Orthogonal Supramolecular Assembly Triggered by Inclusion and Exclusion Interactions with Cucurbit[7]uril for Photocatalytic H2 Evolution.

The fabrication of efficient and convenient photocatalytic H2 evolution systems is a fascinating research topic in the field of solar energy conversion. A ternary self-assembled photocatalytic H2 evolution system was fabricated through supramolecular host-guest chemistry. The system consisted of the H2 evolution catalyst [Co(dmgH)2 (4-ppy)2 ]NO3 (1; dmgH2 =dimethylglyoxime, 4-ppy=4-phenylpyridine) and the photosensitizer Eosin Y (EY) assembled with the macrocyclic compound cucurbit[7]uril (CB[7]) to form the 1@CB[7]/EY complex through inclusion and exclusion interactions, respectively. The synchronous self-assembly drives an orthogonal arrangement of the 1@CB[7]/EY system. The inclusion complex 1@CB[7] was successfully characterized by 1 H NMR spectroscopy and single-crystal XRD. The exclusion process of CB[7] with EY was identified by NMR titration and the optimized geometry of the exclusion structure was determined by DFT calculations. The use of CB[7] resulted in a 6-fold increase in turnover number, a 3-fold increase in turnover frequency, and a 3-fold extension of lifetime for photocatalytic H2 evolution as compared with the system in the absence of CB[7]. The improvement of the light-driven H2 evolution activity was ascribed to the ability of CB[7] to link the photosensitizer and catalyst.