Modified polyoxometalate: a novel monocapped bi-supporting and reduced α-Keggin structure {PMo12O40[Cu(2,2′-bpy)]}[Cu(2,2′-bpy)(en)(H2O)]2

Abstract

A novel modified polyoxometalate, {PMo12O40[Cu(2,2′-bpy)]}[Cu(2,2′-bpy)(en)(H2O)]2 [2,2′-bpy is 2,2′-bipyridyl (C10H8N2) and en is ethylenediamine (C2H8N2)], has been synthesized hydrothermally and structurally characterized by elemental analysis, TG, IR, XPS and single-crystal X-ray diffraction. The structural analysis reveals that the compound contains the reduced Keggin polyanion [PMo12O40]6− as the parent unit, which is monocapped by [Cu(2,2′-bpy)]2+ fragments via four bridging O atoms on an {Mo4O4} pit and bi-supported by two [Cu(2,2′-bpy)(en)(H2O)]2+ coordination cations simultaneously. There exist strong intramolecular π–π stacking between the capping and supporting units, which play a stabilizing role during the crystallization of the compound. Adjacent POM clusters are further aggregated to form a three-dimensional supramolecular network through noncovalent forces, hydrogen bonding and π–π stacking interactions. In addition, the photocatalytic properties were investigated in detail, and the results indicated that the compound can be used as a photocatalyst towards the decomposition of the organic pollutant methylene blue (MB).