Electrochemical investigation of regioregular alkyl substituted oligothiophenes

Radical cation stabilities and their dimerization reactions have been studi ed through the series of regioregular oligothiophenes (n = 2-6 where n is t he number of thiophene rings) with chlorine protected at one alpha-terminal position. The oligomers with two and three rings undergo one oxidation rea ction to produce the radical cations, oligomers with four, five and six rin gs undergo two stepwise oxidations to produce the radical cations and dicat ions, respectively. The radicals coupled to form dimers in following reacti ons. Based on double-potential-step data we observed that the dimerization rate decreases as n is increased. This result suggests that the stability o f the radical increases with increasing size of its oligothiophene chain. ( C) 2000 Elsevier Science Ltd. All rights reserved.