Anchorage of Au3+ into Modified Isoreticular Metal–Organic Framework-3 as a Heterogeneous Catalyst for the Synthesis of Propargylamines

Abstract

Postsynthetic modification of metal-organic framework is a general and practical approach to access MOF-based catalysts bearing multiple active sites. The isoreticular metal–organic framework-3 (IRMOF-3) was modified with lactic acid through condensation reaction of the carboxyl group of lactic acid and amino group present in IRMOF-3 frameworks. Au3+ was subsequently anchored onto the metal–organic framework IRMOF-3 using postsynthetic modification. The synthezized IRMOF-3-LA-Au (LA = lactic acid) was characterized by powder X-ray diffraction, N2 adsorption-desorption, infrared spectroscopy, liquid-state nuclear magnetic resonance, thermogravimetric analysis, H2-temperature programmed reduction, transmission electro microscopy, and inductively coupled plasma–optical emission spectrometry. IRMOF-3-LA-Au acted as an efficient heterogeneous catalyst in the synthesis of propargylamines by three-component coupling reaction of aldehyde, alkyne, and amine. Moreover, the catalyst is applicable to various substituted substrates, including aromatic and aliphatic aldehydes, alkyl- and aryl-substituted terminal alkynes, and alicyclic amines. In addition, the catalyst can be easily separated from the mixture and can be reused for four consecutive cycles.

Oxidation or Reduction State of Au Stabilized by an MOF: Active Site Identification for the Three‐Component Coupling Reaction

“…For example, Liu et al sythesized an Au/MIL‐53(Al) catalyst‐containing Au 0 and Au 3+ species, which display good activity for the A 3 coupling reaction . In addition, Liu et al also demonstrated the Au 3+ ‐containing catalyst, IRMOF‐3‐LA‐Au, can exhibit good performance in the A 3 coupling reaction . Some comparative studies have been attempted, such as the contrastive properties of gold salts and Au 0 sponges, or the activity comparison between Au NPs/PMO (PMO = periodic mesoporous organosilica) and Au(PPh 3 )Cl .…”

“…Compared with Au/MIL‐53(Al) catalyst fabricated via the impregnation method with HAuCl 4 , the hydroxyl and imine groups of MIL‐101‐SA can provide strong chelating/anchor sites to immobilize Au ions, rather than being adsorbed on the surfaces or pores of the MOF. Furthermore, in reference to IRMOF‐3‐LA‐Au (LA = lactic acid) catalyst, MIL‐101‐SA‐M exhibits much better water stability that allows the reaction to proceed in water and avoids the use of organic solvent. In a word, MIL‐101‐SA possesses excellent structural stability and chelating sites to stabilize Au species, making the resulting catalysts steadily catalyze the A 3 reaction in water.…”

Polymer Beads Decorated with Dendritic Systems as Supports for A3 Coupling Catalysts

“…To perform the A 3 coupling effectively, the selective and active catalysts are required. Numerous catalytic systems have been explored in the A 3 coupling till now [30][31][32][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60]. Among them copper, silver and gold catalysts seem to play the most vital role in promoting these transformations [30,32,[44][45][46].…”

“…Among them copper, silver and gold catalysts seem to play the most vital role in promoting these transformations [30,32,[44][45][46]. Though the homogeneous version of A 3 couplings shows the high efficiency, the difficulties in catalyst reusability and product purification cause that, currently, the various heterogeneous catalysts, including immobilized metal complexes [30,34,47,48], coordination compounds [49,50] and nanocatalysts [30,32,[51][52][53][54][55] are examined intensively. The heterogeneous catalysts allow to limit polluting the final products with toxic metal species when the proper supports are selected.…”

Iron oxide modified with pyridyl‐triazole ligand for stabilization of gold nanoparticles: An efficient heterogeneous catalyst for A3 coupling reaction in water

“…It should be noted that homogeneous catalysts suffer from the problem of catalyst separation and reuse, and also the problem of product contamination with generally toxic transition metals. Recently, a few heterogeneous and recyclable gold catalysts have been reported for A 3 coupling reactions . Along this line, recyclable gold nanoparticles (NPs) of 20 nm in size have been reported for the synthesis of propargylamines in CH 3 CN under efficient reaction conditions …”