Evolution of the Saupe order parameters of enantiomers from a racemic to a non-racemic liquid crystal solvent: an original light on the absolute configuration determination problem

Abstract

Chiral liquid crystals used as solvents have been shown to be very powerful in giving separate nuclear magnetic resonance (NMR) signals for enantiomers. However, a fundamental problem remains: how to attribute absolute configurations to the various NMR responses? In this paper it is demonstrated that the absolute configuration problem could be solved in predicting the sign of the rotation of the principal axis system of the Saupe matrix in the molecular frame when going from an achiral (racemic) to a chiral anisotropic solvent.

Keywords:

• chirality
• absolute configuration
• Saupe order parameters
• NMR
• molecular orientation

Acknowledgments

The authors thank Professors James W. Emsley, Aharon Loewenstein, Edward Samulski and Zeev Luz for their direct or indirect contributions throughout 10 years of work in the field of NMR in chiral liquid crystals.