Benzoxazole-terminated liquid crystals with high birefringence and large dielectric anisotropy. Issue 9 (14th July 2020)

• Record Type: Journal Article
• Authors: Hu, Kun; Weng, Qiang; Chen, Ran; Li, Jian; Shi, Dingqian; Chen, Pei; Gao, Aiai; Chen, Xinbing; An, Zhongwei
• Is Part Of: Liquid crystals. Volume 47:Issue 9(2020)
• Page Start: 1274
• Page End: 1280
• Publication Date: 2020-07-14
• Subjects: Benzoxazole-terminated compounds -- dielectric anisotropy -- birefringence -- density functional theory -- liquid crystals; Liquid crystals -- Periodicals; 548.905
• DOI: 10.1080/02678292.2019.1710777
• Languages: English
• ISSNs: 0267-8292

Abstract

ABSTRACT: Six benzoxazole-terminated mesogenic compounds with fluoro substituent at different positions were prepared and their properties investigated. The compounds give a high birefringence (Δ n ~ 0.45) and a large-dielectric anisotropy (Δ ε ~ 26), indicating a possible application in liquid-crystal mixture as a dopant to enhance performance of the host mixture. In accordance with conventional high Δ n liquid crystals containing triple carbon-carbon bonds, lateral fluoro substituents and terminal groups can alter the Δ n and Δ ε of benzoxazole-terminated liquid crystals. Meanwhile, some parameters such as dipole moment, polarisability, dihedral angles are calculated with density functional theory (DFT) methods to relate to the experimental Δ n and Δ ε . It is noted that the introduction of the benzoxazole unit is an effective method to enhance Δ n and Δ ε values of the rodlike molecule, this is ascribed to its π-conjugated benzene-fused heterocycle and large dipole moment. Graphical Abstract: uf0001