Grafting of imidazolium ion-terminated layer using electrochemical reduction of diazonium: Redox active counter anion exchange within the layer

Electrochemical reduction on carbon electrode of 1-nitrophenylethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid in acidic media containing sodium nitrite has been investigated. As a consequence, the corresponding diazonium was generated in situ in the vicinity of the electrode, then electroreduced onto the electrode surface inducing the attachment of phenyl imidazolium groups. The electrochemical behavior of the modified electrodes toward various redox probes was investigated. As a result, the attached layer acts as barrier against the electron transfer when using neutral and positively charged redox probes while, electron transfer transparency is obtained when using negatively charged redox species. The positively charged imidazolium attached onto the surface exhibits a selective electron transfer toward redox probe molecules. Finally, the capability to perform anion exchange within the immobilized layer was evaluated by incorporating a redox active counter anion.

► Electrochemical grafting from an ionic liquid. ► Nitrophenyl imidazolium layer attached onto carbon electrode. ► The positively charged layer exhibits a selective electron transfer. ► Anion exchange within the immobilized layer. ► Incorporating redox active counter anion.