Synthesis, structure and properties of an organic–inorganic hybrid independent 1-D double-chain Keggin-type silicotungstate with mixed ligands

Abstract

A novel organic–inorganic hybrid independent 1-D double-chain silicotungstate [Cu(biim)2][Cu(4,4′-bpy)(biim) (H2O)][α-SiW12O40]·3H2O (1, biim=2,2′-biimidazole, 4,4′-bpy=4,4′-dipyridine) has been successfully synthesized by reaction of Na10[A-α-SiW9O34]·18H2O, CuCl2·2H2O, EuCl3, biim and 4,4′-bpy under 160°C hydrothermal environment and characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction. The most remarkable structural feature of 1 is that two types of independent 1-D chains are paralleling and one is constructed from plenary Keggin [α-SiW12O40]4− units and [Cu(biim)2]2+ linkers while the other is based on [Cu(biim)(H2O)]2+ cations and 4,4′-bpy connectors. The variable-temperature magnetic susceptibility of 1 shows the weak antiferromagnetic exchange interactions within CuII centers. Furthermore, the solid-state electrochemical properties of 1 have been also measured in 0.5mol·L−1 Na2SO4+H2SO4 aqueous solution by entrapping it in a carbon paste electrode.