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 ( ~0.6 eV), respectively. The anodic oxidation of the pyrrole derivative gave the electroactive polymer exhibiting a vanishingly small electrochemical energy gap.