Synthesis of electrically conducting poly{2,2'-[5,5'-(1,2-ethynediyl)] bisthiophene}

摘要

Thiophene can be polymerized easily, either chemically or electrochemically, to form an environmentally stable, conjugated polymer dopable to high conductivity [-1]. The presence of conjugative spacer groups such as -C=C- in the polymer backbone have also been shown to afford conducting materials. Thus, poly(2,5-thienylenevinylene) (compound 1) synthesized chemically was found to have a generally higher conductivity (37-63 S cm"1) and lower band gap (1.74 eV) than polythiophene [2,3]. With this in mind, it would be interesting to investigate the effects of an ethynyl conjugative spacer between the arylene groups. We report here the chemical synthesis of poly{2,2'-[5,5'-(l,2-ethy-nediyl)] bisthiophene} (compound 2), which was dopable to a highly conducting state. In contrast, previous efforts to synthesize the polymer yielded only samples with a low conductivity (1.6 X 1(T7 Scnr1) [4], while the related poly(2,5-thienyleneacerylene) (compound 3) was non-conducting [5].