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

Graphical Get in or get out : A cobaloxime catalyst and Eosin Y photosensitizer were assembled with macrocyclic cucurbit[7]uril through inclusion and exclusion interactions, respectively. The synchronous self-assembly drove an orthogonal arrangement of the ternary system with significant spatial proximity. The ternary supramolecular system showed better performance for photocatalytic H 2 evolution than multicomponent systems. The fabrication of efficient and convenient photocatalytic H 2 evolution systems is a fascinating research topic in the field of solar energy conversion. A ternary self-assembled photocatalytic H 2 evolution system was fabricated through supramolecular host–guest chemistry. The system consisted of the H 2 evolution catalyst [Co(dmgH) 2 (4-ppy) 2 ]NO 3 ( 1 ; dmgH 2 =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 H 2 evolution as compared with the system in the absence of CB[7]. The improvement of the light-driven H 2 evolution activity was ascribed to the ability of CB[7] to link the photosensitizer and catalyst.