Three metal-organic networks based on Keggin-type polyoxometalates (POMs) have been hydrothermally synthesized by tuning the spacer lengths of bis(tetrazole)-functionalized thioether ligands and structurally characterized: [Cu(4)(bmtm)(4)][SiW(12)O(40)]·2H(2)O (1), [Cu(4)(bmte)(3.5)][SiW(12)O(40)] (2), and [Cu(4)(bmtp)(4)][SiW(12)O(40)] (3) [bmtm = 1,1'-bis(1-methyl-5-mercapto-1,2,3,4-tetrazole)methane, bmte = 1,2-bis(1-methyl-5-mercapto-1,2,3,4-tetrazole)ethane, and bmtp = 1,5-bis(1-methyl-5-mercapto-1,2,3,4-tetrazole)pentane]. The spacer lengths and sulfhydryl of bis(tetrazole)-functionalized thioether ligands play important roles in the final framework formation, as shown by X-ray diffraction analysis. In compound 1, with the connection of a N,S bridge of bmtm, two kinds of binuclear Cu(I) units are formed and linked to construct a one-dimensional (1D) chain. The [SiW(12)O(40)](4-) (SiW(12)) cluster provides four terminal O atoms linking four binuclear units to generate a two-dimensional layer with (8(3))(2)(8(5)·10) topology. In compound 2, centrosymmetric octameric moieties composed of two equivalent tetrameric Cu(I) units are bridged by bmte ligands to form a 1D chain. The SiW(12) clusters show an unusual (2,8)-connected mode to connect with the 1D chain and construct a four-connected three-dimensional (3D) network with 5(3)·6(2)·7 topology. Compound 3 exhibits a rare 3D host framework with a type of large cavity and two types of small windows. The SiW(12) clusters as templates are strongly cemented into the large cavities and completely encircled by small windows. Furthermore, the compound 2 bulk-modified carbon-paste electrode (2-CPE) displays good electrocatalytic activity toward the reduction of nitrite.

A novel (3,4)-connected 3D self-penetrating metal-organic framework with a nanometre-scale cavity constructed from metallacalix[4]arene building blocks and Keggin-type polyanions has been obtained by using a 1,3-bis(1-methyl-5-mercapto-1,2,3,4-tetrazole)propane ligand.

Four inorganic−organic hybrids based on Keggin-type polyoxometalate (POM), [Ag3(bmte)2(PMo12O40)] (1), [CuI 3(bmte)3(PMo12O40)] (2), [CuII(bmte)3(HPMo12O40)] (3), and [Ni(bmte)3(HPMo12O40)] (4) (bmte = 1,2-bis(1-methyl-5-mercapto-1,2,3,4-tetrazole)ethane), have been synthesized under hydrothermal conditions by tuning the coordination nature of transition metal (TM) ions. The transformation of coordination modes of TM ions has a crucial influence on the multinuclear structures of this series. In compound 1, binuclear subunits [Ag(1)2(bmte)2]2+ occur, which is connected by PMo12O40 3− (PMo12) anions to construct a one-dimensional (1D) chain. Furthermore, these chains are linked by Ag(2) ions acting as fuses to construct a two-dimensional (2D) gridlike sheet. Compound 2 shows trinuclear clusters, [CuI 3(bmte)3]3+, which are also connected by PMo12 anions to construct a 1D chain. These two neighboring chains arrange like a “zipper”. Compounds 3 and 4 are isostructural. In compound 3, the metal−organic subunit is a 2D sheet constructed by a series of three-membered circles. The polyoxoanions are sandwiched by these two sheets like a “hamburger”. The influence of the TM coordination nature on the assembly of multinuclear subunits in POM-based compounds is discussed.

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