The cone phase of liquid crystals: Triangular lattice of double-tilt cylinders

We predict the existence of a new defect-lattice phase near the nematic-smectic-C(NC) transition. This tilt-analogue of the blue phase is a lattice of double-tilt cylinders which are disclination lines in the smectic layer normal as well as the c-field. We discuss the structure and stability of the cone phase. We suggest that many ‘nematics’ exhibiting short range layering and tilt order may in fact be in the molten cone phase, which is a line liquid.     

Alkyloxy azo-cinnamate ester based thermotropic liquid crystals and their photophysical investigations

Two series of rod shaped Schiff base containing azo-cinnamate thermotropic liquid crystalline compounds were synthesized and characterized. These molecules have four different alkyl spacers (n = 6, 8, 10, and 12) at one end and a dodecyloxy chain at another end (n = 12) which influence their liquid crystalline properties. Liquid crystallinity commence from six methylene spacer onwards in the series exhibiting with Nematic to Smectic-C mesophases. Analytical data confirm the molecular structures of homologues series of compounds. The characteristic texture of liquid crystalline phases obtained using polarizing‐light microscope with a heating stage. The structural transformation of these liquid crystals was confirmed by differential scanning calorimetry. All the compounds exhibited various calamitic mesophases with wide mesomorphic temperature ranges. The relationship between structure and mesomorphic properties was discussed in framework of geometrical configuration of central unit, linking part, and length of alkoxy chains. Photosensitive azobenzene group undergoes photoisomerization under UV light and monitored by UV-Visible spectroscopy.