Reactive groups on polymer coated electrodes, 12. New conducting carrier materials: polyalkylthiophene functionalized with amino group and its protected forms

The synthesis and electropolymerization of 3-alkylthiophenes functionalized with a terminal amino group and its protected forms are reported. As expected, due to the strong electronic interference of the amino group, the electropolymerization of the unprotected monomer is fully inhibited. After protection of the amino group the polymerizability of the corresponding monomers is considerably improved; however, the successful polymerization process clearly depends on the nature of the used protective group. Only such monomers in which the nucleophilic character of the amino group is strongly suppressed by a suitable proctective group undergo electropolymerization to form the corresponding electroactive polymers. The obtained polymers are electrochemically stable and, besides the typical properties such as redox behavior and electrochromism, they exhibit a distinct solvatochromic behavior. Electrical conductivity measurements on their oxidized forms by means of the two-probe method give values in the range of 10 -3 to 10 -2 S . cm -1 . The feasibility of using the resulting polymers as conducting carrier materials was demonstrated by the removal of the protecting groups and the subsequent attachment of a redox active ferrocene compound. Electrochemical and spectroscopic experiments confirmed that after the polymer analogous reaction the used redox active ferrocene model compound is covalently immobilized onto the polymer surface and the electroactivity of the bonded redox groups as well as the carrier materials is retained.