Secondary organic moiety templated organic–inorganic polyoxometalate-based frameworks

Abstract

Four new organic–inorganic hybrid compounds, namely, [Cu₃(4,4′-bpy)₃][HSiW₁₂O₄₀]·(C₃H₄N₂) (1), [Cu₃(4,4′-bpy)₃][PMo₁₂O₄₀]·(C₅H₆N₂)·0.5H₂O (2), [Cu₂(4,4′-bpy)₂][HPMo₁₂O₄₀]·(C₅H₆N₂) (3) and [Cu(Phen)(4,4′-bpy)(H₂O)]₂[PW₁₂O₄₀]·(4,4′-bpy) (4) (C₃H₄N₂ = imidazole, C₅H₆N₂ = 2-aminopyridine, bpy = bipyridine, Phen = 1,10-phenanthroline), have been synthesized and characterized by IR, UV-vis, powder XRD, cyclic voltammetry analysis, photoluminescence analysis, elemental analyses and single crystal X-ray diffraction. The four compounds represent new examples of secondary organic moiety templated frameworks constructed from Keggin polyanions, metal ions and organic ligands. Compounds 1 and 2 present 3-D framework structures; compound 3 exhibits a 1-D ladder-like structure and compound 4 shows a 2-D layered framework structure. It is noted that the packing structures of compounds 1 and 2 are almost identical; however, the crystal space groups and cell parameters of the two are thoroughly different. Such a phenomenon has also been observed between compound 3 and a compound recently reported by us. Compound 4 is the first framework structure constructed from polyoxometalates, metal ions and mixed organic ligands. In addition, all the four frameworks are combined with dissociated organic moieties as templates.