Electropolymerization and characterization of an alternatively conjugated donor-acceptor metallopolymer: Poly-[Ru(4 '-(4-(Diphenylamino) phenyl)-2,2 ':6 ',2 ''-Terpyridine)(2)](2+)

A functionalized complex [Ru(L)(2)](PF6)(2) [L = 4'-[4-(diphenylamino)phenyl)]-2,2':6',2 ''-terpyridine] was synthesized and characterized by H-1 NMR, C-13 NMR and elemental analyses. Its oxidative electropolymerization was conducted by continuous cycling of the working electrode potential from 0 to 1.8 V in 0.1 mol L-1 Bu4NClO4/CH3CN solution containing 5.0 x 10(-4) mol L-1 monomer. The red hybrid polymer film, characterized by X-ray photoelectron spectroscopy (XPS), exhibited a non-diffusional charge transfer behaviour for Ru(III)/Ru(II) couple and an irreversible redox process of triphenylamine moiety on the Pt working electrode, as well as high stability in monomer-free electrolytic solution. The film thickness was easily tuned by controlling the number of potential sweeping cycle, and the AC impedance of as-formed film increased with cycling number. Morphological characterization of the film on indium tin oxide (ITO) was provided by scan electron microscopy (SEM) and atomic force microscopy (AFM). The donor-acceptor (D-A) polymer film on ITO showed a broad and red-shifted (MLCT)-M-1 wave in the UV-vis spectrum and a clearly electrochromic behaviour from red to black in the spectroelectrochemical study. (C) 2010 Elsevier B.V. All rights reserved.