Synthesis, Characterization, and Liquid Crystalline Behavior of Ester-Schiff Base Derivatives Attached to Nonyl and Tetradecyl Terminal Chains

In this study, a series of ester and Schiff base derivatives, (E)-4-((4-n)benzylidene)amino) phenyl-4-nitrobenzoate, was successfully synthesized and characterized.These derivatives consist of nonyl and tetradecyl groups at the end of their chains.The research was done with three reaction schemes: alkylation, condensation, and esterification.All the synthesized compounds were characterized using Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and CHN elemental analysis.Observation under POM showed that the final compounds with nonyl and tetradecyl terminal chains exhibited a smectic A (SmA) phase in both cycles.These results were further verified by differential scanning calorimetry (DSC) to confirm the mesophase's transition temperature.The structure-property relationship investigations showed the mesogenic compounds to exhibit liquid crystal properties due to the linearity of the molecules, which maintain the rigidity of the core system.In addition, a high number of electronegativity atoms attached resulted in the compound having a high polarizability that induced the liquid crystal behavior.