Poly thiophene s with Pendant Reactive Groups

3 Poly(thiophene)s with Pendant Reactive Groups 

3-Methylthiophene and 3-butylthiophene can be electrocopolymerized with 3-thienylacetic acid and its methyl ester [108-110] (cf. Table 8). The COOH group is covalently bound to the copolymer structure the carboxylic group does not take part in the electrochemical reaction. 

The dimerization tendency of carboxylic acids is possibly reduced by the electrolytic conditions (cf. Sect. 5.2.2). The inductive effect (-1) of the COOH group on the thiophene system does not prevent anodic oxidation of the thiophene system [108]. 

Esterification and the consequent reduction of 3-thienylacetic acid produces 3-(2-hydroxyethyl)thiophene, which must be protected before electropolymerization. The resulting thin polymer film, e.g., of poly[3-(2-methoxyethyl)-thiophene], with protected OH groups, can be reacted to produce reactive hydroxy groups on its surface, such as poly[3-(2-hydroxyethyl)thiophene] [111] (cf. Table 3). Further thiophene derivatives with a protected OH group have been synthesized starting from 3-(2-hydroxyethylthiophene) 3-(2-benzyloxyethyl)-thiophene, 3-[2-triphenylmethyloxy)ethyl]thiophene, 3-[2-(trimethylsilyloxy)- 

Alcohol dehydrogenase can be covalently bonded on the surface of a poly-[3-(2-hydroxyethyl)thiophene] electrode by the cyanogen bromide method [111] glucose oxidase is covalently immobilized at the surface of a copolymer electrode from 3-methylthiophene and methyl 3-thienylacetate by the azide method [110] after activation of the carboxyUc groups in the copolymer of 3-methylthiophene and 3-thienylacetic acid by dicyclohexylcarbodiimide, lactate oxidase can be covalently immobilized [109]. This enzyme electrode can be used for the electrochemical analysis of lactic acid (cf. Sect. 6.9). 

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