Hydrothermal syntheses and structures of two novel polyoxometalate-based 3-D supramolecular architectures

Abstract

Two supramolecular architectures based on polyoxometalates: [4,4′-Hbpy] 2[Ni(4,4′-bpy) 2(H 2O) 4][AsW VI 11W VO 40]·4H 2O ( 1) and [4,4′-H 2bpy] 2[PMo VI 9Mo V 3O 40]·2H 3O ( 2) (4,4′-bpy = 4,4′-bipyridine) have been prepared under hydrothermal conditions and characterized by elemental analyses, IR spectra, XPS spectra and single crystal X-ray diffraction analyses. The two compounds consist of 4,4′-bpy units with different polyoxometalates, α-Keggin [AsW VI 11W VO 40] 4− and pseudo-Keggin [PMo VI 9Mo V 3O 40] 6−, respectively. No direct interactions occur among polyoxoanions in these two compounds, but the clusters together with metal-organic units or organic 4,4′-bpy units and/or water molecules construct the high-dimensional supramolecular networks through hydrogen bonds. The crystal structure analyses reveal that the organic 4,4′-bpy units have a major influence on the packing arrangements of crystals.