Synthesis and Properties of Dihexylbithienoquinonoid Derivatives with Head-to-head, Head-to-tail, and Tail-to-tail Orientations

Abstract

2,2′-(Dihexyl-2,2′-bithienylidene-5,5′-diylidene)bis(propanedinitrile)s (dihexylbithienoquinonoid derivatives), in which two 3-hexylthiophene moieties are connected with head-to-tail (HT) and tail-to-tail (TT) orientations, were synthesized. HT bithienoquinonoid was isolated in a single form together with a small amount of its bromo derivative, similarly to the case for the head-to-head (HH) orientational isomer. On the other hand, TT isomer exhibited a peculiar feature in solution, affording an equilibrium mixture of two geometrical isomers. Electronic and electrochemical properties of these bithienoquinonoids were studied and compared with those of HH isomer. The results proved that all these bithienoquinonoid compounds possess highly polarizable and electron-acceptable properties. HH bithienoquinonoid was reduced through one two-electron transfer process, while HT and TT isomers were reduced through two one-electron transfer processes via stable radical anions to the corresponding dianions.

Oligothiophene quinoids containing a benzo[c]thiophene unit for the stabilization of the quinoidal electronic structure

“…Similar anti-syn equilibrium was also reported on tetracyano bithiophene quinoid at 25 1C. 19 These results indicate that the quinoidal electronic structures of BTQ and BTQ-F are stabilized owing to the reduced contribution of the biradicaloid structure by benzene annulation. In addition, the presence of fluorine atoms on the thiophene rings in BTQ-F induces not only steric congestion in the syn form but also intramolecular S-F attractive interactions, forming fixed anti configurations between adjacent thiophene rings.…”

Spectroscopic and Theoretical Study of the Molecular and Electronic Structures of a Terthiophene‐Based Quinodimethane

“…Bu 2 (DCM) 2 Tth and other related oligothienoquinoid systems12, 27, 32, 33 can be viewed as structural and electronic models of dication species in oxidized oligothiophenes. Oxidation of aromatic oligothiophenes leads to the appearance of quinoid structures growing up from the center of the oligothiophene chain at the expense of the aromatic structure.…”

Quinoidal bisthienoisatin based semiconductors: Synthesis, characterization, and carrier transport property

“…Separating the mixture of E / Z ‐isomers by silica gel column chromatography was difficult due to their rapid isomerization at room temperature, which is consistent with the previous studies. [ 24‐27 ]…”