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1.
M.E. Kletskii A.A. Millov A.V. Metelitsa M.I. Knyazhansky 《Journal of photochemistry and photobiology. A, Chemistry》1997,110(3):857-270
The mechanism of light-induced transformation in the salicylideneaniline molecule was studied by semiempirical PM3 calculations. The structures and energies of the minima and saddle points (transition states) on the S0, S1 and T1 potential energy hypersurfaces (PESs) were obtained, together with the gradient lines on the PESs. The structure-energy scheme was compared with the experimental findings. According to the results obtained, the following principle processes are observed: fast S1 excited state intramolecular proton transfer (ESIPT), followed by typical ESIPT fluorescence; the formation of two S1 twisted intramolecular charge transfer (TICT) structures which quench the ESIPT fluorescence; the diabatic formation of two ground state metastable coloured “post-TICT” structures responsible for photochromism. 相似文献
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Structure and Stability of Quaternary Ammonium Interhalides: Experimental and Quantum-Chemical Study
Simonyan S. S. Kletskii M. E. Chernov'yants M. S. Gol'eva V. E. 《Russian Journal of General Chemistry》2003,73(4):575-582
The electronic structure of a series of ammonium interhalides [R1R2R3R4N]XI2, where R1 = CH3, C2H5, C3H7, F, H; R2 = R3 = R4 = CH3, H; X = Cl, Br, I, was studied by ab initio calculations (RHF/3-21G, RHF/HW, MP2/HW). The thermodynamic stability of these compounds correlates with the strength of the hydrogen bond N-H···X and three-center interhalide bond X-I-I. Calculations confirmed that, in polar solvents, these compounds preferably decompose to [R1R2R3R4N]+ and XI2
- (with subsequent decomposition of the anion), and in nonpolar solvents, to the neutral species [R1R2R3R4N]X and I2. The calculation results were compared to the experimental data obtained by single crystal X-ray diffraction, 1H NMR spectroscopy, and spectrophotometry. 相似文献
3.
V. I. Minkin A. V. Tkachuk M. E. Kletskii D. V. Steglenko V. A. Voronina S. V. Kurbatov 《Russian Chemical Bulletin》2013,62(2):464-470
Neutral aromatic electrophiles, such as trinitrobenzene and dinitrobenzofuroxane, covalently bound to the furotroponimine moiety form intramolecular through-space charge-transfer π-complexes both in solution and in the crystalline state. The kinetic and activation parameters of stereodynamic processes were determined by dynamic NMR spectroscopy. These parameters provide quantitative estimates of the kinetic stability of the p-complexes. The electronic and geometric characteristics of the π-complexes were calculated by the B3LYP/6-31G** method. 相似文献
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V. M. Krikun L. P. Sadimenko E. N. Voloshina N. A. Voloshin M. E. Kletskii 《Russian Journal of General Chemistry》2008,78(4):662-667
Spiropyrans of the indoline series were studied by differential pulse voltammetry in DMSO solutions. The experimental data obtained were supported by quantum-chemical calculations performed to examine the structural features and thermodynamic stability of a series of spiro-pyrans. The calculations revealed a correlation between the peak potential (E p) of spiropyrans and the energy of the lowest unoccupied π orbital. Procedures were developed for identification and quantitative determination of all the spiropyrans in DMSO on a mercury dropping electrode in the concentration range from 1 × 10?7 to 1 × 10?6 M. 相似文献
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Structure and Reactivity of Uracil Derivatives. 2. Ambident Nucleophilic Reactivity of 5-Diazouracil
On the basis of 3-21G type ab initio calculations we have studied all the possible complexes of 5-diazouracil with boron trifluoride. The most stable of these are the systems with the BF3 coordinated at the 3, 9, and 10 positions of the heterocyclic molecule. 相似文献
8.
O. V. Dyablo M. E. Kletskii A. F. Pozharskii E. V. Yakovleva 《Chemistry of Heterocyclic Compounds》2002,38(8):954-964
The previously unknown 1-(N-nitrosoallylamino)- and 1-(N-nitrosopropargylamino)benzimidazoles have been synthesized and they exist in solution as a mixture of the E- and Z-conformers due to hindered rotation around the N-N(O) bond. The activation energies for the EZ transition in these compounds and for the model N-benzyl analog have been determined by a dynamic 1H NMR method. With a view to studying the effect of a substituent at the amino nitrogen on the EZ isomerization we have carried out 3-21G and 6-31G** type ab initio calculations of the stable conformers of a series of N-nitrosohydrazines. 相似文献
9.
Kornienko I. V. Kletskii M. E. Vnukov V. V. Kornienko I. E. Olekhnovich L. P. 《Russian Journal of General Chemistry》2002,72(8):1243-1247
Ab initio quantum-chemical calculations were used to examine the thermodynamic aspects of binding of molecular oxygen and the radical anion O2
·- with certain amino acids. It was shown that amino acids form no stable systems with molecular oxygen but form thermodynamically stable complexes with the superoxide radical anion. 相似文献
10.
The B3LYP/6-31G** quantum chemical method was used to study the mechanism of the oxidative alkylamination of diazinones taking 1,3,6-trimethylpyrimido[4,5-d]pyrimidine-2,4,7(1H,3H,6H)-trione (lumazinone) as an example. The first limiting step of this reaction included a nucleophilic addition of alkylamine with the formation of the σH-adduct, which was oxidized by potassium permanganate in the second step. The alkylamination step proceeded in the associates formed by the lumazinone dimer and several alkylamine molecules involved in both the nucleophilic attack and the bifunctional catalysis of the process. The correlation of the Parr indices with the experimental data was studied for a number of diazinones. 相似文献