Photoinduced Electron Transfer of Porphyrin Isomers: Impact of Molecular Structures on Electron-Transfer Dynamics

Porphyrins have been investigated for a long time in various fields of chemistry owing to their excellent redox and optical properties. Structural isomers of porphyrins have been synthesized, namely, porphycene, hemiporphycene, and corrphycene. Although the number of studies on these structural isomers is limited, they exhibit interesting properties suitable for various applications such as photovoltaic devices, photocatalysts, and photodynamic therapy. In the present review, we summarized their photoinduced electron-transfer processes, which are key steps of various photofunctions. Their electrochemical and photophysical properties are summarized as basic properties for the electron transfer. Furthermore, differences among these isomers in the electron-transfer processes are clarified, and its origin has been discussed on the basis of their molecular structures.