Site-Isolated Azobenzene-Containing Metal–Organic Framework for Cyclopalladated Catalyzed Suzuki-Miyuara Coupling in Flow

Abstract

Sites isolation of active metals centers, systematically studied in homogeneous systems, has been an alternative to develop low metal consuming, highly active next generation catalysts in heterogeneous condition. Because of the high porosity and facile synthetic procedures, MOF-based catalysts are excellent candidates for heterogenization of well-defined homogeneous catalysts. Herein, we report the direct Pd coordination on the azobenzene linker within a MOF catalyst through a postsynthetic modification method for a Suzuki−Miyaura coupling reaction. The immobilized cyclopalladated complexes in MOFs were analyzed by a series of characterization techniques including XPS, PXRD, and deuterium NMR ( 2 H NMR) spectroscopy. The heterogeneous nature of the catalyst as well as its stability were demonstrated though "hot filtration" and recycling experiments. Furthermore, we demonstrate that the MOF packed column promoted the reaction between phenyl boronic acid and bromobenzene under microflow conditions with a 85% yield continuously for 12 h. This work sheds light on the potential of site-isolated MOF catalysts in efficient, recyclable and continuous flow systems for industrial application.

Palladium‐Based Metal Organic Frameworks as Heterogeneous Catalysts for C−C Couplings

“…Furthermore, XPS and 1 H‐NMR proved that the single molecular Pd(II) species were cyclometalated palladium complexes (see Figure 4). [76] The solid was employed as a catalyst (0.8 mol% Pd) in the Suzuki‐Miyaura coupling of bromobenzene with phenylboronic acid at 90 °C in toluene, using K 2 CO 3 as a base. The product yield was 95 % with a TON value of 119 after 12 h which is like the yield obtained with a mixture of homogeneous PdCl 2 catalyst and the azobenzene dicarboxylate linker (90 %).…”

Two Solvent-Induced In(III)-Based Metal–Organic Frameworks with Controllable Topology Performing High-Efficiency Separation of C2H2/CH4 and CO2/CH4

“…5,6 In light of the cost-effectiveness and environmental compatibility, non-thermally driven separation and purification processes using porous materials have obvious advantages over those using traditional porous materials. 7−12 Metal−organic frameworks (MOFs), which consist of organic linkers and metal ions, have become strong competitors with their controllable structure and adjustable porosity, 13−15 resulting in other potential applications, including gas sorbents, 16−19 light-emitting sensors, 20 catalysis, 21,22 and optical and magnetic materials. 23 On the basis of the engineering of the size and chemistry of the host framework, to improve the host−guest interaction, Lewis-based organic ligands (such as -NH 2 , -OH, and pyridine groups) are usually used as the main strategy for MOF material development for the separation and purification of gases.…”

A Metal‐Organic Framework (MOF)‐Based Multifunctional Cargo Vehicle for Reactive‐Gas Delivery and Catalysis

“…Due to their toxicity and reactivity, expensive safety measures are required to handle, store, and transport these gases safely, thereby placing their usage in synthetic chemistry under strict regulations [7] . Herein, we probed metal‐organic frameworks (MOFs), [8–33] specifically their reversible gas adsorption and catalytic activity, to carry out chemical reactions in organic solvents. Thus, we explored the dual role of MOFs as a catalyst and carrier of reagents on the example of reactive gases.…”