Electropolymerization ferrocene/thiophene conjugates

The electropolymerization of ferrocene/thiophene conjugates [65] was conducted by oxidation on a Pt electrode and led to the deposition of a monolayer of poly (thiophene). The electropolymerization was performed from several solution systems, such as tetrabutylammonium hexafluorophosphate/acetonitrile and lithium perchlorate/acetonitrile, at a concentration of 0.1 M. Constant potential experiments (+ 2.0 V) for a definite time were used to effect polymerization. Polymerization was also attempted using cyclic voltammetry (repeatedly sweeping from 0.0 to + 2.5 V) and pulse potential (potential stepped from 0.0 to 2.0 V and back to 0.0 V). 

In the characterization of electropolymerization products from ferrocene/thiophene conjugates, however, it was shown that they are relatively unstable to repeated potential cycling between 0.0 and +1.0 V and are quickly destroyed at potentials of + 2.0 V or more. The system appears to have an intrinsic limit to the amount of polymer that may be deposited onto the electrode surface. This may be rationalized to arise from the cationic state of ferrocenium when the oxidation potential of thiophene monomer is reached. Surface coverage calculations show that this limit corresponds to about a monolayer of ferrocene groups. 

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