Unusual Cyan-Purple Electrochromism of Sandwich Phthalocyaninates Observed on the Example of µ-Carbido Diruthenium(IV) Complex

Current research in sandwich phthalocyaninates enjoys increasing interest due to peculiar properties of these compounds, i.e. their intense coloration and ability to change and control it via redox processes. Obviously, such effect found its application in development of electrochromic devices. In the case of commonly studied rare earth element bisphthalocyaninates, the most dominant electrochromic palette observed for them lies within the red-green-blue gamut. In this work, we report that an unusual sandwich – covalently-bridged μ-carbido diruthenium(IV) bisphthalocyaninate – exhibits equally unusual color changes upon its reversible electrochemical oxidation/reduction, namely switching from cyan to purple. The study provides a detailed spectroelectrochemical characterization of this μ-carbido-dimeric complex in solution, in thin cast and ultrathin Langmuir-Schaefer films, which all demonstrate aforementioned variable vibrant coloration in action.