Inorganic Chemistry最新文献

Porous metal-organic frameworks (MOFs) have shown great potential as adsorbents for capturing radioiodine, a major fission product generated during the reprocessing of nuclear fuel. However, studies exploring the correlation between the structure of MOFs and iodine uptake capacity remain notably rare. In this study, we introduce a new strategy for enhancing the iodine adsorption efficiency of MOFs by strategically varying the position of functional groups on the organic linkers. Employing ligand-functionalized UiO-67 MOFs, our findings reveal that ortho-amino substitution of UiO-67-o-NH₂, proximal to the node of the dicarboxylate linker, markedly accelerates adsorption kinetics of iodine vapor in comparison to meta-amino substitution of UiO-67-m-NH₂, where the amino groups are oriented away from the node. In contrast, UiO-67-m-NH₂ exhibits a higher adsorption capacity of 2.19 g/g, compared to 1.91 g/g for UiO-67-o-NH₂, attributable to its higher porosity. Furthermore, a competitive I₂/H₂O vapor adsorption study demonstrated that UiO-67-o-NH₂ exhibits faster adsorption kinetics and higher selectivity for iodine in the presence of water vapor compared to UiO-67-m-NH₂. Additionally, the crucial influence of positional isomerism on enhancing iodine adsorption has been corroborated through Raman spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. These analyses reveal that the nitrogen atom positioned at the ortho site demonstrates a stronger affinity for iodine molecules compared to the nitrogen atom at the meta site, thereby improving adsorption kinetics.

We present a detailed investigation of the coordination chemistry toward [^natCu/⁶⁴Cu]copper of a series of H₂DEDPA derivatives (H₂DEDPA = 6,6'-((ethane-1,2-diylbis(azanediyl))bis(methylene))dipicolinic acid) containing cyclohexyl (H₂CHXDEDPA), cyclopentyl (H₂CpDEDPA) or cyclobutyl (H₂CBuDEDPA) spacers. Furthermore, we also developed a strategy that allowed the synthesis of a H₂CBuDEDPA analogue containing an additional NHBoc group at the cyclobutyl ring, which can be used for conjugation to targeting units. The X-ray structures of the Cu(II) complexes evidence distorted octahedral coordination around the metal ion in all cases. Cyclic voltammetry experiments (0.15 M NaCl) evidence quasi-reversible reduction waves associated with the reduction of Cu(II) to Cu(I). The complexes show a high thermodynamic stability, with log K_CuL values of 25.11(1), 22.18(1) and 20.19(1) for the complexes of CHXDEDPA^2-, CpDEDPA^2- and CBuDEDPA^2-, respectively (25 °C, 1 M NaCl). Dissociation kinetics experiments reveal that both the spontaneous- and proton-assisted pathways operate at physiological pH. Quantitative labeling with ⁶⁴CuCl₂ was observed at 0.1 nmol for CHXDEDPA^2- and CpDEDPA^2-, 0.025 nmol for CBuDEDPA^2- and 1 nmol for CBuDEDPA-NHBoc^2-, with no significant differences observed at 15, 30, and 60 min. The radio-complexes are stable in PBS over a period of 24 h.

Stable porous manganese oxide-based electrodes are essential for clean energy generation and storage because of their high natural abundance and health safety. This investigation focuses on mesoporous LiMn_2-xM_xO₄ (where M is Fe, Co, Ni, and Cu and x is 0, 0.1, 0.3, 0.5, and 0.67) electrodes and thin/thick films. The mesoporous electrodes and films are fabricated by coating clear and homogeneous ethanol solutions of the salts (LiNO₃, [Mn(OH₂)₄](NO₃)₂, and [M(OH₂)_x](NO₃)₂) and surfactants (P123 and CTAB) and calcining at elevated temperature (denoted as F-LiMn_2-xM_xO₄, G-LiMn_2-xM_xO₄, and meso-LiMn_2-xM_xO₄, respectively). The electrochemical properties, stability, and oxygen evolution reaction (OER) performance of the F/G-LiMn_2-xM_xO₄ electrodes are investigated in alkaline media using a three electrode setup. The F-LiMn_1.33M_0.67O₄ electrodes (where M is Mn, Fe, Co, and Ni) exhibit low Tafel slopes of 60, 43, 44, and 32 mV/dec, respectively. While all the Mn-rich and F-LiMn_2-xFe_xO₄ electrodes degrade via Mn(VI) disproportionation reaction, the 33% Co electrode shows high stability during the OER. The nickel-based electrodes are stable with as little as 15% Ni and display excellent OER performance over 25% Ni, albeit undergoing a transformation that accumulates Ni(OH)₂ species on the electrode surface. Copper in the F-LiMn_2-xCu_xO₄ electrodes is homogeneous at low Cu percentages but forms a CuO phase above 15% Cu, undergoes degradation, and displays a weak OER performance. In short, Co and Ni stabilize the F-LiMn_1.33Co_0.67O₄ and F-LiMn_1.7Ni_0.3O₄ electrodes, which display excellent OER performance.

The synthesis of a series of [4]rotaxanes, each consisting of three [2]rotaxanes joined via a central {CrNi₂} triangular linker, is reported. The resultant four [4]rotaxanes were characterized by single crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopy. Orientation-selective 4-pulse double electron-electron resonance (DEER) measurements between the three {Cr₇Ni} rings incorporated in each [4]rotaxane reveal that each system is conformationally fluxional in solution, with the most abundant conformations found to differ significantly from the crystal structure geometry for each compound. The degree of similarity between conformations is evaluated using a novel application of the earth mover's distance analysis.

Metal-organic frameworks (MOFs) with a large number of active sites and high porosity are considered to be good platforms for the carbon dioxide electroreduction reaction (CO₂RR) but with confined low conductivity or low efficiency. Here, Pd-[Bmim]PF₆/Cu-BTC with exceptional selectivity and electron-transfer ability is elaborately designed by introducing ionic liquids (ILs) into the MOFs. ILs favor promoting the overall current density of the catalysts, and the introduction of Pd atoms combined with O atoms on the catalyst surface reconfigures into strong Pd-O bonds, improving the desorption efficiency of *CO. The unique structure of the catalyst Pd-[Bmim]PF₆/Cu-BTC leads to a significant improvement of the C₁ product with a high Faraday efficiency (FE) of 99.36%, especially for carbon monoxide (CO) with an FE of 93.18% (-1.1 V_RHE). The exceptional performance of the catalyst is verified by density functional theory (DFT) calculations, and the reduction of the free energy required by *HOCO as a key intermediate for CO production was only 0.12 eV, providing new insights to improve the electrocatalytic performance of MOF-based materials for the CO₂RR. In this research, an effective and promising strategy that configures active sites by larger current density is proposed to enhance the efficiency of the CO₂RR.

Sodium ion capacitors (SICs) are promising candidates in energy storage for their remarkable power and energy density. However, the inherent disparity in dynamic behavior between the sluggish battery-type anodes and the rapid capacitor-type cathodes constrained their performance. To address this, we fabricated a hollow porous Co_0.85Se/ZnSe@MXene anode featuring multiheterostructure, utilizing facile etching and electrostatic self-assembly strategies. The hollow porous structure and multiple heterointerfaces stabilize the anode by mitigating the volume changes. Density functional theory (DFT) calculations further revealed that induced multilevel built-in electric fields facilitate the formation of rapid ion diffusion pathways and reduce the Na⁺ adsorption energy, thereby boosting Na⁺/electron transport kinetics. The fabricated TA-Co_0.85Se/ZnSe@MXene anode demonstrates outstanding long-term cycling stability of 406 mA h g^-1 after 1000 cycles at 1 A g^-1, with an ultrahigh rate performance of 288 mA h g^-1 at 10 A g^-1. When paired with the active carbon (AC) cathode, the SICs deliver extraordinary energy/power densities of 144 W h kg^-1 and 12000 W kg^-1, maintaining over 80% capacity retention at 1 A g^-1 after 10000 cycles. This innovative strategy of engineering multiheterostructured anode with the induced multilevel built-in electric fields holds significant promise for advancing high-energy and high-power energy storage systems.

Prussian blue analogues (PBAs) are a highly tunable family of materials with properties suitable for a wide variety of applications. Although their straightforward aqueous synthesis allows for the facile preparation of a diverse set of compositions, the use of water as the solvent has hindered the preparation of specific compositions with highly sought-after properties. A typical example is Cr[Cr(CN)₆]: its predicted strong magnetic interactions have motivated many attempts at its synthesis but with limited success. The lack of control over vacancies, crystallinity, and the oxidation state has prevented the experimental validation of its theoretical magnetic properties. Here, we report the nonaqueous synthesis of vacancy-suppressed, nanocrystalline chromium hexacyanochromate. The control over vacancies and the oxidation state leads to stronger magnetic interactions with a markedly increased absolute Weiss temperature (Θ = -836(6) K) and magnetic ordering temperature of (240 ± 10) K. Our results challenge the notion of the solvent as merely reaction medium and introduce a pathway for exploring moisture- and air-sensitive PBA compositions.

Cu-mediated Ullmann-type coupling reactions are fundamental to organic synthesis, garnering significant academic and industrial interest since their inception. Optimizing reaction parameters, particularly temperature control, is crucial for maximizing efficiency while maintaining high yields. Bidentate ligands, such as amino acids, have demonstrated potential in facilitating these reactions at lower temperatures (<100 °C). This study explores the Cu-catalyzed Ullmann-type coupling of naphthalimide derivatives with amino acid substitutions. Naphthalimide dyes, known for their diverse applications in bioimaging, solar cells, medicine, and sensors, were selected for their potent anticancer properties. The synthesized compounds were characterized by using ¹H NMR, ESI-MS, and melting point analyses. Compounds with significant steric hindrance exhibited lower yields, leading to the development of a novel catalytic system employing l-carnosine as a bidentate ligand, which significantly improved yields. Mechanistic insights, derived from density functional theory calculations, identified "L-complex 3" as the most stable and reactive intermediate during oxidative addition to aryl halides. The oxidative addition transition state "OX1-TS" was found to be the most favorable, with a relatively low energy barrier of 6.13 kcal/mol, suggesting that this step, despite being the rate-limiting stage, is energetically accessible. In contrast, reductive elimination was facilitated by a Cu(III) penta-coordinated intermediate, with a barrier of just 8.34 kcal/mol, making it a more straightforward process. Theoretical findings aligned closely with experimental data, reinforcing the oxidative addition/reductive elimination pathway as the operative mechanism for this reaction.

Bidentate Pt(II) complexes with cyclometalated N-heteroarene or N-heterocyclic carbene (NHC) ligands have been extensively studied as phosphorescent emitters over the past two decades. Herein, we introduce a difluoromethyl group (CF₂H) into the wingtip of NHCs, where CF₂H acts as a lipophilic hydrogen bond (HB) donor. Their cyclometalated Pt(II) complexes show excellent PLQYs (up to 93%) and phosphorescence lifetimes mainly due to the rigid structure with hydrogen bonding between the CF₂H group and the adjacent O atom at the β-diketonate ligand. Bioimaging studies demonstrate high cellular uptake efficiency and deep tumor penetration capability of complex 7 in HeLa cells and multicellular tumor spheroids, highlighting their potential as bioimaging probes.