Thermal, Optical, and Dielectric Analysis of Hydrogen-Bonded Liquid Crystals Formed by Adipic and Alkyloxy Benzoic Acids

Intermolecular hydrogen-bonded homologous series comprising of eight liquid crystalline complexes are isolated and characterized. Double complimentary hydrogen bonds are formed between non-mesogen adipic acid (AA) and mesogenic p-n-alkyloxy benzoic acid (nBAO), the series is referred to as AA+nBAO. Hydrogen bond formation is evinced through Fourier transform infrared spectroscopy (FTIR) studies, while the mesogenic phases are identified by polarizing optical microscopic (POM) studies, which are further confirmed by differential scanning calorimetry (DSC). Phase diagram is constructed from the data of DSC and POM studies. The variation of tilt angle with temperature in smectic C phase is fitted to a power law and the exponent value (beta) is found to be in agreement with Mean Field predicted value.