Excitation energy transfer and photo-induced electron transfer in axial bispyrenyl phosphorus porphyrin derivatives:: factors governing the competition between energy and electron transfer processes under the existence of intramolecular π-π interaction

In order to investigate the competition between energy and electron transfer processes, pyrene-phosphorus(V)porphyrin triads in which two pyrenes are connected to a central phosphorus atom through various bridges were synthesized. The triads have pi-pi interaction between the pyrene and the porphyrin moieties. As a result, emissions from the photo-excited states of pyrene and porphyrin were quenched through energy and/or electron transfer processes. In the relaxation from the excited state pyrene, the predominant process changed according to solvents and donor-acceptor distances. (C) 1999 Elsevier Science S.A. All rights reserved.