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41.
Abdol Reza Hajipour Morteza Karimzadeh Sirous Ghorbani Hossein Farrokhpour Alireza Najafi Chermahini 《Structural chemistry》2016,27(5):1345-1362
Electronic structures of allophanic acid were studied using MP2/6-311++G(d,p) level of theory. Five most stable tautomers were selected and stability of them was studied in detail. Obtained data showed that tautomer 1 having hydrogen atom in the central nitrogen N3 and also in a trans conformation of carbonyl and amino functional groups becomes the most stable one. Then, interconversion of these tautomers to each other was investigated step by step through internal rotation and proton transfer routes. Results indicated that movement of protons determines rate-determining step of all paths A–E. Effects of different solvents were carefully surveyed for each tautomer, and among investigated solvents, water made slight stabilization. Activation barrier for proton exchange assisted by one water molecule and one formic acid molecule was also studied, separately. Both molecules had a great influence on lowering barrier especially for proton transfer routes. Comparative MP2 study showed that the barrier will be lowered much more when acid-assisted proton exchange takes place. 相似文献
42.
Zahra Jafari Chermahini Alireza Najafi Chermahini Hossein A. Dabbagh Behzad Rezaei Neda Irannejad 《Journal of the Iranian Chemical Society》2017,14(7):1549-1556
Di(1H-tetrazol-5-yl)methane is employed as a new electron acceptor group in the synthesis of two metal-free organic dyes containing triphenylamine donor group. Dye-sensitized nanocrystalline TiO2 solar cell (DSSC) applying these novel dyes is constructed for consideration of their photovoltaic properties. The electronic properties of the dyes are also considered with the aid of theoretical calculations. The DSSC constructed from 4-(2,2-di(1H-tetrazol-5-yl)vinyl)-N,N-diphenylaniline (T1) shows a short-circuit photocurrent density of 13.38 mA cm?2, an open circuit voltage of 578 mV, and a fill factor of 0.54, with a resulted solar energy-to-electricity conversion efficiency of 4.18% under simulated 1 sun irradiation (100 mW cm?2). This result reveals that the dye with the di(1H-tetrazol-5-yl)methane anchoring group injects more electrons to the conduction band of TiO2 in comparison with its analogs with single tetrazole ring in their anchoring group. It is found that in spite of a red-shift of the absorption spectrum resulted from the lengthening of the molecule, the dye with two di(1H-tetrazol-5-yl)methane groups gives lower performance than the dye with a single electron acceptor. 相似文献
43.
In this paper, we establish exact solutions for five complex nonlinear Schrödinger equations. The semi-inverse variational principle (SVP) is used to construct exact soliton solutions of five complex nonlinear Schrödinger equations. Many new families of exact soliton solutions of five complex nonlinear Schrödinger equations are successfully obtained. 相似文献
44.
Thermal decomposition of 2,4,6-trimethylphenyl and (+)-2′-methoxy-1,1′-binaphthalen-2-yl (4-methylphenylsulfonyl)azidimidocarbonates
in the presence of norbornene, methyl acrylate, and camphene was studied. (+)-2′-Methoxy-1,1′-binaphthalen-2-yl (4-methylphenylsulfonyl)azidimidocarbonate
reacted with norbornene to give (+)-exo-2′-methoxy-1,1′-binaphthalen-2-yl N-(4-methylphenylsulfonyl)-3-azatricyclo-[3.2.1.02,4]octane-3-carboximidoate, while in the reaction with methyl acrylate a mixture of stereoisomeric methyl 1-[(2′-methoxy-1,1′-binaphthalen-2-yloxy)(4-methylphenylsulfonylimino)methyl]aziridine-2-carboxylates
was obtained. The reaction of 2,4,6-trimethylphenyl (4-methylphenylsulfonyl)azidimidocarbonate with (−)-camphene involved
insertion of intermediate nitrene into the exocyclic double bond with formation of 2,4,6-trimethylphenyl N-(3,3-dimethylbicyclo[2.2.1]heptan-2-ylidenemethyl)-N′-(4-methylphenylsulfonyl)-imidocarbamate as a 3: 1 mixture of E,E and E,Z diastereoisomers in good yield.
Published in Russian in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 10, pp. 1495–1500.
The text was submitted by the authors in English. 相似文献
45.
Mohamed Mahmoud Nasef Ezzatollah ShamsaeiPayman Ghassemi Amgad Ahmed AlyAbdul Hamid Yahaya 《Radiation Physics and Chemistry》2012,81(4):437-444
The radiation induced grafting of 4-vinylpyridine (4-VP) onto poly(ethylene-co-tetrafluoroethene) (ETFE) was optimized using the Box-Behnken factorial design available in the response surface method (RSM). The optimized grafting parameters; absorbed dose, monomer concentration, grafting time and reaction temperature were varied in four levels to quantify their effect on the grafting yield (GY). The validity of the statistical model was supported by the small deviation between the predicted (GY=61%) and experimental (GY=57%) values. The optimum conditions for enhancing GY were determined at the following values: monomer concentration of 48 vol%, absorbed dose of 64 kGy, reaction time of 4 h and temperature of 68 °C. A comparison was made between the optimization model developed for the present grafting system and that for grafting of 1-vinylimidazole (1-VIm) onto ETFE to confirm the validly and reliability of the Box-Behnken for the optimization of various radiation induced grafting reactions. Fourier transform infrared (FTIR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD) were used to investigate the properties of the obtained films and provide evidence for grafting. 相似文献
46.
47.
B. Najafi 《印度理论与应用数学杂志》2012,43(5):559-567
Using the notion of C-projectively flatness, we give a new characterization of Finsler metrics of constant flag curvature. 相似文献
48.
A novel approach using Monte Carlo method applied to simulation of low‐density polyethylene (LDPE) polymerization in tubular reactor showing topological characteristics, and the comprehensive kinetic mechanism has been taken into consideration. The results show the precise details of the structure of a chain in the three levels of the backbone, the main branches, and branches on branch. The chain types include dead polymer, dead polymer with unsaturated end, and live polymer with primary radical, secondary radical, and tertiary radical. In this work, the branches on branch were identified in terms of number, length, and position of the branch. Sixty percent of branches on branch are 1 to 5 carbons long, and the longest branch on branch is about 50 carbons. Thus, this study provides a tool for more accurately mapping the polymer chains architecture, superior to determine the number, and position of long‐ and short‐chain branches in past researches. Finally, this approach will advance the prediction of microstructure‐related properties of polymer one step further. 相似文献
49.
Adam A. Y. Oumer A. N. Najafi G. Ishak M. Firdaus M. Aklilu T. B. 《Journal of Thermal Analysis and Calorimetry》2020,139(4):2739-2768
Journal of Thermal Analysis and Calorimetry - The need for better thermal–hydraulic performance of heat exchangers remains the primary reason for further improving the design of heat... 相似文献
50.