The effect of polymer chain structure on the catalytic activity of polymer-copper complexes

Abstract

Polymer chain effects on catalytic activity were investigated for binuclear coordination complexes of copper ions with polymeric tertiary amines like dimethylaminomethylated polystyrene, copolymers of styrene with 4-vinylpyridine or N-vinylimidazole, and some N-alkylated polyimines. Oxidative coupling of phenols by oxygen in the presence of these copper complexes was chosen as a model reaction. Two polymer effects will be discussed: (i) the increase of catalytic activity with increasing degree of loading of the polymer chains with catalytic centers. This effect will be analyzed in terms of changes in activation parameters and can be related to an increase in conformational freedom of the intermediate chain segments during deformation of the catalyst-substrate complex prior to electron transfer from substrate to copper ions; (ii) restrictions in the above enhancement of catalytic activity at still higher degrees of loading because the intermediate chain segments become too short for linking neighbouring ligands to the same complex.