A New Chirality Invertible Photoswitch: Light-Driven Axially Chiral Hydrazone Enabling Dynamic Handedness Inversion of Self- Organized Helical Superstructure

Inspired by nature, dynamic self-organized helical superstructures are becoming attractive as building blocks in soft photonic crystals and advanced chiroptical devices. Herein, a chirality invertible hydrazone photoswitch, possessing high helical twisting power (HTP) was judiciously designed and synthesized. Due to the photoinduced configuration changes of the hydrazone photoswitch, it displayed superior thermal stability and strikingly reversible HTP changes. By incorporating a novel chiral hydra zone (CH) into the liquid crystal (LC) host, a handedness invertible cholesteric liquid crystal (CLC) helical superstructure with high thermal stability and light-modulated photonic bandgap was prepared. We inferred that the mechanism of chirality inversion of the novel CH photo switch derived from changes in the dihedral angle between the two naphthalene rings induced by hydrazone isomerization. Therefore, the influence of chemical structures on its photoresponsiveness was explored. Finally, the potential applications of this advanced light-driven CLC in soft photonic crystals, showing erasable and rewritable colorful patterns and chiroptical templates to induce handedness invertible circularly polarized luminescence were illustrated.