Reductive electropolymerization of complexes containing an aldehyde-substituted derivative of 2,2′-bipyridine

Abstract

Polypyridyl complexes of Fe II and Zn II containing the ligand 4-methyl-2,2′-bipyridyl-4′-carboxaldehyde(4-CH 3-4′-CHO-bpy) have been prepared. Upon electrochemical reduction of these complexes coupling reactions occur at the ligands, yielding thin metal-complex-containing polymeric films on the electrode surfaces. The polypyridyl ligands that form in a polymerized film of [Zn(4-CH 3-4′-CHO-bpy) 3] 2+ have been isolated following chemical degradation and characterized using fast atom bombardment mass spectrometry and 1H nuclear magnetic resonance. These and other results are consistent with a mechanism for polymerization that involves radical—radical coupling at the aldehyde substituents following reduction. The coupling occurs with the formation of a 1,2-diol linkage between the bipyridine ligands which creates a basis for network polymerization.