Electrosynthesis and co-ordination chemistry of polymer films coated on electrode surfaces from pyrrole polypyridyls

Abstract

New functionalized polypyrrole films containing transition-metal complexes of the type [Mn(bipy)₃]²⁺(bipy = 2,2′-bipyridine) and [M^IL(diene)]⁺(M = Rh or Ir, L = 2,2′-bipyridine or 1,10-phenanthroline, diene = cycloocta-1,5-diene or norborna-2,5-diene) have been synthesized and characterized by electrochemical techniques and UV/VIS spectroscopy. The strategy is based on the complexation of Mn²⁺ cations and [{M^I(diene)Cl}₂] precursor complexes in polymer films, coated on platinum and carbon electrodes by oxidative electropolymerization of pyrrole-substituted 2,2′-bipyridine and 1,10-phenanthroline monomers in acidic MeCN electrolyte. The redox behaviour of poly[M^IL(diene)⁺] is strongly dependent on the size of the cation of the supporting electrolyte. This appears to be a consequence of its permeation through the film to maintain electroneutrality in the polymer.