Hydrogen Bonding Regulated Microenvironments in Covalent Organic Frameworks for Photocatalytic H ₂ O ₂ Generation and C–H Annulation

Hydrogen bonding, as a subtle yet powerful noncovalent interaction, plays a critical role in steering proton-coupled electron transfer (PCET) processes; however, its influence within photocatalytic covalent organic frameworks (COFs) has remained underexplored. Here, we present a molecular-level regulation of isoreticular COFs incorporating pyridine- and pyrimidine-based linkers in which the positional arrangement of nitrogen atoms is deliberately modulated to construct distinct hydrogen-bonding microenvironments. As a result, Tp-4,6-Pm exhibits a 7-fold enhancement in H2O2 generation rate compared to Tp-2,6-Pd, achieving a notable solar-to-chemical conversion (SCC) efficiency of 1.48%. Mechanistic studies reveal that hydrogen bonding networks facilitate the generation of surface-bound hydrogen (Had) and stabilize the *OOH intermediate, thereby lowering the energetic barriers for H2O2 photosynthesis. Furthermore, the optimized microenvironment promotes efficient superoxide (•O2–) formation, enabling α-amino C–H annulation with high reactivity. This hydrogen-bonding-regulated microenvironment strategy provides a generalizable approach for activating PCET processes in COFs, offering a powerful design principle for next-generation photocatalytic systems.