https://doi.org/10.65770/NXQE8406
ABSTRACT
A novel homologous series of thermotropic liquid crystalline azo-esters, (2-(4’-n-alkoxy-3’-methoxybenzoyloxy)-naphthylazo-2’’-methoxybenzenes) (C₁-C₁₈), has been synthesized via a three step pathway involving Williamson ether synthesis, diazotization, and Steglich esterification. Comprehensive characterization using ¹H NMR, FTIR, mass spectrometry, and elemental analysis confirmed molecular structures. Mesomorphic properties were systematically investigated using polarized optical microscopy and differential scanning calorimetry. Compounds C₇-C₁₈ exhibit well defined liquid crystalline behavior, with C₇-C₁₂ displaying dual nematic-smectic polymorphism. Nematic clearing temperatures range from 159-177°C, while smectic transitions occur at 126-152°C, with mesophase ranges spanning 17-51°C. The synergistic effects of naphthalene cores (enhanced π-π stacking), azo linkages (molecular rigidity), ester connections (thermal stability), and methoxy lateral substituents (dipolar interactions) contribute to the robust mesomorphic behavior. This study establishes fundamental structure property relationships for multi ring azo ester mesogens and provides molecular design principles for advanced liquid crystalline materials with applications in display technologies and photonic devices.
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