Hydrothermal syntheses and structures of four new polyoxometalate based supramolecular architectures

Four new supramolecular architectures based on Keggin polyoxometalates (POMs): [(HSiMo12O40)(H4,4'-bpy)(2)][(H4,4'-bpy)(H2O)(2)]center dot 2H(2)O (1), [(HSiW12O40)(H4,4'-bpy)(2)][(H4,4'-bpy)(H2O)(2)]center dot 2H(2)O (2), [(SiW12O40) (H4,4'-bpy)(4)]center dot(4,4'-bpy)center dot 2H(2)O (3) and [H4SiW12O40](2,2'-bpy)(4) (4) (bpy = bipyridine) have been prepared hydrothermally and characterized by IR, UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), powder XRD analyses, elemental analyses, fluorescence analysis and single crystal X-ray diffraction analyses. Both compounds 1 and 2 exhibit supramolecular 2D layer structures. Compound 3 exhibits a novel supramolecular double chain structure. Compound 4 contains a 1D chain structure with two 2,2'-bpy ligands as double bridges. It should be noted that compound 4 is the first example of hybrid compound based on 2,2'-bpy ligands and POMs. (C) 2012 Elsevier B.V. All rights reserved.