Exploring the behaviour of the twist-bend nematic phase using NMR with a variety of spin probes

ABSTRACT

Here we discuss the use of deuteriated probe molecules in NMR studies of the nematic (N) and twist-bend nematic (N_TB) phases formed by the generic liquid crystal dimer CB7CB. The key properties of three probes dissolved in the N_TB phase investigated are the orientational order S_zz^B and the conical angle, θ₀, of the director with respect to the spectrometer field. In addition for one probe 5CB-d₂ it is possible to obtain a measure of the phase chirality from the difference in the quadrupolar splittings given by the prochiral pair of deuterons. The relative simplicity of the probes facilitates the determination of the key properties which are obtained using two different approaches.

GRAPHICAL ABSTRACT

KEYWORDS:

• Conical angle
• phase chirality
• prochiral deuterons
• Haller function
• Surface Interaction model

Acknowledgments

We are most grateful to Dr. Sebastian Fabritz of the Max-Planck-Institut für Medizinische Forschung who provided us with invaluable assistance in the purification of 1CB-d₃.

Disclosure statement

No potential conflict of interest was reported by the authors.