Electrochemistry and Reactivity of Surface-Confined Catechol Groups Derived from Diazonium Reduction. Bias-Assisted Michael Addition at the Solid/Liquid Interface

We have designed a novel catechol-modified electrode that could be used for bias-assisted Michael addition at the solid/liquid interface. The glassy carbon electrode was modified by the electrochemical reduction of a catechol para-substituted phenyldiazonium salt. The electrochemistry of surface-confined catechol moieties was investigated by cyclic voltammetry. The transfer coefficient and apparent surface standard electron-transfer rate constant were obtained using Laviron's theory. We demonstrate that o-quinone moieties linked to the surface remain quite reactive with nucleophilic species by Michael addition at the solid/liquid interface. To demonstrate the versatility of this procedure, 4-nitrobenzyl alcohol, (4-nitrobenzyl)amine, and a ferrocenealkylamine were chosen as nucleophile models due to their well-known redox properties. Electrochemically triggered Michael addition was validated, leading to redox headgroup-tethered surfaces.