Supramolecular Photoinduced Electron Transfer between a Redox‐Active Hexanuclear Metal–Organic Cylinder and an Encapsulated Ruthenium(II) Complex

By using redox‐active nickel(II) ions as the connect nodes, a hexanuclear metal–organic cylinder (Ni‐YL) was achieved through self‐assembly with a large cavity and an opening windows capable to accommodate guest molecules. The suitable cavity of Ni‐YL provides an opportunity to encapsulate the anionic ruthenium bipyridine derivative Ru(dcbpy)₃] (dcbpy=2,2′‐bipyridine‐4,4′‐dicarboxylic acid) as the photosensitizer for light‐driven reactions. The host–guest behavior between Ni‐YL and Ru(dcbpy)₃] was investigated by mass spectrometry, NMR spectroscopy, and computational studies, revealing an effective binding of the guest Ru(dcbpy)₃] within the cavity of Ni‐YL. Optical experiments suggested a pseudo‐intramolecular photoinduced electron transfer (PET) process between the Ru(dcbpy)₃] and the host Ni‐YL, leading to an efficient light‐driven hydrogen production based on this system. Control experiments with a mononuclear Ni complex as a reference photocatalyst and the inactive Fe(dcbpy)₃] as an inhibitor for comparison were also performed to confirm such a supramolecular photocatalysis process.