Synthesis of new wide nematic diaryl-diacetylenes containing thiophene-based heteromonocyclic and heterobicyclic structures, and their birefringence properties

Abstract

New monocyclic and bicyclic thiophene-based diaryl-diacetylene liquid crystal (LC) materials were synthesised and demonstrated to exhibit wide enantiotropic nematic phases. One thiophenyl-benzene derivative, in particular, displayed a stable nematic phase across a temperature range of over 100°C. The birefringence properties of the compounds were measured using a multiple-beam interference (MBI) method, with the highest value found to be for the same thiophenyl-benzene molecule (Δn = 0.57, 550 nm) at 10°C above the crystal-to-nematic transition temperature. Furthermore, the effects of the cyclic structure on the mesomorphic behaviours, transition temperatures, and birefringence properties were investigated in detail from both experimental and theoretical viewpoints.

Keywords:

• diacetylene
• thiophene
• birefringence
• nematic phase

Supplemental data

Synthetic procedures, spectral data, NMR, birefringence properties on wavelength dependence, CV charts.

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