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31.
The regio- and chemoselective polar [3+2] cycloaddition (32CA) of the Padwa carbonyl ylide (CY) with α-methylene ketone (αMK) to yield the oxa-bridged spirocycloadduct has been studied using the DFT method at the B3LYP/6-31G(d) computational level. Six reactive channels associated to the stereo-, regio-, and chemoselective approach modes of the CY to the CC and CO reactive sites of the αMK have been analyzed. DFT calculations for this cycloaddition are in complete agreement with the experimental outcome, explaining the reactivity and selectivity of the formation of the [3+2] cycloadduct. Analysis of the global and local electrophilicity and nucleophilicity indices allows an explanation about the regio- and chemoselectivity of this 32CA reaction. Intrinsic reaction coordinate (IRC) calculations and the topological analysis of the electron localization function (ELF) of the relevant points of the favored reactive channel explain the one-step two-stage nature of the mechanism of this cycloaddition. 相似文献
32.
Choosing I-concurrence as the measure of bipartite entanglement and using yon Neumann projective local measurements, localizable entanglement (LE) in a three-qutrit system is studied. A superposition of the qutrit-coherent- state of this system is considered ant its LE is obtained and analyzed as a function of the relevant parameters. It is observed that one may achieve the maximal entanglement or no entanglement at all, depending on the choice of the parameters involved. 相似文献
33.
Nawazish A. Khan M. Shamraiz S. Qamar Abbass 《Applied Physics A: Materials Science & Processing》2014,116(3):1307-1313
TlBa2(Ca3?y Be y )Cu4O12?δ (y = 0, 0.5, 1.0, 1.5, 2) samples are synthesized at normal pressure and the influence of doped Be-atoms on the superconductivity parameters at the microscopic level is investigated by carrying out excess conductivity analyses of conductivity data. The samples have shown tetragonal structure and the unit cell volume decreases with increased Be-doping. The onset temperature of superconductivity [T c(onset)] and zero resistivity critical temperature [T c(R = 0)] decrease with increased Be, however, the magnitude of diamagnetism is enhanced with Be (except for Be-doping of y = 1.0). The apical oxygen mode of the type Tl–OA–Cu(2) and CuO2 planar oxygen mode are softened as observed in FTIR absorption measurements. The FIC analyses of conductivity data have shown an increase in the coherence length along the c-axis and inter-plane coupling. The values of B c0(T), B c1(T), J c(0), τ φ are improved with the doping of Be. These observations suggested that due to the proximity effect there is less suppression in the value of the order parameter of the Cooper pairs from |ψ|2 = 1 value in the CuO2 planes in Be-doped samples that maintains the density of carriers in the conducting CuO2 planes [since the |ψ|2 = n/2] which promotes enhancement in the magnitude of superconductivity. 相似文献
34.
Fatma A. Bassyouni Sherifa M. Abu-Bakr Khaled H. Hegab Wafaa El-Eraky Ahmed A. El Beih Mohamed E. Abdel Rehim 《Research on Chemical Intermediates》2012,38(7):1527-1550
New series of 1H-perimidine-2-thiol derivatives and (2-substituted-1H-perimidin-1-yl)ethane-1,2-dione derivatives and their ligands (C24H14N4S2O2) H2L1 and (C26H18N4S2O2) H2L2 have been synthesized with transition metal ions, e.g., Copper (II), Silver (I), Cobalt (II) and Ruthenium (III) were prepared and evaluated for their antimicrobial, analgesic and anti-inflammatory activities. The synthesized compounds and their complexes were characterized by elemental analysis, 1H NMR, IR, MS, molar conductance, thermal gravimetric analysis and electronic spectra. All results revealed that compounds 3 and 13 exhibited high inhibitory effects against some bacterial strains by the disc diffusion method. On the other hand, compounds 2, 3, 7 and 12 displayed potent anti-inflammatory activity. 相似文献
35.
Issa M. El Nahhal Shehata M. Zourab Fawzi S. Kodeh Florence Babonneau Wafaa Hegazy 《Journal of Sol-Gel Science and Technology》2012,62(2):117-125
Cresol Red (CR) pH indicator was encapsulated into silica network using the sol–gel process. Transparent monolithic disks
of entrapped CR were obtained in the presence of cetyl trimethyl ammonium bromide (CTAB) or dodecyl dimethyl amino oxide (Genaminox
LA,GLA) alkyl hydroxyethyl dimethyl ammonium chloride (HY, R = 12–14) and TX-100 surfactants. UV/VIS spectra showed that the
encapsulated CR retains its structure in terms of its response to pH. At the neutral conditions it is found that the HY surfactant
is considered as proton donor as favor the cationic form of the indicator, while CTAB surfactant favor the neutral, however
GLA surfactant, the anionic form of CR is more favored because GLA has a zwitterionic head. The surfactant GLA with TEOS has
shifted the equilibrium to the ionized form of CR due to the electrostatic interaction between the surfactant and the CR anion.
Therefore their pH range is dependent on the nature of a surfactant used. It is found that the HY surfactant is more efficient
as far as loading of CR is concern and it widened the working pH range. 相似文献
36.
Wafaa S. Hamama Hamada G. El‐Gohary Mamdouh Soliman Hanfi H. Zoorob 《Journal of heterocyclic chemistry》2012,49(3):543-554
This research work describes the synthesis and biological properties of some novel isolated or fused heterocyclic ring systems with pyrazole, for example; enaminones containing pyrazolone ring photochromic functional unit, 4‐[(4‐chlorophenylamino)methylene]‐3‐methyl‐1‐phenyl‐1H‐pyrazol‐5(4H)‐one (3) and some analogous derivatives 4, 9, and 10, also as pyrazolo[3,4‐b]pyridine, pyrazolo[3,4‐b]quinoline, pyrazolo[3′,4′:4,5]thieno[2,3‐c]pyrazoline and pyrazolo[3,4‐c]pyrazole were synthesized and characterized. Newly synthesized compounds were characterized by IR, 1H NMR, 13C NMR, mass spectral data and quantum mechanical calculations. Selected products were tested for their antibacterial and antitumor agents. 相似文献
37.
Wafaa Jawaada M.S.M. Noorani M. Mossa Al-sawalha 《Nonlinear Analysis: Real World Applications》2012,13(5):2403-2413
In this paper, we demonstrate that anti-synchronization can coexist in two different hyperchaotic systems with terms of parametric uncertainty and external disturbances using the robust active sliding mode control method. By using rigorous mathematical theory, the sufficient condition is drawn for the stability of error dynamics based on the Lyapunov stability theory, where the controllers are designed by using the sum of the relevant variables in hyperchaotic systems. Numerical results are presented to justify the theoretical analysis. 相似文献
38.
Rady Shawer Mohamed Mahrous El-Shazly Adel Mohamed Khider Rowida S. Baeshen Wafaa M. Hikal Ahmed Mohamed Kordy 《Molecules (Basel, Switzerland)》2022,27(14)
The rice weevil, Sitophilus oryzae (L.), and the red flour beetle, Tribolium castaneum (Herbst), are key stored-product pests in Egypt and worldwide. The extensive use of synthetic insecticides has led to adverse effects on the environment, human health, and pest resistance. As a result, environmentally friendly pest management alternatives are desperately required. The botanical oils of jojoba, Simmondsia chinensis (L.), and rosemary, Rosmarinus officinalis L. plants growing in Egypt were extracted, identified by gas chromatography/mass spectrometry (GC–MS), and evaluated for their insecticidal activity against S. oryzae and T. castaneum. The main constituents identified in BOs were carvyl acetate (20.73%) and retinol (16.75%) for S. chinensis and camphor (15.57%), coumarin (15.19%), verbenone (14.82%), and 1,8-cineole (6.76%) for R. officinalis. The S. chinensis and R. officinalis BOs caused significant contact toxicities against S. oryzae and T. castaneum adults, providing LC50 values of 24.37, 68.47, and 11.58, 141.8 ppm at 3 days after treatment (DAT), respectively. S. chinensis oil exhibited significant fumigation toxicity against both insects; however, it was more effective against S. oryzae (LC50 = 29.52 ppm/L air) than against T. castaneum (LC50 = 113.47 ppm/L air) at 3 DAT. Although the essential oil (EO) of R. officinalis significantly showed fumigation toxicity for S. oryzae (LC50 = 256.1 and 0.028 ppm/L air at 1 and 3 DAT, respectively), it was not effective against T. castaneum. These BOs could be beneficial for establishing IPM programs for suppressing S. oryzae and T. castaneum. 相似文献
39.
Eslam M. Abbass Ali Kh. Khalil Abeer M. El-Naggar 《Journal of heterocyclic chemistry》2020,57(3):1154-1164
Herein, a rapid and highly efficient method for the synthesis of a new series of pyrimidine derivatives was demonstrated. The strategy was emanated from the reaction of hydrazinyl pyrimidine derivative ( 1 ) with different electrophilic species such as ethyl acetoacetate, ethyl 4,4,4-trifluoro acetoacetate, and phenyl isothiocyanate following cyclocondensation mechanism to afford the corresponding derivatives ( 2-6 ). Furthermore, condensation of hydrazine derivative ( 1 ) with different carbonyl compounds via conventional heating and microwave irradiation conditions was employed as a source of Schiff base derivatives bearing pyrimidine moiety ( 7-12 ). The structural features of all newly synthesized compounds were characterized by elemental and spectroscopic evidences. Some of the synthesized compounds were evaluated for in vitro cytotoxicity. The preliminary screening results showed that most of the tested compounds have moderate cytotoxic activity against HepG2 and HCT-116 cell lines. Finally, a molecular docking study was conducted to reveal the probable interaction with the thymidylate synthase enzyme. 相似文献
40.