Inorganic Chemistry最新文献

Transition-metal-based metal-organic frameworks (MOFs), especially Ni-MOFs, have emerged as attractive candidates for electrochemical energy storage owing to their considerable theoretical specific capacitance. However, their poor electrical conductivity severely limits the overall electrochemical performance in supercapacitors. By virtue of the excellent conductivity of conductive MOFs (cMOFs), in this work, a series of MOF-on-MOF heterostructures were fabricated by integrating cMOFs M-HHTP (M = Ni, Co; HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) with Ni-MOFs (Ni-BTC, Ni-BDC; H₃BTC = trimesic acid, H₂BDC = terephthalic acid). Electrochemical tests reveal that all of the composites exhibit enhanced energy storage performance compared to that of the pristine MOFs, with Co-HHTP@Ni-BDC demonstrating the most outstanding performance in the application of aqueous asymmetric supercapacitors.

The molecular design of coordination polymers (CPs) and metal-organic frameworks (MOFs) has attracted increasing attention in the areas of inorganic chemistry and functional materials. In this study, a new series of 2D CPs and 3D MOFs was hydrothermally assembled from metal(II) chlorides and 2,2'-((4-carboxy-1,2-phenylene)bis(oxy))diacetic acid (H₃cpbda) as a flexible and little-explored tricarboxylate linker. Additionally, several types of aromatic N,N-donor auxiliary ligands were used to promote crystallization, namely, 1,10-phenanthroline (phen), 4,4'-bipyridine (bipy), bis(4-pyridyl)amine (bpa), 1,2-di(4-pyridly)ethylene (dpey), or 1,2-di(4-pyridly)ethane (dpea). The obtained products were fully characterized and identified as [M₃(μ₆-cpbda)₂(phen)₂]_n·4nH₂O (M = Zn (1), Cd (2)), [Co₃(μ₅-cpbda)₂(μ-bipy)₂]_n·2nH₂O (3), [Zn₃(μ₅-cpbda)₂(μ-bipy)₂]_n (4), [Zn(μ₃-cpbda)(Hbpa)]_n·4nH₂O (5), [Zn₄(μ₃-cpbda)₂(μ-OH)₂(μ-dpey)₃(H₂O)₂]_n·2nH₂O (6), [Co₃(μ₄-cpbda)₂(μ-dpey)₃]_n·2nH₂O (7), and [Ni₃(μ₄-cpbda)₂(μ-dpea)₃]_n·2nH₂O (8). Their structural and topological features were also explored, allowing us to identify a diversity of 2D and 3D coordination networks. Remarkably, Zn-based coordination polymers 5 and 6 revealed a high catalytic activity and reusability in the condensation reaction between benzaldehyde and malononitrile (or ethyl cyanoacetate), leading to almost quantitative product yields (99%) under optimized conditions. The present work contributes to widening the family of CPs/MOFs assembled from flexible polycarboxylate linkers and highlights a promising application of these compounds in heterogeneous catalysis.

This work presents a new family of zincacarborane complexes synthesized from ZnMe₂ and [C₂B₉H₁₃], using neutral two-electron donor ligands: N-heterocyclic carbenes (NHCs) yield the first closo-12-vertex half-sandwich zincocenes, [(NHC)Zn(C₂B₉H₁₁)] (1-3), while bulkier NHCs form slipped bis-dicarbollide salts (4-5). Use of pyridine leads to the macropolyhedral dimer (6) with a planar {Zn₂B₂} motif, and triphenylphosphine gives a V-shaped η³-borallyl complex (7). Structures have been confirmed by single-crystal X-ray diffraction and NMR spectroscopy. Computational studies (DFT and QTAIM) show predominantly ionic Zn-dicarbollide bonding with notable polar covalent character. Apparent Zn···Zn interactions are weak electrostatic contacts, and metal-ligand bonding is exclusively to boron atoms. Together, these findings broaden the structural and electronic landscape of zincacarboranes, challenge assumptions about d¹⁰ metal-carborane bonding, and offer a new platform for exploring group 12 metallacarborane reactivity.

The phase transition sequences of MeX₂ compounds (Me = metal or, more generally, an electropositive element), whose constituent atoms contribute 16 valence electrons per formula unit under high pressure, are of fundamental importance in materials science, high-pressure chemistry, and mineral physics. Here, we report the first observation of trigonal prismatic coordination in this class of materials, realized in magnesium dichloride MgCl₂. We synthesized anhydrous MgCl₂ by the direct reaction of elemental magnesium with carbon tetrachloride (CCl₄) in laser-heated diamond anvil cells from 7(2) to 83(3) GPa. Single-crystal X-ray diffraction identified the known hP3-MgCl₂ polymorph at 7(2) GPa, and two previously unknown high-pressure phases: an orthorhombic oP72-MgCl₂ at 28(2) and 44(3) GPa, and a cotunnite-type oP12-MgCl₂ at 64(3), 73(3), and 83(3) GPa. The oP72 phase features distorted MgCl₆ trigonal prisms, while the oP12 phase adopts MgCl₈ bicapped trigonal prisms. This sequence of hP3 → oP72 → oP12 reveals a complex pressure-induced structural transition from layered to three-dimensional frameworks. Ab initio calculations agree well with the experimental structural data, support the stability range of the new polymorphs, provide the equation of states, and reveal their electronic properties. Our findings demonstrate several transformation pathways by which MeX₂ compounds evolve toward cotunnite-type structures under compression.

The development of efficient and cost-effective catalysts for CO₂ electroreduction is of great significance for sustainable carbon utilization. Here, we report a novel Ag-coated Ga core-shell (Ga@Ag) catalyst synthesized via chemical reduction deposition, where the Ga core provides electronic modulation and the Ag shell offers abundant active sites. Structural characterizations confirm the formation of a uniform Ga(core)/Ag(shell) architecture with intimate interfacial contact, which enables strong electron coupling between Ag and Ga. Electrochemical measurements in an organic tetrabutylammonium chloride (Bu₄NCl)/acetonitrile (AN) electrolyte demonstrate that Ga@Ag exhibits a more positive onset potential, a higher CO partial current density, and a remarkable Faradaic efficiency for CO production (92.3%) at -2.4 V (vs SHE), significantly surpassing Ag powder. This work reveals that interfacial electron coupling in Ga@Ag catalysts effectively promotes CO₂ activation and enhances CO selectivity, providing new insights into the rational design of core-shell electrocatalysts for efficient CO₂-to-CO conversion under organic electrolyte conditions.

The structural stability of CoSbS under extremely high-pressure conditions was investigated by using in situ high-pressure X-ray diffraction. Remarkably, CoSbS demonstrates exceptional structural stability even at ∼60 GPa. Building upon these stable structural characteristics, we employed first-principles calculations and Boltzmann transport theory to analyze the electronic structure and thermoelectric properties of CoSbS under high pressure. The study reveals that pressure significantly modifies the electronic structure of CoSbS, leading to a progressive reduction in the band gap, pronounced energy band convergence near the conduction band minimum, and a substantial decrease in carrier effective mass. Simultaneously, the synergistic interaction between heavy and light bands under high pressure induces concurrent enhancement of electrical conductivity and preservation of the high Seebeck coefficient. This cooperative effect yields an exceptional power factor of 88 μW cm^-1 K^-2. Unfortunately, under high pressure, the reduction in phase space and Grüneisen parameter during three-phonon scattering, combined with increased phonon specific heat and relaxation time, diminishes the anharmonic scattering effect of phonons in CoSbS, leading to an increase in the lattice thermal conductivity. The results demonstrated that high-pressure regulation could optimize the electrical transport properties of materials, offering valuable insights for exploring other thermoelectric materials and elucidating the influence of high pressure on the thermal transport properties.