Photochemistry of aromatic ketones in sodium dodecyl sulphate micelles in the presence of unsaturated fatty acids

Abstract

Laser-flash photolysis has been employed to characterize the behaviour of the free radicals created in the photochemical reaction of benzophenone (BZP), as well as of its lipoidal derivative, benzophenone-4-heptyl-4?-pentanoic acid (BHPA), with chosen unsaturated fatty acids in sodium dodecyl sulphate micelles. The calculated rate constants were used to study the "cage effect" i.e., the recombination of the created radical-pairs (BZP, BHPA ketyl radical - lipid radical) inside the highly limited space of the SDS micelles. The "cage effect" appears to be the dominant event inside SDS micelles, dependent on the structure of both the reactants-precursors. The fractions of the initially created radical-pairs which escape the "cage effect" and exit into the surrounding aqueous phase do not exceed 16 %. This fact is of enormous importance for the self-control of the pathogenic process of lipid peroxidation.