Dinuclear Ru-Cu Complexes: Electronic Characterisation and Application to Dye-Sensitised Solar Cells

We prepared the complexes [Ru{4,4`-(CO2R-bpy)(2)}{Cu(exoO(2)-cyclam)}][NO3](2) [R = Et (1), H (2)], which possess a Cu-II centre covalently linked to a (bipyridyl)Ru-II fragment. The complexes were characterised by cyclic voltammetry, UV/Vis spectroscopy, hybrid DFT and TD-DFT (time-dependent density-functional theory) calculations, EPR (electron paramagnetic resonance), emission spectroscopy and UV/Vis spectroelectrochemistry, with the latter showing reversible conversion to the mono- and di-oxidised and mono- and di-reduced species. The data suggest the first oxidation to be largely based on the Ru centre but with little energetic difference between the highest occupied orbitals based on Ru and based on Cu. There was also evidence of solvent co-