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 CuI/II and 4-amino-1,2,4-triazole (4atrz) have been obtained by hydrothermal methods, namely, [Cu3(μ3-OH)(4atrz)6][SiW12O40]·I·3H2O (1), [Cu4(4atrz)6][SiW12O40] (2) and [Cu6(4atrz)6][PMo12O40]2·H2O (3). Crystal structure analysis reveals that the CuI/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.