Synthesis and electronic properties of 4-cyanophenylvinylenedithiathiophene: An EDOT derivative

Synthesis of 4-cyanophenylvinylenedithiathiophene, which is an analogue of ethylenedioxythiophene (EDOT), has been described. The synthesis was achieved by applying 1,8-diketone ring formation reaction occurring between 1,8-diketone and phosphorus decasulfide in boiling toluene. The target compound was characterized by cyclic voltammetry (CV), UV spectroscopy, and theoretical studies. Unlike the analogues similarly carrying phenyl groups substituted with other functional groups such as –OMe, –Br, –NO2, neither electrochemical polymerization attempts nor chemical polymerization efforts with ferric chloride(III) (FeCl3) succeeded in yielding any products. Results of spin density calculations revealed that the molecule did not have enough electron spin densities at the “α” carbons of the thiophene part. Moreover, during the polymerization attempt with FeCl3, as the nitrile nitrogen could form complex with iron, spin density calculation was also performed for protonated form of the monomer, which indicated that the “α” carbons of the molecule had even lower spin densities.

► 1,8-Diketone reacting with P4S10 gives 4-cyanophenylvinylenedithiathiophene.
► Neither electrochemical nor only chemical polymerization attempts succeeded.
► More negative spin densities at “α” carbons of thiophene part.