The Influence of the Molecular Structure of Compounds on Their Properties and the Occurrence of Chiral Smectic Phases.

Abstract

We have designed new chiral smectic mesogens with the -CH2O group near the chiral center. We synthesized two unique rod-like compounds. We determined the mesomorphic properties of these mesogens and confirmed the phase identification using dielectric spectroscopy. Depending on the length of the oligomethylene spacer (i.e., the number of methylene groups) in the achiral part of the molecules, the studied materials show different phase sequences. Moreover, the temperature ranges of the observed smectic phases are different. It can be seen that as the length of the alkyl chain increases, the liquid crystalline material shows more mesophases. Additionally, its clearing (isotropization) temperature increases. The studied compounds are compared with the structurally similar smectogens previously synthesized. The helical pitch measurements were performed using the selective reflection method. These materials can be useful and effective as chiral components and dopants in smectic mixtures targeted for optoelectronics and photonics.