Abstract: The proposed research will develop a comprehensive model of photophysical behavior of rhenium tricarbonyl-phenanthroline complexes on a level sufficient to enable their rational applications as photosensitizers of ultrafast electron and energy transfer, luminophores and molecular sensors. Quantum chemical (DFT-based) computational procedures for reliable characterization of electronic states of transition-metal complexes with redox-active ligands, description of their electron density distribution and prediction of spectral properties will be developed. Results will have a broader impact on our understanding of photophysics, photochemistry and redox-chemistry of coordination compounds.