In this work, the mesomorphic, electro-optic and dielectric properties have been discussed in the light of molecular structure-property correlations of two chiral multilactate liquid crystalline materials possessing the orthogonal paraelectric Smectic A* phase, tilted ferroelectric Smectic C* phase and the tilted antiferroelectric Smectic C_A* phase, over a substantially broad temperature range. Interestingly, a reasonably rare re-entrant Smectic C* phase (SmC_re*) has also been identified in one of the investigated materials. These materials differ in their linkage groups (keto or ether) and an additional chiral unit in the terminal chain. The phase transition temperatures and transition enthalpies were determined from Polarizing Optical Microscopy and Differential Scanning Calorimetry (DSC) measurements. The compounds exhibit negative dielectric anisotropy (Δε) throughout the mesomorphic range (maximum −18 and −4 in SmA* for both the compounds) and moderately high values of spontaneous polarization (∼153 nC/cm² in SmC_re* phase). The temperature dependence of the response time (τ), bulk viscosity (η) and the activation energies (E_a) throughout the mesomorphic phase have been determined from the spontaneous polarization measurements. To emphasize the structure-property correlations in more detail, dielectric spectroscopy measurement has also been performed to measure the dielectric strength, dielectric loss, frequency dependent permittivities, relaxation time and relaxation frequencies. The clear evidence of the relatively rare SmC_re* phase has also been confirmed from the temperature and frequency dependence of the dielectric permittivity. These results shed important light on the emergence of these materials as a smart alternative for their application in multicomponent mixtures targeted for advanced electro-optic and photonic devices.

Chiral calamitic photoactive materials exhibiting self-assembling behaviour attract substantial interest in the soft matter community due to their high potential for the contactless control of mesomorphic, structural, optical, and dielectric properties via UV/visible light irradiation. To advance the structure-property relationships of this class of smart organic materials, several azobenzene derivatives bearing two electron-withdrawing groups at the 4,4′-positions and chiral derived from lactic acid were designed and characterized. Depending on the molecular structure, these materials preferentially exhibit various chiral liquid crystalline (LC) smectic phases, whereas lateral substitution completely suppresses LC behaviour. The E-Z photoisomerization and thermal Z-E relaxation of these chiral compounds were investigated using high-performance liquid chromatography, and the kinetics of the Z-E relaxation process are discussed. Owing to their slow E/Z switching kinetics, these photoactive materials hold potential for multicomponent mixtures aimed at bistable photonic bandgap tuning, long-term optical data storage, and bistable circularly polarized light modulators.