2C09 Photoinduced switching of cholesteric liquid crystal networks : Effect of structure of chiral azobenzene molecules

Abstract

Several chiral azobenzene compounds, which have different chiral substituents, were prepared. Mixing each azobenzene compound in host nematic liquid crystal induced a cholesteric phase. We measured the twisting power of the chiral azobenzene compounds before and after ultraviolet irradiation to cause trans-cis photoisomerization of the chiral azobenzene compounds. The twisting power was dependent on the trans-cis photoisomerization. Most of the compounds were found to show decrease in the twisting power by ultraviolet irradiation. On the other hand, the twisting power of (L, L) -Azo-6, which has chiral groups at both end of the Azo group, was increased. The effect of the phase structures of cholesteric liquid crystals will be discussed.