Tailoring the electrochemical property of self-assembled monolayer of 16-mercaptohexadecanoic acid on gold (1Â 1Â 1) electrode with covalently coupling ethylene diamine

This paper reports an approach to tailor the electrochemical properties of self-assembled monolayer of 16-mercaptohexadecanoic acid (HDA) on gold electrode with covalently coupling ethylene diamine. The electron transfer kinetics of electrode varies from blocking to radial diffusion and then to linear diffusion character by controlling the surface reaction period. However, when HDA monolayer reacts with propylamine or other diamine molecules with longer alkyl chains, such as 1,6-diaminehexan and 1,4-diaminebutane, only enhanced blocking behaviors are observed. This unusual behavior is explored by a series of experiments, and a possible reaction mechanism is proposed.