Switching Monomer‐to‐Excimer Fluorescence by Noncovalent Interaction Competition Strategy.

Noncovalent fluorescence switching materials with specific molecular packing motifs for desired performance are difficult to design accurately due to the complexity of intermolecular interactions. Herein, a noncovalent interaction competition strategy to design fluorescence‐switching materials by fine‐modulating hydrogen‐bond and π–π interactions is proposed. Hydrogen bonds are generated by nitrogen/oxygen‐containing units while π–π interactions are generated between polycyclic aromatic hydrocarbons. After these two interactions are balanced in strength, they attempt to induce the formation of respective molecule assemblies stably under controllable conditions. Through thermal stimulus produced by a laser, a reversible assembly transition with high‐contrast monomer‐to‐excimer fluorescence switching is achieved, which demonstrates promising applications in rewritable optical recording and time‐dependent anti‐counterfeiting. This strategy provides a crucial step toward the controllable switching of supramolecular assembly for information handling. [ABSTRACT FROM AUTHOR]