Synthesis and characterization of liquid crystalline behaviour of new materials incorporating two heterocyclic 1, 3, 4-oxadiazole and 1, 3, 4-thiadiazole rings

الملخص EN

The synthesis and mesomorphic properties of 5-(4-methoxyphenyl)-2-[2-(4'-nalkoxy)- 1,3,4-thiadiazole-5-methylenethio]-1,3,4-oxadiazole (series [VI]n), were described for the number of the carbon atoms in alkoxy chains varying from 1-8.

In addition, four compounds containing 4'-chloro [VI]a, 4'-nitro [VI]b, 4'-methoxate [VIII]1 and 4'-heptoxate [VIII]7 instead of 4'-alkoxy group were also synthesized to study the effect of terminal substituent.

All compounds have been characterized by elemental analysis, and FTIR, mass 1HNMR spectrometry.

The liquid crystalline properties were investigated by differential scanning calorimetry (DSC) and optical polarized microscopy (OPM).

The homologous with n=2-4 show enantiotropicnematicmesophase.

The higher homologous (n = 5-8) and compound with 4'-heptaloxate [VIII]7 substituent show enantiotropicnematic and smectic phases.

Finally, the three compounds 4'-chloro [VI]a, 4'-nitro [VI]b, and 4'-metoxate [VIII]1 did not show any mesomorphic properties.