Hydrophobic MIL-101@PDMS composite confined Frustrated Lewis pairs: Excellent water-tolerance emerged in the hydrogenation of carbonyl compounds

Abstract

Frustrated Lewis pairs (FLPs) have demonstrated remarkable efficacy in metal-free hydrogenation, yet necessitate rigorous anhydrous reaction conditions. To address this concern, we propose a novel approach to enhance the water resistance of FLP by establishing a hydrophobic microenvironment. The inclusion of B(C6F5)3 within a MIL-101 framework, enveloped by hydrophobic polydimethylsiloxane (PDMS) coating, facilitates the in-situ formation of FLP in a solvent of 1,4-dioxane. The hydrophobic PDMS effectively prevents the ingress of water into the MOF nanocages, while simultaneously enabling the diffusion of 1,4-dioxane into the MOF nanocages for FLP formation. Consequently, the as-prepared FLP/MIL-101@PDMS composite exhibits superior water tolerance in the hydrogenation of benzaldehyde and can be utilized directly in commercially available solvents without necessitating stringent inert conditions. Remarkably, FLP/MIL-101@PDMS showcases unparalleled water tolerance even in the presence of 15 equivalents of water relative to B(C6F5)3. This research introduces innovative concepts for designing water-tolerant FLP.