Electron Transfer Mediator–Enabled Modular Control of 1 O 2 and O 2 •– Generation in Porphyrin Supramolecular Frameworks for Selective Photosynthesis

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-CB8) assembled via host-guest interactions with cucurbit8uril (CB8), 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-CB8 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-CB8 excels in 1O2-mediated oxidation of organophosphorus compounds, while BQ@TPP-BPY-CB8 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.