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21.
E. E. Emelina A. A. Petrov S. I. Selivanov D. V. Filyukov 《Russian Journal of Organic Chemistry》2008,44(2):251-256
Cyclocondensation of N-substituted 5-aminopyrazoles with fluorinated 1,3-diketones yielded 4-trifluoromethyl-substituted pyrazolo[3,4-b]pyridines as the only reaction products. The regiostructure of compounds obtained was proved by 1H and 13C NMR homo- and heteronuclear correlation spectroscopy. Characteristic chemical shifts in the 13C NMR spectra of regioisomeric pyrazolo[3,4-b]pyridines were established. 相似文献
22.
Secondary metabolites from Tectona philippinensis 总被引:1,自引:0,他引:1
The air-dried leaves of Tectona philippinensis, an endemic and endangered Philippine medicinal plant, afforded 5-hydroxy-3,7,4'-trimethoxyflavone (1), 5,4'-dihydroxy-3,7-dimethoxyflavone (2), squalene (3), a mixture of lupeol (4a) and beta-amyrin (4b), chlorophyllide a (5), and hydrocarbons. Antimicrobial tests on 1 and 2 indicated low antifungal activity against the fungi, Candida albicans and Trichophyton mentagrophytes. Compound 1 was also found to have low antibacterial activity against Escherichia coli and Pseudomonas aeruginosa. 相似文献
23.
I. V. Kalinovskaya T. B. Emelina A. G. Mirochnik V. E. Karasev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(8):1380-1383
The electronic absorption spectra and electronic structure of yttrium quinaldinates with an island and polymer structure were
studied. A comparative analysis of the energies of the singlet and triplet excited states, the total energies of complex compounds
in the ground state, and Mulliken’s bond overlap populations was performed by the TD-DFT method with the B3LYP density functional.
For yttrium quinaldinate with a polymer structure, the distance between the highest occupied and lowest unoccupied orbitals
was found to be longer than for the compound with an island structure. The transition energies were shifted to the blue region,
which accounts for the higher stability of the polymer compound. 相似文献
24.
Irina Fomina Zhanna Dobrokhotova Grygory Aleksandrov Anna Emelina Mikhail Bykov Irina Malkerova Artem Bogomyakov Lada Puntus Vladimir Novotortsev Igor Eremenko 《Journal of solid state chemistry》2012
The new 1D coordination polymer {Tm(Piv)3}n (1), where Piv=OOCBut?, was synthesized in high yield (>95%) by the reaction of thulium acetate with pivalic acid in air at 100 °С. According to the X-ray diffraction data, the metal atoms in compound 1 are in an octahedral ligand environment unusual for lanthanides. The magnetic and luminescence properties of polymer 1, it’s the solid-phase thermal decomposition in air and under argon, and the thermal behavior in the temperature range of ?50…+50 °С were investigated. The vaporization process of complex 1 was studied by the Knudsen effusion method combined with mass-spectrometric analysis of the gas-phase composition in the temperature range of 570–680 K. 相似文献
25.
T. B. Emelina I. V. Kalinovskaya A. G. Mirochnik 《Russian Journal of General Chemistry》2016,86(9):2088-2094
The analysis of electron structure of yttrium(III) complexes with cinnamic and quinaldic acids was carried out. Electron transitions were assigned, and influence of the nature of frontier orbitals on the position of absorption bands in the electron spectra was revealed. The TD-DFT calculation has shown that different ratios of intensities of π–π* and n–π* bands in the electron absorption spectra of the compounds are caused by different natures of frontier orbitals of the complexes. It was found that dipole moments of both complexes increase upon photoexcitation, greater changes being observed in Y(III) quinaldate. The reason of the greater Stokes shift of Y(III) quinaldate was established. 相似文献
26.
A regioselective synthesis was carried out of 7-trifluoromethylpyrazolo[1,5-a]pyrimidines by reaction of 3(5)aminopyrazoles with 1,3-diketones containing CF3 group. The characteristic chemical shifts were established for C5 and C7 atoms of the pyrimidine ring and of substituents thereof in the 1H, 13C, and 19F NMR spectra of pyrazolo[1,5-a]pyrimidines. 相似文献
27.
A. L. Emelina Zh. V. Dobrokhotova A. A. Sinelshchikova Yu. A. Velikodnyi I. G. Fomina P. S. Koroteev V. M. Novotortsev I. L. Eremenko 《Russian Journal of Inorganic Chemistry》2010,55(11):1754-1761
Kinetic analysis of the thermolysis of samarium pivalate [Sm2(μ2-OOCCMe3)4(OOCCMe3)2(HOOCCMe3)6] · HOOCCMe3 (1) was carried out (the input data were differential scanning calorimetry (DSC) and thermogravimetry data), and a mathematic
model of the process was developed that allowed us to optimize (by calculation) the conditions for formation of {Sm(OOCCMe3)3}
n
(2) samarium tris-pivalate via thermal decomposition of complex 1. The results of the thermal study of samarium and gadolinium tris-pivalates in the temperature range of −50…+50°C are reported.
Specific anomalies were found in the DSC curves and heat capacity versus temperature curves in the temperature range of 0–50°C. 相似文献
28.
E. V. Fedorenko B. V. Bukvetskii A. G. Mirochnik T. B. Emelina V. E. Karasev 《Russian Chemical Bulletin》2009,58(11):2240-2245
The structures and spectral luminescence properties of two similar in structure β-diketonatoboron difluorides were studied
in comparison. One of them (1-(2,4,6-trimethyl-phenyl)butane-1,3-dionatoboron difluoride (1)) contains two methyl groups in the both ortho-positions of the phenyl ring, which excludes the formation of rotamers with the planar configuration. In the second compound,
1-phenylbutane-1,3-dionatoboron difluoride (2), the α-phenyl substituent can rotate freely. The steric factor exerts no effect on monomer fluorescence but substantially
affects the ability of benzoylacetonatoboron difluorides to undergo intermolecular interactions, which leads to considerable
differences in the luminescence properties of concentrated solutions and crystals of compounds 1 and 2. 相似文献
29.
Polishchuk AV Karaseva ET Emelina TB Cramariuc O Karasev VE 《Journal of fluorescence》2011,21(6):2117-2122
Electronic absorption, luminescence, IR and Raman spectra of polymorphous forms of fluoroquinolones were investigated. Assignment
of the band maxima due to π→π* and n→π* electronic transitions were done. The structural changes are responsible for the absorption
band modifications. One-electron transitions in the long wavelength region, excitation wavelengths, oscillator strengths and
involved molecular orbitals for the zwitter-ionic and cationic protonated forms for different fluoroquinolones were calculated
with quantum-chemical and molecular dynamic methods. The electron density redistributions on the FQs separate fragments during
the photoexcitation to the S1*-state were carry out by Mulliken calculations. It was shown that the degree of neutral and zwitter-ion FQs penetration through
the bacterium membrane is different. 相似文献
30.
A. I. Rusanov N. E. Esipova A. I. Emelina 《Russian Journal of General Chemistry》2007,77(12):2108-2112
Contact angles formed by water with the surface of the K-8 optical glass and the cover glass for microscopy under the condition of stress were studied. At bending glass plates, the contact angle is always larger on the convex (stretched) side than on the concave (compressed) side. Thus, the mechanochemical effect of the strain sign at wetting of glass is observed. 相似文献