Electron Transport in Ru and Os Polybenzimidazole-Based Metallopolymers

Abstract

A series of conjugated polymer−redox polymer hybrids based on the complexation of poly-(bibenzimidazoles) with bis-(2,2'-bipyridyl)Ru^(2+) and bis-(2,2'-bipyridyl)Os^(2+) has been prepared to investigate the effects of electronic communication between metal centers through the conjugated backbone. Electron transport rates in the mixed valence M(III/II) states have been measured as electron diffusion coefficients (D_e) by impedance spectroscopy and dual (sandwich) electrode voltammetry. D_e values are generally higher than for nonconjugated Ru(2,2'-bipyridyl)^3^(3+/2+)-type polymers, and their dependencies on the metal (Os or Ru), pH and nature of the polymer backbone are consistent with significant contributions from superexchange mechanisms. Hole-type superexchange appears to dominate in the Ru polymers, while a number of observations indicate that electron-type superexchange may dominate for the Os complexes.

Additional details