This work describes a simple method to attach TEMPO by an amide link to a graphite felt electrode. The derivatization of the electrode is highlighted by cyclic voltammetry and XPS analyses. Cyclic voltammetry analyses showed the catalytic activity of the grafted TEMPO in both organic and aqueous media. The electrolyses revealed improved stability of the grafted catalyst in aqueous medium compared to acetonitrile. Furthermore, the catalyst is more stable when it is immobilized onto the electrode than when it is in homogeneous solution. The XPS analyses of the grafted felt after electrocatalysis in aqueous medium shows that the degradation of the modified electrode during the electrolysis is not due to a break of the amide link between the graphite felt and TEMPO.

Asymmetrical N-tripodal ligands have been synthesized in three steps. Diversity has been introduced at the first step of the synthesis by adding pyrazine, pyridine, benzyl and thiophene rings. The corresponding Cu^II complexes have been prepared by reaction with CuCl₂ and characterized by Electron Paramagnetic Resonance (EPR), UV-Vis spectroscopies and cyclic voltammetry. The data show that the ligand coordinates to Cu^II in a mononuclear fashion in solution and that the complexes display a square pyramidal geometry. All complexes are characterized by a quasi-reversible one-electron redox behavior in acetonitrile. The ability of the complexes to oxidize 3,5-di-tert-butylcatechol to 3,5-di-tert-butylquinone has been studied and the results show that the rate of the reaction depends on the basicity and the steric hindrance of the heterocyclic donor. Best results have been obtained with Cu^II complexes coordinated to bidentate ligands, since they facilitate the approach and the coordination of catechol to the metal. Particularly, the introduction of a thiophenyl group to mimic the sulfur atom at proximity to the catalytic center in the catechol oxidase protein structure improves the catalytic activity of the complex.