Conjugation Interruption in 1D COFs for Boosted Charge Separation and Photocatalytic 2,3‐Dihydrobenzofuran Synthesis

ABSTRACT Covalent organic frameworks (COFs) are appealing photocatalyst platforms because of their structural designability and tunable optoelectronic properties. However, the traditional strategy of extending π‐conjugation to improve light absorption often increases exciton binding energy and suppresses charge separation, creating a trade‐off that limits catalytic performance. Here, we introduce a conjugation‐interruption strategy for the first time to construct efficient COF‐based photocatalysts, where methylene (sp 3 ) bridges are incorporated into one‐dimensional (1D) framework backbones to moderately disrupt long‐range conjugation, localize electrons and reduce exciton binding energy. Schiff base condensation of the 4‐connected thiadiazole‐containing tetra‐aldehyde with 2‐connected angular diamine precursors consisting of naphthyl, phenyl, and methylene bridges afforded BT‐NDA‐COF, BT‐TDA‐COF, and BT‐MDA‐COF, respectively. BT‐MDA‐COF with the weakest conjugation, exhibits the longest fluorescence lifetime (1.57 ns) and the lowest exciton binding energy (63.21 meV), clearly outperforming its fully conjugated counterparts (BT‐TDA‐COF and BT‐NDA‐COF). Combined experimental and theoretical analyses reveal that the methylene bridges induce structural distortion and weaken exciton confinement, thereby promoting charge separation. This superior charge separation enables gram‐scale photocatalytic synthesis of bioactive 2,3‐dihydrobenzofurans with 98% yield, demonstrating the practical potential of conjugation interruption in COFs for green, high‐efficiency photocatalytic organic synthesis.