Two-Color Cholesteric Liquid Crystalline Gels for Reversible Writing and Erasing Information Encryption.

Bright structural color derived from the unique helical superstructure of cholesteric liquid crystals (CLCs) has attracted much attention. In addition, fluorescence color is an intrinsic emission upon excitation, which can be observed often under UV light. However, it is a challenge to combine the fluorescence and structural colors to construct a self-supporting system at the same time. In this work, a photoresponsive cyanostilbene-based gelator (CSpy-C10) is synthesized, which emits blue fluorescence in LC. CSpy-C10 can gel LCs and further construct thermo-/photoresponsive CLC physical gels. The structural color of the CLCs, fluorescence, and mechanical properties of the gels can be independently regulated due to the separation of the chiral unit and photoresponsive unit with aggregation-induced emission behavior. Finally, the reversible information encryption including writing and erasing based on the changes in fluorescence are explored. This kind of two-color material can be applied in the fields ranging from information encryption, fluorescent display to high-tech anticounterfeiting.