Tuning dimensionality of octamolybdate structures through selecting different ligands

By using different organic ligands, six octamolybdate hybrid compounds with different dimensionalities, namely, [Ag4 (dpz)8 (β-Mo8O26)] (1), [Cu4(dpz)8 (β-Mo8O26)] (2), [Co2(tbz)4(H2O)2 (β-Mo8O26)] (3), [Ni2(tbz)4(H2O)2 (β-Mo8O26)]·2H2O (4), [Cu(tbz) (H2O) (β-Mo8O26)1/2] (5), [Cu(btp)2(H2O) (β-Mo8O26)1/2]·2H2O (6) (dpz = 3,5-dimethyl-pyrazolidine, tbz = 2-(4-thiazolyl)benzimidazole, btp = 1,3-bis(1,2,4-triazol-1-yl)propane), have been synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction analyses, elemental analyses and IR spectra. By using a dpz ligand, two isostructural 0D compounds 1 and 2 were obtained, with four {M(dpz)2} fragments (M = Ag for 1, Cu for 2) supporting one anion. When rigid tbz was used, 0D compounds 3 and 4, and 1D structure of compound 5 was constructed. The tbz play a terminate chelate role in these compounds. By selecting a flexible bis(triazole) btp ligand with more N donors, a 2D hamburger-like layer is formed. Adjacent layers further interpenetrate with each other to construct a 3D interpenetrating framework of compound 6, realizing dimensionality from 2D to 3D. Using different ligands to tune the dimensionality of POM-based structures is rational. The electrochemical and photocatalytic properties of compounds 1–6 were researched, in which the POM subunit is regarded as active component but not organic moiety.