Generation, Capture, Storage and Release of Singlet Oxygen from A Perylene Diimide‐Based Metallacage for Oxygen Sensing

The controlled generation and utilization of singlet oxygen (1O2) are crucial for its diverse applications but remain challenging due to its high reactivity and short‐lived nature. Here, we report a box‐shaped metallacage prepared via multicomponent coordination‐driven self‐assembly using tetrapyridyl perylene diimide (PDI) and tetracarboxylate anthracene as building blocks. Upon photo‐irradiation, the PDI faces act as photosensitizers to generate 1O2, which reacts with the anthracene pillars to form a peroxidized metallacage, where 1O2 is captured and stored as anthracene peroxides. Heating releases 1O2 quantitatively, restoring the original metallacage structure. Both states are stable at room temperature, as confirmed by X‐ray diffraction. Additionally, photoinduced electron transfer (PET) from anthracene pillars to PDI faces quenches the emission of the metallacage, while oxidation of anthracene inhibits PET, yielding bright fluorescence for the peroxidized metallacage. This reversible emission change enables the metallacage to function as a “turn‐on” fluorescence sensor for dissolved oxygen, with a detection limit of 1.1×10‐3 mg/L. This study demonstrates a metallacage that can generate, capture, store, and release 1O2 for oxygen sensing, offering insights for designing stimuli‐responsive smart materials.