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[EN] In this work, a catalytic method is presented for the synthesis of aromatic carbamates from aromatic amines using dimethyl carbonate instead of phosgene as a green and safe reaction process. Microcrystalline Zr-MOF-808 is reported as an active and efficient heterogeneous catalyst for the selective carbamoylation of anilines and industrially relevant aromatic diamines, under mild reaction conditions with near quantitative yields. We have accomplished the selective growth of well-dispersed Zr-MOF-808 nanocrystals within the mesoporous material MCM-41. A superior catalytic performance of the Zr-MOF808@MCM-41 is demonstrated that together with increased stability stands out as an advantageous heterogeneous catalyst for polyurethane production. In situ FTIR studies have allowed a better understanding of the reaction pathway at the molecular level when the active MOF catalyst is present. ; This work was funded by the European Union through the European Research Council (grant ERC-AdG-2014-671093, SynCatMatch) and by the Spanish government through the Severo Ochoa program (SEV-2016-0683). S.R.-B. acknowledges a PhD fellowship from the Generalitat Valenciana. The Electron Microscopy Service of the Universitat Politecnica de Valenciais acknowledged for their help in sample characterization. ; Rojas-Buzo, S.; García-García, P.; Corma Canós, A. (2019). Zr-MOF-808@MCM-41 catalyzed phosgene-free synthesis of polyurethane precursors. Catalysis Science & Technology. 9(1):146-156. https://doi.org/10.1039/c8cy02235f ; S ; 146 ; 156 ; 9 ; 1 ; Tundo, P., & Selva, M. (2002). The Chemistry of Dimethyl Carbonate. Accounts of Chemical Research, 35(9), 706-716. doi:10.1021/ar010076f ; Fiorani, G., Perosa, A., & Selva, M. (2018). Dimethyl carbonate: a versatile reagent for a sustainable valorization of renewables. Green Chemistry, 20(2), 288-322. doi:10.1039/c7gc02118f ; Tundo, P., Rossi, L., & Loris, A. (2005). Dimethyl Carbonate as an Ambident Electrophile. The Journal of Organic Chemistry, 70(6), 2219-2224. ...

[EN] The modulated hydrothermal (MHT) synthesis of an active and selective Hf-MOF-808 material for the N-alkylation reaction of aniline with benzyl alcohol under base-free mild reaction conditions is reported. Through kinetic experiments and isotopically labeled NMR spectroscopy studies, we have demonstrated that the reaction mechanism occurs via borrowing hydrogen (BH) pathway, in which the alcohol dehydrogenation is the limiting step. The high concentration of defective -OH groups generated on the metallic nodes through MHT synthesis enhances the alcohol activation, while the unsaturated Hf4+, which acts as a Lewis acid site, is able to borrow the hydrogen from the methylene position of benzyl alcohol. This fact makes this material at least 14 times more active for the N-alkylation reaction than the material obtained via solvothermal synthesis. The methodology described in this work could be applied to a wide range of aniline and benzyl alcohol derivates, showing in all cases high selectivity toward the corresponding N-benzylaniline product. Finally, Hf-MOF-808, which acts as a true heterogeneous catalyst, can be reused in at least four consecutive runs without any activity loss. ; This work has been supported by Spanish Government through "severo Ochoa" (SEV-2016-0683, MINECO) and RTI2018-101033-B-I00 (MCIU/AEI/FEDER, UE). The Electron Microscopy Service of the UPV is also acknowledged for their help in sample characterization. ; Bohigues, B.; Rojas-Buzo, S.; Moliner Marin, M.; Corma Canós, A. (2021). Coordinatively Unsaturated Hf-MOF-808 Prepared via Hydrothermal Synthesis as a Bifunctional Catalyst for the Tandem N-Alkylation of Amines with Benzyl Alcohol. ACS Sustainable Chemistry & Engineering. 9(47):15793-15806. https://doi.org/10.1021/acssuschemeng.1c04903 ; S ; 15793 ; 15806 ; 9 ; 47

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Sustainable Chemistry & Engineering, 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/acssuschemeng.0c04398 ; [EN] The catalytic performance of two different MOFs, UiO-66 and MOF-808, containing Lewis acid active sites has been evaluated for the transformation of glucose in water and compared with that of analogous Lewis acid Zr-beta zeolite. While fructose is the main product obtained on Zr-beta, mannose production increases when using Zr-MOFs as catalysts. Kinetic studies reveal a lower activation energy barrier for glucose epimerization to mannose when using Zr-MOF catalysts (similar to 83-88 and similar to 100 kJ/mol for glucose epimerization and isomerization, respectively). A C-13 NMR study using (13)C1-labeled glucose allows confirming that on Zr-MOF catalysts, mannose is exclusively formed following the glucose epimerization route through a 1,2-intramolecular carbon shift, whereas the two-step glucose -> fructose -> mannose isomerization via 1,2-intramolecular proton shifts is the preferred pathway on Zr-beta. A computational study reveals a different mode of adsorption of deprotonated glucose on Zr-MOFs that allows decreasing the activation barrier for the 1,2-intramolecular carbon shift. The combination of spectroscopic, kinetic, and theoretical studies allows unraveling the nature of the metal sites in Zr-MOFs and Zr-beta catalysts and to propose a structure-activity relationship between the different Lewis acid sites and the glucose transformation reactions. The results presented here could permit new rationalized MOF catalyst designs with the specific active sites to facilitate particular reaction mechanisms. ; This work was supported by the Spanish Government through "Severo Ochoa"(SEV-2016-0683, MINECO), MAT2017-82288-C2-1-P (AEI/FEDER, UE), and RTI2018-101033-BI00 ...

[EN] In this work, we have studied the catalytic activity of different silicates (MFI, MCM-41, and Beta) containing Lewis acid sites (including Sn, Ti, Zr, and Hf) for the tandem N-alkylation reaction of aniline with benzyl alcohol. The Hf- and Zr-Beta were the most active catalysts for this transformation, showing in both cases selectivities toward the corresponding N-benzylaniline higher than 97%. FTIR and DFT analyses confirm that the active sites in the Hf-Beta catalyst for this process are the open sites where one of the four Hf-O bonds is hydrolyzed. Moreover, the amount of these active species could be notoriously increased with previous thermal treatment of the Lewis acid zeolite with benzyl alcohol. Isotopically labeled experiments and theoretical mechanistic studies reveal that the N-alkylation reaction occurs through a hydrogen borrowing pathway, in which in situ Hf-hydride species were generated. Finally, the Hf-Beta zeolite was reused several times in the N-alkylation reaction without any appreciable deactivation detected. This catalytic system could be expanded to a variety of amines, including aliphatic and biomass-derived amines. ; This work has been supported by the Spanish Government through "severo Ochoa" (SEV-2016-0683, MINECO), MAT2017-82288-C2-1-P (AEI/FEDER, UE), and RTI2018101033-B-I00 (MCIU/AEI/FEDER, UE). Dr. Susana Valencia is acknowledged for the preparation of the Ti-Beta sample. The Electron Microscopy Service of the UPV is also acknowledged for their help in sample characterization. Part of the computations were performed on the Tirant III cluster of the Servei d'Informa`tica of the University of Valencia. ; Rojas-Buzo, S.; Concepción Heydorn, P.; Corma Canós, A.; Moliner Marin, M.; Boronat Zaragoza, M. (2021). In-Situ-Generated Active Hf-hydride in Zeolites for the Tandem N-Alkylation of Amines with Benzyl Alcohol. ACS Catalysis. 11(13):8049-8061. https://doi.org/10.1021/acscatal.1c01739 ; S ; 8049 ; 8061 ; 11 ; 13

[EN] The structure of UiO-66(Ce) is formed by CeO2-x defective nanoclusters connected by terephthalate ligands. The initial presence of accessible Ce3+ sites in the as-synthesized UiO-66(Ce) has been determined by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR)-CO analyses. Moreover, linear scan voltammetric measurements reveal a reversible Ce4+/Ce3+ interconversion within the UiO-66(Ce) material, while nanocrystalline ceria shows an irreversible voltammetric response. This suggests that terephthalic acid ligands facilitate charge transfer between subnanometric metallic nodes, explaining the higher oxidase-like activity of UiO-66(Ce) compared to nanoceria for the mild oxidation of organic dyes under aerobic conditions. Based on these results, we propose the use of Ce-based metal-organic frameworks (MOFs) as efficient catalysts for the halogenation of activated arenes, as 1,3,5-trimethoxybenzene (TMB), using oxygen as a green oxidant. Kinetic studies demonstrate that UiO-66(Ce) is at least three times more active than nanoceria under the same reaction conditions. In addition, the UiO-66(Ce) catalyst shows an excellent stability and can be reused after proper washing treatments. Finally, a general mechanism for the oxidative halogenation reaction is proposed when using Ce-MOF as a catalyst, which mimics the mechanistic pathway described for metalloenzymes. The superb control in the generation of subnanometric CeO2-x defective clusters connected by adequate organic ligands in MOFs offers exciting opportunities in the design of Ce-based redox catalysts. ; This work has been supported by the Spanish Government through the "Severo Ochoa" (SEV-2016-0683, MINECO) and RTI2018-101033-B-I00 (MCIU/AEI/FEDER, UE). J. M. Salas is acknowledged for his contribution to CO-IR experiments. The Electron Microscopy Service of the UPV is also acknowledged for their help in sample characterization. ; Rojas-Buzo, S.; Concepción Heydorn, P.; Olloqui-Sariego, JL.; Moliner Marin, M.; Corma Canós, A. (2021). ...

The Lewis/Brønsted catalytic properties of the Metal-Organic Framework (MOF) nodes can be tuned by simply controlling the solvent employed in the synthetic procedure. In this work, we demonstrate that Hf-MOF-808 can be prepared from a material with a higher amount of Brønsted acid sites,viamodulated hydrothermal synthesis, to a material with a higher proportion of unsaturated Hf Lewis acid sites,viamodulated solvothermal synthesis. The Lewis/Brønsted acid properties of the resultant metallic clusters have been studied by different characterization techniques, including XAS, FTIR and NMR spectroscopies, combined with a DFT study. The different nature of the Hf-MOF-808 materials allows their application as selective catalysts in different target reactions requiring Lewis, Brønsted or Lewis-Brønsted acid pairs. ; This work has been supported by the Spanish Government through the "Severo Ochoa" (SEV-2016-0683, MINECO), MAT2017-82288-C2-1-P (AEI/FEDER, UE) and RTI2018-101033-B-I00 (MCIU/AEI/FEDER, UE). J. M. Salas is acknowledged for his contribution to CD3CN-FTIR experiments. C. W. L. thanks the PRH 50.1 – ANP/FINEP Human Resources Program for the Visiting Researcher Fellowship. This research used resources of the Advanced Photon Source, a user facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, and was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357 and by the Canadian Light Source and its funding partners. The Electron Microscopy Service of the UPV is also acknowledged for their help in sample characterization.

[EN] The Lewis/Bronsted catalytic properties of the Metal-Organic Framework (MOF) nodes can be tuned by simply controlling the solvent employed in the synthetic procedure. In this work, we demonstrate that Hf-MOF-808 can be prepared from a material with a higher amount of Bronsted acid sites, via modulated hydrothermal synthesis, to a material with a higher proportion of unsaturated Hf Lewis acid sites, via modulated solvothermal synthesis. The Lewis/Bronsted acid properties of the resultant metallic clusters have been studied by different characterization techniques, including XAS, FTIR and NMR spectroscopies, combined with a DFT study. The different nature of the Hf-MOF-808 materials allows their application as selective catalysts in different target reactions requiring Lewis, Bronsted or Lewis-Bronsted acid pairs. ; This work has been supported by the Spanish Government through the "Severo Ochoa" (SEV-2016-0683, MINECO), MAT2017-82288-C2-1-P (AEI/FEDER, UE) and RTI2018-101033-B-I00 (MCIU/AEI/FEDER, UE). J. M. Salas is acknowledged for his contribution to CD INF>3 /INF>CN-FTIR experiments. C. W. L. thanks the PRH 50.1 - ANP/FINEP Human Resources Program for the Visiting Researcher Fellowship. This research used resources of the Advanced Photon Source, a user facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, and was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357 and by the Canadian Light Source and its funding partners. The Electron Microscopy Service of the UPV is also acknowledged for their help in sample characterization. ; Rojas-Buzo, S.; Bohigues, B.; Lopes, CW.; Meira, DM.; Boronat Zaragoza, M.; Moliner Marin, M.; Corma Canós, A. (2021). Tailoring Lewis/Bronsted acid properties of MOF nodes via hydrothermal and solvothermal synthesis: simple approach with exceptional catalytic implications. Chemical Science. 12(29):10106-10115. https://doi.org/10.1039/d1sc02833b ; S ; 10106 ; 10115 ; 12 ; 29

[EN] Modulating the structures of subnanometric metal clusters at the atomic level is a great synthetic and characterization challenge in catalysis. Here, we show how the catalytic properties of subnanometric platinum clusters (0.5-0.6 nm) confined in the sinusoidal 10R channels of purely siliceous MFI zeolite are modulated upon introduction of partially reduced tin species that interact with the noble metal at the metal/support interface. The platinum-tin clusters are stable in H(2)over an extended period of time (>6 h), even at high temperatures (for example, 600 degrees C), which is determined by only a few additional tin atoms added to the platinum clusters. The structural features of platinum-tin clusters, which are not immediately visible by conventional characterization techniques but can be established after combination of in situ extended X-ray absorption fine structure, high-angle annular dark-field scanning transmission electron microscopy and CO infrared data, are key to providing a one-order of magnitude lower deactivation rate in the propane dehydrogenation reaction while maintaining high intrinsic (initial) catalytic activity ; This work was supported by the European Union through the European Research Council (grant ERC-AdG-2014-671093, SynCatMatch) and the Spanish government through the "Severo Ochoa Program" (SEV-2016-0683). L.L. thanks the ITQ for providing a contract. The authors also thank the Microscopy Service of the UPV for the TEM and STEM measurements. The XAS measurements were carried out in the CLAESS beamline of the ALBA synchrotron. We thank Giovanni Agostini for his kind support in the analysis of XAS data. HR-HAADF-STEM measurements were performed at DME-UCA at Cadiz University with financial support from FEDER/MINECO (MAT2017-87579-R and MAT2016-81118-P). C.W.L. thanks CAPES (Science without Frontiers -Process no. 13191/13-6) for a predoctoral fellowship. The financial support from ExxonMobil for this project is also greatly acknowledged. ; Liu, L.; Lopez-Haro, M.; Lopes, CW.; ...

628 638 3 8 ; S ; [EN] Modulating the structures of subnanometric metal clusters at the atomic level is a great synthetic and characterization challenge in catalysis. Here, we show how the catalytic properties of subnanometric platinum clusters (0.5-0.6 nm) confined in the sinusoidal 10R channels of purely siliceous MFI zeolite are modulated upon introduction of partially reduced tin species that interact with the noble metal at the metal/support interface. The platinum-tin clusters are stable in H(2)over an extended period of time (>6 h), even at high temperatures (for example, 600 degrees C), which is determined by only a few additional tin atoms added to the platinum clusters. The structural features of platinum-tin clusters, which are not immediately visible by conventional characterization techniques but can be established after combination of in situ extended X-ray absorption fine structure, high-angle annular dark-field scanning transmission electron microscopy and CO infrared data, are key to providing a one-order of magnitude lower deactivation rate in the propane dehydrogenation reaction while maintaining high intrinsic (initial) catalytic activity This work was supported by the European Union through the European Research Council (grant ERC-AdG-2014-671093, SynCatMatch) and the Spanish government through the "Severo Ochoa Program" (SEV-2016-0683). L.L. thanks the ITQ for providing a contract. The authors also thank the Microscopy Service of the UPV for the TEM and STEM measurements. The XAS measurements were carried out in the CLAESS beamline of the ALBA synchrotron. We thank Giovanni Agostini for his kind support in the analysis of XAS data. HR-HAADF-STEM measurements were performed at DME-UCA at Cadiz University with financial support from FEDER/MINECO (MAT2017-87579-R and MAT2016-81118-P). C.W.L. thanks CAPES (Science without Frontiers -Process no. 13191/13-6) for a predoctoral fellowship. The financial support from ExxonMobil for this project is also greatly acknowledged. Liu, L.; Lopez-Haro, ...