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A series of Zn(II) porphyrins which have asymmetrically substituted mesogroups have been studied with UV–vis, resonance Raman, emission spectroscopies, and density functional theory (DFT) calculations. Dye-sensitized solar cells (DSSCs) of these materials have also been fabricated and their performance parameters measured. DFT calculations show perturbation of frontier molecular orbitals, and redox-active substituents cause greater perturbation than nonredox active substituents. All substituents cause a broadening of the Bband, as is common for substituted porphyrins. TD-DFT calculations and resonance Raman spectroscopy suggest the donor and acceptor substituents play a small role in transitions of the Bband. The mesodonor substituent is electronically isolated and does not significantly perturb the molecular orbitals (MOs), while the mesocyanoacrylic acid TiO2binding group has a much larger effect on the egMO in particular. However, in the oxidized porphyrin species, the hole is located on the mesosubstituent, localizing it away from the semiconductor surface, which should reduce recombination and also improve performance. They show modest efficiency when incorporated into solar cells; however, the pattern of behavior is consistent with localization of charge at the mesounit.

A recently reported new class of ruthenium complexes containing 2,2′‐bipyridine and a dipyrrin ligand in the coordination sphere exhibit both strong metal‐to‐ligand charge‐transfer (MLCT) and π–π* transitions. Quantitative analysis of the resonance Raman scattering intensities and absorption spectra reveals only weak electronic interactions between these states despite direct coordination of the bipyridyl and dipyrrin ligands to the central ruthenium atom. On the basis of DFT calculations and time‐dependent DFT (TD‐DFT), we propose that the electronic excited states closely resemble “pure” MLCT and π–π* states. Resonance Raman intensity analysis demonstrates that a large amplitude transannular torsional motion provides a mechanism for relaxation on the π–π* excited‐state surface. We assert that this result is generally applicable to a range of dipyrrin complexes such as boron–dipyrrin and metallodipyrrin systems. Despite the large torsional distortion between the phenyl ring and the dipyrromethene plane, π–π* excitation extends out onto the phenyl ring which may have important consequences in solar‐energy‐conversion applications of ruthenium–dipyrrin complexes.