Helical superstructure from an achiral banana-shaped liquid crystal

Abstract

In the banana-shaped achiral molecular system reported here, 1,3-phenylene bis[4-(3-chloro-4-n-octyloxy-phenyliminomethyl) benzoate] (PBCOB) and 1,3-pbenylene bis[4-(3-fluoro-4-n-octyloxy-phenyliminomethyl) benzoate] (PBFOB), their smectic mesophases, including a switchable banana phase B,, were identified by differential scanning calorimetry (DSC), X-ray scattering and polarizing optical microscopy (POM) studies. Both the left-and right-handed helical domains are spontaneously formed upon cooling from isotropic liquid to the switchable banana phase (B7). The homeotropic alignment and ferroelectric properties of banana-shaped liquid crystal are investigated. The spontaneous polarization for PBCOB is about 50 nC/cm2. Doping the PBCOB with a cyanohydrin-contain chiral smectic liquid crystal resulted in more right-handed helical structures.

New banana-shaped mesogens with bromine-substituted central core

“…The outer rings can [1]. Together with a tilt of the molecular long axis, the most probably be substituted without loss of the liquid symmetry breaking can lead to chiral discrimination crystalline properties [7][8][9]. The disturbing eOE ect seems to [2].…”

Preliminary communication Helical superstructures in a novel smectic mesophase formed by achiral banana‐shaped molecules

“…This phase also exhibits helical nuclei and a domain morphology quite similar to the original B 7 phase [9,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. The B 7 9 phase has been reported for bent mesogens with quite different structures.…”

Banana‐shaped and other bent‐core liquid crystals

“…Compound 29 has two outer-edge lateral fluoro substituents which results in a only a slight reduction in B2 phase stability when compared with the unsubstituted parent system (compound 14), but note the original transition temperatures (second set listed) of Lee and Chien [34], which differ considerably from those used in the comparison [35]. However, the analogous inner-core fluoro-substituted material (30) [35] has a much reduced B2 phase stability, and the larger lateral methyl substituents (compound 31) [35] have a massive reducing effect on the B2 phase stability.…”