Heterocyclic Liquid Crystal Materials

In this work synthesis and characterization of a novel series of compounds, polymers containing 1,3,4-thiadiazole and 1,2,4-triazole units are described. All of these materials in this study are characterized by FTIR, 1HNMR, 13CNMR, Mass and UV spectroscopy. The liquid crystalline properties of the prepared compounds were verified using differential scanning calorimeter (DSC) and hot-stage optical polarizing microscopy (OPM). The first series of this study containing two 1,3,4-thiadiazole Schiff bases rings connected with two terminal alkoxyphenyl rings. These compounds exhibited eneantiotripic nematic and smectic phases while other compounds did not exist any liquid crystalline behaviours. To comparison the liquid crystalline behaviour of these compounds, the two series having the azoxy groups instead of azomethine groups was synthesized. The difference between the azomethine compounds with that of azoxy group, The latter compounds did not show any liquid crystalline properties. Polyesters and polyethers were also prepared and found that all polymers did not show liquid crystalline properties but simply go to the glass transition temperatures Tg and then to isotropic melt.