Polar smectic phases in quasi-bent-core liquid crystals with hockey-stick-shaped mesogen: synthesis and crossover mesomorphism

ABSTRACT

New hockey-stick-shaped liquid crystals (HSLCs) have been designed and synthesised. By extreme shortening of one ‘arm’ in the HSLCs, we have constructed the pronounced overall hockey-stick-shaped molecular conformation of these materials, and called the pseudo-rod-like (PRL) molecules with hockey-stick-shaped mesogen. The chemical structures were identified using spectroscopy and elemental analysis. The mesomorphic behaviour was investigated by polarising optical microscopy (POM), differential scanning calorimetry (DSC), X-ray diffractometry (XRD), and via electro-optical experiments. As a result, in spite of the PRL molecules, the various mesomorphic polymorphism, the interdigitated bi-layered structure and macroscopic polarity were found. Similar to up-to-date HSLCs, the quasi-bent-core LCs showed a transition from the synclinic SmC phase (SmC_s) to anticlinic SmC (SmC_a) phase, and exhibited SmA-type (N_CybA) and SmC-type (N_CybC) cybotactic nematic phases. At the same time, similar to practical rod-like LCs, the PRL molecules showed good surface alignment behaviour under planar boundary conditions.

Graphical Abstract

KEYWORDS:

• Polar symmetry
• hockey-stick liquid crystals
• mesophase polymorphism
• interdigitated bilayer structure
• uniform texture

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary materials

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Additional information

Funding

This research was supported by the Basic Science Research Program (No. NRF-2017R1D1A1B03030179) through the National Research Foundation of Korea (NRF) grants funded by the Korea government (MSIP).