Electron tethered redox probe

To probe the microscopie order of SAMs (here we will treat only nonelectroactive SAMs those containing tethered redox probes will be discussed later) under the conditions used during electrochemieal electron-transfer measurements, functional characterization is performed by cyclic voltammetric techniques. In this subsection, electrochemical blocking effect EBE) and double-layer capacitance (Cai) experiments are detailed. When these experiments are carried out using a struetural probe of molecular scale [30, 44, 45], they provide the greatest sensitivity to defects because the effects of defects and disorder dominate the electrochemical response. 

In electrochemical experiments, the molecular assembly is deposited on a conductive electrode surface that acts as one of the redox partners . The other partner is a redox molecule either tethered to the molecular film or free in solution. In either case, the film ideally provides a well-defined separation between the electrode and the redox probe. The electrode potential is either swept or stepped to increase the driving force for electron transfer. The chief advantage of the electrochemical elec-... 

Mediation of electron transfer between a dissolved redox probe and the electrode by surface-confined redox groups has also been used to assess the integrity of electroactive monolayer assemblies. As an example, the reduction of Ru (NH3)e, normally occurring at about 0.1 V vs. Ag/AgCl, is fully blocked by an assembly containing tethered A-ethylviologen redox probes. However, at the observed reduction potential of the viologen probes (ca. —0.4 V), these probes mediate the reduction of Ru (NH3)g [87]. Similarly, the delayed oxidation of Fe (CN)6 at... 

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