Facile immobilization of pyridine at gold, silver, and carbon surfaces. Generation of multi-strata versatile electrodes

•A general method for immobilizing pyridines at gold, glassy carbon, and silver is proposed•High levels of grafting are obtained•Multi-strata alkyl pyridinium deposits are obtained (reaction of primary grafted pyridine with 1-iodoalkylpyridines)•A simple reduction of the multi-strata composites resets the system to pyridine mono-layers•Reactivity of grafted pyridine towards functional 1-iodoalkanes permits versatile and reversible modifications of the primary pyridine layer

Electrochemical reduction of 4-(ω-haloalkyl)pyridines (Py-(CH2)n-X, X = I, Br, and Cl) in organic polar solvents leads to the efficient immobilization of pyridine at various solid electrodes (in particular at gold and different carbons). It is expected that the primarily immobilized pyridine layer (first stratum) is reactive towards the haloalkyl substrate in solution to afford – especially with iodides – multi-pyridinium layers readily electroactive in the course of electrolyses. Similar behaviour, though much slower, was observed for Py-(CH2)n-Br. These experimental evidences were applied to build different combined layers (e.g., reacting primary pyridine deposits – by simple dipping in the corresponding solution – with different electrophilic reagents like 1-iodoalkanes eventually labelled with ferrocene). This new modification process, supposedly extendable to many N-aromatic systems, appears as a new mode of making functional multilayer or redox-active onium-type electrodes by cathodic activation of carbon-halogen bond scission.

Graphical abstractA general mode of immobilization of alkyl pyridines at gold, silver and carbon.Figure optionsDownload full-size imageDownload as PowerPoint slide