Archive for Публикации

Carbohydrate Polymers, 2017, 169, 117–126

N.G. Voron’ko, S.R. Derkach, M.A. Vovk, P.M. Tolstoy

“Complexation of κ-carrageenan with gelatin in the aqueous phase analysed by 1H NMR kinetics and relaxation”

Carbohydrate Polymers, 2017, 169, 117–126
DOI: 10.1016/j.carbpol.2017.04.010

The 1H NMR spectroscopy is used to study the kinetics of gelation in the aqueous mixtures of κ-carrageenan with gelatin. The time dependence of NMR signals intensities shows that the kinetics of gel formation consists of classical ‘fast’ (rate constant k ≈ 6 h−1) and ‘slow’ (k ≈ 1 h−1) periods, corresponding to a coil → helix transition and subsequent aggregation of helices. Upon increase of the κ-carrageenan/gelatin (w/w) ratio Z the rate of the fast process slows down by a factor of 1.6–2.4. Further analysis was done by studying the dependence of spin-spin relaxation times of protons of gelatin on Z in the aqueous phase. A qualitative scheme describing hydrogel formation in the complex solution is given. It is hypothesized that at higher concentration of PECs the hydrogel structure network is stabilized by three types of nodes: triple helices of gelatin and intra-/inter-molecular double helices of κ-carrageenan.

Green Chemistry, 2017, 19, 3032–3041

G. Werner, K.S. Rodygin, A.A. Kostin, E.G. Gordeev, A.S. Kashin, V.P. Ananikov

“A solid acetylene reagent with enhanced reactivity: fluoride-mediated functionalization of alcohols and phenols”

Green Chemistry, 2017, 19, 3032–3041
DOI: 10.1039/C7GC00724H

source: http://pubs.rsc.org/en/Content/ArticleLanding/2017/GC/C7GC00724H#!divAbstract

The direct vinylation of an OH group in alcohols and phenols was carried out utilizing a novel CaC2/KF solid acetylene reagent in a simple K2CO3/KOH/DMSO system. The functionalization of a series of hydroxyl-group-containing substrates and the post-modification of biologically active molecules were successfully performed using standard laboratory equipment, providing straightforward access to the corresponding vinyl ethers. The overall process developed involves an atom-economical addition reaction employing only inorganic reagents, which significantly simplifies the reaction set-up and the isolation of products. A mechanistic study revealed a dual role of the F additive, which both mediates the surface etching/renewal of the calcium carbide particles and activates the C[triple bond, length as m-dash]C bond towards the addition reaction. The development of the fluoride-mediated nucleophilic addition of alcohols eliminates the need for strong bases and may substantially extend the areas of application of this attractive synthetic methodology due to increasing functional group tolerance. As a replacement for dangerous and difficult to handle high-pressure acetylene, we propose the solid reagent CaC2/KF, which is easy to handle, does not require dedicated laboratory equipment and demonstrates enhanced reactivity of the acetylenic triple bond. Theoretical calculations have shown that fluoride-mediated activation of the hydroxyl group towards nucleophilic addition significantly reduces the activation barrier and facilitates the reaction.

Science of The Total Environment 2018, 615, 1229–1238

R. Vasilevich, E. Lodygina, V. Beznosikova, E. Abakumov

“Molecular composition of raw peat and humic substances from permafrost peat soils of European Northeast Russia as climate change markers”

Science of The Total Environment 2018, 615 (In Progress, Available online 17 October 2017), 1229–1238
DOI: 10.1016/j.scitotenv.2017.10.053

source: http://www.sciencedirect.com/science/article/pii/S0048969717327560

Humic substances (HSs) from the mire peat soils of the forest-tundra zone of the European northeast part of Russia have been characterized in terms of molecular composition. This was accomplished using solid-state 13C nuclear magnetic resonance (13C NMR) techniques and electron spin resonance (ESR) spectroscopy. The composition depended on the intensity of cryogenic processes in the active layer, the quality of the humification precursors (the degree of peat material transformation), and the biochemical selection of aromatic fragments during humification. Humic acids (HAs) and fulvic acids (FAs) of the peat soils showed the presence of compounds with a low extent of condensation and a low portion of aromatic fragments, which increased with depth. A higher proportion of aliphatic carbon species was found in the HAs, indicating a low degree of organic matter stabilization. Based on the data from the two types of peat soils, we suggest that particular changes in the proportion of aromatic and unoxidized aliphatic fragments on the border of the bottom of the active layer and permafrost layers can be used as markers of current climatic change.

Journal of Molecular Structure, 2017, 1146, 554–561

A. M. Afanasenko, D. V. Boyarskaya, I. A. Boyarskaya, T. G. Chulkova, Y. M. Grigoriev, I. E. Kolesnikov, M. S. Avdontceva, T. L. Panikorovskii, A. I. Panin, A. N. Vereshchagin, M. N. Elinson

“Structures and photophysical properties of 3,4-diaryl-1H-pyrrol-2,5-diimines and 2,3-diarylmaleimides”

Journal of Molecular Structure, 2017, 1146, 554–561
DOI: 10.1016/j.molstruc.2017.06.048

source: http://www.sciencedirect.com/science/article/pii/S0022286017308293

Structural features of 3,4-diaryl-1H-pyrrol-2,5-diimines and their derivatives have been studied by molecular spectroscopy techniques, single-crystal X-ray diffraction, and DFT calculations. According to the theoretical calculations, the diimino tautomeric form of 3,4-diaryl-1H-pyrrol-2,5-diimines is more stable in solution than the imino-enamino form. We also found that the structurally related 2,3-diarylmaleimides exist in the solid state in the dimeric diketo form. 3,4-Diaryl-1H-pyrrol-2,5-diimines and 2,3-diarylmaleimides exhibit fluorescence in the blue region of the visible spectrum. The fluorescence spectra have large Stokes shifts. Aryl substituents at the 3,4-positions of 1H-pyrrol-2,5-diimine do not significantly affect fluorescence properties. The insertion of donor substituents into 2,3-diarylmaleimides leads to bathochromic shift of emission bands with hyperchromic effect.

Tetrahedron Letters, 2017, 58, 3353–3357

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
DOI: 10.1016/j.tetlet.2017.07.043

source: http://www.sciencedirect.com/science/article/pii/S0040403917308894

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.

Appl. Magn. Reson., 2017, 48(7), 731-737

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
DOI: 10.1007/s00723-017-0898-5

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.

J Therm Anal Calorim, 2017

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
DOI: 10.1007/s10973-017-6252-1

источник: https://link.springer.com/journal/10973

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.

Czech Polar Reports, 2017, 7, 1-10

E. Abakumov

“Characterisation of humic acids, isolated from selected subantarctic soils by 13C-NMR spectroscopy”

Czech Polar Reports, 2017, 7(1), 1-10
DOI: 10.5817/CPR2017-1-1

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.

Applied Catalysis: A, 2017, 542, 350-358

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
DOI: 10.1016/j.apcata.2017.06.006

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.

RSC Adv., 2017, 7, 10070-10073

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
DOI: 10.1039/c6ra26779c
источник: http://pubs.rsc.org/en/Content/ArticleLanding/2017/RA/C6RA26779C#!divAbstract

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.