New polymers of dithienyl-bipyridine metal complexes by anodic coupling oftris[5,5 '-bis(3,4-(ethylenedioxy)thien-2-yl)-2,2 '-bipyridine]M(ClO4)(2) (M = Fe, Ru) - A complex polymerization mechanism

Anodic coupling of tris[5,5 ' -bis(3,4-(ethylenedioxy)thien-2-yl)-2,2 ' -bi pyridine]M(ClO4)(2) (M = Fe, Ru) has produced new ion-coordinating polyconj ugated polymers. These polymers have been characterized by cyclic voltammet ry, FTIR reflection-absorption spectroscopy, UV-vis spectroscopy, energy-di spersion X-ray analysis, electrochemical quartz crystal microscopy and in s itu conductivity. The polymer films contain bis-coordinated bipyridyl compl exes owing to ligand abstraction by protons produced in the coupling reacti on. In situ conductivity versus potential is displayed at the oxidation red ox potential as a redox-typical bell-shaped relationship with the maximum c onductivities around 10(-4) S cm(-1). The electrodeposition of thick films is made possible by the proximity of the deposition voltage and the polymer redox potential, which makes the deposited material redox conductive. Owin g to this reason, the corresponding cobalt and nickel complexes cannot be p olymerized at all. Films of the polymeric complexes perform a normally effi cient electrocatalytic reduction of carbon dioxide. (C) 2001 Elsevier Scien ce B.V. All rights reserved.