Preparation of Magnetically Recyclable MIL-101-immobilized Frustrated Lewis Pairs for the Reduction of Aldehydes and Ketones

Frustrated Lewis pairs (FLPs), composed of spatially hindered Lewis acids and bases, are promising catalysts for the catalytic hydrogenation of unsaturated organic substrates, but the lack of reusability limits their development. The functionalization of solid materials with molecular FLP is a promising method for preparing heterogeneous FLP catalysts. In this work, a magnetically recyclable FLP catalyst was successfully prepared for the reductive carbonyl compounds to the corresponding alcohols. FLP of 2-Ph2PPhCHO/B(C6F5)3 was grafted into NH2-MIL-101@Fe3O4 composite material through an aldehyde-amine condensation reaction. The as-prepared FLP-NH-MIL-101@Fe3O4 exhibited remarkable catalytic activity for aldehyde/ketone carbonyl compounds. In addition, FLP-NH-MIL-101@Fe3O4 displays outstanding magnetic recyclability and can be reused 8 times without loss of activity. The magnetic heterogeneous catalyst FLP-NH-MIL-101@Fe3O4, prepared by immobilizing FLP onto magnetic MOF, shows outstanding catalytic activity and recyclability for the reduction of aldehyde/ketone carbonyl compounds. The design strategy opens up a new direction for the research of heterogeneous FLP catalysts. image