Secondary organic moiety templated organic-inorganic polyoxometalate-based frameworks

Four new organic-inorganic hybrid compounds, namely, [Cu3(4,4'-bpy)3][HSiW12O40]center dot(C3H4N2) (1), [Cu-3(4,4'-bpy)(3)][PMo12O40]center dot(C5H6N2)center dot 0.5H(2)O (2), [Cu-2(4,4'-bpy)(2)][HPMo12O40]center dot(C5H6N2) (3) and [Cu(Phen)(4,4'-bpy)(H2O)](2)[PW12O40]center dot(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.