Liquid crystalline derivatives exhibiting smectic phases with ferro and antiferroelectric properties

Abstract

Chiral liquid crystalline molecules can self-assemble and create ferroelectricity (FE) or antiferroelectricity (AF) in tilted lamellar smectic C phases. In previous research, lactic acid has been repeatedly applied as an effective source of chirality. In this contribution, we synthesized several mesogens with the aim to establish the role of chiral chain and reveal its influence on the mesogenic and polar properties. For the first studied mesogen, we utilized a methylbutyl in the chiral chain. In the second molecular structure, an (S)-lactate group was added to prolong the chain terminated with a methylbutyl. In the third homologue, two (S)lactates and methylbutyl form the chiral chain. To establish the optical purity by high-performance liquid chromatography (HPLC) method, additional derivatives were prepared with racemic methylbutyl part. We compared all homologues with respect to the effect of the chiral chain modification. The third derivative with two lactates in the chiral chain reveals AF smectic phase, which is stable and enantiotropic in a broad temperature interval, extended to the room temperature, which could be attractive for applications.