Several new hockey stick-shaped azo compounds are designed and synthesised with an aim to study the effect of different types of linkages and their direction of linking on the mesomorphic properties in such systems. The new compounds synthesised are characterised by spectroscopic methods. The liquid crystalline properties are investigated using polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) studies. They exhibited a variety of mesophases such as nematic (N), smectic A (SmA), anticlinic smectic C (SmC a ), B 1 , etc. We found that the direction of linkage groups has a major effect on the mesomorphic properties when compared to the effect of different types of linkage groups. We observed a reversible photoswitching phenomenon of these compounds in their solution UV-vis spectra.

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Photochromic liquid crystalline dimers that form smectic nanoclusters in nematic mesophases and are capable of forming organogels have been reported.

In this paper, we report the photoresponsive behavior of hockey stick-shaped mesogens bearing azo wing with different terminal alkoxy chains at one terminal end. Except for the compound E16, which exhibits SmC along with nematic phase, all other mentioned compounds exhibit nematic phase alone. Influence of chain length on the photophysical properties were investigated using UV-Vis spectroscopy. It is observed here that influence of chain length is negligible on thermal back relaxation time. Spectroscopic investigation with variable intensities of UV light studies reveals that reverse cis-trans isomerization process was inversely proportional to the intensity of illuminated light. The present study also reveals that the structure-property relationship plays a dominant role on shape anisotropic structures. A spectroscopic study of the solid sample using guest-host mixture was also carried out and the compilation of results forecast these mesogens as ideal candidates for optical storage devices.