Topological engineering of covalent organic frameworks enhances photoactivation of electron donor–acceptor complexes via conformational locking

Electron donor-acceptor (EDA) complex photoactivation offers a valuable route for organic synthesis, yet the development of efficient catalytic systems remains a significant challenge. We present a novel strategy based on topological conformational locking within covalent organic frameworks (COFs) to engineer high-performance donor platforms. Specifically, we constructed a three-dimensional (3D) COF and two two-dimensional (2D) analogues from the conformationally flexible building block 4,4',4″,4″'-(1,4-phenylenebis(azanetriyl))tetrabenzaldehyde (PATB). Unlike the 2D structures, the 3D architecture intrinsically restricts molecular flexibility, stabilizing a locked conformation that significantly enhances acceptor binding affinity and facilitates efficient EDA complex formation and electron transfer. The 3D-PATB COF exhibits superior photocatalytic activity across a range of transformations, including C-H functionalization and [3+2] cyclization, and supports gram-scale synthesis with outstanding structural stability. Both experimental and computational analyses underscore the critical role of conformational locking in boosting catalytic performance, establishing topological engineering as a powerful approach for advancing EDA complex photochemistry.