The effect of the self-assembled n-alkanethiol monolayer formed onto a gold surface on the voltammetric responses of flavin adenine dinucleotide (FAD), ubiqainone-0 (2,3-dimethoxy-5-methy1-1,4-benzoquinone, UQ0), and Fe(CN)3−6 has been investigated in relation to the permeability of these species. In contrast to the Fe(CN)3-6 ion that was practically unable to permeate into the alkanethiol monolayer assembly, FAD and UQ0 molecules were found to permeate more easily into the monolayer assembly. The apparent heterogeneous rate constant, k0, of Fe(CN)3−6 decreased exponemially with the chain length of the modified alkanethiols. The dependence of the k0 value of FAD on the chain length showed the deviation from exponential decay. In contrast, the k0 value of UQ0 was found to be scarcely affected by the chain length of the modified alkanethiols. The differences in the dependence of the k° values on the chain length were attributed to the differences in the permeability of these redox species into the hydrophobic monolayer assembly of the alkanethiols.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films
- Colloid and Surface Chemistry