Multidimensional all-inorganic frameworks based on new molybdovanadate cluster of [VMo7O28]9- with Cu(II) linker showing semiconducting behavior

Three multi-copper molybdovanadate cluster compounds [Cu-8(OH)(2)(H2O)(2)V10Mo30O132](20-) (1), {[CuNa(H2O)(6)][Cu(H2O)(4)](2)[Cu-8(OH)(2)(H2O)(2)V9Mo30O128]}(10-) (2), {[Cu0.5Na0.5(H2O)(3)][Cu(H2O)(4)](2) [Cu-6(OH)(2)(H2O)(2)V9Mo23O108]}(9.5-) (3), containing a novel [VMo7O28](9-) fragment, have been isolated by using a one-pot self-assembly method. These three compounds were characterized by elemental analysis, single-crystal X-ray diffraction, IR spectroscopy, UV-vis spectroscopy, cyclic voltammetry, magnetic properties analysis, and thermal gravimetric analysis. The Z-shaped [Cu-8(OH)(2)(H2O)(2)V9Mo30O128](17-) anions of compound 2 can transform into the banana-shaped {Cu-6(OH)(2)(H2O)(2)V9Mo23O108} units of compound 3 by only changing the pH from 4.5 to 5.0, while the introduction of nitrilotriacetic acid as an assistant ligand ensures the formation of the zero-dimensional compound 1. Magnetic studies indicate the presence of strong antiferromagnetic interactions in compounds 1-3, and the three compounds also exhibit obvious electrocatalytic activities for nitrate reduction. The semiconducting properties of these solid state compounds were revealed from the measurements of the diffuse reflectance UV-vis spectra, in which the band gap values at ca. 2.5 eV are similar to inorganic semiconductor materials, suggesting potential applications in areas of photocatalysis and light-to-electricity conversion.