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 Ni-2(3,5-Pydc)(2)(H2O)(8)center dot 2H(2)O(1 center dot H2O) was prepared by solvothermal method from 3,5-pyridinedicarboxylic acid, D-camphoric acid and Ni(NO3)(2)center dot 6H(2)O in dimethylformamide(DMF)/water(volume ratio 2:1). And two gold and silver functionalized 1 center dot 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(A(3)) in 1,4-dioxane. The results 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.