Papers by Dorothee Berthomieu
Studies in Surface Science and Catalysis, 2002
Calcium oxalate minerals of general formula CaC2O4. xH2O are widely present in nature and usually... more Calcium oxalate minerals of general formula CaC2O4. xH2O are widely present in nature and usually associated with pathological calcifications, constituting up to 70-80% of the mineral component of renal calculi. The monohydrate phase (CaC2O4. H2O, COM) is the most stable form, accounting for the majority of the hydrated calcium oxalates found. These mineral phases have been studied extensively via X-ray diffraction, IR spectroscopy and, to a lesser extent, using 1 H, 13 C and 43 Ca solid-state NMR spectroscopy. However, several aspects of their structure and reactivity are still unclear, such as the evolution from low-to high-temperature COM structures (LT-COM and HT-COM, respectively), and the involvement of water molecules in this phase transition. Here, we report for the first time a 17 O and 2 H solid-state NMR investigation of the local structure and dynamics of water in the COM phase. A new procedure for the selective 17 O-and 2 H-isotopic enrichment of water molecules within the COM mineral is presented using mechanochemistry, which employs only microliter quantities of enriched water, and leads to exchange yields up to ~30%. 17 O NMR allows both crystallographically inequivalent water molecules in the LT-COM structure to be resolved, while 2 H NMR studies provide unambiguous evidence that these water molecules are undergoing different types of motions at high temperatures without exchanging with one another. Dynamics appear to be essential for water molecules in these structures, which have not been accounted for in previous structural studies on the HT-COM structure due to lack of available tools-highlighting the importance of such NMR investigations for refining the crystallographic data of biologically relevant minerals like calcium oxalates.
HAL (Le Centre pour la Communication Scientifique Directe), 2014
National audienc
Journal of Physical Chemistry C, Jul 19, 2022
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires
Physical Chemistry Chemical Physics, 2022
We calculated the Raman spectra of thiophenol molecules adsorbed on a real flat gold surface. Our... more We calculated the Raman spectra of thiophenol molecules adsorbed on a real flat gold surface. Our results demonstrate that the orientation of the molecule on the metallic surface plays a key role in the interpretation of the SER spectra.
Wiley-VCH Verlag GmbH & Co. KGaA eBooks, Jun 8, 2004
Catalysis Reviews-science and Engineering, Sep 1, 2006
An overview of the CuY material is performed on the basis of the results obtained during the last... more An overview of the CuY material is performed on the basis of the results obtained during the last 5 years on their structure (nature of the Cu species, siting, coordination …), their use and reactivity, based on TPR, XRD and various ex situ and in situ spectroscopies such as XAS, IR and EPR. A brief summary of previous work is
HAL (Le Centre pour la Communication Scientifique Directe), May 1, 2009
NH&u{ 1101 high coverage N.O.' 560 1130 1600 34004 ND&u{ 110) high coverage N.O.* N.0.t 870 1190 ... more NH&u{ 1101 high coverage N.O.' 560 1130 1600 34004 ND&u{ 110) high coverage N.O.* N.0.t 870 1190 2420 2520 l Not observed. t Possibly not observed due IO a low impact scattering cross-section. 4 We believe that this loss is dominated by v,(NH) with the result that two distinct bands are no longer observed.
Calcium oxalate minerals of general formula CaC2O4. xH2O are widely present in nature and usually... more Calcium oxalate minerals of general formula CaC2O4. xH2O are widely present in nature and usually associated with pathological calcifications, constituting up to 70-80% of the mineral component of renal calculi. The monohydrate phase (CaC2O4. H2O, COM) is the most stable form, accounting for the majority of the hydrated calcium oxalates found. These mineral phases have been studied extensively via X-ray diffraction, IR spectroscopy and, to a lesser extent, using 1 H, 13 C and 43 Ca solid-state NMR spectroscopy. However, several aspects of their structure and reactivity are still unclear, such as the evolution from low-to high-temperature COM structures (LT-COM and HT-COM, respectively), and the involvement of water molecules in this phase transition. Here, we report for the first time a 17 O and 2 H solid-state NMR investigation of the local structure and dynamics of water in the COM phase. A new procedure for the selective 17 O-and 2 H-isotopic enrichment of water molecules within the COM mineral is presented using mechanochemistry, which employs only microliter quantities of enriched water, and leads to exchange yields up to ~30%. 17 O NMR allows both crystallographically inequivalent water molecules in the LT-COM structure to be resolved, while 2 H NMR studies provide unambiguous evidence that these water molecules are undergoing different types of motions at high temperatures without exchanging with one another. Dynamics appear to be essential for water molecules in these structures, which have not been accounted for in previous structural studies on the HT-COM structure due to lack of available tools-highlighting the importance of such NMR investigations for refining the crystallographic data of biologically relevant minerals like calcium oxalates.
Journal of Catalysis, Jul 1, 2004
Industrial & Engineering Chemistry Research, Oct 23, 2018
Cu-SSZ-13 efficiently catalyzes the selective catalytic reduction (SCR) of NO by NH 3 but the str... more Cu-SSZ-13 efficiently catalyzes the selective catalytic reduction (SCR) of NO by NH 3 but the structure of the active site and, particularly, the redox state of the copper (+I or +II) are still debated. This paper focuses on the possible contribution of Cu I species with a theoretical investigation of adsorption and co-adsorption of NH 3 and H 2 O on Cu I species using quantum chemistry and including dispersion forces. The calculations show that Cu I clearly migrates upon adsorption of NH 3. While Cu I is initially in close interaction with the zeolite framework, it preferentially forms coordination bonds with NH 3 and interacts with the zeolite in its second coordination sphere. The same tendency is calculated with H 2 O, even if the binding energy of H 2 O with Cu I is lower than with NH 3. All the Cu I complexes sit in the cage containing the 8 MR. The confined Cu I complexes interact with the zeolite framework through several H-bonds donated by the NH or OH bonds of the ligands. In the experimental temperature and pressure domain of SCR conditions, calculated phase diagrams show that coordination number of two is predicted for the co-adsorption of NH 3 and H 2 O on Cu I. For pure H 2 O, few stable domains for hydrated species containing Cu I are calculated in contrast with pure NH 3. Finally, the calculated phase diagrams on Cu I-SSZ-13 are discussed together with the more documented diagrams of Cu II-SSZ-13 and recent experimental characterizations, providing a wider picture of the real catalyst in SCR conditions. ORCID D.
HAL (Le Centre pour la Communication Scientifique Directe), 2001
Publisher Summary This chapter discusses modeling transition-metal cations in zeolites. Density f... more Publisher Summary This chapter discusses modeling transition-metal cations in zeolites. Density functional theory has been used to study model clusters of zeolites Y and β containing Fe(II), Co(II), and Cu(II) TM cations. The calculations yield a charge of around +1 on TM, whatever are their coordination, size of the cluster, and aluminum (Al) distribution. The TM-zeolite system behaves as a supermolecule and that the zeolite is able to keep or release electrons when reactive molecules are incoming.
Rapid Communications in Mass Spectrometry, 1995
In the gas phase, π‐complexes are common intermediates in unimolecular reactions of metastable pr... more In the gas phase, π‐complexes are common intermediates in unimolecular reactions of metastable protonated alkylbenzenes. The transient formation of two π‐complexes generated from protonated dialikylbenzenes has been proposed in the Literature, even when the substitution degree of the two benzylic carbons is different. For metastable tert‐C4H9C6H5R+ cations (R ‐ n‐C4H9, sec‐C4H9, iso‐C4H9), we demonstrate in this paper that the [tert‐C4H, C6H5‐R] π‐complex is produced and does not interconvert into the [tert‐C4H9C6H5, R+] π‐complex prior to fragmentation.
ChemInform, Feb 28, 2006
reference to the experimental data, under the so-called maximum entropy principle. Recent practic... more reference to the experimental data, under the so-called maximum entropy principle. Recent practical formulations of this approach involve simulations carried out over multiple replicas or iterative ensemble-correction procedures based on the determination of several (Lagrange) parameters. Here, we present an alternative, self-learning approach to sample molecular ensembles compatible with experimental data with the minimal possible bias on the simulation trajectories. The method does not require multiple replicas and is based on adding an adaptive bias potential during the simulation that discourages the sampling of conformations that are not consistent with the experimental measurements. To illustrate this approach, we applied this novel simulation technique to spin-labeled T4-lysozyme, targeting a set of spin-spin distance distributions measured by DEER/EPR spectroscopy. We show how the proposed method is able to efficiently sample the experimental distance distributions without altering uncorrelated degrees of freedom. We anticipate that this new simulation approach will be widely useful to obtain conformational ensembles compatible with diverse types of experimental measurements of biomolecular dynamics.
Chemistry: A European Journal, Jan 7, 2013
Journal de chimie physique, 1992
The reaction of metastable decomposing ions 1 to 5 are reported and discussed. The unimolecular d... more The reaction of metastable decomposing ions 1 to 5 are reported and discussed. The unimolecular decomposition pathways of these ions are explained in terms of mechanisms involving proton-bound complexes as intermediates. The results derived from labelled precursors together with thermochemical data indicate that the decompositions of these complexes are governed by the proton affinity of the neutral counterparts
Journal of Physical Chemistry C, Dec 16, 2020
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Papers by Dorothee Berthomieu