Assembly of Three NiII–Bis(triazole) Complexes by Exerting the Linkage and Template Roles of Keggin Anions

Three inorganic–organic hybrid compounds based on Keggin-type polyoxometalate (POM) and NiII-bis(triazole) complexes, namely, [Ni2(L1)4(SiW12O40)]·H2O (1), [Ni2(H2O)4(L2)4(HL2)2][PMo12O40]2·2H2O (2), and [Ni3(L1)5][PMo12O40]2·14H2O (3) (L1 = 1,4-bis(1,2,4-triazol-1-yl)butane, L2 = 1,6-bis(1,2,4-triazol-1-yl)hexane), have been obtained under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra, and thermogravimetric (TG) analyses. Compound 1 exhibits a (66) three-dimensional (3D) Ni-L1 framework with hexagonal channels, in which [SiW12O40]4– anions have been accommodated as tetradentate linkages. In compound 2, the Ni-L2 motif exhibits a 3D supramolecular network templated by [PMo12O40]3– (PMo12) anions. In compound 3, the Ni-L1 motif is a two-dimensional (2D) layer, which is linked by PMo12a anions to construct a 3D framework. The 3D frameworks interpenetrate with each other to form a 2-fold interpenetrating structure, which exhibits two kinds of channels. The other discrete PMo12b anions, acting as inorganic templates, are embedded in the larger channels. The Keggin anions in 3 exert not only linkage but also template roles. In addition, electrochemical properties of 1-bulk modified carbon paste electrode (1–CPE) and 3–CPE have been studied in 1 M H2SO4 aqueous solution.