Electrochemistry and spectroscopy of substituted [Ru(phen)3]2+ and [Ru(bpy)3]2+ complexes

Abstract The metal-to-ligand charge transfer property of nitrogen-based ruthenium complexes earns it a central place in dye-sensitized solar cell and photo-catalytic H2O and CO2 reduction research and applications. Electronic and spectral tuning are conveniently done by altering substituents and ligands. Cyclic voltammograms and UV–visible spectra of a synthesized series of electronically altered phenanthroline and bipyridyl ruthenium complexes (ΔE°' > 1.4 V for RuII-III) were obtained and, amongst others, correlated with DFT computed HOMO energies and ionization potentials. A good linear relationship with R2 = 0.97 were found for the combined bipyridyl and phenanthrolinato ruthenium series, thereby providing a convenient computational tool for the theoretical prediction of associated redox potentials. TDDFT closely simulates spectral properties of these complexes, where λmax varies from 420 to 520 nm. The former wavelength is representative of the dione-phenanthroline and the latter of the dinitro-bipyridyl ruthenium complex.