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Glass Phys Chem, 2017, 43, 70–74

V.V. Tomaev, A.S. Mazur, A.S. Grevtsev

“A study of the process of thermal oxidation of lead selenide by the NMR and XRD methods”

Glass Phys. Chem., 2017, 43, 70–74
DOI:10.1134/S1087659617010163

Studies of the process of oxidation of powder samples of lead selenide in a dry air atmosphere have been performed. As shown by the methods of X-ray diffraction and scanning electron microscopy, the process of thermal treatment of samples resulted in the formation of the PbSeO3 phase, aside from the initial PbSe phase. Studies by the method of nuclear magnetic response (NMR) allowed revealing the dynamics of changes in the spectrum under the changed thermal treatment conditions.

 

Eur. J. Mineral., 2016, 28, 931–941

T.L. Panikorovskii, S.V. Krivovichev, E.V. Galuskin, V.V. Shilovskikh, A.S. Mazur, A.V. Bazai

“Si-deficient, OH-substituted, boron-bearing vesuvianite from Sakha-Yakutia, Russia: a combined single-crystal, 1H MAS-NMR and IR spectroscopic study”

Eur. J. Mineral., 2016, 28, 931–941
DOI:10.1127/ejm/2016/0028-2570

источник: http://www.ingentaconnect.com/content/schweiz/ejm/2016/00000028/00000005/art00006

Single crystals of Si-deficient vesuvianite with significant degree of hydrogarnet-type (SiO4)4−–(O4 H4)4− substitution occur as epitactic overgrowth on the surface of large wiluite crystals from the Wiluy River, Sakha–Yakutia, Russia. Electron-microprobe analysis revealed considerable Si-deficiency, Si ranging from 16.30 to 17.50 apfu. The crystal structure of the mineral has been refined in the P4/nnc space group, a = 15.5876(4), b = 11.8021(5) Å to R 1 = 0.028 for 1533 unique observed reflections. The refinement of the site-occupancy factors confirmed significant vacancy at the Z(1) and Z(2) sites (27% and 10%, respectively), with associated increase of the Z(1)–O and Z(2)–O bond lengths to 1.697 and 1.655 Å, respectively. The increased size of the Z(1) tetrahedra results in the compression of the X(1) polyhedra, while the expansion of the Z(2) tetrahedra is compensated by the compression of the X(4) polyhedra. As a result, the significant degree of the hydrogarnet-type substitutions does not have an essential influence upon the unit-cell parameters compared to the usual defect-free vesuvianite. Thermogravimetric (TGA) and differential scanning calorimetry (DSC) curves indicated two steps of the weight loss in the temperature ranges of 600–900°C (2.08 wt%) and 1014°C (2.22 wt%). The total weight loss is estimated as 4.30%, which is in good agreement with the total content of OH estimated as 13.72 apfu. The 1H solid state MAS-NMR demonstrates the presence of a strong additional line at 3.38 ppm compared to the usual vesuvianite, which is explained by the existence of the additional H(3) site. The infrared spectrum in the OH-stretching vibration region shows the additional (B′) absorption band at 3618 cm−1 typical for a hydrogarnet-type substitution.

 

Colloid Surface A, 2017, 518, 273-282

A.S. Koneva, E.A. Safonova, P.S. Kondrakhina, M.A. Vovk, A.A. Lezov, Yu.S. Chernyshev, N.A. Smirnova

“Effect of water content on structural and phase behavior ofwater-in-oil (n-decane) microemulsion system stabilized by mixednonionic surfactants SPAN 80/TWEEN 80”

Colloid Surface A, 2017, 518, 273-282
DOI:10.1016/j.colsurfa.2017.01.020
источник: http://www.sciencedirect.com/science/article/pii/S0927775717300201

For the search of effective microemulsion systems with the properties demanded for various applica-tions the knowledge of structural properties of the reverse microemulsions for various compositionsand temperatures is of high value. In the present study, the microstructure and diffusion of the compo-nents of water-in-n-decane Winsor IV microemulsions stabilized by a mixture of nonionic surfactantsSpan 80 (sorbitane monooleate, HLB 4.9) and Tween 80 (polyoxyethylene sorbitan monooleate, HLB15.0) at the weight ratios 49:51 (i.e. at the maximal ability to solubilize water) were investigatedby viscosimetry, PGSTE NMR and DLS. The system phase diagram obtained at 298.2 K includes theintermediate heterogeneous region between the reverse micelles region and the microemulsions. Thewater-to-surfactant molar ratio was changed up to 15.5 (13 wt.% of water) at the weight ratios n-decane:surfactants 65:35 and 85:15. The microemulsion droplets are spherical (that is corresponded also to thecryo-TEM data) and grow with the increase of water content. The temperature effect on the aggregatesdiffusion (and on the aggregates size) in the range 298.2–318.2 K is not pronounced. The bimodal distri-butions of the diffusion coefficients determined using both DLS and PGSTE NMR methods are specific for the system. The slower diffusion mode relates to the diffusion of mixed microemulsion droplets with theradii Rh ∼10–20 nm. The second stable form of nanoaggregates are “dry” micelles with Rh ∼ 1–2 nm. Thedata on the diffusion coefficients are of special interest in particular for the molecular dynamic simulationof the reverse micelles or of the microemulsion droplets.

 

Tetrahedron Letters, 2017, 58, 172–174

M.A. Kuznetsov, A.N. Shestakov, M. Zibinsky, M. Krasavin, C.T. Supuran, S. Kalinin, M. Tanç

“Synthesis, structure and properties of N-aminosaccharin – A selective inhibitor of human carbonic anhydrase I”

Tetrahedron Letters, 2017, 58, 172–174
DOI:10.1016/j.tetlet.2016.12.005

Previously unknown N-aminosaccharin was prepared in good yield via the one-step direct amination of saccharin sodium salt with hydroxylamine-O-mesitylenesulfonic acid (MSH) and its reactivity investigated. N-aminosaccharin and its derivatives were tested against hCA isoforms and the parent compound was identified to be a selective, low micromolar inhibitor (Ki = 8.8 lM) of hCA I. These findings provide a ligand-efficient starting point for the design of potent hCA I inhibitors – a promising drug target for retinal/cerebral edema treatment.

 

Molecules, 2016, 21, 1657-1/19

L. Sobczyk, D. Chudoba, P.M. Tolstoy, A. Filarowski

“Some Brief Notes on Theoretical and Experimental Investigations of Intramolecular Hydrogen Bonding”

Molecules, 2016, 21, 1657-1/19
DOI:10.3390/molecules21121657

A review of selected literature data related to intramolecular hydrogen bonding in ortho-hydroxyaryl Schiff bases, ortho-hydroxyaryl ketones, ortho-hydroxyaryl amides, proton sponges and ortho-hydroxyaryl Mannich bases is presented. The paper reports on the application of experimental spectroscopic measurements (IR and NMR) and quantum-mechanical calculations for investigations of the proton transfer processes, the potential energy curves, tautomeric equilibrium, aromaticity etc. Finally, the equilibrium between the intra- and inter-molecular hydrogen bonds in amides is discussed.

 

Phys. Chem. Chem. Phys., 2016, accepted

B. Koeppe, S.A. Pylaeva, C. Allolio, D. Sebastiani, E.T.J. Nibbering, G.S. Denisov, H.-H. Limbach, P.M. Tolstoy

“Polar solvent fluctuations drive proton transfer in hydrogen bonded complexes of carboxylic acid with pyridines: NMR, IR and ab initio MD study”

Phys. Chem. Chem. Phys., 2016, accepted
DOI:10.1039/C6CP06677A

koeppe

We study a series of intermolecular hydrogen-bonded 1 : 1 complexes formed by chloroacetic acid with 19 substituted pyridines and one aliphatic amine dissolved in CD2Cl2 at low temperature by 1H and 13C NMR and FTIR spectroscopy. The hydrogen bond geometries in these complexes vary from molecular (O–H…N) to zwitterionic (O…H–N+) ones, while NMR spectra show the formation of short strong hydrogen bonds in intermediate cases. Analysis of CQO stretching and asymmetric CO2 stretching bands in FTIR spectra
reveal the presence of proton tautomerism. On the basis of these data, we construct the overall proton transfer pathway. In addition to that, we also study by use of ab initio molecular dynamics the complex formed by chloroacetic acid with 2-methylpyridine, surrounded by 71 CD2Cl2 molecules, revealing a dualmaximum distribution of hydrogen bond geometries in solution. The analysis of the calculated trajectory shows that the proton jumps between molecular and zwitterionic forms are indeed driven by dipole–dipole solvent–solute interactions, but the primary cause of the jumps is the formation/breaking of weak CH…O bonds from solvent molecules to oxygen atoms of the carboxylate group.

 

J. Org. Chem., 2016, 81, 11268-11275

P. Golubev, E.A. Karpova, A.S. Pankova, M. Sorokina, M.A. Kuznetsov

“Regioselective Synthesis of 7‑(Trimethylsilylethynyl) pyrazolo [1,5‑a] pyrimidines via Reaction of Pyrazolamines with Enynones”

J. Org. Chem., 2016, 81, 11268-11275
DOI:10.1021/acs.joc.6b02217

Condensation of enynones readily available from cheap starting material with pyrazolamines provides easy access to fluorescent 7-(trimethylsilylethynyl)pyrazolo[1,5-a]pyrimidines. The reaction is straightforward, does not require the use of any additional reagents or catalysts, and can be performed without inert atmosphere. Various substituents and functional groups in both enynone and pyrazolamine are tolerated. The presented method features full regioselectivity, high isolated yields, and simplicity of both setup and product purification. Fluorescent properties of the obtained pyrazolopyrimidines were studied.

 

Beilstein J. Org. Chem., 2016, 12, 2563-2569

A.S. Pankova, P.R. Golubev, A.F. Khlebnikov, A.Yu. Ivanov, M.A. Kuznetsov

“Thiazol-4-one derivatives from the reaction of monosubstituted thioureas with maleimides: structures and factors determining the selectivity and tautomeric equilibrium in solution”

Beilstein J. Org. Chem., 2016, 12, 2563-2569
DOI:10.3762/bjoc.12.251

2-(Alkyl(aryl)amino)thiazol-4(5H)-ones can regioselectively be prepared from monoalkyl(aryl)thioureas and maleimides. In solution, the former heterocycles exist in a tautomeric equilibrium with 2-(alkyl(aryl)imino)thiazolidin-4-ones and the substituent on the exocyclic nitrogen atom governs the ratio of these tautomers. Isomers with the alkyl group in the endocyclic position can be obtained from N-methyl(ethyl)thioureas. 2D NMR spectroscopy and DFT calculations rationalize experimental results.

 

New J. Chem., 2016, 40, 10028-10040

A.V. Artem’ev, E.P. Doronina, M.I. Rakhmanova, A.O. Sutyrina, I.Yu. Bagryanskaya, P.M. Tolstoy, A.L. Gushchin, A.S. Mazur, N.K. Gusarova, B.A. Trofimov

“Luminescent CuI thiocyanate complexes based on tris(2-pyridyl)phosphine and its oxide: from mono-, di- and trinuclear species to coordination polymer”

New J. Chem., 2016, 40, 10028-10040
DOI:10.1039/C6NJ02087A

43_artemev

Tris(2-pyridyl)phosphine oxide reacts with CuSCN to form a variety of luminescent complexes, depending on the specified metal-to-ligand ratio and the solvent used, viz. mononuclear [Cu(N,N′,N′′-Py3P=O)(NCS)], dinuclear (N,N′-Py3P=O)Cu(SCN NCS)Cu[(N,N′-Py3P=O)], their co-crystal (2 : 1, correspondingly) and trinuclear {Cu(NCS)[SCNCu(N,N′,N′′-Py3P=O)]2}. In the solid state, these complexes feature red-orange emission upon UV photoexcitation. The reaction of tris(2-pyridyl)phosphine with CuSCN quantitatively produces an almost insoluble coordination polymer, [Cu(Py3P)NCS]n, which exhibits bright green emission. The synthesized compounds are the first members of the hitherto unknown family of Cu(I) thiocyanate complexes supported by tripodal ligands.

 

Tetrahedron Lett., 2016, 57, 5192-5196

M.N. Putintseva, O.Yu. Bakulina, A.Yu. Ivanov, P.S. Lobanov, S.K. Nikolskaya, I.E. Kolesnikov, D.V. Dar’in

“Double tandem cyclization of 4-(1-acyl-2,2-diaminovinyl)-6-arylpyrimidine-5-carbonitriles. Synthesis of novel peri-annulated azines”

Tetrahedron Lett., 2016, 57, 5192-5196
DOI:10.1016/j.tetlet.2016.10.020

A series of novel peri-fused azines, pyrimido[4,5,6-de]quinolino[2,3-b][1,8]naphthyridines and benzo[b]pyrimido[4,5,6-de][1,8]naphthyridines, were prepared via the base-promoted double tandem cyclization of 4-(1-acyl-2,2-diaminovinyl)-6-(haloaryl)pyrimidine-5-carbonitriles. This transformation represents a rare example of the one-pot synthesis of peri-annulated polycyclic structures from non-fused heterocycles. The synthesized pyrimido[4,5,6-de]quinolino[2,3-b][1,8]naphthyridines were found to be luminophores.