Ferrocenylalkylthiolate labeling of defects in alkylthiol self-assembled monolayers on gold

Abstract

Coverage defects in alkylthiol self-assembled monolayers (SAMs) are critically important to function related to electron transfer from soluble redox probes. There is therefore a need for an accurate and direct measurement of the number and type of coverage defect in a range of SAMs. Ferrocenyldodecanethiol (FcC₁₂SH) has been assessed as an electrochemically-addressable label of coverage defects. It is shown that short time exposure of a SAM to FcC₁₂SH leads to a quantifiable Fc coverage (Γ_Fc), with Γ_Fc < 1% readily measurable. The voltammetric signature of FcC₁₂SH label is also able to differentiate types of defect in a given SAM. A number of SAM preparation conditions are assessed for the density and type of coverage defect. This labeling method therefore will be a useful tool for research into SAM property–function relationships.