Photosensitive chiral self-assembling materials: significant effects of small lateral substituents

Abstract

Novel azobenzene-based photosensitive mesogens with lactate chiral units were synthesized. In order to modify the rate of the thermal Z–E isomerization of these compounds, small lateral substituents were introduced into their core in the proximity of the azo group. The influence of lateral substitution on the kinetics of the Z–E isomerization, mesomorphic behaviour, and UV-Vis absorption spectra was studied. It was found that the position of the substituents in the azobenzene core significantly affects the rate of their thermal isomerization. The stability of Z-isomers of several studied compounds is comparable to that of compounds with complex molecular structures designed for optical data storage. Although lateral substitution influences the breadth/length ratio of the core, liquid-crystalline properties of the studied materials have been preserved.