Liquid Crystals Containing the Isoxazole and Tetrazole Heterocycles

ABSTRACT The influence of the bridging group between the mesogenic group and the terminal position on liquid-crystalline behavior was investigated. Two liquid-crystalline series containing pentagonal heterocycles were synthesized for this purpose. The liquid-crystal phase of mesogens with the isoxazole group was more stable than that of those with isoxazole and tetrazole groups in the same molecule. The mesogens with only the isoxazole group showed better thermal properties than those with isoxazoles and tetrazoles. Nematic and smectic phases were observed. The mesophase sequences of the materials were investigated by polarization microscopy and DSC (Differential Scanning Calorimetry).