«Московский государственный университет им. М.В. Ломоносова Материалы Международной конференции молодых учёных по фундаментальным наукам «ЛОМОНОСОВ - 2006» ХИМИЯ том 2 12-15 апреля 2006 года Москва ...»
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Lomonosov Moscow State University, Chemistry Department Nowadays, non-covalent modification of solid supports (e.g. cellulose) with analytical reagents is a popular approach to producing sorbents for preconcentration and determination of metal ions. Interesting variation of non-covalent modification is ‘capture’ of analytical reagent from solution during precipitation of dissolved solid matrix. This method can work if analytical reagent and solid matrix can be jointly dissolved in the same solvent. It is well known that certain imidazolium-based ionic liquids (IL;
liquid at room temperature organic salts) can dissolve cellulose. It is important that cellulose can be easily reconstituted by mere adding water. Notably, these ILs can also dissolve many analytical reagents. Herein, we report on the investigation of dissolution of cellulose in ionic liquids and successful modification of cellulose matrix with organic reagents. Dissolution of cellulose in ILs (1-butyl-3-methylimidazolium chloride, BMImCl;
1butyl-2,3,-dimethylimidazolium chloride, BM2ImCl) upon microwave and thermal heating was investigated and compared. The best solubility of cellulose was observed at thermal heating in BMImCl. Immobilization of analytical reagents via joint dissolution in IL followed by precipitation was investigated. We have found two reagents that can be effectively immobilized in that manner: 1-(2-pyridylazo)-2-naphthol (PAN) and 1-(2-thiazolylazo)-2naphthol (TAN). Films modified with PAN and TAN are stable in aqueous media in wide pH interval. Physical, physicochemical and sorption properties of obtained materials were investigated, as well as peculiar features of the films’ microscopic structure and their behavior at contact with aqueous solutions. The reagent capacity of PAN-modified film was found to be n10-3 mol/g. The optimal conditions for metal sorption from aqueous media and for metal determination were found. Modified cellulose films are suitable for quantitative determination of transition metal cations (Ni, Mn, Zn;
n10-5 M) in aqueous solutions by colorimetric technique using optical scanner. The films are easy to regenerate and reuse. We are much indebted to Prof. Yu. Zolotov who inspired this work, as well as to Profs. V. Ivanov, N. Nikonorova, I. Kubrakova, K. Bogolitsin. Thanks are also due to Russian Foundation for Basic Research for the financial support (Grant № 05-03-32976).
INCORPORATION OF SIDE – CHAIN GROUPS OF BASIC AMINO ACIDS INTO OLIGONUCLEOTIDES VIA THE 2’-POSITION OF URIDINE Kazanova E.V.
Lomonosov Moscow State University, Chemistry Department Chemically modified oligonucleotides and their conjugates represent potent tools to block gene expression within cells in culture, and are being studied as potential therapeutic agents in humans. Design of different types of oligonucleotide-based artificial ribonucleases has been attracting a significant interest, mainly because these compounds may target mRNA or viral RNA. Synthetic chemistry offers wide design opportunities for the construction of novel nucleic acid-based enzymes. Studies we present here were motivated by the need to develop a convenient method for the introduction of specific amino acid functional groups, e.g. those of histidine and lysine, into oligonucleotides. Since nucleobases in the core regions of ribozymes are often involved in various noncovalent interactions important for maintaining structure and function, the sugar part of nucleosides, particularly its 2’-position, seems to be an attractive site for ligand attachment. Our general scheme of preparation of the 2’-amino acid-functionalised uridine 3’phosphoramidites involves 2’-O-alkylation by a benzyloxycarbonylmethyl group, which can then be reduced to the corresponding 2-alkoxyethanol and attached to the -amino group of an amino acid via a carbamate linkage. After solid-phase assembly and deprotection, the resultant oligonucleotides display pendant 2’-imidazole and 2’aminoalkyl groups.
FORMULATION OF X-RAY FLUORESCENCE EXCITATION DURING STANDARDLESS ANALYSIS BY FUNDAMENTAL PARAMETER METHOD Monogarova O.V.
Lomonosov Moscow State University, Chemistry Department The theoretical calculation of element contents by fundamental parameter method (FPM) is widely used for fast and cheap standardless X-ray fluorescence (XRF) analysis of complex multicomponent subjects. The serious problem of this powerful technique – low accuracy of the determination results – is due to the absence of correct a priori information about analysed sample and working parameters of used XRF spectrometer. On this reason, in particular, for formulation of X-ray fluorescence excitation one traditionally uses universal simulated spectrum of primary radiation instead of real emission spectrum of Xray tubes that can be measured under plant conditions only . In this work the laboratory way of determination of X-ray tube emission spectrum for sequential wavelengthdispersive XRF-spectrometer was developed. This approach is based on the identity of experimentally measured XRF-spectrum and X-ray tube emission spectrum distorted during interaction of primary radiation with sample and spectrometer units. The technique includes the stages of measurement and subsequent inverse mathematical transformation of X-ray spectrum of special auxiliary sample. It is convenient for periodic accurate definition of X-ray tube emission spectrum as depreciation during exploitation. Direct mathematical formulation of X-ray fluorescence excitation by mixed (bremsstrahlung and characteristic) spectra of primary radiation needs in too complicated calculations. That is why one mathematically transforms the real polychromatic spectrum of X-ray tube into the virtual monochromatic spectrum with equivalent exciting action. There are some approaches to determination of its parameters that depend on element composition and properties of analysed sample. The least error of standardless XRF analysis results is achieved during application of virtual origin of primary X-rays with so called “equivalent analytical wavelength” . Its value does not depend on the concentration of element being determined. We developed theoretical way of this parameter definition instead of traditional empirical approach. Moreover two formulae for calculation efficient wavelength of excitation spectrum for thin-film samples were proposed in this work. The adequacy of developed ways was tested during FPM-analysis of some standard subjects. 1. V.N. Vasil’ev and et al. Spektry izlucheniya rentgenovskikh ustanovok (Radiation spectra of X-ray apparatus). Reference book. Moscow, Energoatomizdat. 1990. 143 p. 2. R. Tertian, Vie le Sage. // X-ray spectrometry. 1976. V. 5. P. 73-83.
NOVEL REAGENTS FOR HALOSULFENYLATION OF ALKENES Mukhina O.A., Gavrilova A.Y.
Lomonosov Moscow State University, Chemistry Department Halosulfenylation of alkenes is a synthetic method of great importance, which allows obtaining -halogenosulfides in a single-step reaction. Chlorosulfenylation is especially widely utilized in modern organic synthesis. Many chlorosulfenylation techniques are known. The most usual way is to utilize sulfenylchlorides as sulfenylating agents . However, such method has many drawbacks. For one, sulfenchlorides are unstable, which makes their storage impossible. Then, the proceeding of reaction requires quite harsh conditions, which makes this method unsuitable for obtaining some vulnerable compounds. Moreover, this technique is inapplicable for bromosulfenylation reactions because of nonstability of corresponding sulofenylbromides . The solution to this problem is the use of sulfenate ethers activated with phosphorus (V) oxohalides.
SAr CC X=Cl, Br + ArSOAlk POX3 CC X Reaction is characterized by simplicity of performance, high yields, ready availability of reagents. Absence of by-products and readiness of -halogenosulfides isolation are also worth mentioning. The stereochemistry of reactions confirms the electrophilic mechanism of reaction. Absence of rearrangement products suggests that reagents are of relatively low efficient electophility.
1. Krimer M. Z., Smit V. A., Shamshurin A. A., Dokl. Ak. Nauk., 1973, 208(4), 864 2. Beloglazkina E. K., Tyurin V. S., Titanyuk I. D., Zyk N. V., Zefirov N. S., Dokl. Ak. Nauk., 1995, 344(4), THE APPLICATION OF IONIC LIQUIDS IN DESULFURISATION OF OIL Nefedieva M.V., Kustov L.M.
Lomonosov Moscow State University, Chemistry Department Ionic liquids (or room-temperature molten salts), which are typically formed from an organic onium-type cation and an inorganic anion, have been known since the early 20th century. They are used as an ecologically friendly alternative to conventional organic solvents, benign catalytic media in many chemical processes, or as electrolytes has been emerged. Fast progress in this intriguing area calls for a systematic search for new types of ionic liquids, as well as for the extension of the fields of their application as potential catalysts, catalytic media, and electolytes. The possibility to specifically vary their physical and chemical properties (for example, ability to absorb S-containing compounds) make them ideal candidates for applications in desulfurisation of gasoline and diesel oil. The traditional hydrodesulfurisation can’t cope with the new restrictions of content of S-containing compounds such as thiophene, benzothiophene and dibenzothiophene. The purpose of my research work was removal of benzothiophene and dibenzothiophene from heptane and mixture of heptane and benzene (model system)with the use of ionic liquids 1-methyl-3butylimidazolium tetrafluoroborate and 1-methyl-3-octylinidazolium tetrafluoroborate and their electrochemical regeneration. Extraction of model system containing 500 ppm (part per million) of benzothiophene or dibenzothiophene with MBImBF4 and MOImBF4 has been investigated. It has been found that while increasing length of carbon chain of substitute in Imidazolium ring distribution coefficient and degree of extraction rise steeply. For increasing ring of distribution coefficient and degree of extraction cobalt complexes with various organic ligands have been added. It has been discovered that the hiest efficiency has been shown by plain complex of phthalocyanine of cobalt. For regenerating of ionic liquid after having used it for extraction electrochemical methods have been applied. For this purpose voltamperometric curves of pure ionic liquids and with addition of benzothiophene or dibenzothiophene have been obtained. Benzothiophene can be oxidized in the investigated range of potentials and dibenzothiophene can be reduced under existing conditions. The solid product of oxidation of benzothiophene from the electrode has been found to be polybenzothiophene and its structure has been proved by means of IR-spectroscopy.
MIXED PHOSPHONIUM-IODONIUM YLIDES IN REACTIONS OF NUCLEOPHILIC SUBSTITUTION Pavlova A.S., Matveeva E.D., Podrugina Т.А., Zefirov N.S.
Lomonosov Moscow State University, Chemistry Department Hypervalent iodine compounds have found a wide application in synthetic organic chemistry. It was interesting to know the reactivity of mixed phosphonium-iodonium ylides for synthesis of new classes of organic compounds. The synthesis of ylide (Iа, Ib, Ic) was carried out from corresponding phosphonium salts. We found that it is possible to perform the synthesis both by selecting intermediate ylide (III) (two-step), as well as by sequentially adding the reagents, without separation of ylide (III) (one-step) .
PhI(OCOCH3)2 HBF [Ph3P+CH2CR]ClII a, b, c a b c CH3ONa Ph3P=CHR III a, b, c Ph3P CR + BF4- I Ph I a, b, c R= COOC2H5 R= COOCH3 R= CN Ylides (Iа, Ib, Ic) were identified by IR и NMR and elemental analysis. The structure of the ylides (Ia, b) can be shown as resonance hybrid structure (I-1), (I-2), (I-3).
Ph3P Ph3P C COOR Ph3P C COOR PhI C BF4 Ia,b-3 C OR Ph I BF4 Ia,b-1 Ph I BF4 Ia,b-2 O A high barrier of rotation around the C-COOR (C-CN) bond shows the significant contribution of the type (I-3) structure. The established structure of ylide suggests its reactive ability in reactions of nucleophilic substitution. Thus, a mixed ylide (Iа) emerges as an О-nucleophile in alkylation, sililation and acilation reactions. The reaction of alkylation as the reaction of sililation occurs in two reaction centers simultaneously. In addition to reaction of ylide (Iа) as an О-nucleophile it reacts as a reagent in reaction of nucleophilic substitution of the iodonium fragment for the halide anion. 1. Matveeva E.D., Podrugina Т.А., Grishin U.K., Tkachev V.V., Zhdankin V.V., Aldoshin S.M., Zefirov N.S. Zh. Org. Chem., 2003. V. 39, P. 572.
HOMOGENEOUS HYDROXYLATION OF AROMATIC COMPOUNDS CATALYZED BY IRON(III) RESORCINARENE COMPLEXES Sakharov D.A.
Lomonosov Moscow State University, Chemistry Department Homogeneous hydroxylation of aromatic compounds by hydrogen peroxide is very important fundamental reaction. It was reported that aromatic compounds could be hydroxylated by molecular oxygen or hydrogen peroxide when iron ion and certain aromatic enediols are present in a buffered solution under neutral pH (Hamilton system) . In present work we report the design of macromolecular iron complexes of resorcinarenes which combine properties of transition metal complex with molecular recognition abilities. Resorcinarenes are the cyclic oligomers formed by condensation of resorcinol and aliphatic or aromatic aldehydes . They are suitable for formation of stable host-guest inclusion complexes with aromatic compounds. This property was used for molecular recognition of certain benzene derivatives. Macromolecular iron complexes with resorcinarenes have been sinthesized. The structure of complexes were investigated by UV spectroscopy, HPLC, MALDI-TOF, LCMS spectroscopy and NMR. It was shown that iron react with hydroxyl groups of resorcinarene which lead to quinone-like structures and «host-guest» complexes with substrates are stable. Complexes have been examined as catalysts for phenol and benzene hydroxylation by H2O2 in aqueous media. It was shown that catalyst activity and selectivity increased due to cooperative binding of substrate by the cavity of resorcinarene and Fe3+.
1. G. Hamilton, J. Friedman, P. Campbell, J. Am. Chem. Soc. 1966, 88, 5266-5268 2. D. Cram, S. Karabach, Y. Kim, L. Beczynskyj, K. Marti, R. Sampson, G. Kalleymeyn, J. Am. Chem. Soc. 1988, 110, 2554- METALLOPROTEINASE FROM KING CRAB PARALITHODES CAMTSCHATICA Semyonova S.A.
Lomonosov Moscow State University, Chemistry Department Metalloproteinase from red king crab Paralithodes camtschatica (metalloproteinase PC) has been isolated from “Moricrase” – a protease preparation obtained from king crab hepatopancreas (the digestive organ of king crab). The protease is able to cleave various protein and peptide substrates – oxidized insulin A- and B-chains, azocasein, azoalbumin. Efficiency of proteolysis depends on substrate length. Metalloprotease PC is an enzyme of broad substrate specificity: it can cleave peptide bonds formed by amino acid residues with acidic and hydrophobic side chains. The enzyme also degrades collagen – the main protein of connective tissue. Thus, it contributes to the therapeutic action of “Moricrase” which is used in medicine to treat scars, wounds and trophic ulcers. Molecular mass of the enzyme determined by electrophoresis in denaturing conditions equals 22 kDa, the isoelectric point equals 4,3. Metalloprotease PC is inhibited by metal chelators EDTA and orto-phenanthroline and activated by Co2+ and Ca2+ ions. Optimal pH for azocasein hydrolysis is 8,5, optimal temperature is 45°C. Sequence analysis showed that metalloprotease PC is closest in its structure to crayfish astacin – the prototype for a family of extracellular zinc endopeptidases. However, some structural distinctions accounting for differences in substrate specificities of the enzymes were observed. This work was supported by the Russian Foundation for Basic Research (grant No. 05-04-49087).
XRF DETERMINATION OF TRACE ELEMENTS IN WATERS AND SOLUTIONS USING PRECONCENTRATION ON FILTERS Statkus M.A., Tsysin G.I., Zolotov Yu.A.
Lomonosov Moscow State University, Chemistry Department Combined methods including preconcentration are widely used for determination of trace elements in natural waters and solutions. A promising manner is a combination of group preconcentration and multielemental determination, e. g. X-ray fluorescence (XRF). The absorption and scattering of primary and fluorescent X-ray radiation are related to the composition and surface quality of samples and contribute much to the metrological characteristics of elements determination. Thus, the choice of the most suitable technique of preconcentration for XRF analysis is required. New methods for XRF determination of As(III), Bi(III), Cd(II), Co(II), Cu(II), Fe(III), Ni(II), Pb(II), Se(IV), V(V) and Zn(II), as well as Au(III), Pd(II) and Pt(IV) in various natural, industrial samples and food-stuffs were proposed. These methods included dynamic sorption preconcentration of these elements on cellulose filters with chemically bound aminocarboxylic groups, on filters impregnated with paraffin and tri-n-octylamine. The elements were recovered on filters both as ionic forms and as hydrophobic compounds formed after mixing of the reagent and sample solution streams under dynamic conditions. The detection limits of XRF determination (“SPECTROSCAN” wavelength dispersion XRF spectrometers were used) were 0.1-0.4 µg of elements on filter. The factors influencing intensity of the fluorescent signal were a subject to theoretical and experimental investigations. It was found that maximum sensitivity of XRF determination is achieved when the elements are distributed on the filter surface but not in the bulk of the filter.
INVESTIGATION OF ASYMMETRIC EXCHANGE OF CYCLOPALLADATED LIGANDS Turubanova E.I., Razmyslova E.D., Dunina V.V.
Lomonosov Moscow State University, Chemistry Department Developing the recently discovered novel method of asymmetric C–H bond activation, based on the cyclopalladated ligand exchange (CLE), we have started studies of mechanistic aspects of this process. The main attention was focused on the system with the best previously tested homochiral cyclopalladated reagents 1a,b derived from (RC)--tertbutylbenzylamine, and prochiral tert-butyl-di-ortho-tolylphosphine (HL) as a substrate.
N C 2 (RC)-1a,b N CH N C Pd X N Pd X +P CH HL N X Pd C P CH (RC)-2a,b P CH P C Pd X P CH P Pd C (SP)-3a,b X N CH P Pd C X N CH CH (SP)-5a,b (RC,RC)-4a,b (SP,RC)-6a,b All above presented particles (proposed from general considerations) were identified in the corresponding reaction mixtures by means of P and/or 1H NMR spectroscopy re lying on the spectral parameters of previously reported complexes (3a,b), particles generated in situ (5a,b, 6a,b) or mononuclear derivatives (2a,b, 4a) prepared by an independent route. The structure of one of phosphine derivatives of type 2a was confirmed by X-ray diffraction study;
the most important result obtained at this stage was detection of a short contact (Pd…H 2.64-2.67) between the palladium atom and protons of only one of two diastereotopic Me-groups of an ortho-tolyl substituent, namely with pro(RP)-Tolo-group which is subjected to cyclopalladation in the course of CLE process. The authors thank the Russian Foundation for Basic Research (Project No. 04-0332986) for financial support of this research.
F NMR SPECTRA, STRUCTURE, AND THEORETICAL STUDY OF С70(CF3)12 AND С70(CF3) Khavrel P.A., Avdoshenko S.M.
Lomonosov Moscow State University, Chemistry Department Development of novel synthetic approaches to production of electron-withdrawing fullerene derivatives stable towards heating and hydrolysis is one of the important branches of contemporary fullerene chemistry. Among this class of substances particularly promising are trifluoromethylated fullerenes. However, large number of reaction sites being available for radical addition, fullerene trifluoromethylation generally results in complex mixtures of isomers characterized by different degrees of addition and addition patterns. Therefore, experimental structural investigations and theoretical modeling of the possible isomers are strongly required in order to elucidate the principles governing CF3 addition and, accordingly, to develop more selective synthetic methods. Herein, we present first F NMR investigations of the two C70(CF3)12 isomers and one C70(CF3)16 isomer characterized by means of single crystal X-ray diffraction in . All three compounds comprise the substructure of the single isomer of C70(CF3)10 reported in . Comparative analysis of the NMR data for C70(CF3)10, C70(CF3)12, and C70(CF3)16 have been carried out and correlation between the 6, JF-F-coupling constants and interatomic distances F-F has been investigated. Geometry optimization for all asymmetric molecules having 1,4- or 1,3-contacts between CF3-groups has been performed at the DFT level of theory with the use of the PRIRODA software , which employs computationally inexpensive implementation of the RI approach. PBE exchange-correlation functional  and an original basis set of triple zeta quality with (11s6p2d)/[6s3p2d] contraction scheme for second row atoms have been used. The experimentally obtained isomers have been shown to be the most thermodynamically stable among the whole set of structures considered.
1. S.I. Troyanov et al., Chem. Commun., 2006 (in print). 2. S. H. Strauss, O. V. Boltalina et al., Chem. Eur. J., 2006 (in print). 3. D.N. Laikov, Chem. Phys. Lett., 281, 151 (1997). 4. J.P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett., 77, 3856 (1996).
INTERCALATION AND CARBIDE FORMATION IN THE SYSTEM LITHIUM-FULLERENE C Khaskov M.A.
Lomonosov Moscow State University, Chemistry Department Lithium doped fullerides have been less studied among other alkali metals doped fullerides, perhaps, due to its lack of superconductivity. On the other hand, because of small radii of lithium, fullerenes show a considerable degree for Li atoms acceptance, yielding systems with x (LiXC60) as high as 28 . It is also known that lithium begins to react with carbon resulting in lithium carbide at approximately 720 K . So, lithium fullerides can be regarded as precursors for new carbon materials which may be possible to obtain after carbide formation. Lithium – fullerides LiXC60 with the compositions of X=1,2,3,4 and 12 were prepared by thermobaric synthesis from high purity C60 and lithium foil. For carbide formation, lithium – fullerides were treated at different temperatures (700 – 1200 K). The products obtained were characterized by XRD, DSC, IR-spectroscopy, 7Li and spectroscopy. It was shown that lithium intercalation results in reversible polymerization of C60-molecules. Heat treatment at elevated temperatures of highly doped lithium-fullerides leads to destruction of fullerene cage and formation of lithium carbides which are different from the products obtained in the system lithium – graphite.
C NMR 1. Yasukawa M., Yamanaka S. Chemical Physics Letters, 2001, V. 341, P.467-475. 2. Gurard D, Hrold A. Carbon, 1975, V.13, P.337-45.
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