Tuning the Catalytic Properties of UiO-66 Metal-Organic Frameworks: From Lewis to Defect-Induced Bronsted Acidity

[EN] The Lewis/Bronsted acidity and catalytic properties of UiO-66-type metal-organic frameworks are studied in the context of tunable acid catalysts based on the presence of linker defects that create coordinatively unsaturated Zr4+ centers. Fourier transform infrared spectroscopy of adsorbed CO and direct pH measurements are employed to characterize hydrated and dehydrated UiO-66 containing different number of Zr4+ sites associated with defects. These sites can strongly polarize coordinated water molecules, which induces Bronsted acidity in the hydrated material. Upon dehydration of the solid, the coordinated water molecules are removed, and the underlying coordinatively unsaturated Zr4+ cations become exposed and available as Lewis acid sites. Herein we show, for various acid-catalyzed reactions, how it is possible to shift from a Bronsted acid to a Lewis acid catalyst by simply controlling the hydration degree of the solid. This control adds a new dimension to the design and engineering of MOFs for catalytic applicationsFinancial support by the Spanish Government is acknowledged through projects MAT2017-82288-C2-1-P and the Severo Ochoa program (SEV-2016-0683)Cirujano, FG.; Llabrés I Xamena, FX. (2020). Tuning the Catalytic Properties of UiO-66 Metal-Organic Frameworks: From Lewis to Defect-Induced Bronsted Acidity. The Journal of Physical Chemistry Letters. 11(12):4879-4890. https://doi.org/10.1021/acs.jpclett.0c00984S48794890111

Visible-Light-Driven Photocatalytic Coupling of Benzylamine over Titanium-Based MIL-125-NH2 Metal-Organic Framework: A Mechanistic Study

This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.jpcc.0c06950.[EN] Imines are important building blocks in organic chemistry. Titanium-based metal-organic framework (MOF) MIL-125-NH2(Ti) can photocatalyze, under visible light and at room temperature, the selective aerobic oxidation of benzylamine to N-benzylidenebenzylamine. We investigated the reaction mechanism using catalytic tests, ex situ infrared spectroscopy, and density functional calculations. In the dark, the presence of MIL-125-NH2(Ti) alone does not improve the reaction yield with respect to a blank experiment. This poor catalytic performance in the dark is associated with the absence of polarizing species on the MOF surface, as confirmed by acetonitrile adsorption. Excitation with different spectral regions evidenced the determinant role of the 450 < lambda < 385 nm range for catalyst photoactivation. The calculations show that the last step of the reaction would have an energy barrier of 206 kJ mol(-1) in anhydrous conditions, while it decreases to 88 kJ mol(-1) only if the mechanism is mediated by two water molecules.Financial support by the Spanish Government is acknowledged through projects MAT2017-82288-C2-1-P and the Severo Ochoa program (SEV-2016-0683). We further thank Bartolomeo Civalleri for the kind help with the calculations and Diego Pellerej for experimental assistance.Vitillo, JG.; Presti, D.; Luz, I.; Llabrés I Xamena, FX.; Bordiga, S. (2020). Visible-Light-Driven Photocatalytic Coupling of Benzylamine over Titanium-Based MIL-125-NH2 Metal-Organic Framework: A Mechanistic Study. The Journal of Physical Chemistry C. 124(43):23707-23715. https://doi.org/10.1021/acs.jpcc.0c06950S23707237151244

Catalytic properties of pristine and defect-engineered Zr-MOF-808 metal organic frameworks

[EN] Various defect-engineered Zr-trimesate MOF-808 compounds (DE-MOF-808) have been prepared by mixing the tricarboxylate ligands with dicarboxylate ligands; viz. isophthalate, pyridine-3,5-dicarboxylate, 5-hydroxy-isophthalate, or 5-amino-isophthalate. The resulting mixed-ligand compounds, MOF-808-X (X = IP, Pydc, OH or NH2) were all found to be highly crystalline and isostructural to the unmodified MOF-808. Pristine MOF-808 showed better catalytic performance than a UiO-66 reference compound for the Meerwein-Ponndorf-Verley (MPV) reduction of carbonyl compounds. This was attributed to a higher availability of coordinatively unsaturated Zr4+ sites (cus) in MOF-808 upon removal of formate ions. Meanwhile, cus in UiO-66 are only located at defect sites and are thus much less abundant. Further improvement of the catalytic activity of defect-engineered MOF-808-IP and MOF-808-Pydc was observed, which may be related with the occurrence of less crowded Zr4+ sites in DE-MOF-808. The wider pore structure of MOF-808 with respect to UiO-66 compounds translates into a sharp improvement of the activity for the MPV reduction of bulky substrates, as shown for estrone reduction to estradiol. Interestingly, MOF-808 produces a notable diastereoselectivity towards the elusive 17--hydroxy estradiol.This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 641887 (project acronym: DEFNET). Financial support from the Spanish Ministry of Economy and Competitiveness (program Severo Ochoa SEV20120267), the Spanish Ministry of Science and Innovation (project MAT2014-52085-C2-1-P), and the German Research Foundation (project KA 1698/19-1) is also gratefully acknowledged. The Microscopy Service of the Universitat Politecnica de Valencia are gratefully acknowledged for the SEM images.Mautschke, H.; Drache, F.; Senkovska, I.; Kaskel, S.; Llabrés I Xamena, FX. (2018). Catalytic properties of pristine and defect-engineered Zr-MOF-808 metal organic frameworks. Catalysis Science & Technology. 8(14):3610-3616. https://doi.org/10.1039/c8cy00742jS3610361681

MOFs as multifunctional catalysts: One-pot synthesis of menthol from citronellal over a bifunctional MIL-101 catalyst

A bifunctional MOF catalyst containing coordinatively unsaturated Cr3+ sites and palladium nanoparticles (Pd@MIL-101) has been used for the cyclization of citronellal to isopulegol and for the one-pot tandem isomerization/hydrogenation of citronellal to menthol. The MOF was found to be stable under the reaction conditions used, and the results obtained indicate that the performance of this bifunctional solid catalyst is comparable with other state-of-the-art materials for the tandem reaction: Full citronellal conversion was attained over Pd@MIL-101 in 18 h, with 86% selectivity to menthols and a diastereoselectivity of 81% to the desired (-)-menthol, while up to 30 h were necessary for attaining similar values over Ir/H-beta under analogous reaction conditions.Financial support by Ministerio de Educacion y Ciencia e Innovacion (Project MIYCIN, CSD2009-00050; PROGRAMA CONSOLIDER. INGENIO 2009), Generalidad Valenciana (GV PROMETEO/2008/130) and the CSIC (Proyectos Intramurales Especiales 201080I020) is gratefully acknowledged.García Cirujano, F.; Llabrés I Xamena, FX.; Corma Canós, A. (2012). MOFs as multifunctional catalysts: One-pot synthesis of menthol from citronellal over a bifunctional MIL-101 catalyst. Dalton Transactions. 41:4249-4254. https://doi.org/10.1039/c2dt12480gS4249425441Corma, A., García, H., & Llabrés i Xamena, F. X. (2010). Engineering Metal Organic Frameworks for Heterogeneous Catalysis. Chemical Reviews, 110(8), 4606-4655. doi:10.1021/cr9003924Farrusseng, D., Aguado, S., & Pinel, C. (2009). Metal-Organic Frameworks: Opportunities for Catalysis. Angewandte Chemie International Edition, 48(41), 7502-7513. doi:10.1002/anie.200806063Lee, J., Farha, O. K., Roberts, J., Scheidt, K. A., Nguyen, S. T., & Hupp, J. T. (2009). Metal–organic framework materials as catalysts. Chemical Society Reviews, 38(5), 1450. doi:10.1039/b807080fWang, Z., & Cohen, S. M. (2009). Postsynthetic modification of metal–organic frameworks. Chemical Society Reviews, 38(5), 1315. doi:10.1039/b802258pBanerjee, M., Das, S., Yoon, M., Choi, H. J., Hyun, M. H., Park, S. M., … Kim, K. (2009). Postsynthetic Modification Switches an Achiral Framework to Catalytically Active Homochiral Metal−Organic Porous Materials. Journal of the American Chemical Society, 131(22), 7524-7525. doi:10.1021/ja901440gGASCON, J., AKTAY, U., HERNANDEZALONSO, M., VANKLINK, G., & KAPTEIJN, F. (2009). Amino-based metal-organic frameworks as stable, highly active basic catalysts. Journal of Catalysis, 261(1), 75-87. doi:10.1016/j.jcat.2008.11.010Hasegawa, S., Horike, S., Matsuda, R., Furukawa, S., Mochizuki, K., Kinoshita, Y., & Kitagawa, S. (2007). Three-Dimensional Porous Coordination Polymer Functionalized with Amide Groups Based on Tridentate Ligand:  Selective Sorption and Catalysis. Journal of the American Chemical Society, 129(9), 2607-2614. doi:10.1021/ja067374yCho, S.-H., Ma, B., Nguyen, S. T., Hupp, J. T., & Albrecht-Schmitt, T. E. (2006). A metal–organic framework material that functions as an enantioselective catalyst for olefin epoxidation. Chem. Commun., (24), 2563-2565. doi:10.1039/b600408cZhang, X., Llabrés i Xamena, F. X., & Corma, A. (2009). Gold(III) – metal organic framework bridges the gap between homogeneous and heterogeneous gold catalysts. Journal of Catalysis, 265(2), 155-160. doi:10.1016/j.jcat.2009.04.021Meilikhov, M., Yusenko, K., Esken, D., Turner, S., Van Tendeloo, G., & Fischer, R. A. (2010). Metals@MOFs - Loading MOFs with Metal Nanoparticles for Hybrid Functions. European Journal of Inorganic Chemistry, 2010(24), 3701-3714. doi:10.1002/ejic.201000473Henschel, A., Gedrich, K., Kraehnert, R., & Kaskel, S. (2008). Catalytic properties of MIL-101. Chemical Communications, (35), 4192. doi:10.1039/b718371bVermoortele, F., Ameloot, R., Vimont, A., Serre, C., & De Vos, D. (2011). An amino-modified Zr-terephthalate metal–organic framework as an acid–base catalyst for cross-aldol condensation. Chem. Commun., 47(5), 1521-1523. doi:10.1039/c0cc03038dWu, P., Wang, J., Li, Y., He, C., Xie, Z., & Duan, C. (2011). Luminescent Sensing and Catalytic Performances of a Multifunctional Lanthanide-Organic Framework Comprising a Triphenylamine Moiety. Advanced Functional Materials, 21(14), 2788-2794. doi:10.1002/adfm.201100115Pan, Y., Yuan, B., Li, Y., & He, D. (2010). Multifunctional catalysis by Pd@MIL-101: one-step synthesis of methyl isobutyl ketone over palladium nanoparticles deposited on a metal–organic framework. Chemical Communications, 46(13), 2280. doi:10.1039/b922061eCliment, M. J., Corma, A., Guil-López, R., Iborra, S., & Primo, J. (1998). Use of Mesoporous MCM-41 Aluminosilicates as Catalysts in the Preparation of Fine Chemicals. Journal of Catalysis, 175(1), 70-79. doi:10.1006/jcat.1998.1970Climent, M. J., Corma, A., Iborra, S., & Velty, A. (2002). Designing the adequate base solid catalyst with Lewis or Bronsted basic sites or with acid–base pairs. Journal of Molecular Catalysis A: Chemical, 182-183, 327-342. doi:10.1016/s1381-1169(01)00501-5Boronat, M., Climent, M. J., Corma, A., Iborra, S., Montón, R., & Sabater, M. J. (2010). Bifunctional Acid-Base Ionic Liquid Organocatalysts with a Controlled Distance Between Acid and Base Sites. Chemistry - A European Journal, 16(4), 1221-1231. doi:10.1002/chem.200901519Corma, A., Díaz, U., García, T., Sastre, G., & Velty, A. (2010). Multifunctional Hybrid Organic−Inorganic Catalytic Materials with a Hierarchical System of Well-Defined Micro- and Mesopores. Journal of the American Chemical Society, 132(42), 15011-15021. doi:10.1021/ja106272zFerey, G. (2005). A Chromium Terephthalate-Based Solid with Unusually Large Pore Volumes and Surface Area. Science, 309(5743), 2040-2042. doi:10.1126/science.1116275Corma, A., & Renz, M. (2004). Sn-Beta zeolite as diastereoselective water-resistant heterogeneous Lewis-acid catalyst for carbon–carbon bond formation in the intramolecular carbonyl–ene reaction. Chem. Commun., (5), 550-551. doi:10.1039/b313738dIosif, F., Coman, S., Pârvulescu, V., Grange, P., Delsarte, S., Vos, D. D., & Jacobs, P. (2004). Ir-Beta zeolite as a heterogeneous catalyst for the one-pot transformation of citronellal to menthol. Chem. Commun., (11), 1292-1293. doi:10.1039/b403692aNeaţu, F., Coman, S., Pârvulescu, V. I., Poncelet, G., De Vos, D., & Jacobs, P. (2009). Heterogeneous Catalytic Transformation of Citronellal to Menthol in a Single Step on Ir-Beta Zeolite Catalysts. Topics in Catalysis, 52(9), 1292-1300. doi:10.1007/s11244-009-9270-9MERTENS, P., VERPOORT, F., PARVULESCU, A., & DEVOS, D. (2006). Pt/H-beta zeolites as productive bifunctional catalysts for the one-step citronellal-to-menthol conversion. Journal of Catalysis, 243(1), 7-13. doi:10.1016/j.jcat.2006.06.017Da Silva Rocha, K. A., Robles-Dutenhefner, P. A., Sousa, E. M. B., Kozhevnikova, E. F., Kozhevnikov, I. V., & Gusevskaya, E. V. (2007). Pd–heteropoly acid as a bifunctional heterogeneous catalyst for one-pot conversion of citronellal to menthol. Applied Catalysis A: General, 317(2), 171-174. doi:10.1016/j.apcata.2006.10.019Trasarti, A. F., Marchi, A. J., & Apesteguı́a, C. R. (2004). Highly selective synthesis of menthols from citral in a one-step process. Journal of Catalysis, 224(2), 484-488. doi:10.1016/j.jcat.2004.03.016TRASARTI, A., MARCHI, A., & APESTEGUIA, C. (2007). Design of catalyst systems for the one-pot synthesis of menthols from citral. Journal of Catalysis, 247(2), 155-165. doi:10.1016/j.jcat.2007.01.016Alaerts, L., Séguin, E., Poelman, H., Thibault-Starzyk, F., Jacobs, P. A., & De Vos, D. E. (2006). Probing the Lewis Acidity and Catalytic Activity of the Metal–Organic Framework [Cu3(btc)2] (BTC=Benzene-1,3,5-tricarboxylate). Chemistry - A European Journal, 12(28), 7353-7363. doi:10.1002/chem.200600220Horcajada, P., Surblé, S., Serre, C., Hong, D.-Y., Seo, Y.-K., Chang, J.-S., … Férey, G. (2007). Synthesis and catalytic properties of MIL-100(Fe), an iron(iii) carboxylate with large pores. Chem. Commun., (27), 2820-2822. doi:10.1039/b704325bRavon, U., Chaplais, G., Chizallet, C., Seyyedi, B., Bonino, F., Bordiga, S., … Farrusseng, D. (2010). Investigation of Acid Centers in MIL-53(Al, Ga) for Brønsted-Type Catalysis: In Situ FTIR and Ab Initio Molecular Modeling. ChemCatChem, 2(10), 1235-1238. doi:10.1002/cctc.201000055Vimont, A., Leclerc, H., Maugé, F., Daturi, M., Lavalley, J.-C., Surblé, S., … Férey, G. (2007). Creation of Controlled Brønsted Acidity on a Zeotypic Mesoporous Chromium(III) Carboxylate by Grafting Water and Alcohol Molecules. The Journal of Physical Chemistry C, 111(1), 383-388. doi:10.1021/jp064686

Photodegradation of Phenol over a Hybrid Organo-Inorganic Material: Iron(II) Hydroxyphosphonoacetate

Water treatment is a hot topic, and it will become much more important in the decades ahead. Advanced oxidation processes are being increasingly used for organic contaminant removal, for example using photo-Fenton reactions. Here we report the use of an organo-inorganic hybrid, Fe[HO3PCH(OH)COO]·2H2O, as Fenton photocatalyst for phenol oxidation with H2O2 under UVA radiation. Preactivation, catalyst content, and particle size parameters have been studied/optimized for increasing phenol mineralization. Upon reaction, iron species are leached from the catalyst making a homogeneous catalysis contribution to the overall phenol photo-oxidation. Under optimized conditions, the mineralization degree was slightly larger than 90% after 80 min of irradiation. Analysis by X-ray photoelectron spectroscopy revealed important chemical modifications occurring on the surface of the catalyst after activation and phenol photodegradation. The sustained slow delivery of iron species upon phenol photoreaction is advantageous as the mixed heterogeneous−homogeneous catalytic processes result in very high phenol mineralization.Proyecto nacional MAT2010-1517

Metal organic framework nanosheets in polymer composite materials for gas separation

[EN] Composites incorporating two-dimensional nanostructures within polymeric matrices have potential as functional components for several technologies, including gas separation. Prospectively, employing metal-organic frameworks (MOFs) as versatile nanofillers would notably broaden the scope of functionalities. However, synthesizing MOFs in the form of freestanding nanosheets has proved challenging. We present a bottom-up synthesis strategy for dispersible copper 1,4-benzenedicarboxylate MOF lamellae of micrometre lateral dimensions and nanometre thickness. Incorporating MOF nanosheets into polymer matrices endows the resultant composites with outstanding CO2 separation performance from CO2/CH4 gas mixtures, together with an unusual and highly desired increase in the separation selectivity with pressure. As revealed by tomographic focused ion beam scanning electron microscopy, the unique separation behaviour stems from a superior occupation of the membrane cross-section by the MOF nanosheets as compared with isotropic crystals, which improves the efficiency of molecular discrimination and eliminates unselective permeation pathways. This approach opens the door to ultrathin MOF-polymer composites for various applications.The research leading to these results has received funding (J.G., B.S.) from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement no. 335746, CrystEng-MOF-MMM. T.R. is grateful to TUDelft for funding. G.P. acknowledges the A. von Humboldt Foundation for a research grant. A.C., I.L. and F.X.L.i.X. thank Consolider-Ingenio 2010 (project MULTICAT) and the ‘Severo Ochoa’ programme for support. 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Ethane/ethene separation turned on its head: Selective ethane adsorption on the metal-organic framework ZIF-7 through a gate-opening mechanism. J. Am. Chem. Soc. 132, 17704–17706 (2010).Deng, H. et al. Multiple functional groups of varying ratios in metal-organic frameworks. Science 12, 846–850 (2010).Khaletskaya, K. et al. Integration of porous coordination polymers and gold nanorods into core-shell mesoscopic composites toward light-induced molecular release. J. Am. Chem. Soc. 135, 10998–11005 (2013).Corma, A., Garcia, H. & Llabrés i Xamena, F. X. Engineering metal organic frameworks for heterogeneous catalysis. Chem. Rev. 110, 4606–4655 (2010).Mueller, U. et al. Metal-organic frameworks-prospective industrial applications. J. Mater. Chem. 16, 626–636 (2006).Gascon, J. & Kapteijn, F. Metal-organic framework membranes-high potential, bright future? Angew. Chem. Int. Ed. 49, 1530–1532 (2010).Li, Y. S. et al. 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Water and Metal-Organic Frameworks: From Interaction toward Utilization

The steep stepwise uptake of water vapor and easy release at low relative pressures and moderate temperatures together with high working capacities make metal-organic frameworks (MOFs) attractive, promising materials for energy efficient applications in adsorption devices for humidity control (evaporation and condensation processes) and heat reallocation (heating and cooling) by utilizing water as benign sorptive and low-grade renewable or waste heat. Emerging MOF-based process applications covered are desiccation, heat pumps/chillers, water harvesting, air conditioning, and desalination. Governing parameters of the intrinsic sorption properties and stability under humid conditions and cyclic operation are identified. Transport of mass and heat in MOF structures, at least as important, is still an underexposed topic. Essential engineering elements of operation and implementation are presented. An update on stability of MOFs in water vapor and liquid systems is provided, and a suite of 18 MOFs are identified for selective use in heat pumps and chillers, while several can be used for air conditioning, water harvesting, and desalination. Most applications with MOFs are still in an exploratory state. An outlook is given for further R&amp;D to realize these applications, providing essential kinetic parameters, performing smart engineering in the design of systems, and conceptual process designs to benchmark them against existing technologies. A concerted effort bridging chemistry, materials science, and engineering is required. ©ChemE/Catalysis Engineerin