“Near magic angle” sample spinning in NMR spectra of molecules oriented in individual and mixed liquid crystals of opposite diamagnetic anisotropies

https://doi.org/10.1016/0009-2614(87)80446-3Get rights and content

Abstract

The dynamics of the liquid crystal director in “near magic angle” sample spinning has been investigated in mesophases with positive and negative diamagnetic susceptibility anisotropies and their mixtures with near-zero macroscopic diamagnetic anisotropy. To this end the deuteron quadrupolar splitting of deuterochloroform dissolved in liquid crystals has been monitored. In systems with weakly positive diamagnetic susceptibility anisotropy (Δχ), the director has been observed to switch from an orientation parallel to the spinning axis at low rotational speeds to one perpendicular to the spinning axis at high rotational speeds when the angle (θ) the axis of rotation makes with the magnetic field is smaller than the magic angle (θm). For systems with a small negative Δχ similar director behaviour has been observed for θ greater than θm.

References (12)

  • T. Vaananen et al.

    Chem. Phys. Letters

    (1986)
  • C.L. Khetrapal et al.

    Chem. Phys. Letters

    (1981)
  • J.W. Emsley et al.
  • C.L. Khetrapal et al.
  • J. Courtieu et al.

    J. Chem. Phys.

    (1983)
  • R. Teeaar et al.

    Org. Magn. Reson.

    (1982)
There are more references available in the full text version of this article.

Cited by (12)

  • Advances in NMR Studies of Liquid Crystals

    2004, Annual Reports on NMR Spectroscopy
    Citation Excerpt :

    These dipolar coupling constants are important for the study of conformational equilibria of flexible chain(s) in LC. Long range 2H13C dipolar coupling constants have been obtained from 1D 13C spectra of monodeuterated LC.69,245,246 For example, the proton-decoupled 13C NMR spectrum of a monodeuterated 4′-(1-deuteropentyloxy)-4-biphenylcarbonitrile (5OCB-d1) gives nine 2H13C dipolar coupling constants for carbon ranging from one to six bonds from the deuterium nucleus.247

  • Variable angle sample spinning NMR in liquid crystals

    1994, Progress in Nuclear Magnetic Resonance Spectroscopy
View all citing articles on Scopus
1

To whom correspondence should be addressed.

View full text