Triplet porphyrins as donors in intramolecular electron transfer and theirintermolecular interaction with free radicals

Porphyrins and related compounds are basic moieties which upon photoexcitat ion produce paramagnetic transients important to many processes in biology, material science and light-energy conversion. This short review demonstrat es the application of time-resolved EPR spectroscopy to two processes in wh ich the pbotoexcited singlet and/or triplet are involved: (1) intramolecula r electron transfer in photoexcited donor-acceptor systems embedded in liqu id crystals, where the porphyrins an the electron donors attached to differ ent types of accepters; and (2) intermolecular magnetic interactions betwee n photoexcited porphyrin triplets and free radicals. In both systems the el ectron spin plays an important past with regards to the route of the magnet ic interactions involved. Copyright (C) 2001 John Wiley & Sons, Ltd.