Theoretical Study of Ordering in Liquid Crystals with the Help of Intermolecular Interaction Energy Calculations Part l-Anisaldehyde Azine

Abstract

The ordering of mesogenic compounds in the liquid phase has been investigated using intermolecular interaction energy calculations taking Anisaldehyde azine (CH₃ – O – C₆H₄ - CH = N – N = CH - C₆H₄ - O - CH₃) as a specific example. The molecular structure has been taken from literature. Computations of atomic net charges and dipole moments have been carried out using CNDO/2 method. The multicentered-multipole expansion method has been employed to evaluate the various interaction energy terms viz. electrostatic, polarisation, dispersion, and repulsion. Distance as well as orientation has been changed with a view toward locating the minimum energy configuration. The large interaction energy value obtained through these calculations has been used to explain the liquid crystalline behaviour of this substance. The minimum energy configuration also supports the theoretical findings about the existence of the nematic phase and a high transition temperature.