Mortise-and-Tenon-Joint-Type Assembled Stable Porphyrin-Based Hydrogen-Bonded Organic Frameworks for Photooxidation

Abstract Porphyrin-based hydrogen-bonded organic frameworks (HOFs) are promising crystalline porous materials that integrate structural stability with photoactivity. Herein, three isostructural porphyrinic HOFs (PFC-168, PFC-168-Cu, and PFC-168-Ni) are constructed through a hierarchical mortise-and-tenon-type interlocked assembly. Unlike conventional layered or π-stacked porphyrinic HOFs, the PFC-168 series features cuboidal secondary building blocks that interconnect through complementary geometric interlocking. Among them, metal-free PFC-168 exhibits good thermal and solvent stability as well as superior hydrolytic stability. Structural analysis combined with density functional theory calculations reveals that, although metallization strengthens interlayer interactions, the denser framework-supporting hydrogen-bonding network in PFC-168 provides a larger cumulative stabilization contribution. This result highlights that HOF stability is governed by the cooperative balance of hydrogen bonding, geometric interlocking, and other weak interactions. Moreover, PFC-168 integrates photoactive porphyrin units into the periodic porous structure, enabling efficient singlet oxygen generation and making it a robust heterogeneous photocatalyst for the visible-light-driven oxidation of 1,5-dihydroxynaphthalene. This work establishes a structure–stability–function relationship in porphyrin-based HOFs and provides mechanistic guidance for designing robust photoactive HOFs.