Synthesis, characterization and photophysical study of cholesterol functionalized azo-based room temperature liquid crystals

Four new liquid crystalline materials (HA1-HA4) with cholesteryl group and azo-ester linking group interconnected with two-side substituted flexible alkoxy side chains were deliberated and synthesized. The structure confirmation of the azo mesogens was investigated by using FT-IR, 1H NMR, and 13C NMR techniques. The phase behavior of the materials was investigated by crossed polarizing optical microscopy (POM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) techniques. All four targeted materials shows smectic type mesogenic properties and further stabilized up to room temperature to lower temperature. The structure-property relationship of present azo-based materials was discussed to investigate the scope of mesogenic properties. All four materials (HA1-HA4) display wide temperature range mesophase as 52.5 degrees C, 54.7 degrees C, 52.7 degrees C, and 54.1 degrees C. The photoresponsive properties of the azo-based bi-substituted materials were well examined by UV study.