The Nematic Phases of Bent-Core Liquid Crystals

• Published in: Chemphyschem Vol. 15; no. 7; pp. 1251 - 1260
• Main Authors: Gleeson, Helen F., Kaur, Sarabjot, Görtz, Verena, Belaissaoui, Abdel, Cowling, Stephen, Goodby, John W.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 19.05.2014; WILEY‐VCH Verlag; Wiley; Wiley Subscription Services, Inc
• Subjects: bent-core molecules; Condensed matter: structure, mechanical and thermal properties; Dielectric properties; Exact sciences and technology; Liquid crystals; Minireviews; Molecular structure; nematic phases; oxadiazoles; Physical properties; Physics; Structure of solids and liquids; crystallography; Superconductors; Temperature; nematic phases; Oxadiazoles; Nematic state; bent-core motecules; Liquid crystals; Physical properties; liquid crystal; oxadiazoles; physical properties; bent-core molecules; liquid crystals
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201400014

Over the last ten years, the nematic phases of liquid crystals formed from bent‐core structures have provoked considerable research because of their remarkable properties. This Minireview summarises some recent measurements of the physical properties of these systems, as well as describing some new data. We concentrate on oxadiazole‐based materials as exemplars of this class of nematogens, but also describe some other bent‐core systems. The influence of molecular structure on the stability of the nematic phase is described, together with progress in reducing the nematic transition temperatures by modifications to the molecular structure. The physical properties of bent‐core nematic materials have proven difficult to study, but patterns are emerging regarding their optical and dielectric properties. Recent breakthroughs in understanding the elastic and flexoelectric behaviour are summarised. Finally, some exemplars of unusual electric field behaviour are described. Bent on stability: The nematic liquid‐crystal phases formed by bent‐core molecules have remarkable properties. This Minireview reports recent progress in stabilizing the nematic phase at accessible temperatures, concentrating on oxadiazole‐based materials. It also describes recent measurements of their physical properties, including optical, dielectric, elastic, and flexoelectric coefficients, and electric field effects (see graphic).