Study of reactions of platinum complexes with chitosan.

摘要

The reactions of transition metal ions with various forms of chitosan, deacylated forms of chitin, have attracted much interest. However, previous work has failed to determine either the nature of the metal-chitosan complexes formed or their role in determining the macroscopic properties of the system. Of particular interest is the formation of gels through metal-chitosan bonding, at least in part. In this work, the reactions of platinum compounds, primarily {dollar}PtClsbsp{lcub}4{rcub}{lcub}2-{rcub},{dollar} with chitosan have been investigated through the solution and gel formation stages over a wide range of variables including the chitosan to Pt(II) concentration ratio, pH, chitosan concentration and chemical form (degree of deacylation of parent chitin), and molecular weight. The processes were measured by determining simultaneously the solution viscosity and the electronic spectra of the complexes formed. The kinetic results have been modelled by reference to known reactions and the model tested against the experimental spectra. The results show that the time of gelation depends on the formation of a critical number of trans platinum diamine complexes and varies systematically with hydrogen bonding and molecular weight of chitosan.