Multi-colour electrochromic properties of Fe/Ru-based bimetallo-supramolecular polymers

A series of Fe/Ru-based bimetallo-supramolecular polymers were synthesized by a stepwise coordination of Fe(II) and Ru(II) ions to bis(terpyridyl)benzene (L1). The polymers exhibited multi-colour electrochromic behaviour based on the redox potential of the metal ion. Electrochemical and electrochromic properties of the polymer films were analyzed in acetonitrile with 0.1 M lithium perchlorate as an electrolyte. The polymer films showed high optical contrast and very fast response times, demonstrated by transmittance changes (Delta T) at 508 and 585 nm that were 68% and 37%, respectively, within a few seconds. Coloration efficiencies (eta) were established for the first time in a metallo-supramolecular electrochromic system, with values of 242.1 and 188.2 (cm(2) C-1) at different wavelengths.