New class of 2,5-di(2-thienyl)pyrrole compounds and novel optical properties of its conducting polymer

New type 2,5-di(2-thienyl)pyrrole derivative namely 4-amino-N-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)benzamide (HKCN) have been synthesized via reaction of 1,4-di(2-thienyl)-1,4-butanedione and p-aminobenzoyl hydrazide. Using hydrazide instead of amine not only increases product yield but also improves properties of the corresponding polymer. Spectroelectrochemical investigations revealed that P(HKCN) is more stable and it has lowest band gap and better long-term stability compared with other SNS derivatives. Chronoamperometry experiment showed that P(HKCN) polymer film has excellent redox stability, moderate switching time and high optical contrast. Electrochemical copolymerization of HKCN with EDOT was performed in DCM/TBP6 solution for different feed ratios of monomers. We describe a proposal to determination copolymer composition by means of the optical properties of conducting copolymers.