Effects of micelles on the complex formation of [PtCl(dien)](+) with biologically relevant ligands

Abstract

Substitution reactions of [PtCl(dien)](+) (dien = diethylenetriamine) with some biologically relevant ligands, such as L-methionine ((L)-Met), glutathione (GSH), and guanosine 5-nionophosphate (5-GMP), were studied in aqueous 0.10, 0.05, and 0.01 M NaClO4 Solutions at pH 2.5 using UV-vis spectrophotometry. The kinetics and mechanism of the complex-formation reactions were Studied as I function of nucleophile concentration and temperature. These reactions were also Studied in the presence and absence of micelles of sodium dodecyl sulfate (SIDS). The presence of anionic micelles accelerated complex-forination. The largest effect of micelles has been observed in the case of L-methionine. On the other hand, all increase in the ionic strength in the presence of micelles caused a decrease in the rate. The negative entropies of activation support all associative complex-formation mechanism.