Deuterium NMR Evidences of Slow Dynamics in the Nematic Phase of a Banana-Shaped Liquid Crystal

Experimental evidences of the slow dynamic behaviour of a banana-shaped liquid crystal (LC) detected by means of Deuterium Nuclear Magnetic Resonance (DNMR) in its nematic phase are reported. Deuterium line-shape and line-width trends of DNMR spectra of three selectively deuterium-labelled isotopomers of 4-chloro 1,3-phenylene bis 4-4′-(11-undecenyloxy) benzoyloxy benzoate (ClPbis11BB) are discussed in comparison with those of a deuterated probe dissolved in ClPbis11BB, used as LC solvent. Different dynamic regimes are observed for the central and lateral aromatic rings of the probe. These experimental remarks are discussed in terms of overall and internal molecular motions.

Keywords:

• Banana-shaped liquid crystals
• nematic phase
• dynamics
• deuterium NMR

Acknowledgments

This work was financially supported by the P.R.I.N. 2003 (Italian MIUR). One of the authors (VD) thanks Prof. Nandor Eber (Budapest) and Prof. Bostjan Zalar (Ljubljana) for useful discussions.