A novel monomer candidate for intrinsically conductive organic polymers based on nonclassical thiophene

We have prepared and characterized a series of mixed trimers composed of aromatic heterocycles and a novel nonclassical thiophene with pyrazine-dihydropyrazine redox system. The oxidized forms of these compounds have much lower optical and electrochemical energy gaps compared to the related compounds. Especially the pyrrole derivative showed a 1000 nm red shift of the absorption band compared with terthiophene; the lowest-energy absorption maximum and the absorption edge were observed at 1345 nm (0.92 eV) and 2100 nm (similar to 0.6 eV), respectively. The anodic oxidation of the pyrrole derivative gave the electroactive polymer exhibiting a vanishingly small electrochemical energy gap.