Surface-confined monomers on electrode surfaces Part 3. Electrochemical reactions and scanning probe microscopy investigations of ω-(N-pyrrolyl) alkanethiol self-assembled monolayers on gold

The formation and subsequent polymerization of ω-(N-pyrrolyl)alkanethiol monolayers on polycrystalline gold under various conditions was performed. Polymer formation in the monolayer is suppressed by addition of H2O or pyridine to the Bu4NClO4-CH3CN or Bu4-propylene carbonate (PC) electrolyte. Exposure of gold electrodes to ethanol solutions of n-hexanethiol and N-(6-mercaptohexyl)pyrrole results in monolayers which do not reflect the composition of the dosing solution. The presence of 75% n-hexanethiol in the assembly solution results in mixed monolayers which still display surface-confined pyrrole oxidation, but no voltammetric evidence for polymer formation. Scanning tunneling microscopy of the oxidized monolayers on Au(111)/mica yields images which are not substantially different from those of the unoxidized monolayers on Au(111)/mica.