Novel benzoxazole-based liquid crystals with negative dielectric anisotropy and moderate optical anisotropy

ABSTRACTA series of new liquid crystal compounds with negative dielectric anisotropy was synthesised by regulating the orientation of the substituents on the benzoxazole ring, namely, 5–4-(2-(4-(alkoxy)phenyl)-2,3-difluorophenyl)benzo[d]oxazole derivatives (nPP(2,3)FO). These compounds mainly display enantiotropic nematic mesophases in the ranges of 8.62–16.09°C (heating process) and 23.98–30.32°C (cooling process), moderate birefringence (Δn) ranging from 0.25–0.32 (DFT theoretical calculation) and 0.22–0.28 (experimental measurement), as well as negative dielectric anisotropy (Δɛ) ranging from −2.77 to −2.94. These characterises are ascribed to the larger perpendicular dipole moments and orientation angles of benzoxazole. This work provides new ideas for the rational design of negative dielectric anisotropy liquid crystals.KEYWORDS: Heterocyclic liquid crystalsnegative dielectric anisotropybezoxazoledensity functional theory AcknowledgmentsThe authors thank for the financial support by National Nature Science Foundation of China (51773112, 51873100 and 62105194), Sanqin scholars innovation teams in Shaanxi Province, China, Program for Science & Technology Innovation Team of Shaanxi Province, China (2018TD-030), and International Science and Technology Cooperation Project of Shaanxi Province, China (2021KW-20).Disclosure statementNo potential conflict of interest was reported by the author(s).Supplementary materialSupplemental data for this article can be accessed online at https://doi.org/10.1080/02678292.2023.2259843.Additional informationFundingThe work was supported by the Sanqin scholars innovation teams in Shaanxi Province, China, and International Science and Technology Cooperation Project of Shaanxi Province, China [2021 KW-20]; National Science Foundation Committee of China [51773112]; Program for Science & Technology Innovation Team of Shaanxi Province, China [2018TD-030].