The preparation of novel efficient catalyststhat could be applicable in industrially important chemical processeshas attracted great interest. Small subnanometer metal clusters can exhibit ...outstanding catalytic capabilities, and thus, research efforts have been devoted, recently, to synthesize novel catalysts bearing such active sites. Here, we report the gram-scale preparation of Ag2 0 subnanometer clusters within the channels of a highly crystalline three-dimensional anionic metal–organic framework, with the formula Ag2 0@AgI 2NaI 2{NiII 4CuII 2(Me3mpba)23}·48H2O Me3mpba4– = N,N′-2,4,6-trimethyl-1,3-phenylenebis(oxamate). The resulting crystalline solid catalystfully characterized with the help of single-crystal X-ray diffractionexhibits high catalytic activity for the catalytic Buchner ring expansion reaction.
A novel chiral 3D bioMOF exhibiting functional channels with thio-alkyl chains derived from the natural amino acid l-methionine (1) has been rationally prepared. The well-known strong affinity of ...gold for sulfur derivatives, together with the extremely high flexibility of the thioether “arms” decorating the channels, account for a selective capture of gold(III) and gold(I) salts in the presence of other metal cations typically found in electronic wastes. The X-ray single-crystal structures of the different gold adsorbates Au III @1 and Au I @1 suggest that the selective metal capture occurs in a metal ion recognition process somehow mimicking what happens in biological systems and protein receptors. Both Au III @1 and Au I @1 display high activity as heterogeneous catalyst for the hydroalkoxylation of alkynes, further expanding the application of these novel hybrid materials.
Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need ...of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium single atoms are spontaneously formed after dissolving tiny amounts of palladium salts in neat benzyl alcohols, to catalyze their direct aerobic oxidation to benzoic acids without ligands, additives, or solvents. With this result in hand, the gram-scale preparation and stabilization of Pd SACs within the functional channels of a novel methyl-cysteine-based metal–organic framework (MOF) was accomplished, to give a robust and crystalline solid catalyst fully characterized with the help of single-crystal X-ray diffraction (SCXRD). These results illustrate the advantages of metal speciation in ligand-free homogeneous organic reactions and the translation into solid catalysts for potential industrial implementation.
The presence of residual organic dyes in water resources or wastewater treatment systems, derived mainly from effluents of different industries, is a major environmental problem with no easy ...solution. Herein, an ecofriendly, water‐stable metal–organic framework was prepared from a derivative of the natural amino acid l‐serine. Its functional channels are densely decorated with highly flexible l‐serine residues bearing hydroxyl groups. The presence of such a flexible and functional environment within the confined environment of the MOF leads to efficient removal of different organic dyes from water: Pyronin Y, Auramine O, Methylene Blue and Brilliant Green, as unveiled by unprecedented snapshots offered by single‐crystal X‐ray diffraction. This MOF enables highly efficient water remediation by capturing more than 90 % of dye content, even at very low concentrations such as 10 ppm, which is similar to those usually found in industrial wastewaters. Remarkably, the removal efficiency is improved in simulated contaminated mineral water with multiple dyes.
Multidye capture: A highly crystalline metal–organic framework, derived from the amino acid l‐serine, captures efficiently different organic dyes at very low concentration, even in the presence of multiple dyes (see figure). In addition, single‐crystal X‐ray diffraction offered unprecedented snapshots of the dye‐capture process.
A single crystal to single crystal transmetallation process takes place in the three‐dimensional (3D) metal–organic framework (MOF) of formula MgII2{MgII4CuII2(Me3mpba)23}⋅45 H2O (1; ...Me3mpba4−=N,N′‐2,4,6‐trimethyl‐1,3‐phenylenebis(oxamate)). After complete replacement of the MgII ions within the coordination network and those hosted in the channels by either CoII or NiII ions, 1 is transmetallated to yield two novel MOFs of formulae Co2II{CoII4CuII2(Me3mpba)23}⋅56 H2O (2) and Ni2II{NiII4CuII2(Me3mpba)23}⋅ 54 H2O (3). This unique postsynthetic metal substitution affords materials with higher structural stability leading to enhanced gas sorption and magnetic properties.
Synthesis à la carte: A single crystal to single crystal transmetallation process is reported in a metal–organic framework in which MgII ions within the coordination network (see picture; orange polyhedra) and those hosted in the channels (orange spheres) are replaced entirely by either CoII or NiII ions (purple spheres and polyhedra).
The exact chemical structure of non-crystallising natural products is still one of the main challenges in Natural Sciences. Despite tremendous advances in total synthesis, the absolute structural ...determination of a myriad of natural products with very sensitive chemical functionalities remains undone. Here, we show that a metal-organic framework (MOF) with alcohol-containing arms and adsorbed water, enables selective hydrolysis of glycosyl bonds, supramolecular order with the so-formed chiral fragments and absolute determination of the organic structure by single-crystal X-ray crystallography in a single operation. This combined strategy based on a biomimetic, cheap, robust and multigram available solid catalyst opens the door to determine the absolute configuration of ketal compounds regardless degradation sensitiveness, and also to design extremely-mild metal-free solid-catalysed processes without formal acid protons.
On the road to chemical sensors: A novel 2D oxamato‐based manganese(II)‐copper(II) mixed‐metal–organic framework (M'MOF) exhibiting non‐linear fluorescence and long‐range magnetic ordering is ...reported. This new luminescent nanoporous magnet features highly selective solvent‐ and gas sorption‐induced optical switching behavior, opening the door to potential application for sensing of small molecules.
β-Lactam antibiotics are one of the most commonly prescribed drugs to treat bacterial infections. However, their use has been somehow limited given the emergence of bacteria with resistance ...mechanisms, such as β-lactamases, which inactivate them by degrading their four-membered β-lactam rings. So, a total knowledge of the mechanisms governing the catalytic activity of β-lactamases is required. Here, we report a novel Zn-based metal-organic framework (MOF, 1), possessing functional channels capable to accommodate and interact with antibiotics, which catalyze the selective hydrolysis of the penicillinic antibiotics amoxicillin and ceftriaxone. In particular, MOF 1 degrades, very efficiently, the four-membered β-lactam ring of amoxicillin, acting as a β-lactamase mimic, and expands the very limited number of MOFs capable to mimic catalytic enzymatic processes. Combined single-crystal X-ray diffraction (SCXRD) studies and density functional (DFT) calculations offer unique snapshots on the host-guest interactions established between amoxicillin and the functional channels of 1. This allows to propose a degradation mechanism based on the activation of a water molecule, promoted by a Zn-bridging hydroxyl group, concertedly to the nucleophilic attack to the carbonyl moiety and the cleaving of C-N bond of the lactam ring.
Abstract
Invited for the cover of this issue are Jesús Ferrando‐Soria, Donatella Armentano, Antonio Leyva‐Pérez, Emilio Pardo and co‐workers at University of Valencia, Technical University of ...Valencia and University of Calabria. The image depicts the crystal structure of a novel Zn
II
biological metal–organic framework that mimics β‐lactamase enzymes. Read the full text of the article at
10.1002/chem.202301325
.
Extremely high electrophilic metal complexes, composed by a metal cation and very electron poor σ‐donor ancillary ligands, are expected to be privileged catalysts for oxidation reactions in organic ...chemistry. However, their low lifetime prevents any use in catalysis. Here we show the synthesis of fluorinated pyridine‐Pd2+ coordinate cages within the channels of an anionic tridimensional metal‐organic framework (MOF), and their use as efficient metal catalysts for the aerobic oxidation of aliphatic alcohols to carboxylic acids without any additive. Mechanistic studies strongly support that the MOF‐stabilized coordination cage with perfluorinated ligands unleashes the full electrophilic potential of Pd2+ to dehydrogenate primary alcohols, without any base, and also to activate O2 for the radical oxidation to the aldehyde intermediate. This study opens the door to design catalytic perfluorinated complexes for challenging organic transformations, where an extremely high electrophilic metal site is required.
Fluorinated pyridine‐Pd2+ coordinate cages have been synthesized and characterized with atomic resolution within the channels of a metal‐organic framework (MOF), and used as catalysts during the aerobic oxidation of aliphatic alcohols to carboxylic acids without any additive. These results illustrate a rare example of stable per‐fluorinated cationic metal complex, with potential implications in the future design of catalytic organometallic complexes.
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