Electroactive redox pairs

According to Holze [135], the redox pair (iipa = 0.32 V and = 0.28 V) that can be seen in Fig. 4.12a is related to the copolymer, as neither PANI nor POAP show such voltammetric peaks. The brownish-blue color of the polymer film obtained at a concentration ratio of 1 10 also differs from that of the monopolymers. The color of the films formed at other concentration ratios was yellow. The synthesized poly(aniline-co-o-aminophenol) was found to be electroactive, even at pH 10, and its conductivity was decreased by three orders of magnitude compared to PANI. 

CV measurements of the modified brushes showed the typical electrochemical response corresponding to a surface-confined electroactive species and the redox counterions, as ferriq anide species form stable ion pairs with the quaternary ammonium groups of the brush (Fig. 4.6] [47]. In a noncovalent way, Mao et al. have reported that ILs could be directly immobilized on the glassy carbon electrode (GC] by casting and observed the electrocatalytic activity toward ascorbic acid (AA] and the capability to facilitate direct electron transfer of horseradish peroxidase (HRP] (Fig. 4.7]... 

It should be mentioned that few, if any, examples are known of carbon-containing species chemisorbed at electrodes that are directly electroactive like H or OH/O species. Only in the case of adsorbed quinones or polymer-bound redox functions at chemically modified electrodes is direct surface electroactivity known. Some organic sulfide/disulfide pairs such as cystine/cys-teine are also electroactive when adsorbed. 

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