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71.
New atom equivalents are introduced to convert BP/DN**//MMFF energies into formation enthalpies. As a result of using molecular mechanics structures, poor results are obtained for compounds outside the scope of the force field, such as those bearing NF2 groups or some nitrogenous systems. Notwithstanding these limitations, present procedures compare well with the results of previous atom equivalents schemes. Indeed, rms deviations from experiment are below 9 kJ/mol for hydrocarbons, and close to 16 kJ/mol for a variety of compounds reasonably well described by MMFF. The explicit inclusion of thermal and vibrational contributions, using calculated frequencies, does not improve the results. This study demonstrates that cost‐effective approaches to formation enthalpies may be developed on the basis of a combination of DFT with a suitable molecular mechanics force field. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 367–379, 2000 相似文献
72.
Bernold Hasenknopf Jean-Marie Lehn Nedjia Boumediene Emmanuelle Leize Alain Van Dorsselaer 《Angewandte Chemie (International ed. in English)》1998,37(23):3265-3268
NMR and MS analysis as a function of time has shown that the self-assembly of a linear ligand with Fe2+ or Ni2+, metal ions of octahedral coordination geometry, generates first a triple helicate and thereafter the circular helicate 1 as kinetic and thermodynamic products, respectively. The results provide insight into features of the energy hypersurface on which this self-assembly operates and point to the general role of kinetic and thermodynamic control in such processes. 相似文献
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The separation of diisopropylnaphthalenes was reinvestigated. The application of GC × GC appears to be a clear and necessary improvement over the use of single column techniques, with a polar (CP-Wax-52) column as reference technique, and a non-polar (CP-Sil-8) column as an alternative. Both qualitative and quantitative separations of DIPN isomers showed to be superior on GC × GC. The composition of both a DIPN mixture resulting from a typical experiment with a zeolite catalyst and a commercial one could be quantitatively determined in this way. 相似文献
76.
Emmanuelle Lipka Julie Charton Marie‐Pierre Vaccher Marcia Folly‐Klan Jean‐Paul Bonte Claude Vaccher 《Journal of separation science》2009,32(11):1907-1915
Baseline separation of 18 new substituted benzimidazole derivatives, potent AMP‐activated protein kinase (AMPK) activators, with one chiral center, was achieved by CD‐EKC using sulfated and highly sulfated CDs (SCDs and HS‐CDs) as chiral selectors. The influence of the type and concentration of the chiral selectors on the enantioseparations was investigated. The SCDs exhibit a very high enantioselectivity power since they allow excellent enantiomeric resolutions compared to those obtained with the neutral CDs. The enantiomers were resolved with analysis times around 6 min using 25 mM phosphate buffer at pH 2.5 containing either β‐S‐CD, HS‐β‐CD, HS‐γ‐CD (3 or 4% w/v) at 25°C, with a voltage of 20 kV. The apparent association constants of the inclusion complexes were calculated. The study of the solute structure‐enantioseparation relationships seems to show the high contribution of the interactions between the solutes phenyl ring and the CDs to the enantiorecognition process. The optimized method was briefly validated (LOD less than 1%) and the purity of enantiomers of compound 3 was determined. The enantiomer migration shows reversal order depending on the kind of CD. 相似文献
77.
Riegert D Collin J Meddour A Schulz E Trifonov A 《The Journal of organic chemistry》2006,71(6):2514-2517
Ytterbium and lutetium ionic complexes derived from enantiopure substituted (R)-binaphthylamine ligands, of the general formula [Li(THF)n][Ln[(R)-C20H12(NR)2]2], have been investigated for the hydroamination/cyclization of several aminopentenes and an aminohexene. Complexes with isopropyl or cyclohexyl substituents on nitrogen atoms were found to be efficient catalysts under mild conditions for the formation of N-containing heterocycles with enantiomeric excesses up to 78%. 相似文献
78.
Lasserre JP Beyne E Pyndiah S Lapaillerie D Claverol S Bonneu M 《Electrophoresis》2006,27(16):3306-3321
Study of the complexome - all the protein complexes of the cell - is essential for a better understanding and more global vision of cell function. Using two-dimensional blue native/SDS-PAGE (2-D BN/SDS-PAGE) technology, the cytosolic and membrane protein complexes of Escherichia coli were separated. Then, the different partners of each protein complex were identified by LC-MS/MS. In this report, 306 protein complexes were separated and identified. Among these protein complexes, 50 heteromultimeric and 256 homomultimeric protein complexes were found. Among the 50 heteromultimeric protein complexes, 18 previously described protein complexes validate the technology. In this study, 109 new protein complexes were found, providing insight into the function of previously uncharacterized bacterial proteins. 相似文献
79.
Vronique Sadtler Marianna Rondon‐Gonzalez Audrey Acrement Lionel Choplin Emmanuelle Marie 《Macromolecular rapid communications》2010,31(11):998-1002
This study reports the first PEO‐coated polymer nanoparticles synthesis by miniemulsion polymerization of nano‐emulsions prepared by the low‐energy emulsification method called EIP. The surfactant used was Brij 98, a PEO based non ionic commercial surfactant. The partial phase diagram of the system water/Brij 98/styrene was first determined. The Emulsion Inversion Point technique was then used on the water/Brij 98/styrene system to the formation of styrene‐in‐water nano‐emulsions. After miniemulsion polymerization, particle sizes as low as 36 nm were obtained. To the best of our knowledge, this method had not been used for polymerizable system up to now.
80.
Marie Labat Jean-Blaise Brubach Alessandra Ciavardini Marie-Emmanuelle Couprie Erik Elkaim Pierre Fertey Tom Ferte Philippe Hollander Nicolas Hubert Emmanuelle Jal Claire Laulhé Jan Luning Olivier Marcouillé Thierry Moreno Paul Morin Francois Polack Pascale Prigent Sylvain Ravy Jean-Paul Ricaud Pascale Roy Mathieu Silly Fausto Sirotti Amina Taleb Marie-Agnès Tordeux Amor Nadji 《Journal of synchrotron radiation》2018,25(2):385-398
The investigation of ultrafast dynamics, taking place on the few to sub‐picosecond time scale, is today a very active research area pursued in a variety of scientific domains. With the recent advent of X‐ray free‐electron lasers (XFELs), providing very intense X‐ray pulses of duration as short as a few femtoseconds, this research field has gained further momentum. As a consequence, the demand for access strongly exceeds the capacity of the very few XFEL facilities existing worldwide. This situation motivates the development of alternative sub‐picosecond pulsed X‐ray sources among which femtoslicing facilities at synchrotron radiation storage rings are standing out due to their tunability over an extended photon energy range and their high stability. Following the success of the femtoslicing installations at ALS, BESSY‐II, SLS and UVSOR, SOLEIL decided to implement a femtoslicing facility. Several challenges were faced, including operation at the highest electron beam energy ever, and achievement of slice separation exclusively with the natural dispersion function of the storage ring. SOLEIL's setup also enables, for the first time, delivering sub‐picosecond pulses simultaneously to several beamlines. This last feature enlarges the experimental capabilities of the facility, which covers the soft and hard X‐ray photon energy range. In this paper, the commissioning of this original femtoslicing facility is reported. Furthermore, it is shown that the slicing‐induced THz signal can be used to derive a quantitative estimate for the degree of energy exchange between the femtosecond infrared laser pulse and the circulating electron bunch. 相似文献