Conformation‐Engineered B←N Macrocycles: A New Paradigm for Metal‐Free Photocatalytic H ₂ O ₂ Production

Comprehensive Summary Supramolecular macrocycles, despite their ubiquity in molecular recognition, have remained largely unexplored in photocatalysis due to their intrinsic lack of continuous π‐conjugation and inefficient charge‐carrier separation. Here, we report a conformational engineering strategy to integrate dynamic B←N dative bonds into highly active photocatalytic macrocyclic architectures. By simply switching the boronate linker from meta to para geometry, we control the rotational freedom of B←N bonds to yield two isomeric frameworks‐twisted BNF‐80 and planar BNF‐81‐with well‐defined supramolecular macrocyclic building units, as unequivocally confirmed by single‐crystal X‐ray diffraction. The planarized conformation of BNF‐81 enforces extended π‐conjugation and continuous π‐π stacking, leading to markedly enhanced charge separation efficiency and charge transfer. As a result, BNF‐81 achieves an outstanding photocatalytic H 2 O 2 production rate of 4275 μmol·g –1 ·h –1 under visible light in pure water without any sacrificial agent, outperforming previously reported B←N‐based photocatalysts. This work establishes linker conformation driven control as a powerful design principle, unlocking the latent photocatalytic potential of supramolecular macrocycles and opening a new avenue for developing efficient metal‐free photocatalysts.