Modelling the photosynthetic reaction centre: photoinduced electron transfer in a pyromellitimide-bridged ‘special pair’ porphyrin dimer

Abstract

Coproporphyrin-I has been bridged across one face by mesoporphyrin-II and across the other by a pyromellitimide, the resulting doubly-bridged compound showing rapid electron transfer between the ‘special pair’ porphyrin dimer and the pyromellitimide acceptor; both the excited singlet and charge-separated states have been observed in picosecond absorption and emission experiments, and a closely related side-by-side analogue lacks these ‘special pair’ properties, electron transfer being ca. 1000 times slower.