Host-guest directed construction of phenothiazine supramolecular frameworks with enhanced oxygen reactivity for visible-light photocatalysis

Abstract

Supramolecular organic frameworks (SOFs) have emerged as promising photocatalytic materials due to their structural tunability and dynamic self-assembly, yet their construction often suffers from limited building block diversity and insufficient reactive oxygen species (ROS) regulation. Herein, we report a novel phenothiazine-based SOF (PTZ-SOF) constructed via cucurbit[8]uril-mediated host-guest self-assembly, affording two-dimensional nanosheets with periodic porous structures in the aqueous solution. This design overcomes conventional SOF limitations by integrating electron-rich phenothiazine units with strong host-guest interactions, enabling efficient electron transfer. The PTZ-SOF exhibited synergistic singlet oxygen (1O2) and superoxide anion radicals (O2•–) generation, significantly outperforming the monomeric 3PPTZ in ROS yield. Leveraging this dual ROS pathway, the PTZ-SOF can be used as efficient photocatalysts to catalyze the condensation-cyclization of ortho-aminobenzenethiols with aldehydes under visible light, achieving up to 93% yield in H2O without metal catalysts. The system demonstrated broad substrate compatibility, operational simplicity, and green reaction conditions. This work provides a new paradigm for SOF construction through host-guest engineering and establishes phenothiazine frameworks as efficient, metal-free photocatalysts for organic transformations.