Aggregation-Enhanced Photocleavage for Time-Resolved Multicolor Fluorescence Encryption and Quaternary Optical...

Dynamic fluorescence systems capable of generating time-resolved multicolor optical outputs are highly desirable for advanced information encryption and optical storage. However, precise regulation of fluorescence evolution kinetics remains challenging, as most reported systems either exhibit intrinsically fixed photochemical kinetics or require complex multicomponent assemblies. Herein, we report an aggregation-regulated photochemical system in which the photocleavage kinetics can be continuously programmed through aggregation-dependent excited-state engineering. A donor-acceptor luminogen, TPEMN, with a photocleavable central vinyl bridge was rationally designed. Upon photoirradiation, TPEMN undergoes a pronounced aggregation-enhanced photooxidative cleavage process in which photoreaction kinetics accelerate progressively with aggregation degree, accompanied by continuous multiple fluorescence evolutions from orange to blue. Systematic experimental and theoretical investigations reveal that aggregation suppresses excited-state structural relaxation, prolongs excited-state lifetime, facilitates intersystem crossing, and promotes reactive oxygen species generation, thereby markedly leading to accelerated photocleavage kinetics. This converts conventional binary photoresponses into well-resolved time-dependent fluorescence states, allowing demonstration of time-gated information encryption with deceptive intermediates, multilevel anti-counterfeiting with "burn-after-read" functionality, and high-density quaternary optical storage. This work establishes aggregation-regulated excited-state engineering as a novel paradigm for manipulating photochemical reactivity, providing a conceptual framework for the development of high-efficiency photoreactions, adaptive stimulus-responsive materials, and dynamic information applications.