Having access to clean water is a mandatory requirement for the proper development of living beings.

The development of catalysts able to assist industrially important chemical processes is a topic of high importance. In view of the catalytic capabilities of small metal clusters, research efforts are being focused on the synthesis of novel catalysts bearing such active sites. Here we report a heterogeneous catalyst consisting of Pd clusters with mixed-valence 0/+1 oxidation states, stabilized and homogeneously organized within the walls of a metal-organic framework (MOF). The resulting solid catalyst outperforms state-of-the-art metal catalysts in carbene-mediated reactions of diazoacetates, with high yields (>90%) and turnover numbers (up to 100,000). In addition, the MOF-supported Pd clusters retain their catalytic activity in repeated batch and flow reactions (>20 cycles). Our findings demonstrate how this synthetic approach may now instruct the future design of heterogeneous catalysts with advantageous reaction capabilities for other important processes.

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.

A robust and water-stable metal-organic framework (MOF), featuring hexagonal channels decorated with methionine residues (1), selectively captures toxic species such as CH3 Hg(+) and Hg(2+) from water. 1 exhibits the largest Hg(2+) uptake capacity ever reported for a MOF, decreasing the [Hg(2+) ] and [CH3 Hg(+) ] concentrations in potable water from highly hazardous 10 ppm to the much safer values of 6 and 27 ppb, respectively. Just like with biological systems, the high-performance metal capture also involves a molecular recognition process. Both CH3 Hg(+) and Hg(2+) are efficiently immobilized by specific conformations adopted by the flexible thioether "claws" decorating the pores of 1. This leads to very stable structural conformations reminiscent of those responsible for the biological activity of the enzyme mercury reductase (MR).

The gram-scale synthesis, stabilization, and characterization of well-defined ultrasmall subnanometric catalytic clusters on solids is a challenge. The chemical synthesis and X-ray snapshots of Pt clusters, homogenously distributed and densely packaged within the channels of a metal-organic framework, is presented. This hybrid material catalyzes efficiently, and even more importantly from an economic and environmental viewpoint, at low temperature (25 to 140 °C), energetically costly industrial reactions in the gas phase such as HCN production, CO methanation, and alkene hydrogenations. These results open the way for the design of precisely defined catalytically active ultrasmall metal clusters in solids for technically easier, cheaper, and dramatically less-dangerous industrial reactions.

We report a new water-stable multivariate (MTV) metal–organic framework (MOF) prepared by combining two different oxamide-based metalloligands derived from the natural amino acids l-serine and l-methionine. This unique material features hexagonal channels decorated with two types of flexible and functional “arms” (−CH2OH and −CH2CH2SCH3) capable of enabling, synergistically, the simultaneous and efficient removal of both inorganic (heavy metals such as Hg2+, Pb2+, and Tl+) and organic (dyes such as Pyronin Y, Auramine O, Brilliant green, and Methylene blue) contaminants, and, in addition, this MTV-MOF is completely reusable. Single-crystal X-ray diffraction measurements allowed solving the crystal structure of a host–guest adsorbate, containing both HgCl2 and Methylene blue, and offered unprecedented snapshots of this unique dual capture process. This is the very first time that a MOF can be used for the removal of all sorts of pollutants from water resources, thus opening new perspectives for this emerging type of MTV-MOF.

The search for simple, earth-abundant, cheap, and nontoxic metal catalysts able to perform industrial hydrogenations is a topic of interest, transversal to many catalytic processes. Here, we show that isolated Fe-O sites on solids are able to dissociate and chemoselectively transfer H to acetylene in an industrial process. For that, a novel, robust, and highly crystalline metal-organic framework (MOF), embedding Fe-OH single sites within its pores, was prepared in multigram scale and used as an efficient catalyst for the hydrogenation of 1% acetylene in ethylene streams under front-end conditions. Cutting-edge X-ray crystallography allowed the resolution of the crystal structure and snapshotted the single-atom nature of the catalytic Fe-O site. Translation of the active site concept to even more robust and inexpensive titania and zirconia supports enabled the industrially relevant hydrogenation of acetylene with similar activity to the Pd-catalyzed process.

High-nuclearity complexes of transition-metal ions have been of special interest during the last two decades owing to the possibility of observing slow magnetic relaxation effects at the molecular level. [1] These molecular nanomagnets have potential applications as new high-density magnetic memories and quantum-computing devices in the field of molecular spintronics. [2] The first example of a discrete molecule exhibiting hysteresis and quantum tunneling of the magnetization was the mixed-valent dodecanuclear manganese(III,IV) complex [Mn 12 O 12 (CH 3 CO 2 ) 16 (H 2 O) 4 ]. [3] Since then, a plethora of both homo-and heterovalent, manganese-based molecular nanomagnets of varying metal oxidation states (i.e., Mn II , Mn III and/or Mn IV ) have been reported, with nuclearities from up to [Mn III 84 ] down to the smaller [Mn III 2 ] species. [4] However, to our knowledge, there are no examples of mononuclear manganese complexes exhibiting the slow magnetic relaxation effects typical of molecular nanomagnets, referred to as single-ion magnet (SIMs). This is somewhat puzzling, since several SIMs of other highly anisotropic first-row transition metals (i.e., Co II and Fe I/II/III ) have been recently reported which has rekindled the debate in the field of singlemolecular magnetism. [5] The six-coordinated octahedral high-spin d 4 Mn III ion (S = 2) has an orbitally degenerate 5 E g ground electronic term that is split by the Jahn-Teller effect into 5 A 1g and 5 B 1g orbital singlet low-lying states. Owing to the large mixing between them, second-order spin-orbit coupling (SOC) effects are ultimately responsible for the occurrence of a large axial magnetic anisotropy whose sign depends on the ground state, that is, on the nature of the axial tetragonal distortion. [6] For an axially elongated octahedral Mn III environment, negative D values are expected that can potentially lead to a large energy barrier for the magnetization reversal between the two lowest M S =AE 2 states. To provide this type of geometry and obtain manganese(III)-based SIMs, planar tetradentate chelating ligands with strong donor groups are a well-suited choice. [7] Herein, we report a complete study on the synthesis, structural characterization, spectroscopic and magnetic properties, and theoretical calculations of Ph 4 P[Mn(opbaCl 2 )(py) 2 ] (1) [H 4 opbaCl 2 = N,N'-3,4-dichloro-o-phenylenebis(oxamic acid), py = pyridine, and Ph 4 P + = tetraphenylphosphonium cation]. Complex 1 is the first example of a mononuclear manganese(III) complex exhibiting a field-induced slow magnetic relaxation behavior, thus increasing the number of first-row transition-metal-ion SIMs.Complex 1 was obtained as well-formed deep brown cubic prisms by slow evaporation of a methanol/pyridine (1:4 v/v) solution of its tetramethylammonium salt in the presence of an excess of Ph 4 PCl (see Supporting Information). It crystallizes in the P2 1 /c space group of the monoclinic system (Table S1, Supporting Information). The crystal structure of 1 consists of mononuclear m...