Computational study of the lowest triplet state of ruthenium polypyridyl complexes used in artificial photosynthesis

The potential energy surfaces of the first excited triplet state of some ruthenium polypyridyl complexes were investigated by means of density functional theory. Focus was placed on the interaction between the geometrical changes accompanying the photoactivity of these complexes when used as antenna complexes in artificial photosynthesis and dye-sensitized solar cells and the accompanying changes in electronic structure. The loss process (MLCT)-M-3 -> (MC)-M-3 can be understood by means of ligand-field splitting, traced down to the coordination of the central ruthenium atom.