Novel chiral liquid crystal with two chiral butyl lactate chains exhibiting several frustrated mesophases including smectic Q and TGB phases separated by an optically isotropic phase

Abstract

A novel symmetric liquid crystalline compound with two chiral butyl lactate chains, (S,S)-bis[4-(1butoxycarbonyl)ethyloxycarbonyltolanyl]fumarate (BisBLOCTF), was synthesized. This compound was found to exhibit a very unusual phase sequence involving several frustrated mesophases, namely smectic Q, TGBC, TGBA and blue phases. In addition, an ''optically isotropic'' phase occurs between the smectic Q and the SmC*, and TGB phases. The different phases were studied by optical observation, DSC, X-ray diffraction and helical pitch measurements. Changing the nature of the chiral chains reduces the sequence to only a smectic Q mesophase.

Toward rational design of complex nanostructured liquid crystals

“…From a molecular structure viewpoint, the characteristics of the chiral part of the azo‐dichiral molecule are important because all known compounds exhibiting the SmQ phase typically have the same chiral part structure,22–24,30–34 such as that of compounds 17 (Fig. 2), 18 , and 19 (Fig.…”

New compounds with a TGBA-TGBC-SmC* phase sequence

“…The anomalies detected at the TGBA-TGBC phase transition are slightly higher than the characteristic values usually found. Nevertheless, some compounds have been reported with comparable high enthalpy values at this phase transition [23,24]. The phase transition between the TGBC and SmC* phases exhibits a strong hysteresis.…”

New chlorine‐substituted liquid crystals possessing frustrated TGBA and SmQ phases

“…A rare re-entrant ferroelectric phase and the ferroelectric hexatic phase have been found in some of these materials (4). Additionally, the presence of the second and third lactate units in such a molecule leads to a decrease of the phase transition temperatures in comparison with an analogous molecule with only one lactate group (2,3). A very broad SmC* phase was found in materials with a molecular core possessing one biphenyl moiety substituted by chlorine, two more aromatic rings connected by the ester linkage and a chiral part containing one lactate group (5).…”

“…Recently, it has been found that materials with three phenyl rings in their molecular core and a chiral part based on the lactate unit possess a ferroelectric chiral smectic C (SmC*) phase (1)(2)(3) and, in the case of two lactate units, a tendency to form the antiferroelectric chiral smectic C (SmC A *) phase has been discovered (2,4). A rare re-entrant ferroelectric phase and the ferroelectric hexatic phase have been found in some of these materials (4).…”

“…We intended to remove the ester group and prepare a more rigid molecular core, which could diminish the transition temperatures. Multiple lactates have been used to increase the probability of the occurrence of an antiferroelectric phase (2)(3)(4). Taking into account the above-mentioned knowledge, three series with one, two or three lactate units in the chiral part and with a varying length of the non-chiral chain have been synthesised.…”