Intramolecular photoinduced charge separation and charge recombination of the product ion pair states of a series of fixed-distance dyads of porphyrins and quinones: energy gap and temperature dependences of the rate constants

Abstract

Intramolecular photoinduced charge separation (CS) and charge recombination (CR) of the product ion pair (IP) state of a series of fixed-distance dyads consisting of free-base porphyrin or zinc porphyrin and quinones have been investigated by means of picosccond-femtosecond laser spectroscopies in order to examine the energy gap and temperature dependences of CS and CR reactions in nonpolar media. Obtained CS rates were in the normal region, up to the neighborhood of the top region, and CR rates were in the inverted region; their energy gap dependences at room temperature were approximately reproduced by a semiclassical formula taking into consideration the high-frequency quantum mode of nuclear vibrations, although the CS rates near the top region did not show indication of the shift to the inverted region, contrary to the calculation