Unveiling the Inversion-Symmetry-Driven Excitation Switching in Aggregation-Induced Emission

Understanding the aggregation-induced emission (AIE) mechanism, where the fluorescence is enhanced upon aggregation, is a critical step in predictably designing AIE molecules for use in novel applications. Here, we report a π–π stacked AIE chromophore, A3MN, that demonstrates the switching of the excitation maximum when moving from monomers to aggregates, which has never been reported before. Also, we elucidate such switching by revealing a novel electronic origin for AIE via inversion-symmetry-driven fluorescence in A3MN. We observe this unique fluorescence phenomenon being affected by mechanical crushing and the rate of dissolution of crystals in the solvent. This inversion-symmetry-driven emission phenomenon plays a pivotal role in modulating the AIE of A3MN aggregates in solution, films, and crystals. The insights unveiled here allow the design and engineering of AIE systems that can be adopted in a multitude of applications including mechanical impact/damage memory storage (and reading) using luminescence, quantum computing, sensing, and super-resolution imaging.