Terthiophene

Terthiophene is the organic compound with the formula [C4H3S]2C4H2S. It is an oligomer of the heterocycle thiophene, a shorter oligomer is dithienyl, and the parent polymer is polythiophene. In the most common isomer of terthiophene, two thienyl groups are connected via their 2 positions to a central thiophene, also at the carbon atoms flanking the sulfur.

Preparation of terthiophene
Terthiophene is prepared by coupling 2,5-dibromothiophene with the Grignard reagent derived from 2-bromothiophene.

Properties and applications
This isomer is a pigment in marigolds and exhibits some biological activity because is sensitizes the formation of singlet oxygen, which is often lethal. A variety of terthiophenes occur naturally, including 5,5 '' -dichloro-&alpha;-terthiophene, 5-chloro-&alpha;-terthiophene, 5-acetyl &alpha;-terthiophene, and 5-carboxyl bithiophene.

Terthiophene have been employed as building blocks for the organic semi-conductor polythiophene.