Palladium Nanoparticles Encapsulated in a Metal–Organic Framework as Efficient Heterogeneous Catalysts for Direct C2 Arylation of Indoles

Abstract

Highly dispersed palladium nanoparticles (Pd NPs) encapsulated in the mesoporous cages of the metal-organic framework (MOF) MIL-101(Cr) have been prepared by using the wetness impregnation method. The Pd NPs were characterized by powder X-ray diffraction (PXRD), N(2) adsorption, transmission electron microscopy, inductively coupled plasma atomic emission spectroscopy (ICP-AES), and X-ray photoelectron spectroscopy (XPS). The particles size ((2.6±0.5) nm) of the obtained Pd NPs was in good agreement with the cage diameters (2.9 and 3.4 nm) of the MOF. The resulting Pd/MIL-101(Cr) catalyst exhibited extremely high catalytic activities in the direct C2 arylation of substituted indoles by using only 0.1 mol% of the Pd catalyst. Moreover, the catalyst is easily recoverable and can be reused several times without leaching into solution and loss of activity. The combination of the highly dispersible Pd NPs within the accessible mesoporous cages and the favorable adsorption of the aryl halides on MIL-101 are suspected to be the main reasons for the observed high activities of the Pd/MIL-101(Cr) catalyst in the direct C2 arylation of indoles.

Facile synthesis of palladium nanoparticles encapsulated in amine-functionalized mesoporous metal–organic frameworks and catalytic for dehalogenation of aryl chlorides

“…The as-synthesized MIL-101(Cr) [51] and MIL-53(Al)-NH 2 [54] were activated according to the literature. MIL-101(Cr)-NO 2 :50 mg MIL-101(Cr) was added to a mixture of 4 ml concentrated sulfuric acid and 3 ml concentrated nitric acid at 0°C.…”

“…Inclusion of metallic nanoparticles in MOFs still remains a challenge [38][39][40][41][42][43][44][45][46][47][48]. So far, there are only a handful of MOF materials as host matrices to support metal NPs as catalysts for heterogeneous catalysis [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] 3 ÁnH 2 O (n % 25) for the success of encapsulation of noble metal nanoparticles [39]. We also synthesized well-dispersed Pd nanoparticles (Pd NPs) supported on the amino-functionalized MOF MIL-53(Al)-NH 2 (Al(OH)[H 2 N-BDC], H 2 N-BDC = 2-aminoterephthalic acid, MIL = Materials of Institut Lavoisier) using a direct anionic exchange approach [52,53].…”

A Co/metal–organic-framework bifunctional electrocatalyst: The effect of the surface cobalt oxidation state on oxygen evolution/reduction reactions in an alkaline electrolyte

“…These improved activities were attributed to the enhancement of MIL-101(Cr) with a high stability, high porosity and open framework, indicating that MIL-101(Cr) can be used as an excellent electrocatalyst support [40]. In addition, the large pore size of MIL-101(Cr) affords the space for accommodating guest species such as Keggin anions [41] and metal nanoparticles [42]. In this study, we employ MIL-101(Cr) as the support to design and synthesize a Co-based bifunctional electrocatalyst as illustrated in Scheme 1.…”

Application of metal and metal oxide nanoparticles@MOFs

“…Such transformations include Suzuki-Myaura [94][95][96][97], Sonogashira [97,98], Ulmann [94], and Heck [99] reactions. Compared to other metal M a n u s c r i p t 15 A wide range of applications, including chemical threat detection, medical diagnostics, food/drink quality control, explosives and pollutants detection, requires sensors that detect specific molecules or elements with high selectivity, sensitivity, and speed of analysis [125][126][127]. Typical transduction mechanisms are changes in the electrical, photophysical or mechanical properties of the sensor material when it interacts with the analyte (sensing, Fig.…”