1,2-Propanediol-linked chiral symmetric and non-symmetric liquid crystal dimers containing trifluoromethyl

Abstract

2016): 1,2-Propanediol-linked chiral symmetric and nonsymmetric liquid crystal dimers containing trifluoromethyl, Liquid Crystals, ABSTRACT Four symmetric and non-symmetric chiral liquid crystal dimers containing trifluoromethyl groups, termed as TFBA-PD-TFBA, UEBBA-PD-TFBA, UEBA-PD-TFBA and UEA-PD-TFBA, respectively, have been synthesised and characterised. UEA-PD-TFBA exhibited chiral nematic phase, whereas the other three dimers displayed chiral smectic A phase. X-ray diffraction (XRD) has revealed the structure of the smectic A phase for TFBA-PD-TFBA to be intercalated, whereas that for UEBBA-PD-TFBA and UEBA-PD-TFBA to be monolayer and interdigitated, respectively. In addition, the weaker peak corresponding to a shorter layer spacing was observed for UEBBA-PD-TFBA and UEBA-PD-TFBA. Considering the results of XRD measurements and computer simulations, the structural model corresponding to the shorter layer spacing is assigned as horseshoe-like shape. The absence of smectic behaviour for UEA-PD-TFBA reveals that the weaker aromatic-aromatic interactions cannot stabilise the smectic A phase. ARTICLE HISTORY

Liquid crystalline dimers containing a cholesteryl benzoate unit: smectic phase, chiral nematic phase and blue phase

“…As an important research direction in the field of liquid crystals, chirality 23,24 is introduced into molecules either by introducing chiral flexible spacers such as 1,2-propanediol 25 or by introducing chiral rigid groups such as cholesterol [26][27][28][29] and menthol, 30 etc. Cholesterol is easily obtained from nature, and its molecular structure is rigid with eight chiral cores.…”