| Abstract
| - We have identified a simple experimental protocol to assemble electroactive films with attractive electrontransport properties on gold electrodes. Their basic building block is a bipyridinium bisthiol, which adsorbsspontaneously on the electrode surface forming multiple electroactive layers. The resulting interfacial assembliesmediate the transfer of electrons from the electrode to redox probes in the electrolyte solution but preventelectron transfer in the opposite direction. After the insertion of electroactive anionic dopants in the polycationicbipyridinium matrix, the transfer of electrons from the redox probes to the electrode becomes possible. Underthese conditions, the probe reduction accompanies that of the surface-confined bipyridinium dications, whilethe probe reoxidation follows the oxidation of the anionic dopants. This intriguing behavior imposes a largepotential difference between the voltammetric reduction and oxidation peaks of the probe, which parallelsthe difference between the bipyridinium reduction and the dopant oxidation potentials. Thus, the careful selectionof the electroactive dopant can be exploited to tune the electronic properties of the composite film. Thischemical approach to interfacial assemblies with controlled dimensions and engineered properties can lead toelectrode/organic film/electrode junctions with predefined current/voltage signatures.
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