A dye-loaded Fe4L4 cage for efficient photocatalytic C(sp3)-H activation.

We report the rational construction of a novel cationic metal-organic cage C1 featuring a well-defined Fe4L4 tetrahedral structure. C1 possesses a large inner cavity and robust openings, which enable it to act as an ideal supramolecular host to encapsulate the anionic photosensitizer anthraquinone-2,6-disulfonic acid disodium salt (AQDS) via host-guest interactions to form a photoactive host-guest complex. Benefiting from the spatial confinement effect of the cage cavity, AQDS and reaction substrates are colocalized in the confined microenvironment, converting the diffusion controlled intermolecular reaction into a highly efficient pseudo-intramolecular process. This supramolecular photocatalytic system achieves efficient oxidation of C(sp3)-H bonds under mild conditions, without relying on the high temperature and pressure protocols required by traditional synthetic methods, providing a valuable confinement strategy for the design of high performance photocatalytic systems.