Catalytic Properties of Amine-Grafted Metal-Organic Framework MIL-101

In porous hybrid materials, the existence of coordinatively unsaturated metal sites (CUS) is very beneficial since these sites can strongly interact with guest molecules such as gases and organic molecules in adsorption and catalysis. The CUS in MIL-101, the chromium(III) terephthalate with zeotypic giant pores, can be selectively functionalized, in a way differing from the functionalization of mesoporous silica and porous hybrids reported so far. This work reports catalytic activities in MOF, grafted with ethylene diamine (ED) and diethylene triamine (DETA) on the CUS Cr(III) of MIL-101. They exhibit remarkably high activities in the Knoevenagel condensation compared to that of the mesophase. ED-grafted MIL-101, a size-selective molecular sieve catalyst, is also able to encapsulate noble metals (Pd, Pt, and Au). In particular, the Pd-loaded MIL-101 catalyses the Heck coupling reaction, with a high activity comparable with that of a commercial Pd/C catalyst.