NMR studies of molecules oriented in mixed thermotropic liquid crystals of opposite diamagnetic anisotropies

Abstract

NMR spectra of molecules oriented in a mixture of thermotropic liquid crystals of opposite diamagnetic anisotropies show novel features and provide useful information. At a critical concentration and temperature, it is observed that two discrete solute orientations corresponding to those in the two types of liquid crystals coexist. The scope and the limitations of the experiments in the determination of the chemical shift anisotropy without the use of a reference or the change of experimental conditions and the individual values of the direct and the indirect couplings between heteronuclei are examined and the results are discussed.