An Effective Strategy To Construct Novel Polyoxometalate-Based Hybrids by Deliberately Controlling Organic Ligand Transformation In Situ

Deliberately controlling organic ligand transformation in situ has remained a challenge for the construction of polyoxometalate (POM)-based inorganic–organic hybrids. In this work, four POM-based hybrids assembled from an in situ bifurcating organic ligand[Cu2(DIBA)4]­(H3PMo12O40)·6H2O (1), [Cu2(DIBA)4]­(H4SiW12O40)·6H2O (2), [Ag­(HDIBA)2]­(H2PMo12O40)·2H2O (3), [Ag3(HDIBA)2(H2O)]­[(P2W18O62)1/2]·4H2O (4) (DIBAH = 3,5-di­(1H-imidazol-1-yl) benzoic acid)have been designed and obtained under hydrothermal conditions. Compounds 1 and 2 are isostructural, displaying a three-dimensional (3D) 2-fold interpenetrating framework with two types of channels, and the bigger channels are occupied by Keggin polyoxoanions and crystallization water molecules, but only crystallization water molecules in the smaller ones. Compound 3 displays a 3D supramolecular structure constructed from {Ag­(HDIBA)2} segments and PMo12O403– polyoxoanions through hydrogen bonding interactions. Compound 4 shows a 3D 2-fold interpenetrating framework based on (3, 3, 4)-connected network, which is constructed from {Ag3(HDIBA)2}n chains and P2W18O626– polyoxoanions as linkers. The DIBAH ligand was generated in situ from 3,5-di­(1H-imidazol-1-yl)­benzonitrile by deliberate design, which illustrates that the strategy to construct novel POM-based hybrids by controlling ligand transformation in situ is rational and feasible. In addition, the effects of the central metal and POMs on the structures of the target compounds were discussed. Finally, the electrochemical and photocatalytic properties of compounds 1–4 have been investigated in this paper.在构建基于多金属氧酸盐（polyoxometalate, POM）的无机-有机杂化材料过程中，实现有机配体的原位可控转化始终是一项挑战性课题。本研究通过原位分叉型有机配体组装得到了四种POM基杂化材料，分别为[Cu₂(DIBA)₄](H₃PMo₁₂O₄₀)·6H₂O (1)、[Cu₂(DIBA)₄](H₄SiW₁₂O₄₀)·6H₂O (2)、[Ag(HDIBA)₂](H₂PMo₁₂O₄₀)·2H₂O (3)以及[Ag₃(HDIBA)₂(H₂O)][(P₂W₁₈O₆₂)₁/₂]·4H₂O (4)（DIBAH = 3,5-二(1H-咪唑-1-基)苯甲酸），所有产物均在水热条件下合成得到。 化合物1与2为同构体，均呈现出三维（3D）二重互穿框架结构，包含两种类型的孔道：较大孔道被Keggin型多金属氧阴离子（Keggin polyoxoanions）与结晶水分子占据，而较小孔道仅填充结晶水分子。化合物3呈现出三维超分子结构，由{Ag(HDIBA)₂}结构单元与PMo₁₂O₄₀³⁻多金属氧阴离子通过氢键相互作用构筑而成。化合物4则基于(3,3,4)-连接网络构建出三维二重互穿框架，该框架由{Ag₃(HDIBA)₂}ₙ链状结构与作为连接体的P₂W₁₈O₆₂⁶⁻多金属氧阴离子共同组装得到。 本研究通过精心设计，使3,5-二(1H-咪唑-1-基)苯甲腈原位转化得到DIBAH配体，这证实了通过调控配体原位转化策略构建新型POM基无机-有机杂化材料的合理性与可行性。此外，本研究还探讨了中心金属离子与多金属氧酸盐种类对目标化合物结构的影响。最后，本文对化合物1至4的电化学与光催化性能进行了系统研究。