Synthesis and properties of head-to-head, head-to-tail, and tail-to-tail orientational isomers of extended dihexylbithiophene-octaethylporphyrin system [OEP-(DHBT)(n)-OEP] connected with 1,3-butadiyne linkages

An extended pi -electronic conjugation system of dihexylbithiophene-octaeth ylporphyrin [OEP-(DHBT)(n)-OEP; n = 1-5], all the chromophores in which are connected with the linkage of 1,3-butadiyne (diacetylene), was synthesized by an oxidative cross-coupling reaction of the corresponding terminal acet ylenes. Absorption spectral and electrochemical properties of the OEP-(DHBT )(n)-OEP system were examined. The results proved that the orientation of t wo 3-hexylthiophene (3HTh) rings of DHBT plays an important role in electro nic communications between the two terminal OEP rings.