Hydrothermal syntheses, crystal structures, and properties of two polyoxometalates [Cd(2,2′-bpy)3]2[PMoVMoVI 11O40] and [H3PMo12O40]·3(4,4′-bpy)·4H2O

Abstract

Two Keggin-type phosphododecamolybdate compounds [Cd(2,2′-bpy)3]2[PMoVMoVI 11O40] (1) and [H3PMo12O40]·3(4,4′-bpy)·4H2O (2) (bpy=bipyridine) were prepared by the hydrothermal method for the first time and characterized by elemental analyses, X-ray single-crystal diffraction, ESR spectra, and IR spectra, showing that compound 1 consists of a mixed valence Keggin polyanion [PMoVMoVI 11O40]4− and two isolated coordinated cations [Cd(2,2′-bpy)3]2+, while compound 2 is an intermolecular compound based on organic substrate 4,4′-bpy and heteropoly acid unit H3PMo12O40. Furthermore, both the compounds show strong photoluminescence properties in the solid state at room temperature. The catalytic activities of the two compounds were also determined by the oxidation of benzaldehyde to benzoic acid using H2O2 as oxidant in a liquid–solid triphase system.