Photoinduced electron transfer dynamics for self-assembled porphyrin arrays in solutions and films

Electronic excitation energy deactivation in self-assembled porphyrin triad s has been studied by the time correlated single photon counting technique as a function of the solvent polarity (toluene-acetone mixtures), temperatu re (77-350 K), and mutual spatial arrangement of the donor and acceptor sub units. The donor (Zn-octaethylporphyrin chemical dimer) fluorescence quench ing with time constant of 1.7+10 ps is due to competing energy migration an d electron transfer processes to the acceptor (dipyridyl substituted tetrap yrrole extra-ligand). The quenching of the acceptor fluorescence (by simila r to1.3-1.6 times) does not significantly depend on the mutual spatial arra ngement of the triad subunits and increases with the solvent polarity risin g and the decrease of the: temperature. The obtained experimental data are analyzed using the reduced density matrix formalism in the Frame of Haken-S trobl-Reineker approach taking into account the energy transfer charge sepa ration, and the dephasing of coherence between the excited electronic state s of the triad.