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1.
Romain Plais Guy Gouarin Dr. Anne Gaucher Violette Haldys Arnaud Brosseau Dr. Gilles Clavier Dr. Jean-Yves Salpin Prof. Dr. Damien Prim 《Chemphyschem》2020,21(12):1249-1257
The intrinsic properties of tetrazine as a π-anion receptor and as an on/off recognition probe merged with H-bond ability of an urea motif into a single architecture constitutes a new generation of well-defined anion receptors. Complexation properties directly benefit from the dual and synergistic contribution of tetrazine and urea. In this study, we report on the synthesis and assessment of binding properties to anions of diverse geometries. Association constants have been predicted by theoretical calculations and evaluated by multiple and complementary experimental techniques including electrospray-mass tandem spectroscopy, NMR, UV-visible, steady state fluorescence spectroscopies and time resolved fluorescence. These results provide the basis for a better understanding of both the complexation and the anion-dependent quenching mechanism. 相似文献
2.
Amine Kassouf Maria El Rakwe Hanna Chebib Violette Ducruet Douglas N. Rutledge Jacqueline Maalouly 《Analytica chimica acta》2014
Olive oil is one of the most valued sources of fats in the Mediterranean diet. Its storage was generally done using glass or metallic packaging materials. Nowadays, plastic packaging has gained worldwide spread for the storage of olive oil. However, plastics are not inert and interaction phenomena may occur between packaging materials and olive oil. In this study, extra virgin olive oil samples were submitted to accelerated interaction conditions, in contact with polypropylene (PP) and polylactide (PLA) plastic packaging materials. 3D-front-face fluorescence spectroscopy, being a simple, fast and non destructive analytical technique, was used to study this interaction. Independent components analysis (ICA) was used to analyze raw 3D-front-face fluorescence spectra of olive oil. ICA was able to highlight a probable effect of a migration of substances with antioxidant activity. The signals extracted by ICA corresponded to natural olive oil fluorophores (tocopherols and polyphenols) as well as newly formed ones which were tentatively identified as fluorescent oxidation products. Based on the extracted fluorescent signals, olive oil in contact with plastics had slower aging rates in comparison with reference oils. Peroxide and free acidity values validated the results obtained by ICA, related to olive oil oxidation rates. Sorbed olive oil in plastic was also quantified given that this sorption could induce a swelling of the polymer thus promoting migration. 相似文献
3.
Latifa Latrous Jeanine Tortajada Violette Haldys Emmanuelle Léon Catarina Correia Jean‐Yves Salpin 《Journal of mass spectrometry : JMS》2013,48(7):795-806
Gas‐phase interactions of organotins with glycine have been studied by combining mass spectrometry experiments and quantum calculations. Positive‐ion electrospray spectra show that the interaction of di‐ and tri‐organotins with glycine results in the formation of [(R)2Sn(Gly)‐H]+and [(R)3Sn(Gly)]+ ions, respectively. Di‐organotin complexes appear much more reactive than those involving tri‐organotins. (MS/MS) spectra of the [(R)3Sn(Gly)]+ ions are indeed simple and only show elimination of intact glycine, generating the [(R)3Sn]+ carbocation. On the other hand, MS/MS spectra of [(R)2Sn(Gly)‐H]+complexes are characterized by numerous fragmentation processes. Six of them, associated with elimination of H2O, CO, H2O + CO and formation of [(R)2SnOH]+ (?57 u),[(R)2SnNH2]+( ?58 u) and [(R)2SnH]+ (?73 u), are systematically observed. Use of labeled glycines notably concludes that the hydrogen atoms eliminated in water and H2O + CO are labile hydrogens. A similar conclusion can be made for hydrogens of [(R2)SnOH]+and [(R2)SnNH2]+ions. Interestingly, formation [(R)2SnH]+ ions is characterized by a migration of one the α hydrogen of glycine onto the metallic center. Finally, several dissociation routes are observed and are characteristic of a given organic substituent. Calculations indicated that the interaction between organotins and glycine is mostly electrostatic. For [(R)2Sn(Gly)‐H]+complexes, a preferable bidentate interaction of the type η2‐O,NH2 is observed, similar to that encountered for other metal ions. [(R)3Sn]+ ions strongly stabilize the zwitterionic form of glycine, which is practically degenerate with respect to neutral glycine. In addition, the interconversion between both forms is almost barrierless. Suitable mechanisms are proposed in order to account for the most relevant fragmentation processes. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
4.
Alain Guinault Cyrille Sollogoub Violette Ducruet Sandra Domenek 《European Polymer Journal》2012,48(4):779-788
The helium and oxygen gas barrier properties of poly(lactide) were investigated as a function of stereochemistry and crystallinity degree. Poly(l-lactide) and poly(d,l-lactide) films were obtained by extrusion and thermally cold crystallized in either α′- or α-crystalline form with increasing crystallinity degree. Annealing of the films at low temperatures yielded to α′-crystals as well as the creation of a rigid amorphous fraction in the amorphous phase. Unexpectedly, the quantity of the rigid amorphous fraction was highest in poly(l-lactide) crystallized under α′-form. Unexpectedly, the gas permeability increased with increasing quantity of α′-crystals in poly(l-lactide) and remained constant with increasing quantity of α′-crystals in poly(d,l-lactide). A gain in gas barrier properties was obtained upon crystallization at higher temperatures yielding α-crystals. The analysis of the oxygen transport parameters, in particular the diffusion and the solubility coefficient showed that the diffusion was accelerated upon crystallization, while the solubility coefficient decreased in an expected manner which led to conclude that it remained constant in the amorphous phase. The acceleration of the diffusion seems to be correlated to the occurrence of the rigid amorphous fraction, which holds larger free volume. To conclude, for optimization of poly(lactide) gas barrier properties by focussing on the decrease of the diffusion coefficient it can be suggested to work with poly(d,l-lactide) and to aim a crystallization in α-form avoiding the formation of a rigid amorphous fraction. 相似文献
5.
Back Cover: Simultaneous Assessment of Kinetic,Site‐Specific,and Structural Aspects of Enzymatic Protein Phosphorylation (Angew. Chem. Int. Ed. 36/2014) 下载免费PDF全文
6.
Harry A. Frank Mila L. Aldema Carol A. Violette Pierre H. Parot † 《Photochemistry and photobiology》1991,54(1):151-155
The absorbance and polarized absorbance spectra of single crystals of the reaction center complex isolated from Rhodobacter sphaeroides wild type strain 2.4.1 have been measured at 85 K. The crystals of the complex were obtained by the vapor diffusion technique. The spectroscopic experiments on the crystals were performed using an optical microspectrometer featuring a custom-built, liquid N2-flowing cold stage, the details of which are presented herein. These data demonstrate the feasibility of conducting optical spectroscopic experiments at cryogenic temperatures on single crystals of photosynthetic pigment-protein complexes. 相似文献
7.
Structures of [M(Ura‐H)(H2O)n]+ (M = Mg,Ca, Sr,Ba; n = 1–3) complexes in the gas phase by IRMPD spectroscopy and theoretical studies 下载免费PDF全文
Barry Power Violette Haldys Jean‐Yves Salpin Travis D. Fridgen 《Journal of mass spectrometry : JMS》2016,51(3):236-244
The structures of singly and doubly (and for Mg, triply) hydrated group 2 metal dications bound to deprotonated uracil were explored in the gas phase using infrared multiple photon dissociation spectroscopy in the mid‐infrared region (1000–1900 cm?1) and the O–H/N–H stretching region (2700–3800 cm?1) in a Fourier transform ion cyclotron resonance mass spectrometer. The infrared multiple photon dissociation spectra were then compared with the computed IR spectra for various isomers. Calculations were performed using B3LYP with the 6‐31 + G(d,p) basis set for all atoms except Ba2+ and Sr2+, for which the LANL2DZ or the def2‐TZVPP basis sets with relativistic core potentials were used. Atoms‐in‐molecules analysis was conducted for all lowest energy structures. The lowest energy isomers in all cases are those in which the one uracil is deprotonated at the N3 position, and the metal is coordinated to the N3 and O4 of uracil. Regardless of the degree of solvation, all water molecules are bound to the metal ion and participate in a hydrogen bond with a carbonyl of the uracil moiety. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
8.
Summary Conductance measurements of acidified sodium aluminate solutions showed a gradual drop as the alumina content of the solution increases. This behaviour was explained by adsorption of H+ ions, as visualised from linear plots of (
0–) per mole of alumina against
(where
0 is the specific conductance of the corresponding (NaOH + HCl), is the specific conductance of (sodium aluminate + HCl) and
is the amount of H+ ions adsorbed per mole of alumina). Transport number experiments showed that alumina behaves as a non-electrolyte and that the transport number of the Cl– ion increases with increase in alumina content. This behaviour was explained on the basis of aggregation of water molecules around alumina.The zero point of charge of colloidally dispersed aluminium hydroxide was determined from potentiometric and conductance measurements.
Zusammenfassung Leitfähigkeitsmessung von angesäuerten Natrium-Aluminat-Lösungen zeigen einen Abfall, wenn der Aluminat-Gehalt der Lösungen wächst. Dieses Verhalten wird durch Adsorption von Wasserstoff-Ionen erklärt, erkennbar aus der linearen Auftragung von ( 0–) pro Mol/Aluminat gegen Dabei ist 0 die spezifische Leitfähigkeit der entsprechenden (NaOH + HCl)-Lösung, die spezifische Leitfähigkeit vom Gemisch Natriumaluminat + HCl und der Betrag an Wasserstoffionen, adsorbiert pro Mol/Aluminat. überführungszahl-Experimente zeigen, daß Alumina sich nicht als Elektrolyt verhält und daß die überführungszahl für Cl–-Ionen mit dem Alumina-Anteil wächst. Dieses Verhalten wird erklärt auf Grund einer Aggregation von Wassermolekülen um das Alumina.Der Neutralpunkt für Ladung von kolloidal dispergiertem Alumiumhydroxid wurde aus potentiometrischen und Leitfähigkeitsmessungen bestimmt.相似文献
9.
Ducruet JM Serrano A Roncel M Ortega JM 《Journal of photochemistry and photobiology. B, Biology》2011,104(1-2):301-307
The microalgae Chlamydomonas reinhardtii and Chlorella sp. CCAP 211/84 were grown autotrophically and mixotrophically and their thermoluminescence emissions were recorded above 0 °C after excitation by 1, 2 or 3 xenon flashes or by continuous far-red light. An oscillation of the B band intensity according to the number of flashes was always observed, with a maximum after 2 flashes, accompanied by a downshift of the B band temperature maximum in mixotrophic compared to autotrophic grown cells, indicative of a dark stable pH gradient. Moreover, new flash-induced bands emerged in mixotrophic Chlamydomonas grown cells, at temperatures higher than that of the B band. In contrast to the afterglow band observed in higher plants, in Chlamydomonas these bands were not inducible by far-red light, were fully suppressed by 2 μM antimycin A, and peaked at different temperatures depending on the flash number and growth stage, with higher temperature maxima in cells at a stationary compared to an exponential growth stage. These differences are discussed according to the particular properties of cyclic electron transfer pathways in C. reinhardtii. 相似文献
10.
Metcalf CA Eyermann CJ Bohacek RS Haraldson CA Varkhedkar VM Lynch BA Bartlett C Violette SM Sawyer TK 《Journal of combinatorial chemistry》2000,2(4):305-313
Using a novel, solid-phase parallel synthetic route and a computational docking program, a series of phosphorylated nonpeptides were generated to determine their structure-activity relationships (SAR) for binding at the SH2 domain of pp60src (Src). A functionalized benzoic acid intermediate was attached to solid support via Rink amide linkage, which upon acid cleavage generated the desired benzamide template-based nonpeptides in a facile manner. Compounds were synthesized using a combination of solid- and solution-phase techniques. Purification using reversed-phase, semipreparative HPLC allowed for quantitative SAR studies. Specifically, this work focused on functional group modifications, in a parallel fashion, designed to explore hydrophobic binding at the pY+3 pocket of the Src SH2 domain. 相似文献