Bi-functional NH2-MIL-101(Fe) for one-pot tandem photo-oxidation/Knoevenagel condensation between aromatic alcohols and active methylene compounds

Abstract

Tandem reactions, which enable multistep reactions in one pot, offer enormous economical advantages. For the first time, this manuscript reported that NH₂-MIL-101(Fe), an earth abundant Fe-containing MOF material, can catalyze efficiently the one-pot reaction between aromatic alcohols and active methylene compounds via a tandem photo-oxidation/Knoevenagel condensation under visible light and at room temperature. NH₂-MIL-101(Fe) acts as a photocatalyst for the oxidation of aromatic alcohols to aldehydes as well as a base catalyst for Knoevenagel condensation between the as-formed aldehydes and the active methylene compounds. The comparison of the reactions over NH₂-MIL-101(Fe) and another two MOFs (NH₂-UiO-66(Zr) and NH₂-MIL-125(Ti)) reveals that the strength of the basic sites in the MOFs influences significantly the efficiency of the tandem reaction. This study highlights the great potential of MOFs as multifunctional photocatalysts for one-pot tandem reactions.