N 10 N-(2-Carboxyethyl)chitosans: Regioselective synthesis, characterisation and protolytic equilibria [Text] / Yu. A. Skorik, C. A. R. Gomes, M. T.S.D. Vasconcelos, Yu. G. Yatluk // Carbohydrate Research. - 2003. - Vol. 338, № 3. - P271-276 Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): CARBOXYETHYLATION POLYSACCHARIDES -- N-(2-CARBOXYETHYL)CHITOSAN -- POLYAMPHOLYTE Аннотация: N-(2-Carboxyethyl)chitosans were obtained by reaction of low molecular weight chitosan with a low degree of acetylation and 3-halopropionic acids under mild alkaline media (pH 8-9, NaHCO3) at 60°C. The chemical structure of the derivatives obtained was determined by 1H and 13C NMR spectroscopies. It was found that alkylation of chitosan by 3-halopropionic acids proceeds exclusively at the amino groups. The products obtained are described in terms of their degrees of carboxyethylation and ratio of mono-, di-substitution and free amine content. The protonation constants of amino and carboxylate groups of a series of N-(2-carboxyethyl)chitosans were determined by pH-titration at ionic strength 0.1 M KNO3 and 25°C. © 2002 Elsevier Science Ltd. All rights reserved. |
C 74 Complexation models of N-(2-carboxyethyl)chitosans with copper(II) ions [Text] / Yu. A. Skorik, C. A. R. Gomes, N. V. Podberezskaya, G. V. Romanenko, L. F. Pinto, Yu. G. Yatluk // Biomacromolecules. - 2005. - Vol. 6, № 1. - P189-195 . - ISSN 1525-7797 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: The copper(II) complex formation equilibria of N-(2-carboxyethyl)chitosans with three different degrees of substitution (DS = 0.42, 0.92, and 1.61) were studied in aqueous solution by pH-potentiometric and UV-spectrophotometric techniques. It was demonstrated that the complexation model of CE-chitosans depends on DS: the [Cu(Glc-NR2)2] complexes are predominant for two lower substituted samples ("bridge model", log ?12 = 10.06 and 11.6, respectively), whereas the increase of DS leads to formation mainly of the [Cu(Glc-NR2)] complexes ("pendant model", log ?11 = 6.41). As a model for copper complexation with a disubstituted residue of CE-chitosan, the complex of N-methyliminodipropionate [CuMidp(H2O)]·(H2O) was synthesized and structurally characterized by XRD. The unit cell consists of two crystallographically nonequivalent Cu atoms having slightly distorted square pyramidal coordination; Midp constitutes the basal plane of the pyramid and acts as a tetradentate NO3 chelate-bridging ligand by the formation of two six-membered chelate rings (average Cu-O 1.99 A, Cu-N 2.04 A) and a bridge via carbonyl O atom (average Cu-O 1.99 A), an apical position is occupied by a water molecule (average Cu-Ow 2.30 A). |
B 62 Bis[N-(2-hydroxyethyl)-beta-alaninato]-copper(II) [Text] / A. V. Pestov, E. V. Peresypkina, A. V. Virovets, N. V. Podberezskaya, Yu. G. Yatluk, Yu. A. Skorik // Acta Crystallographica Section C: Crystal Structure Communications. - 2005. - Vol. 61, № 12. - Pm510-m512 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: The CuII ion in the title complex, [Cu(C5H 10NO3)2] or [Cu(He-ala)2] [He-ala = W-(2-hydroxyethyl)-?-alaninate], resides at the inversion centre of a square bipyramid comprised of two facially arranged tridentate He-ala ligands. Each He-ala ligand binds to a CuII ion by forming one six-membered ?-alaninate chelate ring in a twist conformation and one five-membered ethanolamine ring in an envelope conformation, with Cu-N = 2.017 (2) A, Cu-OCoo = 1.968 (1) A and Cu-OOH = 2.473 (2) A. The [Cu(He-ala)2] molecules are involved in a network of O-H?O and N-H?O hydrogen bonds, forming layers parallel to the (101?) plane. The layers are connected into a three-dimensional structure by van der Waals interactions, so that the molecular centres form pseudo-face-centered close packing. © 2005 International Union of Crystallography???? |
N 10 N-alkylation of chitosan by beta-halopropionic acids in the presence of various acceptors [Text] / A. V. Pestov, Yu. A. Skorik, G. Kogan, Yu. G. Yatluk // Journal of Applied Polymer Science . - 2008. - Vol. 108, № 1. - P119-127 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: N-carboxyethylation of chitosan by -halopropionic acids in the presence of various proton and halogen ion acceptors was investigated. It has been observed that carboxyethylation of chitosan in aqueous medium is accompanied by the by-processes of hydrolysis and dehydrohalogenation of the -halopropionic acids yielding -hydroxypropionic acid, bis(2-carbox-yethyl) ether, and acrylic acid. Degree of carboxyethyl substitution (DS) of chitosan and the relative rates of the by-processes varied significantly depending on the conditions used and nature of the proton or halogen ion acceptor. At carboxyethylation of chitosan with the alkaline -bromopropionates, the DS increased in the order Cs+ Rb- K+ sim; Na+ Li-. |
I-60 Influence of metal coordination on conductivity behavior in poly(butadiene-acrylonitrile)-CoCl2 system [Text] / O. V. Bushkova, I. P. Koryakova, Yu. A. Skorik, B.I. Lirova, A. V. Pestov, V. M. Zhukovskii // Electrochimica Acta. - 2008. - Vol. 53, № 16. - P5322-5333 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: The metal complex formation and the electrical properties of amorphous solid polymer electrolytes, based on poly(butadiene-acrylonitrile) copolymer (PBAN) and CoCl2, have been studied over the homogeneity region of the system limited by the CoCl2 concentration of 1.89 mol kg-1. It has been found that ionic conductivity is carried out by the unipolar anion transfer at lower CoCl2 concentrations (up to 0.10 mol kg-1). As the CoCl2 concentration increases, electronic conductivity appears in addition to ionic conductivity, and the former becomes dominant, starting from 0.38 mol kg-1. It has been shown that the nature of charge carriers is determined by the composition of metal complexes formed by CoCl2 and the macromolecular solvent PBAN. At lower concentrations, the [Co2L2Cl4]0 dimers are the predominant species (L being macromolecule side groups C{triple bond, long}N), and their dissociation is followed by the formation of mobile Cl- anions and immobile binuclear [Co2Cl3]+ complexes. As CoCl2 concentration increases, polynuclear [ConL2Cl2n]0 (n 2) complexes appear (L being C{triple bond, long}N and C{double bond, long}C groups of PBAN). Specific features of chemical bonds in ?-complexes of transition metals result in the appearance of electronic charge carriers. The abrupt increase in conductivity observed at the highest CoCl2 concentration is connected with the formation of a percolation network of polynuclear [ConL2Cl2n]0 complexes |
A 62 Antioxidant and antimutagenic activity of N-(2-carboxyethyl)chitosan [Text] / G. Kogan, Yu. A. Skorik, I. Zitnanova, L. Krizkova, Z. Durackova, C. A. R. Gomes, Yu. G. Yatluk, J. Krajcovic // Toxicology and Applied Pharmacology . - 2004. - Vol. 201, № 3. - P303-310 : ил. - Библиогр.: с. 309-310 (49 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): CARBOXYETHYLATION -- CHITOSAN -- EUGLENA GRACILIS -- OFLOXACIN -- ANTIOXIDANT -- ANTIMUTAGENICITY Аннотация: The antioxidant and antimutagenic activities of the novel carboxyethyl derivatives of chitosan with three different degrees of substitution have been assayed in vitro in the unicellular flagellate Euglena gracilis subjected to the action of genotoxic agents acridine orange and ofloxacin. It has been demonstrated that chitosan derivatives exhibit concentration-dependent protective antigenotoxic activity against both mutagens. It is suggested that different mechanisms may be involved in its protective action—antioxidant activity in case of ofloxacin-induced DNA damage, as well as possible interaction with the cell membrane that prevents acridine orange from reaching the genetic compartments and subsequent damaging DNA through intercalative binding. Direct adsorption of acridine orange on chitosan derivatives was ruled out as a possible mechanism of protection on the basis of spectrophotometric measurements. Dependence of the antimutagenic properties of the studied chitosan derivatives on the degree of substitution was reversed in experiments involving acridine orange and ofloxacin, which also indicated different mechanisms of protection involved in these two cases.???? |
P 49 Pestov, A. V. In-gel carboxyethylation of chitosan by beta-halopropionic acids [] : доклад, тезисы доклада / A. V. Pestov, Yu. A. Skorik, Yu. G. Yatluk // 10-th International Conference on Chitin and Chitosan - 7th International Conference of the European Chitin Society, Le Corum, Montpellier, France, 6-9 September 2006 : book of abstracts . - Le Corum, Montpellier (France), 2006. - 76 (PC 11) Рубрики: ХИМИЧЕСКИЕ НАУКИ |
P 49 Pestov, A. V. Triocarbaamoylation of chitosan [] : доклад, тезисы доклада / A. V. Pestov, Yu. A. Skorik, Yu. G. Yatluk // 10-th International Conference on Chitin and Chitosan - 7th International Conference of the European Chitin Society, Le Corum, Montpellier, France, 6-9 September 2006 : book of abstracts . - Le Corum, Montpellier (France), 2006. - 76 (PC 12) Рубрики: ХИМИЧЕСКИЕ НАУКИ |
Y 32 Yatluk, Yu. G. Novel unique reagent for preparation of carboxyethyl chitosan-beta-acryloyloxyproprionic acids [] : доклад, тезисы доклада / Yu. G. Yatluk, A. V. Pestov, Yu. A. Skorik // 10-th International Conference on Chitin and Chitosan - 7th International Conference of the European Chitin Society, Le Corum, Montpellier, France, 6-9 September 2006 : book of abstracts . - Le Corum, Montpellier (France), 2006. - 77 (PC 13) Рубрики: ХИМИЧЕСКИЕ НАУКИ |
S 73 Sorption properties of the modified chitin-glucans [] : доклад, тезисы доклада / M. A. Yurovskikh, A. V. Pestov, G. Kogan, Yu. A. Skorik, Yu. G. Yatluk // Proceedings of the 7th Asia-Pacific Chitin and Chitosan Symposium "Advances in chitin science and technology", Bexco, Busan, Korea, 23-26 April 2006. - Handrimwon, 2006. - С. 60-62. - Библиогр.: с. 61 (2 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ |
P 49 Pestov, A. V. In-gel synthesis of N-(2-carboxyethyl)chitosan [] : доклад, тезисы доклада / A. V. Pestov, Yu. G. Yatluk, Yu. A. Skorik // Proceedings of the 7th Asia-Pacific Chitin and Chitosan Symposium "Advances in chitin science and technology", Bexco, Busan, Korea, 23-26 April 2006. - Handrimwon, 2006. - С. 90-91. - Библиогр.: с. 91 (9 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ |
N 52 New hybrid chelating sorbents with grafted 3-aminopropionate groups based on mixed silicon, aluminum, titanium, or zirconium oxides [Electronic resource] / Yu. G. Yatluk, N. A. Zhuravlev, O. V. Koryakova, L. K. Neudachina, Yu. A. Skorik // Russian Chemical Bulletin (Translation of Izvestiya Akademii Nauk, Seriya Khimicheskaya). - 2005. - Vol. 54, № 8. - P1836-1841 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: A series of new hybrid organo-inorganic sorbents with the 3-aminopropionate chelating group was synthesized. The synthesis includes the copolycondensation (sol—gel method) of tetraethoxysilane, 3-aminopropyltriethoxysilane, and several modifiers (MeSi(OEt)3, EtSi(OEt)3, Ti(OEt)4, AlONO3, ZrOCl2) followed by carboxyethylation with acrylic acid. The obtained chelating sorbents were characterized by elemental analysis, FT-IR and 1H NMR spectroscopy, and thermogravimetry. The N-carboxylated sorbents have a higher sorption capacity with respect to metal ions (0.5–0.9 mmol g?1, pH 6.3, NH4OAc, 20 °C) than the starting sorbents with the primary amino group (0.05–0.2 mmol g?1) and manifest high selectivity for copper(II) ion extraction \\\\Expert2\\nbo\\Russian Chemical Bulletin\\2005, 54 (8), 1836.pdf |
S 98 Synthesis and sorption properties of new hybrid chelating sorbents with ?-alanine functional groups [Electronic resource] / Yu. G. Yatluk, D. V. Eremin, L. K. Neudachina, Yu. A. Skorik // Russian Chemical Bulletin (Translation of Izvestiya Akademii Nauk, Seriya Khimicheskaya). - 2004. - Vol. 53, № 12. - P2730-2735 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: A series of gamma-aminopropylsilylated sorbents was obtained from different oxide supports (silica gels, silica fillers, macroporous glasses, alumina) and by the direct synthesis (hydrolytic polycondensation of tetraalkoxysilanes with gamma-aminopropyltriethoxysilane). The highest degree of immobilization was achieved for silicas, while the most convenient solvent was methanol. Sorbents with beta-alanine functional groups were obtained by the subsequent reaction with acrylic acid. The degree of beta-carboxyethylation was 1.3–1.9, and the highest content of functional groups (vCOOH = 3.23 mmol g–1) was achieved for carboxyethylated xero gel synthesized by the copolycondensation of tetraethoxysilane with -aminopropyltriethoxysilane. The sorbents containing beta-alanine possess a higher selectivity of Cu2+ ion sorption than the initial gamma-aminopropylsilylated sorbents \\\\Expert2\\nbo\\Russian Chemical Bulletin\\2004, 53 (12), 2730.pdf |
P 93 Protolytic Equilibria of Some N,N-Bis(2-carboxyethyl)aminoazobenzenesulfonic Acids in Aqueous Solution [Electronic resource] / Yu. A. Skorik, L. K. Neudachina, A. V. Osintsev, Yu. G. Yatluk, A. A. Vshivkov, E. V. Osintseva // Russian Journal of Organic Chemistry (Translation of Zhurnal Organicheskoi Khimii). - 2002. - Vol. 38, № 3. - P385-389 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: 4-[4-Bis(2-carboxyethyl)aminophenylazo]benzenesulfonic acid and 4-[2-bis(2-carboxyethyl)amino-4,5-dimethylphenylazo]benzenesulfonic acid were synthesized for the first time by azo coupling of diazosulfanilic acid with N,N-bis(2-carboxyethyl)aniline and N,N-bis(2-carboxyethyl)-3,4-xylidine, respectively. The acid ionization constants of the products were determined, their electron absorption spectra were measured, and schemes of acid-base equilibria in aqueous solution were proposed \\\\Expert2\\nbo\\Russian Journal of Organic Chemistry\\2002, 38 (3), 385.pdf |
3,3,3-Trifluoro-N-(3-trifluoromethylphenyl)-1,2-propanediamine and its N-mono-and N,N-dicarboxyethyl derivatives: synthesis, protolytic and complexation properties [Electronic resource] / V. Yu. Korotaev, Yu. A. Skorik, A. Yu. Barkov, M. I. Kodess, A. Ya. Zapevalov // Russian Chemical Bulletin (Translation of Izvestiya Akademii Nauk, Seriya Khimicheskaya). - 2005. - Vol. 54, № 11. - P2545-2549 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: 3,3,3-Trifluoro-N-(3-trifluoromethylphenyl)-1,2-propanediamine (5) was synthesized by the reaction of 2-diazo-1,1,1-trifluoro-3-nitropropane or 3,3,3-trifluoro-1-nitropropene with 3-aminobenzotrifluoride followed by the reduction of the nitro group. The Michael 1,4-addition of diamine 5 to acrylic acid occurs only at the N(1) atom and affords N-mono-or N,N-dicarboxyethyl derivatives 6 and 7, depending on the reactant ratio. Protolytic equilibria 5–7 in aqueous solutions were studied by pH-potentiometry and UV spectroscopy. Only the aliphatic amino group can be protonated in an aqueous solution, while the aromatic amino group remains unprotonated even in 12 M HCl. The stability constants of transition metal (Cu2+, Ni2+, Zn2+) complexes with ligands 5–7 were determined by pH-potentiometric titration. The stability of the complexes and selectivity of the ligands toward Cu2+ ions increase with an increase in the number of N-carboxyethyl groups \\\\Expert2\\nbo\\Russian Chemical Bulletin\\2005, 54 (11), 2545.pdf |
S 66 Skorik, Yu. A. Evaluation of various chitin-glucan derivatives from Aspergillus niger as transition metal adsorbents [Text] / Yu. A. Skorik, A. V. Pestov, Yu. G. Yatluk // Bioresource Technology . - 2010. - Vol. 101, № 6. - P1769-1775 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: A number of chelating resins were prepared by chemical derivatization of the chitin-glucan (CG) complex isolated from Aspergillus niger biomass, namely chitosan-glucan (CsG), O-carboxymethyl-chitin-glucan (CM-CG), O-(2-sulfoethyl)chitin-glucan (SE-CG), and N-(2-carboxyethyl)chitosan-glucan (CE-CsG). The chemical modification was confirmed by FT-IR and elemental analysis. Nanosecond electron beam irradiation was used to produce insoluble resins and to preserve the reactive functional groups. Batch experiments were carried out to evaluate the adsorption selectivity and capacity of the resins toward transition metal ions (Cu2+, Ni2+, Co2+, Zn2+). The resins showed good adsorption capability with the following selectivity series: Co2+ Ni2+ Cu2+ Zn2+. The total metal adsorption capacities of CG, CsG, CM-CG, SE-CG, and CE-CsG resins at pH 6.5 (ammonium acetate buffer) were found to be 0.205, 0.382, 1.752, 0.319, and 0.350 mmol g?1, respectively. Our results suggest that, depending on the type of chemical modification, the chitin-glucan complexes can be used either for selective Cu2+ removal (CsG) or for total transition metal adsorption (CM-CG) from aqueous effluents |
I-57 In-gel carboxyethylation of chitosan and the molecular architecture of the products [Text] / A. V. Pestov, G. Kogan, Yu. A. Skorik, Yu. G. Yatluk, M. Pajtinka // 1st European chemistry Congress. - Budapest, Hungary, 2006. - Vol. 2. - P295. - Bibliogr. : p. 295 (2 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ |
S 98 Synthesis, characterization and some properties of N-(2-carboxyethyl)chitosan [Text] / Yu. A. Skorik, C. A. R. Gomes, M. T.S.D. Vasconcelos, Yu. G. Yatluk // Advances in Chitin Science : Proceedings of the 5th Asia Pacific Chitin and Chitosan Symposium & Exhibition, Bangkok, Thailand, March 13-15, 2002. - Bangkoki, 2002. - Vol. 5. - P344+348 : il. - Bibliogr. : p. 348 (19 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): CHITOSAN -- CARBOXYETHYL -- ALKYLATION -- POLYAMPHOLYTE -- POTENTIOMETRIC TITRATION -- PROTONATION CONSTANTS |
Y 32 Yatluk, Yu. G. Hybrid silica-based chelating sorbents with beta-alanine functional groups [Text] / Yu. G. Yatluk, Yu. A. Skorik // International conference "From molecules towards materials" : IV Razuvaev lectures, Russia, Nizhny Novgorod, Septemper 3-11, 2005. - Nizhny Novgorod, 2005. - P125 : il. - Bibliogr. : p. 125 (2 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): CHELATING SORBENTS -- SILICA-BASED MATERIALS -- OXIDE -- HYDROLISIS |
C 21 Carboxyalkylation of chitosan in the gel state / Yu. A. Skorik, A. V. Pestov, M. I. Kodess, Yu. G. Yatluk // Carbohydrate Polymers. - 2012. - Vol. 90, № 2. - С. 1176-1181 Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): CHITOSAN -- CHEMICAL MODIFICATION -- GEL TECHNIQUE Аннотация: This study presents a new approach for direct carboxyalkylation of chitosan in the gel state by using aza-Michael addition and substitution reactions. Various reagents were applied including acrylic and crotonic acids, and alpha-, beta-, gamma-, delta-, and epsilon-halocarboxylic acids. The reaction of chitosan with gamma- and delta-halocarboxylic acids showed no target product formation either in solution or in the gel state. In the case of acrylic, crotonic, alpha- and beta-halocarboxylic acids, the reaction performed in the gel state (concentration of chitosan 20-40%) shows higher degree of substitution at lower reaction time and temperature than in diluted solutions (concentration of chitosan 0.5-2%). The results were discussed in terms of kinetics of the target and side reactions. H-1 and C-13 NMR confirmed that in all cases the carboxyalkylation of chitosan proceeds exclusively at the amino groups \\\\Expert2\\nbo\\Carbohydrate Polymers\\2012, v. 90, p.1176.pdf |