Synthesis and photophysical studies of porphyrin-ferrocene conjugates

The porphyrin-ferrocene conjugates ( P-nFc; n = 1, 2 and 4 ), which are simple examples of a donor-acceptor charge separation system, were synthesized. Their photoindued intramolecular and intermolecular processes have been investigated by time-resolved emission and nanosecond transient absorption techniques. Upon excitation of the porphyrins ( H 2 P and ZnP ) moieties, an efficient fluorescence quenching of the excited singlet porphyrin is observed. It was found that the quenching efficiency increases with increasing number of attached ferrocene moieties and solvent polarity. The main quenching pathway involves (i) electron transfer from ferrocene to the singlet excited porphyrin and (ii) the heavy-atom effect.