The synthesis and investigation of mesomorphic, dielectric, and electro-optic behavior of novel chiral imine-based rod-like liquid crystal

Abstract

The synthesis and mesomorphic properties of novel chiral imine-based rod-like molecules carrying a (S)-3,7-Dimethyloctyloxy unit and a n-decyloxy chain at terminals have been reported. Novel molecules, (S)-5-n-decyloxy-2-[[[4 '-(3,7-dimethyloctyloxy)phenyl]imino]methyl]phenol (5) and (S)-4-n-decyloxybenzylidene-4 '-(3,7-dimethyloctyloxy)aniline (6), differ from each other by the presence of a lateral hydroxy group on aryl aldehyde. The both structures have been identified by H-1-NMR, C-13-NMR, FT-IR spectroscopy, and MS-QTOF. The mesomorphism of molecules have been investigated by optical polarizing microscopy as well as differential scanning calorimetry. The presence of a lateral hydroxy group leads to a notable mesophase stability up to 37 degrees C in the chiral tilted smectic (SmC*) mesophase interval as compared to imine analog 6 due to intramolecular hydrogen bonding. Therefore, the investigation of dielectric and impedance parameters as well as electro-optic behavior of chiral rod-like compound 5 derived from salicylaldimine-core have been carried out. The real and imaginary dielectric constant, conductivity mechanism, impedance, and dielectric relaxation mechanism of new chiral compound 5, exhibiting an enantiotropic SmC* mesophase which shows a ferroelectric switching with P-S values in the range of 220-100 nC cm(-2), have been investigated in the frequency range between 100 rad/s and 10(6) rad/s at different temperatures altering from 25 to 85 degrees C.