The measurement of weak chirality using nematic liquid crystals

ABSTRACT

Two recently reported methods for measuring weak chirality using nematic liquid crystals are described. These are between one and two orders of magnitude more sensitive than the standard Grandjean-Cano wedge. Pitch lengths of 50 mm have been measured with prospects for extending this beyond 100 mm; this is equivalent to measuring the presence of 1 ppm of a strong chiral dopant. Results for a number of standard chiral dopants and nematic liquid crystal hosts are reported.

GRAPHICAL ABSTRACT

KEYWORDS:

• Chiral liquid crystals
• measurement of weak chirality
• long pitch lengths
• enantiomeric excess

Acknowledgements

We would like to acknowledge numerous stimulating and helpful interactions with John Goodby and Stephen Cowling. We have had numerous helpful discussions with both, but particularly with John. These discussions were instrumental in one of us (EPR) developing an interest in the measurement of weak chirality using nematic liquid crystals, and resulted in enjoyable and productive sabbatical terms and post retirement time being spent in John’s group in York. They also resulted in one of us (XJ) being recruited to study for a PhD in John’s group; we are both grateful for the generous hospitality shown. We are delighted to dedicate this article to the Festschrift in John’s honour on the occasion of his 65th birthday.

Disclosure statement

No potential conflict of interest was reported by the authors.