Synthesis And Properties Study Of Bent-core Liquid Crystals And Unsymmetric Bent-core Azobenzen Monomers

Central groups or side chains have a great effect on the properties of liquid crystals. In this paper, a compound with 4-substituted resorcinol as the central unit was synthesized, and its liquid crystalline behavior was studied by DSC combining with the POM observation.The azo (-N=N-) linkage has particular thermochemistry and actinochemistry behavior, the azobenzene group can undergo reversible cis-trans isomerization under light irradiation and its nonlinear optical properties possess the potential applications in the aspects of molecular design, photofixation, photochromics, thermochromism etc, in this paper, several azo unsymmetric liquid crystalline molecues with 4-amino-3-methylbenzoic acid or 4-amino-3-fluorobenzoic acid as bent core Schiff base or ester group as linkage were synthesized. Their chemical structures were confirmed by 1H NMR and HRMS spectra. The UV-Vis absorbance of these compounds and nine azo bent-core compounds were studied. The angle of the bent-core molecules was simulated. The trans-form of azo compounds showed a strong band in the UV region (330-370nm) and a weak band at 440-450nm. It was found that a close relationship exist between the angle of the molecules and the UV-Vis absorption.