Single-layer 2D supramolecular-organic-framework-supported polyoxometalates: efficient selective oxidation of toluene in seawater under sunlight†

Abstract

Performing organic reactions in water, particularly in seawater under sunlight, is a desirable objective in chemistry because both are the most abundant and cheapest resources on the Earth. Herein, we describe a simple and useful hierarchical assembly based on host–guest interactions that yields tunable macrocycle (cucurbit[10]uril, Q[10])-based hybrid single-layer 2D supramolecular-organic-framework nanosheets (POM@Q[10]-SOFs) in water. The resulting 2D hybrid assemblies as heterojunction photocatalysts offer multiple electron transfer pathways for the generation of chlorine radicals (˙Cl) in aqueous solution, thereby facilitating highly selective photooxidation of the inert C(sp³)–H bonds of toluene to benzaldehyde at room temperature, even in seawater under sunlight. Notably, control experiments revealed that Q[10]-SOFs play a pivotal role in the photocatalytic process, which can be attributed to the viologen in Q[10]-SOFs acting as an electron acceptor and transfer station, effectively promoting the separation of electron–hole pairs within the integrated 2D hybrid assemblies. This work demonstrated the rational application of seawater in organic reactions.