Smectic C-to-Nematic Transition in p-n-Heptyloxybenzylidene-p-aminobenzoic Acid

The results on the phase transitions in p-n-heptyloxybenzylidene-p-aminobenzoic acid are reported. The microscopic and X-ray studies show that the compound goes over from smectic C to nematic phase directly. The transition entropies and specific heat are determined using differential scanning calorimetry. The translational order parameter is determined using low angle X-ray intensity measurements. The tilt angle in smectic C phase is found to be 56° and is independent of temperature. The X-ray data also lead to the conclusion that the compound exists as a dimer.