Predicting the DNP-SENS efficiency in reactive heterogeneous catalysts from hydrophilicity
| Autor: | Anne Lesage, Lyndon Emsley, Andrei Gurinov, Walid Almaksoud, Jean-Marie Basset, Baptiste Scotto, Luigi Cavallo, Anissa Bendjeriou-Sedjerari, Zhen Cao, Edy Abou-Hamad, Jasmine Viger-Gravel, Manoja K. Samantaray, David Gajan, Eva Pump |
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| Přispěvatelé: | KAUST Catalysis Center (KCC), King Abdullah University of Sciences & Technologie, Ecole Polytechnique Fédérale de Lausanne (EPFL), Solid-State NMR Methods for Materials - Méthodes de RMN à l'état solide pour les matériaux, Institut des Sciences Analytiques (ISA), Institut de Chimie du CNRS (INC)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), KAUST Core Lab, King Abdullah University of Science and Technology (KAUST), This work received support from the King Abdullah University of Science and Technology (KAUST) and the European Research Council (ERC Advanced Grant No. 320860)., European Project: 320860,EC:FP7:ERC,ERC-2012-ADG_20120216,HI-SENS(2013), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS) |
| Předmět: |
010405 organic chemistry
chemistry.chemical_element Nanoparticle Sorption General Chemistry Nuclear magnetic resonance spectroscopy 010402 general chemistry Photochemistry 01 natural sciences Nitrogen 0104 chemical sciences Catalysis Molecular level chemistry [CHIM]Chemical Sciences Polarization (electrochemistry) Carbon |
| Zdroj: | Chemical Science Chemical Science, The Royal Society of Chemistry, 2018, 9 (21), pp.4866-4872. ⟨10.1039/c8sc00532j⟩ Chemical Science, 2018, 9 (21), pp.4866-4872. ⟨10.1039/c8sc00532j⟩ |
| ISSN: | 2041-6520 2041-6539 |
| DOI: | 10.1039/c8sc00532j⟩ |
| Popis: | We thank Dr Olivier Ouari and Paul Tordo of the University of Aix-Marseille for providing the TEKPol radical.; International audience; Identification of surfaces at the molecular level has benefited from progress in dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP SENS). However, the technique is limited when using highly sensitive heterogeneous catalysts due to secondary reaction of surface organometallic fragments (SOMFs) with stable radical polarization agents. Here, we observe that in non-porous silica nanoparticles (NPs) (d(particle) = 15 nm) some DNP enhanced NMR or SENS characterizations are possible, depending on the metal-loading of the SOMF and the type of SOMF substituents (methyl, isobutyl, neopentyl). This unexpected observation suggests that aggregation of the nanoparticles occurs in non-polar solvents (such as ortho-dichlorobenzene) leading to (partial) protection of the SOMF inside the interparticle space, thereby preventing reaction with bulky polarization agents. We discover that the DNP SENS efficiency is correlated with the hydrophilicity of the SOMF/support, which depends on the carbon and SOMF concentration. Nitrogen sorption measurements to determine the BET constant (C-BET) were performed. This constant allows us to predict the aggregation of silica nanoparticles and consequently the efficiency of DNP SENS. Under optimal conditions, C-BET > 60, we found signal enhancement factors of up to 30. |
| Databáze: | OpenAIRE |
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