Integrated Singlet Oxygen Generation, Capture, Storage, and Release in a Single Conjugated Scaffold

Singlet oxygen (¹O₂) is a highly reactive species central to applications ranging from materials science to photodynamic therapy, yet its detection and controlled handling remain challenging. Herein, we report two new 4a,5a-dihydroazuleno[2,1,8-ija]azulene derivatives, T-AA-F and K-AA-F, uniquely integrate photosensitization, ¹O₂ capture, storage, and release within a single small-molecule scaffold. Upon UV or visible light irradiation, both compounds generate ¹O₂ and undergo a selective [4 + 2] cycloaddition at the fused furan unit to form stable endoperoxides exhibiting red emission. Prolonged irradiation using UV (365 nm) or visible light (525 nm) triggers a ring-opening reaction, regenerates the ketone derivatives while releasing ¹O₂, as confirmed by EPR spectroscopy using TEMP as a trapping agent. The endoperoxides display high thermal stability up to 90 °C, enabling robust ¹O₂ storage. This fully integrated molecular system represents a rare example of a single-component platform capable of producing, trapping, storing, and releasing ¹O₂, offering promising opportunities for sensing and bioimaging applications.