Ferrocene units redox-active monolayers

A number of conjugated 2D pol3mers are electrically conducting and offer promise for application in molecular electronics, a field that pushes the goal of miniaturization to the ultimate extreme. Self-assembled monolayers (SAMs) can be assembled on a gold electrode and the other end of the molecular wire probed with a Au tip of a conductive atomic force microscope (CAFM) for the conductivity measurement. An organometallic example is shown in Fig. 13.8, where conductivity is much enhanced by the presence of the redox-active ferrocene units. ... 

A further approach to controlling electrical communication between redox proteins and their electrode support through a photo-command interface includes photo stimulated electrostatic control over the electrical contact between the redox enzyme and the electrode in the presence of a diffusional electron mediator (Scheme 12).[58] A mixed monolayer, consisting of the photoisomerizable thiolated nitrospiropyran units 30 and the semi-synthetic FAD cofactor 25, was assembled on an Au electrode. Apo-glucose oxidase was reconstituted onto the surface FAD sites to yield an aligned enzyme-layered electrode. The surface-reconstituted enzyme (2 x 10-12 mole cm-2) by itself lacked electrical communication with the electrode. In the presence of the positively charged, protonated diffusional electron mediator l-[l-(dimethylamino)ethyl]ferrocene 29, however, the bioelectrocatalytic functions of the enzyme-layered electrode could be activated and controlled by the photoisomerizable component co-immobilized in the monolayer assembly (Figure 12). In the... 

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