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Oligothiophene-substituted 1,1,4,4-tetracyanobutadienes (TCBDs) have been synthesized by [2 2] cycloaddition reactions between tetracyanoethylene and oligothiophene alkynes. The TCBD moiety is compared to other electron acceptors attached to dibutylterthiophene including dicyanovinyl (DCV) and tricyanovinyl (TCV). These donor−acceptor molecules (TCBD-3T, DCV-3T, and TCV-3T) show red-shifted absorption spectra relative to the unsubstituted oligothiophene as a result of intramolecular charge-transfer (ICT). Monosubstituted terthiophenes bearing the electron acceptors show both oxidation and reduction processes as characterized by cyclic voltammetry. Density functional theory (DFT) calculations are used to explain the electronic and redox properties of the materials. Electrochemical oxidation of a bis(terthienyl)-substituted TCBD molecule (3T-TCBD-3T) yields a conducting polymer exhibiting balanced ambipolar redox conduction with similar values for the oxidized and reduced states of the polymer (1 × 10−3S cm−1). Raman spectra of the asymmetric donor−acceptor materials are characterized by two intense bands characteristic of the aromatic and quinoidal regions in the conjugated π-system of the oligothiophene. [ABSTRACT FROM AUTHOR]

Direct addition of tetracyanoethylene to N-(p-hexylphenyl)dithieno3,2-b:2‘,3‘-dpyrrole yields not only the aromatic mono- and bis-tricyanovinyl-substituted products but also a quinoidal product with dicyanomethylene groups. The analogous reaction with dithieno3,2-b:2‘,3‘-dthiophene yields exclusively the aromatic mono-tricyanovinyl product. The aromatic and quinoidal products possess red-shifted absorptions, increased electron affinities, and favorable -stacking motifs in comparison to the unsubstituted oligomers. [ABSTRACT FROM AUTHOR]

Oligothiophene sulfones of up to six rings can be conveniently prepared by the direct oxidation of butyl-substituted thiophene oligomers with m-CPBA in dichloromethane. Reverse selectivity of oxidized rings is observed relative to previously reported systems without -substitution. The selectivity in the trimer and hexamer is confirmed with single-crystal X-ray structure data. The sulfones possess red-shifted absorptions and increased electron affinities relative to the parent oligomers. [ABSTRACT FROM AUTHOR]