Electrochemical and Spectroscopic Characterization of Self-Assembled Monolayers of Ferrocenylalkyl Compounds with Amide Linkages

Short chain ferrocenylalkyl disulfides, where n < 9, with the amide functionality (−OCN) at variable positions were synthesized and self-assembled on vapor-deposited gold. The effects of interchain hydrogen bonding on the stability, packing density, electron transfer rate and the formal potential of these self-assembled monolayers were investigated using cyclic voltammetry and infrared reflection−absorption spectroscopy. Interchain hydrogen bonding appeared to enhance the stability of these monolayers, although the packing densities were lower than that expected for a full monolayer. The electrochemical behavior of coadsorbed monolayers of ferrocenylalkyl disulfides and nonelectroactive unsubstituted alkanethiols was also examined. In these coadsorbed systems, an unexpected negative shift in the formal potential of the ferrocenyl compounds with the amide linkages was observed. This was attributed to disorder arising from the disruption of the hydrogen bonds within the monolayer caused by the alkanethiol “...