Electron Transfer Mediator-Enabled Modular Control of ¹O₂ and O₂ ^•- Generation in Porphyrin Supramolecular Frameworks...

The inherent preference of classical type II photosensitizers for generating singlet oxygen (¹O₂) via energy transfer presents a key challenge in developing type I systems capable of producing superoxide radicals (O₂ ^•-) through electron transfer. Herein, we report a porphyrin-based supramolecular organic framework (SOF, TPP-BPY-CB[8]) assembled via host-guest interactions with cucurbit[8]uril (CB[8]), which achieves a significantly enhanced ¹O₂ quantum yield (94.04%) compared to the monomeric unit TPP-BPY (74.52%). To overcome the energy transfer-dominated reactive oxygen species (ROS) pathway, a series of electron transfer mediators were introduced to modulate the excited-state dynamics, resulting in BQ@TPP-BPY-CB[8] that effectively switches the ROS pathway from type II to type I. This mediator-driven modulation not only enables O₂ ^•- production under hypoxic conditions but also expands the functional diversity of the SOF system. The two ROS pathways are selectively leveraged in photocatalytic applications: TPP-BPY-CB[8] excels in ¹O₂-mediated oxidation of organophosphorus compounds, while BQ@TPP-BPY-CB[8] facilitates highly efficient thiol-ene cross-coupling via O₂ ^•- promotion. This work presents a robust strategy for tailoring ROS generation in supramolecular photocatalysis, offering a new design paradigm for multifunctional, ROS-directed photoreactive materials.