Metal-Organic Frameworks as Selective or Chiral Oxidation Catalysts

Abstract

Since the discovery of Metal Organic Frameworks (MOFs) in the early 1990, the amount of new structures has grown exponentially. A MOF typically consists of inorganic nodes that are connected by organic linkers to form crystalline, highly porous structures. MOFs have attracted a lot of attention lately, as the versatile design of such materials holds promises of interesting applications in various fields. In this review, we will focus on the use of MOFs as heterogeneous oxidation catalysts. MOFs are very promising candidates to replace homogeneous catalysts by sustainable and stable heterogeneous catalysts. The catalytic active function can be either the active metal sites of the MOF itself or can be introduced as an extra functionality in the linker, a dopant or a "ship-in-a-bottle" complex. As the pore size, pore shape and functionality of MOFs can be designed in numerous ways, shape selectivity and even chiral selectivity can be created. In this review, we will present an overview on the state of the art of the use of MOFs as a heterogeneous catalyst in liquid phase oxidation reactions.

Porous aromatic framework (PAF-1) as hyperstable platform for enantioselective organocatalysis

“…The peak corresponding to the aliphatic quaternary carbon linked by four benzene rings was observed at 64 ppm and the peaks corresponding to the aromatic carbons were observed at 117−152 ppm in the spectrum. In a word, the peaks in the 13 C NMR spectrum agree well with the designed immobilized catalyst, which confirms that the Lprolinamide catalyst has been well embedded into the PAF material.…”

“…2). The solid-state 13 C NMR (Fig. 2) of PAF-1-NHPro showed one broad peak around 170 ppm which was the characteristic peak of the amide carbon.…”

“…The chemical composition of PAF-1-NHPro was further characterized by solid-state 13 C CP/MAS TOSS NMR spectroscopy (Fig. 2).…”

“…Fourier transform infrared (FT-IR) spectra were recorded on a Bruker IFS 66v/S Fourier transform infrared spectrometer. The solid state 13 C CP/MAS TOSS (cross-polarization/magic-angle spinning total suppression of spinning sidebands) NMR spectrum was measured on Bruker Avance III WB 400 spectrometer with magic angle spinning at 8 kHz frequency. Powder X-ray diffraction (PXRD) was performed by a Rigaku D/ MAX2550 diffractometer using Cu-Kα radiation, 40 kV, 200 mA with a scanning rate of 1°min −1 (2θ).…”

“…Among the applications, immobilization of homogeneous catalysts, especially chiral catalysts, on cavity surfaces of the solid porous materials is of great importance. In this field, the latest developments involved enantioselective catalysis based on metal-organic frameworks (MOFs) [1][2][3][4][5][6][7][8][9][10][11][12][13][14], covalent organic frameworks (COFs) [15][16][17][18][19][20][21][22][23][24] and porous organic polymers (POPs) [25][26][27][28][29][30][31][32]. Many advantages of MOFs, COFs and POPs for heterogeneous enantioselective catalysis have been elaborated by scientists.…”