Kinetic studies and mechanism of hydrogen peroxide catalytic decomposition by cu(II) Complexes with polyelectrolytes derived from l-alanine and glycylglycine

Abstract

The catalytic decomposition of hydrogen peroxide by Cu(II) complexes with polymers bearing L-alanine (PAla) and glycylglycine (PGlygly) in their side chain was studied in alkaline aqueous media. The reactions were of pseudo-first order with respect to [ H2 O2 ] and [L-Cu(II)] (L stands for PAla or PGlygly) and the reaction rate was increased with pH increase. The energies of activation for the reactions were determined at pH 8.8, in a temperature range of 293-308K. A suitable mechanism is proposed to account for the kinetic data, which involves the Cu(II)/Cu(I) redox pair, as has been demonstrated by ESR spectroscopy. The trend in catalytic efficiency is in the order PGlygly > PAla, due to differences in modes of complexation and in the conformation of the macromolecular ligands. Copyright © 2010 Spyridon Skounas et al.