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511.
Yannick Tauran Moez Rhimi Ryohei Ueno Marie Grosso Arnaud Brioude Erwann Janneau Kinga Suwinska Rima Kassab Patrick Shahgaldian Alessandro Cumbo Bernard Fenet Beomjoon Kim Anthony W. Coleman 《Journal of inclusion phenomena and macrocyclic chemistry》2013,77(1-4):213-221
The molecular recognition by para-sulphonato-calix[4]arene of cytosine, occurs in solution, in the solid-state and by assembly on the surface of para-sulphonato-calix[4]arene capped silver nanoparticles. Each of these states shows different modes of assembly; in solution a 1:1 complex is formed; in the solid state a 4:1 assembly exists, however some of the cytosine molecules are present as space fillers and do not participate in the host (guest complexes, finally on the surface of the hybrid silver/para-sulphonato-calix[4]arene nanoparticles a 2:1 cytosine/para-sulphonato-calix[4]arene assembly is observed. The assembly processes have been studied by DOSY NMR, fluorescence spectroscopy, Dynamic Light Scattering (DLS), Single Crystal Solid State Diffraction, Visible Spectroscopy and Electron Microscopy. The results demonstrate how cytosine initiates the aggregation of the hybrid silver/para-sulphonato-calix[4]arene hybrid nanoparticles. 相似文献
512.
Yannick Schildberg Johan Sjöblom Alfred A. Christy Jean-Luc Volle Odile Rambeau 《Journal of Dispersion Science and Technology》2013,34(7):575-605
Natural surfactants from four crude oils have been extracted by adsorption on silica after precipitation of the asphaltenes by means of centrifugation or decantation. The extracted fractions have been characterized, analytically by FT-IR spectroscopy (chemical functions) and chromatography (molecular weight and polarity) and by their interfacial properties with emulsification and interfacial tension measurements on the model system water/decane with interfacially active fractions in different concentrations. The importance of these fractions (precipitated and adsorbed) on the stability of w/o emulsions is investigated. The influence of some extraction parameters (centrifugation or decantation, different adsorbents) on the nature and the emulsion behaviour of the fractions is studied and shows that the classification of the surfactants (asphaltenes, resins) is diffuse. It also shows that all the interfacially active constituents of the crude are interacting and are involved in the interfacial processes. 相似文献
513.
Yannick Ortin 《合成通讯》2013,43(10):1404-1412
Purification of the hydrophobic extracts of the flowers and seed pods of Impatiens glandulifera(Himilayan balsam) yielded 2-methoxy-[1,4]-naphthoquinone 1, 1-hydroxyeicosan-3-one 16, and an unusual unsaturated fatty acid, trans-tetradec-2-enoic acid 6. Mass spectrometry and nuclear magnetic resonance spectroscopy indicated that the latter compound (6) was isolated as a mixture with linolenic acid 8 and saturated acids 7, 9, and 10 (chain lengths C-16, 18, and 20). Its structure was subsequently proven by independent chemical synthesis. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献
514.
Rettenmeier E Tokarev A Blanc C Dieudonné P Guari Y Hesemann P 《Journal of colloid and interface science》2011,356(2):639-646
We report the synthesis of novel chiral catanionic liquid crystals bearing camphorsulfonamide substructures. The phase behaviour of these long-chain substituted imidazolium sulphates and sulfonates was investigated using X-ray diffraction (XRD), polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). We observed that the phase behaviour clearly depends on the substitution of both cation and anion. The chiral camphorsulfonamide substructures have an unfavourable influence on the formation of liquid crystalline (LC-) phases. Contrary to N,N'-di-alkyl-imidazolium salts, the formation of LC phases was only observed when both cation and anion are substituted with long alkyl chains (C(12) or C(16)). Furthermore, the phase transition temperatures depend on the chain length of the alkyl groups, as higher phase transition temperatures were observed for compounds bearing longer alkyl chains. However, no macroscopic evidence for the formation of chiral mesophases was obtained. 相似文献
515.
Beniazza R Desvergnes V Mehta G Blanchard N Robert F Landais Y 《The Journal of organic chemistry》2011,76(3):791-799
A short access to homocalystegine analogues silylated at C7 is described. The synthesis involves the desymmetrization of a (phenyldimethylsilyl)methylcycloheptatriene using osmium-mediated dihydroxylation, followed by the diol protection and a cycloaddition involving the remaining diene moiety and an acylnitroso reagent. Additions of the osmium and acylnitroso reagents were shown, through X-ray diffraction studies of the resulting major isomers, to occur anti and syn, respectively, relative to the SiCH(2) substituent. N-O bond cleavage on the resulting cycloadduct then produces the aminopolyol having a silylmethyl substituent. Oxidation of the C-Si bond also afforded an access to unusual amino-heptitols having five contiguous stereogenic centers. In the course of this work, we finally observed a unusual rearrangement taking place on cycloheptanone 18 substituted by two acetyl groups and a neighboring Boc-protected amine. A profound reorganization of the substituents on the seven-membered ring effectively took place under acidic conditions (TFA) leading to the thermodynamically more stable homocalystegine-type compound. DFT calculations of the conformational energy of isomeric silyl homocalystegines indicated that the product observed upon the acid-mediated rearrangement was the most stable of a series of analogues with various distributions of substituents along the seven-membered ring backbone. A tentative mechanism is proposed to rationalize the acetate migrations and inversions of the stereochemistry at various stereocenters. 相似文献
516.
Sana Hraiech Anis Jouini Kyoung Jin Kim Yannick Guyot Akira Yoshikawa Georges Boulon 《Radiation measurements》2010,45(3-6):323-327
Yb3+ and M+ monovalent alkali ions (M+ = Li+, Na+, K+)-co-doped CaF2 cubic laser crystals were grown by the micro-pulling-down method (μ-PD) under CF4 atmosphere. Structural and spectroscopic characterizations of Yb3+ in substitution of Ca2+ (absorption, emission and decay curves) were carried out to study the effect of M+ ions as charge compensators. 相似文献
517.
Clment Kotras Maxime Leclercq Maxime Roger Camille Bouillon Antonio Recupido Aurlien Lebrun Yannick Bessin Philippe Gerbier Sbastien Richeter Sbastien Ulrich Sbastien Clment Mathieu Surin 《Molecules (Basel, Switzerland)》2022,27(19)
Dynamic covalent polymers (DCPs) offer opportunities as adaptive materials of particular interest for targeting, sensing and delivery of biological molecules. In this view, combining cationic units and fluorescent units along DCP chains is attractive for achieving optical probes for the recognition and delivery of nucleic acids. Here, we report on the design of acylhydrazone-based DCPs combining cationic arginine units with π-conjugated fluorescent moieties based on thiophene-ethynyl-fluorene cores. Two types of fluorescent building blocks bearing neutral or cationic side groups on the fluorene moiety are considered in order to assess the role of the number of cationic units on complexation with DNA. The (chir)optical properties of the building blocks, the DCPs, and their complexes with several types of DNA are explored, providing details on the formation of supramolecular complexes and on their stability in aqueous solutions. The DNA-templated formation of DCPs is demonstrated, which provides new perspectives on the assembly of fluorescent DCP based on the nucleic acid structure. 相似文献
518.
519.
520.
Dr. Conor T. Kelly Sean Dunne Dr. Irina A. Kühne Dr. Andrew Barker Dr. Kane Esien Dr. Solveig Felton Dr. Helge Müller-Bunz Dr. Yannick Ortin Prof. Grace G. Morgan 《Angewandte Chemie (International ed. in English)》2023,62(18):e202217388
Reversible proton-induced spin state switching of an FeIII complex in solution is observed at room temperature. A reversible magnetic response was detected in the complex, [FeIII(sal2323)]ClO4 ( 1 ), using Evans’ method 1H NMR spectroscopy which indicated cumulative switching from low-spin to high-spin upon addition of one and two equivalents of acid. Infrared spectroscopy suggests a coordination-induced spin state switching (CISSS) effect, whereby protonation displaces the metal-phenoxo donors. The analogous complex, [FeIII(4-NEt2-sal2323)]ClO4 ( 2 ), with a diethylamino group on the ligand, was used to combine the magnetic change with a colorimetric response. Comparison of the protonation responses of 1 and 2 reveals that the magnetic switching is caused by perturbation of the immediate coordination sphere of the complex. These complexes constitute a new class of analyte sensor which operate by magneto-modulation, and in the case of 2 , also yield a colorimetric response. 相似文献