pH-dependent assembly of two inorganic-organic hybrid compounds based on octamolybdates: an unusual intercalated layer and a 3D 4-connected framework

Two novel inorganic-organic hybrid compounds based on octamolybdates, namely, [Cu(H2L)(2)(gamma-Mo8O26)]center dot(Mo6O19)center dot 2H(2)O (1) and [Cu(H2L)(gamma-Mo8O26)(H2O)(2)]center dot 5H(2)O (2), where L = 1,1'-(1,5-pentanediyl)bis[2-(4-pyridyl)benzimidazole], have been successfully synthesized at different pH values under hydrothermal conditions. Compound 1, which is hydrothermally prepared at pH approximate to 3.5, exhibits an entirely new type of intercalated layer. The nanosized hexamolybdate anions as guests are introduced into the layers. When the pH value is adjusted to 2, a structurally-different complex 2 was obtained. Compound 2 shows a unique 3D 4-connected framework constructed by inorganic layers and H2L2+ ligands as bridges. The two compounds were characterized by elemental analyses, IR spectra and TGA. Inaddition, the electrochemical properties of 1-modified carbon paste electrode (CPE) have also been investigated in 1 M H2SO4 aqueous solution.