Syntheses, Structures And Properties Of Inorganic-organichybrids Based On Keggin-type Polyoxometalates

Polyoxometalates（POMs）, as an important family of metal oxides, have long been of intense scientific and technological interest, particularly in the field of catalysis, electrochemistry, magnetism, and medicine. In this paper, we chose multifunctional N-heterocycle ligands as well as Ag ions to decorate the POMs,a series of novel high-dimensional POM-based hybrids have been synthesized,they have been structurally characterized by single-crystal X-ray diffraction, IR, TG, and UV-vis absorption spectra. Furthermore, their electrochemical properties, fluorescence properties and optical band gaps have been investigated.1. Under hydrothermal conditions, we use [PMo12O40]3- and [PW12O40]3- as reactant, and chose multifunctional N-heterocycle ligands 1-H-1,2,3-benzotriazole（Hbtz） or（and） 4,4’-bipyridine as well as Ag ions to investigate the effect of mixed ligands on the formation of POMs-based hybrids. Four novel high-dimensional POM-based inorganic-organic hybrids have been successfully obtained. In compound 1, the combination of AgI ions, btz and [PMo₁2O₄0]₃- anions leads to a 2D layer. Compound 2 possesses a 3D poly-threading framework containing {Ag–（4,4’-bpy）} chains and {POM–Ag₂}–bpy layers. Compound 3 and 4 are iso-structural and exhibit three-fold interpenetrating diamondoid 3D frameworks. Their electrochemical properties, fluorescence properties and optical band gaps have been investigated.[Ag₄（btz）₂（Hbtz）₂（H₂O）Na（PMo₁2O₄0）·H₂O]（1）[Ag₂（4,4’-bpy）₂Ag₂（4,4’-bpy）（H₂O）₂（PMoVMoVI₁1O₄0）]（2）[Ag₅（btz）₂（4,4’-bpy）₂（PMo₁2O₄0）·3H₂O]（3）[Ag₅（btz）₂（4,4’-bpy）₂（PW₁2O₄0）·3H₂O]（4）2. Under hydrothermal conditions, we chose [SiW₁2O₄0]₄- polyanion, Ag ions and pz ligands as reactant to construct a novel POM-based inorganic-organic hybrid 5. In compound 5, there are two identical interpenetrating 3D frameworks containing deca-nuclear silver circles and pz ligands, which are further linked by [SiW₁2O₄0]₄-anions to exhibit an entangled architecture. Additionally, its optical band gap, photocatalytic performance and electrochemical behavior at room temperature have been investigated.[Ag₄（pz）₆（SiW₁2O₄0）·H₂O].（5）...