Study the effect of different terminal substituents on the liquid crystalline properties of the new synthesized 1,2,4-oxadiazole derivatives

A new series of 4-(5-(p-tolyl)-1,2,4-oxadiazol-3-yl)phenyl substitutedbenzoate, (IIIx) incorporating ester linkage with various substituted groups in various positions on the phenyl ring were synthesized and investigated by FT-IR and H-1-NMR spectroscopies in addition to the CHN analysis, their mesophase behaviors were examined by optical polarized microscopy (OPM) and differential scanning calorimetry (DSC). Only the derivatives that have terminal substituents in the para position showed liquid crystalline properties with a wide range of nematic phase and various textures (Schlieren, thread-like, marble and nematic droplets) both in heating and/or cooling runs. The relationship between nature and position of the substituent groups, central core and ester linkage of these derivatives with their liquid crystalline properties were studied and the results were analyzed, discussed and compared with other mesogenic materials have a chemical composition similar to the compounds prepared in this study. [GRAPHICS] .