Aromatic compounds electropolymerization

A variety of other aromatic compounds have been successfully electropolymerized and found to have the general electroactive properties described for the polyaniline, polypyrrole and polythiophene films. Films have been prepared from azulene furan, indole , carbazolepyrenetriphenylene and phenylene (see Scheme 1). In principle, all of these films could be used as electrodes in energy... 

The mechanism proposed for the electropolymerization of heterocycles by anodic coupling (Figure 4.3) [15] is analogous to the already known coupling of aromatic compounds [16,17]. The first step consists of the oxidation of the monomer to its radical cation. The second involves the coupling of two radical cations to produce a dihydrodimer dication which leads to a dimer after loss of two protons and rearomatization. Due to the applied potential, the dimer, which is more easily oxidized than the monomer, occurs in its radical form and undergoes a further coupling with a monomeric radical. 

A mechanism involving the coupling of cation radicals has also been considered for the electropolymerization of benzene compounds [306,313]. This mechanism occurs by a sequence of events similar to those proposed for the electropolymerization of pyrroles. The first step is the oxidation of benzene to a cation radical (471). Two of these cation radicals combine to form a dication dimer (478). The neutral aromatic dimer (479) is formed upon loss of two protons. This dimer is then reoxidized to a cation radical (480). Chain growth is accomplished by the coupling reaction of this cation radical with other cation radicals followed by deprotonation to form aromatic structures. Polymer growth continues by this sequence of steps until precipitation from solution occurs (Fig. 72). 

R. J. Waltman, A. F. Diaz, J. Bargon, Substituent effects in the electropolymerization of aromatic heterocyclic compounds, Journal of Physical Chemistry 1984, 88, 4343. 

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