A nice surprise for the Centers team was to see the publication in collaboration with the staff on the front cover of “Journal of Physical Chemistry B”.
S.O. Rabdano, A.V. Donets, M.A. Vovk, D.Michel, V.I. Chizhik
“ “Hydration Shells” of CH2 Groups of ω‑Amino Acids as Studied by Deuteron NMR Relaxation”
J. Phys. Chem. B, 2015, 119, 13358-13366
Hydration phenomena play a very important role in various processes, in particular in biological systems. Water molecules in aqueous solutions of organic compounds can be distributed among the following substructures: (i) hydration shells of hydrophilic functional groups of molecules, (ii) water in the environment of nonpolar moieties, and (iii) bulk water. Up to now, the values of hydration parameters suggested for the description of various solutions of organic compounds were not thoroughly analyzed in the aspect of the consideration of the total molecular composition. The temperature and concentration dependences of relaxation rates of water deuterons were studied in a wide range of concentration and temperature in aqueous (D2O) solutions of a set of ω-amino acids.
Assuming the coordination number of the CH2 group equal to 7, which was determined from quantum-chemical calculations, it was found that the rotational correlation times of water molecules near the methylene group is 1.5−2 times greater than one for pure water. The average rotational mobility of water molecules in the hydration shells of hydrophilic groups of ω-amino acids is a bit slower than that in pure solvent at temperatures higher that 60 °C, but at lower temperatures, it is 0.8−1.0 of values of correlation times for bulk water. The technique suggested provides the basis
for the characterization of different hydrophobic and hydrophilic species in the convenient terms of the rotational correlation times for the nearest water molecules.
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| Tags: Rabdano
Carlos Ernesto Avila Crisostomo (BUAP, Physics Institute “Ing. Luis Rivera Terrazas”) has presented a lecture “Magnetic properties of nanostructures based on artificial opals”
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Guest of the Center Prof. Dr. Mark Sigalov from Ben-Gurion University of the Negev (Beer Sheva, Israel) is working on the joint publication.
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D.I. Nilov, A.V. Vasilyev
“One-pot tandem hydrophenylation and ionic hydrogenation of 3-phenylpropynoic acid derivatives under superelectrophilic activation”
Tetrahedron Lett., 2015, 56, 5714-5717
The reactions of esters and amides of 3-phenylpropynoic acid with strong Lewis acids AlX3 (X = Cl, Br) or conjugate Brønsted–Lewis superacids HX-AlX3 (X = Cl, Br) in benzene and cyclohexane at room temperature afforded 3,3-diphenylpropanoic acid derivatives in up to 94% yield. This tandem reaction of the acetylene bond proceeded by hydrophenylation followed by ionic hydrogenation.
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A.N. Kazakova, R.O. Iakovenko, I.A. Boyarskaya, V.G. Nenajdenko, A.V. Vasilyev
“Acid-Promoted Reaction of Trifluoromethylated Allyl Alcohols with Arenes. Stereoselective Synthesis of CF3‑Alkenes and CF3‑Indanes”
J Org. Chem., 2015, 80, 9506-9517
Reaction of 4-aryl-1,1,1-trifluorobut-3-en-2-ols [CF3-allyl alcohols, ArCH═CHCH(OH)CF3] with arenes under activation with anhydrous FeCl3 or FSO3H was studied. We found that the transformation led to trifluoromethylated alkenes [Ar(Ar′)CHCH═CHCF3] or 1-trifluoromethylated indanes (CF3-indanes). The formation of these two types of reaction products strongly depends on the nucleophilicity of the starting arene and the electrophilicity of cationic intermediates generated from CF3-allyl alcohols under reaction conditions. Benzene, anisole, veratrole, and ortho-xylene lead exclusively to CF3-alkenes with an E-configuration. More π-donating polymethylated arenes (pseudocumene, mesitylene) afford only CF3-indanes with a predominantly cis-orientation of substituents at positions 1 and 3 of the indane ring. Meta- and para-xylenes show an intermediate behavior; they may form both CF3-alkenes and/or CF3-indanes. The mechanisms of the investigated transformations are discussed.
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Total in September 716 service applications were carried out.
All together measured:
- 1237 1H spectra
- 204 13C spectra
- 87 DEPT spectra
- 10 COSY spectra
- 17 NOESY spectra
- 70 31P spectra
- 99 19F spectra
128 applications were carried out.
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