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A novel amperometric electrode based on a conducting polymer is presented and its properties are compared with those of a glassy carbon electrode. The electrode material was made by mixing 25-dimethoxy-1,4-bis[2-(3,4,5-trimethoxy-phenyl)ethenyl]benzene with iodine and polycarbonate. The blend was coated on a glassy carbon electrode by evaporation from a chloroform solution. Catecholamines were used as test substances in LC and FIA measurements. They were oxidized at a potential of +0.7 V (vs. SCE). The electrode exhibited a linear response for injected concentrations from 2.5 x 10-6M to 2.5 x w 3 M . It had a response time of 1.2 s and a coulometric efficiency of 0.74 % at a linear flow rate of 1 mL/min. The electrode material is stable for several months under normal operating conditions. Hydrodynamic voltammograms showed E,,, values shifted by approximately 100 mV as compared to glassy carbon. The novel redox-conducting coating is proposed as an alternative material for the development of enzyme electrodes and chemically modified electrodes.

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The new polymer poly(thiophene-2,5-diyl-1,2-dimethoxyvinylene) was synthesized by a benzoin condensation of thiophene-2,5-dicarboxaldehyde to poly(2,5-thienylene-1-oxo-2-hydroxyethylene) (M w ∼ 1 × 106, pd ∼ 13), followed by O-alkylation using dimethyl sulfate. A side reaction of the benzoin condensation step leading to dimethyl-2,5-thiophenedicarboxylate can be avoided by using cyclohexanol as the solvent. The O-alkylation, including the workup, has to be performed under nitrogen protection to counteract the degradation of the polymer by air under the influence of light. A mechanism is proposed for the oxidative degradation of this poly(thiophene-2,5-diylvinylene) derivative and other poly(arylenevinylenes). Conductivity and thermal properties of the new polymer are given.