The Molecular Structure and Orientation of Phenoxathiin in a Nematic Liquid Crystal Determined from NMR Spectroscopyt

Abstract

'H-NMR spectra of a tricyclic compound phenoxathiin have been analyzed in a nematic liquid crystal ZLI 1167 and the chemical structure and molecular orientation determined. A damping subroutine was incorporated into the modified LAOCN 3 program to improve the worse convergency encountered when corrections calculated for the variable parameters were large. The order and the structural parameters have been derived from the direct couplings and compared with those reported for the related tricyclic compounds. The dihedral angle between the two benzene rings was about 18° wider than that determined in a crystal state. This tendency resembles to the case of thianthrene. The order parameters supported that the long axis of phenoxathiin orients parallel to that of the liquid crystal. Comparison of the order parameters of some tricyclic compounds suggested that they are dependent on the molecular structure when measured in a same liquid crystal solvent.