Aggregation-Induced Emission From Fluorophore-Quencher Dyads With Long-Lived Luminescence

Aggregation-induced emission (ATE) is an important photophysical phenomenon in molecular materials and has found broad applications in optoelectronics, bioimaging, and chemosensing. Currently, the majority of reported ALE-active molecules are based on either propeller-shaped rotamers or donor acceptor molecules with strong intramolecular charge-transfer states. Here, we report a new design motif, where a fluorophore is covalently tethered to a quencher, to expand the scope of ATE-active materials. The fluorophore quencher dyad (FQD) is nonemissive in solutions due to photoinduced electron-transfer quenching but becomes luminescent in the solid state. The intrinsic emission lifetimes are found to be within the microseconds domain at both room and low temperatures. We performed single-crystal X-ray diffraction measurement for each of the FQDs as well as theoretical calculations to account for the possible origin of the long-lived ATE. These FQDs represent a new class of ATE-active molecules with potential applications in organic optoelectronics.