Inside Front Cover: Band‐Gap Engineering of Isoreticular Hydrogen‐Bonded Organic Frameworks for Boosting Photocatalytic Hydrogen Evolution (Angew. Chem. Int. Ed. 19/2026)

Rational band-gap engineering in hydrogen-bonded organic frameworks (HOFs) remains challenging. Based on HOF-102, π extended donor–acceptor building units were designed to construct isoreticular HOFs with tunable band gaps (2.46–1.86 eV). The optimized HOF-1022(CN) exhibits enhanced charge transfer and suppressed recombination, achieving a hydrogen evolution rate of 168.2 mmol g−1 h−1 (8.5 fold increase) and an AQY of 7.3% at 420 nm. This first band-gap engineering of HOFs establishes a general design strategy for high performance photocatalysts, as reported in the Research Article (e25987) by Hongyu Chen, Peng Li, and co-workers.