A Butterfly-like Fluorescent Tracker for Dynamic Polymers

Optically tracking constitutional dynamics provides a time-resolved, non-invasive, and visually interpretable approach to unravel-ing microscopic complexity in system chemistry. Here we report a butterfly-like fluorescent tracker, featuring excited-state conformational adaptivity, capable of sensing the subtle microscopic dynamics of polymers as a ratiometric fluorescent probe. The key design is coupling the fluorophore’s conformational relaxation dynamics to microenvironmental constraints imposed by polymer structural features—such as chain length, conformation, and inter-/intramolecular interactions. By employing the fluorophore as a bifunctional initiator, we grafted two dynamic polymer chains onto its phenyl "wings", creating a single-fluorophore tracker that dynamically interacts with its environment. This system functions as a highly sensitive ratiometric probe, optically reporting microscopic polymer dynamics in real time, including polymerization kinetics, chain folding/unfolding transitions, and depolymerization processes. Systematic studies demonstrate the broad applicability of this concept across diverse polymeric systems, with distinct emission signatures enabling differentiation between systems. The probe’s ability to correlate fluorescence output with microenvironmental changes reveals its utility in both fundamental and applied contexts. We anticipate this conformationally adaptive fluo-rescent platform will advance research in dynamic chemistry, particularly for real-time monitoring of polymeric systems and the development of responsive materials.