Redox behavior of a ferrocene monolayer on SiO2 obtained after click-coupling

Abstract

Redox active ferrocene derivatives were grafted upon SiO2 surface via a carbon-based linker. The indirect grafting procedure consisted in a silanization followed by a click-chemistry reaction. This immobilization method of ethynyl-ferrocene yields a mixed organic/inorganic charge transfer modulation medium made of a C3 linker ended by a 1,2,3-triazole, bound to a thin SiO2 layer. Such a linker has never been tested before. Its use combines the advantages of a thin dielectric layer (SiO2+>C3 linker) to the versatility of a two-step process that could easily be transferred to other sensitive or hard to synthesize compounds. Such organic/inorganic linker has been tested to tune the redox properties and charge transfer kinetics of the overall hybrid system and the results could be of importance for hybrid memory devices applications. Cyclic voltammetry studies conducted on this hybrid system were indeed used to confirm ferrocene immobilization, determine the molecular surface coverage and study the redox charge/discharge kinetics. The obtained results show the good surface coverage and charge retention properties, achieved by grafting upon SiO2 via a >C3 linker. For comparison, the ferrocene compound was also immobilized on Si (C2 linker).