Azo-linked room temperature columnar liquid crystals with bisphenol A core: Structure property relationship and photophysical properties

A series of bent-shaped liquid crystals containing an azo group and a bisphenol A core were synthesized, and characterized using various techniques. The presence of mesogenic properties in these azo-based dimers was confirmed through POM, DSC, and high-temperature XRD analysis. The structure-property relationship is further studied to confirmed the effect of the variable alkyl side chain on the terminal position, which also affects the liquid crystalline properties of the compounds in terms of mesophase temperature range and thermal stability. All the compounds exhibited enantiotropy columnar hexagonal phase with wide temperature range and thermal stability. Their photophysical properties were investigated using UV–visible spectroscopy and spectrofluorometry. It was observed that all four columnar mesogens underwent cis and trans azo isomerization upon exposure to photoisomerization.