Hydrothermal synthesis, crystal structure and electrochemical properties of a novel 3D Dawson-type polyoxometalate supramolecular network

A novel Dawson-type polyoxometalate supramolecular architecture of the formula [4,4′-H 2 bipy] 2.5 ·[4,4′-Hbipy]·[P 2 W 18 O 62 ]·6.25H 2 O (4,4′-bipy = 4,4′-bipyridine) has been hydrothermally synthesised and characterised by means of elemental analysis, IR, CV and X-ray single-crystal diffraction. X-ray crystallography indicates that the title compound consists of Dawson-type polyoxoaions [P 2 W 18 O 62 ] 6- , water molecules and 4,4′-bipy units. The polyoxoanion clusters together with 4,4′-bipy units and water molecules to construct the three-dimensional supramolecular network through hydrogen bonds. The crystal structure analyses reveal that water molecules and 4,4′-bipy units play the important role on the packing arrangements of crystals. Cyclic voltammetry shows that the title compound exhibits three chemically reversible steps