Study on the intermolecular interactions between the functional moieties in ferrocene-terminated alkanethiol self-assembled monolayer on gold

In this paper, we used two kinds of ionic surfactants, sodium dodecylbenzene sulfonate and cetyltrimethylammomium bromide, to explore how the intermolecular interaction affected the electrochemical behavior of 11-Ferrocenylundecanethiol (HSC11Fc) self-assembled monolayers (SAM). While HSC11Fc was mixed with octanethiol in a low mole ratio, we found a well-defined redox wave. After the treatment with both surfactants, a shoulder peak more positive to the main wave emerged. This observation was explained with the variation of the local microenvironment as evidenced by the reorganization energy. Without the surfactant interaction, the pure HSC11Fc SAM also exhibited the similar shoulder peak, which can be further enhanced by the treatment with the surfactants. By gradually changing the surface coverage of ferrocene moiety, it proved that the shoulder peak was originated from the intermolecular interaction by either the ionized surfactant or the neighboring ferrocenium ions.