Effect of the ionic strength of a mobile phase on the chromatographic retention and thermodynamic characteristics of the adsorption of enantiomers of α-phenylcarboxylic acids on a chiral adsorbent with grafted antibiotic eremomycin
Reshetova E.N.,RAS Institute of Technical Chemistry
Russian Journal of Physical Chemistry A | Year: 2017
The effect the ionic strength of an aqueous ethanol mobile phase containing buffer salt has the on retention and thermodynamics of adsorption of optical isomers of some α-phenylcarboxylic acids on chiral adsorbent Nautilus-E with grafted antibiotic eremomycin is investigated. It is shown that ion exchange processes participate in the adsorption of enantiomers of α-phenylcarboxylic acids. It is established that electrostatic interactions contribute to the retention of enantiomers of α-phenylcarboxylic acids and affect selectivity only slightly. The dependences of retention characteristics, selectivity, and thermodynamic parameters on the concentration of the buffer salt in the eluent are determined. A statistical analysis of enthalpy–entropy compensation is performed, and the compensation effect is shown to be true. It is found that the points corresponding to the investigated adsorbates are distributed over the compensation dependence according to the spatial structural characteristics of molecules. © 2017, Pleiades Publishing, Ltd.
Asnin L.,RAS Institute of Technical Chemistry |
Kaczmarski K.,Rzeszow University of Technology |
Guiochon G.,University of Tennessee at Knoxville
Journal of Chromatography A | Year: 2010
The adsorption of the Naproxen enantiomers on the chiral stationary phase (S,S)-Whelk-O1 from methanol-water 80:20 (v/v) solutions modified with the addition of acetic acid or an acetic acid-sodium acetate buffer was studied using elution chromatography. Adsorption was found to be best accounted for by a two-site model assuming different retention mechanisms for the two enantiomers. Under experimental conditions causing a considerable degree of solute dissociation, strong distortion of overloaded band profiles is observed. This phenomenon is explained by the superimposition of the adsorption and the dissociation equilibria. The effect of the buffer composition on the retention is discussed and the results compared with previous ones obtained with the same system. The proposed model explains all the principal features of the adsorption of Naproxen on Whelk-O1 that were found earlier. Moreover this model applies well in a wider range of buffer concentrations, encompassing both the eluents in which solute dissociation is suppressed and those in which dissociation is significant. © 2010 Elsevier B.V.
Konovalova V.V.,RAS Institute of Technical Chemistry |
Maslivets A.N.,Perm State University
Russian Journal of Organic Chemistry | Year: 2013
3-Aroylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones reacted with 1,3,3-trimethyl-2-methylidene- 2,3-dihydro-1H-indole (Fischer's base) to give (2Z)-1-aryl-2-[3-oxo-3,4-dihydroquinoxalin-2(1H)-ylidene]-5-(1,3,3-trimethyl-2, 3-dihydro-1H-indol-2-ylidene)pentane-1,3,4-triones. © 2013 Pleiades Publishing, Ltd.
Lebedev A.V.,RAS Institute of Continuous Media Mechanics |
Lysenko S.N.,RAS Institute of Technical Chemistry
Journal of Magnetism and Magnetic Materials | Year: 2011
A series of samples of magnetic fluids stabilized with low-molecular weight polypropylene glycol (PPG) of different molecular masses were synthesized. The use of PPG allowed the maximum extension of the carrier fluid range to include ethyl- and butyl-acetate, ethanol, butanol, acetone, carbon tetrachloride, toluene, kerosene and PPG itself. Magnetic and rheological properties of the samples were investigated. Based on the results of investigation it has been concluded that magnetic nanoparticles are covered by a monolayer of surfactant molecules. At low temperatures the propanol-based sample preserves fluidity up to -115 °C. Measurement of critical temperatures of other base fluids showed that alcohols are the best carrier medium. Coagulation stability of the ethanol-based ferrocolloid with respect to water and kerosene was explored. It has been found that kerosene, whose fraction by weight exceeds 22.5%, does not mix with the colloid. This effect can be used to produce magneto-controllable extractors of ethyl alcohol. Under the action of water the colloid coagulates, which allows one to substitute the carrier fluid and to separate the colloid into fractions. © 2010 Elsevier B.V. All rights reserved.
Gorbunova M.,RAS Institute of Technical Chemistry |
Lemkina L.,Russian Academy of Sciences
Journal of Nanoparticle Research | Year: 2014
New water-soluble nanocomposites based on Ag and copolymers of 2,2-diallyl-1,1,3,3-tetraethylguanidiniumchloride with N-vinylpyrrolidone [poly(AGC-VP)] and vinylacetate [poly(AGC-VA)] have been developed. The average silver particle size ranged from 52 to 62 nm for poly(AGC-VA) and from 28 to 30 nm for poly(AGC-VP), with the corresponding UV-vis absorption peak position at 405-410 nm. The using of copolymers resulted in improvement in bactericide properties of composites. Following these results, the newly developed nanocomposite scaffold may be considered for new water-soluble medicines and biocides. © 2014 Springer Science+Business Media.
Grishko V.V.,RAS Institute of Technical Chemistry |
Tarasova E.V.,Russian Academy of Sciences |
Ivshina I.B.,Russian Academy of Sciences
Process Biochemistry | Year: 2013
The ability of Rhodococcus actinobacteria to transform betulin to betulone was proved and reported for the first time. Betulone, the product of regioselective oxidation of a 3β-hydroxyl group of betulin, is a useful intermediate in the synthesis of novel biologically active compounds. Of 56 strains of Rhodococcus tested, Rhodococcus rhodochrous IEGM 66 was selected because it had the highest betulin-transforming ability. It was shown that R. rhodochrous IEGM 66 growing cells transformed 0.5 g/L betulin to betulone with 45% conversion rate within 240 h. A substantial reduction in the time of betulin (0.5 g/L) biotransformation was achieved by using resting cells, which catalyzed the production of 75% betulone after 96 h. At higher initial betulin concentrations (1.0-3.0 g/L), resting cells catalyzed 40-60% betulone production within 24 h. © 2013 Elsevier Ltd. All rights reserved.
Anikina L.V.,RAS Institute of Technical Chemistry
Bioorganicheskaia khimiia | Year: 2010
The immunotropic effect of the 2,3-seco derivatives of allobetulon, betulonic acid, and the methyl ester of betulonic acid were studied. It was found that the highest activity is shown by compounds with an oleanane fragment. The presence of a free C28-carboxyl group enhances the activity of lupeolic 2,3-seco derivatives. A significant contribution to the development of the immune response is introduced by a functional group at the C3 atom in the A ring - the C3-carboxy derivatives intensify the processes of antibody production and alter the number and ratio of leukocyte forms. It is shown that 2,3-seco-1-cyano-19beta,28-epoxy-18alpha-olean-3-oic acid stimulates humoral immunity with a positive influence on hematopoiesis.
Gorbunova M.,RAS Institute of Technical Chemistry |
Anikina L.,RAS Institute of Technical Chemistry
European Journal of Medicinal Chemistry | Year: 2013
A series of polysulfones of new structural types on the basis of azanorbornenes, 2,2-diallyl-1,1,3,3-tetraethylguanidiniumchloride and tris(diethylamino)diallylaminophosphonium salts were obtained by free radical polymerization reaction. Their antioxidant properties in lipid peroxidation induced by iron/ascorbate and in erythrocyte hemolysis by H2O 2 were evaluated. The polysulfone of 2,2-diallyl-1,1,3,3- tetraethylguanidinium chloride showed protection of erythrocytes against hydrogen peroxide and thermal shock, protected epithelial cells against UV irradiation, was not toxic for erythrocytes, epithelial cells SPEV and 3T3 fibroblasts. The polysulfone of N-benzyl-2-azanorbornene-5 inhibited lipid peroxidation in liver homogenate, did not exhibit cytotoxicity in SPEV and 3T3 cells, protected these against UV irradiation. Both compounds had low bioavailability and may be recommended for further investigations as excipients to be externally applied. © 2013 Elsevier Masson SAS. All rights reserved.
Reshetova E.,RAS Institute of Technical Chemistry
Journal of Liquid Chromatography and Related Technologies | Year: 2016
The effect of the pH of aqueous-ethanol mobile phases on the retention and adsorption thermodynamics of the optical isomers of several α-phenylcarboxylic acids on a chiral stationary phase "Nautilus-E" with a grafted antibiotic, eremomycin, was studied. It was determined that ionic interactions dominated in the retention of α-phenylcarboxylic acid enantiomers. It was revealed that the Nautilus-E adsorbent was most selective to acids, the adsorption of which is an enthalpy-controlled process. It was found that the nature of adsorption was changed by varying the eluent pH. The dissociation constants of α-phenylcarboxylic acids have been determined by chromatographic method in aqueous-ethanol solution. A statistical analysis of the phenomenon of enthalpy-entropy compensation was performed, and a manifestation of the false compensation effect was established. It was shown that the spatial configuration of the molecule and the presence of polar groups on a chiral carbon atom in its structure have a greater influence on the chiral recognition mechanism of acid enantiomers using the Nautilus-E CSP. © 2016 Taylor & Francis.
Gorbunova M.N.,RAS Institute of Technical Chemistry
Russian Journal of Applied Chemistry | Year: 2011
New polymeric guanidinium and phosphonium salts derived from amino acids and polysulfones were prepared. © 2011 Pleiades Publishing, Ltd.