Liquid Crystalline Behaviours of the Complexes Based on 1,3,4-Oxadiazole Derivative and Benzoic Acid

A non-liquid crystal compound (4-POXD-6) containing the 1,3,4-oxadiazole group and pyridyl (py) group was synthesized. And a series of supramolecular mesogenic complexes were obtained by mixing 4-POXD-6 and 4-alkoxybenzoic acids (Cn, n=6, 8, 12). The liquid crystalline properties of 4-POXD-6/Cn (n=6, 8, 12) were investigated by means of differential scanning calorimetry, polarized optical microscopy, and wide-angle X-ray diffraction. It was found that 4-POXD-6/Cn (6, 8) display monotropic nematic and smectic A phases, while 4-POXD-6/C12 exhibits a SmX phase in the heating process and a SmA phase in the cooling run. Variable-temperature FTIR spectroscopic studies revealed hydrogen bonds existed in both crystalline and liquid crystalline phases.