On the Structure—Property Correlations of a New Class of Chiral Liquid Crystalline Materials: A Perspective from Electro-Optic and Dielectric Measurements

The results of electro-optic and dielectric measurements have been discussed in the light of molecular structure–property correlations on two chiral liquid crystalline materials possessing paraelectric SmA*, ferroelectric SmC* and antiferroelectric SmCA* phases, which 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 precisely determined from Polarising Optical Microscopy (POM) and Modulated Differential Scanning Calorimetry (MDSC) measurements. The compounds exhibit negative dielectric anisotropy, (Δε) of around −6 and −1 in the SmC* phase and a moderately high spontaneous polarization of around 80–130 nC/cm2. The temperature dependence of the response time, τ, bulk viscosity, η and the activation energies in the SmC* phase have been determined, from which interesting structure property correlations have been elucidated specially in terms of the molecular geometry arising due to the presence of an additional chiral unit in the terminal chain. These results shed important light on the emergence of these materials as a smart alternative for their application in electro optic and photonic devices.