Orientation Studies by NMR on Polycyclic Aromatic Molecules Dissolved in Nematic Liquid Crystals

Abstract

The degrees of order of 7 solute polycyclic aromatic ring systems have been measured on the basis of ²H-NMR spectra in the liquid crystal solvents EBBA and ZLI 1132. Bond contributions to the interaction energy of the solute molecules with the solvents have been determined. They are found to be transferable so that orientations of molecules can be predicted as long as there is no contradiction between the symmetry of a molecule based on the number and direction of bonds and the symmetry based on the position of bonds or molecular shape as e.g. in perylene.

Key Words:

• NMR
• order of polycyclic aromatic ring systems
• bond contributions to orientation energy
• transferability of bond contributions