Electrochemical formation of nickel macrocyclic complex-based films: Application to the electrocatalysis of the oxidation of phenol derivatives.

The electrochemical formation of film-based macrocyclic planar nickel compl exes (porphyrins and phthalocyanines) in alkaline aqueous solution is descr ibed. The complex-based modified electrodes were characterized by cyclic vo ltamperometry and spectrophotometry. The results show that all the electrof ormed films, prepared in NaOH 0.1 M or in organic media and then treated in NaOH 0.1 M solution, exhibited the same electrochemical behavior which is similar to that shown by nickel hydroxide modified electrode in alkaline so lution. Anyhow, the spectrophotometric characterization of these films conf irmed that the structure of the planar complex configuration remained uncha nged. A mechanism for the formation of the nickel complex-based films is su ggested. In addition, the electrocatalytic properties of the modified elect rodes have been studied with p-chlorophenol and p-nitrophenol at neutral pH .