Factorial design analysis of the catalytic activity of di-imine copper(II)complexes in the decomposition of hydrogen peroxide

Factorial design analysis was applied to the study of the catalytic activit y of diimine copper(II) complexes, in the decomposition of hydrogen peroxid e. The studied complexes show a tridentate imine ligand (apip), derived fro m 2-acetylpyridine and 2-(2-aminoethyl)pyridine, and a hydroxo or an imidaz ole group at the fourth coordination site of the copper ion. The factorial design models for both [Cu(apip)imH](2+) and [Cu(apip)OH](+) were similar. increasing the peroxide concentration from 3.2 x 10(-3) to 8.1 x 10(-3) mol L-1 resulted in increased oxygen formation. Increasing the pH from 7 to I I also increased oxygen formation and had an effect about twice as large as the peroxide one. Both complexes also had an important interaction effect between peroxide concentration and pH. However, increasing the catalyst con centration led to a decrease in total oxygen formation. The obtained result s were corroborated by further data, achieved by using the usual univariate method, and helped to elucidate equilibrium steps occurring in the studied systems. in very alkaline solutions, the studied [Cu(apip)imH](2+) complex can form the corresponding dinuclear species, [Cu-2(apip)(2)im](3+). While the mononuclear complex proved to be an efficient catalyst in hydrogen per oxide decomposition, the corresponding dinuclear compound seemed to be able to coordinate with the dioxygen molecule, inhibiting its observed release. (C) 2001 John Wiley & Sons. Inc.