Liquid crystalline benzothiophene derivatives. Part 2: 2,5-disubstituted benzothiophenes

Abstract

In the continuation of our study on heterocyclic mesogens, the structural motif of a 2,5-disubstituted benzothiophene as the central unit was utilised to design novel liquid crystals. Despite the bent molecular structure, the formation of a standard calamitic phase was observed. The mesomorphic properties of the model substances of series I was very close to that of the previously studied 6-substituted derivatives. Introduction of the chiral terminal unit led to appearance of the ferroelectric smectic C* (SmC*) phase in compounds IIa–d. 5-Phenylbenzothiophene based mesogens III exhibited higher clearing temperatures and polymorphism (nematic–smectic A–SmC sequence). Thus, the central benzothiophene unit can be successfully utilised in the design of various liquid crystals.

Keywords:

• liquid crystals
• 2,5-disubstituted benzothiophene
• calamitic phases
• mesomorphic properties

Acknowledgements

This project was supported by the Czech Science Foundation (project no. 202/09/0047 and P204/11/0723) and the Ministry of Education, Youth and Sports of the Czech Republic (project no. MSM6046137301).