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Статті в журналах з теми "Identification par RMN 13C"
Bonnet, A., G. Barre, and P. Gilard. "« Trinoyaux ». Détermination des structures par RMN 1H, 13C et 15N." Journal de Chimie Physique 92 (1995): 1823–28. http://dx.doi.org/10.1051/jcp/1995921823.
Повний текст джерелаLe Botlan, D. J. "Etude par spectroscopie rmn 13C de la solution aqueuse formaldehyde-methanol." Journal de Chimie Physique 84 (1987): 115–23. http://dx.doi.org/10.1051/jcp/1987840115.
Повний текст джерелаElguero, J., R. Faure, E. J. Vincent, and R. Lazaro. "Étude Par RMN du 13C Du Benzothiazole et de Ses Dérivés Nitrés." Bulletin des Sociétés Chimiques Belges 86, no. 1-2 (September 1, 2010): 95–96. http://dx.doi.org/10.1002/bscb.19770860115.
Повний текст джерелаBaiwir, Marcel, Gabriel Llabres, Marie-Caroline Pardon, and Jean-Louis Piette. "Etude par RMN de composés organiques contenant des chalcogènes—IX.* RMN du 13C dans des dérivés aromatiques du tellurényle." Spectrochimica Acta Part A: Molecular Spectroscopy 42, no. 1 (January 1986): 57–61. http://dx.doi.org/10.1016/0584-8539(86)80132-5.
Повний текст джерелаGrenier-Loustalot, Marie-Florence, Laurence Orozco, and Philippe Grenier. "Etude structurale du prépolymère tetraglycidyl diamino diphenyl methane par RMN 13C et hplc." European Polymer Journal 22, no. 11 (January 1986): 921–32. http://dx.doi.org/10.1016/0014-3057(86)90068-6.
Повний текст джерелаGastmans, J. P., V. E. De Paula, and M. Furlan. "Etude par microordinateur de l'influence des atomes voisins sur les signaux RMN de 13C." Computers & Chemistry 12, no. 4 (January 1988): 285–87. http://dx.doi.org/10.1016/0097-8485(88)80001-9.
Повний текст джерелаGrenier-Loustalot, Marie-Florence, Dominique Renotte-Greco, and Philippe Grenier. "Etude des proprietes de surface par chromatographie gazeuse inverse de silices greffees caracterisees par RMN 13C et DSC." European Polymer Journal 29, no. 9 (September 1993): 1185–96. http://dx.doi.org/10.1016/0014-3057(93)90147-8.
Повний текст джерелаDa Silva Pinto, P. S., R. P. Eustache, M. Audenaert, and J. M. Bernassau. "Calculs empiriques de déplacements chimiques RMN 13C de polymères par régression multilinéaire et modélisation moléculaire." Revue de l'Institut Français du Pétrole 51, no. 1 (January 1996): 125–29. http://dx.doi.org/10.2516/ogst:1996011.
Повний текст джерелаBenayada, B., D. Nicole, JJ Delpuech, and G. Serratrice. "Détermination par RMN 13C des constantes de diffusion rotationnelles de molécules polyaromatiques à l'état de monomère." Journal de Chimie Physique 93 (1996): 427–41. http://dx.doi.org/10.1051/jcp/1996930427.
Повний текст джерелаMasse, M. O., C. Delporte, and E. Bervelt. "Identification de filtres solaires dérivés de l'acide para-aminobenzoique par spectroscopie RMN et par CPG/SM." International Journal of Cosmetic Science 23, no. 5 (October 2001): 259–79. http://dx.doi.org/10.1046/j.1467-2494.2001.00076.x.
Повний текст джерелаДисертації з теми "Identification par RMN 13C"
Palu, Doreen. "Etude de la composition chimique d’extraits d’Ilex aquifolium Linné et de Calicotome villosa (Poiret) Link de Corse par RMN du carbone-13." Electronic Thesis or Diss., Corte, 2022. http://www.theses.fr/2022CORT0018.
Повний текст джерелаThe aim of this work was to determine chemical composition of wild growing corsican understudied plant species, with potential biological activities. This study was realized using the computerized NMR method developed over the past thirty years by the University of Corsica “Chimie et Biomasse” group, UMR CNRS “Sciences Pour l’environnement”. Identified secondary metabolites were then undertaken to evaluate their antimicrobial properties. As part of this study, we selected on the first place commun holly (Ilex aquifolium L.). After two successive column chromatography, hexane and dichloromethane leaves crude extracts and all chromatography fractions were analyzed by 13C NMR (GC(RI) and GC-MS sometimes) to allow the identification of eleven triterpens and α- and β-amyrin esters. Among identified compounds, ursolic acid and oleanolic acid were also quantified by 1H NMR in the dichloromethane crude extract using a reliable method developped and validated (accuracy, linearity precision of measurements). Ursolic acid accounted for 55.3% of the extract, followed by oleanolic acid, 20.8%. Evaluation of previous identified compounds antimicrobial activities has been performed in collaboration with « Biochimie et Biologie Moléculaire du Végétal » group (University of Corsica). Triterpen acids and chloramphenicol (reference antibiotic) displayed similar antibacterial activities against three Gram-positive bacteria, Staphylococcus aureus, Staphylococcus epidermidis and Bacillus cereus (MIC = 4 and 8 mg.L-1 vs. 2 and 4 mg.L-1). Moreover, dichloromethane and dichloromethane/ethyl acetate (50/50, v/v) berries extracts were submitted to successive column chromatography. Crude extracts and chromatography fractions 13C NMR spectra revealed presence of nine triterpens previously identidied, five phenolics derivatives, six monosaccharides and four lactones (menisdaurilide, aquilegiolide, dasycarponilide and 7-epi-griffonilide) were first time identified in berries holly extracts. On the second place, we determined chemical compositions of Calicotome villosa (Poir.) Link flowers and root extracts. 13C NMR analysis of dichloromethane and ethyl acetate flowers extracts and their chromatography fractions, allowed the identification of three flavonoids, five glycosyl flavonoids and four phenylpropanoids. We also studied chemical composition of a methanol root extract which has never been submitted to any chemical composition study. After successive column chromatography, eighteen compounds were identified by 13C NMR including sterols, flavonoids, a polyphenol and pterocarpans
Zink, Olivier. "Identification de l'HPP oxydase d'Arthrobacter globiformis et de la 4-HPA 1-hydroxylase de Pseudomonas acidovorans : étude du métabolisme de la tyrosine par des cellules végétales en utilisant la 13C-RMN." Grenoble 1, 2000. http://www.theses.fr/2000GRE10192.
Повний текст джерелаGasmi, Geneviève. "Developpement de nouvelles sequences d'impulsions en rmn : etude du nosiheptide (antibiotique cyclopeptidique) par rmn 1h, 13c, 15n." Reims, 1993. http://www.theses.fr/1993REIMP204.
Повний текст джерелаCaytan, Elsa. "Détermination de la distribution intramoléculaire du 13C en abondance naturelle par RMN quantitative." Nantes, 2006. http://www.theses.fr/2006NANT2034.
Повний текст джерелаExperimental conditions for the determination of the intramolecular distribution of 13C by NMR have been studied. In the first instance, 13C bi-labelled molecules were used to evaluate the performance of analytical methods (accuracy, precision). Two strategies were then set up for reducing the duration of the analysis. The use of relaxation agents enables a reduction of the repetition delay, and polarisation transfer sequences, such as INEPT, enhance sensibility. The effects of RF pulses imperfections on the INEPT sequence have been modelled, and the INEPT sequence optimised by use of adiabatic pulses and modifications to phase cycling. The methods developed make possible the precise quantitative analysis by 13C NMR of 13C/12C isotopic ratios, which can be applied in studies of isotopic fractionation and in the authentication of natural products
Bailac, Laura. "Composés organiques fluorés : Étude par RMN multinoyaux {1H, 13C, 19F} et calculs DFT." Rouen, 2016. http://www.theses.fr/2016ROUES008.
Повний текст джерелаFor more than 40 years, fluorinated compounds have become increasingly important in the field of pharmaceutical, food chemistry and polymers. The knowledge of the 3D structure of those compounds can be of great importance especially in the case of molecule interaction studies. NMR is the most powerful method for the structural characterization of synthetic and natural compounds. Moreover, fluorine 19 owns remarkable magnetic properties which make it an interesting probe for the structural characterization of fluorinated organic compounds by NMR. During this project, a thorough structural study of fluorinated compounds by NMR and DFT has been realized. Recent NMR experiments, using selective pulses and encoding gradient such as the 1D Pure Shift and 2D G-SERF experiments, helped extract very accurate spectroscopic data such as chemical shifts and homo- and heteronuclear scalar coupling constants. Those spectroscopic data have been then completed by structural data such as internuclear distances and dihedral angles obtained by DFT geometry optimization of those compounds. In the second part of this work, the data obtained by NMR were used to develop a DFT computational model using a benchmark to predict, from the 3D structure, the heteronuclear coupling constants nJHF. This model also allows to determine the different contributions composing the scalar coupling. The access to each contribution's weight for a given coupling allows a better understanding of the mechanism of coupling's transmission, in particular in the case of long distance scalar couplings
Gilbert, Alexis. "Méthodologies pour l'étude du fractionnement isotopique photosynthétique et post-photosynthétique par RMN 13C isotopique." Nantes, 2010. http://www.theses.fr/2010NANT2049.
Повний текст джерелаA methodology has been developed that makes possible the determination of the site specific carbon-13 isotopic composition of glucose, fructose and sucrose using isotopic 13C NMR. The derivatization of sugars as their acetonides is a prerequisite to accessing the desired information. Once the protocol for the derivatization was perfected, the methodology can attain a precision of 1‰ or better. Analyses of ethanols derived from sugars by fermentation show a good correlation with results obtained by the methodology developped. The ethanol molecule has also been used as a probe to show the influence of climatic parameters (temperature, sunshine, rainfall) on the intra-molecular 13C isotope distribution in sugars from grapes. Moreover, results for sugars or starch from plants having C3 or C4 metabolism show there to be an intramolecular 13C distribution characteristic of the type of carbon assimilatory pathway exploited. The hypothesis proposed here indicates that the CO2 assimilation mode is not the only factor affecting the intra-molecular 13C distribution in sugars. It appears that isomerisation steps (involving trioses phosphates or hexoses phosphates) are crucial in terms of isotopic fractionation in the sugars produced during photosynthesis. We have therefore measured the isotope effects associated with the transformation of glucose to fructose, catalysed by glucose isomerase. A clear equilibrium isotope effect is observed, which is shown to be responsible for the C-1 enrichment and the C-2 depletion of glucose, and a significant kinetic isotope effect on the C-2 of glucose is also seen during the conversion of fructose to glucose
Schahl, Adrien. "Interactions polysaccharides-lipides : étude théorique et expérimentale combinant calculs de dynamique moléculaire, calculs quantiques de spectres RMN 13C et RMN 13C à l'état solide." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30178.
Повний текст джерелаPolysaccharide-lipid interactions now form a vast domain of study, of particular interest to the pharmaceutical and food industries. We already know that amylose, an essentially linear polysaccharide composed of [alpha 1→4]-linked glucose moieties, can form helices around small hydrophobic molecules and lipidic chains. These helical structures are called V polymorphs and their study may allow the development of new ways to deliver bioactive compounds, or of new vaccine adjuvants. This type of interaction might also be found in other biological systems, such as in the capsule of Mycobacterium tuberculosis. Indeed, this external layer covering the bacillus is composed mostly of a large branched polysaccharide analogous to amylose, called alpha-glucan, but it also contains numerous lipids, such as phtiocerol dimycocerosates or trehalose dimycolates, known to be virulence factors of the mycobacterium. Demonstration of the existence of such interactions and their study may lead to a better understanding of the capsule and its biological functions. This manuscript describes a study combining theoretical and experimental methods to characterize the interactions amongst amylose complexes formed in the presence of classical and mycobacterial lipids and in systems composed of branched polysaccharides. The first part of this work describes two purely theoretical studies on amylose complexed with palmitic acid and on amylose double helices called B polymorphs. Using molecular dynamics (MD) simulations and calculations of Nuclear Magnetic Resonance (NMR) parameters at the Density Functional Theory (DFT) level, we were able to define the minimum number of glucose residues needed to former a stable V polymorph around a palmitic acid molecule. We could also show that the number of residues has a direct impact on the calculation of NMR parameters and that it is crucial to consider the dynamic behavior of these polymers to obtain results that fit well to experimental data. Regarding the B polymorph, we showed that it is essential/necessary to consider the periodic conditions of the system to be able to characterize two different residue positions, as has been observed experimentally. To the best of our knowledge, no V polymorph has been characterized in the presence of lipids composed of several lipidic chains. The second part of this manuscript describes several such complexes, formed in the presence of classical and mycobacterial lipids composed of 1, 2 or 4 lipidic chains, and their analysis by solid-state NMR. We elaborated a model describing the different equilibria implicated in the complexation process and could demonstrate that the primary structure of the lipids was one of the key factors. [...]
Bruguière, Antoine. "Mise au point d’une méthode d’analyse déréplicative par RMN du carbone 13." Thesis, Angers, 2019. http://www.theses.fr/2019ANGE0085.
Повний текст джерелаExtraction and isolation of natural products can be a tedious and time-consuming work and can unfortunately lead to molecules presenting little to no interest. That is why dereplication methods have been developed : they allow the identification of molecules within a mixture, without having to separate them, by comparing their signals to those of references, gathered in databases. In this work, we try to focus on polycyclic polyprenylated acylphloroglucinols (PPAPs), molecules that could be used a therapeutic tool to understand mechanisms involved in immune and inflammatory responses. We first were able to conclude that building databases using predicted values, instead of experimental ones, gave quality results for a dereplication work. Predicted databases were thus used for the rest of the experiments. After taking a look at the different kind of published dereplication methods, we decided to develop our own program based on 13C-NMR, in order to make it more discriminating than the current methods. To do so, in addition to 13C data, DEPT (135 and 90) information were added, allowing to narrow the search by carbon type. A graphic user interface was also implemented, making the program easier to use, but also providing the user with the possibility to interact with the results. This new method was first successfully tested on a diverse range of natural products mixtures, allowing the validation of the method. In the end, the method was used on Garcinia bancana extracts, and made possible the quick identification of the PPAPs we were interested in. Molecules were purified for further biological testing
Lecachey, Baptiste. "Etudes structurales d’agrégats mixtes organolithiés par RMN multinoyaux 1H, 6Li, 13C. : Applications en additions nucléophiles énantiosélectives." Rouen, 2009. http://www.theses.fr/2009ROUES012.
Повний текст джерелаThree NMR studies of characterization of mixed aggregates in solution were conducted during this work. Complex MeLi / LiCl: The so-called “low halide” solutions of methyllithium, contain 2 to 5% molar of lithium chloride. This salt exerts a strong influence on many enantioselective processes; it was thus essential to determine how it interacts with MeLi in THF at low temperature. The single formation of trimer [(MeLi)(LiCl)2], in equilibrium with MeLi and LiCl tetramers in THF, is evidenced. This aggregation contrasts with the cubic tetramers known for MeLi / LiBr and MeLi / LiI. Complex LiCl / o-TolCH(Me)OLi: In the enantioselective condensation of MeLi on the o-tolualdehyde in the presence of a chiral lithium amide derived from a 3-aminopyrrolidine (3AP-Li), the lithium alkoxide (Al-Li) formed impounds the ligand, and thus limits the induction. The addition of lithium chloride together with the aldehyde on the complex 3AP-Li / MeLi allowed to trap the alkoxide forming a cubic aggregate incorporating one LiCl and three Al-Li. This procedure give access to a version of the 1,2 addition in which substoichiometric amount of chiral ligand (33% mol) can be used. Complexes 3AP-Li / lithium enolate: The 1,4 enantioselective nucleophilic addition of lithium enolates (En-Li) on tert-butyl crotonate in the presence of 3AP-Li led to e. E. ’s up to 76%. The complexes formed between 3AP-Li and En-Li are described here. With a 1 to 1 stoichiometry in THF, they are comparable to those formed between 3AP-Li and alkyllithium
El, Hage Maha. "Caractérisation du métabolisme cérébral chez le rat : étude par spectroscopie RMN du carbone 13." Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10101.
Повний текст джерелаThis study was conducted to obtain a better knowledge of brain metabolism which is altered in many neurological diseases or by drugs with toxic effects on the central nervous system. For this purpose, we used our cellular metabolomic approach that combines enzymatic and carbon 13 NMR measurements with mathematical modeling of metabolic pathways. In the first part of this work, we characterized the metabolism of rat brain slices by using the main substrates of the brain. Our slices metabolized and oxidized these substrates at high rates during the incubation period. The second part presents a validation of our model of study by testing the effect of valproate, a widely used antiepileptic drug. We showed that valproate not only increases the accumulation of GABA and decreases that of aspartate, but also alters fluxes through several enzymes involved in brain metabolism. In the third part, we investigated the effects of guanidino compounds on cerebral metabolism; these compounds increase glucose consumption and lactate accumulation by rat brain slices. Thus, our slices are a good model for metabolic studies in vitro and our approach provides an overview of the metabolic fate of a given substrate and allows to identify the metabolic pathways involved by measuring enzymatic fluxes in the absence and the presence of a pharmacological or toxicological agents