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81.
Antoine Leydier Yi Lin Guilhem Arrachart Raphaël Turgis Delphine Lecerclé Alain Favre-Reguillon Frédéric Taran Marc Lemaire Stéphane Pellet-Rostaing 《Tetrahedron》2012,68(4):1163-1170
Synthesis of modified EDTA and DTPA ligands and determination of their binding affinities for the uranyl cation are described.Thanks to a screening method, based on a chromophoric complex displacement procedure, chelating properties were studied in aqueous media under various pH conditions for evaluation of their in vivo uranyl-removal efficacy. Each ligand showed a more or less pronounced affinity for uranium. Specific ligands based on EDTA or DTPA analogues containing sulfocatecholamide (CAMS) were found to exhibit a significant affinity towards uranyl ion in acidic, neutral or basic conditions. 相似文献
82.
Delphine Declerck Albert Nguyen Van Nhien Solen Josse Jan Szymoniak Philippe Bertus Claudia Bello Pierre Vogel Denis Postel 《Tetrahedron》2012,68(6):1802-1809
The titanium-mediated cyclopropanation reaction using Ti(OiPr)3Me/EtMgBr/BF3·OEt2 has been applied to various 2-cyanopyrrolidines for the synthesis of functionalized 2-(1-aminocyclopropyl)pyrrolidine-3,4-diol derivatives (dideoxyiminoalditols). Under the same experimental conditions the trans-5-azidomethyl-2-cyanopyrrolidine derivative was not cyclopropanated but reduced into the corresponding 5-amino-2-cyano derivative. After polyol deprotection 2-(1-aminocyclopropyl)pyrrolidine-3,4-diols were obtained and their inhibitory activity towards 13 glycosidases has been evaluated. (2S,3S,4R,5S)-2-(1-Aminocyclopropyl)-5-methylpyrrolidine-3,4-diol (38), which has the same absolute configuration as l-fucose, is a moderate (IC50=44 μM), but selective, inhibitor of α-l-fucosidase from human placenta. 相似文献
83.
L Ruhlmann D Schaming I Ahmed A Courville J Canny R Thouvenot 《Inorganic chemistry》2012,51(15):8202-8211
The reaction of the trivacant Dawson polyoxometalate α-[P(2)W(15)O(56)](12-) and the divalent cations Co(2+) is known to form a symmetrically derived sandwich complex of formula ββ-[Co(4)(H(2)O)(2)(P(2)W(15)O(56))(2)](16-) [symbolized as ββ-Co(4)(P(2)W(15))(2)] at low pH (ca. pH 3). We have shown previously that, by a slight modification of the reaction conditions, trinuclear αβ-[(NaOH(2))Co(3)(H(2)O)(P(2)W(15)O(56))(2)](17-) and dinuclear [(NaOH(2))(2)Co(2)(P(2)W(15)O(56))(2)](18-) complexes [symbolized as αβ-NaCo(3)(P(2)W(15))(2) and Na(2)Co(2)(P(2)W(15))(2), respectively] can be synthesized as aqueous-soluble sodium salts. αβ-NaCo(3)(P(2)W(15))(2) is a "lacunary" sandwich complex that can add a Co(2+) cation to form nearly quantitatively an unsymmetrical Dawson tetracobalt sandwich polyoxometalate, αβ-[Co(4)(H(2)O)(2)(P(2)W(15)O(56))(2)](16-) [symbolized as αβ-Co(4)(P(2)W(15))(2)]. Thus, for Co(4)(P(2)W(15))(2), the junctions between the trivacant {P(2)W(15)} subunits and the central tetrameric unit can be either both β type or β and α types. The interconversion between αβ-Co(4)(P(2)W(15))(2) and ββ-Co(4)(P(2)W(15))(2) and the decomplexation process at low pH, leading to the formation of αβ-NaCo(3)(P(2)W(15))(2) and/or Na(2)Co(2)(P(2)W(15))(2), have been followed in aqueous solution at various pH values by electrochemistry, UV-visible absorption spectroscopy, and (31)P NMR spectroscopy. 相似文献
84.
Delphine Salort 《Journal of Differential Equations》2007,233(2):543-584
We consider the Liouville equation associated with a metric g of class C2 and we prove dispersion and Strichartz estimates for the solution of this equation in terms of geodesics associated with g. We introduce the notion of focusing and dispersive metric to characterize metrics such that the same dispersion estimate as in the Euclidean case holds. To deal with the case of non-trapped long range perturbation of the Euclidean metric, we prove a global velocity moments effect on the solution. In particular, we obtain global in time Strichartz estimates for metrics such that the dispersion estimate is not satisfied. 相似文献
85.
Francois Ribot Delphine Veautier Steve Guillaudeu Thierry Lalot 《Journal of Sol-Gel Science and Technology》2004,32(1-3):37-41
Hybrid copolymers have been prepared by free radical polymerization, in toluene, of methylacrylate (MA) and varying amounts of an organotin oxo-cluster functionalized with two acrylamido groups, {(BuSn)12O14(OH)6}(AMPS)2. The tin based nanobuilding block is fully preserved in the final materials. These copolymers formed networks where the cross-linking is based on the electrostatic interactions that take place between the macrocation {(BuSn)12O14(OH)6}2 + and its two functional anions (AMPS–). Accordingly, these copolymers can yield gels or solutions depending on the solvent used to swell them. 相似文献
86.
The amino acid selenocysteine represents the major biological form of selenium. Both the synthesis of selenocysteine and its co-translational incorporation into selenoproteins in response to an in-frame UGA codon, require a complex molecular machinery. To decode the UGA Sec codon in eubacteria, this machinery comprises the tRNASec, the specialized elongation factor SelB and the SECIS hairpin in the selenoprotein mRNAs. SelB conveys the Sec-tRNASec to the A site of the ribosome through binding to the SECIS mRNA hairpin adjacent to the UGA Sec codon. SelB is thus a bifunctional factor, carrying functional homology to elongation factor EF-Tu in its N-terminal domain and SECIS RNA binding activity via its C-terminal extension. In archaea and eukaryotes, selenocysteine incorporation exhibits a higher degree of complexity because the SECIS hairpin is localized in the 3' untranslated region of the mRNA. In the last couple of years, remarkable progress has been made toward understanding the underlying mechanism in mammals. Indeed, the discovery of the SECIS RNA binding protein SBP2, which is not a translation factor, paved the way for the subsequent isolation of mSelB/EFSec, the mammalian homolog of SelB. In contrast to the eubacterial SelB, the specialized elongation factor mSelB/EFSec the SECIS RNA binding function. The role is carried out by SBP2 that also forms a protein-protein complex with mSelB/EFSec. As a consequence, an important difference between the eubacterial and eukaryal selenoprotein synthesis machineries is that the functions of SelB are divided into two proteins in eukaryotes. Obviously, selenoprotein synthesis represents a higher degree of complexity than anticipated, and more needs to be discovered in eukaryotes. In this review, we will focus on the structural and functional aspects of the SelB and SBP2 factors in selenoprotein synthesis. 相似文献
87.
The chemical modification of ε-NH2 lysine residues of horseradish peroxidase (E.C. 1.11.1.7) with several mPEG was carried out. The modified enzymes were studied
through Chromatographic and electrophoretic methods; the extent of mPEG linking was determined using1H-NMR. Peroxidase, modified with mPEG ranging from 350 to 5000, activated with 4-nitrophenylchloroformate (mPEGpn), showed
a better thermal stability than the native, but there was no correlation between the length of the polymer adduct and the
improvement. The enzyme was modified with mPEG (5000) activated by cyanuric chloride (mPEGcc). The number of modified lysine
increased, but the thermal behavior of mPEGcc peroxidase was similar to those of mPEGpn enzymes. In all cases, the modification
did not markedly change the stability in organic solvents. 相似文献
88.
89.
A Boron‐Fluorinated Tris(pyrazolyl)borate Ligand (FTp*) and Its Mono‐ and Dinuclear Copper Complexes [Cu(FTp*)2] and [Cu2(FTp*)2]: Synthesis,Structures, and DFT Calculations 下载免费PDF全文
Dr. Timo Augenstein Franziska Dorner Kevin Reiter Hanna E. Wagner Dr. Delphine Garnier Prof. Dr. Wim Klopper Prof. Dr. Frank Breher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7935-7943
Reaction of [Si(3,5‐Me2pz)4] ( 1 ) with [Cu(MeCN)4][BF4] ( 2 ) gave the mono‐ and dinuclear copper complexes [Cu2(FTp*)2] ( 3 ) and [Cu(FTp*)2] ( 4 ). Both complexes contain the so‐far unprecedented boron‐fluorinated FTp* ligand ([FB(3,5‐Me2pz)3]? with pz=pyrazolyl) originating from 1 , acting as a pyrazolyl transfer reagent, and the [BF4]? counter anion of 2 , serving as the source of the {BF} entity. The solid‐state structures as well as the NMR and EPR spectroscopic characteristics of the complexes were elaborated. Pulsed gradient spin echo (PGSE) experiments revealed that 3 retains (almost entirely) its dimeric structure in benzene, whereas dimer cleavage and formation of acetonitrile adducts, presumably [Cu(FTp*)(MeCN)], is observed in acetonitrile. The short Cu???Cu distance of 269.16 pm in the solid‐state is predicted by DFT calculations to be dictated by dispersion interactions between all atoms in the complex (the Cu?Cu dispersion contribution itself is only very small). As revealed by cyclic voltammetry studies, 3 shows an irreversible (almost quasi‐reversible at higher scan rates) oxidation process centred at Epa=?0.23 V (E01/2=?0.27 V) (vs. Fc/Fc+). Oxidation reactions on a preparative scale with one equivalent of the ferrocenium salt [Fc][BF4] (very slow reaction) or air (fast reaction) furnished blue crystals of the mononuclear copper(II) complex [Cu(FTp*)2] ( 4 ). As expected for a Jahn–Teller‐active system, the coordination sphere around copper(II) is strongly distorted towards a stretched octahedron, in accordance with EPR spectroscopic findings. 相似文献
90.
Dr. Matthieu Fonvielle Dr. Inés Li de La Sierra‐Gallay Dr. Afaf H. El‐Sagheer Maxime Lecerf Delphine Patin Dr. Dénia Mellal Dr. Claudine Mayer Dr. Didier Blanot Dr. Nittaya Gale Dr. Tom Brown Dr. Herman van Tilbeurgh Dr. Mélanie Ethève‐Quelquejeu Dr. Michel Arthur 《Angewandte Chemie (International ed. in English)》2013,52(28):7278-7281