state energies that are lower than those in the analogue [Ru(bpy)₃]²⁺. This structural relaxation upon localization of the charge on ^S–Sbpy is found to be the reason for the formation of a single long-lived species independent of the excitation wavelength.

Kemp’s triacid (cis,cis-1,3,5-trimethylcyclohexane-1,3,5-tricarboxylic acid, H₃kta) was reacted with uranyl nitrate under solvo-hydrothermal conditions in the presence of diverse counterions or additional metal cations to give eight zero- or diperiodic complexes. All the coordination polymers in the series, [PPh₃Me][UO₂(kta)]·0.5H₂O (1), [PPh₄][UO₂(kta)] (2), [C(NH₂)₃][UO₂(kta)] (3), [Cd(bipy)₃][UO₂(kta)]₂ (4), and [Zn(phen)₃][UO₂(kta)]₂·2H₂O (5) (bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline) crystallize as networks with the hcb topology, the ligand being in the chair conformation with the three carboxylate groups equatorial, except in 3, in which the axial/diequatorial boat conformation is present. Various degrees of corrugation and different arrangements of neighboring layers are observed depending on the counterion, with complexes 4 and 5, in particular, displaying cavities containing the bulky cations. [Co(en)₃]₂[(UO₂)₂(kta)(Hkta)₂]₂·2NMP·10H₂O (6) (en = 1,2-ethanediamine; NMP = N-methyl-2-pyrrolidone) contains a metallatricyclic, tetranuclear anionic species, displaying two clefts in which the cations are held by extensive hydrogen bonding, and with the ligands in both triaxial chair and axial/diequatorial boat conformations. [(UO₂)₃Pb(kta)₂(Hkta)(H₂O)]₂·1.5THF (7) (THF = tetrahydrofuran) and [(UO₂)₂Pb₂(kta)₂(Hkta)(NMP)]₂ (8) are two heterometallic cage compounds containing only the convergent, triaxial chair form of the ligand, which have the same topology in spite of the different U/Pb ratio. These complexes are compared to previous ones also involving Kemp’s triacid anions, and the roles of ligand conformation and of counterions in the formation of cavities, either in cage-like species or as grooves in diperiodic networks, is discussed.

Crystal facet engineering, a trending technique to acquire superior exciton pair anti-recombination and interfacial charge pair separation via an inherent functional exposed facet isotype junction, is the current research hotspot. Selectively controlling facet exposure factor with Schottky energy barrier architecture across discerned exposed functional facet attested to facilitate electron injection-separation via a shorter barrier height and closer surface distance. In this context, a {040/110}-BiVO₄@Ag@CoAl-LDH Z-scheme isotype heterostructure with elevated {040} facet exposure factor tailored a {040/110} crystal facet isotype junction, and {040}-BiVO₄ functional facet/metallic Ag⁰ nano-island semiconductor–metal selective Schottky contact was fabricated meticulously via a three-step reflux, photoreduction, followed by an in situ co-precipitation method. Inherent attribution of crystal facet isotype junction and minor semiconductor–metal Schottky barrier toward the nature of exciton pair separation and elevated photoredox activity was neatly demonstrated and well inferred, which is the novelty of the present research. The ternary isotype heterostructure corroborates impressive gemifloxacin detoxification (89.72%, 90 min) and O₂ generation (768 μmol, 120 min), which are multiple folds that of respective pure and binary isotype heterostructures. The bottom-up photoredox activity was well ascribed to shorter Schottky barrier hot electron channelization provoked superior exciton pair separation and well attested via linear sweep voltammetry (315 μA), photoluminescence, electrochemical impedance spectroscopy, Bode, carrier density, and transient photocurrent analysis. The research illustrates a novel insight and scientific basis for the rational design of crystal facet isotype junction and selective Schottky contact vectorial electron shuttling promoted Z-scheme charge transfer dynamics isotype heterostructure systems toward photocatalytic energy-environmental remediation.

Metal–organic frameworks (MOFs) and MOF-based composites as luminescent sensors with excellent economic practicability and handy operability have attracted much attention. Herein, we designed and fabricated a porous Zn-based MOF, [Zn(OBA)₂(L₁)·2DMA]_n [1; H₂OBA = 4,4′-oxybis(benzoic acid), L₁ = 2,4,6-tris(4-pyridyl)pyridine, and DMA = N,N-dimethylacetamide], with mixed nodes under solvothermal conditions, and the pore size of 5.9 Å was calculated from N₂ adsorption isotherms by using a density functional theory model. The as-synthesized compound 1 is stable in different boiling organic solvents and water solutions with a wide pH range of 2–12 and exhibits intense luminescence emission at 360 nm under excitation of 290 nm. Significantly, compound 1 shows high selective detection of Fe³⁺, CrO₄^2–, and Cr₂O₇^2– in aqueous solution even under the interference of other ions. Compound 1 can quickly sense these ions in a short time and has a striking sensitivity toward Fe³⁺ with an ultralow limit of detection (LOD) of 1.06 μM. The relatively low LODs for CrO₄^2– and Cr₂O₇^2– are 3.87 and 2.37 μM, respectively, compared to the reported works. Meanwhile, compound 1 can be reused to detect Fe³⁺, CrO₄^2–, and Cr₂O₇^2– six times by simple regeneration. Considering the practicability, a mixed-matrix membrane (MMM) incorporated compound 1 and poly(methyl methacrylate) has been constructed. This MMM displays quick detection of Fe³⁺, CrO₄^2–, and Cr₂O₇^2– and prompt regeneration by lifting from the analyte. This useful MMM shows a comparable LOD below 4.35 μM for these ions. This work presents a cost-effective Zn-based MOF as a functional platform for simple but useful sensing of Fe³⁺, CrO₄^2–, and Cr₂O₇^2– in aqueous solution.

Linker elongation is an important method to systematically adjust porosity and pore size in isoreticular MOFs. In flexible structures, this approach opens the possibility for the systematic analysis of the building blocks and their contribution to the overall flexible behavior enabling tuning of the framework responsivity toward molecular stimuli. In this work, we report two new compounds isoreticular to the highly flexible pillared layer structure DUT-8(Ni) ([Ni₂(2,6-ndc)₂(dabco)]_n, 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicylo[2.2.2]octane). Aromatic linker 2,6-ndc was substituted by longer carboxylic linkers, namely, 4,4′-biphenyldicarboxylate (4,4′-bpdc) and 4,4′-stilbenedicarboxylate (4,4′-sdc), while the dabco pillar was retained. The structural response of the new compounds toward the desolvation and adsorption of various fluids was studied using advanced in situ PXRD techniques, demonstrating distinct differences in the flexible behavior of three compounds and disclosing the impact of linker structure on the framework response. Theoretical calculations provide mechanistic insights and an energetic rationale for the pronounced differences in switchability observed. The energetics of linker bending and linker–linker dispersion interactions govern the phase transitions in investigated MOFs.

A tetra-armed cyclen (L) with two substituted 3,5-difluorobenzyl and two substituted pyridine-4-yl methyl groups at the 1,4- and 7,10-positions of the cyclen ring as side arms was synthesized. When L was reacted with 1 equiv of the silver(I), dimetallo[3.3]paracyclophane-like 2:2 cyclic dimer, [Ag₂(L)₂](PF₆)₂, was obtained. The reaction of L with 2 equiv of silver(I) gave a 3:6 cyclic trimer, [Ag₆(L)₃(CH₃CN)₃](OTf)₆·3CH₃CN. Furthermore, reversible complexation between the 2:2 cyclic dimer and 3:6 cyclic trimer was confirmed by ¹H NMR and the CSI mass in the addition of silver(I) or the [2.2.2]cryptand.

The quest for new transition metal dichalcogenides (TMDs) with outstanding electronic properties operating under ambient conditions draws us to investigate the 1T-HfSe₂ polytype under hydrostatic pressure. Diamond anvil cell (DAC) devices coupled to in situ synchrotron X-ray, Raman, and optical (VIS–NIR) absorption experiments along with density functional theory (DFT)-based calculations prove that (i) bulk 1T-HfSe₂ exhibits strong structural and vibrational anisotropies, being the interlayer direction especially sensitive to pressure changes, (ii) the indirect gap of 1T-HfSe₂ tends to vanish by a −0.1 eV/GPa pressure rate, slightly faster than MoS₂ or WS₂, (iii) the onset of the metallic behavior appears at P_met ∼10 GPa, which is to date the lowest pressure among common TMDs, and finally, (iv) the electronic transition is explained by the bulk modulus B₀-P_met correlation, along with the pressure coefficient of the band gap, in terms of the electronic overlap between chalcogenide p-type and metal d-type orbitals. Overall, our findings identify 1T-HfSe₂ as a new efficient TMD material with potential multipurpose technological applications.

Z-scheme g-C₃N₄/Ag₃VO₄/reduced graphene oxide (rGO) photocatalysts with multi-interfacial electron-transfer paths enhancing CO₂ photoreduction under UV–vis light irradiation were successfully prepared by a hydrothermal process. Transmission electron microscope images displayed that the prepared photocatalysts have a unique 2D–0D–2D ternary sandwich structure. Photoelectrochemical characterizations including TPR, electrochemical impedance spectroscopy, photoluminescence, and linear sweep voltammetry explained that the multi-interfacial structure effectively improved the separation and transmission capabilities of photogenerated carriers. Electron spin resonance spectroscopy and band position analysis proved that the electron-transfer mode of g-C₃N₄/Ag₃VO₄ meets the Z-scheme mechanism. The introduction of rGO provided more electron-transfer paths for the photocatalysts and enhanced the stability of Ag-based semiconductors. In addition, the π–π conjugation effect between g-C₃N₄ and rGO further improved the generation and separation efficiency of photogenerated electron–hole pairs. Then, the multiple channels (Ag₃VO₄ → CN, Ag₃VO₄ → rGO → CN, and rGO → CN) due to the 2D–0D–2D structure greatly improving the photocatalytic CO₂ reduction ability have been discussed in detail.

Chromium germanides, namely, Nowotny chimney-ladder-phase CrGe_1.77 and MoSi₂-type CrGe₂, were synthesized above 15 GPa or more via laser heating using a diamond anvil cell (LHDAC). MoSi₂-type CrGe₂, which is the most Ge-rich compound in the Cr–Ge system, crystallizes in the tetragonal structure with a space group of I4/mmm (no. 139) and lattice parameters of a = 3.24919(6) Å and c = 8.0523(3) Å and is isostructural with MoSi₂. MoSi₂-type CrGe₂ has a deep pseudogap caused by the splitting of 3d orbitals with Cr, as evidenced by ab initio calculation. In this article, we have succeeded in synthesizing a binary compound between transition-metal and metalloid elements for the first time at high pressures above 10 GPa using the LHDAC. This pathway opens the possibility to explore more compounds in this system and may provide new insights into the fundamental interaction between these two elements.

A novel ternary nitride semiconductor, CaSnN₂, with a layered rock-salt-type structure (R3̅m) was synthesized via a high-pressure metathesis reaction. The properties and structures of II-Sn-N₂ (II = Ca, Mg, Zn) semiconductors were also systematically studied, and the differences among them were revealed by comparison. These semiconductor materials showed a rock-salt- or wurtzite-type structure depending on the combined effect of the synthetic conditions and the characteristics of the group II elements. Additionally, the rock-salt-type structures of CaSnN₂ and MgSnN₂ (i.e., the ambient-pressure phase) were different from those predicted using first-principles calculations. Further, on the basis of first-principles calculations and consideration of the pressure effect, the recovered CaSnN₂ sample showed an R3̅m structure. CaSnN₂ and MgSnN₂ showed a band gap of 2.3–2.4 eV, which is suitable for overcoming the green-light-gap problem. These semiconductors also showed a strong cathode luminescence peak at room temperature, and generalized gradient approximation (GGA) calculations revealed that CaSnN₂ has a direct band gap. These inexpensive and nontoxic semiconductors (II-Sn-N₂ semiconductors (II = Ca, Mg, Zn)), with mid band gaps are required as pigments to replace cadmium-based materials. They can also be used in emitting devices and as photovoltaic absorbers, replacing In_xGa_1–xN semiconductors.

Cyclometalated complexes containing two or more metal centers were recently shown to offer photophysical properties that are advantageous compared to their mononuclear analogues. Here we report the design, synthesis, and luminescent properties of a dinuclear Ir(III) complex formed by a ditopic N^{^}C^{^}N–N^{^}C^{^}N bridging ligand (L¹) with pyrimidine as a linking heterocycle. Two dianionic C^{^}N^{^}C terminal ligands were employed to achieve a charge-neutral and nonstereogenic dinuclear complex 5. This complex shows a highly efficient red emission with a maximum at λ_em = 642 nm as measured for a toluene solution. The decay time and emission quantum yield of the complex measured for the degassed sample are τ = 1.31 μs and Φ_PL = 80%, respectively, corresponding to the radiative rate of k_r = 6.11·10⁵ s^–1. This rate value is approximately fourfold faster than for the green-emitting mononuclear analogue 3. Cryogenic temperature measurements show that the three substrates of the lowest triplet state T₁ of 5 emit with decay times of τ(I) = 120 μs, τ(II) = 7 μs, and τ(III) = 1 μs that are much shorter compared to those of the mononuclear complex 3, which has values of τ(I) = 192 μs, τ(II) = 65.6 μs, and τ(III) = 3.6 μs. These data indicate that the spin–orbit coupling of state T₁ with the singlet states is much stronger in the case of complex 5, which results in a much higher T₁ → S₀ emission rate. Indeed, a computational analysis suggests that in the dinuclear complex 5 the T₁ state is spin–orbit coupled with twice the number of singlet states compared to that of mononuclear 3, which is a result of the electronic coupling of two coordination sites. The investigation of the temperature dependence of the emission rates of 3 and 5 shows that the room-temperature emission of both complexes is mainly contributed by a thermally populated excited state lying above the T₁ state. To the best of our knowledge, complexes 3 and 5 are the first examples of Ir(III) complexes that show photophysical behavior reminiscent of thermally activated delayed fluorescence (TADF).

Inspired by the highly efficient water oxidation of Mn₄CaO₅ in natural photosynthesis, development of novel artificial water oxidation catalysts (WOCs) with structure and function mimicked has inspired extensive interests. A novel 3D cobalt-based MOF (GXY-L8-Co) was synthesized for promising artificial water oxidation by employing the Co₄O₄ quasi-cubane motifs with a similar structure as the Mn₄CaO₅ as the core. The GXY-L8-Co not only shows good chemical stability in common organic solvents or water for up to 10 days but also exhibits oxygen evolution performance. It has been demonstrated that the uniform distribution of Co₄O₄ catalytic active sites confined in the MOF framework should be responsible for the good robustness and catalytic performance.

A convenient synthetic route has been developed for preparing the novel rigid 4,5-(PR₂)2–2,7,9,9-tetramethylacridane-based pincer ligands (^acri-RPNP; R = ⁱPr and Ph), and the first rare-earth (Ln = Y, Lu) alkyl complexes bearing the ^acri-RPNP ligands were synthesized by a salt metathesis reaction (for the isopropyl-substituent ^acri-iPrPNP complexes, 1-Ln) or direct alkylation (for the phenyl-substituent ^acri-PhPNP complexes, 2-Ln). For both 1-Ln and 2-Ln, the NMR spectroscopy and X-ray diffraction study confirmed the successful coordination of the ^acri-RPNP ligand to the central metal ion in a tridentate manner via the two phosphine and the nitrogen donors. In contrast to 1-Ln that are solvent-free complexes, the metal centers in 2-Ln are each coordinated with one tetrahydrofuran molecule. Upon activation by [Ph₃C][B(C₆F₅)₄], 1-Y and 2-Lu could catalyze the living polymerization of isoprene and β-myrcene with high catalytic activity and high cis-1,4-selectivity (up to 92.3% for isoprene and 98.5% for β-myrcene). Moreover, the 1-Y/[Ph₃C][B(C₆F₅)₄] catalytic system also could promote the polymerization of butadiene and its copolymerization with isoprene to produce copolymers with high cis-1,4-selectivity and narrow polydispersity.

An attractive catalytic pathway for the conversion of water to oxygen would involve two metal oxide centers combining in a constructive sense to make O═O. This prospect makes the study of certain dinuclear transition metal complexes particularly attractive. In this work, we describe the design and synthesis of two symmetrical bis-tridentate polypyridine ligands 6 and 12 that bind two Ru^II centers at a separation of 3.6 Å in 7 and 5.7 Å in 13. In the presence of Ce^IV at pH = 1, these systems oxidize water with the system having the more proximal metals being more reactive. In the case of the more proximal metal centers, the bridging ligand is a 3,6-disubstituted pyridazine which, under the influence of Ce^IV, cleaves into two [Ru(bpc)(pic)₂CH₃CN]⁺ fragments (14) which then function as the actual catalyst (bpc = 2,2′-bipyridine-6-carboxylate, pic = 4-methylpyridine). The second dinuclear catalyst contains a central pyrimidine ring which is less sensitive to oxidative decay and hence less reactive. Caution is advised in the use of Ce^IV as a sacrificial electron acceptor due to unexpected oxidative decay of the catalyst.

Clenbuterol (CLE) and ractopamine (RAC) are two kinds of typical β₂-adrenergic agonists which pose a serious threat to the health of human beings. In this work, 10 kinds of metal–organic frameworks (MOFs) with high stability and various pore features are screened to assess adsorption performance for CLE and RAC. An Al(III)-MOF (BUT-19) with abundant ethyl groups exhibits exceptional performance in removing CLE and RAC from water. The maximum adsorption capacity for CLE and RAC are up to 294.1 and 366.3 mg/g under the optimum adsorption conditions, respectively. Meanwhile, the adsorption mechanism effects of pH, temperature, and coexisted ions are investigated systematically. It is found that the MOF pore size and weak hydrogen-bond interactions between CLE/RAC molecules and the MOF are the main causes leading to the extraordinary adsorption. This study provides a new idea for the purposeful design and synthesis of MOFs for removing environmental pollutants and sheds light on the depuration of contaminated water.

A common challenge in Pt(IV) prodrug design is the limited repertoire of linkers available to connect the Pt(IV) scaffold with the bioactive payload. The commonly employed linkers are either too stable, leading to a linker artifact on the payload upon release, or too unstable, leading to premature release. In this study, we report the synthesis of a new class of Pt(IV) prodrugs using masked self-immolative 4-aminobenzyl linkers for controlled and traceless codrug delivery. Upon reduction of self-immolative Pt(IV) prodrugs, the detached axial ligands undergo decarboxylation and 1,6-elimination for payload release. Introduction of self-immolative linkers conferred good aqueous stability to the Pt(IV) codrug complex. Investigation revealed that efficient 1,6-elimination could be attributed to stabilization of the p-aza-quinone-methide intermediate. In particular, the self-immolative Pt(IV) prodrugs with cinnamate and coumarin derivatives were more potent than the coadministration of cisplatin with an unconjugated cinnamate or coumarin payload in vitro.

The poor water resistance property of a commercial Mn⁴⁺-activated narrow-band red-emitting fluoride phosphor restricts its promising applications in high-performance white LEDs and wide-gamut displays. Herein, we develop a structural rigidity-enhancing strategy using a novel KHF₂:Mn⁴⁺ precursor as a Mn source to construct a proton-containing water-resistant phosphor K₂(H)TiF₆:Mn⁴⁺ (KHTFM). The parasitic [HMnF₆]⁻ complexes in the interstitial site from the fall off the KHF₂:Mn⁴⁺ are also transferred to the K₂TiF₆ host by ion exchange to form KHTFM with rigid bonding networks, improving the water resistance and thermostability of the sample. The KHTFM sample retains at least 92% of the original emission value after 180 min of water immersion, while the non-water-resistant K₂TiF₆:Mn⁴⁺(KTFM) phosphor maintains only 23%. Therefore, these findings not only illustrate the effect of protons on fluoride but also provide a novel insight into commercial water-resistant fluoride phosphors.

Caprylic hydrazide ligands are ideal ligands for the synthesis of novel polynuclear metal complexes, because they contain many N,O coordination atoms with a strong coordination ability, abundant hydrogen-bond donors, acceptors, and large conjugation systems. Here, we successfully obtained one dodecanuclear cobalt nanocluster [Co^II₈Co^III₄(L1)₄(Py)₁₂(CH₃OH)₄(CH₃COO)₄]·(CH₃OH)₁₃ (1) and one octadecanuclear cobalt nanocluster [Co^II₁₈(L2)₆(Py)₄₈]·(DMF)₅·(CH₃OH)₈ (2) by using H₆L1 and H₆L2 ligands, respectively (Py = pyridine; DMF = dimethylformamide). The cyclic cobalt nanocluster 1 can be regarded as two pentanuclear cobalt units (Co₅(N–N)₄) connected by two cobalt ions, and it is a mixed-valent Co nanocluster. Every H₆L1 ligand contains 10 coordination atoms, each of which coordinates with the Co ions. And every two H₆L1 ligands form a structure similar to a handshake. The abnormal cylindrical cobalt nanocluster 2 can be regarded six trinuclear cobalt units Co₃(N–N)₂ connected by one L2^6– ligand, and every L2^6– ligand splits the structure on both sides, with a twisted cyclohexane in the middle. AC magnetic susceptibilities show that nanocluster 1 exhibits no frequency-dependent behavior, but nanocluster 2 shows an obviously single-molecule magnetic behavior, and the relaxation process of the energy barrier is 20.4 K.

A variety of methods are available to investigate the bonding in inorganic compounds. In contrast to wavefunction-based analyses, topological analysis of the electron density affords the advantage of analyzing a physical observable: the electron density. Classical topological analyses of bonding interactions within the atoms in molecules framework typically involve location of a bond path between two atoms and evaluation of a range of real-space functions at the (3, −1) critical point in the electron density that exists on that bond path. We show here that counter-intuitive trends are obtained from the analysis of the electron density (ρ), the Laplacian (∇²ρ), and ellipticity (ε) at the O–E (3, −1) critical points in the coupled-cluster singles doubles electron densities of a series of compounds featuring a range of oxygen–pnictogen bond types: EO⁺, HEO, H₂EOH, H₃EOH⁺, and H₃EO (where E = N, P, As, Sb, or Bi). If, instead, these real-space functions are evaluated along the length of the bond path, the discrepancies in the trends are resolved. We show that robust results are also obtained using electron densities from less computationally demanding density functional theory calculations. The increased computational efficiency allowed us to also investigate organic derivatives of these oxygen–pnictogen-bonded compounds and observe that the trends hold in these instances as well. We anticipate that these results will be of use to inorganic chemists engaged in the synthesis and evaluation of novel bonding interactions, particularly those involving heavy main-group elements.

New complexes of neptunyl(V) isothiocyanate with 4′-aryl-substituted 2,2′:6′,2″-terpyridines (Terpy) and N,N-dimethylacetamide (DMA) were obtained: [(NpO₂)(4′-Ph-Terpy)(DMA)(NCS)]·DMA, [(NpO₂)(4′-(4-(CF₃)C₆H₄)-Terpy)(DMA)(NCS)]·2H₂O·DMA, [(NpO₂)(4′-(3-BrC₆H₄)-Terpy)(DMA)(NCS)]·DMA, and [(NpO₂)(4′-(2-(COOH)C₆H₄)-Terpy)(DMA)(NCS)]·DMA. The structures of the compounds were determined with X-ray diffraction analysis. The neptunium coordination polyhedra were found to be pentagonal bipyramids with O atoms of the NpO₂ groups in the apical positions and the equatorial planes formed by three N atoms of the terpyridine ligand, a N atom of the isothiocyanate anion, and an O atom of DMA. The influence of the substituents of the Ar group on the crystal structure is discussed. The IR spectra contain well-resolved bands of characteristic vibrations of all groups in the complex. The electronic absorption spectra are typical for neptunium(V) complexes and contain an intense narrow absorption band belonging to an f–f transition with a maximum of 988 nm and several long-wave satellites of lower intensity. The substituted terpyridines were shown to be efficient for the extraction of various valence forms of neptunium from the isothiocyanate solutions.

A series of ionic uranyl-containing complexes, namely [C₂mim]₂[UO₂(ccnm)₄] (1), [C₄mim]₂[UO₂(ccnm)₄] (2), [N₁₁₁₁]₂[UO₂(ccnm)₄][H₂O]₂ (3), and [P₂₄₄₄]₂[UO₂(dcnm)₂(ccnm)₂] (4) [(ccnm)⁻ = carbamoylcyanonitrosomethanide; dcnm = dicyanonitrosomethanide; (C₂mim)⁺ = 1-ethyl-3-methylimidazolium; (C₄mim)⁺ = 1-butyl-3-methylimidazolium; (N₁₁₁₁)⁺ = tetramethylammonium; (P₂₄₄₄)⁺ = tributyl(ethyl)phosphonium)], were isolated from in situ formed dcnm-based ionic liquids and characterized systematically. It was found that the dcnm anions transformed into ccnm anions during the reactions. These anions coordinate with the uranyl cations in chelate or terminal monodentate coordination mode, affording negative divalent complex anions which can combine with different organic cations and form ionic uranyl-containing complexes. Plenty of C–H···O, N–H···O, C–H···N, N–H···N, and H···H weak interactions are formed in the crystal structures. The transformation of cyano to amide groups contributes to the crystallinity and leads to higher melting points as well as the luminescence quenching of these compounds.

The synthesis and structural characterization of Ae(Tp^iPr2)₂ (Ae = Mg, Ca, Sr, Ba; Tp^iPr2 = hydrido-tris(3,5-diisopropyl-pyrazol-1-yl)borate) are reported. In the crystalline state, the alkaline earth metal centers are six-coordinate, even the small Mg²⁺ ion, with two κ³-N,N′,N′′-Tp^iPr2 ligands, disposed in a bent arrangement (B···Ae···B < 180°). However, contrary to the analogous Ln(Tp^iPr2)₂ (Ln = Sm, Eu, Tm, Yb) compounds, which all exhibit a bent-metallocene structure close to C_s symmetry, the Ae(Tp^iPr2)₂ compounds exhibit a greater structural variation. The smallest Mg(Tp^iPr2)₂ has crystallographically imposed C₂ symmetry, requiring both bending and twisting of the two Tp^iPr2 ligands, while with the similarly sized Ca²⁺ and Sr²⁺, the structures are back toward the bent-metallocene C_s symmetry. Despite the structural variations, the B···M···B bending angle follows a linear size-dependence for all divalent metal ions going from Mg²⁺ to Sm²⁺, decreasing with increasing metal ion size. The complex of the largest metal ion, Ba²⁺, forms an almost linear structure, B···Ba···B 167.5°. However, the “linearity” is not due to the compound approaching the linear metallocene-like geometry, but is the result of the pyrazolyl groups significantly tipping toward the metal center, approaching “side-on” coordination. An attempt to rationalize the observed structural variations is made.

Tin oxide based materials have attracted much attention as new sources for nonlinear optical (NLO) devices, while the electronic mechanism behind the structure and nonlinearity is still unclear. In this work, by precisely controlling different functionalization ligands, here a series of binuclear [(ⁿBuSn)₂(TEOA)₂L₂] (L = monocarboxylic acid ligand) complexes have been synthesized and characterized; we also adopted a new method to make the metal clusters and PMMA blend together for NLO testing. Importantly, the electronic structure, static third-order NLO properties, sum over states (SOS) have been studied by both experimental and density function theory (DFT) analysis. The effects for general NLO polarizability under various conditions, including different substitutions ligands and replacement of the metal cores, have been further investigated. The results indicate the static second hyperpolarizabilities (γ) is inversely proportional to the band gap decreases. Notably, the theory predicts that the third-order nonlinear coefficient will double through the synergistic effects of pull–push groups. The hole–electron analysis of the main excited states indicates the simultaneous introduction of pull–push electron groups into the system cause the excitation of the valence layer from LE to LLCT, which also leads to significant increase in the γ value of complex 13. This work demonstrates that an efficient adjustment for the intensity of NLO polarizability can be achieved by regulating the substitutions and the material structures, providing a new potential for the application of tin-oxo clusters in the field of nonlinear optics.

Herein, a new series of magnetic Fe-doped CoO nanocomposites (Fe-CoO NCs) with dual enzyme-like activities (peroxidase and oxidase) were successfully synthesized. The molar ratio of Fe³⁺/Co²⁺ salts during the solvothermal process determined the morphology and catalytic activity of the NCs. Among them, the flower-like 0.15Fe-CoO NCs showed high peroxidase-mimicking activity over a wider pH range of 4–5 and a temperature range of 30–50 °C. Such nanozymes were applied for constructing a facile and sensitive colorimetric sensor to detect H₂O₂ and dopamine (DA) in the linear ranges of 6–20 and 2–10 μM with limits of detection (LODs) of 4.40 and 1.99 μM, respectively. The excellent magnetic separation performance and successful DA detection in human urine samples validated the promising application of CoO-based nanozymes in medical diagnosis. The superior catalytic behaviors of 0.15Fe-CoO NCs could be ascribed to the high surface area, open mesoporous structure, increased surface active species, and the facile redox of Fe³⁺/Fe²⁺ and Co³⁺/Co²⁺. Based on the results of the fluorescent probe and radical trapping tests, the possible mechanism that Fe doping promoted the decomposition of H₂O₂ to produce hydroxyl radical (^•OH) and superoxide radical (^•O₂^–) was proposed.

We report a detailed investigation of the coordination properties of macrocyclic lanthanide complexes containing a 3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane scaffold functionalized with four acetamide pendant arms. The X-ray structures of the complexes with the large Ln³⁺ ions (La and Sm) display 12- and 10-coordinated metal ions, where the coordination sphere is fulfilled by the six N atoms of the macrocycle, the four O atoms of the acetamide pendants, and a bidentate nitrate anion in the La³⁺ complex. The analogous Yb³⁺ complex presents, however, a 9-coordinated metal ion because one of the acetamide pendant arms remains uncoordinated. ¹H NMR studies indicate that the 10-coordinated form is present in solution throughout the lanthanide series from La to Tb, while the smaller lanthanides form 9-coordinated species. ¹H and ⁸⁹Y NMR studies confirm the presence of this structural change because the two species are present in solution. Analysis of the ¹H chemical shifts observed for the Tb³⁺ complex confirms its D₂ symmetry in aqueous solution and evidences a highly rhombic magnetic susceptibility tensor. The acetamide resonances of the Pr³⁺ and Tb³⁺ complexes provided sizable paraCEST effects, as demonstrated by the corresponding Z-spectra recorded at different temperatures and studies on tube phantoms recorded at 22 °C.

Chemical vapor deposition (CVD) of UO₂ thin films from in situ reductive decomposition using a U(VI) precursor ([U(O^tBu)₆]) was performed under applied magnetic fields (up to 1 T). The molecular mechanism responsible for the formation of U(IV) oxide was determined by nuclear magnetic resonance (NMR) analysis of gaseous byproducts revealed a reductive transformation of uranium hexakis-tert-butoxide into urania. Thin films were grown under zero-field and applied magnetic field conditions that clearly showed the guiding influence of the magnetic field on altering the morphology and crystallographic orientation of grains in UO₂ deposits produced under an external magnetic field. Application of magnetic fields was found to reduce the grain size. Whereas films with a ⟨111⟩ preferred orientation were observed under zero-field conditions, the application of magnetic fields (500 mT to 1 T) promoted a polycrystalline growth. X-ray photoelectron spectroscopy confirmed the formation of UO₂ films with traces of U(VI) centers present on the surface, which was evidently due to the surface oxidation of coordinatively unsaturated U(IV) centers, which was found to be significantly reduced in the field-assisted process. These findings emphasize the positive effect of magnetic fields on controlling the texture and chemical homogeneity of CVD-grown films. The availability of a magnetic field as an extrinsic parameter for the CVD process adds to the conventional parameters, such as temperature, deposition time, and pressure, and expands the experimental space for thin-film growth.

Photocatalytic hydrogen evolution is desired to effectively alleviate the serious crisis of energy and the environment, and the utilization of low-cost photocatalysts, especially cobalt-based MOF catalysts, is meaningful, but rarely investigated. Herein, through a self-assembly strategy, we synthesized a Co clusters-based MOF (Co₃-XL) by the ligand N,N′-bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxdiimide bi(1,2,4-triazole), containing abundant carbonyl O atoms in the channels of the 3D skeleton, and a large porosity of 50.7%. The as-synthesized MOF can be stable in the pH range of 3–10 and shows a narrow band gap of 1.82 eV. Furthermore, its maximum amount of water absorption can reach 192 cm³/g. Under irradiation of simulated solar light, the rate of hydrogen evolution is 23.05 μmol·h^–1·g^–1 among 12 h with the presence of co-catalyst Pt and photosensitizer RhB. The reaction mechanism has been probed by the transient photocurrent response and steady-state photoluminescence spectra. Therefore, as a narrow band gap photocatalyst, the cobalt clusters-based MOF (Co₃-XL) has potential applications for hydrogen evolution from water.

New CrAs-based layered mixed-anion compounds Sr₂ScCrAsO₃ (SrScO-21113) and Ba₃Sc₂Cr₂As₂O₅ (BaScO-32225) were synthesized, and their electronic structures and physical properties were investigated. The structures of these compounds comprise stacking of the anti-fluorite CrAs layer and perovskite-like SrScO or BaScO layers. The lattice constants of these compounds are relatively longer than those of the related compounds, such as BaCr₂As₂, owing to the insertion of a large perovskite blocking layer of SrScO/BaScO. While there are variations in the crystal structure of this system, such as 21113 and 32225, their chemical stability calculated by the first-principles calculations indicated that SrScO-21113 is energetically favorable compared to SrScO-32225. The formation energies of BaScO-32225 and BaScO-21113 are close to each other; in the experiment, while there was an indication of BaScO-21113 formation, only BaScO-32225 was formed as a single phase because of the low chemical stability of BaScO-21113. The partial density of states indicates that the majority of states are obtained from the 3d⁴-electrons of the Cr element hybridized modestly with p electrons at the Fermi energy. The magnetic properties of these compounds were paramagnetic, and they were different from related compounds, such as BaCr₂As₂, probably because of their long a-axis lengths. The temperature dependences of the electrical resistivities of both samples were in good agreement with the electronic band structure calculations. The variety of structures in the series of compounds with a CrAs layer results in different physical properties, and further development of new compounds may bring novel functionalities, such as superconductivity.

A comparative study has been attempted on 1-substituted 2-(pyridin-2-yl)-1H-benzo[d]imidazole ligand-coordinated copper and cobalt metal complex electrolytes Cu^+/2+[nbpbi]₂(PF₆^–)_1/2, Cu^+/2+[npbi]₂(PF₆^–)_1/2, Co^2+/3+[nbpbi]₃(PF₆^–)_2/3, and Co^2+/3+[npbi]₃(PF₆^–)_2/3 in dry acetonitrile coupled with both N3 and N719 dyes in dye-sensitized solar cell (DSSC) devices. Impressively, the copper metal sites coordinated with ligands nbpbi (L1) and npbi (L2) shift the redox potential about 190–200 mV and pave the way to achieve remarkably higher power current efficiency, which is clarified with cyclic voltammetry, electrochemical impedance spectrum, electron lifetime, and quasi Fermi-level experimental results. Overall efficiencies of 4.99, 4.82, 3.26, and 3.19% under 1 sun conditions (100 mW cm^–2) were obtained for Cu^+/2+[nbpbi]₂(PF₆^–)_1/2 and Cu^+/2+[npbi]₂(PF₆^–)_1/2 electrolytes coupled with the sensitizers (N3 and N719 dyes), which are considerably higher than those acquired for devices containing the cobalt electrolytes. These results signify a record for copper complex-based electrolytes coupled with ruthenium dyes in liquid DSSCs. In particular, bulky acceptor 4-nitro benzyl moiety-substituted 2-(pyridin-2-yl)-benzimidazole (on the N–H position) (ligand L1)-coordinated copper metal complex electrolytes achieved higher efficiency, approaching a suitable redox potential of 0.68 V versus NHE. At the same time, the napthyl moiety-substituted 2-(pyridin-2-yl)-benzimidazole (ligand L2)-coordinated copper metal complex electrolytes showed less redox potential due to its donating nature. It was determined that the J_sc and PCE increment of the devices consisting of Cu^+/2+[nbpbi]₂(PF₆^–)_1/2 electrolytes was mainly attributed to various factors such as higher chemical capacitance, larger charge, longer electron life time, a downward shift in the quasi Fermi level of TiO₂, the slow recombination process, and fast dye regeneration. These results make easily tunable metal complexes bearing a new sort of 1-substituted 2-(pyridin-2-yl)-1H-benzo[d]imidazole ligand-based electrolytes as very promising copper electrolytes for further improvements of extremely efficient liquid DSSCs.

The single-crystal X-ray diffraction characterization of cation-induced supramolecular assembly of the gallium(III) tetra(15-crown-5)phthalocyaninate [(HO)Ga(15C5)₄Pc] (1Ga) is reported. The structures of two crystalline dimers, {[(1Ga)₂Rb₄]⁴⁺(ⁱNic^–)₄}·10CDCl₃ and {[(2Ga)₂Rb₄]⁴⁺(OH^–)₂(Piv^–)₂}·16CDCl₃ (2Ga-[(Piv)Ga(15C5)₄Pc]), as well as UV–vis and NMR studies of the soluble supramolecular dimers formed by 1Ga and K⁺, Rb⁺, and Cs⁺ salts are provided. In contrast to the previously reported aluminum complex where the Al–O–Al bond was formed, no μ-oxo bridge was observed between the gallium atoms in the supramolecular dimers under similar conditions, despite the fact that aluminum and gallium belong to the same group of the periodic table. The detailed investigation of the cation-induced dimers of 1Ga confirms the uniformity of their structure for all large alkali cations, where two molecules of crown-substituted gallium phthalocyaninate are 4-fold bound by K⁺, Rb⁺, or Cs⁺. The gallium(III) coordination sphere is labile, and the nature of the solvent during supramolecular dimerization has an effect on the axial ligand exchange: Piv^– in nonpolar CHCl₃ replaces the initial OH^– in 1Ga, while such a process is not observed in CHCl₃/CH₃OH media.

Two new antimonous phosphates, namely Ba₃Sb₂(PO₄)₄ and Cd₃Sb₂(PO₄)₄(H₂O)₂, have been successfully prepared through mild hydrothermal reactions. Ba₃Sb₂(PO₄)₄ features a 1D [Sb(PO₄)₂]^3– chain structure separated by Ba²⁺ cations while Cd₃Sb₂(PO₄)₄(H₂O)₂ presents a 2D [Sb(PO₄)₂]^3– layered structure with Cd²⁺ located at the interlayer space. The [Sb(PO₄)₂]^3– chain in Ba₃Sb₂(PO₄)₄ is the first example of 1D antimonous phosphate structure, and Cd₃Sb₂(PO₄)₄(H₂O)₂ represents the first d¹⁰ transition metal antimonous phosphate. Based on UV–vis–NIR spectra, both Ba₃Sb₂(PO₄)₄ and Cd₃Sb₂(PO₄)₄(H₂O)₂ can display large optical band gaps (4.30 and 4.36 eV, respectively). But their transparent ranges are quite different because of the coordination water of Cd₃Sb₂(PO₄)₄(H₂O)₂ (500–2000 and 500–1300 nm for Ba and Cd compounds). The anhydrous Ba₃Sb₂(PO₄)₄ shows high thermal stability in the nitrogen atmosphere (900 °C). Because of the incorporation of the lone pair cation of Sb(III), the birefringence of Ba₃Sb₂(PO₄)₄ and Cd₃Sb₂(PO₄)₄(H₂O)₂ has been enhanced to 0.086 and 0.053 at 532 nm, respectively.

Recent experimental evidence suggests that the FeMoco of nitrogenase undergoes structural rearrangement during N₂ reduction, which may result in the generation of coordinatively unsaturated iron sites with two sulfur donors and a carbon donor. In an effort to synthesize and study small-molecule model complexes with a one-carbon/two-sulfur coordination environment, we have designed two new SCS pincer ligands containing a central NHC donor accompanied by thioether- or thiolate-functionalized aryl groups. Metalation of the thioether ligand with Fe(OTf)₂ gives 6-coordinate complexes in which the SCS ligand binds meridionally. In contrast, metalation of the thiolate ligand with Fe(HMDS)₂ gives a four-coordinate pseudotetrahedral amide complex in which the ligand binds facially, illustrating the potential structural flexibility of these ligands. Reaction of the amide complex with a bulky monothiol gives a four-coordinate complex with a one-carbon/three-sulfur coordination environment that resembles the resting state of nitrogenase. Reaction of the amide complex with phenylhydrazine gives a product with a rare κ¹-bound phenylhydrazido group which undergoes N–N cleavage to give a phenylamido complex.

A series of iron(IV) oxo complexes, which differ in the donor (CH₂py or CH₂COO^–) cis to the oxo group, three with hemilabile pendant donor/second coordination sphere base/acid arms (pyH/py or ROH), have been prepared in water at pH 2 and 7. The ν_Fe═O values of 832 ± 2 cm^–1 indicate similar Fe^IV═O bond strengths; however, different reactivities toward C–H substrates in water are observed. HAT occurs at rates that differ by 1 order of magnitude with nonclassical KIEs (k_H/k_D = 30–66) consistent with hydrogen atom tunneling. Higher KIEs correlate with faster reaction rates as well as a greater thermodynamic stability of the iron(III) resting states. A doubling in rate from pH 7 to pH 2 for substrate C–H oxidation by the most potent complex, that with a cis-carboxylate donor, [Fe^IVO(Htpena)]²⁺, is observed. Supramolecular assistance by the first and second coordination spheres in activating the substrate is proposed. The lifetime of this complex in the absence of a C–H substrate is the shortest (at pH 2, 3 h vs up to 1.3 days for the most stable complex), implying that slow water oxidation is a competing background reaction. The iron(IV)═O complex bearing an alcohol moiety in the second coordination sphere displays significantly shorter lifetimes due to a competing selective intramolecular oxidation of the ligand.