SYNTHESIS AND ELECTROCHEMICAL PROPERTIES OF LY[3-(OMEGA-[4-(2,2'-BIPYRIDYL)]ALKYL)THIOPHENES], P(B(N)T), AND OF POLY[RU(II)(B(N)T)(3)(2+)]

The electropolymerization of a series of ligands 3-{omega-[4-(2,2'-bip yridyl)]alkyl)thiophene (B(n)T; n = 2, 5, 7, 9, 11) and their tris(lig and)ruthenium(II) complexes, [Ru{B(n)T}(3)](2+), is reported. The elec trochemical properties of the polymers were investigated using cyclic voltammetry, chronoamperometry and a.c. impedance spectroscopy. These studies reveal the dependence of the electrochemical behavior of the p oly[Ru{B(n)T}(2+)(3)] films upon the length of alkyl chains between th e thiophene and the bipyridyl groups, and on the supporting electrolyt es; longer alkyl chains induce more irreversible voltammetric behavior and larger charge transfer resistances in the cathodic processes of t he polymers. On the basis of these investigations, the mechanism of ch arge transfer in the polymer-modified electrodes has been evaluated, a nd interpreted. This shows that electrochemical processes of the polym ers in the anodic region are controlled both by kinetic and diffusion factors, whereas the primary influences in the cathodic region are ass ociated with kinetic factors arising from the alkyl chains.