RESUMO
A global and extremely simple strategy to prepare a covalently attached monolayered organic film on a carbon surface is presented. The approach is centered on the strict control of the radical polymerization traditionally observed when aryldiazonium salts are reduced. By exploiting the reductive properties of superoxide ions generated from atmospheric dioxygen at the grafting potential, the diazonium concentration is drastically lowered at the substrate/solution interface, resulting in the formation of ultrathin films. As the presented approach does not require any specific synthesis or any redox mediator addition, and is only diffusion controlled by the dissolved dioxygen, it is suitable for the preparation of a large range of functional surfaces on the nanometric scale.
RESUMO
Postfunctionalization of glassy carbon electrodes previously modified by reduction of 4-azidobenzenediazonium was exploited to conveniently synthesize controlled mixed organic layers. Huisgen 1,3-dipolar cycloaddition was used to anchor functional entities to azide platform. By this way, ((4-ethynylphenyl)carbamoyl)ferrocene (Ï-Fc) was coimmobilized with a set of acetylene derivatives: 1-ethynyl-4-nitrobenzene (Ï-NO2), 4-ethynylaniline (Ï-NH2) or ethylnylbenzene (Ï). The composition of the resulting organic layers was tuned by adjusting the acetylene derivatives ratio in the postfunctionalization binary solution. Electronic properties of the substituents beared by the aromatic rings were found to have a strong impact on the cycloaddition kinetics toward the confined azide moieties. From this study, rules to prepare finely tuned bifunctional organic layers can be anticipated.
