Electrochemical behavior and luminescent properties of a multilayer film containing mixed-addenda polyoxometalates K10H3[Eu(SiMo9W2O39)2] and tris(2,2'-bipyridine)ruthenium(II).

Inorganic-organic composite films containing the mixed-addenda heteropolytungsto-molybdate K(10)H(3)[Eu(SiMo(9)W(2)O(39))(2)]xH(2)O (abbreviated as EuSiMo(9)W(2)) and tris(2,2'-bipyridine)ruthenium(II) Ru(bpy)(2+)(3) (abbreviated as Ru(bpy)(3)) were fabricated by the layer-by-layer self-assembly method. UV-vis spectroscopy shows that the absorbance values at characteristic peaks increase linearly with the number of EuSiMo(9)W(2)/Ru(bpy)(3) bilayers, suggesting that the deposition process is linear and highly reproducible from layer to layer. The composition of the multilayer film was measured by X-ray photoelectron spectra. Atomic force microscopy presented a correspondingly uniform surface morphology and a homogeneity of the multilayer films. The film exhibited photoluminescence arising from the d-pi* metal-to-ligand transition of Ru(2+), and (5)D(0) metastable state to terminate levels in the (7)F(J) (J=0-4) ground-state multiplet transitions of Eu(3+). The film also exhibited catalytic activities toward the reduction of IO(-)(3), H(2)O(2), BrO(-)(3), NO(-)(2) and the oxidation of C(2)O(2-)(4). It may provide a novel material as bifunctional electrocatalysts and fluorescence probes in biochemistry, luminescence sensors, electroluminescent optical devices, and so on.