Long-Lived Emissive Hydrogen-Bonded Macrocycles: Donors Regulating Room-Temperature Phosphorescence and Thermally Activated Delayed Fluorescence

Despite vast applications of macrocycles in supramolecular chemistry, achieving long-lived emissions including room-temperature phosphorescence (RTP) or thermally activated delayed fluorescence (TADF) for potential use still presents a great challenge. This work first reports hydrogen-bonded (H-bonded) macrocycles emitting RTP and TADF by introducing various donors onto the same aramide skeleton containing a rigid acceptor. The formation of charge transfer effectively enhances the photoluminescence efficiency. Aromatic carbonyl groups promote the intersystem crossing. The drastically reduced flexibility of chromophores fixed by the H-bonded macrocyclic framework contributes to suppress the nonradiative decay to stabilize triplet excitons. Therefore, RTP and TADF are acquired by altering donors, and are systematically revealed by comparisons with control compounds and theoretical calculations. Finally, near white-light emission (CIE, 0.30, 0.33) is realized via host-guest interactions.

Automated summary

Despite the wide range of applications of macrocycles in supramolecular chemistry, achieving long-lived emissions such as room-temperature phosphorescence or thermally activated delayed fluorescence remains challenging. In this study, hydrogen-bonded macrocycles were developed, which demonstrate room-temperature phosphorescence and thermally activated delayed fluorescence through the introduction of different donors onto a rigid acceptor containing aramide skeleton. The formation of charge transfer and the presence of aromatic carbonyl groups contribute to the enhanced photoluminescence efficiency and intersystem crossing, respectively. The reduced flexibility of the chromophores in the H-bonded macrocyclic framework suppresses nonradiative decay and stabilizes triplet excitons, resulting in the acquisition of room-temperature phosphorescence and thermally activated delayed fluorescence.