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61.
Peyman Mohammadzadeh Jahani Alireza Nowroozi 《International journal of quantum chemistry》2013,113(7):1026-1033
HF, B3LYP, and MP2 methods with the standard basis set, 6‐311++G(d,p), were used to study various aspects of dinitrosamine. These results were compared with the outcomes of G2 and CBS‐QB3 methods. First, the conformational analysis and characterization of equilibrium conformations, especially global minima, were performed. On the basis of relative energies, we found that the dinitroso tautomers are more stable than the nitroso‐hydroxy (NH) ones. This preference is well‐interpreted in terms of tautomerization process and nitrosamine resonance. Furthermore, the nature of O? H···O intramolecular hydrogen bond (IMHB), in chelated forms of NH (NH‐11 and NH‐13) was comprehensively studied to evaluate the effect of hetero atoms (N) on the characteristic of IMHB systems. According to the results of isodesmic reaction method, the hydrogen bond energy of NH‐11 is greater than the malonaldehyde (MA) and NH‐13, whereas the electron density analysis and energy‐geometry correlation methods clearly predict that the hydrogen bond of NH‐11 is weaker than the MA. Additionally, the geometrical, atoms in molecules (AIM) and natural bond orbital's (NBO) parameters also emphasize on the MA as a chelated form with the strongest hydrogen bond. Finally, the solvent effects on the relative stability of selected dinitrosamine conformers are evaluated by different continuum (polarizable‐continuum model, isodensity polarizable continuum model, and self‐consistent isodensity polarizable continuum model), discrete and mixed solvent models. Theoretical results readily show that the potential energy surface of dinitrosamine, especially global minima, is strongly affected by the solvent. © 2012 Wiley Periodicals, Inc. 相似文献
62.
63.
Thomas R. Stengle Saeed M. Hosseini Hosein G. Basiri Kenneth L. Williamson 《Journal of solution chemistry》1984,13(11):779-787
The chemical shift of elemental xenon in solution is sensitive to the environment. The shift arises from van der Waals interactions in most liquids, but an additional effect is present in aqueous media yielding a larger shift than expected. In water the shift is affected by the presence of low molecular weight amphiphiles, and its variation with composition can reveal the presence of hydrophobic hydration of the amphiphile. The results are similar to the conclusions drawn from other physical studies. Data are presented for aqueous solutions of methanol, ethanol, n-propanol, iso-propanol, tert-butanol, dimethylsulfoxide, p-dioxane, and acetonitrile. 相似文献
64.
A novel and simple synthesis of 3-aroyl-2,5-diaryl-2,4-cyclopentadiene-1,1-dicarbonitriles is described. The reactive 1:1 zwitterionic intermediate, formed by the addition of triphenylphosphine to diaroylacetylenes, was trapped by arylidenemalononitriles to produce the title compounds under mild reaction conditions in fairly good yields. 相似文献
65.
Ordered ZnS-based colloidal crystals from homogeneous, core-shell, and hollow building blocks were prepared via electrosteric colloid stabilization combined with a convective assembly technique. The polyelectrolyte stabilized colloids assembled into face-centered cubic arrays with the (111) face perpendicular to the substrate. Structure-property correlations were made using scanning electron microscopy, scanning transmission electron microscopy, and UV/visible/near-IR spectroscopy. Multilayer film growth, with film thickness of several micrometers, was achieved. Optical spectra showed (111) stopgaps along with pronounced higher order peaks. The spectral position of the photonic stopgap can be predicted using a volume average refractive index and the Maxwell-Garnett formula for the homogeneous and core-shell particles, respectively. This work holds the promise of harnessing ZnS for optical property engineering and enhanced photonic band gap materials. 相似文献
66.
The main aim of this article is to study quantitative structure of small Ree Groups 2G2(q). Here, we prove that small Ree groups are uniquely determined by their orders and the set of the number of elements of the same order. 相似文献
67.
68.
Saeed Mohammadzadeh Manie Sangtarashha Habibollah Molatefi 《Archive of Applied Mechanics (Ingenieur Archiv)》2011,81(11):1621-1637
Track irregularities have a dramatic impact on the response and vibration of a railway vehicle and on the interaction between
wheel and rail. The random nature of the track structure and constituent materials and the effects of other factors such as
maintenance conditions and transit traffic give rise to the random nature of track irregularities. This research provides
a method to estimate the derailment probability of a railway vehicle where track irregularities are assumed to be random,
and the interaction of the track and the moving train is considered using advanced dynamic analysis. For this purpose, the
limit state function of derailment was estimated using the response surface method and advanced simulation. The probability
of derailment was then estimated using a Level 3 reliability method. 相似文献
69.
The reaction of perfluoroalkyl Grignard reagents with phosphorus(III) halides was explored. In the process a new convenient, one-pot, high yield method for the synthesis of (perfluoroalkyl)phosphonic acids has been developed. Perfluoroalkyl Grignard reagents react with phosphorus trichloride or phosphorus tribromide to form (perfluoroalkyl)phosphonous dihalides. Hydrolysis gives the corresponding (perfluoroalkyl)phosphonous acids. Oxidation of the phosphonous acids with H(2)O(2) produces (perfluoroalkyl)phosphonic acids in 60-78% overall yields, based on the corresponding perfluoroalkyl iodide. The X-ray crystal structures of the toluidinium salts, [MeC(6)H(4)NH(3)](2)[C(2)F(5)PO(3)] and [MeC(6)H(4)NH(3)][C(8)F(17)P(O)(2)OH], are reported. 相似文献
70.
Gholamhossein Rounaghi Massoumeh Mohajeri Zahra Atashi Roya Mohammadzadeh kakhki 《Journal of inclusion phenomena and macrocyclic chemistry》2012,73(1-4):435-441
The stability constants (Kf) for the complexation reactions of Cr3+, Mn2+ and Zn2+ metal cations with macrocyclic ligand, 15-crown-5 (15C5), in acetonitrile (AN), ethanol (EtOH) and also in their binary solutions (AN–EtOH) were determined at different temperatures, using conductometric method. 15C5 forms 1:1 complexes with Cr3+, Mn2+ and Zn2+ cations in solutions. A non-linear behaviour was observed for changes of logKf of the metal ion complexes versus the composition of the mixed solvent. The order of stability of the metal–ion complexes in pure AN and in a binary solution of AN–EtOH (mol% AN?=?52) at 25?°C was found to be: (15C5Zn)2+?>?(15C5·Mn)2+?>?(15C5·Cr)3+, but in the case of pure EtOH at the same temperature, it changes to: (15C5·Zn)2+?>?(15C5·Cr)3+?>?(15C5·Mn)2+. The results also show that the stability sequence of the complexes in the other binary solutions of AN–EtOH (mol% AN?=?26 and mol% AN?=?76) varies in order: (15C5·Cr)3+?~?(15C5·Zn)2+?>?(15C5·Mn)2+. The values of the standard thermodynamic quantities (ΔHC°, ΔSC°) for formation of (15C15-Cr3+), (15C5-Mn2+) and (15C5-Zn2+) complexes were obtained from the temperature dependence of the stability constants and the results show that the thermodynamics of complexation reactions is affected by nature and composition of the solvent systems and in most solution systems, the complexes are enthalpy stabilized but entropy destabilized. 相似文献