Synthesis of Rigid Porphyrin-Quinone Compounds for Studying Mutual Orientation Effects on Electron Transfer and Their Photophysical Properties

Article abstract of DOI:10.1246/bcsj.67.3067

A series of covalently linked porphyrin-quinone molecules in which a porphyrin ring is connected at two fixed distances with two different kinds of rigid spacers to benzoquinone were synthesized.The spacer is either spiro<4.4>nonane or trans-decalin.These compounds were designed to have a fixed orientation of different kinds with the same redox pair, the same separation distance, and the same number of intervening bonds.The forward electron-transfer rates were studied by fluorescence-lifetime measurements.Large differences in the rates were found in each pair, and the rates for those compounds having a spiro spacer were larger than those with a trans-decalin spacer.These differences were attributed to a difference in the molecular geometry of the spacer groups in each pair.