Abstract

A supramolecular hydrogen-bonded thermotropic liquid-crystalline complex was synthesized by combining myristic acid (MC) and 4-n-pentyloxybenzoic acid (5BAO) in an equimolar ratio, and its mesogenic, optical, and thermal characteristics were systematically investigated. The formation of intermolecular hydrogen bonding between the carboxylic acid groups of the precursor molecules was confirmed by Fourier transform infrared spectroscopy, which revealed characteristic shifts in the O-H and C=O stretching vibrations after complexation. The mesomorphic behaviour of the prepared complex was examined by polarizing optical microscopy, which identified the presence of nematic and smectic C mesophases through their characteristic optical textures during the cooling cycle. Differential scanning calorimetry further established the corresponding phase-transition temperatures and enthalpy changes in both heating and cooling runs. The complex exhibited phase transitions associated with crystal, smectic C, nematic, and isotropic states, demonstrating rich phase polymorphism and good thermal response. Thermal analysis also indicated that the nematic phase possessed a wider mesophase range and greater thermal stability than the smectic C phase. In addition, specific heat and transition-order analyses supported the thermal behaviour of the system. The observed spectral response suggests that the complex may serve as a promising candidate for tunable optical filtering and thermally responsive liquid-crystalline applications.

Keywords

Linear Supramolecular Hydrogen Bonded Liquid Crystals, Phase Variance, Phase Polymorphism, Transition Temperatures, Thermal Parameters,

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