Synthesis and structural characterization of polyoxometalates incorporating with anilinium cations and facile preparation of hybrid film

The self-assembly reaction of tungstate and copper(II) in the presence of aniline (ANI) and phosphoric acid led to the formation of an anilinium (ANIH+) salt of mono-substituted Keggin-type polyoxotungstophosphate (ANIH)5[PCu(H2O)W11O39](ANI)·8H2O (1), while the reaction of heptamolybdate in the coexistence of copper(II), phosphoric acid and ANI yielded an ANIH+ salt of Strandberg-type pentamolybdodiphosphate, (ANIH)2[(PO4)2Mo5O15{Cu(ANI)2(H2O)}2](ANI)·2H2O (2). These compounds were characterized by elemental analysis, infrared spectroscopy and X-ray single-crystal analysis. The compound 1, crystallizing in trigonal, P 3 ¯ , a = 13.883(4), c = 10.187(3) Å, Z = 1, consists of copper mono-substituted Keggin-typed [PCu(H2O)W11O39]5− anion surrounded by six ANI molecules, of which five are protonated (ANIH+). The compound 2, crystallizing in triclinic, P 1 ¯ , a = 13.98(2), b = 14.73(1), c = 16.24(1) Å, α = 111.27(3), β = 97.42(3), γ = 99.54(4)°, Z = 2, consists of Strandberg-type pentamolybdodiphospate [(PO4)2Mo5O15]6− anions interconnected by two Cu(ANI)2(H2O) linkers to form a 1D-chain structure. A potentiostatic electrolysis of 1 in aqueous solution gave rise to electropolymerization of the ANIH+ cations (and ANI) and deposition with the [PCu(H2O)W11O39]5− anion on an ITO electrode, forming a nano-structured polyaniline/[PCu(H2O)W11O39]5− hybrid thin film.