Electrochromic Behaviour of Polynuclear Ruthenium Complexes on Nanocrystalline SnO2

Abstract

The trinuclear [{Ru(NH3)4(py-COOH)}(μ-CN){Ru(bpy)2}(μ-CN){Ru(NH3)4(py-COOH)}]6+ (py-COOH = isonicotinic acid, bpy = 2,2'-bipyridine) (1) and dinuclear [{Ru(dcb)2}2L]7- (dcb = 2,2'-bipyridine-4,4'-dicarboxylic acid, H3L = 9-phenyl-2,3,7-trihydroxy-6-fluorone) (2) complexes were prepared and their spectroelectrochemical behaviour characterised in solution and on conductive glass electrodes layered with Sb-doped nanocrystalline SnO2. The systems display a reversible redox response in a narrow potential range (-0.5 to +0.5 V vs SCE) and offer the possibility of controlling colour changes of electrochromic devices through variations of the coordinated and bridging ligands at the metal centres. SnO2(Sb) electrodes loaded with these dyes show switching times of the order of ms.