Nuclear magnetic resonance studies of molecular structure, reorientation and order matrix of some substituted benzaldehydes partially oriented in a nematic liquid crystal

Abstract

Molecular structure and order parameters are obtained in this study from nuclear magnetic resonance spectra of p-fluoro, p-chloro, p-bromo and p-nitrobenzaldehyde partially oriented in EBBA. Reorientation is found to be correlated with rotation of the —CHO group. The angle between the principal order axis and the effective C ₂ axis is linearly dependent on the molecular length, indicating that the shape of the molecule is the major factor determining the orientation of these molecules in the nematic phase.