New negative dielectric anisotropy liquid crystals based on benzofuran core

ABSTRACT

In this paper, new liquid crystal compounds with negative dielectric anisotropy were synthesised by regulating the substituents on the benzofuran ring. Their structures were confirmed by ¹H-nuclear magnetic resonance, ¹³CNMR and mass spectra. The effects of substituent on the properties of liquid crystals were investigated. Compared with the reference compounds, the compounds with 5-ethoxy-6,7-difluorobenzofuran ring exhibit higher clearing points as well as the tendency of expansion of SmA phase range. The density functional theory calculation results reveal that the 6-ethoxy-7-fluorobenzofuran-based compound has smaller aspect ratio than that of the 5-ethoxy-6,7-difluorobenzofuran-based compound, which results in the diminish of the mesophase. Although the dielectric anisotropy of the 5-ethoxy-6,7-difluorobenzofuran-based compound is slightly lower than that of the reference compound, it has both the largest perpendicular and parallel dielectric constant.

Graphical abstract

KEYWORDS:

• Liquid crystal
• negative dielectric anisotropy
• benzofuran
• synthesis
• property

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is supported by the Key Research and Development Program of Shaanxi [Program No. 2019ZDLGY04-06].