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1.
R. Chitra Pascal Roussel R. R. Choudhury 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(9):o547-o549
The title complex, 2CH4N2S·C4H6O4, is a host–guest system. The asymmetric unit consists of one complete thiourea molecule and one‐half of a dimethyl oxalate molecule lying on an inversion centre. The host thiourea molecules are connected to form zigzag chains by N—H⋯S hydrogen bonds. The guest dimethyl oxalate molecules provide O‐atom acceptors for N—H⋯O hydrogen bonds, thus interconnecting the chains of thiourea molecules to form completely connected sheets. The reduction in temperature from 300 to 100 K leaves the structure unchanged and still isostructural with that previously determined for the analogous thiourea–diethyl oxalate (2/1) complex. It does, however, induce closer packing of the molecules, general shrinkage of the unit cell and shortening of the hydrogen bonds, these last two to the extent of 1–2%. 相似文献
2.
Christophe Roussel Loc Dayon Henrik Jensen Hubert H. Girault 《Journal of Electroanalytical Chemistry》2004,570(2):187-199
A series of electrogenerated selective electrophiles based on substituted benzoquinones has been characterized as tags for l-cysteine and cysteine residues in proteins. The electrophiles are generated electrochemically from the corresponding hydroquinones. It is shown from mass spectrometry analysis that the electrogenerated benzoquinone can tag the biomolecules. The rate constants pertaining to the addition of l-cysteine onto the electrogenerated benzoquinones have been determined using electrochemical techniques. The substitution patterns have been unraveled leading to the assessment of site-specific rate constants. It is shown that the rate constants are primarily dependent on the electronic nature of the substituents as expressed by the Hammett substitution constant. The apparent tagging yields observed for l-cysteine in nanospray mass spectrometry experiments do not correspond to the yields expected from the electrochemical study, as the ionisation efficiencies are highly dependent on the tag. Finally, the on-line tagging has been tested using β-lactoglobulin A and myoglobin. Based on these results, it is concluded that the tagging reaction is selective towards cysteine when it takes place in the nanospray interface. The results show that the methodology presented can be used for a rapid characterization and identification of reactive sites in biomolecules. 相似文献
3.
Marc Visseaux Mickael Terrier Andr Mortreux Pascal Roussel 《Comptes Rendus Chimie》2007,10(12):1195-1199
The reaction of one equivalent of Nd(BH4)3(THF)3 with an half equivalent of dialkylmagnesium in the presence of a stoichiometric amount of pentamethylcyclopentadiene cleanly affords a new kind of half-sandwich of neodymium that is stable toward comproportionation. This strategy can be advantageously applied to generate in situ catalysts allowing the controlled polymerisation of isoprene. 相似文献
4.
H. Frunder D. Illig H. Finsterhölzl H.W. Schrōtter B. Lavorel G. Roussel J.C. Hilico J.P. Champion G. Pierre G. Poussigue E. Pascaud 《Chemical physics letters》1983,100(1):110-114
The CARS spectrum of the v1 band of 12CH4 at a pressure of 14 mbar was recorded using cw excitation in the cavity of a ring argon ion laser. The analysis of the intensity profile of the obarred spectrum led to the detection of inconsistencies with the hitherto proposed calculated positions of transitions with J = 7 to J = 10 and to a relocation of the corresponding lines. 相似文献
5.
We have accomplished the intramolecular oxymercuration of γ-δ ethylenic alcohols, with different mercuric salts under different conditions. By “in situ” reduction, or by direct reduction of isolated mercuric compounds, we obtain, in some cases, diastereoisomers with different relative yields. 相似文献
6.
We study methods for reducing chemical master equations using the Michaelis-Menten mechanism as an example. The master equation consists of a set of linear ordinary differential equations whose variables are probabilities that the realizable states exist. For a master equation with s(0) initial substrate molecules and e(0) initial enzyme molecules, the manifold can be parametrized by s(0) of the probability variables. Fraser's functional iteration method is found to be difficult to use for master equations of high dimension. Building on the insights gained from Fraser's method, techniques are developed to produce s(0)-dimensional manifolds of larger systems directly from the eigenvectors. We also develop a simple, but surprisingly effective way to generate initial conditions for the reduced models. 相似文献
7.
An improved methodology for microbatch screening in the liquid-solid enantioselective adsorption of racemates by solid chiral selector is presented and illustrated by the evaluation of a series of six cellulose tris(alpha-phenylpropionate) presenting a configurational diversity and cellulose tris (4-methylbenzoate). Analyses were performed on 5 mg scale of chiral selector and 150 microL of supernatant containing a mixture of three test-racemates. Fifteen test-racemates were chosen according to their molecular diversity using a hierarchical clustering approach for seven selected three-dimensional molecular properties. The 15 racemates were sorted in five test mixtures composed of three racemates each according to the following constraints: each triplet of test-racemates can be analyzed without peak overlap on a commercially available chiral stationary phase (CSP). The designed five groups of three racemates may be used for the evaluation of other chiral selectors in view of the preparation of CSPs. This methodology improves the throughput of the evaluation and could be automated. 相似文献
8.
Christian Roussel Alexandru T. Balaban Ulf Berg Michel Chanon Roger Gallo Gerd Klatte Joseph A. Memiaghe Jacques Metzger Daniela Oniciu Johanna Pierrot-Sanders 《Tetrahedron》1983,39(24):4209-4219
The effect of the shape of a methyl group on reactivity, which cannot be accounted for by considering a methyl group as a spherical substituent with the appropriate van der Waals radius, was considered in kinetics of alkylalion of substituted pyridines and barriers to rotation and ground state conformations of an isopropyl group attached to a planar framework. The perturbation of a methyl group by an o-methyl group is accounted for by a unique conformational explanation which involves the polyhedral shape of the methyl group. 相似文献
9.
Bimetallic Gold(I) Complexes with Ethynyl‐Helicene and Bis‐Phosphole Ligands: Understanding the Role of Aurophilic Interactions in their Chiroptical Properties 下载免费PDF全文
Dr. Mehdi El Sayed Moussa Dr. Hui Chen Zuoyong Wang Dr. Monika Srebro‐Hooper Dr. Nicolas Vanthuyne Dr. Soizic Chevance Prof. Christian Roussel Prof. J. A. Gareth Williams Prof. Jochen Autschbach Prof. Régis Réau Prof. Zheng Duan Dr. Christophe Lescop Dr. Jeanne Crassous 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(17):6075-6086
Monometallic gold(I)‐alkynyl‐helicene complexes ( 1 a , b ) and bimetallic gold(I)‐alkynyl‐helicene architectures featuring the presence ( 2 a , b ) or absence ( 3 a , b ) of aurophilic intramolecular interactions were prepared by using different types of phosphole ligands (mono‐phosphole L1 or bis‐phospholes L2 , 3 ). The influence of the AuI d10 metal center(s) on the electronic, photophysical, and chiroptical properties of these unprecedented phosphole‐gold(I)‐alkynyl‐helicene complexes was examined. Experimental and theoretical results highlight the importance of ligand‐to‐ligand‐type charge transfers and the strong effect of the presence or absence of AuI–AuI interactions in 2 a , b . 相似文献
10.
Hong Sun Frederick Roussel Wing Shun Cheung B. M. Fung Sandy S. Keast Mark Lohman 《Liquid crystals》2013,40(10):1483-1486
Liquid crystals (LCs) with diazo linkages have high dielectric and optical anisotropy. Two newly synthesized liquid crystalline compounds were dissolved in room temperature LC hosts, E7 and PTTP-24/36, to assess their properties. It was found that these mixtures have higher birefringence, larger dielectric anisotropy, and better elastic properties than the hosts. Satisfactory viscoelastic coefficients were also obtained for these mixtures, showing that they are promising LC materials for applications in the near IR region. 相似文献