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1.
Roberto Morales-Cerrada Dr. Christophe Fliedel Dr. Jean-Claude Daran Dr. Florence Gayet Dr. Vincent Ladmiral Dr. Bruno Améduri Prof. Rinaldo Poli 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(1):296-308
Thermal decarbonylation of the acyl compounds [Mn(CO)5(CORF)] (RF=CF3, CHF2, CH2CF3, CF2CH3) yielded the corresponding alkyl derivatives [Mn(CO)5(RF)], some of which have not been previously reported. The compounds were fully characterized by analytical and spectroscopic methods and by several single-crystal X-ray diffraction studies. The solution-phase IR characterization in the CO stretching region, with the assistance of DFT calculations, has allowed the assignment of several weak bands to vibrations of the [Mn(12CO)4(eq-13CO)(RF)] and [Mn(12CO)4(ax-13CO)(RF)] isotopomers and a ranking of the RF donor power in the order CF3<CHF2<CH2CF3≈CF2CH3. The homolytic Mn−RF bond cleavage in [Mn(CO)5(RF)] at various temperatures under saturation conditions with trapping of the generated RF radicals by excess tris(trimethylsilyl)silane yielded activation parameters ΔH≠ and ΔS≠ that are believed to represent close estimates of the homolytic bond dissociation thermodynamic parameters. These values are in close agreement with those calculated in a recent DFT study (J. Organomet. Chem. 2018 , 864, 12–18). The ability of these complexes to undergo homolytic Mn−RF bond cleavage was further demonstrated by the observation that [Mn(CO)5(CF3)] (the compound with the strongest Mn−RF bond) initiated the radical polymerization of vinylidene fluoride (CH2=CF2) to produce poly(vinylidene fluoride) in good yields by either thermal (100 °C) or photochemical (UV or visible light) activation. 相似文献
2.
We define admissible quasi-Hopf quantized universal enveloping (QHQUE) algebras by ?-adic valuation conditions. We show that any QHQUE algebra is twist-equivalent to an admissible one. We prove a related statement: any associator is twist-equivalent to a Lie associator. We attach a quantized formal series algebra to each admissible QHQUE algebra and study the resulting Poisson algebras. 相似文献
3.
Tuomas Aitasalo Jorma Hls Hgne Jungner Jean-Claude Krupa Mika Lastusaari Janina Legendziewicz Janne Niittykoski 《Radiation measurements》2004,38(4-6):727-730
The UV excited and persistent luminescence properties as well as thermoluminescence (TL) of Eu2+ doped strontium aluminates, SrAl2O4:Eu2+ were studied at different temperatures. Two luminescence bands peaking at 445 and 520 nm were observed at 20 K but only the latter at 295 K. Both Sr-sites in the lattice are thus occupied by Eu2+ but at room temperature efficient energy transfer occurs between the two sites. The UV excited and persistent luminescence spectra were similar at 295 K but the excitation spectra were different. Thus the luminescent centre is the same in both phenomena but excitation processes are different. Two TL peaks were observed between 50 and 250 °C in the glow curve. Multiple traps were, however, observed by preheating and initial rise methods. With longer delay times only the high temperature TL peak was observed. The persistent luminescence is mainly due to slow fading of the low temperature TL peak but the step-wise feeding process from high temperature traps is also probable. 相似文献
4.
Peixiang Xing Gilles P. Robertson Michael D. Guiver Serguei D. Mikhailenko Serge Kaliaguine 《Journal of polymer science. Part A, Polymer chemistry》2004,42(12):2866-2876
A series of sulfonated poly(aryl ether ketone)s (SPAEKs) were prepared by aromatic nucleophilic polycondensation of 2,6‐dihydroxynaphthalene with 5,5′‐carbonyl‐bis(2‐fluorobenzenesulfonate) and 4,4′‐difluorobenzophenone. The structure and degree of sulfonation (DS) of the SPAEKs were characterized using 1H NMR spectroscopy. The experimentally observed DS values were close to the expected values derived from the starting material ratios. The thermal stabilities of the SPAEKs were characterized by thermogravimetric analysis, which showed that in acid and sodium salt forms they were thermally stable in air up to about 240 and 380 °C, respectively. Transparent membranes cast from the directly polymerized SPAEKs exhibited good mechanical properties in both dry and hydrated states. The dependence of water uptake and of membrane swelling on the DS at different temperatures was studied. SPAEK membranes with a DS from 0.72 to 1.60 maintained adequate mechanical properties after immersion in water at 80 °C for 24 h. The proton conductivity of SPAEK membranes with different degrees of sulfonation was measured as a function of temperature. The proton conductivity of the SPAEK films increased with increased DS, and the highest room temperature conductivity (4.2 × 10?2 S/cm) was recorded for a SPAEK membrane with a DS of 1.60, which further increased to 1.1 × 10?1 S/cm at 80 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2866–2876, 2004 相似文献
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6.
In order to replace silicones in some of their biomedical applications, e.g. syringe lubrication, implants ets., a series of digermoxanes (R1R2R3Ge)2O (R = n–alkyl, aryl) were synthesized. These compounds are thermally stable oils; their viscosities, depending on the nature of substituents, lie in the range 1–72 cPo (mPa s) at 20°C. 相似文献
7.
Anne Boutet De Monvel-Berthier Louis Boutet De Monvel Gilles Lebeau 《Journal d'Analyse Mathématique》1992,58(1):39-60
Sans résumé
Dedicated to Professor Shmuel Agmon 相似文献
8.
Communicated by Charles A. Micchelli. 相似文献
9.
Denis Prat Françoise Benedetti Lahlou Nait Bouda Gilles Franc Girard 《Tetrahedron letters》2004,45(4):765-768
An industrial synthesis of 11β-aryl-estrone derivatives is described, based on the 1,4-addition of the aryl side-chain, as a cuprate, on to a mixture of allylic 5(10) alpha and beta epoxides, followed by hydrolysis and subsequent aromatization. 相似文献
10.
Gilles Carron 《Journal of Functional Analysis》2004,212(1):222-260
We give a formula for the jump at zero of the spectral shift function associated with Schrödinger operator on manifolds with conical ends. We show that, according to its decay, a zero energy resonant state has a non-integer contribution. 相似文献