Gold and Silver Nanoparticles Supported on Metal-organic Frameworks： a Highly Active Catalyst for Three-component Coupling Reaction

Engineering metal-organic frameworks（MOF） for heterogeneous catalysts have been of extreme interest since they have large pore size within the crystalline framework and well defined pore architecture. Ni-containing MOF Ni2（3,5-Pydc）2（H2O）8·2H2O（1·H2O） was prepared by solvothermal method from 3,5-pyridinedicarboxylic acid, D-camphoric acid and Ni（NO3）2·6H2O in dimethylformamide（DMF）/water（volume ratio 2：1）. And two gold and silver functionalized 1·H2O catalysts were prepared by impregnation method. Catalysts 2.53%Au/MOF and 4.23%Ag/MOF were in-depth characterized by single crystal X-ray diffraction, powder X-ray diffraction（PXRD）, thermogravimetric analysis（TGA）, transmission electron microscopy（TEM）, and inductively coupled plasma-atomic emission spectroscopy（ICP-AES）. Their catalytic performance was examined in one-pot synthesis of structurally divergent propargylamines via three component coupling of aldehyde, alkyne, and amine（A3） in 1,4-dioxane. The resuits show that the catalysts all displayed high reactivities, and a selectivity of 100% for propargylamines. Catalysts 2.53%Au/MOF and 4.23%Ag/MOF have proved to be applicable to a wide range of substrates. Catalysts 2.53%Au/MOF and 4.23%Ag/MOF can be easily recycled and used repetitively at least 3 times with a slight drop in activity. These features render the catalysts particularly attractive in the practice of propargylamines synthesis in an environmentally friendly manner.