Synthesis and properties of (−)-menthol-derived chiral liquid crystals by introducing adipoyloxy spacer between mesogenic core and chiral menthyl

ABSTRACT

A homologous series of new chiral liquid crystal compounds, M6BnB (n = 2, 4, 6, 8, 10, 12, 14, 16, 18), with varying length of n-alkoxy chains at one end, was formed by covalently linking a chiral (−)-menthyl with biphenyl-benzoate via adipoyloxy spacer group. A combination of analysis methods such as Fourier transform infrared, ¹H NMR spectra, differential scanning calorimetry, polarised optical microscopy and X-ray diffraction was carried out to systematically investigate their phase structures and phase transition behaviours. The length of the flexible terminal alkoxy group has a profound influence on the clearing points (T_iso) and T_iso decrease with the increase of alkoxy chain (n). In addition, increasing the length of the terminal alkoxy group tends to narrow the temperature range of the N* phase and favour the development of chiral smectic C phase.

Graphical Abstract

KEYWORDS:

• (−)-menthol
• chiral liquid crystal
• chain length
• spacer group

Acknowledgements

This work was supported by Fundamental Research Funds for the Central Universities (N160504001), National Nature Science Foundation of China (31560268), Yunnan Science and Technology Project (2015FB156) and Foundation of Yunnan Education Department (2015Z153).

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by Fundamental Research Funds for the Central Universities (N160504001), National Nature Science Foundation of China (31560268), Yunnan Science and Technology Project (2015FB156) and Foundation of Yunnan Education Department (2015Z153).