A new series of azobenezene liquid crystals (LCs) was designed and synthesised by known and straightforward methods. The central connecting cores of the molecules varied viz., benzene/naphthalene/biphenyl. The molecular structures were confirmed by infrared, UV, nuclear magnetic resonance spectroscopic techniques. The LC texture and thermal phase behaviours were investigated by polarising optical microscopy and differential scanning calorimetry. Smectic B phase was found in biphenyl-derived azobenzene ester. The effect of central core on LC properties was investigated. The decreased angle at central connecting core suppressed the melting points, phase transition temperatures without losing LC properties, whereas, in moderate angle compounds LC properties were suppressed. The compounds with increased angle at central core favours rich mesomorphism.

In this work, we are presenting synthesis, characterization and their mesomorphic properties of some new calamatic shaped liquid crystal molecules with chiral centre. The chiral centre was fixed at one end of the molecule and other end was modified by various alkyl substituents. Most of the molecules showing wide range of smectic A, nematic and ferroelectric SmC* mesophases enantiotropically. Chemical structures were established by IR, NMR and their mesophase behaviours by DSC, POM and X-ray instrumentations.

Three sets of new rod-shaped liquid crystals with one terminal fixed branched alkyl chain, other terminal with varying normal alkyl chain, and central naphthalene with terminal branched chain derived symmetric molecules were synthesized and characterized. Chemical structures were confirmed by standard analytical methods. Liquid crystal properties were evaluated with the help of differential scanning calorimetry, polarized optical microscopy and X-ray studies. All the compounds favoured to exhibit highly birefringent smectic and nematic mesophase textures. Further, symmetric naphthalene derivatives preferably exhibited nematic mesophase with elevated transition temperatures.

The cyano/nitrile group-derived calamitic molecules are synthesized and characterized for the search of pure nematic phase. The chemical structures were confirmed using standard spectroscopic techniques such as IR, NMR, and elemental analysis. Mesophases were analyzed and characterized by the combination of POM, DSC, and X-ray analysis methods. Most of the compounds show nematic mesophases with moderate transition ranges. Further detailed studies may leads to special nematics like uniaxial/biaxial nematic, twist-bent nematic and cybotactic nematic mesophases.