A generic platform for the addressable functionalisation of electrode surfaces through self-induced "electroclick"

A novel and general strategy for the immobilisation of functional objects onto electrodes is described. The concept is based on the addition of two pendant ethynyl groups onto a bis(pyridyl)amine derivative, which acts as a molecular platform. This platform is pre-functionalised with an N(3)-tagged object of interest by Huisgen cycloaddition to one of the ethynyl groups in biphasic conditions. Hence, when complexed by Cu(II) , this molecular-object holder can be immobilised, by a "self-induced electroclick", through the second ethynyl group onto N(3)-alkanethiol self-assembled monolayers on a gold electrode. Two different functional groups, a redox innocent ((CH(2))(3)-Ph) and an electrochemical probe (ferrocene), were immobilised by following this strategy. The in situ electrochemical grafting showed, for both systems, that the kinetics of immobilisation is fast. The voltammetric characterisation of the surface-tagged functionalised copper complexes indicated that a good surface coverage was achieved and that a moderately fast electron-transfer reaction occurs. Remarkably, in the case of the redox-active ferrocenyl-immobilised system, the electrochemical response highlighted the involvement of the copper ion of the platform in the kinetics of the electron transfer to the ferrocene moiety. This platform is a promising candidate for applications in surface addressing in areas as diverse as biology and materials.