Jérôme Canivet

MOF-Supported Selective Ethylene Dimerization Single-Site Catalysts through One-Pot Postsynthetic Modification

The one-pot postfunctionalization allows anchoring a molecular nickel complex into a mesoporous metal-organic framework (Ni@(Fe)MIL-101). It is generating a very active and reusable catalyst for the liquid-phase ethylene dimerization to selectively form 1-butene. Higher selectivity for 1-butene is found using the Ni@(Fe)MIL-101 catalyst than reported for molecular nickel diimino complexes.

Dynamic Nuclear Polarization Enhanced Solid‐State NMR Spectroscopy of Functionalized Metal–Organic Frameworks

Dynamic nuclear polarization (DNP) is applied to enhance the signal of solid-state NMR spectra of metal-organic framework (MOF) materials. The signal enhancement enables the acquisition of high-quality 1D 13C solid-state NMR spectra, 2D 1H-13C dipolar HETCOR and 1D 15N solid-state NMR spectra with natural isotopic abundance in experiment times on the order of minutes.

Water-soluble arene ruthenium catalysts containing sulfonated diamine ligands for asymmetric transfer hydrogenation of α-aryl ketones and imines in aqueous solution

A new family of nine cationic organometallic aqua complexes of the type [(arene)Ru(RSO2N∩NH2)(OH2)]+ (1–9), containing chiral N,N-chelating ligands, has been synthesised and isolated as the tetrafluoroborate salts, which are water-soluble and stable to hydrolysis. The enantiopure complexes 1–9 catalyse the transfer hydrogenation of prochiral aryl ketones and imines in aqueous solution to give the corresponding alcohols and amines with good conversion and enantioselectivity. This method gives an environmentally friendly access, for instance, to isoquinoline alkaloids by asymmetric catalysis in water.

Engineering structured MOF at nano and macroscales for catalysis and separation

Here, we present for the first time the combination of the postfunctionalization of a MOF with its shaping as structured bodies. This study deals with the porous zinc carboxylimidazolate material known as SIM-1. A great advantage of this method is that the aldehyde moieties present on the structure walls allow organic modifications in the solid state, such as imine synthesis by condensation with primary amines to give the corresponding imino-functionalized SIM-2. We show that this postfunctionalization can be carried out on shaped SIM-1 bodies and films. The parent SIM-1 structured materials are prepared by direct in situ synthesis on a variety of supports for catalysis such as alumina beads and cordierite monoliths, and for separation applications using supports such as alumina tubes, fibers and anodic alumina disks. The hydrophobic SIM-2(C12) prepared on alumina beads is found to be an active catalyst for the Knoevenagel condensation, while its analogous supported membrane on alumina tube is efficient for CO2/N2 separation under humid conditions.

Enantiopure Peptide-Functionalized Metal-Organic Frameworks.

We present herein the first example of metal-organic frameworks postfunctionalized with peptides. Our microwave-assisted postsynthetic modification method yields enantiopure peptides anchored inside MOF cavities. Al-MIL-101-NH2, In-MIL-68-NH2, and Zr-UiO-66-NH2 were chosen as starting platforms. A single amino acid and various oligopeptides are grafted with yields up to 60% after a 30 min microwave-assisted coupling-deprotection sequence. This allows efficient preparation of a library of functional hybrid solids for molecular recognition applications such as sensing, separation, or asymmetric catalysis, as demonstrated here for the chiral aldol reaction.

Structure–property relationships of water adsorption in metal–organic frameworks

A set of 15 metal–organic frameworks (MIL-53, MIL-68, MIL-125, UiO-66, ZIF) exhibiting different pore size, morphology, and surface chemistry is used to unravel the numerous behaviors of water adsorption at room temperature in this class of materials. Outstanding “S”-shaped (type V) adsorption isotherms are observed for MIL-68 type solids. We show that the underlying mechanism of water adsorption can be rationalized using a simple set of three parameters: the Henry constant (i.e. the slope of the adsorption pressure in the low pressure range), the pressure at which pore filling occurs, and the maximum water adsorption capacity. While the Henry constant and pore filling pressure mostly depend on the affinity of water for the surface chemistry and on pore size, respectively, these two parameters are correlated as they both reflect different aspects of the hydrophobicity–hydrophilicity of the material. For a given type of porous structure, the functionalization of the material by hydrophilic moieties such as hydrogen bonding groups (amine or aldehyde) systematically leads to an increase in the Henry constant concomitantly with a decrease in the pore filling pressure. As for the adsorption mechanism, we show that, for a given temperature, there is a critical diameter (Dc ∼ 20 A for water at room temperature) above which pore filling occurs through irreversible capillary condensation accompanied by capillary hysteresis loops. Below this critical diameter, pore filling is continuous and reversible unless the material exhibits some adsorption-induced flexibility.

Photocatalytic Carbon Dioxide Reduction with Rhodium‐based Catalysts in Solution and Heterogenized within Metal–Organic Frameworks

The first photosensitization of a rhodium-based catalytic system for CO2 reduction is reported, with formate as the sole carbon-containing product. Formate has wide industrial applications and is seen as valuable within fuel cell technologies as well as an interesting H2 -storage compound. Heterogenization of molecular rhodium catalysts is accomplished via the synthesis, post-synthetic linker exchange, and characterization of a new metal-organic framework (MOF) Cp*Rh@UiO-67. While the catalytic activities of the homogeneous and heterogeneous systems are found to be comparable, the MOF-based system is more stable and selective. Furthermore it can be recycled without loss of activity. For formate production, an optimal catalyst loading of ∼10 % molar Rh incorporation is determined. Increased incorporation of rhodium catalyst favors thermal decomposition of formate into H2 . There is no precedent for a MOF catalyzing the latter reaction so far.

Engineering the Environment of a Catalytic Metal–Organic Framework by Postsynthetic Hydrophobization

Heterogeneous catalysis is of paramount importance in many areas of the chemical and energy industries. Often, however, reactions can be hindered or reaction rates limited by poisoning effects originating from moisture in the air or from the water formed during the organic transformation. Water can be adsorbed and block catalytic sites, leading to their deactivation. This drawback has motivated the design and engineering of catalytic materials with hydrophobic features, such as the hydrophobic outer shell of enzymes, to prevent water-induced catalyst poisoning. Metal–organic frameworks (MOFs) represent an extensive class of porous organic–inorganic crystalline materials. Due to their calibrated pore size, they are regarded as new shapeselective catalysts analogous to zeolites. MOFs have already been reported to catalyze a broad range of organic transformations involving their Lewis acid nodes as well as their Brønsted acid–base properties. 13] Many reports have dealt with carbon–carbon bond formation catalyzed by unmodified MOFs through reactions such as Suzuki–Miyaura cross-coupling, the Mukaiyama aldol reaction, alkylation 17] or polymerization. 19] To obtain more sophisticated MOF catalysts, many research groups have examined the functionalization of these materials. The post-synthetic modification (PSM) of MOFs, an appealing route toward functionalized frameworks, involves chemical modification of the solid after formation of the crystalline structure, assuming that the primitive MOFs employed are sufficiently porous and robust. Post-synthetic modification can provide a wide range of isotopological structures from a single MOF by treating it as a substrate with a variety of organic reagents. The insertion of pendant groups onto or into the MOF makes it possible to add chemical functionality while retaining the MOF’s overall framework. Cohen and co-workers extensively studied the covalent organic PSM of a variety of amino-functionalized MOFs. This strategy was used by his group and others to generate metal complexes on MOFs, creating a new class of Lewis acid catalysts. 23, 30] Furthermore, Cohen extended his study to the hydrophobization of amino-containing MOFs through amide coupling, in order to increase their moisture resistance. In a parallel work, Yaghi et al. also reported the functionalization of porous materials and especially the reactivity of ZIF-90 against an amine or a reducing agent. The effect of the functionalization of a MOF by hydrophobic agents on its catalytic activity has, however, not been reported to date. In contrast to previous studies, our methodology is based on the modification of the environment of the catalytic centers and not on the insertion of new sites onto the MOF structure. We therefore studied the ability of modified zeolitic imidazolate framework (ZIF) materials to accelerate the rate of a reaction involving water formation. We chose the Knoevenagel condensation, which is a crossed aldol condensation of a carbonyl compound with an active methylene compound leading to C=C bond formation. This reaction is widely applied in the synthesis of fine chemicals and is classically catalyzed by bases in solution. This reaction can also be catalyzed by solid bases, such as metal oxides. The water that is produced in the course of the reaction usually competes with substrates for adsorption, however, thereby acting as a poison. Porous solids such as modified SBA-1, zeolites, 37] MIL-101 (TOF= 328 h ), 39] IRMOF-3 (TOF = 180 h ) or MIL-53, and others have already been employed as active heterogeneous catalysts for the Knoevenagel reaction. We report herein the fine tuning of hydrophobic properties of a MOF by post-synthetic modification to optimize its catalytic properties. To our knowledge, this is the first study showing that the engineering of the hydrophobic/hydrophilic environment can enhance the catalytic activity of a MOF by an order of magnitude. Our work focused on a porous substituted imidazolate material (SIM-1, formulated C10H10N4O2Zn) discovered by our group and belonging to the class of ZIFs. SIM-1 is a robust material, isostructural to ZIF-8 and consisting of ZnN4 tetrahedra linked by carboxylimidazolates. The aldehyde moiety present on the structure walls allows organic modification in the solid state, such as imine synthesis by condensation with primary amines to give the corresponding imino-functionalized SIM-2. This SIM-1 functionalization by imine condensation proceeds under mild conditions. In a typical experiment, a sample of desorbed SIM-1 (50 mg) was suspended in anhydrous methanol (5 mL) and the desired amine (1 mmol) was added under stirring. The suspension was allowed to react at room temperature for 24 h. After reaction, the solid was centrifuged and washed three times with ethanol and then dried under vacuum, providing the corresponding SIM-2 as a crystalline offwhite powder. In this manner, SIM-1 was treated with the primary amines dodecylamine to give SIM-2(C12) (Scheme 1). The C12 aliphatic chains present at the surface of the material create a hydrophobic shell surrounding the framework. Powder XRD analysis of the SIM-2(C12) sample showed a slight loss of crystallinity despite retention of the initial structure. Notably, the porosity of the SIM materials was maintained [a] Dr. J. Canivet, Dr. S. Aguado, C. Daniel, Dr. D. Farrusseng Universit Lyon 1, IRCELYON, Institut de Recherches sur la Catalyse et l’Environnement de Lyon, UMR CNRS 5256 Avenue Albert Einstein 2, 69626 Villeurbanne (France) Fax: (+ 33) 4-72-44-54-36 E-mail : david.farrusseng@ircelyon.univ-lyon1.fr Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cctc.201000386.

Antimicrobial activity of cobalt imidazolate metal–organic frameworks

Two cobalt imidazolate metal-organic frameworks were evaluated as a bactericidal material against the growth of the Gram-negative bacteria Pseudomonas putida and Escherichia coli. Under the most unfavourable conditions, within the exponential growth phase and in the culture media for both microorganisms, the growth inhibition reached over 50% for concentrations of biocidal material in the 5-10mgL(-1) range. The release of metal gives excellent durability with the antibacterial effect persisting after 3months. Both cobalt-based materials can be prepared with simple, cheap and easily accessible commercial ligands, leading to a more affordable possible future application as antimicrobial materials.

Superstructure of a Substituted Zeolitic Imidazolate Metal–Organic Framework Determined by Combining Proton Solid‐State NMR Spectroscopy and DFT Calculations

We report the supercell crystal structure of a ZIF-8 analog substituted imidazolate metal-organic framework (SIM-1) obtained by combining solid-state nuclear magnetic resonance and powder X-ray diffraction experiments with density functional theory calculations.