New polymers of dithienyl-bipyridine metal complexes by anodic coupling of tris[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 ' -bipyridine]M(ClO4)(2) (M = Fe, Ru) has produced new ion-coordinating polyconjugated polymers. These polymers have been characterized by cyclic voltammetry, FTIR reflection-absorption spectroscopy, UV-vis spectroscopy, energy-dispersion X-ray analysis, electrochemical quartz crystal microscopy and in situ conductivity. The polymer films contain bis-coordinated bipyridyl complexes owing to ligand abstraction by protons produced in the coupling reaction. In situ conductivity versus potential is displayed at the oxidation redox potential as a redox-typical bell-shaped relationship with the maximum conductivities 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. Owing to this reason, the corresponding cobalt and nickel complexes cannot be polymerized at all. Films of the polymeric complexes perform a normally efficient electrocatalytic reduction of carbon dioxide. (C) 2001 Elsevier Science B.V. All rights reserved.