S. Miltsov, V. Karavan, A. Misharev, G. Starova, J. Alonso-Chamarro, M. Puyol
“Unprecedented acid-catalyzed Wurtz-type coupling of meso-bromoindodicarbocyanine dyes”
Tetrahedron Letters, 2017,58, 3353–3357
meso-Bromosubstituted indodicarbocyanine dyes produce dimeric molecules, together with the debrominated species, under acid catalysis. The relationship between the dimerization and hydrodebromination routes depends on the aryl substitution of the dyes. A possible reaction mechanism is also proposed.
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A photo-session of the working process was held in the CMR.
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D.S. Mazing, A.V. Nikiforova, A.S. Osinin, V.A. Moshnikov, Yu.V. Bogachev, S.M. Sukharzhevskii
“Electron Paramagnetic Resonance Investigations of ZnSe:Mn Nanocrystals”
Appl. Magn. Reson., 2017, 48(7), 731-737
Colloidal nanocrystals of ZnSe doped with Mn2+ were synthesized in non-polar medium using hot-injection technique. Obtained samples were characterized by means of photoluminescence and absorption spectroscopies. To confirm the incorporation of Mn2+ impurity and to reveal its state and localization, electron paramagnetic resonance (EPR) spectroscopy was employed. As a result, EPR spectra were analyzed and hyperfine splitting constant and g-factor for Mn2+ dopant were determined.
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| Tags: Sukharzhevskii
M. Brusnikina, O. Silyukov, M. Chislov, T. Volkova, A. Proshin, A. Mazur, P. Tolstoy, I. Terekhova
“Effect of cyclodextrin complexation on solubility of novel anti-Alzheimer 1,2,4-thiadiazole derivative”
J Therm Anal Calorim, 2017
New 1,2,4-thiadiazole derivative displaying neuroprotective potential and high activity in the treatment of Alzheimer’s disease has been synthesized. The objective of this study was to improve the aqueous solubility of this drug-like compound by means of complex formation with native and hydroxypropylated β-cyclodextrins. To this end, aqueous solubility of 1,2,4-thiadiazole derivative was investigated in the presence of β-cyclodextrins. It was shown that the phase solubility diagrams are of Bs type demonstrating the initial increase in thiadiazole solubility in solutions of cyclodextrins (concentration up to 0.01 mol kg−1) followed by a solubility decrease due to the precipitation of the complexes formed. In comparison with β-cyclodextrin, hydroxypropyl-β-cyclodextrin displays more pronounced solubilizing action since it forms more stable complexes with thiadiazole. Solid complexes of 1,2,4-thiadiazole derivative with β-cyclodextrins were prepared by grinding and freeze-drying methods. DSC, TG, hot-stage microscopy, solid-state 13C MAS CP/TOSS NMR, powder X-ray diffractometry and FTIR spectroscopy were used to prove the existence of complexes in the solid state. Solubility of the obtained formulations was also examined. It was found that complexes of thiadiazole with hydroxypropyl-β-cyclodextrin exhibited higher solubility in phosphate buffer (pH 7.4) compared with pure thiadiazole and its complexes with β-cyclodextrin.
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| Tags: Mazur
“Characterisation of humic acids, isolated from selected subantarctic soils by 13C-NMR spectroscopy”
Czech Polar Reports, 2017, 7(1), 1-10
Soils of Antarctic considered as underestimated in terms of soils organic matter polls, organic remnants humification/mineralization rates and biogenic-abiogenic interactions. Humic acids of selected Sub Antarctic soils were investigated in terms of elemental and structural composition with special reference to evaluation of organic matter stabilisation degree and assessment of carbon species distributions in the molecules with use of solid state 13C-NMR spectroscopy. It was shown, that the prevailing of aliphatic compounds on the aromatic one is more pronounced in Antarctic soils than in Arctic ones. Average portion of the aromatic compounds is about 20% in humic acids, extracted from soils with evident ornitogenic effect from Fildes Peninsula (Norh-West Antarctic peninsula). This indicates that the role of humification precursors composition is the leading in the humification process. The stabilisation rate of the Antarctic HAs can be assessed as low and the potential risk of biodegradation of their molecules are high.
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P.Mäki-Arvela, J.Zhu, N.Kumar, K. Eränen, A.Aho, J.Linden, J.Salonen, M.Peurla, A.Mazur, V.Matveev, D.Y.Murzin
“Solvent-free “green” amidation of stearic acid for synthesis of biologically active alkylamides over iron supported heterogeneous catalysts”
Applied Catalysis: A, 2017, 542, 350-358
Stearoyl ethanolamine was synthesized by amidation of stearic acid with ethanolamine in solventless conditions. Iron containing heterogeneous catalysts supported on SiO2, Al2O3, Beta (BEA), ZSM-12 (MTW) and Ferrierite (FER) were used in this work. Sn-modified Ferrierite and H-Ferrierite were also studied for comparison. Fe-modified catalysts synthesized using solid state ion-exchange and evaporation impregnation methods, were thoroughly characterized with X-ray powder diffraction, scanning electron microscope, FTIR with pyridine, nitrogen adsorption, energy dispersive X-ray microanalysis and Mössbauer spectroscopy. The highest conversion was obtained with Fe-H-FER-20 at 140 °C in 1 h giving 61% conversion and 98% selectivity towards the desired amide. The catalytic performance in terms of turnover frequency per mole of iron was achieved with the catalyst exhibiting the largest amount of Fe3+ species, optimum acidity and a relatively low Brønsted to Lewis acid site ratio.
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| Tags: Mazur
A.S. Smirnov, D.N. Nikolaev, V.V. Gurzhiy, S.N. Smirnov, V.S. Suslonov, A.V. Garabadzhiu, P.B. Davidovich
“Conformational stabilization of isatin Schiff bases – biologically active chemical probes”
RSC Adv., 2017, 7, 10070-10073
Isatin Schiff base derivatives have a wide range of biological effects. Unfortunately, these compounds possess a serious topological shortcoming: the conformational E ⇆ Z interconversion. Two ways of conformation stabilization are reported here: complexation with metals that stabilize the E-conformer and substitution in the 4th position of the isatin core stabilizing the Z-form.
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| Tags: Smirnov
A. Stukalov, V.V. Sokolov, V.V. Suslonov, M.A. Kuznetsov
“Pyrazoles and C-Imidoylaziridines through [4+1] Annulation and [2+1] Cycloaddition of 1-Azabuta-1,3-dienes with a Synthetic Equivalent of Phthalimidonitrene”
Eur. J. Org. Chem., 2017, 2587-2595
Oxidative addition of N-aminophthalimide to 1,2,4-triaryl-1-azabuta-1,3-dienes leads, in most cases, to the regiodefined formation of 1,3,5-triarylpyrazoles in moderate to good yields through [4+1] annulation. This transformation is supposed to proceed by nitrenoid attack onto a lone pair of electrons of the imine nitrogen atom to give the vinylazomethine imine, followed by its 1,5-electrocyclization into pyrazoline and further aromatization into pyrazole. Rare examples of 2-imidoyl-1-phthalimidoaziridines that are formed by competitive [2+1] cycloaddition onto the C=C bond were isolated in low yields for 1-azadienes with electron-deficient aryl substituents at the imine nitrogen atom.
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One can find review of CMR in our brochure
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Mikhail Vovk has presented an excursion-lecture about modern NMR spectroscopy methods for high school students. The equipments presented in CMR and some aspect of its application were demonstrated during the excursion.
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| Tags: Vovk