Pre‑Embedded Intramolecular Donor–Acceptor Engineering in Isoreticular Covalent Organic Frameworks for Efficient Photocatalytic Hydrogen Evolution

Modulating intrinsic molecular dipoles via donor–acceptor ( D – A ) skeleton engineering is an effective strategy for promoting charge dynamics in organic photocatalysts. However, conventional intermolecular D – A covalent organic frameworks (COFs) suffer from weak electronic coupling and uncontrollable dipole strength, with elusive structure–dipole–activity relationships. Herein, two isoreticular imine‐linked COFs are fabricated via pre‐embedded intramolecular D – A engineering. Unlike conventional intermolecular D – A COFs assembled from independent donor and acceptor monomers, the donor and acceptor units are covalently locked within a single C 3 ‐symmetric building block. Periodic integration of the pre‐embedded intramolecular D – A motif endows CR‐COF‐7 with improved crystalline ordering, accessible porosity, and enhanced framework polarization. Periodic calculations reveal an electrostatic potential step of 0.220 eV across the CR‐COF‐7 layer and a 0.76 eV reduction in work function, favoring electron transfer to platinum (Pt). Complementary spectroscopic and photoelectrochemical measurements support the notion of facilitated exciton conversion and enhanced utilization of photogenerated charges. Consequently, CR‐COF‐7 exhibits a photocatalytic hydrogen evolution rate of 12.09 mmol g −1 h −1 , approximately 150‐fold higher than that of CR‐COF‐8, and outperforms an intermolecular D – A COF control. This work reveals the dipole regulation mechanism of intramolecular D – A modification and provides a general design principle for high‐efficiency COF‐based solar photocatalysts.