Mechanism of Spontaneous Formation of Monolayers on Gold from Alkyl Thiosulfates

The kinetics of adsorption of self-assembled monolayers (SAMs) from solutions of hexadecyl thiosulfate in tetrahydrofuran was studied under a variety of experimental conditions to elucidate the mechanism(s) important in this process. Monolayers did not form in the absence of water, which ruled out the direct addition of the alkyl thiosulfate to the gold surface and implicated hydrolysis as a route to surface-active adsorbates. The role of tetrafluoroborate ion, known to inhibit SAM formation in this system, was also examined. These studies, too, were consistent with hydrolysis as an intermediate step in the formation of monolayer films in this system.