Synthesis, characterization and mesomorphic properties of some azo-schiff base liquid crystalline compounds

الملخص EN

Five azo Schiff base liquid crystalline compounds with different polar groups named (D1S, D2S, D3S, D4S, D5S)have been synthesized and their structures were characterized using FTIR spectrometry technique , while their liquid crystalline phase transition and temperature range was confirmed by differential scanning calometery which indicate the presence of liquid crystalline phases with a relatively different temperature ranges.

The textures of the synthesized liquid crystalline compounds were performed using polarized optical microscope which show a clear nematic phases with a thread and droplets like nature with a wide temperature range between (23.52 - 43.23 º C) with the exception of the two compounds (D2S, D3S) which shows a smectic phase of few temperatures ranging between ( 12.5 - 14.71 º C) in addition to the nematic phase stated above .

For the purpose of geometry optimization of structures of chemical compounds prepared in this research we have been use of the computer program known (Alchemy 2000 version 1), in which the optimization for the studied structures of liquid crystalline compounds confirmed the required linearity for mesophase formation , we then obtained values of the electric dipole of these compounds, which has been found to be in the range (0.7565 - 3.7547 Deby )