Extensive quinoidal oligothiophenes with dicyanomethylene groups at terminal positions as highly amphoteric redox molecules.

A series of highly extensive quinoidal oligothiophenes carrying a dicyanomethylene group at both terminal positions is synthesized. As the quinoidal structures extend, they have highly amphoteric abilities and show strong electronic absorptions in the visible to near-infrared region. The higher homologues, quinquethiophene and sexithiophene, exist as equilibrium mixtures with the biradical species.