Photochemical afterglow of single organic molecules with wide‐range tunable lifetime

Abstract Background Photochemical afterglow that relies on slow release of photons from the chemical energy stored by light pre‐irradiation has emerged as a new optical imaging modality. However, conventional photochemical afterglow systems are considerably dependent on the interaction between multiple functional molecules, such as the afterglow initiator, the substrate, and the emitter. Therefore, these isolated functional molecules for afterglow luminescence have to be embedded in a nanoparticle with a confined space for many applications, which may suffer from problems like reproducibility and dye leakage. Aim Herein, we developed an “All‐in‐one” strategy that integrated all functional units for afterglow luminescence into one molecule to achieve photochemical afterglow of single organic small molecules. Material & Methods Triphenylamine and its derivatives contained single organic molecule were synthesized as “All‐in‐one” molecules, and underwent photochemical reactions triggered by singlet oxygen. We investigated the effect of substituents on the afterglow luminescence of the “All‐in‐one” molecules. Experimental measurements and theoretical calculations were performed to exhibit the wide‐range tunable lifetimes and to reveal the involving mechanisms. Results By tailoring the electron‐withdrawing ability of substituents, the afterglow lifetime of the “All‐in‐one” molecules can be conveniently tuned in a wide range from 28.6 s to 50.9 min. Moreover, the “All‐in‐one” afterglow materials were used to make smart printable security inks for optical multiplexing. Discussion & Conclusion Such “All‐in‐one” afterglow molecules successfully achieved bright afterglow with wide‐range tunable lifetimes by the regulation of molecular structure according to the effect of substituents. This work provided a novel strategy to convert traditional fluorescent dyes into afterglow materials of single organic molecules and showed its great potential in multiple information encryption and advanced biological.