FEMTOSECOND DYNAMICS OF METALLOPORPHYRINS - ELECTRON-TRANSFER AND ENERGY REDISTRIBUTION

Femtosecond-resolved, real-time dynamics of the low-lying excited stat e (2)Q( pi,pi ) of cobalt(II) tetraphenylporphyrin are reported in di fferent solvents of varying polarity and structure. The dependence of the dynamics on the probing wavelength and on the metal and porphyrin substitution was also investigated. The decay in the pi system of the porphyrin occurs with a lifetime of 220 fs in benzene, while a second process with a lifetime of 1.8 ps is consistent with a proposed model for intramolecular charge separation: porphyrin a(2u)(pi)--> Co(d(z)2) . The dynamics of the charge transfer state is influenced by the solve nts' polarity and coordination ability. (C) 1998 Elsevier Science B.V. All rights reserved.