Syntheses, crystal structures and properties of inorganic–organic hybrids constructed from Keggin-type polyoxometalates and silver coordination compounds

Abstract

Four inorganic–organic hybrids based on polyoxometalates (POMs), [Ag₄(btz)₂(Hbtz)₂(H₂O)Na(PMo₁₂O₄₀)·H₂O] (1), [Ag₂(4,4′-bpy)₂Ag₂(4,4′-bpy)(H₂O)₂(PMo^VMo^VI₁₁O₄₀)] (2), [Ag₅(btz)₂(4,4′-bpy)₂(PMo₁₂O₄₀)·3H₂O] (3), and [Ag₅(btz)₂(4,4′-bpy)₂(PW₁₂O₄₀)·3H₂O] (4) (Hbtz = 1H-1,2,3-benzotriazole, 4,4′-bpy = 4,4′-bipyridine), have been hydrothermally synthesized and structurally characterized by conventional techniques. Compound 1 is a 2D layer composed of Ag^I ions, btz ligands and [PMo₁₂O₄₀]³⁻ anions. Compound 2 represents a rare 3D poly-threading framework based on infinite 2D layers made up of {POM–Ag₂} inorganic building blocks and bpy ligands, which were threaded by silver–organic linear double chains. Compounds 3 and 4 are isostructural and exhibit three-fold interpenetrating diamondoid frameworks containing tri-nuclear silver centers as nodes and hexa-nuclear silver–organic macrocycles and [PMo₁₂O₄₀]³⁻ anions, both as bi-connected units. Furthermore, their electrochemical properties, fluorescence properties and optical band gaps have been investigated in detail.