A nanosized confined space with well-defined functional surfaces has great potential to control the efficiency and selectivity of catalytic reactions. Herein we report that a 1,6-diene, which normally forms an intramolecular [2+2] cycloadduct under photoirradiation, preferentially undergoes a photoinduced olefin migration in a porous crystal, metal− macrocycle framework (MMF), and alternatively [2+2] cycloaddition is completely inhibited in the confined space. A plausible reaction mechanism for olefin migration triggered by the photoinduced dissociation of the Pd−Cl bond is suggested based on UV−vis diffuse reflectance spectroscopy, singlecrystal XRD, and MS-CASPT2 calculation. The substrate scope of the photoinduced olefin migration in MMF was also examined using substituted allylbenzene derivatives.

Non-covalent immobilisation of catalysts in nanoporous materials is a promising way to apply homogeneous catalysts to heterogeneous catalytic reactions. Herein we report a size-specific catalytic reaction with an acid catalyst, p-toluenesulfonic acid, immobilised in a porous molecular crystal, metal-macrocycle framework (MMF), composed of metallo-macrocycles. A tritylated substrate which is smaller than the pore dimension of MMF was deprotected by the heterogeneous catalyst, whereas the reaction with a larger substrate was completely suppressed due to the steric restriction.

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Porous crystals with well-defined active metal centers on the pore surface have high potential as heterogeneous metal catalysts. We have recently demonstrated that a porous molecular crystal, metal-macrocycle framework (MMF), catalyzes olefin migration reactions by photoactivation of its Pd II Cl 2 moieties exposed on the crystalline channel surface. Herein we report a mechanistic study of the photo-induced olefin migration reactions at the Pd II active centers of MMF. Several experiments, including a deuterium scrambling study, revealed that olefin migration is catalyzed via an alkyl mechanism by in situ generated PdÀ H species on the channel surface during photoirradiation. This proposed mechanism was further supported by DFT and ONIOM calculations.