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

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.