Twenty liquid crystals both symmetrical and non-symmetrical bistolanes with terminal alkyl, alkoxy and alkylsulfanyl chain and lateral methyl or ethyl group have been synthesized via Sonogashira cross-coupling and their mesomorphic properties have been studied. Most compounds exhibit an enantiotropic nematic phase in a broad temperature range (>40 °C). Optical properties of selected compounds have been investigated. They exhibit a high value of birefringence (>0.4).

For a newly designed binary liquid crystalline system we report the induction of two stable twist grain boundary (TGB) phases, namely the orthogonal paraelectric TGB smectic A* (TGBA*) and tilted ferroelectric TGB smectic C* (TGBC*) phases, within a quite broad temperature range. The designed binary mixtures consist of a highly tilted chiral ferroelectric compound, (S)(+)-4′-(ω-alkanoyloxy)alkoxybiphenyl-4-yl-4-(1-methylheptyloxy) benzoates (2H6R) and an achiral hockey stick-shaped compound (H-22.5). Measurements of optical transmission intensity, static permittivity (ε_‖, ε_⊥), spontaneous polarization (P_s), torsional bulk viscosity (η) and dielectric spectroscopy have been carried out for all the mixtures and the pure chiral compound. Possible outcomes and related transitional phenomena have been discussed from the viewpoint of perturbation introduced by the achiral hockey stick-shaped molecules. Dielectric studies reveal a sign inversion (positive to negative) of the dielectric anisotropy for all the mixtures including the pure compound. By increasing the concentration of achiral hockey stick-shaped compound, it is possible to increase the temperature range of the positive dielectric anisotropy. On the other hand, the measured values of spontaneous polarization in the TGBC* phase for the mixtures are considerably lower than that of the SmC* phase for the compound 2H6R; conversely, the response time and effective torsional bulk viscosity for the mixtures possess a higher value than that of the SmC* phase of the pure 2H6R compound. Additionally, the frequency-dependent dielectric spectroscopy measurement reveals that the relaxation frequency and dielectric strength of the Goldstone mode in the TGBC* phase slightly decreases compared to the SmC* phase of the pure compound due to the addition of the H-22.5 dopant.

The recent discovery of a new ferroelectric nematic (N_F) liquid crystalline phase has become of utmost interest for the liquid crystal (LC) and the whole soft and condensed matter fields. Contrary to the previously known ferroelectric LC materials, whose ferroelectric characteristics were much weaker, new polar nematics exhibit properties comparable to solid ferroelectrics. This discovery brought about tremendous efforts to further explore compounds showing these phases, and fascinating physical properties have been reported. Herein, we present the first synthesized compounds with the enantiotropic ferro- (N_F) and antiferroelectric (N_X) nematic phases. The enantiotropic nature and an unprecedentedly broad temperature range of N_F and N_X phases are confirmed by various experimental techniques: polarized-light optical microscopy (POM) observations, different scanning calorimetry (DSC), dielectric spectroscopy, second harmonic generation (SHG), and molecular modeling. The presented achievements in designing achiral compounds that exhibit enantiotropic polar nematic phases with ferro- and antiferroelectric properties significantly contribute to the development of multicomponent mixtures with a broad temperature range of N_F and N_X phases down to room temperature. Furthermore, this accomplishment considerably enhances the general understanding of the structural correlations that promote polar nematic liquid crystal phases with high thermodynamic stability. Finally, this work may benefit various applications in photonic devices.

Five homologous series of (S)-(+)-4′-(ω-alkanoyloxy)alkoxybiphenyl-4-yl 4-(1-methylheptyloxy)benzoates (nHmR) with highly tilted smectic C* (Sm C*) phase have been synthesised. Phase transition temperatures, enthalpies, tilt angles, spontaneous polarisation, and helical pitches of a few of them have been measured. Most of compounds of nHmR homologous series exhibit Iso-N*-SmC* phase sequence. Compunds of series nHmR exhibit high tilt angles in the SmC* phase (up to 41.5°) and a high value of spontaneous polarisation (near 100 nC/cm²). Their melting points are rather high, above 55°C. Both the melting and the clearing points of all new compounds are decreasing, with the increasing of the total length of the achiral alkyl chain.

Liquid crystal-based sensors offer the advantage of high sensitivity at a low cost. However, they often lack selectivity altogether or require costly and unstable biomaterials to impart this selectivity. To incur this selectivity, we herein integrated a molecularly imprinted polymer (MIP) film recognition unit with a liquid crystal (LC) in an optical cell transducer. We tested the resulting chemosensor for protein determination. We examined two different LCs, each with a different optical birefringence. That way, we revealed the influence of that parameter on the sensitivity of the (human serum albumin)-templated (MIP-HSA) LC chemosensor. The response of this chemosensor with the (MIP-HSA)-recognizing film was linear from 2.2 to 15.2 µM HSA, with a limit of detection of 2.2 µM. These values are sufficient to use the devised chemosensor for HSA determination in biological samples. Importantly, the imprinting factor (IF) of this chemosensor was appreciable, reaching IF = 3.7. This IF value indicated the predominant binding of the HSA through specific rather than nonspecific interactions with the MIP.