Post‐synthetic Modification of DUT‐5‐based Metal Organic Frameworks for the Generation of Single‐site Catalysts and their Application in Selective Epoxidation Reactions

Abstract

New single‐site catalysts based on mixed‐linker metal‐organic frameworks with DUT‐5 structure, which contain immobilized Co2+, Mn2+ and Mn3+ complexes, have successfully been synthesized via post‐synthetic modification. 2,2’‐Bipyridine‐5,5’‐dicarboxylate linkers were directly metalated, while 2‐amino‐4,4’‐biphenyldicarboxylate linkers were post‐synthetically modified by their conversion to Schiff‐base ligands and a subsequent immobilization of the metal complexes. The resulting materials were used as catalysts in the selective epoxidation of trans‐stilbene and the activities and selectivities of the different catalysts were compared. The influence of various reaction parameters on conversion, yield and selectivity were investigated. Very low catalyst amounts of 0.02 mol % were sufficient to obtain a high conversion of trans‐stilbene using molecular oxygen from air as the oxidant. For cobalt‐containing MOF catalysts, conversions up to 90 % were observed and, thus, they were more active than their manganese‐containing counterparts. Recycling experiments and hot filtration tests proved that the reactions were mainly catalyzed via heterogeneous pathways.

Self-adaptive Metal–Organic Framework Assembles Di-iron Active Sites to Mimic Monooxygenases

“…MOF-253 was synthesized through solvothermal reactions between Al­(NO 3 ) 3 ·9H 2 O and H 2 bpydc (Figure A). − Powder X-ray diffraction (PXRD) studies demonstrated the synthesis of MOF-253 as crystalline white powders, and thermal gravimetric analysis (TGA) supported the chemical formula of Al­(OH) (bpydc) (Figure S2). The treatment of MOF-253 with FeCl 2 in tetrahydrofuran afforded the pre-catalyst 1-pre , which was suspended in methanol and oxidized under an O 2 atmosphere to give the MOF catalyst 1 (Figure B).…”

Pillar-Layered Metal–Organic Frameworks Based on a Hexaprismane [Co6(μ3-OH)6] Cluster: Structural Modulation and Catalytic Performance in Aerobic Oxidation Reaction

“…The reaction conditions, including temperature, dosage of the catalyst, and solvent, were adjusted for the improvement of selectivity of styrene to styrene oxidation, but there was no obvious effect. However, for these typical catalytic reactions, the oxidation atmosphere is one of the important factors for the selectivity of the oxidation products . Herein, when O 2 was replaced by the air, the styrene oxide was obtained as the major product with high selectivity (88%), yet these reactions needed longer time (>10 h) to accomplish (Figure a).…”

Surface-Modified Ultrathin Metal–Organic Framework Nanosheets as a Single-Site Iron Electrocatalyst for Oxygen Evolution Reaction

“…MOFs are usually classified as uniform heterogeneous catalysts, a subclass of single-site heterogeneous catalysts, as the homogeneously distributed unsaturated vacancies of the inorganic node can play the role of catalytic active sites. Alternately, the organic linkers of MOFs can be pre-synthetically or post-synthetically modified with different functional groups, − and the active sites can be controllably introduced into the resulting mixed-linker MOFs, , which combine the advantages of both homogeneous and heterogeneous catalysts, also facilitate the development of quasimolecular heterogeneous catalysts. − The catenation or interpenetration of frameworks, cavity and aperture expansion in the modification process, as well as painful and multistep organic synthesis remain as the main challenges for the preparation of mixed-linker MOF catalysts. , …”