Organic-inorganic supramolecular solid catalyst boosts organic reactions in water

[EN] Coordination polymers and metal-organic frameworks are appealing as synthetic hosts for mediating chemical reactions. Here we report the preparation of a mesoscopic metal-organic structure based on single-layer assembly of aluminium chains and organic alkylaryl spacers. The material markedly accelerates condensation reactions in water in the absence of acid or base catalyst, as well as organocatalytic Michael-type reactions that also show superior enantioselectivity when comparing with the host-free transformation. The mesoscopic phase of the solid allows for easy diffusion of products and the catalytic solid is recycled and reused. Saturation transfer difference and two-dimensional H-1 nuclear Overhauser effect NOESY NMR spectroscopy show that non-covalent interactions are operative in these host-guest systems that account for substrate activation. The mesoscopic character of the host, its hydrophobicity and chemical stability in water, launch this material as a highly attractive supramolecular catalyst to facilitate (asymmetric) transformations under more environmentally friendly conditions.This work was funded by ERC-AdG-2014-671093-SynCatMatch and the Generalitat Valenciana (Prometeo). M.B. acknowledges the funding: CTQ2014-52633-P. The Severo Ochoa program (SEV-2012-0267) is thankfully acknowledged.García García, P.; Moreno Rodríguez, JM.; Díaz Morales, UM.; Bruix, M.; Corma Canós, A. (2016). Organic-inorganic supramolecular solid catalyst boosts organic reactions in water. Nature Communications. 7. https://doi.org/10.1038/ncomms10835S7Li, B. et al. A porous metal-organic framework with dynamic pyrimidine groups exhibiting record high methane storage working capacity. J. Am. Chem. Soc. 136, 6207–6210 (2014).Getman, R. B., Bae, Y.-S., Wilmer, C. E. & Snurr, R. Q. Review and analysis of molecular simulations of methane, hydrogen, and acetylene storage in metal–organic frameworks. Chem. Rev. 112, 703–723 (2012).Suh, M. P., Park, H. J., Prasad, T. K. & Lim, D.-W. Hydrogen storage in metal–organic frameworks. Chem. Rev. 112, 782–835 (2012).Li, B., Wen, H.-M., Zhou, W. & Chen, B. Porous metal-organic frameworks for gas storage and separation: what, how, and why? J. Phys. Chem. Lett. 5, 3468–3479 (2014).Li, J.-R., Sculley, J. & Zhou, H.-C. Metal–organic frameworks for separations. Chem. Rev. 112, 869–932 (2012).Cui, Y., Yue, Y., Qian, G. & Chen, B. Luminescent functional metal–organic frameworks. Chem. Rev. 112, 1126–1162 (2012).Yoon, M., Suh, K., Natarajan, S. & Kim, K. Proton conduction in metal–organic frameworks and related modularly built porous solids. Angew. Chem. Int. Ed. 52, 2688–2700 (2013).Kurmoo, M. Magnetic metal-organic frameworks. Chem. Soc. Rev. 38, 1353–1379 (2009).Horcajada, P. et al. Metal–organic frameworks in biomedicine. Chem. Rev. 112, 1232–1268 (2012).Liu, J. et al. Applications of metal-organic frameworks in heterogeneous supramolecular catalysis. Chem. Soc. Rev. 43, 6011–6061 (2014).Rowsell, J. L. C. & Yaghi, O. M. Metal–organic frameworks: a new class of porous materials. Micropor. Mesopor. Mat. 73, 3–14 (2004).Eubank, J. F. et al. The next chapter in MOF pillaring strategies: trigonal heterofunctional ligands to access targeted high-connected three dimensional nets, isoreticular platforms. J. Am. Chem. Soc. 133, 17532–17535 (2011).Rodenas, T. et al. Metal-organic framework nanosheets in polymer composite materials for gas separation. Nat. Mater. 14, 48–55 (2015).Chang, Z. et al. Rational construction of 3D pillared metal–organic frameworks: synthesis, structures, and hydrogen adsorption properties. Inorg. Chem. 50, 7555–7562 (2011).Cheetham, A. K., Rao, C. N. R. & Feller, R. K. Structural diversity and chemical trends in hybrid inorganic-organic framework materials. Chem. Commun. 4780–4795 (2006).Loiseau, T. et al. A rationale for the large breathing of the porous aluminum terephthalate (MIL-53) upon hydration. Chem. Eur. J. 10, 1373–1382 (2004).Senkovska, I. et al. New highly porous aluminium based metal-organic frameworks: Al(OH)(ndc) (ndc=2,6-naphthalene dicarboxylate) and Al (OH) (bpdc) (bpdc=4,4′-biphenyl dicarboxylate). Micropor. Mesopor. Mat. 122, 93–98 (2009).Klein, N. et al. Structural flexibility and intrinsic dynamics in the M2(2,6-ndc)2(dabco) (M=Ni, Cu, Co, Zn) metal-organic frameworks. J. Mater. Chem. 22, 10303–10312 (2012).Hoffmann, H. C. et al. High-pressure in situ 129Xe NMR spectroscopy and computer simulations of breathing transitions in the metal–organic framework Ni2(2,6-ndc)2(dabco) (DUT-8(Ni). J. Am. Chem. Soc. 133, 8681–8690 (2011).Gu, J.-M., Kim, W.-S. & Huh, S. Size-dependent catalysis by DABCO-functionalized Zn-MOF with one-dimensional channels. Dalton Trans. 40, 10826–10829 (2011).Carson, C. G. et al. Synthesis and structure characterization of copper terephthalate metal–organic frameworks. Eur. J. Inorg. Chem. 2009, 2338–2343 (2009).Yang, Q. et al. Probing the adsorption performance of the hybrid porous MIL-68(Al): a synergic combination of experimental and modelling tools. J. Mater. Chem. 22, 10210–10220 (2012).Li, H. et al. Visible light-driven water oxidation promoted by host-guest interaction between photosensitizer and catalyst with a high quantum efficiency. J. Am. Chem. Soc. 137, 4332–4335 (2015).Hapiot, F., Bricout, H., Menuel, S., Tilloy, S. & Monflier, E. Recent breakthroughs in aqueous cyclodextrin-assisted supramolecular catalysis. Catal. Sci. Technol. 4, 1899–1908 (2014).Harada, A., Takashima, Y. & Nakahata, M. Supramolecular polymeric materials via cyclodextrin-guest interactions. Acc. Chem. Res. 47, 2128–2140 (2014).Cong, H. et al. Substituent effect of substrates on cucurbit[8]uril-catalytic oxidation of aryl alcohols. J. Mol. Catal. A Chem. 374-375, 32–38 (2013).Masson, E., Ling, X., Joseph, R., Kyeremeh-Mensah, L. & Lu, X. Cucurbituril chemistry: a tale of supramolecular success. RSC Adv. 2, 1213–1247 (2012).Song, F.-T., Ouyang, G.-H., Li, Y., He, Y.-M. & Fan, Q.-H. Metallacrown ether catalysts containing phosphine-phosphite polyether ligands for Rh-catalyzed asymmetric hydrogenation—enhancements in activity and enantioselectivity. Eur. J. Org. Chem. 2014, 6713–6719 (2014).Rebilly, J.-N. & Reinaud, O. Calixarenes and resorcinarenes as scaffolds for supramolecular metallo-enzyme mimicry. Supramol. Chem. 26, 454–479 (2014).Ajami, D., Liu, L. & Rebek, J. Jr Soft templates in encapsulation complexes. Chem. Soc. Rev. 44, 490–499 (2015).Corma, A. & Garcia, H. Supramolecular host-guest systems in zeolites prepared by ship-in-a-bottle synthesis. Eur. J. Inorg. Chem. 2004, 1143–1164 (2004).Kemp, D. S., Cox, D. D. & Paul, K. G. Physical organic chemistry of benzisoxazoles. IV. Origins and catalytic nature of the solvent rate acceleration for the decarboxylation of 3-carboxybenzisoxazoles. J. Am. Chem. Soc. 97, 7312–7318 (1975).Thorn, S. N., Daniels, R. G., Auditor, M. T. & Hilvert, D. Large rate accelerations in antibody catalysis by strategic use of haptenic charge. Nature 373, 228–230 (1995).Yoshizawa, M., Klosterman, J. K. & Fujita, M. Functional molecular flasks: new properties and reactions within discrete, self-assembled hosts. Angew. Chem. Int. Ed. 48, 3418–3438 (2009).Yoshizawa, M., Tamura, M. & Fujita, M. Diels-Alder in aqueous molecular hosts: unusual regioselectivity and efficient catalysis. Science 312, 251–254 (2006).Murase, T., Nishijima, Y. & Fujita, M. Cage-catalyzed knoevenagel condensation under neutral conditions in water. J. Am. Chem. Soc. 134, 162–164 (2012).Zhao, C., Toste, F. D., Raymond, K. N. & Bergman, R. G. Nucleophilic substitution catalyzed by a supramolecular cavity proceeds with retention of absolute stereochemistry. J. Am. Chem. Soc. 136, 14409–14412 (2014).Choi, M. et al. Stable single-unit-cell nanosheets of zeolite MFI as active and long-lived catalysts. Nature 461, 246–249 (2009).Loiseau, T. et al. MIL-96, a porous aluminum trimesate 3D structure constructed from a hexagonal network of 18-membered rings and μ3-Oxo-centered trinuclear units. J. Am. Chem. Soc. 128, 10223–10230 (2006).Bezverkhyy, I. et al. MIL-53(Al) under reflux in water: formation of γ-AlO(OH) shell and H2BDC molecules intercalated into the pores. Micropor. Mesopor. Mat. 183, 156–161 (2014).Wang, L.-M. et al. Sodium stearate-catalyzed multicomponent reactions for efficient synthesis of spirooxindoles in aqueous micellar media. Tetrahedron 66, 339–343 (2010).List B. Science of Synthesis: Asymmetric Organocatalysis 1, Lewis Base and Acid Catalysts Georg Thieme Verlag (2012).He, T., Gu, Q. & Wu, X.-Y. Highly enantioselective Michael addition of isobutyraldehyde to nitroalkenes. Tetrahedron 66, 3195–3198 (2010).Avila, A., Chinchilla, R., Fiser, B., Gómez-Bengoa, E. & Nájera, C. Enantioselective Michael addition of isobutyraldehyde to nitroalkenes organocatalyzed by chiral primary amine-guanidines. Tetrahedron Asymmetry 25, 462–467 (2014).Meyer, B. & Peters, T. NMR spectroscopy techniques for screening and identifying ligand binding to protein receptors. Angew. Chem. Int. Ed. 42, 864–890 (2003).Szczygiel, A., Timmermans, L., Fritzinger, B. & Martins, J. C. Widening the view on dispersant−pigment interactions in colloidal dispersions with saturation transfer difference NMR spectroscopy. J. Am. Chem. Soc. 131, 17756–17758 (2009).Basilio, N., Martín-Pastor, M. & García-Río, L. Insights into the structure of the supramolecular amphiphile formed by a sulfonated calix[6]arene and alkyltrimethylammonium surfactants. Langmuir 28, 6561–6568 (2012).Mayer, M. & Meyer, B. Characterization of ligand binding by saturation transfer difference NMR spectroscopy. Angew. Chem. Int. Ed. 38, 1784–1788 (1999)

Ternary transition metals sulfides in hydrotreating catalysis.

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Ternary transition metals sulfides in hydrotreating catalysis

International audiencePure microcrystalline barium molybdate BaMoO4 and barium tungstate BaWO4 materials were prepared by molten flux reaction using alkali metal nitrates as reaction media. The obtained crystals have rhombic shape and expose mostly (111) crystallographic planes. Their mean size depends on the flux temperature and the nature of the alkali metal cation. Monomeric molybdate and tungstate used as precursors yield target products already at 673 K whereas if polymerized ammonium oxosalts were used, then higher temperatures were necessary to obtain barium salts. The optimal temperature for the preparation of pure crystals with well defined shape was found to be near 773 K. UV–visible spectra have been measured to precise energy gaps in these important d0 transition metal compounds. The values of Eg for these two mixed oxides are 4.3 eV for BaMoO4 and 3.8 eV for BaWO4. Such values contradict to what can be expected from the known data on their structure and the relative electronegativity of W and Mo ions. The possible xplanations of this observation are commented

Ternary transition metals sulfides in hydrotreating catalysis.

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Promotion of highly loaded MoS2/Al2O3 hydrodesulfurization catalysts prepared in aqueous solution

A procedure for the prepn. and promotion of highly loaded MoS2/Al2O3 catalysts (21 wt% Mo) obtained in aq. soln. by the redn. of (NH4)2MoS4 with N2H4 in the presence of Al2O3 was studied. Treating the freshly prepd. material with acetone results in the formation of carbon species (ca. 1 wt% C) that make it possible to maintain a high dispersion of the MoS2 particles. Several Co-promoted MoS2/Al2O3 catalysts were prepd. with different methods and Co precursors. Refluxing with Co(acac)2.2H2O dissolved in org. solvent proved to be the most efficient method for promoting highly loaded carbon-stabilized MoS2/Al2O3. The catalysts obtained can be used directly in the thiophene hydrodesulfurization reaction without any addnl. sulfidation, and they exhibit a much higher activity than a com. ref. catalyst. An EXAFS study revealed that the acetylacetonate precursor is decompd. during the refluxing treatment and gives new species in which Co is surrounded by sulfur instead of oxygen. The formation of a highly dispersed CoMoS phase was obsd. after further thiophene hydrodesulfurization reaction

Solution preparation of the amorphous molybdenum oxysulfide MoOS2 and its use for catalysis

Acid condensation of aq. MoO2S2-2 anion yields amorphous MoOS2 oxysulfide. This compd. possesses tubular morphol. and when freshly pptd. is sol. in polar orgs. such as acetone and ethanol. The ensemble of characterizations (IR, UV-visible, EXAFS spectroscopy) suggests that it contains cyclic or short linear oligomers of neutral molybdenum (V) oxysulfide MoOS2 core. Thermal decompn. of MoOS2 under inert atm. leads to the formation of a mixt. of MoO2 and MoS2 phases. Promotion of MoOS2 with cobalt followed by sulfidation leads to highly active HDS catalysts

Ultrasound assisted synthesis in aqueous media of nano MoS2,and its promotion with Co

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Sonochemical Preparation of MoS2 in Aqueous Solution: Replication of the Cavitation Bubbles in an Inorganic Material Morphology

Highly dispersed MoS2 was obtained by sonolysis of a simple inorg. Mo precursor in aq. soln. CH3COSH was added to (NH4)6Mo7O24.4H2O aq. soln. and the mixt. was irradiated for 1 h at room temp. with high intensity ultrasound. Sulfiding agent was hydrogen sulfide generated in situ from the sonication of thiolacetic acid. After filtering and water-washing the mixt., the resulting ppt. was heated at 400° in H2S/H2 gas mixt. for 4 h. The compn. and crystal structure of the material was detd., the catalytic activity evaluated for thiophene, and the surface area calcd

Ultrasound assisted synthesis, in aqueous media, of nanometric MoS2 and its promotion with Co.

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