Thienylenevinylene oligomers (nTVs) containing up to 10 thiophene rings and bearing solubilizing hexyl groups at the α-position of the end thiophene rings or octyl or dibutyl chains at the 3-position or the 3- and 4-positions of the thiophene rings have been synthesized by a combination of formylation reaction, Wittig−Horner olefination, and McMurry dimerization. Owing to the good solubility imparted by alkyl chains, the electrochemical behavior of nTVs has been analyzed for the first time. Chain extension leads to a negative shift of the peak potentials corresponding to the formation of the cation radical and dication and to a decrease of their difference. For the octamers the dication is formed directly through a two-electron transfer while the system can be reversibly charged up to the tetracationic state. Electronic absorption spectra show the expected bathochromic shift of λmax and decrease of the HOMO−LUMO gap with extension of the conjugation length. Thus, solution-cast films of octamers exhibit band-gap values comparable to or even smaller than that of the parent poly(thienylenevinylene) (PTV). Extrapolation of the electrochemical and optical data to infinite chain length suggests that the oxidation potential and intrinsic band gap of a defect-free PTV could be significantly smaller than the present experimental values.

The control of the bandgap of thiophene‐based polymers and oligomers has become an important topic in recent years. One strategy is the introduction of electron‐withdrawing groups in particular positions in the conjugated chain. An extension of this strategy is reported here: the synthesis and electrochemical investigation (e.g., analysis of the electropolymerization behavior) of a new series of π‐conjugated oligomers containing 3, 4, and 5 heterocycles and two CN groups at various positions of the ethylene linkage.

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Rigidification of E-l,2(2,2'-dithienylethylene) by bridging the thiophene rings with the central double bond leads to a ca. 0.40 eV decrease of the bandgap of the resulting conducting polymer.

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A series of three dicyanovinyl (DCV)-substituted oligothiophenes (referred to collectively as DCV-nT-DCV, where n = 1-3) were prepared and their electrochemical and structural properties were examined. The introduction of this group results in favorable structural features: planarity, π-stack formation, and close intermolecular interactions as revealed from X-ray single crystal analysis. Electrochemical measurements suggest that these molecules are easy to both oxidize and reduce and thus are expected to show ambipolar charge transport properties similar to those we reported earlier on a closely related series of oligthiophenes endowed with the tricyanovinyl group (TCV).

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