Efficient Covalent Modification of a Carbon Surface: Use of a Silyl Protecting Group To Form an Active Monolayer

A global strategy to prepare a versatile and robust reactive platform for immobilizing molecules on carbon substrates with controlled morphology and high selectivity is presented. The procedure is based on the electroreduction of a selected triisopropylsilyl (TIPS)-protected ethynyl aryldiazonium salt. It avoids the formation of multilayers and efficiently protects the functional group during the electrografting step. After TIPS deprotection, a dense reactive ethynyl aryl monolayer is obtained which presents a very low barrier to charge transfer between molecules in solution and the surface. As a test functionalization, azidomethylferrocene was coupled by "click" chemistry with the modified surface. Analysis of the redox activity highlights a surface concentration close to the maximum possible attachment considering the steric hindrance of a ferrocenyl group.