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

Unexpected photochemistry and charge-transfer complexes of [CB11H12]2 carborane

Although the [CB11H12]¯carborane does not exhibit an absorption band inUV, its triplet excited state can be generated upon 308 nm laser excitation; also unexpectedly carborane acts as electron donor forming a charge transfer complex with methylviologen that upon illumination gives rise to viologen radical cation.Galletero Pedroche, M.Sales, [email protected]

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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Predictive models for mixed-matrix membrane performance: A review. Chem. Rev. 113, 4980–5028 (2013)

Uso de compuestos metal-orgánicos para la reducción selectiva de cetosteroides

Se describe el uso de compuestos híbridos MetalOrgánicos (MOFs, de sus siglas en inglés MetaiOrganic Framework), como catalizadores heterogéneos para la reducción (quimio-, regio-y estereoselectiva) de compuestos tipo cetosteroides. El uso de estos materiales como catalizadores permite, en particular, preparar derivados de alto valor añadido difícilmente obtenibles con otros catalizadores (homogéneos, heterogéneos o biocatalizadores), o a través de rutas de síntesis orgánicas alternativas. Así por ejemplo, el uso de los compuestos metal-orgánicos descritos en esta patente permite transformar selectivamente estrona en estradiol, o trans-androsterona en androstandiol con elevada diastereoselectividad al correspondiente isómero 17a-OH; así como la ,.... reducción regio-y diastereoselectiva de androstendiona a epitestosterona.Peer reviewedConsejo Superior de Investigaciones Científicas (España), Universitat Politecnica de ValenciaA1 Solicitud de patente con informe sobre el estado de la técnic

MOF-808 as a Highly Active Catalyst for the Diastereoselective Reduction of Substituted Cyclohexanones

Zr-containing MOF-808 is an excellent heterogeneous catalyst for the diastereoselective Meerwein&ndash;Ponndorf&ndash;Verley reduction of substituted cyclohexanones. The presence of substituents at the 2 or 3 position of the cyclohexanone ring strongly drives the reaction towards the formation of one of the two possible isomers. For 3-methyl cyclohexanone, the available space inside the MOF pores allows the formation of the bulkier transition state leading to the thermodynamically stable 3-cis-cyclohexanol. For 2-methyl cyclohexanone, the reaction rate is much slower and the final diastereoselectivity depends on the size of the alcohol used. Finally, reduction of 2-phenyl cyclohexanone is considerable faster over MOF-808 than for any other catalyst reported so far. The large size of the phenyl favors the selective formation (up to 94% selectivity) of the cis-alcohol, which goes through a less hindered transition state

Zr-Containing UiO-66 Metal-Organic Frameworks as Highly Selective Heterogeneous Acid Catalysts for the Direct Ketalization of Levulinic Acid

Zr-containing UiO-66 materials are active and reusable heterogeneous catalysts for the selective ketalization of levulinic acid (LA) with 1,2-propanediol, affording selectivities of up to 91–93% at full LA conversion, with very low levels of ester or ketal–ester byproducts. This allows the preparation of the target ketal directly from LA and avoiding intermediate esterification steps of LA to levulinate esters to minimize the formation of unwanted side products. The catalytic activity of UiO-66 is found to depend critically on the hydration degree of the solid and the amount of missing linker defects. The most likely active sites for ketalization in (defective) UiO-66 are Brønsted-induced acid sites arising from the strong coordination and polarization of HO molecules onto accessible Zr associated with missing linker defects. A progressive deactivation is observed upon catalytic reuse, which is attributed to adsorbed reaction products poisoning the catalytic sites. These adsorbed products are easily removed by washing the spent catalyst with a dilute 2% HCl ethanolic solution, which completely restores the initial catalytic activity while maintaining the crystallinity of the solid intact.The authors are grateful for grant PID2020-112590GB-C21 funded by MCIN/AEI/10.13039/501100011033 and Grant MAT2017-82288-C2-1-P funded by MCIN/AEI and ERDF A way of making Europe

Sulfide organic polymers as novel and efficient metal-free heterogeneous Lewis acid catalysts for esterification reactions

Herein, we report on the synthesis of four organosulfide-based covalent organic polymers prepared via click processes, consisting of either S2 (SOP-1 and SOP-3) or thiol-yne (SOP-2 and SOP-4) coupling reactions. Formation of the SOPs in high yields is confirmed by solid-state C NMR and FTIR spectroscopies, while the sulfur contents of SOP-type materials confirm the expected C : S molar ratio for the formation of stoichiometric products. CO adsorption isotherms reveal the porosity of SOPs, with specific surface areas of up to 180 m g and strongly dependent on the ligands used. The catalytic activity of SOPs is evaluated for carboxylic acid esterification reactions, obtaining high conversions and efficient recyclability. The proposed reaction mechanism consists of the activation of carboxylic acid by hypervalent S⋯O (n → σ*) interactions with sulfur centres of the SOPs, which increase the electrophilic character of the carboxylic carbon and facilitate the addition of the alcohol. Thus, SOPs constitute a novel class of metal-free heterogeneous Lewis acid (organo)catalysts.Financial support from the Spanish Ministry of Science and Innovation (PID2020-112590GB-C21 and CEX2021-001230-S grants funded by MCIN/AEI/10.13039/501100011033) is gratefully acknowledged. This study forms part of the Advanced Materials Program and was supported by MICIN with funding from European Union NextGeneration (PRTR-C17.I1) and by the Generalitat Valenciana (MFA/2022/003). M. M. acknowledges financial support from FPI PhD fellowship PRE2018-084071

Acid-catalyzed diastereoselective reactions inside MOF pores

Grant PID2020-112590GB-C21 funded by MCIN/AEI/10.13039/501100011033. S.N. thanks the support of grant PID2021-123856OB-I00 funded byMCIN/AEI/10.13039/ 501100011033 and by ERDF A way of making Europ

Zr-containing UiO-66 metal-organic frameworks as efficient heterogeneous catalysts for glycerol valorization: synthesis of hyacinth and other glyceryl acetal fragrances

Zr-containing UiO-66 and UiO-66-NH are good heterogeneous catalysts for the acetalization of phenylacetaldehyde with glycerol, producing the corresponding hyacinth fragrance in high yields after short (2 h) reaction times. Mixtures of 1,3-dioxolanes and 1,3-dioxanes are obtained, whose ratios can be modified between 2.8 and 4.6 depending on the catalyst used, the amount of missing linker defects of the solid, and the reaction time. The catalysts are stable under the reaction conditions used, and they can be reused without loss of activity or selectivity. The scope of UiO-66 materials is demonstrated for the formation of other glyceryl acetals of interest for the flavoring industry, which represents an interesting route for glycerol valorization.The authors are grateful for grant PID2020-112590GB-C21 funded by MCIN/AEI/10.13039/50110001103