A series of POM-based hybrid materials with different copper/aminotriazole motifs

By controlling the reaction temperature, pH value of the system and the polyanion templates, three inorganic-organic hybrid materials based on Keggin polyoxometalate building blocks combined with Cu-I/II and 4-amino-1,2,4-triazole (4atrz) have been obtained by hydrothermal methods, namely, [Cu-3(mu(3)-OH)(4atrz)(6)][SiW12O40]center dot I center dot 3H(2)O (1), [Cu-4(4atrz)(6)][SiW12O40] (2) and [Cu-6(4atrz)(6)][PMo12O40](2)center dot H2O (3). Crystal structure analysis reveals that the Cu-I/II/4atrz complexes in the three materials show tri-, tetra- and hexanuclear models, respectively. In compound 2, the copper clusters link the polyoxometalates into the chains by weak Cu-O bonds; while in the compounds 1 and 3, the copper clusters and the polyoxometalates stack by the ionic interactions. These compounds are further characterized by powder XRD, elemental analyses, FT-IR and thermogravimetric (TG) analyses. The electrochemical behavior of 3-CPE has been studied in the 1 M H2SO4 solution. The results exhibit that there are four pairs of redox waves attributable to the four consecutive two-electron processes of Mo(VI/V) couples and the redox process is surface-controlled. (C) 2009 Elsevier B.V. All rights reserved.