FLASH PHOTOLYTIC INVESTIGATIONS OF THE ELECTRON TRANSFER BETWEEN AROMATIC HYDROCARBON RADICALS AND TRYPTOPHAN IN MICELLAR SOLUTIONS

Abstract— Electron transfer reactions between tryptophan and cation radicals of various polycyclic hydrocarbons which are known to differ with respect to their carcinogenic and photodynamic activity have been investigated by flash spectroscopy. The hydrocarbons were solubilized in sodium dodecyl sulfate micelles. Their cation radicals were produced by photoionization probably via the excited singlet states. In the case of benz[a]anthracene, benzo[ghi]perylene, pyrene, benzo[rst]pentaphene, dibenz[a, h]-anthracene and anthracene, the electron transfer takes place in the Stern layer of the micelles and leads to neutral tryptophan radicals. It is assumed that tryptophan forms charge transfer complexes with the cation radicals of 3-methylcholanthrene and 7,12-dimethylbenz[a]anthracene. With perylene tryptophan only reduces the radical yield. New species could not be detected in this case. No correlation exists between the carcinogenic or the photodynamic activity of the hydrocarbons and the electron transfer behaviour of their cation radicals.