Fluorescence Self‐Reporting of Molecular Diffusion in Two‐Component Systems via Cocrystallization‐Driven AIE Assembly

Abstract Molecular motion plays a pivotal role in regulating the properties and functions of materials. While significant advancements have been made in elucidating molecular dynamics in single‐component systems, understanding molecular diffusion and motion between distinct components remains challenging. In this work, a cocrystallization‐driven aggregation‐induced emission (AIE) assembly strategy is reported that enables the in situ and real‐time visualization of spontaneous and directional molecular diffusion through the coassembly of dibenzo‐heterocyclic donor and electron‐deficient acceptor molecules. Using fluorescence as a self‐reporting signal, this strategy allows for direct monitoring of the molecular diffusion within two‐component systems. Furthermore, by exploiting the AIE characteristics and rapid fluorescence response, a water‐jet rewritable encryption paper is developed that permits high‐resolution patterning using water as ink, with the printed content erasable by heating, thereby offering excellent reversibility and durability. This study not only offers new insights into the dynamics of molecular diffusion during the cocrystallization process, but also provides a promising approach for the design of functional multicomponent aggregate systems with advanced applications.