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1.
A. Zarrouk I. El Ouali M. Bouachrine B. Hammouti Y. Ramli E. M. Essassi I. Warad A. Aouniti R. Salghi 《Research on Chemical Intermediates》2013,39(3):1125-1133
Corrosion inhibition efficiencies of 1,4-dihydroquinoxaline-2,3-dione (Q1) and 2-phenylthieno[2,3-b]quinoxaline (Q2) as corrosion inhibitors against the corrosion of steel surface in hydrochloric acid is studied by means of density functional approach B3LYP/6-31G calculations. Quantum chemical parameters such as highest occupied molecular orbital energy (E HOMO), lowest unoccupied molecular orbital energy (E LUMO), energy gap (ΔE), dipole moment (μ), electronegativity (χ), electron affinity (A), global hardness (η), softness (σ), ionization potential (I), the fraction of electrons transferred (?N), the global electrophilicity ω, and the total energy were calculated. All calculations have been performed by considering density functional theory using the GAUSSIAN03W suite of programs. 相似文献
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Damien Berthier Alain Trachsel Charles Fehr Lahoussine Ouali Andreas Herrmann 《Helvetica chimica acta》2005,88(12):3089-3108
Amphiphilic polystyrene‐ and polymethacrylate‐based β‐acyloxy ketones were investigated as potential delivery systems for the controlled release of damascones by retro‐1,4‐addition in applications of functional perfumery. A series of random copolymers being composed of the hydrophobic damascone‐release unit and a second hydrophilic monomer were obtained by radical polymerization in organic solution by using 2,2′‐azobis[2‐methylpropanenitrile] (AIBN) as the radical source (Schemes 2 and 3). A first evaluation of the polymer conjugates in acidic or alkaline buffered aqueous solution, and in the presence of a surfactant, showed that polymethacrylates and polystyrenes having a carboxylic acid function as hydrophilic group are particularly interesting for the targeted applications (Table 2). The release of δ‐damascone ( 1 ) from polymers with poly(methacrylic acid) and poly(vinylbenzoic acid) comonomers in different stoichiometric ratios was thus followed over several days at pH 4, 7, and 9 by comparison of fluorescence probing, solvent extraction, and particle‐size measurements (Tables 3 and 4). In acidic media, the polymers were found to be stable, and almost no δ‐damascone ( 1 ) was released. In neutral or alkaline solution, where the carboxylic acid functions are deprotonated, the concentration of 1 increased over time. In the case of the polymethacrylates, the fluorescence probing experiments showed an increasing hydrophilicity of the polymer backbone with increasing fragrance release, whereas in the case of the polystyrene support, the hydrophilicity of the environment remained constant. These results suggest that the nature of the polymer backbone may have a stronger influence on the fragrance release than the ratio of hydrophilic and hydrophobic monomers in the polymer chain. 相似文献
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Ouali N Bocquet B Rigault S Morgantini PY Weber J Piguet C 《Inorganic chemistry》2002,41(6):1436-1445
Variable-temperature (1)H and (13)C NMR measurements of the D(3)-symmetrical triple-helical complexes [Ln(L1-2H)(3)](3)(-) (L1 = pyridine-2,6-dicarboxylic acid; Ln = La-Lu) show evidence of dynamic intermolecular ligand-exchange processes whose activation energies depend on the size of the metal ion. At 298 K, the use of diastereotopic probes in [Ln(L3-2H)(3)](3)(-) (L3 = 4-ethyl-pyridine-2,6-dicarboxylic acid) shows that fast intramolecular P <==> M interconversion between the helical enantiomers occurs on the NMR time scale. Detailed analyses of the paramagnetic NMR hyperfine shifts according to crystal-field independent techniques demonstrate the existence of two different helical structures, one for large lanthanides (Ln = La-Eu) and one for small lanthanides (Ln = Tb-Lu), in complete contrast with the isostructurality proposed 25 years ago. A careful reconsideration of the original crystal-field-dependent analysis shows that an abrupt variation of the axial crystal-field parameter A(0)2 parallels the structural change leading to some accidental compensation effects that prevent the detection of structural variations according to the classical one-nucleus method. Crystal structures in the solid state and density functional theory calculations in the gas phase provide structural models that rationalize the paramagnetic NMR data. A regular triple-helical structure is found for small lanthanides (Ln = Tb-Lu) in which the terdentate chelating ligands are rigidly tricoordinated to the metals. A flexible and distorted structure is evidenced for Ln = La-Eu in which the central pyridine rings interact poorly with the metal ion. The origin of the simultaneous variation of structural parameters and crystal-field and hyperfine constants near the middle of the lanthanide series is discussed together with the use of crystal-field-independent techniques for the interpretation of paramagnetic NMR spectra in axial lanthanide complexes. 相似文献
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Floquet S Ouali N Bocquet B Bernardinelli G Imbert D Bünzli JC Hopfgartner G Piguet C 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(8):1860-1875
The segmental tris-tridentate ligand L7 reacts with stoichiometric quantities of Ln(III) (Ln=La-Lu) in acetonitrile to give the complexes [Ln(2)(L7)(3)](6+) and [Ln(3)(L7)(3)](9+). Formation constants point to negligible size-discriminating effects along the lanthanide series, but Scatchard plots suggest that the self-assembly of the trimetallic triple-stranded helicates [Ln(3)(L7)(3)](9+) is driven to completion by positive cooperativity, despite strong intermetallic electrostatic repulsions. Crystallization provides quantitatively [Ln(3)(L7)(3)](CF(3)SO(3))(9) (Ln=La, Eu, Gd, Tb, Lu) and the X-ray crystal structure of [Eu(3)(L7)(3)](CF(3)SO(3))(9).(CH(3)CN)(9).(H(2)O)(2) (Eu(3)C(216)H(226)N(48)O(35)F(27)S(9), triclinic, P1, Z=2) shows the three ligand strands wrapped around a pseudo-threefold axis defined by the three metal ions rigidly held at about 9 A. Each metal ion is coordinated by nine donor atoms in a pseudo-trigonal prismatic arrangement, but the existence of terminal carboxamide units in the ligand strands differentiates the electronic properties of the terminal and the central metallic sites. Photophysical data confirm that the three coordination sites possess comparable pseudo-trigonal symmetries in the solid state and in solution. High-resolution luminescence analyses evidence a low-lying LMCT state affecting the central EuN(9) site, so that multi-metal-centered luminescence is essentially dominated by the emission from the two terminal EuN(6)O(3) sites in [Eu(3)(L7)(3)](9+). New multicenter equations have been developed for investigating the solution structure of [Ln(3)(L7)(3)](9+) by paramagnetic NMR spectroscopy and linear correlations for Ln=Ce-Tb imply isostructurality for these larger lanthanides. NMR spectra point to the triple helical structure being maintained in solution, but an inversion of the magnitude of the second-rank crystal-field parameters, obtained by LIS analysis, for the LnN(6)O(3) and LnN(9) sites with respect to the parameters extracted for Eu(III) from luminescence data, suggests that the geometry of the central LnN(9) site is somewhat relaxed in solution. 相似文献
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Anne-Marie Caminade Régis Laurent Cédric-Olivier Turrin Cyrille Rebout Béatrice Delavaux-Nicot Armelle Ouali Maria Zablocka Jean-Pierre Majoral 《Comptes Rendus Chimie》2010,13(8-9):1006-1027
This review emphasizes the role of phosphorus for the elaboration of dendrimers and of various highly sophisticated dendritic structures, and the invaluable role played by 31P NMR for their characterization and to ascertain their purity. A few properties, highlighting the importance of phosphorus are reported at the end of this review. 相似文献
7.
L. Ouali S. Stoll E. Pefferkorn A. Elaissari V. Lanet C. Pichot B. Mandrand 《先进技术聚合物》1995,6(7):541-546
The paper describes a study of the kinetics and mechanism of the coagulation of two types of immunoassays using sensitized latexes. The positive response to the first test is based on the aggregation of the gamma globulin (IgG)-coated polystyrene latexes in the presence of IgM rheumatoid antigen. The second test is relative to the heteroaggregation of two types of sensitized latexes induced by the presence of human chorionic gonadotropin (HCG). In the latter test, two identical polystyrene latexes bearing carboxylic acid surface groups were sensitized by covalent coupling of monoclonal antibodies specific for the αHCG determinant on one type of latex and for the βHCG determinant on the other type. Using the Coulter Counter method, the aggregate size distribution c(n) was determined as a function of the number n of elementary constituents, thus enabling calculation of the number N(t) and weight S(t) average sizes of the aggregates. The temporal variations of the average sizes were compared with typical situtions of reaction-limited aggregation processes in order to characterize the mechanism of aggregation induced by antibody–antigen reactions. 相似文献
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Nadjet Abada Ravi P. Agarwal Mouffak Benchohra Hadda Hammouche 《Applications of Mathematics》2011,56(2):227-250
In this paper we establish sufficient conditions for the existence of mild solutions and extremal mild solutions for some
densely defined impulsive semilinear neutral functional differential inclusions in separable Banach spaces. We rely on a fixed
point theorem for the sum of completely continuous and contraction operators. 相似文献
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Nadjet Abada Mouffak Benchohra Hadda Hammouche 《Nonlinear Analysis: Hybrid Systems》2010,4(4):791-803
In this paper, we shall establish sufficient conditions for the existence of integral solutions for some nondensely defined impulsive semilinear functional differential inclusions with state-dependent delay in separable Banach spaces. We shall rely on a fixed point theorem for the sum of completely continuous and contraction operators. 相似文献