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]·2H2O (1), [(HSiW12O40)(H4,4′-bpy)2][(H4,4′-bpy)(H2O)2]·2H2O (2), [(SiW12O40)(H4,4′-bpy)4]·(4,4′-bpy)·2H2O (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.