Mechanically Planar Chiral [2]Rotaxanes for Multistate Circularly Polarized Luminescence Switching

ABSTRACT Aiming to construct novel solid‐state circularly polarized luminescence (CPL) switches with multistate emission and high dissymmetry factors ( g lum ), a co‐conformationally controllable mechanically planar chiral [2]rotaxane was designed and synthesized. Ascribed to the unique intermolecular three‐dimensional (3D) stacking, the resultant mechanically planar chiral [2]rotaxane exhibits strong CPL in the solid state with a | g lum | value of 0.003. Interestingly, by precisely controlling the interlocked modes between the axle and macrocycle components using two different stimuli, reversible transformations between multiple aggregation states were successfully achieved, including acid‐triggered CPL quenching and Li + ‐triggered CPL enhancement with a | g lum | value of 0.018. Moreover, the dual‐stimuli‐responsive multistate CPL behavior enabled its application in advanced information encryption, highlighting the potential of the mechanically planar chiral platform. As the first CPL switch based on mechanically planar chirality, this proof‐of‐concept study not only provides new insights into multistate solid‐state CPL but also holds potential for developing novel smart chiral luminescent materials for practical applications.