A generic monolayer platform for the functionalization of surfaces through Sonogashira coupling

Different modified glassy carbon electrodes prepared by electroreduction of diazonium salts were post-functionalized by Sonogashira cross-coupling reactions with ferrocenyl moieties to elucidate how the packing of ferrocene redox centers are impacted by the structure of the chemically addressable underlying layers. Herein, the reactivity of iodophenyl and ethynylphenyl-terminated carbon electrodes towards the Sonogashira coupling with ethynylferrocene and iodoferrocene was examined and multilayer and monolayer underlying chemically addressable platforms were compared. For the ethynylphenyl-terminated carbon electrode, comparison between click chemistry and Sonogashira coupling was performed. The modified electrodes were examined by X-ray photoelectron spectroscopy (XPS) analysis and atomic force microscopy (AFM) experiments were achieved to ascertain if multi or monolayers were obtained. After post-functionalization with the redox-active subunits, the modified electrodes were examined by cyclic voltammetry. A novel strategy to prepare an iodophenyl monolayer reactive platform suitable for post-functionalization by Sonogashira reaction is presented, providing a way to attach a molecule on surface in a fully conjugated fashion.