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151.
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153.
Philippe Pascal Gilbert Clouet Pascale Corpart Dominique Charmot 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7):1341-1351
Abstract Due to high chain transfer and the subsequent terminator properties of the dixanthogen moiety, (AB)n multiblock copolymers of poly(oxyethylene-block-methyl methacrylate) and ABA triblock copolymers of poly(methyl methacrylate-block-2-ethylhexyl acrylate) could be synthesized from dixanthogen-linked poly(oxyethylene) and poly(methyl methacrylate) pre-polymer sequences, respectively, using free-radical chemistry. A simple and efficient method was developed for the synthesis of dixanthogen-linked polymers: Hydroxyl-functionalized pre-polymers were reduced using NaH to form alkoxide; CS2 was then added to the alkoxide to form xanthate; and finally the xanthate was oxidized either in an aqueous or organic medium to form the dixanthogen. The synthesis techniques provided in this paper are general and thus, in principle, can be applied to many other block copolymer systems. 相似文献
154.
Dr. Julien Lieffrig Dr. Olivier Jeannin Arkadiusz Frąckowiak Dr. Iwona Olejniczak Roman Świetlik Dr. Slimane Dahaoui Dr. Emmanuel Aubert Prof. Dr. Enrique Espinosa Dr. Pascale Auban‐Senzier Dr. Marc Fourmigué 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):14804-14813
Charge‐assisted halogen bonding is unambiguously revealed from structural and electronic investigations of a series of isostructural charge‐transfer complexes derived from iodinated tetrathiafulvalene and tetracyanoquinodimethane derivatives, (EDT‐TTFI2)2(TCNQFn), n=0–2, which exhibit variable degrees of ionicity. The iodinated tetrathiafulvalene derivative, EDT‐TTFI2, associates with tetracyanoquinodimethane (TCNQ) and its derivatives of increasing reduction potential (TCNQF, TCNQF2) through highly directional C? I???N≡C halogen‐bond interactions. With the less oxidizing TCNQ acceptor, a neutral and insulating charge‐transfer complex is isolated whereas with the more oxidizing TCNQF2 acceptor, an ionic, highly conducting charge‐transfer salt is found, both of 2:1 stoichiometry and isostructural with the intermediate TCNQF complex, in which a neutral–ionic conversion takes place upon cooling. A correlation between the degree of charge transfer and the C? I???N≡C halogen‐bond strength is established from the comparison of the structures of the three isostructural complexes at temperatures from 300 to 20 K, thus demonstrating the importance of electrostatics in the halogen‐bonding interaction. The neutral–ionic conversion in (EDT‐TTFI2)2(TCNQF) is further investigated through the temperature dependence of its magnetic susceptibility and the stretching modes of the C≡N groups. 相似文献
155.
Laetitia Ancel Agnieszka Niedźwiecka Colette Lebrun Christelle Gateau Pascale Delangle 《Comptes Rendus Chimie》2013,16(6):515-523
Lanthanide-binding peptides are very attractive for the design of bioprobes. Indeed, they combine the amazing properties of lanthanide ions, such as their time-resolved luminescence (Eu, Tb) or electronic relaxation (Gd) to the characteristics of the peptide scaffold, such as large solubility in water and ability to recognize biological substrates. Peptides derived from natural amino acids are reviewed in a first section. Some of their lanthanide complexes have already demonstrated their efficiency in determining protein structures and functions. Then, we will show how insertion of chelating unnatural amino acids modulates peptide-lanthanide complexes properties, such as luminescence and stability. 相似文献
156.
Cedric Pardanaud Celine Martin Gilles Cartry Ahmad Ahmad Loic Schiesko Gregory Giacometti Marcel Carrere Pascale Roubin 《Journal of Raman spectroscopy : JRS》2015,46(2):256-265
Graphite samples exposed to H, D and He plasma at fluencies from 1016 to 1018 cm−2 have been investigated by means of atomic force and Raman microscopies. The ion energy was varied between 40 and 800 eV, and the ion incidence was either perpendicular (Highly Oriented Pyrolitic Graphite) or parallel (carbon/carbon composite) to the basal plane. When increasing the impinging ion energy, the growth of nanometric domes at the surface has been observed by atomic force microscopy and the incident kinetic energy has been found as the parameter determining their height. Two different Raman signatures related to (1) a graphitic nano‐crystalline component similar to that of a 1014 cm−2 bombarded 1‐, 2‐ and 3‐layer graphene, and to (2) an amorphous component, have been evidenced. Polarization studies have revealed that these components are related to regions with either in‐plane or out‐of‐plane disorder, coexisting in the material. These Raman studies have also revealed that both the defect–defect distance in the first case and the aromatic domain size in the second case are typically 1 nm. When the number of vacancies created in the material increases, the number of in‐plane defects decreases to the benefit of the out‐of‐plane defects. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
157.
R. Gaudiuso M. Dell’Aglio O. De Pascale S. Loperfido A. Mangone A. De Giacomo 《Analytica chimica acta》2014
A modified version of the calibration-free (CF) method was applied to the analysis of a set of archaeological brooches made of various copper-based alloys and coming from the archaeological site of Egnatia (Apulia, Southern Italy). The developed methodology consists in determining the plasma temperature by reversing the set of equations employed in the usual CF algorithm, and it is thus referred to as “inverse method”. The plasma temperature is determined for one certified standard, by using its known elemental composition as an input data, and then applied to the set of unknown samples to evaluate their composition in a CF mode. The feasibility of such an approach is demonstrated by comparing the results obtained with classical LIBS (drawing calibration lines with a series of matrix-matched certified standards) and with independent measurements performed with a conventional technique (LA-ICP-MS). 相似文献
158.
Concetta De Santi Pietro Tedesco Luca Ambrosino Bjørn Altermark Nils-Peder Willassen Donatella de Pascale 《Applied biochemistry and biotechnology》2014,172(6):3054-3068
The special features of cold-adapted lipolytic biocatalysts have made their use possible in several industrial applications. In fact, cold-active enzymes are known to be able to catalyze reactions at low temperatures, avoiding side reactions taking place at higher temperatures and preserving the integrity of products. A lipolytic gene was isolated from the Arctic marine bacterium Rhodococcus sp. AW25M09 and expressed in Escherichia coli as inclusion bodies. The recombinant enzyme (hereafter called RhLip) showed interesting cold-active esterase activity. The refolded purified enzyme displayed optimal activity at 30 °C and was cold-active with retention of 50 % activity at 10 °C. It is worth noting that the optimal pH was 11, and the low relative activity below pH 10 revealed that RhLip was an alkaliphilic esterase. The enzyme was active toward short-chain p-nitrophenyl esters (C2–C6), displaying optimal activity with the butyrate (C4) ester. In addition, the enzyme revealed a good organic solvent and salt tolerance. These features make this an interesting enzyme for exploitation in some industrial applications. 相似文献
159.
Leblanc N Mercier N Zorina L Simonov S Auban-Senzier P Pasquier C 《Journal of the American Chemical Society》2011,133(38):14924-14927
The search for hybrid organic-inorganic materials, which have the great advantage that they can be synthesized at moderate temperature (T < 200 °C), remains a great challenge in the field of ferroelectrics. Here, a room-temperature ferroelectric material with interesting characteristics, (MV)[BiI(3)Cl(2)] (MV(2+) = methylviologen), is reported. Its structure is based on polar inorganic chains resulting from a remarkable Cl/I segregation induced by methylviologen entities, which coincide with the fourfold polar axis of the tetragonal structure. Of great importance is that this room-temperature hybrid ferroelectric displays a clear electrical hysteresis loop with a large spontaneous polarization (>15 μC·cm(-2)). 相似文献
160.
Dr. Eric Gouré Dr. Frédéric Avenier Patrick Dubourdeaux Dr. Olivier Sénèque Dr. Florian Albrieux Colette Lebrun Dr. Martin Clémancey Dr. Pascale Maldivi Dr. Jean‐Marc Latour 《Angewandte Chemie (International ed. in English)》2014,53(6):1580-1584
Metal‐catalyzed nitrene transfer reactions arouse intense interest as clean and efficient procedures for amine synthesis. Efficient Rh‐ and Ru‐based catalysts exist but Fe alternatives are actively pursued. However, reactive iron imido species can be very short‐lived and getting evidence of their occurrence in efficient nitrene‐transfer reactions is an important challenge. We recently reported that a diiron(III,II) complex is a very efficient nitrene‐transfer catalyst to various substrates. We describe herein how, by combining desorption electrospray ionization mass spectrometry, quantitative chemical quench experiments, and DFT calculations, we obtained conclusive evidence for the occurrence of an {FeIIIFeIV?NTosyl} intermediate that is very active in H‐abstraction and nitrene‐transfer reactions. DFT calculations revealed a strong radical character of the tosyl nitrogen atom in very low‐lying electronic configurations of the FeIV ion which are likely to confer its high reactivity. 相似文献