Micellar Effect of Ammonium Based Cationic Surfactants on Kinetics of Methylene Blue-Assisted Ru (III) and Cu (II) Catalyzed Cysteine/Cystine Transformation in Acidic Aqueous Media

摘要

Kinetic investigations of cysteine-cystine transformation assisted by model electron acceptor methylene blue (MB) and catalyzed synergistically by Ru (III) and Cu (II) in aqueous media of varying pH, temperature and micellar solutions of two ammonium based cationic surfactants viz. octadecylammonium chloride (OAC) and octadecylpyridine-2-ylmethylammonium chloride (OPMAC) were carried out. The homogeneous electron transfer between cysteine and MB was observed to exhibit pH sensitive kinetics that is affected by the presence of ammonium based cationic surfactants. While the postmicellar concentrations of OAC decrease the rate of the cysteine oxidation, the presence of OPMAC micelles was observed to accelerate the said reaction. The observed micellar kinetic effects modeled through quantum mechanical calculations are explained in light of the reactant-micelle interactions. To the best of our knowledge the synthesis, micellization and micellar catalytic activity of OPMAC are yet to be reported in the literature.