Molecular Crystals and Liquid Crystals, Vol.641, 10-24, 2016
Structural and thermo-optic studies on linear double hydrogen bonded ferroelectric liquid crystal homologous series
A novel series of supramolecular hydrogen bonded ferroelectric liquid crystal (HBFLC) is formed through hydrogen bonding interaction between nonmesogenic dextro-levo tartaric acid (DLTA) and mesogenic p-n-alkyloxy benzoic acids (nBAO, where n = 7 to 12). The formation of hydrogen bond in the complex is confirmed through Fourier transform infrared spectroscopy (FTIR) studies. Optical and thermal behaviors for mesomorphic phases of individual complex in the series are meticulously studied by means of differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Computation of the enthalpy values in the homologous series of complex during both heating and cooling cycles is proved that thermal equilibrium exhibited by the complex system. Extended thermal span width and rich liquid crystallinity is observed in the present complex due to the presence of aromatic ring with chiral center. Thermal stability factor and thermal equilibrium are also discussed. Presence of alkyloxy chain on either side of chiral molecules hinder the abundant reduction in phase transition temperature and lowered melting point compared to the individual mesogens. Optical tilt angle for smectic C* phase is determined and the same is fitted to a power law.