Glycomacrocycle-Based Azobenzene Derivatives as Chiral Dopants for Photoresponsive Cholesteric Liquid Crystals

We demonstrate photoresponsive cholesteric liquid crystals (CLCs) doped with glycomacrocyclic azobenzene derivatives, which exhibit large conformational changes, providing dynamic control of helical superstructures in response to a light stimulus. An unprecedented shortening of the helical pitch length and the empowerment of helical twisting power up to 500% are observed upon trans (E) to cis (Z) photoisomerization. Light-driven dynamic helix twisting and untwisting behavior affords the first example of glycomacrocyclic azobenzene-based CLCs, which can drive the mechanical movement of micro-objects. Two modes of rotation—two-directional or one-directional rotational motion (crankshaft mode)—are realized. In particular, the latter mode based on the reversible cholesteric texture transition between homogeneous stripes and focal conics leads to the accumulation of the rotation angles achieving the amplified mechanical movements.