Electrochemical and topological characterization of gold(111) ∣ oligo(cyclohexylidene) ∣ gold nanocrystal interfaces

Self-assembled monolayers (SAMs) of functionalized oligo(cyclohexylidene) molecules on gold(111) surfaces have been studied by measurement of the interfacial capacitance in concentrated electrolyte solutions and by cyclic voltammetry with Fe(CN)63−/4− as the redox system. The morphology of the layers has been studied by scanning tunneling microscope (STM) and AFM. We found that sulfide-terminated oligo(cyclohexylidenes) form a well-ordered SAM on gold(111) and that the oxime end-functionality inhibits the formation of ordered SAMs. Charge-stabilized gold nanocrystals attach to sulfide-terminated SAMs on gold(111) to form robust gold(111) ∣ oligo(cyclohexylidene) ∣ gold nanocrystal molecular junctions. We show that the nanocrystal ∣ water interface can be charged by electron transport through the molecular layer.