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Sample records for hydrocarbon-nucleic acid complexes

  1. Photoinduced electron transfer and fluorescence mechanisms in covalently linked polynuclear aromatic-nucleotide complexes

    Energy Technology Data Exchange (ETDEWEB)

    Geacintov, N.E.; Mao, Bing; Zhao, Rushen; Chen, Junxin; Liu, Tong Ming; Ya, Nai-Qi [New York Univ., NY (United States). Dept. of Chemistry; France, L.L.; Sutherland, J.D. [Brookhaven National Lab., Upton, NY (United States)

    1992-04-01

    The fluorescence of polycyclic aromatic hydrocarbon-nucleic acid complexes is quenched by photoinduced electron transfer mechanisms in aqueous solutions at ambient temperatures. These effects are illustrated with the biologically important compound benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE), a mutagenic and carcinogenic metabolite of the environmental pollutant benzo[a]pyrene, which forms covalent mutagenic lesions with 2{prime}-deoxyguanosine (dG) residues in DNA. The dependence of the fluroescence yeild and fluorescence decay times of the covalent model adduct (+)-trans-BPDE-N{sup 2}-dG as a function of temperature and methanol/water composition are described. Because of the sensitivity of the fluorescence of the pyrenyl residue to the polarity of the microenvironment, the magnitude of the fluorescence yield can be used to distinguish between highly hydrophobic (e.g. intercalation) and other more solvent-exposed BPDE-nucleic acid binding sites.

  2. Photoinduced electron transfer and fluorescence mechanisms in covalently linked polynuclear aromatic-nucleotide complexes

    Energy Technology Data Exchange (ETDEWEB)

    Geacintov, N.E.; Mao, Bing; Zhao, Rushen; Chen, Junxin; Liu, Tong Ming; Ya, Nai-Qi (New York Univ., NY (United States). Dept. of Chemistry); France, L.L.; Sutherland, J.D. (Brookhaven National Lab., Upton, NY (United States))

    1992-01-01

    The fluorescence of polycyclic aromatic hydrocarbon-nucleic acid complexes is quenched by photoinduced electron transfer mechanisms in aqueous solutions at ambient temperatures. These effects are illustrated with the biologically important compound benzo(a)pyrene-7,8-diol-9,10-epoxide (BPDE), a mutagenic and carcinogenic metabolite of the environmental pollutant benzo(a)pyrene, which forms covalent mutagenic lesions with 2{prime}-deoxyguanosine (dG) residues in DNA. The dependence of the fluroescence yeild and fluorescence decay times of the covalent model adduct (+)-trans-BPDE-N{sup 2}-dG as a function of temperature and methanol/water composition are described. Because of the sensitivity of the fluorescence of the pyrenyl residue to the polarity of the microenvironment, the magnitude of the fluorescence yield can be used to distinguish between highly hydrophobic (e.g. intercalation) and other more solvent-exposed BPDE-nucleic acid binding sites.

  3. -Heterocyclic Carbene Complexes of Mineral Acids

    KAUST Repository

    Brill, Marcel

    2016-11-08

    We have synthesized and characterized new gold-N-heterocyclic carbene (NHC) complexes derived from the deprotonation of mineral acids. The use of sulfuric acid was a particularly interesting case. These complexes were tested in known gold-catalyzed reactions, such as the hydration of alkynes and the Meyer–Schuster rearrangement. They proved to be highly efficient in both reactions.

  4. Complex coacervates of hyaluronic acid and lysozyme

    DEFF Research Database (Denmark)

    Water, Jorrit J.; Schack, Malthe M.; Velazquez-Campoy, Adrian;

    2014-01-01

    Complex coacervates of hyaluronic acid and lysozyme, a model protein, were formed by ionic interaction using bulk mixing and were characterized in terms of binding stoichiometry and protein structure and stability. The complexes were formed at pH 7.2 at low ionic strength (6 mM) and the binding s...

  5. Physical Studies of Some Hydrazinobenzoic Acid Complexes

    Institute of Scientific and Technical Information of China (English)

    M.G.Abd El Wahed; S.Abd El Wanees; M. El Gamel; S.Abd El Haleem

    2005-01-01

    The stability constants of complexes of 2-hydrazinobenzoic acid and 4-hydrazinobenzoic acid with Ni (Ⅱ), Cu (Ⅱ),Zn (Ⅱ), Cd (Ⅱ), and Hg (Ⅱ) were determined potentiometrically at different temperatures. The thermodynamic parameters,△AG°,△AH°, and △S° were calculated and proved that the complexation process is spontaneous and endothermic. The thermodynamic functions were analyzed in terms of electrostatic and non-electrostatic components and the results reveal that ionic bonds are formed between the studied ligands and metal ions. Conductometric titration was shown that the stoichiometry of the formed complexes are M:L and M:2L. The structure of the prepared solid complexes was characterized using IR, 1H NMR, 13C NMR spectroscopies as well as X-ray diffraction technique.Finally electrical conductivity of the ligands and their copper complexes was measured and shown that the ligands have a semiconductor behaviour.

  6. Complex coacervates of hyaluronic acid and lysozyme

    DEFF Research Database (Denmark)

    Water, Jorrit J.; Schack, Malthe M.; Velazquez-Campoy, Adrian

    2014-01-01

    by differential scanning calorimetry. Furthermore, the protein stability of lysozyme was found to be improved upon complexation during a 12-weeks storage study at room temperature, as shown by a significant increase in recovered protein when complexed (94 ± 2% and 102 ± 5% depending on the polymer-protein weight...... stoichiometry was determined using solution depletion and isothermal titration calorimetry. The binding stoichiometry of lysozyme to hyaluronic acid (870 kDa) determined by solution depletion was found to be 225.9 ± 6.6 mol, or 0.1 bound lysozyme molecules per hyaluronic acid monomer. This corresponded well...... with that obtained by isothermal titration calorimetry of 0.09 bound lysozyme molecules per hyaluronic acid monomer. The complexation did not alter the secondary structure of lysozyme measured by Fourier-transform infrared spectroscopy overlap analysis and had no significant impact on the Tm of lysozyme determined...

  7. Complexation and molecular modeling studies of europium(III)-gallic acid-amino acid complexes.

    Science.gov (United States)

    Taha, Mohamed; Khan, Imran; Coutinho, João A P

    2016-04-01

    With many metal-based drugs extensively used today in the treatment of cancer, attention has focused on the development of new coordination compounds with antitumor activity with europium(III) complexes recently introduced as novel anticancer drugs. The aim of this work is to design new Eu(III) complexes with gallic acid, an antioxida'nt phenolic compound. Gallic acid was chosen because it shows anticancer activity without harming health cells. As antioxidant, it helps to protect human cells against oxidative damage that implicated in DNA damage, cancer, and accelerated cell aging. In this work, the formation of binary and ternary complexes of Eu(III) with gallic acid, primary ligand, and amino acids alanine, leucine, isoleucine, and tryptophan was studied by glass electrode potentiometry in aqueous solution containing 0.1M NaNO3 at (298.2 ± 0.1) K. Their overall stability constants were evaluated and the concentration distributions of the complex species in solution were calculated. The protonation constants of gallic acid and amino acids were also determined at our experimental conditions and compared with those predicted by using conductor-like screening model for realistic solvation (COSMO-RS) model. The geometries of Eu(III)-gallic acid complexes were characterized by the density functional theory (DFT). The spectroscopic UV-visible and photoluminescence measurements are carried out to confirm the formation of Eu(III)-gallic acid complexes in aqueous solutions.

  8. Complex Pharmacology of Free Fatty Acid Receptors

    DEFF Research Database (Denmark)

    Milligan, Graeme; Shimpukade, Bharat; Ulven, Trond

    2017-01-01

    G protein-coupled receptors (GPCRs) are historically the most successful family of drug targets. In recent times it has become clear that the pharmacology of these receptors is far more complex than previously imagined. Understanding of the pharmacological regulation of GPCRs now extends beyond...... pharmacology have shaped understanding of the complex pharmacology of receptors that recognize and are activated by nonesterified or "free" fatty acids (FFAs). The FFA family of receptors is a recently deorphanized set of GPCRs, the members of which are now receiving substantial interest as novel targets...... for the treatment of metabolic and inflammatory diseases. Further understanding of the complex pharmacology of these receptors will be critical to unlocking their ultimate therapeutic potential....

  9. Crystal structure of putrescine aspartic acid complex

    OpenAIRE

    Ramaswamy, S.; Murthy, MRN

    1990-01-01

    Polyamines, putrescine, spermidine and spermine are ubiquitous biogenic cations believed to be important for a variety of cellular processes. In order to obtain structural information on the interaction of these amines with other biomolecules, the structure of a complex of putrescine with aspartic acid was determined using single crystal X-ray diffraction methods. The crystals belong monoclinic space group $C_2$ with $a = 21.504 \\AA$, $b = 4.779 \\AA$, $c = 8.350 \\AA$ and $\\beta = {97.63}^{\\ci...

  10. 21 CFR 172.315 - Nicotinamide-ascorbic acid complex.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Nicotinamide-ascorbic acid complex. 172.315 Section... HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.315 Nicotinamide-ascorbic acid complex. Nicotinamide-ascorbic acid complex may be safely used in accordance with the following prescribed...

  11. Behavior of carboxylic acids upon complexation with beryllium compounds.

    Science.gov (United States)

    Mykolayivna-Lemishko, Kateryna; Montero-Campillo, M Merced; Mó, Otilia; Yáñez, Manuel

    2014-07-31

    A significant acidity enhancement and changes on aromaticity were previously observed in squaric acid and its derivatives when beryllium bonds are present in those systems. In order to know if these changes on the chemical properties could be considered a general behavior of carboxylic acids upon complexation with beryllium compounds, complexes between a set of representative carboxylic acids RCOOH (formic acid, acetic acid, propanoic acid, benzoic acid, and oxalic acid) and beryllium compounds BeX2 (X = H, F, Cl) were studied by means of density functional theory calculations. Complexes that contain a dihydrogen bond or a OH···X interaction are the most stable in comparison with other possible BeX2 complexation patterns in which no other weak interactions are involved apart from the beryllium bond. Formic, acetic, propanoic, benzoic, and oxalic acid complexes with BeX2 are much stronger acids than their related free forms. The analysis of the topology of the electron density helps to clarify the reasons behind this acidity enhancement. Importantly, when the halogen atom is replaced by hydrogen in the beryllium compound, the dihydrogen bond complex spontaneously generates a new neutral complex [RCOO:BeH] in which a hydrogen molecule is lost. This seems to be a trend for carboxylic acids on complexing BeX2 compounds.

  12. Ni(II) complexes of dithiophosphonic acids

    Indian Academy of Sciences (India)

    Afshin Saadat; Alireza Banaee; Patrick McArdle; Karim Zare; Khodayar Gholivand; Ali Asghar Ebrahimi Valmoozi

    2014-07-01

    The reaction of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson reagent) with isobutanol, cyclohexylamine and phenylethylamine produced (4-methoxy-phenyl)-phosphonodithioic acid o-isobutyl ester HS2P(p-C6H4OMe) (OCH2CH(CH3)2) (I), [S2P(C6H11NH)(p-C6H4OMe) H3N+C6H11] (II) and [S2P(phCH2CH2NH) (p-C6H4OMe)H3N+CH2CH2ph] (III), respectively. The reaction of alcohol with Lawesson reagent produced neutral product (I) while that with amines led to an ion pair (II, III). Furthermore, reaction of I, II and III with NiCl2.6H2O in methanol produced novel complexes: IV, V and VI. The compounds were characterized by 1H, 13C and 31P NMR, IR spectroscopy and elemental analysis. The single crystal X-ray structures of IV and V showed that the nickel complexes are square planar. Compound V formed a three-dimensional supramolecular structure via intermolecular P-O…H-N hydrogen bonds. The Xray crystallography of V showed that those three hydrogens of +NH3 cation produced three hydrogen bonds with different distances. The new compounds were additionally tested in view of their anti-bacterial properties. The ligands containing amine substituents exhibited more activity toward tested bacteria than their alcohol substituents, while the Ni(II) complexes including alcohol substituents exhibited high potential.

  13. STABILITY OF BINARY COMPLEXES OF L-ASPARTIC ACID IN ...

    African Journals Online (AJOL)

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    KEY WORDS: Binary complexes, Stability constants, Aspartic acid, ... It is miscible with water, oils, and most organic solvents, ... coordinated to the metal ion. ..... Figure 3. Structures of Asp complexes where S is either solvent or water molecule.

  14. Chemodynamics of soft nanoparticulate complexes: Cu(II) and Ni(II) complexes with fulvic acids and aquatic humic acids

    NARCIS (Netherlands)

    Town, R.M.; Leeuwen, van H.P.; Buffle, J.

    2012-01-01

    The dynamics of metal complexation by small humic substances (fulvic acid and aquatic humic acid, collectively denoted as "fulvic-like substance", FS) are explored within the framework of concepts recently developed for soft nanoparticulate complexants. From a comprehensive collection of published e

  15. Boron complexing with H-resorcinol and acidic hydroxyxanthene dyes

    Energy Technology Data Exchange (ETDEWEB)

    Nazarenko, V.A.; Flyantikova, G.V.; Chekirda, T.N. (AN Ukrainskoj SSR, Odessa. Fiziko-Khimicheskij Inst.)

    1984-01-01

    Complex formation of boron with H-resorcinol (hr; 2,4-dihydroxybenzene-azo -8-hydroxynaphtalene-3,6-disulfonic acid) and acidic hydroxyxanthene dyes (hxd: fluorescein, eosine, erathrosine). Mixed-ligand complexes with a ratio of r:hr:hxd=1:1:1 are formed at pH=5-6. The chemism of the complex formation of boron with H-resorcinol and fluorescein has been studied. The stability constant of the complex is 1.12x10/sup 21/, the conditional molar absorptivitis 1.80x10/sup 0/. This complex formation reaction was used for photometric determination of boron in natural water.

  16. Copper (II) diamino acid complexes: Quantum chemical computations regarding diastereomeric effects on the energy of complexation

    NARCIS (Netherlands)

    Zuilhof, H.; Morokuma, K.

    2003-01-01

    Quantum chemical calculations were used to rationalize the observed enantiodifferentiation in the complexation of alpha-amino acids to chiral Cu(II) complexes. Apart from Cu(II)-pi interactions and steric repulsions between the anchoring cholesteryl-Glu moiety and an aromatic amino acid R group, hyd

  17. Antibacterial Activity of Copper and Cobalt Amino Acids Complexes

    Directory of Open Access Journals (Sweden)

    ANDREEA STĂNILĂ

    2011-11-01

    Full Text Available The antibacterial properties of differently copper and cobalt amino acids complexes on agar plates was investigated in the present study. The antibacterial activity of amino acid complexes was evaluated against on three bacteria strains (Escherichia coli, Bacillus cereus, Micrococcus luteus. Generally, the amino acids complexes were mainly active against gram-positive organisms, species like Micrococcus luteus being the most susceptible strain tested. It was registered a moderate antibacterial activity against Bacillus cereus. The microorganisms Escherichia coli, which are already known to be multi-resistant to drugs, were also resistant to the amino acids complexes but also to the free salts tested. Escherichia coli were susceptible only to the CoCl2 and copper complex with phenylalanine. The complexes with leucine and histidine seem to be more active than the parent free ligand against one or more bacterial species. Moderate activity was registered in the case of complexes with methionine and phenylalanine. From the complexes tested less efficient antibacterial activity was noted in the case of complexes with lysine and valine. These results show that cobalt and copper complexes have an antibacterial activity and suggest their potential application as antibacterial agents.

  18. Complex pharmacology of free fatty acid receptors

    OpenAIRE

    Milligan, Graeme; Shimpukade, Bharat; Ulven, Trond; Hudson, Brian D.

    2017-01-01

    G protein-coupled receptors (GPCRs) are historically the most successful family of drug targets. In recent times it has become clear that the pharmacology of these receptors is far more complex than previously imagined. Understanding of the pharmacological regulation of GPCRs now extends beyond simple competitive agonism or antagonism by ligands interacting with the orthosteric binding site of the receptor to incorporate concepts of allosteric agonism, allosteric modulation, signaling bias, c...

  19. Investigation of interpolymer complexes based on methylcellulose and polyacrylic acid

    Directory of Open Access Journals (Sweden)

    Zh. Nurpeysova

    2012-12-01

    Full Text Available In the given work the patterns of formation interpolymer complexes in the methylcellulose and polyacrylic acid system were studied by turbidimetry. It is shown that the increase in molecular weight and concentration of polymers promotes efficient formation of interpolymer complexes.

  20. Complex formation of p-carboxybenzeneboronic acid with fructose

    Energy Technology Data Exchange (ETDEWEB)

    Bulbul Islam, T.M.; Yoshino, K. [Shinshu Univ., Department of Chemistry, Matsumoto, Nagano (Japan)

    2000-10-01

    To increase the solubility of p-caboxybenzeneboronic acid (PCBA) in physiological pH 7.4, the complex formation of PCBA with fructose has been studied by {sup 11}B-NMR. PCBA formed complex with fructose and the complex increased the solubility of PCBA. The complex formation constant (log K) was obtained in pH 7.4 as 2.75 from the {sup 11}B-NMR spectra. Based on this result the complex formation ability of PCBA with fructose has been discussed. (author)

  1. Technetium(I) Complexes of Bathophenanthrolinedisulfonic Acid.

    Science.gov (United States)

    Yazdani, Abdolreza; Janzen, Nancy; Czorny, Shannon; Valliant, John F

    2017-03-06

    Bathophenanthrolinedisulfonate (BPS) complexes of technetium(I) of the type [Tc(CO)3(BPS)(L)](n) (L = imidazole derivatives) were synthesized and evaluated both in vitro and in vivo. [(99m)Tc(CO)3(BPS)(MeIm)](-) (MeIm = 1-methyl-1H-imidazole) was prepared in near-quantitative yield using a convenient two-step, one-pot labeling procedure. A targeted analogue capable of binding regions of calcium turnover associated with bone metabolism was also prepared. Here, a bisphosphonate was linked to the metal through an imidazole ligand to give [(99m)Tc(CO)3(BPS)(ImAln)](2-) (ImAln = an imidazole-alendronate ligand) in high yield. The technetium(I) complexes were stable in vitro, and in biodistribution studies, [(99m)Tc(CO)3(BPS)(ImAln)](2-) exhibited rapid clearance from nontarget tissues and significant accumulation in the shoulder (7.9 ± 0.2% ID/g) and knees (15.1 ± 0.9% ID/g) by 6 h, with the residence time in the skeleton reaching 24 h. A rhenium analogue, which is luminescent and has the same structure, was also prepared and used for fluorescence labeling of cells in vitro. The data reported demonstrate the potential of this class of compounds for use in creating isostructural optical and nuclear probes.

  2. Phase Chemistry of the Complexes of RE Amino Acids

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Forty-three phase diagrams of ternary system concerning rare earth salts, α-amino acids and water, which were constructed by phase equilibrium methods, were expounded. The influences of the factors such as cations, anions, the structure of amino acids, temperature on the phase diagrams were discussed. Under the guidance of phase equilibrium results, over 150 new solid complexes were prepared. IR, reflecting, UV, FS, and Raman spectra for these complexes were investigated and the regularity of “tripartite effect”, “tetrad effect”, “Nephelanxetic effect”, “Oddo-Harkins” was observed. Thermal decomposition processes of the complexes were confirmed. Based on the comparison with the known crystal structures of rare earth-amino acid-complexes, an estimation method for predicting the crystal structure data of series complexes was founded. The constant volume combustion energies of the complexes were determined by RBC-1 type rotating bomb calorimeter. The standard enthalpies of combustion and standard enthalpies of formation were calculated for these complexes.

  3. Study on Copolymerization of Rare Earth-Carboxylic Acid Complex

    Institute of Scientific and Technical Information of China (English)

    Qiu Guanmin(邱关明); Zhang Ming(张明); Yan Chang hao(严长浩); Zhou Lanxiang(周兰香); Dai Shaojun(戴少俊); Okamo to Hiroshi

    2003-01-01

    Complex of rare earth with carboxylic acid was prepared by precipita tion and direct method. It was copolymerized with such monomers as acrylic acid and other ones to synthesize ionomer of rare earth and organic polymer with different rare earth contents. Its glass-transition temperature and heat stability were analyzed by TG and DTA. Infra-red detector was used to show its structure. The effect of rare earth complex prepared by different methods on copolymerization and properties of copolymers was also discussed.

  4. Complexes with Mercaptosuccinic Acid and Hydrazine as Ligands

    Directory of Open Access Journals (Sweden)

    S. Devipriya

    2013-01-01

    Full Text Available Reaction of hydrazine and mercaptosuccinic acid with metal ions forms\tcomplexes with general formula [Ln(N2H42CH2(COOCH(SH(COO1.5]·(H2O, where Ln = La(III, Pr(III, Nd(III, Sm(III, and Gd(III at pH 5. The complexes have been characterized by elemental analysis, IR and UV-visible spectroscopic, thermal and X-ray diffraction studies. The IR data reveal that the acid moiety in the complexes is present as dianion due to the deprotonation of COOH groups by lanthanides in these complexes, leaving –SH group unionized and hydrazine as bidental neutral ligand showing absorptions in the range of 945–948 cm−1. The thermoanalytical data evince that the complexes are stable up to 103°C and undergo complete decomposition in the range of 550–594°C resulting in metal oxides. SEM images of La2O3 and Gd2O3 residues show their nano sized clusters suggesting that the complexes may be used as precursors for nano La2O3 and Gd2O3, respectively. X-ray powder diffraction patterns show isomorphism among the complexes. The kinetic parameters of the decomposition of the complexes have been computed by Coats-Redfern equation.

  5. Equilibrium and release properties of hyaluronic acid-drug complexes.

    Science.gov (United States)

    Battistini, Franco David; Olivera, María Eugenia; Manzo, Rubén Hilario

    2013-07-16

    With the aim to provide more rational basis about the potentiality of hyaluronic acid (or hyaluronan) as drug carrier a set of ionic complexes of its acid form (HA) and its sodium salt (NaHA) with three model drugs (D) (atenolol, propranolol and lidocaine) were prepared. Besides NaHA subjected to hyalurodinase depolimerization (NaHA(d)) was also used. Transparent dispersions were obtained. They exhibited negative electrokinetic potential and a high degree of counterionic condensation with affinity constants (log Kcc) in the range of 5.8-6.1 for propranolol complexes (pK(a) 9.45) and 4.0-4.6 for lidocaine ones (pK(a) 7.92). Delivery rates of D from the complexes were measured in a Franz-type bicompartimental device. Loaded D were slowly released from the three types of complexes, even when a neutral salt was added to the dispersion placed in the donor compartment, revealing the high affinity between the protonated drugs and the ionisable groups of the polymer. Complex dispersions based on HA or on NaHA(d) exhibited lower viscosity than those of NaHA but their complexing ability remained unaltered. The results reported on equilibrium and release properties of Hyaluronan-model D complexes contribute to expand the use of HA and NaHA as drug carriers for different routes of administration.

  6. Physico-chemical studies of some aminobenzoic acid hydrazide complexes

    Directory of Open Access Journals (Sweden)

    S. ABD EL HALEEM

    2004-04-01

    Full Text Available The stability constants and related thermodynamic functions characterizing the formation of divalent Ni, Cu, Zn, Cd and Hg complexes with o- and p-aminobenzoic acid hydrazide were determined potentiometrically at different temperatures. The formations of the complexes are endothermic processes. The formed bonds are mainly electrostatic. Conductometric titration was carried out to determine the stoichiometry and stability of the formed complexes. The structures of complexes were characterized by their IR, 1H-NMR and 13C-NMR spectra, as well as X-ray diffractograms. The coordination process takes place through the carbonyl group and the terminal hydrazinic amino group. The thermal stability of the complexes was followed in the temperature range 20–600ºC.

  7. Nucleic Acid-Peptide Complex Phase Controlled by DNA Hybridization

    Science.gov (United States)

    Vieregg, Jeffrey; Lueckheide, Michael; Leon, Lorraine; Marciel, Amanda; Tirrell, Matthew

    When polyanions and polycations are mixed, counterion release drives formation of polymer-rich complexes that can either be solid (precipitates) or liquid (coacervates) depending on the properties of the polyelectrolytes. These complexes are important in many fields, from encapsulation of industrial polymers to membrane-free segregation of biomolecules such as nucleic acids and proteins. Condensation of long double-stranded DNA has been studied for several decades, but comparatively little attention has been paid to the polyelectrolyte behavior of oligonucleotides. We report here studies of DNA oligonucleotides (10 - 88 nt) complexed with polylysine (10 - 100 aa). Unexpectedly, we find that the phase of the resulting complexes is controlled by the hybridization state of the nucleic acid, with double-stranded DNA forming precipitates and single-stranded DNA forming coacervates. Stability increases with polyelectrolyte length and decreases with solution salt concentration, with complexes of the longer double-stranded polymers undergoing precipitate/coacervate/soluble transitions as ionic strength is increased. Mixing coacervates formed by complementary single-stranded oligonucleotides results in precipitate formation, raising the possibility of stimulus-responsive material design.

  8. Catalytic Hydrogenation over Palladium Complex of Molecular Complex of Poly(4-vinylpyridine) with Acetic Acid

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The palladium complex of the molecular complex of poly(4-vinylpyridine) with acetic acid(PVP/HAc-Pd) was prepared. Its catalytic activity for the hydrogenation of nitrobenzene was found much higher than that of the corresponding palladium complex of poly(4-vinylpyridine). In the presence of a strong inorganic alkali, especially potassium hydroxide, the catalytic activity is greatly improved. The suitable hydrogenation condition for PVP/HAc-Pd is to use 0.1 mol/L ethanol solution of potassium hydroxide as the hydrogenation medium and the hydrogenation is carried out at 45 ℃.

  9. Quantification of acidic compounds in complex biomass-derived streams

    Energy Technology Data Exchange (ETDEWEB)

    Karp, Eric M.; Nimlos, Claire T.; Deutch, Steve; Salvachúa, Davinia; Cywar, Robin M.; Beckham, Gregg T.

    2016-01-01

    Biomass-derived streams that contain acidic compounds from the degradation of lignin and polysaccharides (e.g. black liquor, pyrolysis oil, pyrolytic lignin, etc.) are chemically complex solutions prone to instability and degradation during analysis, making quantification of compounds within them challenging. Here we present a robust analytical method to quantify acidic compounds in complex biomass-derived mixtures using ion exchange, sample reconstitution in pyridine and derivatization with BSTFA. The procedure is based on an earlier method originally reported for kraft black liquors and, in this work, is applied to identify and quantify a large slate of acidic compounds in corn stover derived alkaline pretreatment liquor (APL) as a function of pretreatment severity. Analysis of the samples is conducted with GCxGC-TOFMS to achieve good resolution of the components within the complex mixture. The results reveal the dominant low molecular weight components and their concentrations as a function of pretreatment severity. Application of this method is also demonstrated in the context of lignin conversion technologies by applying it to track the microbial conversion of an APL substrate. Here too excellent results are achieved, and the appearance and disappearance of compounds is observed in agreement with the known metabolic pathways of two bacteria, indicating the sample integrity was maintained throughout analysis. Finally, it is shown that this method applies more generally to lignin-rich materials by demonstrating its usefulness in analysis of pyrolysis oil and pyrolytic lignin.

  10. Estimating the acidity of transition metal hydride and dihydrogen complexes by adding ligand acidity constants.

    Science.gov (United States)

    Morris, Robert H

    2014-02-05

    A simple equation (pKa(THF) = ∑AL + Ccharge + Cnd + Cd6) can be used to obtain an estimate of the pKa of diamagnetic transition metal hydride and dihydrogen complexes in tetrahydrofuran, and, by use of conversion equations, in other solvents. It involves adding acidity constants AL for each of the ligands in the 5-, 6-, 7-, or 8-coordinate conjugate base complex of the hydride or dihydrogen complex along with a correction for the charge (Ccharge = -15, 0 or 30 for x = +1, 0 or -1 charge, respectively) and the periodic row of the transition metal (Cnd = 0 for 3d or 4d metal, 2 for 5d metal) as well as a correction for d(6) octahedral acids (Cd6 = 6 for d(6) metal ion in the acid, 0 for others) that are not dihydrogen complexes. Constants AL are provided for 13 commonly occurring ligand types; of these, nine neutral ligands are correlated with Lever's electrochemical ligand parameters EL. This method gives good estimates of the over 170 literature pKa values that range from less than zero to 50 with a standard deviation of 3 pKa units for complexes of the metals chromium to nickel, molybdenum, ruthenium to palladium, and tungsten to platinum in the periodic table. This approach allows a quick assessment of the acidity of hydride complexes found in nature (e.g., hydrogenases) and in industry (e.g., catalysis and hydrogen energy applications). The pKa values calculated for acids that have bulky or large bite angle chelating ligands deviate the most from this correlation. The method also provides an estimate of the base strength of the deprotonated form of the complex.

  11. Modelling of Rare Earth Elements Complexation With Humic Acid

    Science.gov (United States)

    Pourret, O.; Davranche, M.; Gruau, G.; Dia, A.

    2006-12-01

    The binding of rare earth elements (REE) to humic acid (HA) was studied by combining Ultrafiltration and ICP- MS techniques. REE-HA complexation experiments were performed at various pH conditions (ranging from 2 to 10.5) using a standard batch equilibration method. Results show that the amount of REE bound to HA strongly increase with increasing pH. Moreover, a Middle REE (MREE) downward concavity is evidenced by REE distribution patterns at acidic pH. Modelling of the experimental data using Humic Ion Binding Model VI provided a set of log KMA values (i.e. the REE-HA complexation constants specific to Model VI) for the entire REE series. The log KMA pattern obtained displays a MREE downward concavity. Log KMA values range from 2.42 to 2.79. These binding constants are in good agreement with the few existing datasets quantifying the binding of REE with humic substances except a recently published study which evidence a lanthanide contraction effect (i.e. continuous increase of the constant from La to Lu). The MREE downward concavity displayed by REE-HA complexation pattern determined in this study compares well with results from REE-fulvic acid (FA) and REE-acetic acid complexation studies. This similarity in the REE complexation pattern shapes suggests that carboxylic groups are the main binding sites of REE in HA. This conclusion is further supported by a detailed review of published studies for natural, organic-rich, river- and ground-waters which show no evidence of a lanthanide contraction effect in REE pattern shape. Finally, application of Model VI using the new, experimentally determined log KMA values to World Average River Water confirms earlier suggestions that REE occur predominantly as organic complexes (> 60 %) in the pH range between 5-5.5 and 7-8.5 (i.e. in circumneutral pH waters). The only significant difference as compared to earlier model predictions made using estimated log KMA values is that the experimentally determined log KMA values

  12. Oxygenation of Organoboronic Acids by a Nonheme Iron(II) Complex: Mimicking Boronic Acid Monooxygenase Activity.

    Science.gov (United States)

    Chatterjee, Sayanti; Paine, Tapan Kanti

    2015-10-19

    Phenolic compounds are important intermediates in the bacterial biodegradation of aromatic compounds in the soil. An Arthrobacter sp. strain has been shown to exhibit boronic acid monooxygenase activity through the conversion of different substituted phenylboronic acids to the corresponding phenols using dioxygen. While a number of methods have been reported to cleave the C-B bonds of organoboronic acids, there is no report on biomimetic iron complex exhibiting this activity using dioxygen as the oxidant. In that direction, we have investigated the reactivity of a nucleophilic iron-oxygen oxidant, generated upon oxidative decarboxylation of an iron(II)-benzilate complex [(Tp(Ph2))Fe(II)(benzilate)] (Tp(Ph2) = hydrotris(3,5-diphenyl-pyrazol-1-yl)borate), toward organoboronic acids. The oxidant converts different aryl/alkylboronic acids to the corresponding oxygenated products with the incorporation of one oxygen atom from dioxygen. This method represents an efficient protocol for the oxygenation of boronic acids with dioxygen as the terminal oxidant.

  13. Complexation of gluconic acid with Nd(III) in acidic solutions: A thermodynamic study

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhicheng [Washington State University, Pullman, WA 99164 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)], E-mail: lxzhang@wsu.edu; Bottenus, Brienne; Clark, Sue B. [Washington State University, Pullman, WA 99164 (United States); Tian Guoxin [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Zanonato, PierLuigi [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Dipartimento di Scienze Chimiche, Universita di Padova, via Marzolo 1, 35131 Padova (Italy); Rao Linfeng [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2007-10-11

    Thermodynamic properties of gluconic acid (HGH{sub 4}(aq)) complexation with Nd(III) have been studied in acidic solutions at 25 deg. C and 1.0 M NaClO{sub 4} by potentiometry, spectrophotometry and calorimetry. Three Nd(III)/gluconate complexes were identified in solutions of pC{sub H} 2.5-4.5. The formation constants and the complexation enthalpies are: log {beta}{sub 1} = 2.55 {+-} 0.05 and {delta}H{sub 1}{sup o}=-(8.22{+-}0.23)kJmol{sup -1} for Nd(GH{sub 4}){sup 2+}, log {beta}{sub 2} = 4.45 {+-} 0.05 and {delta}H{sub 2}{sup o}=-(15.3{+-}0.4)kJmol{sup -1} for Nd(GH{sub 4}){sub 2}{sup +}, and log {beta}{sub 3} = 5.60 {+-} 0.15 and {delta}H{sub 3}{sup o}=-(24.6{+-}0.6)kJmol{sup -1} for Nd(GH{sub 4}){sub 3}(aq). The thermodynamic parameters indicate that gluconic acid, like other {alpha}-hydroxycarboxylic acids, forms stronger complexes with Nd(III) than simple monocarboxylic acids, likely by the participation of the {alpha}-hydroxyl group during complexation. The same type of binding appears to occur with Ca{sup 2+} and NpO{sub 2}{sup +} as the 1:1 stability constants are linearly correlated with the effective cationic charges of the metal cations.

  14. Physical chemistry of nucleic acids and their complexes.

    Science.gov (United States)

    Ghirlando, Rodolfo; Felsenfeld, Gary

    2013-12-01

    Studies of the physical properties of nucleic acids began almost immediately following the discovery of the DNA structure. Early investigations focused on the stability and specificity of multi-strand polynucleotide complexes, then gradually on their interaction with other molecules, particularly proteins. As molecular and structural biology expanded to provide detailed information about biochemical mechanisms, physical studies eventually acquired the additional constraint that they should be relevant to functioning biological systems. We describe work in our laboratory that began with investigations of relatively simple questions about the role of electrostatic interactions in the stabilization of multi-strand nucleic acid structures, and evolved to studies of chromatin structure in vitro and within the nucleus. Copyright © 2013 Wiley Periodicals, Inc.

  15. Injectable hydrogels derived from phosphorylated alginic acid calcium complexes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han-Sem; Song, Minsoo, E-mail: minsoosong00@gmail.com; Lee, Eun-Jung; Shin, Ueon Sang, E-mail: usshin12@dankook.ac.kr

    2015-06-01

    Phosphorylation of sodium alginate salt (NaAlg) was carried out using H{sub 3}PO{sub 4}/P{sub 2}O{sub 5}/Et{sub 3}PO{sub 4} followed by acid–base reaction with Ca(OAc){sub 2} to give phosphorylated alginic acid calcium complexes (CaPAlg), as a water dispersible alginic acid derivative. The modified alginate derivatives including phosphorylated alginic acid (PAlg) and CaPAlg were characterized by nuclear magnetic resonance spectroscopy for {sup 1}H, and {sup 31}P nuclei, high resolution inductively coupled plasma optical emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. CaPAlg hydrogels were prepared simply by mixing CaPAlg solution (2 w/v%) with NaAlg solution (2 w/v%) in various ratios (2:8, 4:6, 6:4, 8:2) of volume. No additional calcium salts such as CaSO{sub 4} or CaCl{sub 2} were added externally. The gelation was completed within about 3–40 min indicating a high potential of hydrogel delivery by injection in vivo. Their mechanical properties were tested to be ≤ 6.7 kPa for compressive strength at break and about 8.4 kPa/mm for elastic modulus. SEM analysis of the CaPAlg hydrogels showed highly porous morphology with interconnected pores of width in the range of 100–800 μm. Cell culture results showed that the injectable hydrogels exhibited comparable properties to the pure alginate hydrogel in terms of cytotoxicity and 3D encapsulation of cells for a short time period. The developed injectable hydrogels showed suitable physicochemical and mechanical properties for injection in vivo, and could therefore be beneficial for the field of soft tissue engineering. - Highlights: • Preparation of water-soluble alginic acid complexes with calcium phosphate • Self-assembly of the phosphorylated alginic acid calcium complexes with sodium alginate • Preparation of injectable hydrogels with diverse gelation times within about 3–40 min.

  16. [PREPARATIONS OF PAMIDRONOVIC ACID IN COMPLEX TREATMENT ON OSTEOGENESIS IMPERFECTA].

    Science.gov (United States)

    Zyma, A M; Guk, Yu M; Magomedov, O M; Gayko, O G; Kincha-Polishchuk, T A

    2015-07-01

    Modern view of drug therapy in the complex treatment of orthopedic manifestations of osteogenesis imperfecta (OI) was submitted. Developed and tested system of drug correction of structural and functional state of bone tissue (BT) using drugs pamidronovic acid, depending on osteoporosis severity and type of disease. Such therapy is appropriate to apply both independently and in conjunction with surgery to correct deformations of long bones of the lower extremities. Effectiveness and feasibility of the proposed methods of drug therapy was proved, most patients resume features walking and support.

  17. Formation and characterization of thioglycolic acid-silver cluster complexes.

    Science.gov (United States)

    Bellina, Bruno; Antoine, Rodolphe; Broyer, Michel; Gell, Lars; Sanader, Željka; Mitrić, Roland; Bonačić-Koutecký, Vlasta; Dugourd, Philippe

    2013-06-21

    Gas phase reactivity observed in an ion trap was used to produce silver clusters protected with thioglycolic acid. Fragmentation pathways as well as optical properties were explored experimentally and theoretically. Sequential losses of SCH2 and CO2 in the ion trap lead to redox reactions with charge transfers between the metal part and the carboxylate and thiolate groups. This allows us to control the number of electrons in the metallic subunit and thus optical properties of the complexes. The presented formation process can be used as a prototype for tuning optical and chemical properties of ligated metal clusters by varying the number of confined electrons within the metallic subunit.

  18. Complexes of light lanthanides with 2,3-dimethoxybenzoic acid

    Directory of Open Access Journals (Sweden)

    AGNIESZKA WALKÓW-DZIEWULSKA

    2001-08-01

    Full Text Available The complexes of light lanthanides with 2,3-dimethoxybenzoic acid of the formula: Ln(C9H9O43, where Ln = La(III, Ce(III, Pr(III, Nd(III, Sm(III, Eu(III and Gd(III have been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric studies, as well as X-ray and magnetic measurements. The complexes have colours typical for Ln3+ ions (La, Ce, Eu, Gd–white, Sm–cream, Pr–green, Nd–violet. The carboxylate group in these complexes is a bidentate, chelating ligand or a tridentate chelating and bridging one. They are crystalline compounds characterized by low symmetry. On heating in air to 1173 K, the 2,3-dimethoxybenzoates of the light lanthanides decompose in various ways. The complexes of Ce(III, Pr(III, Sm(III, Eu(III and Gd(III decompose directly to oxides of the respective metals while those of La(III and Nd(III via the intermediate formation of La2O2CO3 and Nd2O2CO3. The solubilities of the 2,3-dimethoxybenzoates of the light lanthanides in water at 293 K are in the orders of 10-3 – 10-2 mol dm-3. The magnetic moments were determined in the range 4.2–298 K and the complexes are found to obey the Curie-Weiss law.

  19. Investigation of molecular interactions in the complex formation of tartaric acid derivatives with di(2-ethylhexyl) phosphoric acid

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The molecular interactions in the complex formation of two tartaric acid derivatives with di(2-ethylhexyl) phosphoric acid are investigated. The complex formation with a 1:1 stoichiometry between tartaric acid derivatives and D2EHPA can be obtained through UV-Vis titration, NMR chemical shifts and molecular dynamic simulations. Furthermore, the differences of the two complexes on the binding constants and strength of hydrogen bonds can also be determined. Such research will ideally provide insight into ways of regulating the complex forming properties of tartaric acid derivatives for composing or syn- thesizing new chiral resolving agents.

  20. Investigation of molecular interactions in the complex formation of tartaric acid derivatives with di(2-ethylhexyl) phosphoric acid

    Institute of Scientific and Technical Information of China (English)

    TAN Bin; ZHAI Zheng; LUO GuangSheng; WANG JiaDing

    2008-01-01

    The molecular interactions in the complex formation of two tartaric acid derivatives with di(2-ethylhexyl) phosphoric acid are investigated. The complex formation with a 1:1 stoichiometry between tartaric acid derivatives and D2EHPA can be obtained through UV-Vis titration, NMR chemical shifts and molecular dynamic simulations. Furthermore, the differences of the two complexes on the binding constants and strength of hydrogen bonds can also be determined. Such research will ideally provide insight into ways of regulating the complex forming properties of tartaric acid derivatives for composing or syn-thesizing new chiral resolving agents.

  1. Oral absorption of hyaluronic acid and phospholipids complexes in rats

    Institute of Scientific and Technical Information of China (English)

    Si-Ling Huang; Pei-Xue Ling; Tian-Min Zhang

    2007-01-01

    AIM: To prepare a complex of hyaluronic acid (HA) and phospholipids (PL), and study the improvement effect of PL on the oral absorption of HA.METHODS: The complex of HA-PL (named Haplex) was prepared by film dispersion and sonication method, its physico-chemical properties were identified by infrared spectra and differential scanning calorimetry (DSC). The oral absorption of Haplex was studied. Thirty-two healthy rats were divided into 4 groups randomly: (1) a normal saline (NS) control group; (2) an HA group; (3) a mixture group and (4) a Haplex group. After intragastric administration, the concentration of HA in serum was determined.RESULTS: The physico-chemical properties of Haplex were different from HA or PL or their mixture. After Haplex was administered to rats orally, the serum concentration of HA was increased when compared with the mixture or HA control groups from 4 h to 10 h (P < 0.05). The ΔAUCo-12 h of Haplex was also greater than that of the other three groups (P < 0.05).CONCLUSION: The method of film dispersion and sonication can prepare HA and PL complex, and PL can enhance the oral absorption of exogenous HA.

  2. Syntheses,characteristics,and fluorescence properties of complexes of europium with benzoic acid and its derivatives

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhongcheng; SHU Wangen; RUAN Jianming; HUANG Boyun; LIU Younian

    2004-01-01

    The binary complexes of europium with benzoic acid and its derivatives (phthalic acid, m-phthalic acid,o-aminobenzoic acid, salicylic acid, and sulfosalicylic acid) were synthesized and their compositions were identified by elemental analyses. UV and IR of the complexes have been investigated. The UV spectra indicated that the complexes' ultraviolet absorption were mainly the ligands' absorption. The IR spectra showed that the IR spectra of complexes are different from those of free ligands. The fluorescence properties of them were investigated by using luminescence spectroscopy, the results showed that only three complexes appear as better luminescence, they were Eu-benzoic acid,Eu-m-phthalic acid and Eu-phthalic acid, while the others exhibited the ligands' wideband emission.

  3. Complexation of uranium(VI) with aromatic acids in aqueous solution. A comparison of hydroxamic acids and benzoic acid

    Energy Technology Data Exchange (ETDEWEB)

    Glorius, M.; Moll, H.; Bernhard, G. [Forschungszentrum Dresden-Rossendorf e.V., Dresden (Germany). Inst. fuer Radiochemie

    2007-07-01

    The complex formation of uranium(VI) with salicylhydroxamic,benzohydroxamic, and benzoic acid in 0.1 M NaClO{sub 4} was studied by UV-vis spectroscopy at pH 3 and 4. Uranium(VI) species of the type M{sub p}L{sub q}H{sub r} were identified from the UV-vis spectra in all three systems. An increase in the absorption combined with a blue shift of the absorption maxima in comparison to the bands of the free uranyl ion of 22.5 {+-} 2 nm was observed in the uranium (VI)-salicylhydroxamic acid-system. Besides indications for a 1:2 complex, the formation of a 1:1 complex with a stability constant of log {beta}{sub 111} = 17.12 {+-} 0.10 could be demonstrated by its individual absorption spectrum and molar absorption coefficient. Also in the uranium(VI)-benzohydroxamic acid-system a blue shift of the absorption maxima in comparison to the bands of the free uranyl ion of 27 {+-} 1.4 nm indicate the complex formation. The stability constants are log {beta}{sub 110} = 7.96 {+-} 0.05 for UO{sub 2}[C{sub 6}H{sub 4}CONHO]{sup +} and log {beta}{sub 120} = 15.25 {+-} 0.11 for UO{sub 2}[C{sub 6}H{sub 4}CONHO]{sub 2}. In contrast to the hydroxamic acids, benzoic acid shows a red shift of the absorption maxima of 2.5 {+-} 2 nm. Only the 1:1 complex UO{sub 2}[C{sub 6}H{sub 4}COO]{sup +} with a stability constant of log {beta}{sub 110} = 3.37 {+-} 0.14 is existent. An estimate is made in order to discuss the dependencies observed in the absorption spectra in relation to possible coordination modes of uranium(VI). The strength of the complex formation between uranyl and the three aromatic acids is discussed. (orig.)

  4. Polarographic study of complexing in the molybdenum (6) - mandelic acid - sulphuric acid system

    Energy Technology Data Exchange (ETDEWEB)

    Zaitsev, P.M.; Zaitseva, Z.V.; Zhdanov, S.I.; Nikolaeva, T.D. (Vsesoyuznyj Nauchno-Issledovatel' skij Inst. Okhrany Truda, Moscow (USSR); Vsesoyuznyj Nauchno-Issledovatel' skij Inst. Khimicheskikh Reaktivov i Osobo Chistykh Veshchestv, Moscow (USSR))

    1980-09-01

    The studies of polarographic behaviour of molybdenum (6) in 0.05-2.5 M H/sub 2/SO/sub 4/ solutions, containing mandelic acid (HL), has shown that molybdenum (6) is reduced via two steps in the presence of HL. One electron is transferred in 0.05 M H/sub 2/SO/sub 4/ during the first step and two during the second one; one electron during each step is transferred if Csub(Hsub(2)SOsub(4))>=0.5 M. Such a difference is suggested to be due to the formation of a mixed-ligand complex MoO/sub 2/xHLx(H/sub 2/SO/sub 4/)/sup +/ which is reduced stepwise, one electron participating at each step. The complex formation is slow. The complex formation constant has been calculated to be 30+-2.7.

  5. Centrosymmetric dimer of quinuclidine betaine and squaric acid complex

    Science.gov (United States)

    Dega-Szafran, Z.; Katrusiak, A.; Szafran, M.

    2012-12-01

    The complex of squaric acid (3,4-dihydroxy-3-cyclobuten-1,2-dion, H2SQ) with quinuclidine betaine (1-carboxymethyl-1-azabicyclo[2.2.2]octane inner salt, QNB), 1, has been characterized by single-crystal X-ray analysis, FTIR and NMR spectroscopies and by DFT calculations. In the crystal of 1, monoclinic space group P21/n, one proton from H2SQ is transferred to QNB. QNBH+ and HSQ- are linked together by a Osbnd H⋯O hydrogen bond of 2.553(2) Å. Two such QNBH+·HSQ- complexes form a centrosymmetric dimer bridged by two Osbnd H⋯O bonds of 2.536(2) Å. The FTIR spectrum is consistent with the X-ray results. The structures of monomer QNBH+·HSQ- (1a) and dimer [QNB·H2SQ]2 (2) have been optimized at the B3LYP/6-311++G(d,p) level of theory. Isolated dimer 2 optimized back to a molecular aggregate of H2SQ and QNB. The calculated frequencies for the optimized structure of dimer 2 have been used to explain the frequencies of the experimental FTIR spectrum. The interpretation of 1H and 13C NMR spectra has been based on the calculated GIAO/B3LYP/6-311++G(d,p) magnetic isotropic shielding constants for monomer 1a.

  6. Synthesis and spectroscopic characterization of fluorescent solid rare earth complexes with hydroxamic acids

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The complexes RE2(DHYA)3 .nH2O in the title bar were synthesized through some reactions oftrivalent rareearth ions. In the process of synthesis, dihydroxamic acids were taken as ligands while the alcohol was taken as a solvent.The ligands included adipylhydroxamic acid (ADHA), p-phthalichydroxamic acid (PPHA), oxalohydroxamic acid (OXHA), butadihydroxamic acid (BDHA), o-phthalichydroxamic acid (OPHA), benzoylhydroxamic acid (BHA), etc.Measured at 25 ℃, the molar conductances in various modes are 13.00-21.05 S. cm2. mol-1, which shows that rare-earth complexes are nonelectrolytes and the hydroxamino groups of the complexes have taken part in bonding. Infrared spectra, ultraviolet spectra, nuclear magnetic resonance (1HNMR) spectra, and fluorescence spectra were used to investigate the complexes. Experiments have proved that the complexes of Eu3+ and Tb3+ with aromatic hydroxamic acids have good fluorescent characteristics.

  7. 40 CFR 721.10089 - Modified salicylic acid, zirconium complex (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified salicylic acid, zirconium... Specific Chemical Substances § 721.10089 Modified salicylic acid, zirconium complex (generic). (a) Chemical... as modified salicylic acid, zirconium complex (PMN P-00-552) is subject to reporting under...

  8. Structural basis for the dysfunctioning of human 2-oxo acid dehydrogenase complexes

    NARCIS (Netherlands)

    Hengeveld, A.F.; Kok, de A.

    2002-01-01

    2-oxo acid dehydrogenase complexes are a ubiquitous family of multienzyme systems that catalyse the oxidative decarboxylation of various 2-oxo acid substrates. They play a key role in the primary energy metabolism: in glycolysis (pyruvate dehydrogenase complex), the citric acid cycle (2-oxoglutarate

  9. Facile Synthesis and Structural Characterization of Amylose-Fatty Acid Inclusion Complexes

    NARCIS (Netherlands)

    Cao, Zheng; Woortman, Albert; Rudolf, Petra; Loos, Katja

    2015-01-01

    Amylose-fatty acid inclusion complexes can be easily prepared by simple mixing in hot aqueous solutions. Above a critical chain length (C6) of the fatty acid insoluble complexes between amylose and each fatty acid (C8, C10, C12, C14, C16) were precipitated from the solution, and characterized by FT-

  10. Structural basis for the dysfunctioning of human 2-oxo acid dehydrogenase complexes

    NARCIS (Netherlands)

    Hengeveld, A.F.; Kok, de A.

    2002-01-01

    2-oxo acid dehydrogenase complexes are a ubiquitous family of multienzyme systems that catalyse the oxidative decarboxylation of various 2-oxo acid substrates. They play a key role in the primary energy metabolism: in glycolysis (pyruvate dehydrogenase complex), the citric acid cycle (2-oxoglutarate

  11. Molecular complexes of alprazolam with carboxylic acids, boric acid, boronic acids, and phenols. Evaluation of supramolecular heterosynthons mediated by a triazole ring.

    Science.gov (United States)

    Varughese, Sunil; Azim, Yasser; Desiraju, Gautam R

    2010-09-01

    A series of molecular complexes, both co-crystals and salts, of a triazole drug-alprazolam-with carboxylic acids, boric acid, boronic acids, and phenols have been analyzed with respect to heterosynthons present in the crystal structures. In all cases, the triazole ring behaves as an efficient hydrogen bond acceptor with the acidic coformers. The hydrogen bond patterns exhibited with aromatic carboxylic acids were found to depend on the nature and position of the substituents. Being a strong acid, 2,6-dihydroxybenzoic acid forms a salt with alprazolam. With aliphatic dicarboxylic acids alprazolam forms hydrates and the water molecules play a central role in synthon formation and crystal packing. The triazole ring makes two distinct heterosynthons in the molecular complex with boric acid. Boronic acids and phenols form consistent hydrogen bond patterns, and these are seemingly independent of the substitutional effects. Boronic acids form noncentrosymmetric cyclic synthons, while phenols form O--H...N hydrogen bonds with the triazole ring.

  12. Copper(II and lead(II complexation by humic acid and humic-like ligands

    Directory of Open Access Journals (Sweden)

    IVANA KOSTIĆ

    2011-09-01

    Full Text Available The stability of metal–humate complexes is an important factor determining and predicting speciation, mobility and bioavailability of heavy metals in the environment. A comparative investigation of the complexation of Cu(II and Pb(II with humic acid and humic-like ligands, such as benzoic and salicylic acid, was performed. The analysis was realized at pH 4.0, a temperature of 25 °C and at an ionic strength of 0.01 mol dm-3 (NaCl using the Schubert ion-exchange method and its modified form. The stability constants were calculated from the experimental data by the Schubert method for complexes with benzoic and humic acid. A modified Schubert method was used for the determination of the stability constants of the complexes with salicylic acid. It was found that Cu(II and Pb(II form mononuclear complexes with benzoic and humic acid while with salicylic acid both metals form polynuclear complexes. The results indicate that Pb(II has a higher binding ability than Cu(II to all the investigated ligands. The Cu(II–salicylate and Pb(II–salicylate complexes showed noticeable higher stability constants compared with their complexes with humic acid, while the stabilities of the complexes with benzoic acid differed less. Salicylic and benzoic acids as humic-like ligands can be used for setting the range of stability constants of humic complexes with Cu(II and Pb(II.

  13. Glucose-lowering Activity of Amino Acid-N-phosphonic Acid Oxovanadium Complexes and Its Interaction with DNA

    Institute of Scientific and Technical Information of China (English)

    LIU, Ju-Tao; FAN, Sheng-Di; LI, Chuan-Bi; LI, De-Qian

    2006-01-01

    Vanadium has well-documented lowering glucose properties both in vitro and in vivo. The design of new oxovanadium(Ⅳ) coordination compounds, intended for use as insulin-enhancing agents in the treatment of diabetes mellitus, can potentially benefit from a synergistic approach, in which the whole complex has more than an additive effect from its component parts. Biological testing with oxovanadium(Ⅳ) organic phosphonic acid, for insulin-enhancing potential included acute administration, by oral gavage in streptozotocin (STZ) diabetic rats. The complexes of oxovanadium(Ⅳ) amino acid-N-phosphonic acid exhibit higher lowering glucose activity in vivo. The interaction of the complexes of oxovanadium(Ⅳ) amino acid-N-phosphonic acid with DNA was investigated by agarose gel electrophoresis. The results indicated that these complexes have strong interaction with DNA.

  14. Morphological characteristics, oxidative stability and enzymic hydrolysis of amylose-fatty acid complexes.

    Science.gov (United States)

    Marinopoulou, Anna; Papastergiadis, Efthimios; Raphaelides, Stylianos N; Kontominas, Michael G

    2016-05-05

    Complexes of amylose with fatty acids varying in carbon chain length and degree of unsaturation were prepared at 30, 50 or 70°C by dissolving amylose in 0.1N KOH and mixing with fatty acid potassium soap solution. The complexes were obtained in solid form as precipitates after neutralization. SEM microscopy revealed that the morphology of the complexes was that of ordered lamellae separated from amorphous regions whereas confocal laser scanning microscopy showed images of the topography of the guest molecules in the complex matrix. FTIR spectroscopy revealed that the absorption peak attributed to carbonyl group of free fatty acid was shifted when the fatty acid was in the form of amylose complex. Thermo-gravimetry showed that the unsaturated fatty acids were effectively protected from oxidation when they were complexed with amylose whereas enzymic hydrolysis experiments showed that the guest molecules were quantitatively released from the amylose complexes.

  15. Complexation of NpO2+ with N-methyl-iminodiacetic Acid: in Comparison with Iminodiacetic and Dipicolinic Acids

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Guoxin; Rao, Linfeng

    2010-10-01

    Complexation of Np(V) with N-methyl-iminodiacetic acid (MIDA) in 1 M NaClO{sub 4} solution was studied with multiple techniques including potentiometry, spectrophotometry, and microcalorimetry. The 1:2 complex, NpO{sub 2}(MIDA){sub 2}{sup 3-} was identified for the first time in aqueous solution. The correlation between its optical absorption properties and symmetry was discussed, in comparison with Np(V) complexes with two structurally related nitrilo-dicarboxylic acids, iminodiacetic acid (IDA) and dipicolinic acid (DPA). The order of the binding strength (DPA > MIDA > IDA) is explained by the difference in the structural and electronic properties of the ligands. In general, the nitrilo-dicarboxylates form stronger complexes with Np(V) than oxy-dicarboxylates due to a much more favorable enthalpy of complexation.

  16. Complex modulation of androgen responsive gene expression by methoxyacetic acid

    Directory of Open Access Journals (Sweden)

    Stanley Kerri A

    2011-03-01

    Full Text Available Abstract Background Optimal androgen signaling is critical for testicular development and spermatogenesis. Methoxyacetic acid (MAA, the primary active metabolite of the industrial chemical ethylene glycol monomethyl ether, disrupts spermatogenesis and causes testicular atrophy. Transcriptional trans-activation studies have indicated that MAA can enhance androgen receptor activity, however, whether MAA actually impacts the expression of androgen-responsive genes in vivo, and which genes might be affected is not known. Methods A mouse TM3 Leydig cell line that stably expresses androgen receptor (TM3-AR was prepared and analyzed by transcriptional profiling to identify target gene interactions between MAA and testosterone on a global scale. Results MAA is shown to have widespread effects on androgen-responsive genes, affecting processes ranging from apoptosis to ion transport, cell adhesion, phosphorylation and transcription, with MAA able to enhance, as well as antagonize, androgenic responses. Moreover, testosterone is shown to exert both positive and negative effects on MAA gene responses. Motif analysis indicated that binding sites for FOX, HOX, LEF/TCF, STAT5 and MEF2 family transcription factors are among the most highly enriched in genes regulated by testosterone and MAA. Notably, 65 FOXO targets were repressed by testosterone or showed repression enhanced by MAA with testosterone; these include 16 genes associated with developmental processes, six of which are Hox genes. Conclusions These findings highlight the complex interactions between testosterone and MAA, and provide insight into the effects of MAA exposure on androgen-dependent processes in a Leydig cell model.

  17. Thermodynamics of the complexation of arabinogalactan with salicylic and p-aminobenzoic acids in aqueous solutions

    Science.gov (United States)

    Mudarisova, R. Kh.; Badykova, L. A.

    2016-03-01

    The thermodynamics of complexation of arabinogalactan with salicylic and p-aminobenzoic acids in aqueous solutions is studied by means spectroscopy. The standard thermodynamic characteristics (Δ H°; Δ G°; Δ S°) of complexation are calculated.

  18. Effects of chemical and enzymatic modifications on starch-linoleic acid complex formation.

    Science.gov (United States)

    Arijaje, Emily Oluwaseun; Wang, Ya-Jane

    2017-02-15

    This study investigated the complexation yield and physicochemical properties of soluble and insoluble starch complexes with linoleic acid when a β-amylase treatment was applied to acetylated and debranched potato starch. The degree of acetylation was generally higher in the soluble complexes than in the insoluble ones. The insoluble complexes from the acetylated starch displayed the V-type pattern, whereas, the soluble complexes displayed a mixture of either the A-/V-type or the B-/V-type pattern. Acetylation decreased onset and peak melting temperatures for the insoluble complexes, whereas no melting endotherm was observed in the soluble complexes. Acetylation substantially increased the amount of complexed linoleic acid in the insoluble complexes, but had little positive effect on the formation of the soluble complexes. The β-amylase treatment significantly increased the complexed linoleic content in both soluble and insoluble complexes for the low acetylated starch, but not for the high acetylated starch.

  19. Amylose inclusion complexation of ferulic acid via lipophilization

    Science.gov (United States)

    Ferulic acid is an interesting phytochemical that exhibits antioxidant, anti-inflammatory, antimicrobial, UV-absorber, and anticarcinogenic activities. These properties make it of interest in food formulations, cosmetics, polymer, and pharmaceutical applications. However, delivery of ferulic acid in...

  20. Complex Formation of Selected Radionuclides with Ligands Commonly Found in Ground Water: Low Molecular Organic Acids

    DEFF Research Database (Denmark)

    Jensen, Bror Skytte; Jensen, H.

    1985-01-01

    A general approach to the analysis of potentiometric data on complex formation between cations and polybasic amphoteric acids is described. The method is used for the characterisation of complex formation between Cs+, Sr2+, Co2+, La 3+, and Eu3+ with a α-hydroxy acids, tartaric acid and citric ac......, and with the α-amino acids, aspartic acid and L-cysteine. The cations have been chosen as typical components of reactor waste, and the acids because they are often found as products of microbial activity in pits or wherever organic material decays...

  1. Brønsted-Lowry Acid Strength of Metal Hydride and Dihydrogen Complexes.

    Science.gov (United States)

    Morris, Robert H

    2016-08-10

    Transition metal hydride complexes are usually amphoteric, not only acting as hydride donors, but also as Brønsted-Lowry acids. A simple additive ligand acidity constant equation (LAC for short) allows the estimation of the acid dissociation constant Ka(LAC) of diamagnetic transition metal hydride and dihydrogen complexes. It is remarkably successful in systematizing diverse reports of over 450 reactions of acids with metal complexes and bases with metal hydrides and dihydrogen complexes, including catalytic cycles where these reactions are proposed or observed. There are links between pKa(LAC) and pKa(THF), pKa(DCM), pKa(MeCN) for neutral and cationic acids. For the groups from chromium to nickel, tables are provided that order the acidity of metal hydride and dihydrogen complexes from most acidic (pKa(LAC) -18) to least acidic (pKa(LAC) 50). Figures are constructed showing metal acids above the solvent pKa scales and organic acids below to summarize a large amount of information. Acid-base features are analyzed for catalysts from chromium to gold for ionic hydrogenations, bifunctional catalysts for hydrogen oxidation and evolution electrocatalysis, H/D exchange, olefin hydrogenation and isomerization, hydrogenation of ketones, aldehydes, imines, and carbon dioxide, hydrogenases and their model complexes, and palladium catalysts with hydride intermediates.

  2. Synthesis, Characterization of α-Oxopentanedioic Acid-Isonicotinoyl Hydrazone Rare Earth-Complexes and Relaxivity of Gd-complex

    Institute of Scientific and Technical Information of China (English)

    杨正银; 杨汝栋

    2004-01-01

    α-Oxopentanedioic acid isonicotinoyl hydrazone (H2L) and its five rare earth complexes were synthesized with a view to further investigating MRI activities of the polycarboxylic Schiff base complexes. The complexes were characterized on the basis of elemental analyses, IR, UV, 1H NMR spectra and thermal analyses. The general formula of the complexes is [Ln(HL)(H2O)2]Cl2·H2O (where Ln(Ⅲ)=La, Pr, Nd, Eu and Gd). In addition, the relaxivity (R1) of the Gd-complex was determined by INVREC Au program.

  3. Study of Complexes of Lanthanum with Amino Acids by Titration Calorimeter

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The stability constants and thermodynamic functions for complexes of lanthanum with eight kind of amino acids according to 1:1 and 1:2 in proportion have been determined by titration calorimeter at 298. 15 K. The enthalpy change makes a predominant contribution to the stability of these complexes. The ring in amino acid associated with lanthanum ion helps to enhance the stability of complexes. Steric effectsbetween rings in complexes leads to that the equilibrium constants of reaction of the complexes (1:2) ismuch less than that of the complexes (l:1).

  4. Intramolecular deactivation processes in complexes of salicylic acid or glycolic acid with Eu(III).

    Science.gov (United States)

    Kuke, S; Marmodée, B; Eidner, S; Schilde, U; Kumke, M U

    2010-04-01

    The complexation of Eu(III) by 2-hydroxy benzoic acid (2HB) or glycolic acid (GL) was investigated using steady-state and time-resolved laser spectroscopy. Experiments were carried out in H(2)O as well as in D(2)O in the temperature range of 80Kluminescence spectra and luminescence decay times were evaluated with respect to the temperature dependence of (i) the luminescence decay time tau, (ii) the energy of the D5(0)-->F7(0) transition, (iii) the width of the D5(0)-->F7(0) transition, and (iv) the asymmetry ratio calculated from the luminescence intensities of the D5(0)-->F7(2) and D5(0)-->F7(1) transition, respectively. The differences in ligand-related luminescence quenching are discussed. Based on the temperature dependence of the luminescence decay times an activation energy for the ligand-specific non-radiative deactivation in Eu(III)-2HB or Eu(III)-GL complexes was determined. It is stressed that ligand-specific quenching processes (other than OH quenching induced by water molecules) need to be determined and considered in detail, in order to extract speciation-relevant information from luminescence data (e.g., estimation of the number of water molecules n(H(2)0) in the first coordination sphere of Eu(III)). In case of 2HB, conclusions drawn from the evaluation of the Eu(III) luminescence are compared with results of a X-ray structure analysis. Copyright 2010 Elsevier B.V. All rights reserved.

  5. Corrigendum: Structural diversity of target-specific homopyrimidine peptide nucleic acid-dsDNA complexes

    DEFF Research Database (Denmark)

    Bentin, T.; Hansen, G.I.; Nielsen, P.E.

    2007-01-01

    This corrects the article "Structural diversity of target-specific homopyrimidine peptide nucleic acid-dsDNA complexes" in volume 34 on page 5790.......This corrects the article "Structural diversity of target-specific homopyrimidine peptide nucleic acid-dsDNA complexes" in volume 34 on page 5790....

  6. Fluorescence of complexes of Eu( Ⅱ ) with aromatic carboxylic acid-1, 1O-phenanthroline

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The 1, 10-phenanthroline-aromatic carboxylic acid (benzoic acid and o-phthalic acid) binary and ternary complexes of europium were synthesized. The fluorescence and FT-IR spectroscopy, elemental analysis, UV spectroscopic studies on these complexes were also performed. These complexes can emit strong red fluorescence of Eu( m ) excited by UV light. At the same excited wavelength, the fluorescence spectra of the complexes were also studied. The results indi cated that the fluorescence intensities of ternary complexes are stronger than that of binary complexes. The reason is that phenanthroline has higher electron density and higher orbit scope in the conjugated system and consequently an easier ener gy transfer to the europium ion, which makes the fluorescence intensity of ternary complexes be stronger than that of bi nary complexes.

  7. Asymmetric synthesis of amino acid precursors in interstellar complex organics by circularly polarized light

    OpenAIRE

    Takano, Yoshinori; Takahashi, Jun-ichi; Kaneko, Takeo; Marumo, Katsumi; Kobayashi, Kensei

    2007-01-01

    The asymmetric synthesis of amino acid precursors from complex organics have been performed. A gaseous mixture of carbon monoxide, ammonia and water (molecules which are among those identified in the interstellar medium) was irradiated with 3.0 MeV protons to obtain amino acid precursors within high-molecular-weight complex organics of up to 3,000 Da. The amino acid precursor products synthesized were then irradiated with right (R-) or left (L-) ultraviolet circularly polarized light (UV-CPL)...

  8. Electron Transfer Studies of Ruthenium(II) Complexes with Biologically Important Phenolic Acids and Tyrosine.

    Science.gov (United States)

    Rajeswari, Angusamy; Ramdass, Arumugam; Muthu Mareeswaran, Paulpandian; Rajagopal, Seenivasan

    2016-03-01

    The ruthenium(II) complexes having 2,2'-bipyridine and phenanthroline derivatives are synthesized and characterized. The photophysical properties of these complexes at pH 12.5 are studied. The electron transfer reaction of biologically important phenolic acids and tyrosine are studied using absorption, emission and transient absorption spectral techniques. Semiclassical theory is applied to calculate the rate of electron transfer between ruthenium(II) complexes and biologically important phenolic acids.

  9. Washing powders and the environment: has TAED any influence on the complexing behaviour of phosphonic acids?

    Science.gov (United States)

    Deluchat, Véronique; Lacour, Stella; Serpaud, Bernard; Bollinger, Jean-Claude

    2002-10-01

    Complexation properties of two phosphonic acids: nitrilotris (methylenephosphonic acid) and 1-hydroxyethane-1,1'-diphosphonic acid, with Cu(II) and Ca(II) have been previously determined by pH and ionic selective electrode titrations. These phosphonic acids are commonly added to washing powders as polyphosphate substitutes and are here studied in the presence of another detergent compound: tetraacetylethylenediamine (TAED), a bleaching activator. Product concentrations were chosen in order to correspond to component concentration ratios encountered in washing powders. Potentiometric titrations were carried out to determine the possible TAED interferences; they indicate that TAED and its by-products have no action on phosphonic acid complexing behaviour. Under our experimental conditions, the action of TAED was modelled with acetic acid and ethylenediamine, the final by-products of TAED hydrolysis. If we take into account both phosphonic and acetic acids, speciation diagrams corresponding to representative fresh water systems showed that the acetic acid does not influence cation speciation.

  10. Antioxidant activity of bovine serum albumin binding amino acid Schiff-bases metal complexes

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Glutamic acid-salicylaldehyde Schiff-base metal complexes are bound into bovine serum albumin (BSA), which afforded BSA binding Schiff-base metal complexes (BSA-SalGluM, M=Cu, Co, Ni, Zn). The BSA binding metal complexes were characterized by UV-vis spectra and Native PAGE. It showed that the protein structures of BSA kept after coordinating amino acid Schiff-bases metal complexes. The effect of the antioxidant activity was investigated. The results indicate that the antioxidant capacity of BSA increased more than 10 times after binding Schiff-base metal complexes.

  11. Synthesis and spectroscopic characterization of gallic acid and some of its azo complexes

    Science.gov (United States)

    Masoud, Mamdouh S.; Hagagg, Sawsan S.; Ali, Alaa E.; Nasr, Nessma M.

    2012-04-01

    A series of gallic acid and azo gallic acid complexes were prepared and characterized by elemental analysis, IR, electronic spectra and magnetic susceptibility. The complexes were of different geometries: Octahedral, Tetrahedral and Square Planar. ESR was studied for copper complexes. All of the prepared complexes were of isotropic nature. The thermal analyses of the complexes were studied by DTA and DSC techniques. The thermodynamic parameters and the thermal transitions, such as glass transitions, crystallization and melting temperatures for some ligands and their complexes were evaluated and discussed. The entropy change values, ΔS#, showed that the transition states are more ordered than the reacting complexes. The biological activities of some ligands and their complexes are tested against Gram positive and Gram negative bacteria. The results showed that some complexes have a well considerable activity against different organisms.

  12. [Amino acid composition of polynucleotide-peptide complexes isolated from algae].

    Science.gov (United States)

    Pusheva, M A; Khoreva, M A

    1977-01-01

    The amino acid composition of the peptide moiety of sulphur containing polynucleotide-peptide complexes (S-PNPC) was studied with four species of green algae and two species of blue-green algae. S-PNPC contained almost all amino acids which were usually encountered in acid hydrolysates of proteins, and also unidentified ninhydrin-positive compounds. The amino acid composition of the peptide moiety of S-PNPC was rather similar in the case of different algae, and was characterized by the prevailence of acid amino acids.

  13. Syntheses,characteristics and fluorescence properties of complexes of terbium with benzoic acid and its derivatives

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhong-cheng; SHU Wan-gen; RUAN Jian-ming; HUANG Bai-yun; LIU You-nian

    2005-01-01

    The binary complexes of terbium with benzoic acid and its derivatives (phthalic acid,iso-phthalic acid,oaminobenzoic acid,salicylic acid,sulfosalicylic acid) were synthesized and their compositions were identified by elemental analyses.UV,IR of the complexes were investigated.The UV spectra indicate that the complexes'ultraviolet absorption is mainly the ligands' absorption,but the location of peak drifts.The IR spectra show that the IR spectra of complexes are different from those of free ligands,and the band at 400-500 cm-1,due to the stretching vibration of Tb-O,is absent for free ligands.The fluorescence properties were investigated by using luminescence spectroscope,the results show that all the six complexes of terbium exhibit excellent luminescence,due to the transition from the lowest excited state 5D4 to 7F ground state manifold,the complexes of terbium with sulfosalicylic acid have the strongest fluorescence intensity,and is stronger than o-aminobenzoic acid-terbium,whose fluorescence intensity is regarded as the strongest one in the literature,and even stronger than some phosphor of terbium.

  14. Design of stereoelectronically promoted super lewis acids and unprecedented chemistry of their complexes.

    Science.gov (United States)

    Foroutan-Nejad, Cina; Vicha, Jan; Marek, Radek

    2014-09-01

    A new family of stereoelectronically promoted aluminum and scandium super Lewis acids is introduced on the basis of state-of-the-art computations. Structures of these molecules are designed to minimize resonance electron donation to central metal atoms in the Lewis acids. Acidity of these species is evaluated on the basis of their fluoride-ion affinities relative to the antimony pentafluoride reference system. It is demonstrated that introduced changes in the stereochemistry of the designed ligands increase acidity considerably relative to Al and Sc complexes with analogous monodentate ligands. The high stability of fluoride complexes of these species makes them ideal candidates to be used as weakly coordinating anions in combination with highly reactive cations instead of conventional Lewis acid-fluoride complexes. Further, the interaction of all designed molecules with methane is investigated. All studied acids form stable pentavalent-carbon complexes with methane. In addition, interactions of the strongest acid of this family with very weak bases, namely, H2, N2, carbon oxides, and noble gases were investigated; it is demonstrated that this compound can form considerably stable complexes with the aforementioned molecules. To the best of our knowledge, carbonyl and nitrogen complexes of this species are the first hypothetical four-coordinated carbonyl and nitrogen complexes of aluminum. The nature of bonding in these systems is studied in detail by various bonding analysis approaches. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. The influence of saturated fatty acids on complex index and in vitro digestibility of rice starch.

    Science.gov (United States)

    Soong, Yean Yean; Goh, Hui Jen; Henry, C Jeya K

    2013-08-01

    In Asia, rice and rice products are the main sources of carbohydrate contributing to both dietary energy and glycaemic load. It is known that complexation of starch with lipids could potentially reduce the availability of starch to enzymatic degradation. The aim of this study was to investigate the effect of capric, lauric, myristic, palmitic and stearic acids, ranging from 0 to 2 mmol/g starch, on complexing index and in vitro digestibility of gelatinized rice starch. The results revealed that the ability of rice starch to complex with saturated fatty acids increased with increasing concentration; but reduced with increasing lipid chain length. The complexation of rice starch with capric, lauric, myristic and stearic acids did not reduce the in vitro starch digestibility, except rice starch-palmitic acid complexes.

  16. Complexation of U(VI) with 1-Hydroxyethane-1,1-diphosphonicAcid (HEDPA) in Acidic to Basic Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Reed, W A; Rao, L; Zanonato, P; Garnov, A; Powell, B A; Nash, K L

    2007-01-24

    Complexation of U(VI) with 1-hydroxyethane-1,1-diphosphonic acid (HEDPA) in acidic to basic solutions has been studied with multiple techniques. A number of 1:1 (UO{sub 2}H{sub 3}L), 1:2 (UO{sub 2}H{sub j}L{sub 2} where j = 4, 3, 2, 1, 0 and -1) and 2:2 ((UO{sub 2}){sub 2}H{sub j}L{sub 2} where j = 1, 0 and -1) complexes form, but the 1:2 complexes are the major species in a wide pH range. Thermodynamic parameters (formation constants, enthalpy and entropy of complexation) were determined by potentiometry and calorimetry. Data indicate that the complexation of U(VI) with HEDPA is exothermic, favored by the enthalpy of complexation. This is in contrast to the complexation of U(VI) with dicarboxylic acids in which the enthalpy term usually is unfavorable. Results from electrospray ionization mass spectrometry (ESI-MS) and {sup 31}P NMR have confirmed the presence of 1:1, 1:2 and 2:2 U(VI)-HEDPA complexes.

  17. [Thermodynamic characteristics of nucleic acid complexes with silver ions].

    Science.gov (United States)

    Minasian, K A; Poletaev, A I; Borob'ev, A F

    1981-01-01

    By means of mixing reaction calorimetry the enthalpy of the complexes formation between Ag+ ions and DNA and dsRNA was measured. It was shown that Ag+ ions are able to form two types of complexes (I and II) with dsRNA. Using the method of the competitive reaction with chloride ions the stability constants of complex formation were obtained for dsRNA-Ag+ complexes for different temperatures. These measurements gave the delta H and delta S values for both complexes: delta HI = -74,9 +/- 7,1 kjouls/mol, delta SI = -100.0 +/- 25.0 jouls/mol deg; delta HII = -39,8 +/- 4,2 kjouls/mol, delta SII = +2 +/- 14 jouls/mol deg. The calorimetric results of delta H determination are the same within the limits of experimental errors. The enthalpy term of dsRNA-Ag+ complexes proved to bring the main contribution into the free energy of complex formation.

  18. Improvement on stability of square planar rhodium (Ⅰ) complexes for carbonylation of methanol to acetic acid

    Institute of Scientific and Technical Information of China (English)

    蒋华; 潘平来; 袁国卿; 陈新滋

    1999-01-01

    A series of square planar cis-dicarbonyl polymer coordinated rhodium complexes with uncoordinated donors near the central rhodium atoms for carbonylation of methanol to acetic acid are reported. Data of IR, XPS and thermal analysis show that these complexes are very stable. The intramolecular substitution reaction is proposed for their high stability. These complexes show excellent catalytic activity, selectivity and less erosion to the equipment for the methanol carbonylation to acetic acid. The distillation process may be used instead of flash vaporization in the manufacture of acetic acid, which reduces the investment on the equipment.

  19. Lipid complex effect on fatty acid profile and chemical composition of cow milk and cheese.

    Science.gov (United States)

    Bodkowski, R; Czyż, K; Kupczyński, R; Patkowska-Sokoła, B; Nowakowski, P; Wiliczkiewicz, A

    2016-01-01

    The effect of administration of lipid complex (LC) on cow milk and cheese characteristics was studied. Lipid complex was elaborated based on grapeseed oil with synthesized conjugated linoleic acid (CLA) and Atlantic mackerel oil enriched in n-3 fatty acids. The 4-wk experiment was conducted on 30 Polish Holstein Friesian cows. The experimental group cow diet was supplemented with 400 g/d of LC (containing 38% CLA, and eicosapentaenoic acid + docosahexaenoic acid in a relative amount of 36.5%) on a humic-mineral carrier. The chemical composition and fatty acid profile of milk and rennet cheese from raw fresh milk were analyzed. Lipid complex supplementation of the total mixed ration had no effect on milk yield and milk composition, except fat content, which decreased from 4.6 to 4.1%, a 10.9% decrease. Milk from cows treated with LC had greater relative amounts of unsaturated fatty acids, particularly polyunsaturated fatty acids, and lesser relative amounts of saturated fatty acids. Lipid complex addition changed milk fat fatty acid profile: C18:2 cis-9,trans-11 and trans-10,cis-12 isomer (CLA) contents increased by 278 and 233%, respectively, as did eicosapentaenoic acid (C20:5) and docosahexaenoic acid (C22:6) contents. Milk fat fatty acid profile changes were correlated with the modifications in rennet cheese fatty acid profile. Lipid complex supplementation of dairy cows produced considerable changes in the biological value of milk and cheese fat. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  20. Polymers with complexing properties. Simple poly(amino acids)

    Science.gov (United States)

    Roque, J. M.

    1978-01-01

    The free amino (0.3 equiv/residue) and carboxyl (0.5 equiv/residue) groups of thermal polylysine increased dramatically on treatment with distilled water. The total hydrolysis of such a polymer was abnormal in that only about 50% of the expected amino acids were recovered. Poly (lysine-co-alanine-co-glycine) under usual conditions hydrolyzed completely in 8 hours; whereas, when it was pretreated with diazomethane, a normal period of 24 hours was required to give (nearly) the same amounts of each free amino acid as compared with those obtained from the untreated polymer. The amino groups of the basic thermal poly(amino acids) were sterically hindered. The existence of nitrogen atoms linking two or three chains and reactive groups (anhydride, imine) were proposed.

  1. Synthesis of zincosilicate mordenite using citric acid as complexing agent

    Institute of Scientific and Technical Information of China (English)

    MeiDong; JianjuoWang; YuhanSun

    2001-01-01

    The zincosilicate analog of zeolite mordenite was hydrothermally synthesized in the presence of citric acid and characterized with several spectroscopic techniques.The zeolite thus prepared had a higher crystallinity and Zn concentration in the framework compared with the one obtained in the absence of citric acid.XRD and FTIR provided evidence for the incorporation of Zn in the framework.Results of XAFS indicated a tetrahedral structure of Zn in the lattice framework with a Zn-O distancd of 0.1938nm.It is speculated that the citric acid might decrease the concentration of Zn2 in the synthesis mixture,there by preventing the unfavorable-formation of oxide or hydroxide species.2001 Elsevier Science B.V.All rights reserved.

  2. CEC mechanism in electrochemical oxidation of nitrocatechol-boric acid complexes

    Energy Technology Data Exchange (ETDEWEB)

    Rafiee, Mohammad, E-mail: rafiee@iasbs.ac.ir [Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan (Iran, Islamic Republic of); Nematollahi, Davood; Salehzadeh, Hamid [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of)

    2011-11-30

    Graphical abstract: Display Omitted Highlights: > Nitrochetechol and its anionic form undergo complex reaction with boric acid. > The electron transfer of complex is coupled with both proceeding and following chemical reactions. > Electrochemical behavior of complex is resolved by diagnostic criteria and digital simulation. - Abstract: The electrochemical behavior of nitrocatechols-boric acid complexes in aqueous solution has been studied using cyclic voltammetry. The results indicate that nitrocatechol-boric acid complex derivatives are involved in the CEC mechanism. In this work, the impact of empirical parameters on the shape of the voltammograms is examined based on a CEC mechanism. In addition, homogeneous rate constants of both the preceding and the following reactions were estimated by comparing the experimental cyclic voltammograms with the digitally simulated results. The calculated dissociation constants for the complexes (K{sub d}) and for ring cleavage of nitroquinone (k{sub f2}) were found to vary in the following order: 4-nitrocatechol > 3-methylnitrocatechol > 3-metoxynitrocatechol.

  3. Complexity analysis of the glutamic acid ion-exchanged wastewater

    Institute of Scientific and Technical Information of China (English)

    林艳; 王瑞明; 徐国华; 王腾飞; 井瑞洁

    2008-01-01

    In this paper,the glutamic acid ion-exchanged wastewater has been studied.Kjeldahl determination method,Fehling reagent.muffle furnace method.and so on were used.It can be sure that the wastewater's COD is 50250 mg/L.and total solids is 13.76%.it contains:glutamic acid 0.3%:total reducing sugar 0.414%;fat 0.4274%;ammonium sulphate 10.0758%;microbial protein 0.8045%;ash 0.27%:others 1.4683%.

  4. Competition of hydrogen bonds and halogen bonds in complexes of hypohalous acids with nitrogenated bases.

    Science.gov (United States)

    Alkorta, Ibon; Blanco, Fernando; Solimannejad, Mohammad; Elguero, Jose

    2008-10-30

    A theoretical study of the complexes formed by hypohalous acids (HOX, X = F, Cl, Br, I, and At) with three nitrogenated bases (NH 3, N 2, and NCH) has been carried out by means of ab initio methods, up to MP2/aug-cc-pVTZ computational method. In general, two minima complexes are found, one with an OH...N hydrogen bond and the other one with a X...N halogen bond. While the first one is more stable for the smallest halogen derivatives, the two complexes present similar stabilities for the iodine case and the halogen-bonded structure is the most stable one for the hypoastatous acid complexes.

  5. Evaluation of structural and functional properties of chitosan-chlorogenic acid complexes.

    Science.gov (United States)

    Wei, Zihao; Gao, Yanxiang

    2016-05-01

    The objectives of the present study were to first synthesize chitosan-chlorogenic acid (CA) covalent complex and then compare structural and functional properties between chitosan-CA covalent complex and physical complex. First, chitosan-CA covalent complex was synthesized and its total phenolic content was as high as 276.5 ± 6.2 mg/g. Then structural and functional properties of chitosan-CA covalent and physical complexes were analyzed. The covalent reaction induced formation of both amide and ester bonds in chitosan. Data of X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated that the complexations of CA changed crystallinity and morphology of chitosan, and covalent complexation induced a larger change of physical structure than physical complexation. In terms of functional properties, chitosan-CA covalent complex exhibited better thermal stability than physical complex in terms of antioxidant activity, and the viscosity of chitosan was significantly increased by covalent modification.

  6. Investigation of complex formation processes of hydroxypropylmethylcellulose and polymethacrylic acid in aqueous solutions

    Directory of Open Access Journals (Sweden)

    M. Katayeva

    2012-12-01

    Full Text Available The complex formation process of hydroxypropylcellulose (HPC with polymethacrylic acid (PMA have been studied using methods of turbidimetric and viscosimetric titration. Position of maximum depending on polymer concentration and molecular mass of polysaccharide have different values.

  7. Seven hexamethylenetetramine (HMTA) complexes with mono- and dicarboxylic acids: analysis of packing modes of HMTA complexes in the literature.

    Science.gov (United States)

    Lemmerer, Andreas

    2011-04-01

    The crystal structures of seven hexamethylenetetramine (HMTA) complexes, or co-crystals, with carboxylic acid donor molecules are reported to explain the link between the molecular structure of HMTA and the crystal structure of the co-crystals, i.e. the dimension and shape of their hydrogen-bonded assembly. A comprehensive and detailed literature survey of HMTA complexes (38), be they neutral co-crystals or salts, with molecules containing carboxylic acid and phenol functional groups reveals that in general two N acceptors are used for strong O-H···N interactions. Owing to the relative arrangement of two of the four N atoms, the most common type of assembly features one-dimensional zigzag chains. Weak interactions of the C-H···N type are formed by N atoms not involved in strong interactions. These chains also form the basis of two-dimensional assemblies. These one- and two-dimensional assemblies feature either two or three functional groups. If only one functional group is on the donor molecule, then wing or V-shaped zero-dimensional assemblies are formed, which can be considered to be the building blocks for one- and two-dimensional assemblies. In general, the HMTA molecules form two-dimensional layers which are stabilized by weak hydrogen bonds. Co-crystals with cyclohexylcarboxylic acid (I), 4-fluorobenzoic acid (II), 4-methylbenzoic acid (III) and cinnamic acid (IV) all feature the V-shaped zero-dimensional assemblies. Co-crystals with cis-1,4-cyclohexyldicarboxylic acid (VI) and trans-1,4-cyclohexylcarboxylic acid (VII) feature the zigzag chains and can be structurally derived from co-crystal (I). Co-crystal (V), with 4-nitrobenzoic acid, has solvent water included and features hydrogen bonding to all four N atoms of the HMTA molecule.

  8. Vinylic polymerization of Norbornenecarboxylic Acid Esters by Palladium Complexes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    New thermoplastic norbornene polymers containing ester groups were prepared byvinylic polymerization of norbornene-carboxylic acid esters by Pd(Ⅱ)-based catalysts. Themonomers were obtained by Diels-Alder reaction of cyclopentadiene with acrylic acid esters(methyl and butyl) as mixtures of endo/exo (ratio 40/60)-isomers and were converted topolymers in 60%~70% conversion. The endo-isomer was less reactive than the exo-isomer.To obtain higher molecular weight the more reactive pure exo-isomer was prepared andpolymerized with the Pd (Ⅱ)-catalysts, tetrakis (acetonitrile) Pd (Ⅱ) bis (tetrafluoroborate)and (η3-allyl)Pd(Ⅱ)SbF6, in high conversion. These polymers showed high glass transitiontemperatures, high transparency and good solubility in common solvents.

  9. From Bidentate Gallium Lewis Acids to Supramolecular Complexes.

    Science.gov (United States)

    Horstmann, Jan; Hyseni, Mentor; Mix, Andreas; Neumann, Beate; Stammler, Hans-Georg; Mitzel, Norbert W

    2017-05-22

    Bidentate gallium Lewis acids were prepared by the reaction of diethynyldiphenylsilane with neat trimethyl- or triethylgallium. Bis[(dimethylgallyl)ethynyl]diphenylsilane (1) and diethylgallyl derivative 2 were characterized as Et2 O or pyridine adducts by NMR spectroscopy; 2⋅2Py was isolated. Lewis acids 1 and 2 form host-guest adducts with bidentate nitrogen bases, but defined cyclic 1:1 adducts are only formed between 1 and bases with matching N⋅⋅⋅N distances: 4,4'-dimethyl-3,3'-bipyridinylacetylene (3), bis[(pyridin-3-yl)ethynyl]diphenylsilane (4), and bis[(2-methylpyridin-5-yl)ethynyl]diphenylsilane (5). The structures of adducts 1⋅3, 1⋅4, and 1⋅5 were established by X-ray diffraction experiments. 2⋅2Py reacts with DABCO to afford polymeric (DABCO-2-)n . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Superiority of zinc complex of acetylsalicylic acid to acetylsalicylic acid in preventing postischemic myocardial dysfunction.

    Science.gov (United States)

    Korkmaz, Sevil; Atmanli, Ayhan; Li, Shiliang; Radovits, Tamás; Hegedűs, Peter; Barnucz, Enikő; Hirschberg, Kristóf; Loganathan, Sivakkanan; Yoshikawa, Yutaka; Yasui, Hiroyuki; Karck, Matthias; Szabó, Gábor

    2015-09-01

    The pathophysiology of ischemic myocardial injury involves cellular events, reactive oxygen species, and an inflammatory reaction cascade. The zinc complex of acetylsalicylic acid (Zn(ASA)2) has been found to possess higher anti-inflammatory and lower ulcerogenic activities than acetylsalicylic acid (ASA). Herein, we studied the effects of both ASA and Zn(ASA)2 against acute myocardial ischemia. Rats were pretreated with ASA (75 mg/kg) or Zn(ASA)2 (100 mg/kg) orally for five consecutive days. Isoproterenol (85 mg/kg, subcutaneously [s.c.]) was applied to produce myocardial infarction. After 17-22 h, animals were anesthetized with sodium pentobarbital (60 mg/kg, intraperitoneally [i.p.]) and both electrical and mechanical parameters of cardiac function were evaluated in vivo. Myocardial histological and gene expression analyses were performed. In isoproterenol-treated rats, Zn(ASA)2 treatment normalized significantly impaired left-ventricular contractility index (Emax 2.6 ± 0.7 mmHg/µL vs. 4.6 ± 0.5 mmHg/µL, P < 0.05), increased stroke volume (30 ± 3 µL vs. 50 ± 6 µL, P < 0.05), decreased systemic vascular resistance (7.2 ± 0.7 mmHg/min/mL vs. 4.2 ± 0.5 mmHg/min/mL, P < 0.05) and reduced inflammatory infiltrate into the myocardial tissues. ECG revealed a restoration of elevated ST-segment (0.21 ± 0.03 mV vs. 0.09 ± 0.02 mV, P < 0.05) and prolonged QT-interval (79.2 ± 3.2 ms vs. 69.5 ± 2.5 ms, P < 0.05) by Zn(ASA)2. ASA treatment did not result in an improvement of these parameters. Additionally, Zn(ASA)2 significantly increased the mRNA-expression of superoxide dismutase 1 (+73 ± 15%), glutathione peroxidase 4 (+44 ± 12%), and transforming growth factor (TGF)-β1 (+102 ± 22%). In conclusion, our data demonstrate that oral administration of zinc and ASA in the form of bis(aspirinato)zinc(II) complex is superior to ASA in preventing electrical

  11. Water-free Alkaline Polymer-inorganic Acid Complexes with High Conductivity at Ambient Temperature

    Institute of Scientific and Technical Information of China (English)

    O.V.Chervakov; M.V.Andriianova; V.V.Riabenko; A.V.Markevich; E.M.Shembel; D.Meshri

    2007-01-01

    1 Results Recently increased interest is shown to proton conducting materials based on the alkaline polymer-inorganic acid complexes that is caused by a possibility of their application as the high-temperature electrolyte systems for various electrochemical devices (fuel cells,sensors,lithium power sources etc.).Complexes of inorganic acids with the alkaline polymers (polybenzimidazoles[1],polyvinylpyridines[2]) are characterized by high ionic conductivity at ambient temperatures (up to 10-2 Ω-1·cm-1) a...

  12. Spectroscopic studies on gallic acid and its azo derivatives and their iron(III) complexes.

    Science.gov (United States)

    Masoud, Mamdouh S; Ali, Alaa E; Haggag, Sawsan S; Nasr, Nessma M

    2014-01-01

    Azo gallic derivatives and their iron(III) complexes were synthesized and characterized. The stereochemistry and the mode of bonding of the complexes were achieved based on elemental analysis, UV-Vis and IR. The thermal behaviors of the complexes were studied. The effect of pH on the electronic absorption spectra of gallic acid and its azo derivatives are discussed. Different spectroscopic methods (molar ratio, straight line method, continuous variation, slope ratio and successive method) are applied for determination of stoichiometry and pK values for the complex formation of gallic acid with iron(III) in aqueous media. Iron(III) complexes of gallic acid is formed with different ratio: 1:1, 1:2, 1:3 and 1:4 (M:L).

  13. Zeolite-Encapsulated Copper(II) Amino Acid Complexes: Synthesis, Spectroscopy, and Catalysis

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Verberckmoes, A.A.; Fu, L.; Schoonheydt, R.A.

    1995-01-01

    The spectroscopic properties and catalytic behavior of Cu(AA)n m+ complexes (AA ) amino acid (glycine, lysine, histidine, alanine, serine, proline, tyrosine, phenylalanine, glutamine, glutamic acid, cysteine, tryptophan, leucine, and arginine)) in faujasite-type zeolites have been investigated. Succ

  14. Zeolite-Encapsulated Copper(II) Amino Acid Complexes: Synthesis, Spectroscopy, and Catalysis

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Verberckmoes, A.A.; Fu, L.; Schoonheydt, R.A.

    2001-01-01

    The spectroscopic properties and catalytic behavior of Cu(AA)n m+ complexes (AA ) amino acid (glycine, lysine, histidine, alanine, serine, proline, tyrosine, phenylalanine, glutamine, glutamic acid, cysteine, tryptophan, leucine, and arginine)) in faujasite-type zeolites have been investigated. Succ

  15. Acid-base crystalline complexes and the pK(a) rule

    NARCIS (Netherlands)

    Cruz-Cabeza, A.J.

    2012-01-01

    Differences in the predicted aqueous pKa values (ΔpKa) have been calculated for 6465 crystalline complexes containing ionised and non-ionised acid-base pairs in the Cambridge Structural Database. A linear relationship between ΔpKa and the probability of proton transfer between acid-base pairs has be

  16. Metals complexation with humic acids in surface water of different natural–climatic zones

    OpenAIRE

    Dinu M. I.

    2013-01-01

    Humic acids extracted from different soils. The stability constants of metal humates and acid dissociation constant humic acids were calculated. Forms of metals in natural waters was determined with use account their chemical composition and content and properties of organic matter. We assessed metals speciation in water objects with account for competitive reactions resulting in formation of hydroxide, hydrocarbonate, sulfate, and chloride metal complexes and obtained a competitive series of...

  17. Metals complexation with humic acids in surface water of different natural–climatic zones

    Directory of Open Access Journals (Sweden)

    Dinu M. I.

    2013-04-01

    Full Text Available Humic acids extracted from different soils. The stability constants of metal humates and acid dissociation constant humic acids were calculated. Forms of metals in natural waters was determined with use account their chemical composition and content and properties of organic matter. We assessed metals speciation in water objects with account for competitive reactions resulting in formation of hydroxide, hydrocarbonate, sulfate, and chloride metal complexes and obtained a competitive series of metal activity in natural waters of the zones considered.

  18. Brønsted Acid Catalysis—Structural Preferences and Mobility in Imine/Phosphoric Acid Complexes

    Science.gov (United States)

    2016-01-01

    Despite the huge success of enantioselective Brønsted acid catalysis, experimental data about structures and activation modes of substrate/catalyst complexes in solution are very rare. Here, for the first time, detailed insights into the structures of imine/Brønsted acid catalyst complexes are presented on the basis of NMR data and underpinned by theoretical calculations. The chiral Brønsted acid catalyst R-TRIP (3,3′-bis(2,4,6-triisopropylphenyl)-1,1′-binaphthyl-2,2′-diyl hydrogen phosphate) was investigated together with six aromatic imines. For each investigated system, an E-imine/R-TRIP complex and a Z-imine/R-TRIP complex were observed. Each of these complexes consists of two structures, which are in fast exchange on the NMR time scale; i.e., overall four structures were found. Both identified E-imine/R-TRIP structures feature a strong hydrogen bond but differ in the orientation of the imine relative to the catalyst. The exchange occurs by tilting the imine inside the complex and thereby switching the oxygen that constitutes the hydrogen bond. A similar situation is observed for all investigated Z-imine/R-TRIP complexes. Here, an additional exchange pathway is opened via rotation of the imine. For all investigated imine/R-TRIP complexes, the four core structures are highly preserved. Thus, these core structures are independent of electron density and substituent modulations of the aromatic imines. Overall, this study reveals that the absolute structural space of binary imine/TRIP complexes is large and the variations of the four core structures are small. The high mobility is supposed to promote reactivity, while the preservation of the core structures in conjunction with extensive π–π and CH−π interactions leads to high enantioselectivities and tolerance of different substrates. PMID:27960345

  19. Metal complexes of salicylhydroxamic acid (H2Sha), anthranilic hydroxamic acid and benzohydroxamic acid. Crystal and molecular structure of [Cu(phen)2(Cl)]Cl x H2Sha, a model for a peroxidase-inhibitor complex.

    Science.gov (United States)

    O'Brien, E C; Farkas, E; Gil, M J; Fitzgerald, D; Castineras, A; Nolan, K B

    2000-04-01

    Stability constants of iron(III), copper(II), nickel(II) and zinc(II) complexes of salicylhydroxamic acid (H2Sha), anthranilic hydroxamic acid (HAha) and benzohydroxamic acid (HBha) have been determined at 25.0 degrees C, I=0.2 mol dm(-3) KCl in aqueous solution. The complex stability order, iron(III) > copper(II) > nickel(II) approximately = zinc(II) was observed whilst complexes of H2Sha were found to be more stable than those of the other two ligands. In the preparation of ternary metal ion complexes of these ligands and 1,10-phenanthroline (phen) the crystalline complex [Cu(phen)2(Cl)]Cl x H2Sha was obtained and its crystal structure determined. This complex is a model for hydroxamate-peroxidase inhibitor interactions.

  20. Synthesis and Characterization of Lanthanum Complexes with Amino Acid Schiff Base

    Institute of Scientific and Technical Information of China (English)

    张秀英; 张有娟; 杨林

    2001-01-01

    Six new complexes of lanthanum with amino acid Schiff base ligands, A-F, were prepared in methanol-aqueous solution. The composition and properties of the title complexes were characterized by elemental analysis, molar conductance, infrared, electronic spectra, 1H NMR, thermogravimetric and differential thermal analysis.

  1. Synthesis, structure and spectroscopic studies of europium complex with S(+)-mandelic acid

    Institute of Scientific and Technical Information of China (English)

    M. Babij; A. Mondry

    2011-01-01

    The Eu3+ complexes with S(+)-mandelic acid were synthesized in the form of powders by mixing aqueous solutions of EuCl3,S(+)-mandelic acid and NaOH in different molar ratios.The powders were characterized by elemental analysis,X-ray powder diffraction (XRPD) method,Fourier transform infrared (FTIR) and Raman spectroscopy,UV-vis reflectance and luminescence spectra as well as luminescence lifetime measurements.It was found that all studied powders of Eu3+ complexes with S(+)-mandelic acid were isostructural and crystalline and formed compounds with the formula Eu(Man)3(H2O)2.

  2. Oxidation of aromatic alcohols on zeolite-encapsulated copper amino acid complexes

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, S.; Teixeira Florencio, J.M. [Kaiserslautern Univ. (Germany). Dept. of Chemistry, Chemical Technology

    1998-12-31

    Copper complexes of the amino acids histidine, arginine and lysine have been introduced into the supercages of zeolite Y and, for the first time, into the large intracrystalline cavities of zeolites EMT and MCM-22. The resulting host/guest compounds are characterized by X-ray powder diffraction, UV/VIS-spectroscopy in the diffuse reflectance mode and by catalytic tests in the liquid-phase oxidation of aromatic alcohols (viz. benzyl alcohol, 2- and 3-methylbenzyl alcohol and 2,5-dimethylbenzyl alcohol) with tertiary-butylhydroperoxide as oxidant. It was observed that intracrystalline copper-amino acid complexes possess remarkable catalytic activity, yielding the corresponding aromatic aldehydes and acids. (orig.)

  3. Kinetic study of the complexation of gallic acid with Fe(II)

    Science.gov (United States)

    Lu, Li-li; Li, Ying-hua; Lu, Xiu-yang

    2009-10-01

    Kinetic study on the complexation of gallic acid with ferrous sulfate was performed using UV-Vis absorption spectroscopy. Under the experimental conditions, the stoichiometric composition of the formed complex is 1:1. The complexation reaction was found to be a second-order one. The influences of temperature, ionic strength and solvents on the complexation reaction were investigated. According to the Arrhenius equation, the apparent activation energy of the complexation reaction was evaluated to be 71.64 kJ × mol -1. A three-step reaction mechanism was proposed, which can well explain the kinetic results obtained.

  4. Intraparticulate Metal Speciation Analysis of Soft Complexing Nanoparticles. The Intrinsic Chemical Heterogeneity of Metal-Humic Acid Complexes

    DEFF Research Database (Denmark)

    Town, R. M.; van Leeuwen, Herman P.

    2016-01-01

    ion condensation potential for higher valency counterions within the intraparticulate double layer zone of the soft NP. The approach offers new insights into the intrinsic heterogeneity of the HA. complexes, as revealed by the intraparticulate speciation as a function of the true degree of inner......The counterion condensation-Dorman (CCD) model for the electrostatic features of soft, charged nanopartides (NPs) is applied to the determination of the intrinsic stability constants, kit, for inner-sphere Cd(II) and Cu(II) complexes with humic acid NPs. The novel CCD model accounts for the strong......-sphere complexation, theta(M). The ensuing intrinsic heterogeneity parameters, Gamma, for CdHA and CuHA complexes are in very good agreement with those obtained from dynamic electrochemical stripping chronopotentiometric measurements. The overall intraparticulate metal ion speciation is found to depend on theta...

  5. Hydrolytic activity of -alkoxide/acetato-bridged binuclear Cu(II) complexes towards carboxylic acid ester

    Indian Academy of Sciences (India)

    Weidong Jiang; Bin Xu; Zhen Xiang; Shengtian Huang; Fuan Liu; Ying Wang

    2013-09-01

    Two -alkoxide/acetate-bridged small molecule binuclear copper(II) complexes were synthesized, and used to promote the hydrolysis of a classic carboxylic acid ester, -nitrophenyl picolinate (PNPP). Both binuclear complexes exhibited good hydrolytic reactivity, giving rise to . 15547- and 17462-fold acceleration over background value for PNPP hydrolysis at neutral conditions, respectively. For comparing, activities of the other two mononuclear analogues were evaluated, revealing that binuclear complexes show approximately 150- and 171-fold kinetic advantage over their mononuclear analogues.

  6. Spectra, energy levels, and energy transition of lanthanide complexes with cinnamic acid and its derivatives.

    Science.gov (United States)

    Zhou, Kaining; Feng, Zhongshan; Shen, Jun; Wu, Bing; Luo, Xiaobing; Jiang, Sha; Li, Li; Zhou, Xianju

    2016-04-05

    High resolution spectra and luminescent lifetimes of 6 europium(III)-cinnamic acid complex {[Eu2L6(DMF)(H2O)]·nDMF·H2O}m (L=cinnamic acid I, 4-methyl-cinnamic acid II, 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV, 4-hydroxy-cinnamic acid V, 4-nitro-cinnamic acid VI; DMF=N, N-dimethylformamide, C3H7NO) were recorded from 8 K to room temperature. The energy levels of Eu(3+) in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu(3+) ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p-π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I. While the other complexes show poorer matching because the gap of (5)D0 and triplet state contracts.

  7. Zinc complexes as fluorescent chemosensors for nucleic acids: new perspectives for a "boring" element.

    Science.gov (United States)

    Terenzi, Alessio; Lauria, Antonino; Almerico, Anna Maria; Barone, Giampaolo

    2015-02-28

    Zinc(II) complexes are effective and selective nucleic acid-binders and strongly fluorescent molecules in the low energy range, from the visible to the near infrared. These two properties have often been exploited to quantitatively detect nucleic acids in biological samples, in both in vitro and in vivo models. In particular, the fluorescent emission of several zinc(II) complexes is drastically enhanced or quenched by the binding to nucleic acids and/or upon visible light exposure, in a different fashion in bulk solution and when bound to DNA. The twofold objective of this perspective is (1) to review recent utilisations of zinc(II) complexes as selective fluorescent probes for nucleic acids and (2) to highlight their novel potential applications as diagnostic tools based on their photophysical properties.

  8. The Cp-Ftmw Spectroscopy and Assignment of the - and Dihydrate Complexes of Perfluoropropionic Acid

    Science.gov (United States)

    Grubbs, G. S., II; Obenchain, Daniel A.; Frank, Derek S.; Novick, Stewart E.; Cooke, S. A.; Serrato, Agapito, III; Lin, Wei

    2015-06-01

    While searching for the chirped pulse spectra of allyl phenyl ether, the authors used current rotational spectroscopic fitting tools to assign multiple sets of spectra of unknown origin. Previous chirped pulse experiments searching for hydrate complexes of perfluoropropionic acid had not been successful but, through theoretical agreement, it was determined that at least one of the sets of unknown spectra observed belonged to the perfluoropropionic acid-water complex. Further determination showed that the dihydrate had also been observed. The determination process and spectral assignment will be discussed. Structural determinations of the complexes will also be discussed.

  9. Leaching of complex sulphide concentrate in acidic cupric chloride solutions

    Institute of Scientific and Technical Information of China (English)

    M. TCHOUMOU; M. ROYNETTE

    2007-01-01

    The chemical analysis of a complex sulphide concentrate by emission spectrometry and X-ray diffraction shows that it contains essentially copper, lead, zinc and iron in the form of chalcopyrite, sphalerite and galena. A small amount of pyrite is also present in the ore but does not be detected with X-ray diffraction. The cupric chloride leaching of the sulphide concentrate at various durations and solid/liquid ratios at 100 ℃ shows that the rate of dissolution of the ore is the fastest in the first several hours, and after 12 h it does not evolve significantly. If oxygen is excluded from the aqueous cupric chloride solution during the leaching experiment at 100 ℃, the pyrite in the ore will not be leached. The determination of principal dissolved metals in the leaching liquor by flame atomic absorption spectrometry, and the chemical analysis of solid residues by emission spectrometry and X-ray diffraction allow to conclude that the rate of dissolution of the minerals contained in the complex sulphide concentrate are in the order of galena>sphalerite>chalcopyrite.

  10. Cytotoxicity of copper(II) complexes of N-salicylidene-L-glutamate: modulation by ascorbic acid.

    Science.gov (United States)

    Paulikova, H; Kadlecikova, E; Suchanova, M; Valkova, Z; Rauko, P; Hudecova, D; Valent, A

    2008-01-01

    Cytotoxic/cytostatic activity of N-salicylidene-L-glutamato diaqua copper(II) complex (CuC) against mice leukemia cells L1210 has been estimated and their bioactivity was enhanced by addition of ascorbic acid. The Cu-complex with isoquinoline ligand (IQ-CuC) had stronger cytostatic effect (IC50 =15.6 microM) than parental complex (CuC) and its cytotoxicity several times increased in the presence of 0.1 mM ascorbic acid (IC50 =1.0 microM). The cytotoxicity has been caused by oxidative stress, enhanced creation of TBARS has been confirmed, and formation of 2',7'-dichlorofluorescein from 2',7'- dichlorodihydrofluorescein has been observed, also. Some hallmarks of apoptotic/necrotic death of L1210 cells have been observed by fluorescent microscopy after dyeing of cell with propidium iodide and Hoechst 33342. In addition, it was confirmed that both complexes in the presence of ascorbic acid cleavaged of pDNA. Although these copper complexes were initially prepared as substances with antioxidant properties we have showed that combined treatment of L1210 cells with IQCuC and ascorbic acid induced strong oxidative stress and death of cells. Our results confirmed that physiological concentration of ascorbic acid increases the cytostatic/cytotoxic efficiency of N-salicylidene-L-glutamato diaqua copper(II) complexes.

  11. Adsorption and mobility of Cr(III)-organic acid complexes in soils.

    Science.gov (United States)

    Cao, Xinhua; Guo, Jing; Mao, Jingdong; Lan, Yeqing

    2011-09-15

    The soluble Cr(III) is likely to be complexed with organic ligands in ligand-rich soil. Cr(VI) chemical reduction by organic acids and bioreduction by microorganisms can produce soluble Cr(III)-organic acids complexes. Thus, it is of great significance to investigate the absorption and mobility of Cr(III)-organic acid complexes in soils. In this study, Cr(III)-EDTA and Cr(III)-cit were prepared and purified, and then were examined for adsorption and mobility. The results demonstrated that Cr(III) was strongly bound to soil, while Cr(III)-organic acid complexes had no or slight interaction with soils since Cr(III)-EDTA and Cr(III)-cit complexes mainly existed as the forms of [Cr(III)-EDTA](-) and [Cr(III)-cit], respectively, under the tested conditions with initial pH 4.0-9.0. The adsorption of Cr(III) increased but that of Cr(III)-organic acid complexes decreased with the content of soil organic matter. Compared with Cr(III)-EDTA, the mobility of Cr(III)-cit in soil columns was reduced, due to the specific adsorption between soils and Cr(III)-cit which contained one free hydroxyl group. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Influence of phytic acid and its metal complexes on the activity of pectin degrading polygalacturonase.

    Science.gov (United States)

    Asghar, Uzma; Rehman, Haneef Ur; Qader, Shah Ali Ul; Maqsood, Zahida Tasneem

    2013-06-05

    Polygalacturonase is one of the important requirements of different microorganism to cause pathogenicity and spoilage of fruits and vegetables that involved in degradation of pectin during plant tissue infections. In current study, 20 mM phytic acid inhibited 70% activity of polygalacturonase. The effect of different concentration of metal ions such as Cu(+2), Al(+3) and V(+4) were studied separately and it was found that the 20 mM of these metal ions inhibited 37.2%, 79%, and 53% activity of polygalacturonase, respectively. Finally, the complexes of phytic acid and these metals ions were prepared and 1:1 ratio of phytic acid and metal ions complexes showed maximum inhibitory activity of enzyme as compared to complexes having 1:2 and 1:3 ratio except phytate-copper complexes which showed no inhibitory effect on the activity of polygalacturonase.

  13. Metal complexation inhibits the effect of oxalic acid in aerosols as cloud condensation nuclei (CCN

    Directory of Open Access Journals (Sweden)

    T. Furukawa

    2010-11-01

    Full Text Available Atmospheric aerosols have both a direct and an indirect cooling effect that influences the radiative balance at the Earth's surface. It has been estimated that the degree of cooling is large enough to cancel the warming effect of carbon dioxide. Among the cooling factors, secondary organic aerosols (SOA play a key role in the solar radiation balance in the troposphere as SOA can act as cloud condensation nuclei (CCN and extend the lifespan of clouds because of their high hygroscopic and water soluble nature. Oxalic acid is one of the major components of SOA, and is produced via several formation pathways in the atmosphere. However, it is not certain whether oxalic acid exists as free oxalic acid or as metal oxalate complexes in aerosols, although there is a marked difference in their solubility in water and their hygroscopicity. We employed X-ray absorption fine structure spectroscopy to characterize the calcium (Ca and zinc (Zn in aerosols collected at Tsukuba in Japan with fractionation based on particle size using an impactor aerosol sampler. It was shown that 10–60% and 20–100% of the total Ca and Zn in the finer particles (<2.1 μm were present as Ca and Zn oxalate complexes, respectively. Oxalic acid can act as CCN because of its hygroscopic properties, while metal complexes are not hygroscopic, and so cannot be CCN. Based on the concentration of noncomplexed and metal-complexed oxalate species, we found that most of the oxalic acid is present as metal oxalate complexes in the aerosols, suggesting that oxalic acid does not act as CCN in the atmosphere. Similar results are expected for other dicarboxylic acids, such as malonic and succinic acids. Thus, it is possible that the cooling effect of organic aerosols assumed in various climate modeling studies is overestimated because of the lack of information on metal oxalate complexes in aerosols.

  14. Synthesis, spectral studies and biological evaluation of 2-aminonicotinic acid metal complexes

    Science.gov (United States)

    Nawaz, Muhammad; Abbasi, Muhammad Waseem; Hisaindee, Soleiman; Zaki, Muhammad Javed; Abbas, Hira Fatima; Mengting, Hu; Ahmed, M. Arif

    2016-05-01

    We synthesized 2-aminonicotinic acid (2-ANA) complexes with metals such as Co(II), Fe(III), Ni(II), Mn(II), Zn(II), Ag(I),Cr(III), Cd(II) and Cu(II) in aqueous media. The complexes were characterized and elucidated using FT-IR, UV-Vis, a fluorescence spectrophotometer and thermo gravimetric analysis (TGA). TGA data showed that the stoichiometry of complexes was 1:2 metal/ligand except for Ag(I) and Mn(II) where the ratio was 1:1. The metal complexes showed varied antibacterial, fungicidal and nematicidal activities. The silver and zinc complexes showed highest activity against Bacillus subtilis and Bacillus licheniformis respectively. Fusarium oxysporum was highly susceptible to nickel and copper complexes whereas Macrophomina phaseolina was completely inert to the complexes. The silver and cadmium complexes were effective against the root-knot nematode Meloidogyne javanica.

  15. Comparison of complexation properties of humic acids and simple organic ligands

    Directory of Open Access Journals (Sweden)

    Martina Klucakova*

    2010-12-01

    Full Text Available Simple organic compounds as citric acid, phthalic acid, salicylicacid, EDTA, hydroquinone and pyrocatechol were used as structural models of active sites of humic acids. Combination of high resolution ultrasound spectrometry with potentiometry,conductometry and UV/VIS spectrometry were utilized forcomplexation of copper (II ions by humic acids and modelcompounds. Changes in the slope of measured quantities were used to find the saturation of binding. Ultrasound spectrometry showed follow changes of hydration of interacting species. The differences observed for individual model compounds show that there are active centres not only with various strength and stability of formed complexes but also with their various rigidity and ability of conformational changes.

  16. Electrospun Polymer Nanofibers Reinforced by Tannic Acid/Fe+++ Complexes

    Directory of Open Access Journals (Sweden)

    Weiqiao Yang

    2016-09-01

    Full Text Available We report the successful preparation of reinforced electrospun nanofibers and fibrous mats of polyvinyl alcohol (PVA via a simple and inexpensive method using stable tannic acid (TA and ferric ion (Fe+++ assemblies formed by solution mixing and pH adjustment. Changes in solution pH change the number of TA galloyl groups attached to the Fe+++ from one (pH < 2 to two (3 < pH < 6 to three (pH < 7.4 and affect the interactions between PVA and TA. At pH ~ 5.5, the morphology and fiber diameter size (FDS examined by SEM are determinant for the mechanical properties of the fibrous mats and depend on the PVA content. At an optimal 8 wt % concentration, PVA becomes fully entangled and forms uniform nanofibers with smaller FDS (p < 0.05 and improved mechanical properties when compared to mats of PVA alone and of PVA with TA (p < 0.05. Changes in solution pH lead to beads formation, more irregular FDS and poorer mechanical properties (p < 0.05. The Fe+++ inclusion does not alter the oxidation activity of TA (p > 0.05 suggesting the potential of TA-Fe+++ assemblies to reinforce polymer nanofibers with high functionality for use in diverse applications including food, biomedical and pharmaceutical.

  17. Antibacterial, Prooxidative and Genotoxic Activities of Gallic Acid and its Copper and Iron Complexes against Escherichia coli

    OpenAIRE

    Jonathan M. Barcelo; MILDIAMOND GUIEB; ANDERSON VENTURA; ARYZA NACINO; HERMINIA PINASEN; LEAH VIERNES; TRISHIA YODONG; BIANCA LOU ESTRADA; DANIEL VALDEZ; THRESHA BINWAG

    2014-01-01

    In this study, gallic acid and its complexes with aluminum and iron were investigated for their antibacterial, pro-oxidative, and genotoxic properties at alkaline pH. At 4.0μmol/mL, gallic acid displayed bacteriostatic property while aluminum-gallic acid and iron-gallic acid complexes showed bactericidal property against Escherichia coli ATCC 25922. A higher antibacterial activity was observed in the turbidimetric assay compared to the well-diffusion assay. The metal complexes of ...

  18. Amino acid detection using fluoroquinolone–Cu{sup 2+} complex as a switch-on fluorescent probe by competitive complexation without derivatization

    Energy Technology Data Exchange (ETDEWEB)

    Farokhcheh, Alireza; Alizadeh, Naader, E-mail: alizaden@modares.ac.ir

    2014-01-15

    In this work, we describe the use of fluoroquinolone–Cu{sup 2+} complex as a competitive switch-on fluorescence probe for amino acid determination without derivatization. The fluorescence intensity of this probe, which has been reduced due to effective quenching by Cu{sup 2+} ion, increases drastically by an addition of amino acid (glycine, phenylalanine, sarcosine, aspargine, alanine, proline, arginine, aspartic acid, glutamic acid, lysine, leucine and isoleucine). The overall stability constants of Cu{sup 2+} ion complexes with amino acids were determined by fluorometric titration of fluoroquinolone-Cu{sup 2+} complex with the amino acid solution. Furthermore, the probe shows high calibration sensitivity toward aspartic acid. The fluorescence signal depends linearly on the amino acid concentration within the range of concentration from 1.2×10{sup −7} to 1.1×10{sup −5} mol L{sup −1} for aspartic acid. The detection limit was found 2.7×10{sup −8} mol L{sup −1} with the relative standard deviation (RSD%) about 2.1% (five replicate). -- Highlights: • Amino acids are detected by using fluoroquinolone–Cu{sup 2+} complex as fluorescent probe. • Amino acids were detected based on a competitive complexation reaction. • Probe has been able to recognize amino acids through switch-on fluorescence behavior. • Ultra-trace level of aspartic and glutamic acid is determined without derivatization.

  19. Phosphorescent emissions of phosphine copper(I) complexes bearing 8-hydroxyquinoline carboxylic acid analogue ligands

    Energy Technology Data Exchange (ETDEWEB)

    Małecki, Jan G., E-mail: gmalecki@us.edu.pl [Department of Crystallography, Institute of Chemistry, University of Silesia, Szkolna 9 street, 40-006 Katowice (Poland); Łakomska, Iwona, E-mail: iwolak@chem.umk.pl [Department of Chemistry, Nicolaus Copernicus University, Toruń (Poland); Maroń, Anna [Department of Crystallography, Institute of Chemistry, University of Silesia, Szkolna 9 street, 40-006 Katowice (Poland); Szala, Marcin [Institute of Chemistry, University of Silesia, ul. Szkolna 9, 40-006 Katowice (Poland); Fandzloch, Marzena [Department of Chemistry, Nicolaus Copernicus University, Toruń (Poland); Nycz, Jacek E., E-mail: jacek.nycz@us.edu.pl [Institute of Chemistry, University of Silesia, ul. Szkolna 9, 40-006 Katowice (Poland)

    2015-05-15

    The pseudotetrahedral complexes of [Cu(PPh{sub 3}){sub 2}(L)], where L=8-hydroxy-2-methylquinoline-7-carboxylic acid (1), 8-hydroxy-2,5-dimethylquinoline-7-carboxylic acid (2) or 5-chloro-8-hydroxy-2-methylquinoline-7-carboxylic acid (3) have been synthesized and structurally characterized by X-ray crystallography. Their properties have been examined through combinations of IR, NMR, electronic absorption spectroscopy and cyclic voltammetry. The complexes exhibit extraordinary photophysical properties. Complex (1) in solid state exhibits an emission quantum yield of 4.67% and an excited life time of 1.88 ms (frozen DCM solution up to 6.7 ms). When dissolved in a coordinating solvent (acetonitrile) the charge transfer emission was quenched on a microsecond scale. - Highlights: • Synthesis of copper(I) complexes with 8-hydroxyquinoline carboxylic acid ligands. • Very long lived phosphorescent copper(I) complexes. • [Cu(PPh{sub 3}){sub 2}(L)] where L=8-hydroxy-2-methylquinoline-7-carboxylic acid luminesce in the solid state exhibits extremely long lifetime on millisecond scale (1.9 ms). • In frozen MeOH:EtOH solution lifetime increases to 7 ms. • Quantum efficiency equal to 4.7%.

  20. Complexation of Nickel Ions by Boric Acid or (Poly)borates.

    Science.gov (United States)

    Graff, Anais; Barrez, Etienne; Baranek, Philippe; Bachet, Martin; Bénézeth, Pascale

    2017-01-01

    An experiment based on electrochemical reactions and pH monitoring was performed in which nickel ions were gradually formed by oxidation of a nickel metal electrode in a solution of boric acid. Based on the experimental results and aqueous speciation modeling, the evolution of pH showed the existence of significant nickel-boron complexation. A triborate nickel complex was postulated at high boric acid concentrations when polyborates are present, and the equilibrium constants were determined at 25, 50 and 70 °C. The calculated enthalpy and entropy at 25 °C for the formation of the complex from boric acid and Ni(2+) ions are respectively equal to (65.6 ± 3.1) kJ·mol(-1) and (0.5 ± 11.1) J·K(-1)·mol(-1). The results of this study suggest that complexation of nickel ions by borates can significantly enhance the solubility of nickel metal and nickel oxide depending on the concentration of boric acid and pH. First principles calculations were investigated and tend to show that the complex is thermodynamically stable and the nickel cation in solution should interact more strongly with the [Formula: see text] than with boric acid.

  1. A complex of equine lysozyme and oleic acid with bactericidal activity against Streptococcus pneumoniae.

    Directory of Open Access Journals (Sweden)

    Emily A Clementi

    Full Text Available HAMLET and ELOA are complexes consisting of oleic acid and two homologous, yet functionally different, proteins with cytotoxic activities against mammalian cells, with HAMLET showing higher tumor cells specificity, possibly due to the difference in propensity for oleic acid binding, as HAMLET binds 5-8 oleic acid molecules per protein molecule and ELOA binds 11-48 oleic acids. HAMLET has been shown to possess bactericidal activity against a number of bacterial species, particularly those with a respiratory tropism, with Streptococcus pneumoniae displaying the greatest degree of sensitivity. We show here that ELOA also displays bactericidal activity against pneumococci, which at lower concentrations shows mechanistic similarities to HAMLET's bactericidal activity. ELOA binds to S. pneumoniae and causes perturbations of the plasma membrane, including depolarization and subsequent rupture, and activates an influx of calcium into the cells. Selective inhibition of calcium channels and sodium/calcium exchange activity significantly diminished ELOA's bactericidal activity, similar to what we have observed with HAMLET. Finally, ELOA-induced death was also accompanied by DNA fragmentation into high molecular weight fragments - an apoptosis-like morphological phenotype that is seen during HAMLET-induced death. Thus, in contrast to different mechanisms of eukaryote cell death induced by ELOA and HAMLET, these complexes are characterized by rather similar activities towards bacteria. Although the majority of these events could be mimicked using oleic acid alone, the concentrations of oleic acid required were significantly higher than those present in the ELOA complex, and for some assays, the results were not identical between oleic acid alone and the ELOA complex. This indicates that the lipid, as a common denominator in both complexes, is an important component for the complexes' bactericidal activities, while the proteins are required both to solubilize

  2. A complex of equine lysozyme and oleic acid with bactericidal activity against Streptococcus pneumoniae.

    Science.gov (United States)

    Clementi, Emily A; Wilhelm, Kristina R; Schleucher, Jürgen; Morozova-Roche, Ludmilla A; Hakansson, Anders P

    2013-01-01

    HAMLET and ELOA are complexes consisting of oleic acid and two homologous, yet functionally different, proteins with cytotoxic activities against mammalian cells, with HAMLET showing higher tumor cells specificity, possibly due to the difference in propensity for oleic acid binding, as HAMLET binds 5-8 oleic acid molecules per protein molecule and ELOA binds 11-48 oleic acids. HAMLET has been shown to possess bactericidal activity against a number of bacterial species, particularly those with a respiratory tropism, with Streptococcus pneumoniae displaying the greatest degree of sensitivity. We show here that ELOA also displays bactericidal activity against pneumococci, which at lower concentrations shows mechanistic similarities to HAMLET's bactericidal activity. ELOA binds to S. pneumoniae and causes perturbations of the plasma membrane, including depolarization and subsequent rupture, and activates an influx of calcium into the cells. Selective inhibition of calcium channels and sodium/calcium exchange activity significantly diminished ELOA's bactericidal activity, similar to what we have observed with HAMLET. Finally, ELOA-induced death was also accompanied by DNA fragmentation into high molecular weight fragments - an apoptosis-like morphological phenotype that is seen during HAMLET-induced death. Thus, in contrast to different mechanisms of eukaryote cell death induced by ELOA and HAMLET, these complexes are characterized by rather similar activities towards bacteria. Although the majority of these events could be mimicked using oleic acid alone, the concentrations of oleic acid required were significantly higher than those present in the ELOA complex, and for some assays, the results were not identical between oleic acid alone and the ELOA complex. This indicates that the lipid, as a common denominator in both complexes, is an important component for the complexes' bactericidal activities, while the proteins are required both to solubilize and/or present the

  3. Copper Complexes of Nicotinic-Aromatic Carboxylic Acids as Superoxide Dismutase Mimetics

    Directory of Open Access Journals (Sweden)

    Virapong Prachayasittikul

    2008-12-01

    Full Text Available Nicotinic acid (also known as vitamin B3 is a dietary element essential for physiological and antihyperlipidemic functions. This study reports the synthesis of novel mixed ligand complexes of copper with nicotinic and other select carboxylic acids (phthalic, salicylic and anthranilic acids. The tested copper complexes exhibited superoxide dismutase (SOD mimetic activity and antimicrobial activity against Bacillus subtilis ATCC 6633, with a minimum inhibition concentration of 256 μg/mL. Copper complex of nicotinic-phthalic acids (CuNA/Ph was the most potent with a SOD mimetic activity of IC50 34.42 μM. The SOD activities were observed to correlate well with the theoretical parameters as calculated using density functional theory (DFT at the B3LYP/LANL2DZ level of theory. Interestingly, the SOD activity of the copper complex CuNA/Ph was positively correlated with the electron affinity (EA value. The two quantum chemical parameters, highest occupied molecular orbital (HOMO and lowest unoccupied molecular orbital (LUMO, were shown to be appropriate for understanding the mechanism of the metal complexes as their calculated energies show good correlation with the SOD activity. Moreover, copper complex with the highest SOD activity were shown to possess the lowest HOMO energy. These findings demonstrate a great potential for the development of value-added metallovitamin-based therapeutics.

  4. Comparative thermodynamic study on complex formation of native and hydroxypropylated cyclodextrins with benzoic acid

    Energy Technology Data Exchange (ETDEWEB)

    Terekhova, Irina V., E-mail: ivt@isc-ras.ru [Institute of Solution Chemistry of RAS, Ivanovo (Russian Federation)

    2011-11-10

    Highlights: Black-Right-Pointing-Pointer Comparative calorimetric study on complexation of benzoic acid by native and modified cyclodextrins was performed. Black-Right-Pointing-Pointer Van der Waals interactions are responsible for complex formation with {alpha}-cyclodextrins. Black-Right-Pointing-Pointer Complex formation of {beta}-cyclodextrins is governed by dehydration and hydrophobic interactions. Black-Right-Pointing-Pointer Binding of two benzoic acid molecules by {gamma}-cyclodextrins is driven by van der Waals interactions and solvent reorganization. Black-Right-Pointing-Pointer Hydroxypropyl groups favor binding of benzoic acid only with hydroxypropyl-{beta}-cyclodextrin. - Abstract: Complex formation of native and hydroxypropylated {alpha}-, {beta}- and {gamma}-cyclodextrins with benzoic acid in water was studied by means of calorimetry of solution at 298.15 K. The 1:1 complexes are formed with {alpha}- and {beta}-cyclodextrins, while 1:2 binding stoichiometry was observed for {gamma}-cyclodextrins. Thermodynamic parameters of complex formation of hydroxypropylated cyclodextrins were determined for the first time and analyzed. Comparison of binding affinity of native and modified cyclodextrins was carried out.

  5. Water Soluble Usnic Acid-Polyacrylamide Complexes with Enhanced Antimicrobial Activity against Staphylococcus epidermidis

    Directory of Open Access Journals (Sweden)

    Iolanda Francolini

    2013-04-01

    Full Text Available Usnic acid, a potent antimicrobial and anticancer agent, poorly soluble in water, was complexed to novel antimicrobial polyacrylamides by establishment of strong acidic-base interactions. Thermal and spectroscopic analysis evidenced a molecular dispersion of the drug in the polymers and a complete drug/polymer miscibility for all the tested compositions. The polymer/drug complexes promptly dissolved in water and possessed a greater antimicrobial activity against Staphylococcus epidermidis than both the free drug and the polymer alone. The best results were obtained with the complex based on the lowest molecular weight polymer and containing a low drug content. Such a complex showed a larger inhibition zone of bacterial growth and a lower minimum inhibitory concentration (MIC with respect to usnic acid alone. This improved killing effect is presumably due to the reduced size of the complexes that allows an efficient cellular uptake of the antimicrobial complexes. The killing effect extent seems to be not significantly dependent on usnic acid content in the samples.

  6. Transition Metal Complexes of 5-bromo Salicylaldehyde-2-furoic acid hydrazide; Synthesis and Characterisation

    Directory of Open Access Journals (Sweden)

    MANISH KUMAR

    2012-12-01

    Full Text Available A series of transition metal complexes of the ligand 5-bromo salicylaldehyde-2-furoic acid hydrazide have been prepared using Ti(III, Mn(III, V(III, Co(III, Fe(III, Ru(III and Rh(III. The complexes have been characterized by elemental analyses, melting points, molar conductance, magnetic susceptibility measurement, electronic and infra red spectral studies. Based on these studies octahedral structures have been proposed for these complexes. The ligand has behaved in dibasic tridentate manner. The I.R. spectra of the complexes revealed non-participation of furan ring oxygen in coordination with the metal ions.

  7. Condensation Polymers of Terephthalic Acid and 1,4-Diaminobutane and Their Schiff Base Complexes

    Directory of Open Access Journals (Sweden)

    Sandeep Rai

    2013-01-01

    Full Text Available Amino-terminated oligomeric poly(tetramethylene terephthalamide (PTTA was prepared by condensation of terephthalic acid and 1,4-diaminobutane using phosphorylation technique. Schiff base complexes of this polyamide were synthesized with salicylaldehyde and 2-hydroxy-1-naphthaldehyde complexes of Co(II, Ni(II, and Cu(II. The polyamide as well as Schiff base complexes were characterized by elemental analysis, IR spectroscopy, and magnetic susceptibility measurements. Thermal stabilities of ligand and its various complexes were compared by thermogravimetric analysis.

  8. Sequence and structural features of binding site residues in protein-protein complexes: comparison with protein-nucleic acid complexes

    Directory of Open Access Journals (Sweden)

    Selvaraj S

    2011-10-01

    Full Text Available Abstract Background Protein-protein interactions are important for several cellular processes. Understanding the mechanism of protein-protein recognition and predicting the binding sites in protein-protein complexes are long standing goals in molecular and computational biology. Methods We have developed an energy based approach for identifying the binding site residues in protein–protein complexes. The binding site residues have been analyzed with sequence and structure based parameters such as binding propensity, neighboring residues in the vicinity of binding sites, conservation score and conformational switching. Results We observed that the binding propensities of amino acid residues are specific for protein-protein complexes. Further, typical dipeptides and tripeptides showed high preference for binding, which is unique to protein-protein complexes. Most of the binding site residues are highly conserved among homologous sequences. Our analysis showed that 7% of residues changed their conformations upon protein-protein complex formation and it is 9.2% and 6.6% in the binding and non-binding sites, respectively. Specifically, the residues Glu, Lys, Leu and Ser changed their conformation from coil to helix/strand and from helix to coil/strand. Leu, Ser, Thr and Val prefer to change their conformation from strand to coil/helix. Conclusions The results obtained in this study will be helpful for understanding and predicting the binding sites in protein-protein complexes.

  9. Preparation and spectral investigation of inclusion complex of caffeic acid with hydroxypropyl-beta-cyclodextrin.

    Science.gov (United States)

    Zhang, Min; Li, Jinxia; Zhang, Liwei; Chao, Jianbin

    2009-01-01

    The inclusion complexation behavior of caffeic acid (CA) with hydroxypropyl-beta-cyclodextrin (HP-beta-CD) was studied by UV-vis, fluorescence spectroscopy and nuclear magnetic resonance spectroscopy (NMR). Experimental conditions including the concentration of HP-beta-CD and media acidity were investigated in detail. The result suggested HP-beta-CD was more suitable for including CA in acidity solution. The binding contants (K) of the inclusion complexes were determined by linear regression analysis and the inclusion ratio was found to be 1:1. The water solubility of CA was increased by inclusion with HP-beta-CD according to the phase-solubility diagram. The spatial configuration of complex has been proposed based on (1)H NMR and two-dimensional (2D) NMR, the result suggested that CA was entrapped inside the hydrophobic core of HP-beta-CD with the lipophilic aromatic ring and the portion of ethylene.

  10. Communication: Physical origins of ionization potential shifts in mixed carboxylic acids and water complexes

    Science.gov (United States)

    Gu, Quanli; Tang, Zhen; Su, Peifeng; Wu, Wei; Yang, Zhijun; Trindle, Carl O.; Knee, Joseph L.

    2016-08-01

    The ionization potential (IP) of the aromatic alpha hydroxy carboxylic acid, 9-hydroxy-9-fluorene carboxylic acid (9HFCA), is shifted by complexation with hydrogen bonding ligands such as water and formic acid. Generalized Kohn-Sham energy decomposition analysis decomposes the intermolecular binding energies into a frozen energy term, polarization, correlation, and/or dispersion energy terms, as well as terms of geometric relaxation and zero point energy. We observe that in each dimer the attractive polarization always increases upon ionization, enhancing binding in the cation and shifting the IP toward the red. For 9HFCA—H2O, a substantial decrease of the repulsive frozen energy in cation further shifts the IP toward red. For 9HFCA—HCOOH, the increase of the frozen energy actually occurs in the cation and shifts the IP toward blue. Consistent with the experimental measurements, our analysis provides new, non-intuitive perspectives on multiple hydrogen bonds interactions in carboxylic acids and water complexes.

  11. Preparation and Property of Acrylic Acid Rare Earth Complex and Its Hydrosilylation

    Institute of Scientific and Technical Information of China (English)

    Zhang Ming; Chen Haiyan; Chen Xiaosong; Dai Shaojun; Inoue Shinich; Okamoto Hiroshi

    2004-01-01

    Acrylic acid rare earth complex was prepared. Its chemical composition was determined by chemical and elemental analysis, and its structure as well as properties was characterized using IR, Fluorescence and UV spectrum, and its solubility was also investigated. Meanwhile a kind of elastic functional polymer with rare earth units in the side chains was produced. It is confirmed by IR spectrum that the Si-H bonds really react with acrylic acid rare earth.

  12. Synthesis, oxygenation and catalytic performance of manganese complex with p-aminomethyl benzoic acid Schiff base

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The amino acid Schiff base complex (Sal-AMBA-Mn) was prepared with p-amino-methylbenzoic acid, salicylaldehyde N-dimethylformamide solution was investigated. The results show that lower temperature is in favor of the oxygenation, and energy,dehydroepiandrosterone acetate is effectively oxidized by molecular oxygen and the corresponding enone 7-keto-dehydroepiandrosterone acetate is obtained. The yield is 62.1% when the oxidation is carried out under the reaction conditions of 60℃C, 2 MPa of O2 pressure, C5H5N as a solvent and molar ratio of the substrate to the complex of 1:10.

  13. Electrocatalytic and simultaneous determination of isoproterenol, uric acid and folic acid at molybdenum (VI) complex-carbon nanotube paste electrode

    Energy Technology Data Exchange (ETDEWEB)

    Beitollahi, Hadi, E-mail: h.beitollahi@yahoo.com [Environment Department, Research Institute of Environmental Sciences, International Center for Science, High Technology and Environmental Sciences, Kerman (Iran, Islamic Republic of); Sheikhshoaie, Iran [Department of Chemistry, Faculty of Science, Shahid Bahonar University of Kerman, Kerman 76175-133 (Iran, Islamic Republic of)

    2011-11-30

    Highlights: > A molybdenum (VI) complex-carbon nanotube paste electrode have been fabricated. > This electrode reduced the oxidation potential of isoproterenol by about 175 mV. > It resolved the voltammetric waves of isoproterenol, uric acid and folic acid. - Abstract: This paper describes the development, electrochemical characterization and utilization of a novel modified molybdenum (VI) complex-carbon nanotube paste electrode for the electrocatalytic determination of isoproterenol (IP). The electrochemical profile of the proposed modified electrode was analyzed by cyclic voltammetry (CV) that showed a shift of the oxidation peak potential of IP at 175 mV to less positive value, compared with an unmodified carbon paste electrode. Differential pulse voltammetry (DPV) in 0.1 M phosphate buffer solution (PBS) at pH 7.0 was performed to determine IP in the range from 0.7 to 600.0 {mu}M, with a detection limit of 35.0 nM. Then the modified electrode was used to determine IP in an excess of uric acid (UA) and folic acid (FA) by DPV. Finally, this method was used for the determination of IP in some real samples.

  14. Removal of Aqueous Boron by Using Complexation of Boric Acid with Polyols: A Raman Spectroscopic Study

    Energy Technology Data Exchange (ETDEWEB)

    Eom, Ki Heon; Jeong, Hui Cheol; An, Hye Young; Lim, Jun-Heok; Lee, Jea-Keun; Won, Yong Sun [Pukyong National University, Busan (Korea, Republic of)

    2015-12-15

    Boron is difficult to be removed from seawater by simple RO (reverse osmosis) membrane process, because the size of boric acid (B(OH){sub 3}), the major form of aqueous boron, is as small as the nominal pore size of RO membrane. Thus, the complexation of boric acid with polyols was suggested as an alternative way to increase the size of aqueous boron compounds and the complexation behavior was investigated with Raman spectroscopy. As a reference, the Raman peak for symmetric B-O stretching vibrational mode both in boric acid and borate ion (B(OH){sub 4}{sup -}) was selected. A Raman peak shift (877 cm{sup -1} →730 cm{sup -1}) was observed to confirm that boric acid in water is converted to borate ion as the pH increases, which is also correctly predicted by frequency calculation. Meanwhile, the Raman peak of borate ion (730 cm{sup -1}) did not appear as the pH increased when polyols were applied into aqueous solution of boric acid, suggesting that the boric acid forms complexing compounds by combining with polyols.

  15. Functionalization of conducting polymer with novel Co(II) complex: Electroanalysis of ascorbic acid

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, Swati [School of Materials Science and Technology, Institute of Technology, Banaras Hindu University, Varanasi 221005 (India); Prakash, Rajiv, E-mail: rajivprakash12@yahoo.com [School of Materials Science and Technology, Institute of Technology, Banaras Hindu University, Varanasi 221005 (India)

    2010-06-15

    We report for the first time the functionalization of a conducting polymer with a metal complex in order to develop a new type of catalytic material exhibiting better electronic communication through their delocalized {pi} electrons. The Co(II) complex having hydroxyl group as functional moiety is chemically coupled with carboxyl group of polyanthranilic acid which itself is a self doped conducting polymer. The covalent linkage between Co(II) and -OH group is confirmed using UV-vis, FT-IR and NMR spectroscopic techniques. The Co(II) complex functionalized polymer does exhibit excellent redox behavior and stability with mixed properties of Co(II) complex and {pi}-conjugated polymer. The material possesses potential benefits in sensors/biosensor applications and it is demonstrated for the electroanalysis of ascorbic acid at a level of nano molar concentration.

  16. Experimental and theoretical investigation of the complexation of methacrylic acid and diisopropyl urea

    Science.gov (United States)

    Pogány, Peter; Razali, Mayamin; Szekely, Gyorgy

    2017-01-01

    The present paper explores the complexation ability of methacrylic acid which is one of the most abundant functional monomer for the preparation of molecularly imprinted polymers. Host-guest interactions and the mechanism of complex formation between methacrylic acid and potentially genotoxic 1,3-diisopropylurea were investigated in the pre-polymerization solution featuring both experimental (NMR, IR) and in silico density functional theory (DFT) tools. The continuous variation method revealed the presence of higher-order complexes and the appearance of self-association which were both taken into account during the determination of the association constants. The quantum chemical calculations - performed at B3LYP 6-311 ++G(d,p) level with basis set superposition error (BSSE) corrections - are in agreement with the experimental observations, reaffirming the association constants and justifying the validity of computational investigation of such systems. Furthermore, natural bond orbital analysis was carried out to appraise the binding properties of the complexes.

  17. Synthesis and Structure Elucidation of Cr(III Complexes of Polydentate Hydroxamic Acid Ligands

    Directory of Open Access Journals (Sweden)

    K.P. SRIVASTAVA

    2013-06-01

    Full Text Available The ligands α-mercaptobenzacetohydroxamic acid (MBAHA-H and 2-amino-α-mercaptobenzacetohydroxamic acid (AMBAHA-H and their different mixed ligand novel complexes with CrIII having specific formulae have been synthesized and characterised by elemental analyses, magnetic and conductance measurements, IR and electronic spectral studies. The ligands were found to behave as monobasic tridentate (SO’O donor and tetradentate (SO’ ON donor manner respectively. All the synthesized CrIII complexes were non-electrolyte with magnetic moment ranging from 3.79 to 3.87 BM. The structural assessment of the complexes has been carried out based on spectral studies (electronic&infrared and molar conductivity values. All the complexes were found to be of octahedral geometry.

  18. Recognition of amino acids and anions by a Zn(Ⅱ)-methylazacalix[4]pyridine complex

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    As a powerful macrocyclic host molecule with unique conformation and cavity structure that are fine-tuned by the bridging nitrogen atoms, methylazacalix[4]pyridine (MACP-4) has been shown to selectively recognize Zn2+ and form stable Zn(Ⅱ)-MACP-4 complexes both in solid state and solution with an association constant up to 5.97 (logKs). The molecular recognition of Zn(Ⅱ)-MACP-4 complexes towards various amino acids and anions with different geometry was investigated by using the spectral titration methods and X-ray analysis. The Zn(Ⅱ)-MACP-4 complex was found to recognize the 17 amino acids tested with the association constant up to 3.97 (logKs). On the other hand, the Zn(Ⅱ)-MACP-4 complex selectively interacted with anions and the maximum association constant of 3.9 (logKs) was obtained.

  19. Synthesis and spectroscopic studies of iron (III) complex with a quinolone family member (pipemidic acid)

    Science.gov (United States)

    Skrzypek, D.; Szymanska, B.; Kovala-Demertzi, Dimitra; Wiecek, Joanna; Talik, E.; Demertzis, Mavroudis A.

    2006-12-01

    The interaction of iron (III) with pipemidic acid, Hpipem, afforded the complex [Fe (pipem) (HO)2 (H2O)]2. The new complex has been characterised by elemental analyses, infra-red, EPR and XPS spectroscopies. The monoanion, pipem, exhibits O, O ligation through the carbonyl and carboxylato oxygen atoms. Six coordinate dimer distorted octahedral configuration has been proposed for [Fe (pipem) (HO)2 (H2O)]2.

  20. Prediction of Decomposition Temperature for Lanthanide Complexes Involving Cyclopentadienyl and Benzohydroxamic Acid Ligand by ANNs

    Institute of Scientific and Technical Information of China (English)

    孙益民; 凌青; 万玉宝; 王修然; 宇海银

    2002-01-01

    The decomposition temperatures of the lanthanide organic complexes(η5-C5H5)2Ln(C6H5CONHO)involving cyclopentadienyl and benzohydroxamic acid ligands were calculated and predicted by the model based on ANNs(artificial neural netowrks)method.The comparison was carried out between results from ANNs method and traditinal regression method.It is proved that ANNs could be used more efficiently for the prediction of decomposition temperature of lanthanide organic complexes.

  1. Prediction of Decomposition Temperature for Lanthanide Complexes Involving Cyclopentadienyl and Benzohydroxamic Acid Ligand by ANNs

    Institute of Scientific and Technical Information of China (English)

    SUN,Yi-Min(孙益民); LING,Qing(凌青); WAN,Yu-Bao(万玉宝); WANG,Xiu-Ran(王修然); YU,Hai-Yin(宇海银)

    2002-01-01

    The decomposition temperatures of the lanthanide organic complexes (η5-C5H5)2Ln(C6H5CONHO) involving cyclopentadienyl and benzohydroxamic acid ligands were calculated and predicted by the model based on ANNs (artificial neural networks)method. The comparison was carried out between results from ANNs method and traditional regression method. It is proved that ANNs could be used more efficiently for the prediction of decomposition temperature of lanthanide organic complexes.

  2. Hydrogen bonding in oxalic acid and its complexes: A database study of neutron structures

    Indian Academy of Sciences (India)

    R Chitra; Amit Das; R R Choudhury; M Ramanadham; R Chidambaram

    2004-08-01

    The basic result of carboxylic group that the oxygen atom of the –OH never seems to be a hydrogen bond acceptor is violated in the cases, namely urea oxalic acid and bis urea oxalic acid complexes, where the hydroxyl oxygen atom is an acceptor of a weak N–H... O hydrogen bond. The parameters of this hydrogen bond, respectively in these structures are: hydrogen acceptor distance 2.110 Å and 2.127 Å and the bending angle at hydrogen, 165.6° and 165.8°. The bond strength around the hydroxyl oxygen is close to 1.91 valence units, indicating that it has hardly any strength left to form hydrogen bonds. These two structures being highly planar, force the formation of this hydrogen bond. As oxalic acid is the common moiety, the structures of the two polymorphs, -oxalic acid and -oxalic acid, also were looked into in terms of hydrogen bonding and packing.

  3. Defluoridation of water using dicarboxylic acids mediated chitosan-polyaniline/zirconium biopolymeric complex.

    Science.gov (United States)

    Muthu Prabhu, Subbaiah; Meenakshi, Sankaran

    2016-04-01

    The present investigation describes the preparation of hydrogen bonded chitosan-polyaniline/zirconium biopolymeric matrix by grafting method under dicarboxylic acid medium for the removal of fluoride, first time. Herein, the dicarboxylic acids, oxalic acid, malonic acid, succinic acid were used as medium. The synthesized complex was characterized by usual analytical techniques like FTIR, XRD, SEM and EDAX analysis. From the batch equilibrium experiments, the maximum defluoridation capacity (DC) was found to be 8.713 mg/g at room temperature with the minimum contact time of 24 min at 100mg of the sorbent dosage. The temperature study results of adsorption kinetics showed the adsorption behavior could be better described by the pseudo-second-order equation than pseudo-first-order kinetic model. The adsorption isotherm was well fitted by the Freundlich equation rather than Langmuir and D-R isotherms. The mechanism of fluoride removal was ligand exchange at neutral pH and electrostatic attraction at acidic pH of the medium. Regeneration studies were carried out to identify the best regenerant which makes the process cost-effective. Conclusions of this work demonstrate the potential applicability of the dicarboxylic acid mediated chitosan-polyaniline/zirconium complex as an effective adsorbent for fluoride removal from water.

  4. Effect of complex amino acid imbalance on growth of tumor in tumor-bearing rats

    Institute of Scientific and Technical Information of China (English)

    Yin-Cheng He; Yuan-Hong Wang; Jun Cao; Ji-Wei Chen; Ding-Yu Pan; Ya-Kui Zhou

    2003-01-01

    AIM: To investigate the effect of complex amino acid imbalance on the growth of tumor in tumor-bearing (TB) rats.METHODS: Sprague-Dawlley (SD) rats underwent jejunostomy for nutritional support. A suspension of Walker256 carcinosarcoma cells was subcutaneously inoculated.TB rats were randomly divided into groups A, B, C and D according to the formula of amino acids in enteral nutritional solutions, respectively. TB rats received jejunal feedings supplemented with balanced amino acids (group A),methionine-depleted amino acids (group B), valine-depleted amino acids (group C) and methionine- and valine-depleted complex amino acid imbalance (group D) for 10 days. Tumor volume, inhibitory rates of tumor, cell cycle and life span of TB rats were investigated.RESULTS: The G0/G1 ratio of tumor cells in group D (80.5±9.0) % was higher than that in groups A, B and C which was 67.0±5.1 %, 78.9±8.5 %, 69.2±6.2 %, respectively (P<0.05). The ratio of S/G2M and PI in group D were lower than those in groups A, B and C. The inhibitory rate of tumor in groups B, C and D was 37.2 %, 33.3 % and 43.9 %,respectively (P<0.05). The life span of TB rats in group D was significantly longer than that in groups B, C, and A.CONCLUSION: Methionine/valine-depleted amino acid imbalance can inhibit tumor growth. Complex amino acids of methionine and valine depleted imbalance have stronger inhibitory effects on tumor growth.

  5. Characterization of folic acid/native cyclodextrins host-guest complexes in solution

    Science.gov (United States)

    Ceborska, Magdalena; Zimnicka, Magdalena; Wszelaka-Rylik, Małgorzata; Troć, Anna

    2016-04-01

    The complexation of folic acid (FA) with native cyclodextrins was studied and this process was used for the comparison of 1H NMR, ITC and ESIMS for the evaluation of association constants. The stability increases in the series: α-cyclodextrin/FA < γ-cyclodextrin/FA < β-cyclodextrin/FA. 1H NMR and ITC gave comparable results in regard to association constant values, while results obtained for MS were considerably higher due to different interactions (electrostatic instead of hydrophobic) responsible for the stabilization of the complexes. The dimerization of FA in water was also studied, as well as its impact on the process of complexation with native cyclodextrins.

  6. Chemodynamics of metal complexation by natural soft colloids: Cu(II) binding by humic acid

    NARCIS (Netherlands)

    Town, R.M.; Duval, J.F.L.; Buffle, J.; Leeuwen, van H.P.

    2012-01-01

    The chemodynamics of Cu(II) complexation by humic acid is interpreted in terms of recently developed theory for permeable charged nanoparticles. Two opposing electric effects are operational with respect to the overall rate of association, namely, (i) the conductive enhancement of the diffusion of

  7. Complex formation and solubility of Pu(IV) with malonic and succinic acids

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, T.; Kobayashi, T.; Takagi, I.; Moriyama, H. [Kyoto Univ. (Japan). Dept. of Nuclear Engineering; Fujiwara, A. [Radioactive Waste Management Funding and Research Center, Tokyo (Japan); Kulyako, Y.M.; Perevalov, S.A.; Myasoedov, B.F. [Russian Academy of Sciences (RAS), Moscow (RU). V.I. Vernadsky Inst. of Geochemistry and Analytical Chemistry (GEOKHI)

    2009-07-01

    The complex formation constants of tetravalent plutonium ion with malonic and succinic acids in aqueous solution were determined by the solvent-extraction method. Also, by taking the known values of the solubility products, the hydrolysis constants and the formation constants, the experimental solubility data of plutonium in the presence of carboxylates were analyzed. (orig.)

  8. Oxalic acid complexes: Promising draw solutes for forward osmosis (FO) in protein enrichment

    KAUST Repository

    Ge, Qingchun

    2015-01-01

    Highly soluble oxalic acid complexes (OACs) were synthesized through a one-pot reaction. The OACs exhibit excellent performance as draw solutes in FO processes with high water fluxes and negligible reverse solute fluxes. Efficient protein enrichment was achieved. The diluted OACs can be recycled via nanofiltration and are promising as draw solutes.

  9. Synthesis and cofluorescence of Eu(Y) complexes with salicylic acid and o-phenanthroline

    Science.gov (United States)

    Xu, Cun-Jin; Xie, Fei; Guo, Xing-Zhong; Yang, Hui

    2005-07-01

    A series of dinuclear complexes of salicylic acid (HSal) and o-phenanthroline (Phen) with different molar ratios of Eu 3+ to Y 3+ have been synthesized. Their compositions are Eu xY 1-x (Sal) 3(Phen) ( x = 0 ˜ 1). Their UV spectra, IR spectra, and fluorescence spectra were studied. The UV spectra of the complexes reflect essentially absorption of the ligands for the fact that no obvious change of wavelength and band shape is found between the spectra of the complexes and that of the ligands except slight red shift. The IR absorption spectra indicate that salicylic acid is coordinated to the rare earth ions and chemical bonds are formed between rare earth ions and nitrogen atoms of o-phenanthroline. The fluorescence spectra of the complexes indicate that the fluorescence emission intensity of europium ion was enhanced by the addition of Y 3+, which is referred to as cofluorescence. These facts show that not only the ligands but also the yttrium complex can transfer the absorbed energy to Eu 3+ ion in the complexes. Formation of polynuclear complexes appears to be responsible for cofluorescence.

  10. Controlled Release of Doxorubicin from Doxorubicin/γ-Polyglutamic Acid Ionic Complex

    Directory of Open Access Journals (Sweden)

    Bhavik Manocha

    2010-01-01

    Full Text Available Formation of drug/polymer complexes through ionic interactions has proven to be very effective for the controlled release of drugs. The stability of such drug/polymer ionic complexes can be greatly influenced by solution pH and ionic strength. The aim of the current work was to evaluate the potential of γ-polyglutamic acid (γ-PGA as a carrier for the anticancer drug, Doxorubicin (DOX. We investigated the formation of ionic complexes between γ-PGA and DOX using scanning electron microscopy, spectroscopy, thermal analysis, and X-ray diffraction. Our studies demonstrate that DOX specifically interacts with γ-PGA forming random colloidal aggregates and results in almost 100% complexation efficiency. In vitro drug release studies illustrated that these complexes were relatively stable at neutral pH but dissociates slowly under acidic pH environments, facilitating a pH-triggered release of DOX from the complex. Hydrolytic degradation of γ-PGA and DOX/γ-PGA complex was also evaluated in physiological buffer. In conclusion, these studies clearly showed the feasibility of γ-PGA to associate cationic drug such as DOX and that is may serve as a new drug carrier for the controlled release of DOX in malignant tissues.

  11. Methods of staining target chromosomal DNA employing high complexity nucleic acid probes

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Joe W.; Pinkel, Daniel; Kallioniemi, Ol' li-Pekka; Kallioniemi, Anne; Sakamoto, Masaru

    2006-10-03

    Methods and compositions for staining based upon nucleic acid sequence that employ nucleic acid probes are provided. Said methods produce staining patterns that can be tailored for specific cytogenetic analyses. Said probes are appropriate for in situ hybridization and stain both interphase and metaphase chromosomal material with reliable signals. The nucleic acid probes are typically of a complexity greater than 50 kb, the complexity depending upon the cytogenetic application. Methods and reagents are provided for the detection of genetic rearrangements. Probes and test kits are provided for use in detecting genetic rearrangements, particularly for use in tumor cytogenetics, in the detection of disease related loci, specifically cancer, such as chronic myelogenous leukemia (CML), retinoblastoma, ovarian and uterine cancers, and for biological dosimetry. Methods and reagents are described for cytogenetic research, for the differentiation of cytogenetically similar but genetically different diseases, and for many prognostic and diagnostic applications.

  12. Electrochemical and spectroscopic studies of the complexed species of models of nitrohumic acids derived from phthalic acid

    Directory of Open Access Journals (Sweden)

    Mercê Ana Lucia Ramalho

    1998-01-01

    Full Text Available The study of model compounds is necessary in order to obtain information about complex organic substances as in the case of humic substances (HS. These substances are potential organic fertilizers and have other important functions in soils, natural waters and organic sediments. The main chemical properties of the complexes formed from 3-nitrophthalic and 4-nitrophthalic acids and the metal ions Fe(III and Zn(II were studied using potentiometric titrations, ultraviolet-visible spectroscopy (UV-Vis and cyclic voltammetry (CV. A trial potentiometric titration was done with a mixture of the models for nitrohumic acids and Cu(II. Equilibrium constants for the systems were calculated and UV-Vis and CV were employed to monitor the formation of the species. Comparative studies involving chelating centres of nitrosalicylic acids and nitrocatechols with Fe(III, Zn(II and Cu(II are presented. The initial studies involving the nitrohumic substances (NHS, a laboratory artifact of HS have been made and good evidence was found for the further use of NHS as a potential organic fertilizer as well as HS. In this present work one of the observed advantages of NHS over HS was that some aromatic nitro- centres can bind some metal ions at p[H] values of normal soils, near 7.0 to 7.5.

  13. Synthesis and Characterization of Terbium-Trimesic Acid Luminescent Complex in Polyvinylpyrrolidone Matrix

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Tb(Ⅲ)-trimesic acid (TMA) luminescent complexes were synthesized in the polyvinylpyrrolidone (PVP) matrix. The elemental analysis, inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and fourier-transform infrared spectroscopy (FT-IR) indicated that its chemical constitution is PVP/Tb(MTA)·4H2O. The XRD patterns showed that the complex is a new kind of crystal. The TEM image indicates that the complex is rod shaped. The rod diameter is about 200 nm, and the length ranges from hundred of nanometer to a few micrometers. In addition, the dispersity is better. TG-DTA curves indicate that the complex is thermally stable before 463 ℃. Photoluminescence analysis indicates that the complex emits Tb3+ characteristic luminescence under ultraviolet excitation.

  14. Lanthanide amino acid Schiff base complexes: synthesis, spectroscopic characterization, physical properties and in vitro antimicrobial studies

    Institute of Scientific and Technical Information of China (English)

    Samir Alghool; M.Sh.Zoromba; Hanan F.Abd El-Halim

    2013-01-01

    Complexes of La (Ⅲ),Nd(Ⅲ),Gd(Ⅲ),Sm(Ⅲ),and Ce(Ⅳ) were synthesized with Schiff base [(3,5-di-tert-butyl-2-hydroxybenzyl) amino] acetic acid (H3L).The ligand and its complexes were synthesized and characterized based on the following analysis:elemental analyses,FAB-mass,molar conductance measurements,magnetic measurement,UV-visible,IR,and NMR spectral studies.The spectral data revealed that the ligand acted as a neutral tridentate coordinating to metal ion through ONO donor sequence.Thermal degradation studies of the ligand and its complexes showed that the previous lanthanide complexes were more thermally stable than the ligand itself.The Schiff base and its complexes were screened for their antibacterial (Escherichia coli,Staphylococcus aureus) and antifungal (Aspergillus flavus and Candida Albicans).

  15. Synthesis, characterisation and biological evaluation of copper and silver complexes based on acetylsalicylic acid.

    Science.gov (United States)

    Rubner, Gerhard; Bensdorf, Kerstin; Wellner, Anja; Bergemann, Silke; Gust, Ronald

    2011-10-01

    Metalcarbonyl complexes with ligands derived from acetylsalicylic acid demonstrated high cytotoxic potential against various tumor cell lines and strong inhibition of the cyclooxygenase enzymes COX-1 and 2. In this study we tried to achieve comparable effects with [alkyne]silver or copper trifluoromethanesulfonate complexes which are more hydrophilic then the uncharged metalcarbonyl derivatives. All compounds were evaluated for growth inhibition against breast (MCF-7, MDA-MB 231) and colon cancer (HT-29) cell lines and for COX-1 and COX-2 inhibitory effects at isolated isoenzymes. Pure ligands showed neither cytotoxic nor COX-inhibitory effects. While the silver complexes of (but-2-ynyl)-2-acetoxybenzoate (But-ASS-Ag) and (but-2-yne-1,4-diyl)-bis(2-acetoxybenzoate) (Di-ASS-But-Ag) were strong cytostatics, only the copper complex Di-ASS-But-Cu was active. At the COX enzymes the complexes were more effective than their ligands and aspirin.

  16. Theoretical and spectroscopic studies of lanthanum (III) complex of 5-aminoorotic acid

    Science.gov (United States)

    Kostova, Irena; Peica, Niculina; Kiefer, Wolfgang

    2006-09-01

    The lanthanum (III) complex of 5-aminoorotic acid (HAOA) was synthesized and its structure was determined by means of elemental analysis and IR, Raman, and 1H NMR spectroscopies. Significant differences in the IR, Raman, and 1H NMR spectra of the complex were observed as compared to the spectra of the ligand. The geometry of 5-aminoorotic acid was computed and optimized with the Gaussian 03 program employing the B3PW91 and B3LYP methods with the 6-311++G and LANL2DZ basis sets, while the geometry of the La(III) complex of 5-aminoorotic acid was also calculated and optimized with B3PW91/LANL2DZ and B3LYP/LANL2DZ methods. The density functional calculations revealed that the binding mode in the complex was bidentate through the carboxylic oxygen atoms. Detailed vibrational analysis of HAOA and La(III)-AOA systems based on both the calculated and experimental spectra confirmed the suggested metal-ligand binding mode. The density functional theory (DFT) calculated geometries, harmonic vibrational wavenumbers including IR and Raman scattering activities for the ligand and its La(III) complex were in good agreement with the experimental data, a complete vibrational assignment being proposed.

  17. Stability on the 109Cd, 65Zn Complex with Humus Acids

    Institute of Scientific and Technical Information of China (English)

    HUA Luo; CHEN Shi-bao; BAI Ling-yu; WEI Dong-pu

    2002-01-01

    The radioactive isotope tracer and ion exchange balanced method was used to study the stability of 109Cd, 65 Zn complexes with humus acids. In the 109Cd and 65 Zn single existing system with humic acids,the stability constants of the humic-109 Cd (65 Zn) complex compound was higher than the fulvic-109 Cd (65 Zn)complex compound. The stability constant of the humic (fulvic) -65Zn was higher than that of the humic (fulvic)-109Cd. In the 109Cd and 65 Zn coexisting system, the stability constant and the co-ordination number of the humic (fulvic)-65Zn complex obviously increased, but the stability constant and the co-ordination number of the humic (fulvic)-109Cd complex obviously decreased as compared with its respectively single existing system.The result showed that the humus matter with higher molecular weight could more effectively reduce plant availability of heavy metals than that with lower molecular weight in polluted soil by heavy metals. The humus matter could more effectively reduce plant availability of Zn than that of Cd. Application of humus-acid increased the harm of Cd and decreased the harm of Zn to plants in Cd-Zn coexisting system.

  18. Thermodynamics of mixed-ligand complex formation of mercury (II) ethylenediaminetetraacetate with amino acids in solution

    Energy Technology Data Exchange (ETDEWEB)

    Pyreu, Dmitrii, E-mail: pyreu@mail.ru [Department of Inorganic and Analytic Chemistry, Ivanovo State University, Ermak 39, Ivanovo 153025 (Russian Federation); Kozlovskii, Eugenii [Department of Inorganic and Analytic Chemistry, Ivanovo State University, Ermak 39, Ivanovo 153025 (Russian Federation); Gruzdev, Matvei; Kumeev, Roman [Institute of Solution Chemistry, Ivanovo (Russian Federation)

    2012-11-20

    Highlights: Black-Right-Pointing-Pointer Stable mixed ligand complexes of HgEdta with amino acids at physiological pH value. Black-Right-Pointing-Pointer The thermodynamic and NMR data evident the ambidentate coordination mode of arginine. Black-Right-Pointing-Pointer Participation of the guanidinic group of Arg in coordination process. Black-Right-Pointing-Pointer Binuclear complexes (HgEdta){sub 2}L with the bridging function of amino acid. - Abstract: The mixed-ligand complex formation in the systems Hg{sup 2+} - Edta{sup 4-} - L{sup -}(L = Arg, Orn, Ser) has been studied by means of calorimetry, pH-potentiometry and NMR spectroscopy in aqueous solution at 298.15 K and the ionic strength of I = 0.5 (KNO{sub 3}). The thermodynamic parameters of formation of the HgEdtaL, HgEdtaHL and (HgEdta){sub 2}L complexes have been determined. The most probable coordination mode for the complexone and the amino acid in the mixed-ligand complexes was discussed.

  19. Synthesis, Crystal Structure, and Thermal Decomposition of the Cobalt(II Complex with 2-Picolinic Acid

    Directory of Open Access Journals (Sweden)

    Di Li

    2014-01-01

    Full Text Available The cobalt(II complex of 2-picolinic acid (Hpic, namely, [Co(pic2(H2O2]·2H2O, was synthesized with the reaction of cobalt acetate and 2-picolinic acid as the reactants by solid-solid reaction at room temperature. The composition and structure of the complex were characterized by elemental analysis, infrared spectroscopy, single crystal X-ray diffraction, and thermogravimetry-differential scanning calorimetry (TG-DSC. The crystal structure of the complex belongs to monoclinic system and space group P2(1/n, with cell parameters of a=9.8468(7 Å, b=5.2013(4 Å, c=14.6041(15 Å, β=111.745(6°, V=747.96(11 Å3, Z=2, Dc=1.666 g cm−3, R1=0.0297, and wR2=0.0831. In the title complex, the Co(II ion is six-coordinated by two pyridine N atoms and two carboxyl O atoms from two 2-picolinic acid anions, and two O atoms from two H2O molecules, and forming a slightly distorted octahedral geometry. The thermal decomposition processes of the complex under nitrogen include dehydration and pyrolysis of the ligand, and the final residue is cobalt oxalate at about 450°C.

  20. A comparative study of the complexation of uranium(VI) withoxydiacetic acid and its amide derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Linfeng; Tian, Guoxin

    2005-05-01

    There has been significant interest in recent years in the studies of alkyl-substituted amides as extractants for actinide separation because the products of radiolytic and hydrolytic degradation of amides are less detrimental to separation processes than those of organophosphorus compounds traditionally used in actinide separations. Stripping of actinides from the amide-containing organic solvents is relatively easy. In addition, the amide ligands are completely incinerable so that the amount of secondary wastes generated in nuclear waste treatment could be significantly reduced. One group of alkyl-substituted oxa-diamides have been shown to be promising in the separation of actinides from nuclear wastes. For example, tetraoctyl-3-oxa-glutaramide and tetraisobutyl-oxa-glutaramide form actinide complexes that can be effectively extracted from nitric acid solutions. To understand the thermodynamic principles governing the complexation of actinides with oxa-diamides, we have studied the complexation of U(VI) with dimethyl-3-oxa-glutaramic acid (DMOGA) and tetramethyl-3-oxa-glutaramide (TMOGA) in aqueous solutions, in comparison with oxydiacetic acid (ODA) (Figure 1). Previous studies have indicated that the complexation of U(VI) with ODA is strong and entropy-driven. Comparing the results for DMOGA and TMOGA with those for ODA could provide insight into the energetics of amide complexation with U(VI) and the relationship between the thermodynamic properties and the ligand structure.

  1. Binding modes of aromatic ligands to mammalian heme peroxidases with associated functional implications: crystal structures of lactoperoxidase complexes with acetylsalicylic acid, salicylhydroxamic acid, and benzylhydroxamic acid.

    Science.gov (United States)

    Singh, Amit K; Singh, Nagendra; Sinha, Mau; Bhushan, Asha; Kaur, Punit; Srinivasan, Alagiri; Sharma, Sujata; Singh, Tej P

    2009-07-24

    The binding and structural studies of bovine lactoperoxidase with three aromatic ligands, acetylsalicylic acid (ASA), salicylhydoxamic acid (SHA), and benzylhydroxamic acid (BHA) show that all the three compounds bind to lactoperoxidase at the substrate binding site on the distal heme side. The binding of ASA occurs without perturbing the position of conserved heme water molecule W-1, whereas both SHA and BHA displace it by the hydroxyl group of their hydroxamic acid moieties. The acetyl group carbonyl oxygen atom of ASA forms a hydrogen bond with W-1, which in turn makes three other hydrogen-bonds, one each with heme iron, His-109 N(epsilon2), and Gln-105 N(epsilon2). In contrast, in the complexes of SHA and BHA, the OH group of hydroxamic acid moiety in both complexes interacts with heme iron directly with Fe-OH distances of 3.0 and 3.2A respectively. The OH is also hydrogen bonded to His-109 N(epsilon2) and Gln-105N(epsilon2). The plane of benzene ring of ASA is inclined at 70.7 degrees from the plane of heme moiety, whereas the aromatic planes of SHA and BHA are nearly parallel to the heme plane with inclinations of 15.7 and 6.2 degrees , respectively. The mode of ASA binding provides the information about the mechanism of action of aromatic substrates, whereas the binding characteristics of SHA and BHA indicate the mode of inhibitor binding.

  2. Separation of glycols from dilute aqueous solutions via complexation with boronic acids

    Energy Technology Data Exchange (ETDEWEB)

    Randel, L.A.; King, C.J.

    1991-07-01

    This work examines methods of separating low molecular weight glycols from dilute aqueous solution. Extraction into conventional solvents is generally not economical, since, in the literature reviewed, distribution ratios for the two- to four-carbon glycols are all less than one. Distribution ratios can be increased, however, by incorporating into the organic phase an extracting agent that will complex with the solute of interest. The extracting agent investigated in this work is 3-nitrophenylboronic acid (NPBA). NPBA, a boric acid derivative, reversibly complexes with many glycols. The literature on complexation of borate and related compounds with glycols, including mechanistic data, measurement techniques, and applications to separation processes, provides information valuable for designing experiments with NPBA and is reviewed herein. 88 refs., 15 figs., 24 tabs.

  3. Aromatic Amino Acids-Guanidinium Complexes through Cation-π Interactions

    Directory of Open Access Journals (Sweden)

    Cristina Trujillo

    2015-05-01

    Full Text Available Continuing with our interest in the guanidinium group and the different interactions than can establish, we have carried out a theoretical study of the complexes formed by this cation and the aromatic amino acids (phenylalanine, histidine, tryptophan and tyrosine using DFT methods and PCM-water solvation. Both hydrogen bonds and cation-π interactions have been found upon complexation. These interactions have been characterized by means of the analysis of the molecular electron density using the Atoms-in-Molecules approach as well as the orbital interactions using the Natural Bond Orbital methodology. Finally, the effect that the cation-π and hydrogen bond interactions exert on the aromaticity of the corresponding amino acids has been evaluated by calculating the theoretical NICS values, finding that the aromatic character was not heavily modified upon complexation.

  4. Efficiency of membrane technology, activated charcoal, and a micelle-clay complex for removal of the acidic pharmaceutical mefenamic acid.

    Science.gov (United States)

    Khalaf, Samer; Al-Rimawi, Fuad; Khamis, Mustafa; Nir, Shlomo; Bufo, Sabino A; Scrano, Laura; Mecca, Gennaro; Karaman, Rafik

    2013-01-01

    The efficiency of sequential advanced membrane technology wastewater treatment plant towards removal of a widely used non-steroid anti-inflammatory drug (NSAID) mefenamic acid was investigated. The sequential system included activated sludge, ultrafiltration by hollow fibre membranes with 100 kDa cutoff, and spiral wound membranes with 20 kDa cutoff, activated carbon and a reverse osmosis (RO) unit. The performance of the integrated plant showed complete removal of mefenamic acid from spiked wastewater samples. The activated carbon column was the most effective component in removing mefenamic acid with a removal efficiency of 97.2%. Stability study of mefenamic acid in pure water and Al-Quds activated sludge revealed that the anti-inflammatory drug was resistant to degradation in both environments. Batch adsorption of mefenamic acid by activated charcoal and a composite micelle (otadecyltrimethylammonium (ODTMA)-clay (montmorillonite) was determined at 25.0°C. Langmuir isotherm was found to fit the data with Qmax of 90.9 mg g(-1) and 100.0 mg g(-1) for activated carbon and micelle-clay complex, respectively. Filtration experiment by micelle-clay columns mixed with sand in the mg L(-1) range revealed complete removal of the drug with much larger capacity than activated carbon column. The combined results demonstrated that an integration of a micelle-clay column in the plant system has a good potential to improve the removal efficiency of the plant towards NSAID drugs such as mefenamic acid.

  5. Effect of environmental factors on the complexation of iron and humic acid

    Institute of Scientific and Technical Information of China (English)

    Kai Fang; Dongxing Yuan; Lei Zhang; Lifeng Feng; Yaojin Chen; Yuzhou Wang

    2015-01-01

    A method of size exclusion chromatography coupled with ultraviolet spectrophotometry and off-line graphite furnace atomic absorption spectrometry was developed to assess the complexation properties of iron (Fe) and humic acid (HA) in a water environment.The factors affecting the complexation of Fe and HA,such as ionic strength,pH,temperature and UV radiation,were investigated.The Fe-HA complex residence time was also studied.Experimental results showed that pH could influence the deprotonation of HA and hydrolysis of Fe,and thus affected the complexation of Fe and HA.The complexation was greatly disrupted by the presence of NaCl.Temperature had some influence on the complexation.The yield of Fe-HA complexes showed a small decrease at high levels of UV radiation,but the effect of UV radiation on Fe-HA complex formation at natural levels could be neglected.It took about 10 hr for the complexation to reach equilibrium,and the Fe-HA complex residence time was about 20 hr.Complexation of Fe and HA reached a maximum level under the conditions of pH 6,very low ionic strength,in the dark and at a water temperature of about 25℃,for 10 hr.It was suggested that the Fe-HA complex could form mainly in freshwater bodies and reach high levels in the warm season with mild sunlight radiation.With changing environmental parameters,such as at lower temperature in winter or higher pH and ionic strength in an estuary,the concentration of the Fe-HA complex would decrease.

  6. Homodinuclear lanthanide complexes of phenylthiopropionic acid: Synthesis, characterization, cytotoxicity, DNA cleavage, and antimicrobial activity

    Science.gov (United States)

    Shiju, C.; Arish, D.; Kumaresan, S.

    2013-03-01

    Lanthanide complexes of La(III), Pr(III), Nd(III), Sm(III), and Ho(III) with phenylthiopropionic acid were synthesized and characterized by elemental analysis, mass, IR, electronic spectra, molar conductance, TGA, and powder XRD. The results show that the lanthanide complexes are homodinuclear in nature. The two lanthanide ions are bridged by eight oxygen atoms from four carboxylate groups. Thermal decomposition profiles are consistent with the proposed formulations. Powder XRD studies show that all the complexes are amorphous in nature. Antimicrobial studies indicate that these complexes exhibit more activity than the ligand itself. The DNA cleavage activity of the ligand and its complexes were assayed on Escherichia coli DNA using gel electrophoresis in the presence of H2O2. The result shows that the Pr(III) and Nd(III) complexes have completely cleaved the DNA. The anticancer activities of the complexes have also been studied towards human cervical cancer cell line (HeLa) and colon cancer cells (HCT116) and it was found that the La(III) and Nd(III) complexes are more active than the corresponding Pr(III), Sm(III), Ho(III) complexes, and the free ligand on both the cancer cells.

  7. Oleic acid is a key cytotoxic component of HAMLET-like complexes.

    Science.gov (United States)

    Permyakov, Sergei E; Knyazeva, Ekaterina L; Khasanova, Leysan M; Fadeev, Roman S; Zhadan, Andrei P; Roche-Hakansson, Hazeline; Håkansson, Anders P; Akatov, Vladimir S; Permyakov, Eugene A

    2012-01-01

    HAMLET is a complex of α-lactalbumin (α-LA) with oleic acid (OA) that selectively kills tumor cells and Streptococcus pneumoniae. To assess the contribution of the proteinaceous component to cytotoxicity of HAMLET, OA complexes with proteins structurally and functionally distinct from α-LA were prepared. Similar to HAMLET, the OA complexes with bovine β-lactoglobulin (bLG) and pike parvalbumin (pPA) (bLG-OA-45 and pPA-OA-45, respectively) induced S. pneumoniae D39 cell death. The activation mechanisms of S. pneumoniae death for these complexes were analogous to those for HAMLET, and the cytotoxicity of the complexes increased with OA content in the preparations. The half-maximal inhibitory concentration for HEp-2 cells linearly decreased with rise in OA content in the preparations, and OA concentration in the preparations causing HEp-2 cell death was close to the cytotoxicity of OA alone. Hence, the cytotoxic action of these complexes against HEp-2 cells is induced mostly by OA. Thermal stabilization of bLG upon association with OA implies that cytotoxicity of bLG-OA-45 complex cannot be ascribed to molten globule-like conformation of the protein component. Overall, the proteinaceous component of HAMLET-like complexes studied is not a prerequisite for their activity; the cytotoxicity of these complexes is mostly due to the action of OA.

  8. Synthesis, characterization, cytotoxicity, DNA cleavage and antimicrobial activity of homodinuclear lanthanide complexes of phenylthioacetic acid

    Institute of Scientific and Technical Information of China (English)

    T. F. Abbs Fen Reji; A. Jeena Pearl; Bojaxa A. Rosy

    2013-01-01

    Lanthanide complexes of Eu(III), Gd(III), Nd(III), Sm(III), and Tb(III) with phenylthioacetic acid were synthesized and characterized by elemental analysis, mass, infrared radiation (IR), electronic spectra, molar conductance, thermogravimetric analysis (TGA), and powder X-ray diffraction (XRD). The results showed that the lanthanide complexes were homodinuclear in nature. The two lanthanide ions were bridged by eight oxygen atoms from four carboxylate groups. Thermal decomposition profiles were consis-tent with the proposed formulations. Powder XRD studies showed that all the complexes were amorphous in nature. Antimicrobial studies indicated that these complexes exhibited more activity than the ligand itself. The DNA cleavage activity of the ligand and its complexes were assayed on CT DNA using gel electrophoresis in the presence of H2O2. The result showed that the Eu(III) and Nd(III) complexes completely cleaved the DNA. The anticancer activities of the complexes were also studied towards human cervical cancer cell line (HeLa) and colon cancer cells (HCT116) and it was found that the Eu(III) and Nd(III) complexes were more active than the corresponding Gd(III), Sm(III), Tb(III) complexes and the free ligand on both the cancer cells.

  9. Forward osmosis for oily wastewater reclamation: Multi-charged oxalic acid complexes as draw solutes

    KAUST Repository

    Ge, Qingchun

    2017-06-11

    Forward osmosis (FO) has demonstrated its merits in hybrid FO seawater desalination. However, FO may have a potential for other applications if suitable draw solutes are available. In this study, a series of novel draw solutes based on oxalic acid (OA)-transitional metal complexes are presented. Influential factors of FO performance have been systematically investigated by varying the transitional metals, cations of the complex draw solutes as well as the experimental conditions. Compared to NaCl and other recently synthesized draw solutes, the OA complexes show superior FO performance in terms of high water fluxes up to 27.5 and 89.1 LMH under the respective FO and PRO (pressure retarded osmosis) modes, both with negligible reverse solute fluxes. The features of octahedral geometry, abundant hydrophilic groups and ionic species are crucial for the OA complexes as appropriate draw solutes with satisfactory FO performance. Among the synthesized OA complexes, the ammonium salt of chromic complex (NH4-Cr-OA) outperforms others due to the presence of more ionic species in its complex system. NH4-Cr-OA also performs better than the typical NaCl draw solute in FO oily wastewater treatment with higher water recovery and negligible reverse fluxes. Dilute solutions of OA complexes have been reconcentrated through membrane distillation (MD) and reused to new round of FO processes. The OA complexes have demonstrated their suitability and superiority as a novel class of draw solutes for the FO process in this study.

  10. Homodinuclear lanthanide complexes of phenylthiopropionic acid: synthesis, characterization, cytotoxicity, DNA cleavage, and antimicrobial activity.

    Science.gov (United States)

    Shiju, C; Arish, D; Kumaresan, S

    2013-03-15

    Lanthanide complexes of La(III), Pr(III), Nd(III), Sm(III), and Ho(III) with phenylthiopropionic acid were synthesized and characterized by elemental analysis, mass, IR, electronic spectra, molar conductance, TGA, and powder XRD. The results show that the lanthanide complexes are homodinuclear in nature. The two lanthanide ions are bridged by eight oxygen atoms from four carboxylate groups. Thermal decomposition profiles are consistent with the proposed formulations. Powder XRD studies show that all the complexes are amorphous in nature. Antimicrobial studies indicate that these complexes exhibit more activity than the ligand itself. The DNA cleavage activity of the ligand and its complexes were assayed on Escherichia coli DNA using gel electrophoresis in the presence of H(2)O(2). The result shows that the Pr(III) and Nd(III) complexes have completely cleaved the DNA. The anticancer activities of the complexes have also been studied towards human cervical cancer cell line (HeLa) and colon cancer cells (HCT116) and it was found that the La(III) and Nd(III) complexes are more active than the corresponding Pr(III), Sm(III), Ho(III) complexes, and the free ligand on both the cancer cells.

  11. Antibacterial, Prooxidative and Genotoxic Activities of Gallic Acid and its Copper and Iron Complexes against Escherichia coli

    Directory of Open Access Journals (Sweden)

    JONATHAN M. BARCELO

    2014-12-01

    Full Text Available In this study, gallic acid and its complexes with aluminum and iron were investigated for their antibacterial, pro-oxidative, and genotoxic properties at alkaline pH. At 4.0μmol/mL, gallic acid displayed bacteriostatic property while aluminum-gallic acid and iron-gallic acid complexes showed bactericidal property against Escherichia coli ATCC 25922. A higher antibacterial activity was observed in the turbidimetric assay compared to the well-diffusion assay. The metal complexes of gallic acid also generated a higher concentration of malondialdehyde and hydrogen peroxide compared to gallic acid alone at > 0.50µmol/mL. Using the SOS response of the DNA repair-deficient Escherichia coli PQ37, the metal complexes of gallic acid resulted to a significantly higher SOS Induction Factors (ρ<0.01 at ≥0.25μmol/mL. In addition, gallic acid and its metal complexes decrease the cell surface hydrophobicity of E. coli ATCC 25922 in a dose-dependent manner. The present study suggests that the antibacterial property of gallic acid and its metal complexes against Escherichia coli was caused by its pro-oxidative and genotoxic properties. Since metals are involved in the synthesis of the metal complexes of gallic acid, further tests should be conducted to determine their stability and effects to human health.

  12. Cooperative Catalysis of Combined Systems of Transition-Metal Complexes with Lewis Acids: Theoretical Understanding.

    Science.gov (United States)

    Guan, Wei; Zeng, Guixiang; Kameo, Hajime; Nakao, Yoshiaki; Sakaki, Shigeyoshi

    2016-10-01

    The combination of transition-metal complexes and Lewis acids has been recently applied to several catalytic reactions, in which the Lewis acid plays a crucial role as a non-innocent additive to accelerate the reaction. In this review article, the reasons for the acceleration by the Lewis acid are discussed based on our recent theoretical studies. In the H-H σ-bond activation of a dihydrogen molecule by a nickel(0)-borane complex, the empty p orbital of the borane moiety interacts with the H-H σ bonding MO to form charge transfer (CT) from the dihydrogen molecule to the borane moiety to accelerate the reaction. In the B-F σ-bond activation of BF3 by a platinum(0)-bisphosphine complex, the second BF3 molecule interacts with the F atom that is dissociating from the B atom to stabilize the transition state and product by the CT from the F atom to the second BF3 . In this reaction, the substrate BF3 plays a crucial role as the Lewis acid to accelerate the activation of the B-F σ bond. In the nickel-catalyzed decyanative coupling of arylcarboxybenzonitriles with acetylenes, two molecules of the aluminum Lewis acid interact with the cyano N atom and the carbonyl O atom of the substrate to stabilize the transition state and intermediate. In the nickel-catalyzed alkylation of aromatic amides with alkenes, the Lewis acid enhances the para regioselectivity of alkylation by interacting with the carbonyl O atom. In the nickel-catalyzed carboxylation of sp(3) carbon and sp carbon atoms with carbon dioxide, not the σ-bond activation but the insertion reaction of carbon dioxide into the metal-carbon bond is accelerated by the Lewis acid by interacting with the O atom of carbon dioxide, because the CT from the metal-carbon bond to carbon dioxide is enhanced by the interaction. This theoretical knowledge suggests that the combination of transition-metal complex and Lewis acid can broaden the application range of transition-metal complex as catalyst. © 2016 The Chemical

  13. A relativistic density functional study of uranyl hydrolysis and complexation by carboxylic acids in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Rupashree Shyama

    2009-02-10

    In this work, the complexation of uranium in its most stable oxidation state VI in aqueous solution was studied computationally, within the framework of density functional (DF) theory. The thesis is divided into the following parts: Chapter 2 briefly summarizes the relevant general aspects of actinide chemistry and then focuses on actinide environmental chemistry. Experimental results on hydrolysis, actinide complexation by carboxylic acids, and humic substances are presented to establish a background for the subsequent discussion. Chapter 3 describes the computational method used in this work and the relevant features of the parallel quantum chemistry code PARAGAUSS employed. First, the most relevant basics of the applied density functional approach are presented focusing on relativistic effects. Then, the treatment of solvent effects, essential for an adequate modeling of actinide species in aqueous solution, will be introduced. At the end of this chapter, computational parameters and procedures will be summarized. Chapter 4 presents the computational results including a comparison to available experimental data. In the beginning, the mononuclear hydrolysis product of UO{sub 2}{sup 2+}, [UO{sub 2}OH]{sup +}, will be discussed. The second part deals with actinide complexation by carboxylate ligands. First of all the coordination number for uranylacetate will be discussed with respect to implications for the complexation of actinides by humic substances followed by the uranyl complexation of aromatic carboxylic acids in comparison to earlier results for aliphatic ones. In the end, the ternary uranyl-hydroxo-acetate are discussed, as models of uranyl humate complexation at ambient condition.

  14. Effects of Lanthanum-Amino Acid Complexes on Egg Hatching and Nauplius Metamorphosis of Penaeus chinensis

    Institute of Scientific and Technical Information of China (English)

    Xin Fuyan; Qu Keming

    2002-01-01

    Studies have been carried out on the effect of lanthanum-amino acid complexes on embryo development and nauplius growth ofPenaeus chinensis. The experimental results indicate that: (1)The optimum concentrations of lanthanum-proline and Lanthanumphenylalanine for the development of eggs in monocell and dicell stages are 1.50~ 4.00mg/L and 0.50~3.00 mg/L, respectively, the egg hatching rates being raised by 21.0 ~ 46.0% and 23.0 ~42.8% ( P < 0.05 ) respectively. (2)The optimum concentrations of lanthanum- proline complex and Lanthanum-phenylalanine complex for the growth ofnauplii are 1.50~4.00 mg/L and 0.50~3.00 mg/L, the metamorphosis rate from nauplius to protozoea being raised by 16.4 ~27.5% and 20.4~26.7% (P < 0.05 ) respectively. (3)The positive effect of lanthanum-amino acid complexes on egg hatching and nauplius metamorphosis of Penaeus chinensis is better than that of lanthanum. With regard to the positive effect, lanthanum-proline complex is better than Lanthanum-phenylalanine complex.

  15. Luminescence properties of polymers containing europium complexes with 4-tert-butylbenzoic acid

    Institute of Scientific and Technical Information of China (English)

    林美娟; 王小萍; 唐强; 凌启淡

    2013-01-01

    The binary europium complex EuL3 (L=4-tert-butylbenzoate) and ternary europium complexes EuL3TTA0.1 (TTA=2-thenoyltrifluoroacetone), EuL3DBM0.5 (DBM=dibenzoylmethane) and EuL3phen0.5 (phen=1, 10-phenanthroline) were synthesized. The poly(methyl methacrylate) (PMMA) or copolymer of methyl methacrylate (MMA) with acrylic acid (AA) composites doped with europium complexes were prepared by radical in-situ polymerization. The influences of the europium complexes, ligands, N,N-dimethylformamide (DMF) and monomers on the luminescence properties of the doped polymers were investigated. The results showed that the fluorescence excitation bands of binary and ternary complexes were in accordance with their ultraviolet absorption bands. All the complexes and the doped polymer composites exhibited the ligand-sensitized red characteristic emission of Eu3+ion. The fluorescence intensity of the polymer composites increased in the sequence of EuL3/PMMAacid comonomer decreased the lumi-nescence intensity of the polymer composites.

  16. Investigation on the syntheses and structures of YIII complexes with aminopolycarboxylic acids (IV)

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper deals with the structure of the YIII complex with aminopolycarboxylic acids, synthesis and structural determination of the complex (NH4)[YIII(edta)(H2O)3]3H2O (edta = ethylenediaminetetraacetic acid). The crystal and molecular structures of the (NH4)[YIII(edta)(H2O)3]3H2O complex have been determined by single-crystal X-ray structure analysis. The crystal of the complex (NH4)[YIII(edta)(H2O)3]3H2O belongs to orthorhombic crystal system and fdd2 space group. The crystal data are as follows: a = 1.944 1(9) nm, b = 3.545 9(18) nm, c = 1.219 6(6) nm, V = 8.407(7) nm3, Z = 16, Mr = 503.25, Dc = 1.590 gcm 3,  = 2.844 mm 1 and F(000) = 4 160. The final R and Rw are 0.048 6 and 0.133 2 for 3 388 (I>2 (I)) unique reflections, respectively. The complex anion [YIII(edta)(H2O)3]  has a pseudo-monocapped square antiprismatic nine-coordinate structure in which the six coordinate atoms (two N and four O) are from an edta ligand and three water molecules coordinate to the central YIII ion directly. From the results it can be predicted that the YIII ion can also form a nine-coordinate complex with ttha (=triethylenetetraminehexaacetic acid) ligand, so the radioactive complex anion [90YIII(Httha)]2  can supply a free carboxyl group ( CH2COOH) being used for molecular embellishment to form the TDDS for the treatment of cancers.

  17. Fluorescence and Judd-Ofelt analysis of rare earth complexes with maleic anhydride and acrylic acid

    Institute of Scientific and Technical Information of China (English)

    WEN Shipeng; ZHANG Xiaoping; HU Shui; ZHANG Liqun; LIU Li

    2008-01-01

    Two kinds of Eu-complexes, Eu(TTA)2(Phen)(AA) and Eu(TTA)2(Phen)(MA) (HTFA=2-Thenoyltrifluoroacetone, Phen=1,10-phenanthroline, AA=acrylic acid, MA=Maleic anhydride), which combined the excellent fluorescence properties of Eu(TTA)2(Phen)(H2O) and the reactivity of acrylic acid and maleic anhydride with radicals, were synthesized. The two complexes were characterized by elemental analysis, infrared (IR) spectra, and X-ray photoelectron spectroscopy (XPS). Based on the data shown from the fluorescent spectra of the Eu-MA and Eu-AA complexes, the Ωλ (λ=2 and 4) experimental intensity parameters were calculated. The results demonstrated that the Ω2 intensity parameters for the two complexes were smaller than those for the Eu(TTA)2(Phen)(H2O) complex, indicating that a less symmetri-cal chemical environment existed in the complexes. It implied that the radiative efficiency of the 5D0 of these two complexes could be en-hanced by ligand of MA and AA, respectively. The luminescent lifetime of the Eu-AA (τ=7.26×10-4 s) or Eu-MA complex (τ=-8.12×10-4 s) was higher than that of the Eu(TTA)2(Phen)(H2O) complex, which was attributed to the substitution of the water molecule (H2O) in Eu(TTA)2(Phen)(H2O) by the MA or AA ligand.

  18. Hydrogen Isotopes in Amino Acids and Soils Offer New Potential to Study Complex Processes

    Science.gov (United States)

    Fogel, M. L.; Newsome, S. D.; Williams, E. K.; Bradley, C. J.; Griffin, P.; Nakamoto, B. J.

    2016-12-01

    Hydrogen isotopes have been analyzed extensively in the earth and biogeosciences to trace water through various environmental systems. The majority of the measurements have been made on water in rocks and minerals (inorganic) or non-exchangeable H in lipids (organic), important biomarkers that represent a small fraction of the organic molecules synthesized by living organisms. Our lab has been investigating hydrogen isotopes in amino acids and complex soil organic matter, which have traditionally been thought to be too complex to interpret owing to complications from potentially exchangeable hydrogen. For the amino acids, we show how hydrogen in amino acids originates from two sources, food and water, and demonstrate that hydrogen isotopes can be routed directly between organisms. Amino acid hydrogen isotopes may unravel cycling in extremophiles in order to discover novel biochemical pathways central to the organism. For soil organic matter, recent approaches to understanding the origin of soil organic matter are pointing towards root exudates along with microbial biomass as the source, rather than aboveground leaf litter. Having an isotope tracer in very complex, potentially exchangeable organic matter can be handled with careful experimentation. Although no new instrumentation is being used per se, extension of classes of organic matter to isotope measurements has potential to open up new doors for understanding organic matter cycling on earth and in planetary materials.

  19. Biophysical and structural characterisation of nucleic acid complexes with modified cyclodextrins using circular dichroism.

    Science.gov (United States)

    O'Mahony, Aoife M; Cronin, Michael F; McMahon, Anthony; Evans, James C; Daly, Kathleen; Darcy, Raphael; O'Driscoll, Caitriona M

    2014-05-01

    Modified cyclodextrins (CDs) have shown great promise as non-viral gene and siRNA delivery vectors in a range of in vitro and in vivo studies. In the current study, structural and biophysical characterisation of selected CDs was carried out to enhance our understanding of their interaction with nucleic acids. The methods used for such characterisation were dynamic light scattering, zeta potential measurements and circular dichroism. Variations in the chemistries of individual CDs and in the type of formulation were shown to affect key properties of complexes such as size, surface charge and nucleic acid conformation. Furthermore, the effects of temperature and pH on the conformation of nucleic acids were investigated. pH studies were intended to mimic the conditions encountered by cationic complexes during endocytosis. Circular dichroism studies revealed that changes occurred in DNA and siRNA conformation upon complexation with CDs and when exposed to increasing temperature and decreasing pH. Overall, siRNA appeared to be more susceptible to conformational changes although complexation of siRNA with CDs tended to have a stabilising effect. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  20. Sunlight-initiated chemistry of aqueous pyruvic acid: building complexity in the origin of life.

    Science.gov (United States)

    Griffith, Elizabeth C; Shoemaker, Richard K; Vaida, Veronica

    2013-10-01

    Coupling chemical reactions to an energy source is a necessary step in the origin of life. Here, we utilize UV photons provided by a simulated sun to activate aqueous pyruvic acid and subsequently prompt chemical reactions mimicking some of the functions of modern metabolism. Pyruvic acid is interesting in a prebiotic context due to its prevalence in modern metabolism and its abiotic availability on early Earth. Here, pyruvic acid (CH3COCOOH, a C3 molecule) photochemically reacts to produce more complex molecules containing four or more carbon atoms. Acetoin (CH3CHOHCOCH3), a C4 molecule and a modern bacterial metabolite, is produced in this chemistry as well as lactic acid (CH3CHOHCOOH), a molecule which, when coupled with other abiotic chemical reaction pathways, can provide a regeneration pathway for pyruvic acid. This chemistry is discussed in the context of plausible environments on early Earth such as near the ocean surface and atmospheric aerosol particles. These environments allow for combination and exchange of reactants and products of other reaction environments (such as shallow hydrothermal vents). The result could be a contribution to the steady increase in chemical complexity requisite in the origin of life.

  1. [Molluscacide activity of a mixture of 6-n-alkyl salicylic acids (anacardic acid) and 2 of its complexes with copper (II) and lead (II)].

    Science.gov (United States)

    Mendes, N M; de Oliveira, A B; Guimarães, J E; Pereira, J P; Katz, N

    1990-01-01

    The molluscicide activity of hexanic extract from Anacardium occidentale L. (cashew) nut shell, of copper (II) complex, of lead (II) complex and anacardic acid has been compared in the laboratory in an attempt to obtain better stability than anacardic acid. This was obtained from the hexanic extract of the cashew nut shell by precipitation with lead (II) hydroxide or cupric sulfate plus sodium hydroxide or (II) cupric hydroxide followed by treatment of lead (II) complex with a diluted solution of sulfuric acid. Ten products of the mixture obtained were tested on adults snails of Biomphalaria glabrata at 1 to 10 ppm. The most active products were copper (II) complex, obtained by cupric sulfate plus sodium hydroxide, and anacardic acid (sodium hydroxide) which presented activity at 4 ppm. The anacardic acid's lead content was above the limits accepted by the United States standards.

  2. Fluorescence Properties of Eu3+/Gd3+/Citric Acid Mixed Complexes Doping in Silicon Rubber Matrix

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Series of doped rare earth complexes-EuxGd(1-x)(CA)3·nH2O (CA=citric acid) were synthesized. Some characterizations were taken for these complexes. The experimental results shows that the doped rare earth complexes have the best fluorescence property when the ratio of Eu and Gd is from 0.7 to 0.3. Silicon rubber-based composites were prepared by mechanical blending the EuxGd(1-x)(CA)3·nH2O and silicon rubber. Then, the fluorescent property of the composites was studied. It is found that the fluorescence intensity of the composites increase linearly with the contents of the rare earth complexes increasing.

  3. Fractionation of SWNT/nucleic acid complexes by agarose gel electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Vetcher, Alexandre A [Institute of Biomedical Sciences and Technology and Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, TX 75083 (United States); Srinivasan, Srimeenakshi [Institute of Biomedical Sciences and Technology and Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, TX 75083 (United States); Vetcher, Ivan A [Institute of Biomedical Sciences and Technology and Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, TX 75083 (United States); Abramov, Semen M [NanoTech Institute, University of Texas at Dallas, Richardson, TX 75083 (United States); Kozlov, Mikhail [NanoTech Institute, University of Texas at Dallas, Richardson, TX 75083 (United States); Baughman, Ray H [NanoTech Institute, University of Texas at Dallas, Richardson, TX 75083 (United States); Levene, Stephen D [Institute of Biomedical Sciences and Technology and Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, TX 75083 (United States)

    2006-08-28

    We show that aqueous dispersions of single-walled carbon nanotubes (SWNTs), prepared with the aid of nucleic acids (NAs) such as RNA or DNA, can be separated into fractions using agarose gel electrophoresis. In a DC electric field, SWNT/NA complexes migrate in the gel in the direction of positive potential to form well-defined bands. Raman spectroscopy as a function of band position shows that nanotubes having different spectroscopic properties possess different electrophoretic mobilities. The migration patterns for SWNT/RNA and SWNT/DNA complexes differ. Parallel elution of the SWNT/NA complexes from the gel during electrophoresis and subsequent characterization by AFM reveals differences in nanotube diameter, length and curvature. The results suggest that fractionation of nanotubes can be achieved by this procedure. We discuss factors affecting the mobility of the nanotube complexes and propose analytical applications of this technique.

  4. Fractionation of SWNT/nucleic acid complexes by agarose gel electrophoresis.

    Science.gov (United States)

    Vetcher, Alexandre A; Srinivasan, Srimeenakshi; Vetcher, Ivan A; Abramov, Semen M; Kozlov, Mikhail; Baughman, Ray H; Levene, Stephen D

    2006-08-28

    We show that aqueous dispersions of single-walled carbon nanotubes (SWNTs), prepared with the aid of nucleic acids (NAs) such as RNA or DNA, can be separated into fractions using agarose gel electrophoresis. In a DC electric field, SWNT/NA complexes migrate in the gel in the direction of positive potential to form well-defined bands. Raman spectroscopy as a function of band position shows that nanotubes having different spectroscopic properties possess different electrophoretic mobilities. The migration patterns for SWNT/RNA and SWNT/DNA complexes differ. Parallel elution of the SWNT/NA complexes from the gel during electrophoresis and subsequent characterization by AFM reveals differences in nanotube diameter, length and curvature. The results suggest that fractionation of nanotubes can be achieved by this procedure. We discuss factors affecting the mobility of the nanotube complexes and propose analytical applications of this technique.

  5. Fractionation of SWNT/nucleic acid complexes by agarose gel electrophoresis

    Science.gov (United States)

    Vetcher, Alexandre A.; Srinivasan, Srimeenakshi; Vetcher, Ivan A.; Abramov, Semen M.; Kozlov, Mikhail; Baughman, Ray H.; Levene, Stephen D.

    2006-08-01

    We show that aqueous dispersions of single-walled carbon nanotubes (SWNTs), prepared with the aid of nucleic acids (NAs) such as RNA or DNA, can be separated into fractions using agarose gel electrophoresis. In a DC electric field, SWNT/NA complexes migrate in the gel in the direction of positive potential to form well-defined bands. Raman spectroscopy as a function of band position shows that nanotubes having different spectroscopic properties possess different electrophoretic mobilities. The migration patterns for SWNT/RNA and SWNT/DNA complexes differ. Parallel elution of the SWNT/NA complexes from the gel during electrophoresis and subsequent characterization by AFM reveals differences in nanotube diameter, length and curvature. The results suggest that fractionation of nanotubes can be achieved by this procedure. We discuss factors affecting the mobility of the nanotube complexes and propose analytical applications of this technique.

  6. A novel DTPA cross-linking of hyaluronic acid and metal complexation thereof.

    Science.gov (United States)

    Buffa, Radovan; Běťák, Jiří; Kettou, Sofiane; Hermannová, Martina; Pospíšilová, Lucie; Velebný, Vladimír

    2011-09-27

    Macromolecular conjugates of a natural polysaccharide, hyaluronic acid, with diethylenetriaminepentaacetic acid (DTPA)-metal complexes were synthesized and characterized by FTIR, NMR, SEC-MALLS and ICP analysis. Several parameters of the cross-linking reaction as molecular weight of starting HA, temperature, equivalent of DTPA bis-anhydride, concentration of HA, presence of transacylation catalyst DMAP and reaction time were studied. The mechanism for the reaction was suggested and relationship between the molecular weight assigned by SEC-MALLS, reaction parameters and rheological properties of the final cross-linked products were investigated. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. Potentiometric studies on ternary complexes involving some divalent transition metal ions, gallic acid and biologically abundant aliphatic dicarboxylic acids in aqueous solutions

    Directory of Open Access Journals (Sweden)

    Abdelatty Mohamed Radalla

    2015-06-01

    Full Text Available Formation of binary and ternary complexes of the divalent transition metal ions, Cu2+, Ni2+, Co2+ and Zn2+ with gallic acid and the biologically important aliphatic dicarboxylic acids (adipic, succinic, malic, malonic, maleic, tartaric and oxalic acids were investigated by means of the potentiometric technique at 25 °C and I = 0.10 mol dm−3 NaNO3. The acid-base properties of the ligands were investigated and discussed. The acidity constants of gallic acid and aliphatic dicarboxylic acids were determined and used for determining the stability constants of the binary and ternary complexes formed in the aqueous medium under the above experimental conditions. The formation of the different 1:1 and 1:2 binary complexes and 1:1:1 ternary complexes are inferred from the corresponding potentiometric pH-metric titration curves. The ternary complex formation was found to occur in a stepwise manner. The stability constants of these binary and ternary systems were calculated. The values of Δ log K, percentage of relative stabilization (%R.S. and log X were evaluated and discussed. The concentration distribution of the various complex species formed in solution was evaluated and discussed. The mode of chelation of ternary complexes formed was ascertained by conductivity measurements.

  8. Base-Free Production of H-2 by Dehydrogenation of Formic Acid Using An Iridium-bisMETAMORPhos Complex

    NARCIS (Netherlands)

    Oldenhof, S.; de Bruin, B.; Lutz, M.; Siegler, M.A.; Patureau, F.W.; van der Vlugt, J.I.; Reek, J.N.H.

    2013-01-01

    An iridium complex based on a cooperative ligand that functions as an internal base is reported. This complex can rapidly and cleanly dehydrogenate formic acid in absence of external base, a reaction that is required if formic acid is to be exploited as an energy carrier (see scheme).

  9. Biosynthesis of caffeic acid in Escherichia coli using its endogenous hydroxylase complex

    Directory of Open Access Journals (Sweden)

    Lin Yuheng

    2012-04-01

    Full Text Available Abstract Background Caffeic acid (3,4-dihydroxycinnamic acid is a natural phenolic compound derived from the plant phenylpropanoid pathway. Caffeic acid and its phenethyl ester (CAPE have attracted increasing attention for their various pharmaceutical properties and health-promoting effects. Nowadays, large-scale production of drugs or drug precursors via microbial approaches provides a promising alternative to chemical synthesis and extraction from plant sources. Results We first identified that an Escherichia coli native hydroxylase complex previously characterized as the 4-hydroxyphenylacetate 3-hydroxylase (4HPA3H was able to convert p-coumaric acid to caffeic acid efficiently. This critical enzymatic step catalyzed in plants by a membrane-associated cytochrome P450 enzyme, p-coumarate 3-hydroxylase (C3H, is difficult to be functionally expressed in prokaryotic systems. Moreover, the performances of two tyrosine ammonia lyases (TALs from Rhodobacter species were compared after overexpression in E. coli. The results indicated that the TAL from R. capsulatus (Rc possesses higher activity towards both tyrosine and L-dopa. Based on these findings, we further designed a dual pathway leading from tyrosine to caffeic acid consisting of the enzymes 4HPA3H and RcTAL. This heterologous pathway extended E. coli native tyrosine biosynthesis machinery and was able to produce caffeic acid (12.1 mg/L in minimal salt medium. Further improvement in production was accomplished by boosting tyrosine biosynthesis in E. coli, which involved the alleviation of tyrosine-induced feedback inhibition and carbon flux redirection. Finally, the titer of caffeic acid reached 50.2 mg/L in shake flasks after 48-hour cultivation. Conclusion We have successfully established a novel pathway and constructed an E. coli strain for the production of caffeic acid. This work forms a basis for further improvement in production, as well as opens the possibility of microbial synthesis

  10. Effect of fatty acids complexed with polyethyleneimine on the flow curves of TiO2 nanoparticle/toluene suspensions

    OpenAIRE

    Motoyuki Iijima; Yasuhiro Kawaharada; Junichi Tatami

    2016-01-01

    A series of polyethyleneimine (PEI)–fatty acid complexes using oleic acid (OA), isostearic acid (ISA), and stearic acid (SA) were prepared through a simple process. While PEI was not soluble in toluene, the complex with OA and ISA became soluble when its additive content was greater than 5 mol% based on the ethyleneimine (EI) unit of PEI. PEI–SA had similar solubility in toluene when more than 5 mol% of SA was added; however, the complex precipitated when the additive ratio of SA was increase...

  11. Spectroscopy of charge transfer complexes of four amino acids as organic two-dimensional conductors

    Energy Technology Data Exchange (ETDEWEB)

    Padhiyar, Ashvin; Patel, A J; Oza, A T [Department of Physics, Sardar Patel University, Vallabh Vidyanagar-388 120, Gujarat (India)

    2007-12-05

    It is found in this study that four amino acids, namely asparagine, arginine, histidine and glutamine form two-dimensional conducting systems which are charge transfer complexes (CTCs) with organic acceptors like TCNQ, TCNE, chloranil, DDQ, TNF and iodine. It is verified using optical absorption edges that these are 2d conductors like transition metal dichalcogenides obeying absorption functions different from 1d and 3d conductors. This 2d nature is related to the network of intermolecular H-bonding in these complexes, which leads to a global H-bonded network resulting in the absence of local deformation due to the relaxation of strain.

  12. Spectroscopy of charge transfer complexes of four amino acids as organic two-dimensional conductors

    Science.gov (United States)

    Padhiyar, Ashvin; Patel, A. J.; Oza, A. T.

    2007-12-01

    It is found in this study that four amino acids, namely asparagine, arginine, histidine and glutamine form two-dimensional conducting systems which are charge transfer complexes (CTCs) with organic acceptors like TCNQ, TCNE, chloranil, DDQ, TNF and iodine. It is verified using optical absorption edges that these are 2d conductors like transition metal dichalcogenides obeying absorption functions different from 1d and 3d conductors. This 2d nature is related to the network of intermolecular H-bonding in these complexes, which leads to a global H-bonded network resulting in the absence of local deformation due to the relaxation of strain.

  13. A New Complex with Good Catalytic Properties in Asymmetric Synthesis of Cyclopropanecarboxylic Acids

    Institute of Scientific and Technical Information of China (English)

    CAI Ya; ZHENG He-Gen; XIN Xin-Quan

    2003-01-01

    @@ The chemistry of transition metal-sulfur clusters has attracted much attention recently owing to their relevance to certain biological and industrial catalyses, rich structural chemistry, and special reactive properties as well as potential application in nonlinear optical materials. [1~ 3] In this article, a new complex, WCu2S4 (dppf)2 [ dppf = 1, 1′bis(diphenylphosphino)ferrocene] was synthesized through solid state reaction, and it was found that this complex had good catalytic properties in asymmetric synthesis of cyclopropanecarboxylic acids.

  14. A Complex Prime Numerical Representation of Amino Acids for Protein Function Comparison.

    Science.gov (United States)

    Chen, Duo; Wang, Jiasong; Yan, Ming; Bao, Forrest Sheng

    2016-08-01

    Computationally assessing the functional similarity between proteins is an important task of bioinformatics research. It can help molecular biologists transfer knowledge on certain proteins to others and hence reduce the amount of tedious and costly benchwork. Representation of amino acids, the building blocks of proteins, plays an important role in achieving this goal. Compared with symbolic representation, representing amino acids numerically can expand our ability to analyze proteins, including comparing the functional similarity of them. Among the state-of-the-art methods, electro-ion interaction pseudopotential (EIIP) is widely adopted for the numerical representation of amino acids. However, it could suffer from degeneracy that two different amino acid sequences have the same numerical representation, due to the design of EIIP. In light of this challenge, we propose a complex prime numerical representation (CPNR) of amino acids, inspired by the similarity between a pattern among prime numbers and the number of codons of amino acids. To empirically assess the effectiveness of the proposed method, we compare CPNR against EIIP. Experimental results demonstrate that the proposed method CPNR always achieves better performance than EIIP. We also develop a framework to combine the advantages of CPNR and EIIP, which enables us to improve the performance and study the unique characteristics of different representations.

  15. Heterobimetallic dinuclear lanthanide alkoxide complexes as acid-base difunctional catalysts for transesterification.

    Science.gov (United States)

    Zeng, Ruijie; Sheng, Hongting; Zhang, Yongcang; Feng, Yan; Chen, Zhi; Wang, Junfeng; Chen, Man; Zhu, Manzhou; Guo, Qingxiang

    2014-10-03

    A practical lanthanide(III)-catalyzed transesterification of carboxylic esters, weakly reactive carbonates, and much less-reactive ethyl silicate with primary and secondary alcohols was developed. Heterobimetallic dinuclear lanthanide alkoxide complexes [Ln2Na8{(OCH2CH2NMe2)}12(OH)2] (Ln = Nd (I), Sm (II), and Yb (III)) were used as highly active catalysts for this reaction. The mild reaction conditions enabled the transesterification of various substrates to proceed in good to high yield. Efficient activation of transesterification may be endowed by the above complexes as cooperative acid-base difunctional catalysts, which is proposed to be responsible for the higher reactivity in comparison with simple acid/base catalysts.

  16. Local solvent acidities in β-cyclodextrin complexes with PRODAN derivatives.

    Science.gov (United States)

    Naughton, Hannah R; Abelt, Christopher J

    2013-03-28

    The local solvent acidities (SA scale) of six 6-carbonyl-2-aminonaphthalene derivatives as β-cyclodextrin complexes in water are determined through fluorescence quenching. The local polarities (E(T)(N) scale) are determined through the shift of the emission center-of-mass. The apparent SA values reflect the solvent structure surrounding the guest’s carbonyl group, whereas the apparent E(T)(N) values reveal the net polarity of the entire guest molecule. Comparison of these values affords greater insight into the structures of the host–guest complexes. Derivatives 1 and 5 show unusually large acidities, indicative of highly exposed carbonyl groups. The remaining compounds give emission intensities pointing to shielded carbonyl groups. In this study, PRODAN and its derivatives are functioning as dual channel sensors of their local environment.

  17. Immune response and disease resistance of calves fed chromium nicotinic acid complex or chromium chloride.

    Science.gov (United States)

    Kegley, E B; Spears, J W; Brown, T T

    1996-07-01

    Twenty-one Holstein bull calves (skinfold thickness after an intradermal injection of phytohemagglutinin were measured to evaluate cell-mediated immune response. Calves supplemented with Cr-nicotinic acid complex had a greater response than did controls at 6, 12, 24, and 48 h after injection. Calves supplemented with CrCl3 had a greater response than did controls at 24 and 48 h after injection. In vitro blastogenic responses of lymphocytes to phytohemagglutinin or pokeweed mitogen and antibody response to porcine red blood cells were not affected by treatment. Following a disease challenge with an intranasal dose of infectious bovine rhinotracheitis on d 75, body temperature tended to be lower for calves supplemented with Cr-nicotinic acid complex than for control calves. Calves supplemented with either Cr source had lower serum cortisol concentrations at 5 d after challenge. Chromium supplementation enhanced cell-mediated immune function.

  18. Thermodynamics of Np(IV) complexes with gluconic acid under alkaline conditions. Sorption studies

    Energy Technology Data Exchange (ETDEWEB)

    Rojo, H.; Garcia-Gutierrez, M.; Missana, T. [CIEMAT, Madrid (Spain). Sorption, Migration and Colloids Lab.; Tits, J.; Wieland, E. [Paul Scherrer Institut, Villigen (Switzerland). Lab. for Waste Management; Gaona, X. [Karlsruhe Institute of Technology, Karlsruhe (Germany). Inst. fuer Nukleare Entsorgung

    2013-05-01

    The complexation of Np(IV) with gluconic acid (GLU) under alkaline conditions was investigated in the absence of Ca by carrying out a series of sorption experiments. The decrease of Np(IV) sorption on the sorbing material at increasing concentrations of GLU was interpreted as the formation of Np(IV)-GLU aqueous complexes. The modelling of experimental data according to the Schubert method [1] confirmed the formation of a complex with a Np:GLU ratio 1: 1. The stoichiometry of the complex Np(OH){sub 4}GLU{sup -} was proposed based on the experimental observation that no proton exchange occurred during the course of the complexation reaction and that Np(OH){sub 4}(aq) was the predominant hydrolysis product in the absence of GLU. A log *{beta}{sup 0}{sub 1,4,1} = -2.92 {+-} 0.30 for the formation reaction Np{sup 4+} + 4H{sub 2}O + GLU{sup -} <=> Np(OH){sub 4}GLU{sup -} + 4H{sup +} was calculated based on the conditional stability constants determined from sorption experiments and using the Np(IV) thermodynamic data selected in the NEA reviews [2]. Linear free energy relationships (LFER) confirmed that the stoichiometry and stability of the Np(IV)-GLU complex characterized in this work are consistent with data available for Th(IV)-, U(IV)- and Pu(IV)-GLU complexes. (orig.)

  19. Antitumor activity of a 2-pyridinecarboxaldehyde 2-pyridinecarboxylic acid hydrazone copper complex and the related mechanism.

    Science.gov (United States)

    Yang, Yingli; Huang, Tengfei; Zhou, Sufeng; Fu, Yun; Liu, Youxun; Yuan, Yanbin; Zhang, Qiongqing; Li, Shaoshan; Li, Changzheng

    2015-09-01

    In the present study, 2-pyridinecarboxaldehyde 2-pyridinecarboxylic acid hydrazone (PPAH) was prepared and its antitumor activity was evaluated. The inhibition of proliferation of PPAH against the HepG2 and HCT-116 cell lines was less effective, yet in the presence of copper ions, the mixture demonstrated excellent antitumor activity (IC50 at 2.75±0.30 µM for the HepG2 cell line, and 1.90±0.20 µM for the HCT-116 cell line, respectively) and the new active species was confirmed to be a PPAH copper complex with a 1:1 ratio by spectral analysis. The excellent antitumor activity of the copper complex prompted us to investigate the underlying mechanism. RT-PCR was performed to detect the changes in the expression of apoptotic genes induced by PPAH and its copper complex. However, no changes were observed when the cells were treated by the agents for 24 or 48 h, indicating that ROS were unlikely involved. Cell cycle analysis showed that both PPAH and its copper complex led to S phase arrest of the cells. The sDNA relaxation assay revealed that the PPAH-copper complex displayed dual topoisomerase inhibition for type I and II. The data suggest that the inhibition of proliferation exhibited by the PPAH copper complex may stem from its dual topoisomerase inhibition, which is rarely observed for a metal complex.

  20. STRUCTURE AND REDOX TRANSFORMATIONS OF IRON(III COMPLEXES WITH SOME BIOLOGICALLY IMPORTANT INDOLE-3-ALKANOIC ACIDS IN AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    Krisztina Kovács

    2007-06-01

    Full Text Available Interactions of a series of indole-3-alkanoic acids (with n-alkanoic acid side-chains from C1 to C4 with iron(III in acidic aqueous solutions have been shown to comprise two parallel processes including complexation and redox transformations giving iron(II hexaaquo complexes. The structure and composition of the reaction products are discussed, as analysed using a combination of instrumental techniques including 57Fe Mössbauer, vibrational and HNMR spectroscopies.

  1. Effect of glutamic acid on copper sorption onto kaolinite. Batch experiments and surface complexation modeling

    Energy Technology Data Exchange (ETDEWEB)

    Karimzadeh, Lotfallah; Barthen, Robert; Gruendig, Marion; Franke, Karsten; Lippmann-Pipke, Johanna [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Reactive Transport; Stockmann, Madlen [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes

    2017-06-01

    In this work, we study the mobility behavior of Cu(II) under conditions related to an alternative, neutrophile biohydrometallurgical Cu(II) leaching approach. Sorption of copper onto kaolinite influenced by glutamic acid (Glu) was investigated in the presence of 0.01 M NaClO{sub 4} by means of binary and ternary batch adsorption measurements over a pH range of 4 to 9 and surface complexation modeling.

  2. Antibacterial activity of chitosan and the interpolyelectrolyte complexes of poly(acrylic acid-chitosan

    Directory of Open Access Journals (Sweden)

    Hortensia Ortega-Ortiz

    2010-06-01

    Full Text Available The antimicrobial activity of chitosan and water soluble interpolyelectrolyte complexes of poly(acrylic acid-chitosan was studied. Chitosans of two different molecular weights were tested at different concentration for 0.5 to 5 g·L-1 as antimicrobial agents against P. aeruginosa and P. oleovorans. In both cases, the best microbial inhibition was obtained with the concentration of 5 g·L-1. However, the interpolyelectrolyte complexes of poly(acrylic acid-chitosan with composition φ =2 produced higher antibacterial activity than the two chitosans at the concentration of 0.5 g·L-1. The NPEC2 complex was more effective than chitosans. This could be attributed to the number of moles of the amino groups of chitosan and the carboxylic acid groups of the interpolyelectrolyte complexes poly(acrylic acid.A atividade antimicrobiana de quitosana e complexos interpolieletrolíticos hidrossoluvéis de poli(ácido acrílico-quitosana foi estudada. Quitosanas de dois diferentes pesos moleculares foram testados em diferentes concentrações, 0,5 a 5 g • L-1, como agentes antimicrobianos nas P. aeruginosa e P. oleovorans. Em ambos os casos, obteu-se a melhor inibição microbiana com a concentração de 5 g • L-1, no entanto os complexos interpolieletrolíticos de poli (ácido acrílico-quitosana com composição φ = 2 apresentaram maior atividade antibacteriana do que os dois quitosans na concentração de 0,5 g • L-1. O complexo NPEC2 foi mais eficaz do que as quitosanas, sendo que o resultado pode ser atribuído ao número de moles dos grupos aminos da quitosana e aos grupos carboxílicos dos complexos de poli(ácido acrílico.

  3. Metal-amino acid (or peptide)-nucleoside (or related bases) ternary complexes

    Energy Technology Data Exchange (ETDEWEB)

    Terron, A.; Fiol, J.J.; Herrero, L.A.; Garcia-Raso, A. [Departament de Quimica. Universitat de les Illes Balears. Palma de Mallorca. (Spain); Apella, M.C. [Cerela Centro de Referencia de Lactobacilos, Tucaman, Argentina (Antigua and Barbuda); Caubet, A.; Moreno, V. [Departament de Quimica Inorganica. Universitat de Barcelona. Barcelona (Spain)

    1997-05-01

    The knowledge of simultaneous metal ion interaction with proteins and nucleic acids is one of the most exciting subjects inside the Inorganic Biochemistry. In the last years, several groups have published articles on the synthesis and characterization of ternary complexes bringing relevant data on the structure and stability of metallo biomolecules. In this short review, the last contributions found in the literature are collected. Comments on the factors influencing the behaviour and stability of these systems are offered. (Author) 100 refs.

  4. Design and evaluation of Lumefantrine – Oleic Acid Self Nanoemulsifying Ionic Complex for Enhanced Dissolution

    Directory of Open Access Journals (Sweden)

    Pradeep Vavia

    2013-03-01

    Full Text Available Background:Lumefantrine, an antimalarial molecule has very low and variable bioavailability owing to its extremely poor solubility in water. It is recommended to be taken with milk to enhance its solubility and bioavailability. The aim of present study was to develop a Self Nanoemulsifying Delivery system (SNEDs of lumefantrine (LF to achieve rapid and complete dissolution independent of food-fat and surfactant in dissolution media.Methods:Solubility of LF in oil, co-solvent/co-surfactant and surfactant solution and emulsification efficiency of surfactant were analyzed to optimize the LF loaded self nanoemulsifying preconcentrate. Effect of LF-oleic acid complexation on emulsification, droplet size, zeta potential and dissolution were investigated. Effect of milk concentration and fat content on saturation solubility and dissolution of LF was investigated. Dissolution of marketed formulation and LF-SNEDs was carried out in pH 1.2 and pH 6.8 phosphate buffer.Results:LF exhibited very high solubility in oleic acid owing to complexation between tertiary amine of LF and carboxyl group of oleic acid (OA. Cremophore EL and medium chain monoglyceride were selected surfactant and co-surfactant, respectively. Significantly smaller droplet size (37 nm, shift in zeta potential from negative to positive value, very high drug loading in lipid based system (> 10%, no precipitation after dissolution are the major distinguish characteristics contributed by LF-OA complex in the SNED system. Saturation solubility and dissolution study in milk containing media pointed the significant increment in solubility of LF in the presence of milk-food fat. LF-SNEDs showed > 90% LF release within 30 min in pH 1.2 while marketed tablet showed almost 0% drug release.Conclusion:Self nanoemulsification promoting ionic complexation between basic drug and oleic acid hold great promise in enhancing solubility of hydrophobic drugs.

  5. Tandem Catalytic Depolymerization of Lignin by Water-Tolerant Lewis Acids and Rhodium Complexes.

    Science.gov (United States)

    Jastrzebski, Robin; Constant, Sandra; Lancefield, Christopher S; Westwood, Nicholas J; Weckhuysen, Bert M; Bruijnincx, Pieter C A

    2016-08-23

    Lignin is an attractive renewable feedstock for aromatic bulk and fine chemicals production, provided that suitable depolymerization procedures are developed. Here, we describe a tandem catalysis strategy for ether linkage cleavage within lignin, involving ether hydrolysis by water-tolerant Lewis acids followed by aldehyde decarbonylation by a Rh complex. In situ decarbonylation of the reactive aldehydes limits loss of monomers by recondensation, a major issue in acid-catalyzed lignin depolymerization. Rate of hydrolysis and decarbonylation were matched using lignin model compounds, allowing the method to be successfully applied to softwood, hardwood, and herbaceous dioxasolv lignins, as well as poplar sawdust, to give the anticipated decarbonylation products and, rather surprisingly, 4-(1-propenyl)phenols. Promisingly, product selectivity can be tuned by variation of the Lewis-acid strength and lignin source. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  6. Analytical characterization of a ferulic acid/gamma-cyclodextrin inclusion complex.

    Science.gov (United States)

    Anselmi, Cecilia; Centini, Marisanna; Ricci, Maurizio; Buonocore, Anna; Granata, Paola; Tsuno, Takuo; Facino, Roberto Maffei

    2006-03-03

    Ferulic acid (FA) is a well-known antioxidant of natural source with promising properties as photoprotective agent (approved in Japan as sunscreen) and its derivatives (alkyl ferulates) are under screening for the prevention of photoinduced skin tumours. In the present work we describe the preparation of a solid inclusion complex between ferulic acid and gamma-cyclodextrin (gamma-CD) and its characterization by different analytical techniques: differential scanning calorimetry (DSC), X-ray diffractometry (XRD), nuclear magnetic resonance spectroscopy (1H NMR) and by supporting information of molecular modelling. All these approaches indicate that ferulic acid is able to form an association complex with gamma-CD but only 1H NMR and molecular modelling studies give an unequivocal evidence that the antioxidant molecule is embedded into the gamma-CD cavity to form an inclusion complex. In detail it is entrapped inside the hydrophobic core of gamma-CD with the lipophilic aromatic ring and the ethylenic moieties, leaving the more polar functional groups close to wider rim or outside the cavity.

  7. Colloidal particles derived from a complex of phosphotungstic Acid and ethoxylated surfactants.

    Science.gov (United States)

    Sweeney, Maura A; Smith, Thomas W; Croucher, Melvin; Langner, Andreas; Miri, Massoud; Klymachyov, Alex; Kaplan, Sam; Tshudy, Dwight

    2002-09-01

    Stable, colloidal sols of submicron size were prepared by titration of aqueous solutions of alkylene oxide surfactants with phosphotungstic acid, H(3)PW(12)O(40) (PTA), followed by neutralization with ammonium or potassium hydroxide. The stoichiometry of the complex between phosphotungstic acid and the ethoxylated surfactant was determined by (1)H and (31)P NMR and was dependent upon the degree of ethoxylation. For example, in the ethoxylated octylphenol having 9-10 ethylene oxide units, Triton X-100, the mole ratio of surfactant to PTA was 4.5. In the ethoxylated octylphenol having 70 ethylene oxide units, Triton X-705, the mole ratio of surfactant to PTA was 1. Prior to nucleation of particles, phosphotungstic acid forms an apparent yellow charge transfer complex with ethoxylated alkylphenol surfactants, typified by Triton X-405. This complex is characterized by an absorption spectrum that is the sum of the spectra of Triton X-405 and PTA with a very weak shoulder at 400-500 nm. Particles were nearly monodisperse and their size was dependent on the nonionic surfactant employed, the heteropolyacid, and the rate of addition of heteropolyacid solution.

  8. Silver(I-complexes with an itaconic acid-based hydrogel

    Directory of Open Access Journals (Sweden)

    Mićić Maja M.

    2009-01-01

    Full Text Available Silver(I itaconic acid-based hydrogel complexes were synthesized and characterized in order to examine the potential use of these systems; FTIR, AFM, in vitro fluid-uptake, metal sorption and antibacterial activity assay measurements were used for the characterization. Metal (silver(I ion uptaken by IA-based hydrogels was determined by inductively coupled plasma mass spectrometry. The coordination sites for metal ions were identified and the stability in in vitro condition was determined. Incorporation of silver(I ions into hydrogels and the influence of these ions on the diffusion properties of hydrogels were analyzed and discussed, too; it was found that the itaconic acid moiety in hydrogels is the determining factor which influences metal ion binding and therefore fluid uptake inside the polymeric network. Furthermore, silver(I itaconic acid-based hydrogel showed a satisfactory antibacterial activity. The most advanced feature of these materials is that the silver ions embedded throughout the networks leaches out via controlled manner with time in aqueous media. Therefore, the ions escape from the swollen networks with time and interact with the bacteria. Because of a good dispersion of silver ions in Ag(I-P(HEMA/2IA hydrogel complex, we have evaluated the antibacterial activity for this sample. As expected, the number of colonies grown surrounding the Ag(I- -P(HEMA/2IA hydrogel complex was found to be almost nil, whereas the pure P(HEMA/2IA hydrogel did not show any effect on Escherichia coli. Therefore, we conclude that the Ag(I-P(HEMA/IA hydrogel complexes are excellent antibacterial materials. Due to these facts, the silver ion IA- -based hydrogel complexes reported here might be used as smart materials in the range of biomedical applications, including drug-delivery devices, biosensors, wound healing dressings, tissue reconstruction and organ repair.

  9. Identification of different coordination geometries by XAFS in copper(II) complexes with trimesic acid

    Science.gov (United States)

    Gaur, A.; Klysubun, W.; Soni, Balram; Shrivastava, B. D.; Prasad, J.; Srivastava, K.

    2016-10-01

    X-ray absorption spectroscopy (XAS) is very useful in revealing the information about geometric and electronic structure of a transition-metal absorber and thus commonly used for determination of metal-ligand coordination. But XAFS analysis becomes difficult if differently coordinated metal centers are present in a system. In the present investigation, existence of distinct coordination geometries around metal centres have been studied by XAFS in a series of trimesic acid Cu(II) complexes. The complexes studied are: Cu3(tma)2(im)6 8H2O (1), Cu3(tma)2(mim)6 17H2O (2), Cu3(tma)2(tmen)3 8.5H2O (3), Cu3(tma) (pmd)3 6H2O (ClO4)3 (4) and Cu3(tma)2 3H2O (5). These complexes have not only Cu metal centres with different coordination but in complexes 1-3, there are multiple coordination geometries present around Cu centres. Using XANES spectra, different coordination geometries present in these complexes have been identified. The variation observed in the pre-edge features and edge features have been correlated with the distortion of the specific coordination environment around Cu centres in the complexes. XANES spectra have been calculated for the distinct metal centres present in the complexes by employing ab-initio calculations. These individual spectra have been used to resolve the spectral contribution of the Cu centres to the particular XANES features exhibited by the experimental spectra of the multinuclear complexes. Also, the variation in the 4p density of states have been calculated for the different Cu centres and then correlated with the features originated from corresponding coordination of Cu. Thus, these spectral features have been successfully utilized to detect the presence of the discrete metal centres in a system. The inferences about the coordination geometry have been supported by EXAFS analysis which has been used to determine the structural parameters for these complexes.

  10. Zinc complexes of the antibacterial drug oxolinic acid: structure and DNA-binding properties.

    Science.gov (United States)

    Tarushi, Alketa; Psomas, George; Raptopoulou, Catherine P; Kessissoglou, Dimitris P

    2009-06-01

    The neutral mononuclear zinc complexes with the quinolone antibacterial drug oxolinic acid in the absence or presence of a nitrogen donor heterocyclic ligand 2,2'-bipyridine or 1,10-phenanthroline have been synthesized and characterized. The experimental data suggest that oxolinic acid is on deprotonated mode acting as a bidentate ligand coordinated to the metal ion through the ketone and one carboxylato oxygen atoms. The crystal structures of (chloro)(oxolinato)(2,2'-bipyridine)zinc(II), 2, and bis(oxolinato)(1,10-phenanthroline)zinc(II), 3, have been determined with X-ray crystallography. The biological activity of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT DNA) with UV and fluorescence spectroscopies. UV studies of the interaction of the complexes with DNA have shown that they can bind to CT DNA and the DNA-binding constants have been calculated. Competitive studies with ethidium bromide (EB) have shown that complex 3 exhibits the ability to displace the DNA-bound EB indicating that it binds to DNA in strong competition with EB.

  11. Competition between humic acid and carbonates for rare earth elements complexation.

    Science.gov (United States)

    Pourret, Olivier; Davranche, Mélanie; Gruau, Gérard; Dia, Aline

    2007-01-01

    The competitive binding of rare earth elements (REE) to humic acid (HA) and carbonates was studied experimentally at various pH and alkalinity values by combining ultrafiltration and inductively coupled plasma mass spectrometry techniques. The results show that the REE species occur as binary humate or carbonate complexes but not as ternary REE-carbonate-humate as previously proposed. The results also reveal the strong pH and alkalinity dependence of the competition as well as the existence of a systematic fractionation across the REE series. Specifically, carbonate complexation is at a maximum at pH 10 and increase with increasing alkalinity and with the atomic number of the REE (LuCO(3)>LaCO(3)). Modeling of the data using Model VI and recently published stability constants for complexation of REE by humic acid well reproduced the experimental data, confirming the ability of Model VI to accurately determine REE speciation in natural waters. This modeling also confirms the reliability of recently published stability constants. This work shed more light not only on the competition between carbonates and HA for REE complexation but also on the reliability of WHAM 6 and Model VI for calculating the speciation of REE with organic matter in alkaline organic-rich water.

  12. Photoinduced electron transfer reactions of ruthenium(II)-complexes containing amino acid with quinones.

    Science.gov (United States)

    Eswaran, Rajkumar; Kalayar, Swarnalatha; Paulpandian, Muthu Mareeswaran; Seenivasan, Rajagopal

    2014-05-01

    With the aim of mimicking, at basic level the photoinduced electron transfer process in the reaction center of photosystem II, ruthenium(II)-polypyridyl complexes, carrying amino acids were synthesized and studied their photoinduced electron transfer reactions with quinones by steady state and time resolved measurements. The reaction of quinones with excited state of ruthenium(II)-complexes, I-V in acetonitrile has been studied by luminescence quenching technique and the rate constant, k(q), values are close to the diffusion controlled rate. The detection of the semiquinone anion radical in this system using time-resolved transient absorption spectroscopy confirms the electron transfer nature of the reaction. The semiclassical theory of electron transfer has been successfully applied to the photoluminescence quenching of Ru(II)-complexes with quinones.

  13. Electron transfer reactions of osmium(II) complexes with phenols and phenolic acids

    Science.gov (United States)

    Rajeswari, Angusamy; Ramdass, Arumugam; Muthu Mareeswaran, Paulpandian; Velayudham, Murugesan; Rajagopal, Seenivasan

    2016-07-01

    Three [Os(NN)3]2+ complexes (NN = polypyridine) with ligands of varying hydrophobicity were synthesized and characterized by NMR spectral techniques. The geometry of the molecules are optimized by DFT calculations. The interaction between [Os(NN)3]2+ complexes and phenolate ion in ground state is confirmed by absorption spectral study and the binding constant values are in the range of 3-740 M-1. The photoinduced electron transfer reaction of these [Os(NN)3]2+ complexes with phenols and phenolic acids at pH 12.5 leads to the formation of phenoxyl radical confirmed through transient absorption spectral study. Binding constants and electron transfer rate constants within the [Os(NN)3]2+-phenolate ion adduct account for the change for the overall quenching constant with the change of structure of reactants.

  14. Synthesis and Crystal Structure of a Complex of Melamine with Benzoic Acid

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiu-lian

    2008-01-01

    A new complex of melamine(MA) with benzoic acid(HBA) was prepared,affording [(HMA+)(BA-)]·2H2O.Each HBA molecule is deprotonated and one triazine nitrogen atom of MA is protonated,The adjacent HMA+ cations are hydrogen bonded to alternate sides of the (HMA+)∞ ribbons to generate indention 1D tapes,which are extended into the hydrogen bond present in the complex are anion/water and amino/water tape structures,The hydrogen-bonding patterns consist of alternate 6,10-membered rings sharing two edges,Infrared(IR) spectroscopy conforms that proton transfer has taken place in the complex.

  15. Hydration of AN Acid Anhydride: the Water Complex of Acetic Sulfuric Anhydride

    Science.gov (United States)

    Smith, CJ; Huff, Anna; Mackenzie, Becca; Leopold, Ken

    2017-06-01

    The water complex of acetic sulfuric anhydride (ASA, CH_{3}COOSO_{2}OH) has been observed by pulsed nozzle Fourier transform microwave spectroscopy. ASA is formed in situ in the supersonic jet via the reaction of SO_{3} and acetic acid and subsequently forms a complex with water during the expansion. Spectra of the parent and fully deuterated form, as well as those of the species derived from CH_{3}^{13}COOH, have been observed. The fitted internal rotation barrier of the methyl group is 219.599(21), \\wn indicating the complexation with water lowers the internal rotation barrier of the methyl group by 9% relative to that of free ASA. The observed species is one of several isomers identified theoretically in which the water inserts into the intramolecular hydrogen bond of the ASA. Aspects of the intermolecular potential energy surface are discussed.

  16. Antibacterial activity of Pd(II) complexes with salicylaldehyde-amino acids Schiff bases ligands.

    Science.gov (United States)

    Rîmbu, Cristina; Danac, Ramona; Pui, Aurel

    2014-01-01

    Palladium(II) complexes with Schiff bases ligands derived from salicylaldehyde and amino acids (Ala, Gly, Met, Ser, Val) have been synthesized and characterized by Fourier transform (FT)-IR, UV-Vis and (1)H-NMR spectroscopy. The electrospray mass spectrometry (ES-MS) spectrometry confirms the formation of palladium(II) complexes in 1/2 (M/L) molar ratio. All the Pd(II) complexes 1, [Pd(SalAla)2]Cl2; 2, [Pd(SalGly)2]Cl2; 3, [Pd(SalMet)2]Cl2; 4, [Pd(SalSer)2]Cl2; 5, [Pd(SalVal)2]Cl2; have shown antibacterial activity against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli.

  17. Electrochemiluminescence Study of Europium (III Complex with Coumarin3-Carboxylic Acid

    Directory of Open Access Journals (Sweden)

    Stefan Lis

    2008-01-01

    Full Text Available The europium (III complex of coumarin-3-carboxylic acid (C3CA has been prepared and characterized on the basis of elemental analysis, IR, and emission (photoluminescence and electrochemiluminescence spectroscopy. The synthesised complex having a formula Eu(C3CA2(NO3(H2O2 was photophysically characterized in solution and in the solid state. Electrochemiluminescence, ECL, of the system containing the Eu(III/C3CA complex was studied using an oxide-covered aluminium electrode. The goal of these studies was to show the possibility of the use of electrochemical excitation of the Eu(III ion in aqueous solution for emission generation. The generated ECL emission was very weak, and therefore its measurements and spectral analysis were carried out with the use of cut-off filters method. The studies proved a predominate role of the ligand-to-metal energy transfer (LMET in the generated ECL.

  18. Influence of Humic Acid Complexation with Metal Ions on Extracellular Electron Transfer Activity.

    Science.gov (United States)

    Zhou, Shungui; Chen, Shanshan; Yuan, Yong; Lu, Qin

    2015-11-23

    Humic acids (HAs) can act as electron shuttles and mediate biogeochemical cycles, thereby influencing the transformation of nutrients and environmental pollutants. HAs commonly complex with metals in the environment, but few studies have focused on how these metals affect the roles of HAs in extracellular electron transfer (EET). In this study, HA-metal (HA-M) complexes (HA-Fe, HA-Cu, and HA-Al) were prepared and characterized. The electron shuttle capacities of HA-M complexes were experimentally evaluated through microbial Fe(III) reduction, biocurrent generation, and microbial azoreduction. The results show that the electron shuttle capacities of HAs were enhanced after complexation with Fe but were weakened when using Cu or Al. Density functional theory calculations were performed to explore the structural geometry of the HA-M complexes and revealed the best binding sites of the HAs to metals and the varied charge transfer rate constants (k). The EET activity of the HA-M complexes were in the order HA-Fe > HA-Cu > HA-Al. These findings have important implications for biogeochemical redox processes given the ubiquitous nature of both HAs and various metals in the environment.

  19. DNA binding mode of novel tetradentate amino acid based 2-hydroxybenzylidene-4-aminoantipyrine complexes

    Science.gov (United States)

    Raman, N.; Sobha, S.; Selvaganapathy, M.; Mahalakshmi, R.

    2012-10-01

    Few transition metal complexes of tetradentate N2O2 donor Schiff base ligands containing 2-hydroxybenzylidene-4-aminoantipyrine and amino acids (alanine/valine) abbreviated to KHL1/KHL2 have been synthesized. All the metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic data. The Schiff bases KHL1/KHL2 are found to act as tetradentate ligands using N2O2 donor set of atoms leading to a square-planar geometry for the complexes around the metal ions. The binding behaviors of the complexes to calf thymus DNA have been investigated by absorption spectra, viscosity measurements and cyclic voltammetry. The DNA binding constants reveal that all these complexes interact with DNA through minor groove binding mode. The studies on mechanism of photocleavage reveal that singlet oxygen (1O2) and superoxide anion radical (O2rad -) may play an important role in the photocleavage. The Schiff bases and their metal complexes have been screened for their in vitro antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, Klebsiella pneumoniae and antifungal activities against Aspergillus niger, Fusarium solani, Culvularia lunata, Rhizoctonia bataicola and Candida albicans by MIC method.

  20. Mn(II) complexes with bipyridine, phenanthroline and benzoic acid: Biological and catalase-like activity

    Indian Academy of Sciences (India)

    Ibrahim Kani; Özlem Atlier; Kiymet Güven

    2016-04-01

    Five mononuclear Mn(II) complexes, [Mn(phen)2(ClO4)2] (1), [Mn(phen)3](ClO4)2(H2CO3)2(2), [Mn(bipy)2(ClO4)2] (3), [Mn(bipy)3](ClO4)2) (4), and Mn(phen)2(ba)(H2O)](ClO4)(CH3OH) (5), where bipy = 2,2’-bipyridine, phen = 1,10-phenanthroline, and ba = benzoic acid were prepared and characterized by Xray, IR and UV-Vis spectroscopies, and their catalase-like and biological activities were studied. The presence of two different types and the number of chelating NN-donor neutral ligands allowed for analysis of their effects on the catalase and biological activities. It was observed that the presence and number of phen ligands improved the activity more than the bipy ligand. Complexes 1 and 2, which contain more basic phen ligands, disproportionate H2O2 faster than complexes 3 and 4, which contain less basic bipy ligands. The in vitro antimicrobial activities of all the complexes were also tested against seven bacterial strains by microdilution tests. All the bacterial isolates demonstrated sensitivity to the complexes and the antifungal (anticandidal) activities of the Mn(II) complexes were remarkably higher than the reference drug ketoconazole.

  1. Binary and ternary complexes of some inner transition metal ions with amino acids and acetyl acetone

    Science.gov (United States)

    Abu-Eittah, R. H.; Abdou, M. M.; Salem, M. B.

    1998-05-01

    The stability constants of the 1:1 and 1:2 (whenever possible) complexes formed between La3+, Ce3+, Th4+ and the amino acid anions L-alaninate, L-phenylalaninate and L-histidinate were determined by potentiometric titration in aqueous solution (25± 1 ^circC, I = 0.1 M KCl) and compared together with the constants previously determined. The various formation degree of the resulting M(L) and M(L)2 were determined. In order to relate the formation degree of M(L) and M(L)2 with the basicity of the amino acid anion (L^-), the acidity constants of the protonated amino acids, H2L^+, were also measured. The main results of this work prove that Th4+ ion forms the strongest complex with the studied amino acids. It is the only ion which forms a 1:2 complex. The heterocyclic ring of histidine plays a significant role in complexing with the studied metal ions as is clearly seen from the distribution of the degree of formation of the different complexes. The stability constants of the 1:1:1, 1:2:1 and 1:1:2 complexes formed between La3+, Ce3+, Th4+ and the anions L-alaninate, L-phenylalaninate and L-histidinate together with the acetyl acetonate ion were also determined following the same experimental set up used in the study of the simple complexes. The mixed-ligand complexes turned out to be very much stronger than the simple ligand complexes. Formation of a mixed ligand complex can be considered as a type of senergism. Les constantes de stabilité des complexes 1:1 et 2:2 (lorsque cela est possible) formés entre La3+, Ce3+, Th4+ et les anions aminoacides L-alaninate, L-phénylalaninate et L-histidinate ont été déterminées par dosage potentiométrique en solution aqueuse (25± 1 ^circC, I = 0,1 M KCl), et comparées à celles de la littérature. Les différents degrés de formation de M(L) et M(L)2 ont été quantifiés. Pour mettre en évidence la relation entre le degré de formation de M(L) et M(L)2 et la basicité des anions aminoacides (L^-), les constantes d

  2. STUDY ON POLYMER-RARE EARTH METAL ION COMPLEXES I. FLUORESCENT PROPERTIES OF POLY(ACRYLIC ACID-CO-4-VINYLPYRIDINE)-RARE EARTH METAL COMPLEXES

    Institute of Scientific and Technical Information of China (English)

    LU Hong; FANG Shibi; JIANG Yingyan

    1987-01-01

    A kind of copolymer of acrylic acid and vinylpyridine was synthesized and the fluorescent properties of the complexes of the copolymer with Eu3+ or Tb3+ were studied. It was found that the fluorescence intensity of the complexes of the copolymer with Eu3+ was 20 times as high as that of the complexes of polyacrylic acid with Eu3+ and twice as high as that of the complexes of polyvinylpyridine with Eu3+. The effects of the composition of the copolymer and the content of Eu3+ or Tb3+ in the complexes were studied.The fluorescence lifetime of the complexes was measured and it was found that two or more kinds of energy transfer mechanism existed.

  3. Effect of ionic strength on complexation of Pu(IV) with humic acid

    Energy Technology Data Exchange (ETDEWEB)

    Szabo, G.; Guezi, J. [National Research Inst. for Radiobiology and Radiohygiene, Budapest (Hungary); Reiller, P. [Commissariat a l' Energie Atomique, CE Saclay, Nuclear Energy Div./DPC/SECR, Lab. de Speciation des Radionucleides et des Molecules, Gif-sur-Yvette (France); Miyajima, T. [Dept. of Chemistry, Saga Univ. (Japan); Bulman, R.A. [Radiation Protection Div., Health Protection Agency, Chilton, Didcot (United Kingdom)

    2010-07-01

    Successful geochemical modelling of the migration of radioactive materials, such as the transuranic elements, from nuclear waste repositories is dependent upon an understanding of their interaction with biogeopolymers such as humic acids, the most likely complexing agents in groundwaters. An established silica/humic acid composite has been evaluated as a model substrate for naturally occurring humate-coated minerals that are likely to be present in the vicinity of the repositories. The binding of Pu(IV), the highly likely oxidation station, by the silica/humic substrate was examined at pH 4 in the range 0.02 to 3.00 M NaClO{sub 4} by the titration method. Pu(IV)-humate conditional stability constants have been evaluated from data obtained from these experiments by using non-linear regression of binding isotherms. The results have been interpreted in terms of complexes of 1: 1 stoichiometry. Analysis of the complex formation dependency with ionic strength shows that the effect of ionic strength on humate complexation of Pu(IV) is not dramatically pronounced. The complexation constants are evaluated for the humate interaction with Pu{sup 4-} and Pu(OH){sub 3}{sup +}, at pH 4. The complexation constants are found, respectively, to be log{sup HA}{beta}{sup 0}(Pu{sup 4+}) = 16.6 {+-} 0.3 and log{beta}{sup 0}{sub 1.3.1} = 46.6 {+-} 2.3. The estimations through analogy from previous results a are in agreement with these new experimental data (orig.)

  4. [Forming mechanism of humic acid-kaolin complexes and the adsorption of trichloroethylene].

    Science.gov (United States)

    Zhu, Xiao-jing; He, Jiang-tao; Su, Si-hui

    2015-01-01

    The interaction between soil organic components and mineral components was explored in this study. Humic acid and kaolin were used for the preparation of organic-mineral complexes with different contents of organic matter, for experimental study of the adsorption of trichloroethylene. The results showed that the adsorption of trichlorethylene fitted the Freundlich isotherm model. The existence of interaction between humic acid and kaolin was indicated by the significant difference between the actual value and the theoretically overlaid value of the adsorption capacity. With various characterizations, such as FTIR and surface area & pore analysis, the mechanism of interaction between humic acid and kaolin was suggested as follows. When their contents were low, humic acid molecules firstly loaded on the surface binding sites of kaolin. Then with the content increased, as O/M( organic-mineral mass ratio) was 0.02-0.04, some surface pores of kaolin were filled by part of the molecules. After reaching a relatively stable stage, as O/M was 0.04-0.08, humic molecules continued to load on the surface of kaolin and formed the first humic molecule-layer. With humic acid content continued increasing, as O/M was 0.08-0.10, more humic molecules attached to kaolin surface through the interaction with the first layer of molecules and then formed the second layer. O/M was 0.10-0.16 as the whole second layer stage, meanwhile the first layer was compressed. Then when O/M was 0.16-0.4, there were still some humic loadings onto the second layer as the third layer, and further compressed the inner humic acid layers. Besides, some humic acid molecules or aggregates might go on attaching to form as further outer layer.

  5. Matrix isolation infrared spectra of O-H· · · π Hydrogen bonded complexes of Acetic acid and Trifluoroacetic acid with Benzene

    Indian Academy of Sciences (India)

    PUJARINI BANERJEE; INDRANI BHATTACHARYA; TAPAS CHAKRABORTY

    2016-10-01

    Mid infrared spectra of two O–H· · · π hydrogen-bonded binary complexes of acetic acid (AA) and trifluoroacetic acid (F₃AA) with benzene (Bz) have been measured by isolating the complexes in an argon matrix at ∼8 K. In a matrix isolation condition, the O–H stretching fundamentals (νO−H) of the carboxylic acid groups of the two molecules are observed to have almost the same value. However, the spectral red-shifts of νO−H bands of the two acids on complexation with Bz are largely different, 90 and 150 cm⁻¹ for AA and F₃AA, respectively. Thus, the O–H bond weakening of the two acids upon binding with Bz in a non-interacting environment follows the sequence of their ionic dissociation tendencies (pKa) in aqueous media. Furthermore, ΔνO−H of the latter complex is the largest among the known π-hydrogen bonded binary complexes of prototypical O–H donors reported so far with respect to Bz as acceptor. It is also observed that the spectral shifts (ΔνO−H) of phenol-Bz and carboxylic acid-Bz complexes show similar dependence on the acidity factor (pKa). Electronic structure theory has been used to suggest suitable geometries of the complexes that are consistent with the measured IR spectral changes. Calculation at MP2/6-311++G (d, p) level predicts a T-shaped geometry for both AA-Bz and F₃AA-Bz complexes, and the corresponding binding energies are 3.0 and 4.5 kcal/mol, respectively. Natural Bond Orbital (NBO) analysis has been performed to correlate the observed spectral behavior of the complexes with the electronic structure parameters.

  6. The radiolysis of CMPO: effects of acid, metal complexation and alpha vs. gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bruce J. Mincher; Stephen P. Mezyk; Gary S. Groenewold

    2016-05-01

    Abstract The group actinide/lanthanide complexing agent octylphenylcarbamoylmethyl phosphine oxide (CMPO) has been examined for its radiation stability by measuring the kinetics of its reactions with free radicals in both the aqueous and organic phases for the free and metal-complexed ligand, identifying its degradation products for both alpha and gamma irradiation, measuring the effects on solvent extraction performance, and measuring the G-values for its degradation under various conditions. This includes the G-values for CMPO in the absence of, and in contact with the acidic aqueous phase, where it is shown that the acidic aqueous phase provides radio-protection for this ligand. It was found that both solvent and metal complexation affect the kinetics of the reaction of the •NO3 radical, a product of HNO3 radiolysis, with CMPO. For example, CMPO complexed with lanthanides has a rate constant for this reaction an order of magnitude higher than for the free ligand, and the reaction for the free ligand in the organic phase is about three times faster than in the aqueous phase. In steady state radiolysis kinetics it was determined that HNO3, although not NO3- anion, provides radio-protection to CMPO, with the G-value for its degradation decreasing with increasing acidity, until it was almost completely suppressed by irradiation in contact with 5 M HNO3. The same degradation products were produced by irradiation with alpha and gamma-sources, except that the relative abundances of these products varied. For example, the product of C-C bond scission was produced only in low amounts for gamma-radiolysis, but it was an important product for samples irradiated with a He ion beam. These results are compared to the new data appearing in the literature on DGA radiolysis, since CMPO and the DGAs both contain the amide functional group.

  7. Planned Complex Occupation-related Suicide by Sulfuric Acid Ingestion and Thorax Stab Wound: Case Report

    Directory of Open Access Journals (Sweden)

    Pasquale Beltempo

    2015-12-01

    Full Text Available Sulfuric acid is a colourless, odorless liquid, which causes typical injury patterns such as cutaneous and ocular burns, respiratory complications from inhalation, and ingestion injuries (coagulative necrosis of the mucosa, gastric and intestinal perforations with significant dermal and mucosal injury because of its corrosive action. Most injuries caused by sulfuric acid ingestion are accidental, especially in the paediatric population. Intentional cases of ingestion have rarely been reported in adults as a method of suicide following a major depressive disorder. In this paper, we report the case of a 44-year-old woman who was found dead outside her home with a retained fillet knife embedded in her left chest wall and cutaneous chemical burns extending from her mouth down her chin and anterior torso. During the crime scene investigation, a half empty bottle of chemical drain cleaner containing concentrated sulfuric acid was found next to her body. An autopsy revealed chemical burns to the tongue, trachea, larynx, pharynx and oesophagus along with a blackish fluid in the peritoneal cavity. Histological analyses showed extensive corrosive changes in the gastrointestinal tract. Toxicological screening of blood and urine samples was negative; gastric contents contained a high quantity of concentrated (≈ 96% sulfuric acid with a pH value of < 1.0. Death was attributed to shock following sulfuric acid ingestion. Circumstantial evidence and autopsy findings proved that the manner of death was suicidal. Complex suicides can be challenging for the forensic pathologist because of the plurality of methods used. The authors highlight the importance of systematical exhaustive postmortem investigation in order to ascertain the cause and manner of death in cases of planned complex suicide.

  8. Bioavailability of an R-α-Lipoic Acid/γ-Cyclodextrin Complex in Healthy Volunteers.

    Science.gov (United States)

    Ikuta, Naoko; Okamoto, Hinako; Furune, Takahiro; Uekaji, Yukiko; Terao, Keiji; Uchida, Ryota; Iwamoto, Kosuke; Miyajima, Atsushi; Hirota, Takashi; Sakamoto, Norihiro

    2016-06-15

    R-α-lipoic acid (R-LA) is a cofactor of mitochondrial enzymes and a very strong antioxidant. R-LA is available as a functional food ingredient but is unstable against heat or acid. Stabilized R-LA was prepared through complexation with γ-cyclodextrin (CD), yielding R-LA/CD. R-LA/CD was orally administered to six healthy volunteers and showed higher plasma levels with an area under the plasma concentration-time curve that was 2.5 times higher than that after oral administration of non-complexed R-LA, although the time to reach the maximum plasma concentration and half-life did not differ. Furthermore, the plasma glucose level after a single oral administration of R-LA/CD or R-LA was not affected and no side effects were observed. These results indicate that R-LA/CD could be easily absorbed in the intestine. In conclusion, γ-CD complexation is a promising technology for delivering functional but unstable ingredients like R-LA.

  9. Bioavailability of an R-α-Lipoic Acid/γ-Cyclodextrin Complex in Healthy Volunteers

    Directory of Open Access Journals (Sweden)

    Naoko Ikuta

    2016-06-01

    Full Text Available R-α-lipoic acid (R-LA is a cofactor of mitochondrial enzymes and a very strong antioxidant. R-LA is available as a functional food ingredient but is unstable against heat or acid. Stabilized R-LA was prepared through complexation with γ-cyclodextrin (CD, yielding R-LA/CD. R-LA/CD was orally administered to six healthy volunteers and showed higher plasma levels with an area under the plasma concentration-time curve that was 2.5 times higher than that after oral administration of non-complexed R-LA, although the time to reach the maximum plasma concentration and half-life did not differ. Furthermore, the plasma glucose level after a single oral administration of R-LA/CD or R-LA was not affected and no side effects were observed. These results indicate that R-LA/CD could be easily absorbed in the intestine. In conclusion, γ-CD complexation is a promising technology for delivering functional but unstable ingredients like R-LA.

  10. Catalytic decomposition of hydrogen peroxide on anthraquinonecyanine and phthalocyanine metal complexes in acid and alkaline electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Pobedinskiy, S.N.; Trofimenko, A.A.; Zharnikova, M.A.

    1985-12-01

    A study of octaoxyanthraquinonecyanines (OOATsM) and phthalocyanines (FTs) of cobalt, iron, and manganese determined their catalytic activity in the hydrogen peroxide decomposition reaction. Hydrogen peroxide decomposition on OOATsM and FTs of the metals studied follows the kinetic mechanisms of a reaction of the first order regardless of the central ion of the metal. Complexes with a central atom of iron are most active in decomposition of hydrogen peroxide. Catalytic activity of FTsFe exceeds that of FTsCo more than 10-fold. FTs are 10-fold greater than OOATsM in catalytic activity. Change from an acid to an alkali medium did not affect the kinetic mechanisms of the decomposition reaction but the reaction rate on both a carrier and on metal complexes is higher in an alkaline medium than in an acid medium. The affect of an alkaline medium on the hydrogen peroxide decomposition rate is greater for FTS complexes than for anthraquinone-cyanines. 5 references, 2 figures.

  11. Molecular structure of hydrated complex of trigonelline with L(+)-tartaric acid

    Science.gov (United States)

    Dega-Szafran, Z.; Dutkiewicz, G.; Kosturkiewicz, Z.; Szafran, M.; Barczyński, P.

    2011-04-01

    Crystal structure of the 1:1:1 complex of trigonelline with L(+)-tartaric acid and water has been determined by X-ray diffraction. The crystals are monoclinic, space group P2 1. Trigonelline is protonated and it is linked with the semi-tartrate anion by the COOH⋯OOC hydrogen bond of 2.475(2) Å. The semi-tartrate anions form infinite chains through the COOH⋯OOC hydrogen bonds of 2.599(2) Å. Water molecules play a role of double donors and double acceptors of hydrogen bonds with the semi-tartrate anions and link them into a three-dimensional net. In the optimized structure of the title complex at the B3LYP/6-31G(d,p) level of theory trigonelline is linked with L(+)-tartaric acid by the COO⋯HOOC hydrogen bond of 2.473 Å. The solid-state FTIR spectrum is consistent with the X-ray results. The 1H and 13C NMR spectra elucidate the structure of the complex investigated in aqueous solutions. The value of p Ka of trigonelline has been determined by the potentiometric titration of its hydrochloride.

  12. Water oxidation catalysis with nonheme iron complexes under acidic and basic conditions: homogeneous or heterogeneous?

    Science.gov (United States)

    Hong, Dachao; Mandal, Sukanta; Yamada, Yusuke; Lee, Yong-Min; Nam, Wonwoo; Llobet, Antoni; Fukuzumi, Shunichi

    2013-08-19

    Thermal water oxidation by cerium(IV) ammonium nitrate (CAN) was catalyzed by nonheme iron complexes, such as Fe(BQEN)(OTf)2 (1) and Fe(BQCN)(OTf)2 (2) (BQEN = N,N'-dimethyl-N,N'-bis(8-quinolyl)ethane-1,2-diamine, BQCN = N,N'-dimethyl-N,N'-bis(8-quinolyl)cyclohexanediamine, OTf = CF3SO3(-)) in a nonbuffered aqueous solution; turnover numbers of 80 ± 10 and 20 ± 5 were obtained in the O2 evolution reaction by 1 and 2, respectively. The ligand dissociation of the iron complexes was observed under acidic conditions, and the dissociated ligands were oxidized by CAN to yield CO2. We also observed that 1 was converted to an iron(IV)-oxo complex during the water oxidation in competition with the ligand oxidation. In addition, oxygen exchange between the iron(IV)-oxo complex and H2(18)O was found to occur at a much faster rate than the oxygen evolution. These results indicate that the iron complexes act as the true homogeneous catalyst for water oxidation by CAN at low pHs. In contrast, light-driven water oxidation using [Ru(bpy)3](2+) (bpy = 2,2'-bipyridine) as a photosensitizer and S2O8(2-) as a sacrificial electron acceptor was catalyzed by iron hydroxide nanoparticles derived from the iron complexes under basic conditions as the result of the ligand dissociation. In a buffer solution (initial pH 9.0) formation of the iron hydroxide nanoparticles with a size of around 100 nm at the end of the reaction was monitored by dynamic light scattering (DLS) in situ and characterized by X-ray photoelectron spectra (XPS) and transmission electron microscope (TEM) measurements. We thus conclude that the water oxidation by CAN was catalyzed by short-lived homogeneous iron complexes under acidic conditions, whereas iron hydroxide nanoparticles derived from iron complexes act as a heterogeneous catalyst in the light-driven water oxidation reaction under basic conditions.

  13. Neutron scattering shows a droplet of oleic acid at the center of the BAMLET complex.

    Science.gov (United States)

    Rath, Emma M; Duff, Anthony P; Gilbert, Elliot P; Doherty, Greg; Knott, Robert B; Church, W Bret

    2017-07-01

    The anti-cancer complex, Bovine Alpha-lactalbumin Made LEthal to Tumors (BAMLET), has intriguing broad-spectrum anti-cancer activity. Although aspects of BAMLET's anti-cancer mechanism are still not known, it is understood that it involves the oleic acid or oleate component of BAMLET being preferentially released into cancer cell membranes leading to increased membrane permeability and lysis. The structure of the protein component of BAMLET has previously been elucidated by small angle X-ray scattering (SAXS) to be partially unfolded and dramatically enlarged. However, the structure of the oleic acid component of BAMLET and its disposition with respect to the protein component was not revealed as oleic acid has the same X-ray scattering length density (SLD) as water. Employing the difference in the neutron SLDs of hydrogen and deuterium, we carried out solvent contrast variation small angle neutron scattering (SANS) experiments of hydrogenated BAMLET in deuterated water buffers, to reveal the size, shape, and disposition of the oleic acid component of BAMLET. Our resulting analysis and models generated from SANS and SAXS data indicate that oleic acid forms a spherical droplet of oil incompletely encapsulated by the partially unfolded protein component. This model provides insight into the anti-cancer mechanism of this cache of lipid. The model also reveals a protein component "tail" not associated with the oleic acid component that is able to interact with the tail of other BAMLET molecules, providing a plausible explanation of how BAMLET readily forms aggregates. Proteins 2017; 85:1371-1378. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  14. Self-assembled ternary complexes stabilized with hyaluronic acid-green tea catechin conjugates for targeted gene delivery.

    Science.gov (United States)

    Liang, Kun; Bae, Ki Hyun; Lee, Fan; Xu, Keming; Chung, Joo Eun; Gao, Shu Jun; Kurisawa, Motoichi

    2016-03-28

    Nanosized polyelectrolyte complexes are attractive delivery vehicles for the transfer of therapeutic genes to diseased cells. Here we report the application of self-assembled ternary complexes constructed with plasmid DNA, branched polyethylenimine and hyaluronic acid-green tea catechin conjugates for targeted gene delivery. These conjugates not only stabilize plasmid DNA/polyethylenimine complexes via the strong DNA-binding affinity of green tea catechin, but also facilitate their transport into CD44-overexpressing cells via receptor-mediated endocytosis. The hydrodynamic size, surface charge and physical stability of the complexes are characterized. We demonstrate that the stabilized ternary complexes display enhanced resistance to nuclease attack and polyanion-induced dissociation. Moreover, the ternary complexes can efficiently transfect the difficult-to-transfect HCT-116 colon cancer cell line even in serum-supplemented media due to their enhanced stability and CD44-targeting ability. Confocal microscopic analysis demonstrates that the stabilized ternary complexes are able to promote the nuclear transport of plasmid DNA more effectively than binary complexes and hyaluronic acid-coated ternary complexes. The present study suggests that the ternary complexes stabilized with hyaluronic acid-green tea catechin conjugates can be widely utilized for CD44-targeted delivery of nucleic acid-based therapeutics.

  15. A method for the determination of ascorbic acid using the iron(II)-pyridine-dimethylglyoxime complex

    Energy Technology Data Exchange (ETDEWEB)

    Arya, S. P.; Mahajan, M. [Haryana, Kurukshetra Univ. (India). Dept. of Chemistry

    1998-05-01

    A simple and rapid spectrophotometric method for the determination of ascorbic acid is proposed. Ascorbic acid reduces iron (III) to iron (II) which forms a red colored complex with dimethylglyoxime in the presence of pyridine. The absorbance of the resulting solution is measured at 514 nm and a linear relationship between absorbance and concentration of ascorbic acid is observed up to 14 {mu}g ml{sup -1}. Studies on the interference of substances usually associated with ascorbic acid have been carried out and the applicability of the method has been tested by analysing pharmaceutical preparations of vitamin C. [Italiano] Si propone un rapido e semplice metodo spettrofotometrico per la determinazione dell`acido ascorbico. L`acido ascorbico riduce il ferro(III) a ferro(II) che forma con la dimetilgliossima, in presenza di piridina, un complesso colorato in rosso. L`assorbanza della soluzione risultante e` misurata a 514 nm e si ottiene una relazione lineare tra assorbanza e concentrazione dell`acido ascorbico fino a 14 {mu}g ml{sup -1}. Si sono condotti studi sugli interferenti usualmente associati all`acido ascorbico ed e` stata valutata l`applicabilita` del metodo all`analisi di preparati farmaceutici di vitamina C.

  16. Dehydrogenation of Formic Acid Catalyzed by a Ruthenium Complex with an N,N′-Diimine Ligand

    KAUST Repository

    Guan, Chao

    2016-12-17

    We report a ruthenium complex containing an N,N′-diimine ligand for the selective decomposition of formic acid to H and CO in water in the absence of any organic additives. A turnover frequency of 12000 h and a turnover number of 350 000 at 90 °C were achieved in the HCOOH/HCOONa aqueous solution. Efficient production of high-pressure H and CO (24.0 MPa (3480 psi)) was achieved through the decomposition of formic acid with no formation of CO. Mechanistic studies by NMR and DFT calculations indicate that there may be two competitive pathways for the key hydride transfer rate-determining step in the catalytic process.

  17. Polymeric Framboidal Nanoparticles Loaded with a Carbon Monoxide Donor via Phenylboronic Acid-Catechol Complexation.

    Science.gov (United States)

    van der Vlies, André J; Inubushi, Ryosuke; Uyama, Hiroshi; Hasegawa, Urara

    2016-06-15

    Carbon monoxide (CO) is an essential gaseous signaling molecule in the human body. Toward the controlled delivery of CO to the target tissues or cells, nanomaterial-based CO donors have attracted growing attention. Here, we present CO-releasing polymeric nanoparticles (CONPs) prepared by simple mixing of phenylboronic acid-containing framboidal nanoparticles with the catechol-bearing CO-donor Ru(CO)3Cl(L-DOPA) via phenylboronic acid-catechol complexation. The CONPs release CO in response to cysteine and suppress the production of the pro-inflammatory mediators interleukin 6 (IL-6) and nitric oxide (NO) in lipopolysaccharide (LPS)-stimulated murine macrophages. This CONP platform may show promise in therapeutic applications of CO.

  18. IMMOBILIZATION OF GLUCOSE OXIDASE AND CELLULASE BY CHITOSAN-POLYACRYLIC ACID COMPLEX

    Institute of Scientific and Technical Information of China (English)

    WANG Lingzhi; JIANG Yingyan; ZHANG Changde; HUANG Dexiu

    1990-01-01

    This study is concerned with chitosan-polyacrylic acid complex as a carrier to immobilize glucose oxidase (GOD) and cellulase. The optimum temperature of the immobilized GOD (IG) was determined to be 60 ℃ which is higher than that of the native GOD about 40 ℃ . The optimum temperature of the immobilized cellulase (IC) was determined to be about 30 ℃ higher than that of native cellulase. Both of the optimum pH of IG and IC shifted one pH unit to acid. Immobilized enzyme may be used in more wide pH range. Their storage life are much longer compared with their native states. Both of them can be reused at least 12 times.

  19. Synthesis and Characteristic Study on Complexes of Europium(Ⅲ) and Maleic Acid Doped with Non-Fluorescent Ions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Complex of europium (Ⅲ) with maleic acid, and binuclear complexes of europium(Ⅲ)with maleic acid doped with non-fluorescent ions gadolinium, lanthanum and yttrium, were synthesized. The compositions and structures of complexes were characterized with elemental analysis, single crystal X-ray diffraction, IR and DSC-TG. Fluorescent properties were studied with fluorescence spectrum. The results indicated that the strongest fluorescent complexes were obtained when the ratio of europium and non-fluorescent ion was 8: 2. The order of Eu3+ fluorescence strengthened by three doped rare earths was Gd3+>La3+>Y3+.

  20. The acid-labile subunit of the ternary insulin-like growth factor complex in cirrhosis

    DEFF Research Database (Denmark)

    Møller, S; Juul, A; Becker, U;

    2000-01-01

    In the circulation, insulin-like growth factor-I (IGF-I) is bound in a trimeric complex of 150 kDa with IGF binding protein-3 (IGFBP-3) and the acid-labile subunit (ALS). Whereas circulating IGF-I and IGFBP-3 are reported to be low in patients with chronic liver failure, the level of ALS has...... not been described in relation to hepatic dysfunction. The aim of the present study was therefore to measure circulating and hepatic venous concentrations of ALS in relation to hepatic function and the IGF axis....

  1. Effects of alkaline earth metal ion complexation on amino acid zwitterion stability: Results from infrared action spectroscopy

    NARCIS (Netherlands)

    Bush, M. F.; Oomens, J.; Saykally, R. J.; Williams, E. R.

    2008-01-01

    The structures of isolated alkaline earth metal cationized amino acids are investigated using infrared multiple photon dissociation (IRMPD) spectroscopy and theory. These results indicate that arginine, glutamine, proline, serine, and valine all adopt zwitterionic structures when complexed with diva

  2. Synthesis, structural characterization and antimicrobial activities of diorganotin(IV) complexes with azo-imino carboxylic acid ligand: Crystal structure and topological study of a doubly phenoxide-bridged dimeric dimethyltin(IV) complex appended with free carboxylic acid groups

    Science.gov (United States)

    Roy, Manojit; Roy, Subhadip; Devi, N. Manglembi; Singh, Ch. Brajakishor; Singh, Keisham Surjit

    2016-09-01

    Diorganotin(IV) complexes appended with free carboxylic acids were synthesized by reacting diorganotin(IV) dichlorides [R2SnCl2; R = Me (1), Bu (2) and Ph (3)] with an azo-imino carboxylic acid ligand i.e. 2-{4-hydroxy-3-[(2-hydroxyphenylimino)methyl]phenylazo}benzoic acid in presence of triethylamine. The complexes were characterized by elemental analysis, IR and multinuclear NMR (1H, 13C and 119Sn) spectroscopy. The structure of 1 in solid state has been determined by X-ray crystallography. Crystal structure of 1 reveals that the compound crystallizes in monoclinic space group P21/c and is a dimeric dimethyltin(IV) complex appended with free carboxylic acid groups. In the structure of 1, the Sn(IV) atoms are hexacoordinated and have a distorted octahedral coordination geometry in which two phenoxy oxygen atoms and the azomethine nitrogen atom of the ligand coordinate to each tin atom. One of the phenoxy oxygen atom bridges the two tin centers resulting in a planar Sn2O2 core. Topological analysis is used for the description of molecular packing in 1. Tin NMR spectroscopy study indicates that the complexes have five coordinate geometry around tin atom in solution state. Since the complexes have free carboxylic acids, these compounds could be further used as potential metallo-ligands for the synthesis of other complexes. The synthesized diorganotin(IV) complexes were also screened for their antimicrobial activities and compound 2 showed effective antimicrobial activities.

  3. Formation of ternary complexes between a macrotricyclic host and hetero-guest pairs: an acid-base controlled selective complexation process.

    Science.gov (United States)

    Han, Tao; Chen, Chuan-Feng

    2007-10-11

    A triptycene-based cylindrical macrotricyclic host can include diquat and electron-rich aromatics simultaneously to form stable ternary complexes, which is stabilized not only by a charge-transfer (CT) interaction between electron-rich and electron-deficient guests but also by the face to face pi-stacking interactions between the host and the guests. Moreover, a selective complexation process between a ternary complex containing benzidine and a binary complex can be effectively controlled by the use of acid and base.

  4. Synthesis and relaxivity of polycarboxylic hydrazone rare earth complexes--Relaxivity of a -oxo-pentanedioic acid benzoyl hydrazone Gd-complexes

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Synthesis of ligand, a -oxo-pentanedioic acid benzoyl hydrazone (H2LPB), and its six rare earth (La, Pr, Nd, Sm, Gd and Er) complexes are reported. The composition and the properties of the complexes were characterized by element analysis, thermal analysis, UV, IR and 1H NMR spectra. Besides, relaxivity (R1) of Gd-complex has been determined by INVREC.Au program, using inversion recovery pulse sequences, R1=8.05 mmol.L-1.s-1. The acute toxicity of Gd-complex in animal has also been tested, and the median lethal dose (LD50) is equal to (468.2±30) mg/kg.

  5. The Crystal Structure and Behavior of Fenamic Acid-Acridine Complex Under High Pressure.

    Science.gov (United States)

    Jerzykiewicz, Lucjan; Sroka, Adam; Majerz, Irena

    2016-12-01

    The crystal structure of fenamic acid-acridine complex is determined by X-ray diffraction. The strong OHN hydrogen bond linking the complex components and other interactions responsible for packing of the molecules into a crystal are investigated within the Quantum Theory of Atom in Molecule theory. The crystal structure is compared with the structure optimized at B3LYP/6-311++G** level and with the theoretical structures optimized under systematically changed pressure. Analysis of the lattice constants, hydrogen bond lengths, and angles of the inter- and intramolecular hydrogen bond under compression is performed. The structural transformation observed at 5 GPa is connected with a change in the intermolecular OHN hydrogen bond. The proton shifts to acceptor and a new interaction in the crystal appears.

  6. THE ROTATIONAL SPECTRUM OF THE UREA\\cdot\\cdot\\cdotISOCYANIC ACID COMPLEX

    Science.gov (United States)

    Mullaney, John C.; Medcraft, Chris; Walker, Nick; Legon, Anthony; Lewis-Borrell, Luke; Golding, Bernard T.

    2016-06-01

    A dimer of urea and isocyanic acid has been generated and observed in the gas phase. The complex was generated by laser vaporisation of a rod target containing urea and copper in a 1:1 ratio, then cooled in a supersonic expansion. Six isotopologues of the complex have been characterised using a chirped pulse Fourier-transform microwave spectrometer in the frequency range 6.5-18.5 GHz. The spectra have been fitted to the Hamiltonian for an asymmetric rotor using PGOPHER. Data obtained from the 13C and 15N isotopologues confirms that all nitrogen atoms are close to the a intertial axis while the carbon atoms are not. A tentative structure will be presented.

  7. Spectroscopic, Electrochemical, and In Silico Characterization of Complex Formed between 2-Ferrocenylbenzoic Acid and DNA

    Directory of Open Access Journals (Sweden)

    Ataf Ali Altaf

    2016-01-01

    Full Text Available We present the synthesis of 2-ferrocenylbenzoic acid (FcOH and its electrochemical and spectroscopic characterization. FcOH was characterized for interaction with DNA using theoretical and experimental methods. UV-visible spectroscopy and cyclic voltammeter (CV were used for the experimental account of FcOH-DNA complex. The experimental results showed that the FcOH interacts by electrostatic mode. The binding constant (Kb and Gibbs free energy (ΔG for the FcOH-DNA complex have been estimated as 5.3 × 104 M−1 and −6.44 kcal/mol, respectively. The theoretical DNA binding of FcOH was studied with AutoDock molecular docking software. The docking studies yield good approximation with experimental data and explain the sites of binding.

  8. Lewis acid-water/alcohol complexes as hydrogen atom donors in radical reactions.

    Science.gov (United States)

    Povie, Guillaume; Renaud, Philippe

    2013-01-01

    Water or low molecular weight alcohols are, due to their availability, low price and low toxicity ideal reagents for organic synthesis. Recently, it was reported that, despite the very strong BDE of the O-H bond, they can be used as hydrogen atom donors in place of expensive and/or toxic group 14 metal hydrides when boron and titanium(III) Lewis acids are present. This finding represents a considerable innovation and uncovers a new perspective on the paradigm of hydrogen atom transfers to radicals. We discuss here the influence of complex formation and other association processes on the efficacy of the hydrogen transfer step. A delicate balance between activation by complex formation and deactivation by further hydrogen bonding is operative.

  9. Chiral Sensing of Various Amino Acids Using Induced Circularly Polarized Luminescence from Europium(III) Complexes of Phenanthroline Dicarboxylic Acid Derivatives.

    Science.gov (United States)

    Uchida, Taka-Aki; Nozaki, Koichi; Iwamura, Munetaka

    2016-09-06

    Circularly polarized luminescence (CPL) was observed from [Eu(dppda)2 ](-) (dppda=4,7-diphenyl-1,10-phenanthroline-2,9-dicarboxylic acid) and [Eu(pzpda)2 ](-) (pzpda=pyrazino[2,3-f][1,10]phenanthroline-7,10-dicarboxylic acid) in aqueous solutions containing various amino acids. The selectivity of these complexes towards amino acids enabled them to be used as chiral sensors and their behavior was compared with that of [Eu(pda)2 ](-) (pda=1,10-phenanthroline-2,9-dicarboxylic acid). As these Eu(III) complexes have achiral D2d structures under ordinary conditions, there were no CPL signals in the emission assigned to f-f transitions. However, when the solutions contained particular amino acids they exhibited detectable CPL signals with glum values of about 0.1 (glum =CPL/2 TL; TL=total luminescence). On examining 13 amino acids with these three Eu(III) complexes, it was found that whether an amino acid induced a detectable CPL depended on the Eu(III) complex ligands. For example, when ornithine was used as a chiral agent, only [Eu(dppda)2 ](-) exhibited intense CPL in aqueous solutions of 10(-2)  mol dm(-3) . Steep amino acid concentration dependence suggested that CPL in [Eu(dppda)2 ](-) and [Eu(pzpda)2 ](-) was induced by the association of four or more amino acid molecules, whereas CPL in [Eu(pda)2 ](-) was induced by association of two arginine molecules.

  10. Encapsulation of gallic acid/cyclodextrin inclusion complex in electrospun polylactic acid nanofibers: Release behavior and antioxidant activity of gallic acid.

    Science.gov (United States)

    Aytac, Zeynep; Kusku, Semran Ipek; Durgun, Engin; Uyar, Tamer

    2016-06-01

    Cyclodextrin-inclusion complexes (CD-ICs) possess great prominence in food and pharmaceutical industries due to their enhanced ability for stabilization of active compounds during processing, storage and usage. Here, CD-IC of gallic acid (GA) with hydroxypropyl-beta-cyclodextrin (GA/HPβCD-IC) was prepared and then incorporated into polylactic acid (PLA) nanofibers (PLA/GA/HPβCD-IC-NF) using electrospinning technique to observe the effect of CD-ICs in the release behavior of GA into three different mediums (water, 10% ethanol and 95% ethanol). The GA incorporated PLA nanofibers (PLA/GA-NFs) were served as control. Phase solubility studies showed an enhanced solubility of GA with increasing amount of HPβCD. The detailed characterization techniques (XRD, TGA and (1)H-NMR) confirmed the formation of inclusion complex between GA and HPβCD. Computational modeling studies indicated that the GA made an efficient complex with HPβCD at 1:1 either in vacuum or aqueous system. SEM images revealed the bead-free and uniform morphology of PLA/GA/HPβCD-IC-NF. The release studies of GA from PLA/GA/HPβCD-IC-NF and PLA/GA-NF were carried out in water, 10% ethanol and 95% ethanol, and the findings revealed that PLA/GA/HPβCD-IC-NF has released much more amount of GA in water and 10% ethanol system when compared to PLA/GA-NF. In addition, GA was released slowly from PLA/GA/HPβCD-IC-NF into 95% ethanol when compared to PLA/GA-NF. It was also observed that electrospinning process had no negative effect on the antioxidant activity of GA when GA was incorporated in PLA nanofibers.

  11. Thermal Behaviour of Some New Polyoxometalate Complexes of Ciprofloxacin with Keggin-type Heteropoly Acids

    Institute of Scientific and Technical Information of China (English)

    WANG Dun-jia; FANG Zheng-dong; HAN De-yan

    2005-01-01

    Four polyoxometalate complexes, (CPFX·HCl)3H4SiW12O40, (CPFX·HCl)3H3PW12O40, (CPFX·HCl)3H3PMo12O40 and (CPFX·HCl)4H4SiMo12O40, were prepared from ciprofloxacin hydrochloride(CPFX·HCl) reacting with HnXM12O40·nH2O(X=P,Si; M=W,Mo) in an aqueous solution, and characterized by elemental analysis, IR spectrometry and TG-DTA. The IR spectrum confirms the presence of Keggin-type anions of heteropoly acids and the characteristic functional groups of ciprofloxacin. The TG/DTA curves show that their thermal decomposition is a multi-step process including simultaneous collapse of the Keggin-type structure. At first, these compounds had a mass loss of water molecules, then several other mass losses occurred due to the decomposition of ciprofloxacin hydrochloride and its fragments with the degradation of Keggin anions. The end product of decomposition is the mixture of WO3(or MoO3) and SiO2(or P2O5), identified by X-ray diffraction and IR spectroscopy. The possible thermal decomposition mechanisms of these complexes are proposed. This study exemplified that the thermal stability of the complexes containing tungsten is much better than that of the complexes containing molybdenum.

  12. Preparation and characterization of aqueous dispersions of high amylose starch and conjugated linoleic acid complex.

    Science.gov (United States)

    Seo, Tae-Rang; Kim, Hee-Young; Lim, Seung-Taik

    2016-11-15

    Crystalline starch-CLA complexes were prepared by blending an alcoholic solution of conjugated linoleic acid (CLA) in an aqueous high-amylose maize starch dispersion. Recovery yield of CLA in the precipitates obtained by centrifuging the dispersion was dependent on reaction conditions such as temperature, time and pH. The CLA recovery reached a maximum when the reaction was performed at 90°C for 6h at neutral pH, with 67.7% of the initial CLA being co-precipitated with starch. The precipitates contained amylose-CLA complex exhibiting a V6I-type crystalline structure under X-ray diffraction analysis and a type II polymorph under DSC analysis. Ultrasonic treatment for the re-dispersed starch-CLA complex in water resulted in the reduction of hydrodynamic diameter of the complex particles to 201.5nm. The dispersion exhibited a zeta potential of -27.0mV and remained stable in an ambient storage without forming precipitates for more than 4weeks. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Synthesis and characterization of tin(II) complexes of fluorinated Schiff bases derived from amino acids.

    Science.gov (United States)

    Singh, Har Lal

    2010-07-01

    New tin(II) complexes of general formula Sn(L)(2) (L=monoanion of 3-methyl-4-fluoro-acetophenone phenylalanine L(1)H, 3-methyl-4-fluoro-acetophenone alanine L(2)H, 3-methyl-4-fluoro acetophenone tryptophan L(3)H, 3-methyl-4-fluoro-acetophenone valine L(4)H, 3-methyl-4-fluoro-acetophenone isoleucine L(5)H and 3-methyl-4-fluoro-acetophenone glycine L(6)H) have been prepared. It is characterized by elemental analyses, molar conductance measurements and molecular weight determinations. Bonding of these complexes is discussed in terms of their UV-visible, infrared, and nuclear magnetic resonance ((1)H, (13)C, (19)F and (119)Sn NMR) spectral studies. The ligands act as bidentate towards metal ions, via the azomethine nitrogen and deprotonated oxygen of the respective amino acid. Elemental analyses and NMR spectral data of the ligands with their tin(II) complexes agree with their proposed square pyramidal structures. A few representative ligands and their tin complexes have been screened for their antibacterial activities and found to be quite active in this respect. Copyright 2010 Elsevier B.V. All rights reserved.

  14. Synthesis, characterization and antioxidant/cytotoxic activity of oxovanadium(IV) complexes of methyliminodiacetic acid and ethylenediaminetetracetic acid

    Science.gov (United States)

    Ibrahim, Mohamed M.; Mersal, Gaber A. M.; Ramadan, Abdel-Motaleb M.; Shaban, Shaban Y.; Mohamed, Mahmoud A.; Al-Juaid, Salih

    2017-06-01

    Two oxovanadium(IV) complexes, viz., [VO(Me-IDA)(H2O)2] (1) and NaH[VO(EDTA)]·4H2O (2) (Me-IDA = methyliminodiacetic acid and EDTA = ethylenediaminetetraacetic acid) have been synthesized and characterized by FT-IR, UV-Vis, mass spectrometry, elemental analysis, magnetic moment and thermal analysis, as well as electrochemical measurements including cyclic voltammetry. Both compounds are monomeric with distorted octahedral geometries. Compound 2 has been structurally characterized by using X-ray crystallography. It shows an octahedral V(O)N2O3 coordination geometry, which exhibits chemically significant hydrogen bonding interactions besides showing coordination polymer formation. Compounds 1 and 2 show an irreversible redox peak around +0.80 V versus Ag/AgCl corresponding to one-electron oxidation of V(IV) to V(V). The free radical scavenging activity of compounds 1 and 2 were done using 2,2-diphenyl- 1-picrylhydrazyl (DPPH). Both compounds have shown encouraging ROS scavenging activities. The cytotoxicity effects of both compounds toward two different tumor cells (HePG2 and MCF-7) have been also studied by MTT assay. The IC50 values obtained, after 48 h incubation at 37 °C for HepG2 and MCF-7 cell lines were 74.23 and 42.04 μg/mL for compound 1 and 65.56 and 48.34 μg/mL for compound 2, respectively. Conclusively, the present investigation provides preliminary results which suggest that such compounds can be promising alternative antitumor agents.

  15. Stability constant of the lanthanum complex with humic acid; Constante de estabilidad del complejo de lantano con acido humico

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez R, M.; Solache R, M. J. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico)

    2008-07-01

    The work described here is a study on the formation of trivalent lanthanum complex with humic acid. Commercial humic acid was purified and then characterized by various analytical techniques. The stability constant determined by a radiochemical method has a worth of log {beta}{sub La},{sub AHA} = 13.6. (Author)

  16. Regulation of hepatic branched-chain alpha-keto acid dehydrogenase complex in rats fed a high-fat diet

    Science.gov (United States)

    Objective: Branched-chain alpha-keto acid dehydrogenase complex (BCKDC) regulates branched-chain amino acid (BCAA) metabolism at the level of branched chain alpha-ketoacid (BCKA) catabolism. It has been demonstrated that the activity of hepatic BCKDC is markedly decreased in type 2 diabetic animal...

  17. A NOVEL COPOLYMER-BOUND CIS- DICARBONYLRHODIUM COMPLEX FOR THE CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    YUAN Guoqing; CHEN Yuying; CHEN Rongyao

    1989-01-01

    A series of porous microspheres of linear and ethylene diacrylate (M ') cross-linked copolymers of 2 - vinylpyridine (V) and methyl acrylate (M) reacted with tetracarbonyldichlorodirhodium to form a series of cis-dicarbonylrhodium chelate complex (MVRh and MVM 'Rh). They are thermally stable yet very reactive in the carbonylation of methanol to acetic acid, and of methanol - acetic acid mixture to acetic acid and acetic anhydride with a selectivity of 100% under relatively mild and anhydrous conditions.

  18. Negative ion photoelectron spectroscopy of the copper-aspartic acid anion and its hydrated complexes

    Science.gov (United States)

    Li, Xiang; Wang, Haopeng; Bowen, Kit H.; Martínez, Ana; Salpin, Jean-Yves; Schermann, Jean-Pierre

    2010-08-01

    Negative ions of copper-aspartic acid Cu(Asp)- and its hydrated complexes have been produced in the gas phase and studied by anion photoelectron spectroscopy. The vertical detachment energies (VDE) of Cu(Asp)- and Cu(Asp)-(H2O)1,2 were determined to be 1.6, 1.95, and 2.20 eV, respectively. The spectral profiles of Cu(Asp)-(H2O)1 and Cu(Asp)-(H2O)2 closely resembled that of Cu(Asp)-, indicating that hydration had not changed the structure of Cu(Asp)- significantly. The successive shifts to higher electron binding energies by the spectra of the hydrated species provided measures of their stepwise solvation energies. Density functional calculations were performed on anionic Cu(Asp)- and on its corresponding neutral. The agreement between the calculated and measured VDE values implied that the structure of the Cu(Asp)- complex originated with a zwitterionic form of aspartic acid in which a copper atom had inserted into the N-H bond.

  19. Interaction of water-soluble amino acid Schiff base complexes with bovine serum albumin: Fluorescence and circular dichroism studies

    Science.gov (United States)

    Gharagozlou, Mehrnaz; Boghaei, Davar M.

    2008-12-01

    Fluorescence spectroscopy in combination with circular dichroism (CD) spectroscopy were used to investigate the interaction of water-soluble amino acid Schiff base complexes, [Zn(L 1,2)(phen)] where phen is 1,10-phenanthroline and H 2L 1,2 is amino acid Schiff base ligands, with bovine serum albumin (BSA) under the physiological conditions in phosphate buffer solution adjusted to pH 7.0. The quenching mechanism of fluorescence was suggested as static quenching according to the Stern-Volmer equation. Quenching constants were determined using the Stern-Volmer equation to provide a measure of the binding affinity between amino acid Schiff base complexes and BSA. The thermodynamic parameters Δ G, Δ H and Δ S at different temperatures (298, 310 and 318 K) were calculated. The results indicate that the hydrophobic and hydrogen bonding interactions play a major role in [Zn(L 1)(phen)]-BSA association, whereas hydrophobic and electrostatic interactions participate a main role in [Zn(L 2)(phen)]-BSA binding process. Binding studies concerning the number of binding sites and apparent binding constant Kb were performed by fluorescence quenching method. The distance R between the donor (BSA) and acceptor (amino acid Schiff base complexes) has been obtained utilizing fluorescence resonant energy transfer (FRET). Furthermore, CD spectra were used to investigate the structural changes of the BSA molecule with the addition of amino acid Schiff base complexes. The results indicate that the interaction of amino acid Schiff base complexes with BSA leads to changes in the secondary structure of the protein. Fractional contents of the secondary structure of BSA ( fα, fβ, fturn and frandom) were calculated with and without amino acid Schiff base complexes utilizing circular dichroism spectroscopy. Our results clarified that amino acid Schiff base complexes could bind to BSA and be effectively transported and eliminated in the body, which could be a useful guideline for further drug

  20. Structure of Complexes of Lanthanides with N,N'-Dimethyl-3-Oxa-Glutaramic Acid

    Institute of Scientific and Technical Information of China (English)

    Huang Nian; Wang Jianchen; Zhang Ping; Sun Dazhi; Zhang Jing; Liu Tao

    2005-01-01

    A new stripping agent N,N-dimethyl-3-oxa-glutaramic Acid (DOGA) was used in TRPO process to simplify the TRPO process. The structures of the complexes of the DOGA with Eu(Ⅲ), Nd(Ⅲ), La(Ⅲ) were characterized with extended X-ray absorption fine structure spectroscopy (EXAFS), infrared spectra (IR) and mass spectra (MS). The molecular formula of the complexes of Eu(Ⅲ) and Nd(Ⅲ) is deduced to be M(DOGA)3, and only La(Ⅲ) can form the complex HM(DOGA)4 under condition of high consistency of the DOGA. The coordination number of Ln(Ⅲ) in the complexes is 8, and all of coordinated donor atoms are O atoms. For Eu(Ⅲ), Nd(Ⅲ), the coordination numbers of O atom in the first coordination shell is 6 and the average coordination bond lengths of Ln-O are 0.240 nm, 0.244 nm respectively, while the numbers of the second O shell are 2.4, and the average coordination bond lengths of Ln-O are 0.260 nm, 0.262 nm. For La(Ⅲ), the coordination numbers of O atom in the first coordination shell is 6 and the average coordination bond lengths of La-O are 0.258 nm, while the number of O atom in the second coordination shell is 4.4, and the average coordination bond length of La-O is 0.28 nm. The results of IR and MS show that there is no water coordinating with Ln(Ⅲ) in the complexes.

  1. Supramolecular Formation via Hydrogen Bonding in Copper and Nickel Complexes with 2-Hydroxynicotinic Acid

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Two complexes, Cu(HnicO)2 1 and Ni(HnicO)2(H2O)2 2 (H2nicO = 2-hydroxy- nicolinic acid), were synthesized by hydrothermal reactions and structurally characterized. Complex 1 crystallizes in monoclinic, space group P21/n, with a = 8.314(7), b = 6.275(4), c = 11.283(7) (A), β = 98.32(3)°, V = 582.5(7) (A)3, Z = 2, Mr = 339.74, Dc = 1.937 g/cm3, F(000) = 342, μ = 1.908 mm-1, S = 1.097, the final R = 0.0284 and wR = 0.0781 for 1177 observed reflections with I>2σ(I). Complex 2 crystallizes in monoclinic, space group P21/c, with a = 7.438(5), b = 12.22(1), c = 7.537(5) (A), β = 100.07(3)°, V = 674.3(8) (A)3, Z = 2, Mr = 370.95, Dc = 1.827 g/cm3, F(000) = 380, μ = 1.487 mm-1, S = 1.041, the final R = 0.0335 and wR = 0.0779 for 1202 observed reflections with I>2σ(I). There are extended 3D framework structures in complexes 1 and 2 due to the N-H…O and C-H…O hydrogen bonds. The copper atom in 1 has square planar coordination, while the nickel atom in 2 adopts octahedral coordination geometry. The TG curve shows that complex 2 is stable in solid state to 150 ℃.

  2. Cobalt (II)-EDTA complex as a new reductant for phosphomolybdic acid used for the assay of trazodone

    Indian Academy of Sciences (India)

    A V S S Prasad; C S P Sastry

    2003-02-01

    A new spectrophotometric method for the assay of trazodone (TZ) has been described. TZ forms a complex in stoichiometric proportions with phosphomolybdic acid. The released phosphomolybdic acid from the complex with acetone is reduced with a new reductant (cobalt nitrate-ethylenediamine tetra acetic acid) to molybdenum blue, which has maximum absorption at 840 nm. Beer's law limits, precision and accuracy of the methods are checked by the UV reference method. This method is found to be suitable for the assay of TZ in the presence of other ingredients that are usually present in tablets. Recoveries are almost quantitative.

  3. Solid-State Synthesis, Characterization, and Biological Activity of the Bioinorganic Complex of Aspartic Acid and Arsenic Triiodide

    Directory of Open Access Journals (Sweden)

    Guo-Qing Zhong

    2013-01-01

    Full Text Available The bioinorganic complex of aspartic acid and arsenic triiodide was synthesized by a solid-state reaction at room temperature. The formula of the complex is AsI3[HOOCCH2CH(NH2COOH]2.5. The crystal structure of the complex belongs to monoclinic system with lattice parameters: a=1.0019 nm, b=1.5118 nm, c=2.1971 nm, and β=100.28°. The infrared spectra can demonstrate the complex formation between the arsenic ion and aspartic acid, and the complex may be a dimer with bridge structure. The result of primary biological test indicates that the complex possesses better biological activity for the HL-60 cells of the leukemia than arsenic triiodide.

  4. Synthesis, structural characterization and biological studies of some nalidixic acid-metal complexes: Metalloantibiotic complexes of some divalent and trivalent metal ions

    Science.gov (United States)

    Al-Khodir, Fatima A. I.; Refat, Moamen S.

    2015-08-01

    This article describes the synthesis, characterization, computational and biological assessments of some divalent and trivalent metal (Ca(II), Fe(III), Pd(II) and Au(III)) complexes of nalidixic acid (nixH). The structures of these complexes were assigned using elemental analyses and spectral measurements e.g., IR, Raman, 1H NMR, 13C NMR and electronic techniques. These results indicated that, nalidixic acid reacts as a bidentate ligand bound to the metal ion through the oxygen atoms of carbonyl and carboxylate groups. The molar conductance measurements of the complexes in DMSO correspond to be non-electrolyte nature. Thus, these complexes may be formulated as [Ca(nix)(Cl)(H2O)3]. H2O, [Fe(nix)(Cl)2(H2O)2]·3H2O, [Pd(nix)(Cl)(H2O)] and [Au(nix)(Cl)2]. Base on the Coats-Redfern and Horowitz-Metzeger methods, the kinetic thermodynamic parameters (E∗, ΔS∗, ΔH∗ and ΔG∗) of the thermal decomposition reactions have been calculated from thermogravimetric curves of TG and DTG. The nano-scale range of the nalidixic acid complexes have been discussed using X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) analyzer. The computational studies for the synthesized complexes have been estimated.

  5. From ligand to complexes. Part 2. Remarks on human immunodeficiency virus type 1 integrase inhibition by beta-diketo acid metal complexes.

    Science.gov (United States)

    Bacchi, Alessia; Biemmi, Mariano; Carcelli, Mauro; Carta, Fabrizio; Compari, Carlotta; Fisicaro, Emilia; Rogolino, Dominga; Sechi, Mario; Sippel, Martin; Sotriffer, Christoph A; Sanchez, Tino W; Neamati, Nouri

    2008-11-27

    Previously, we synthesized a series of beta-diketo acid metal complexes as novel HIV-1 integrase (IN) inhibitors (J. Med. Chem. 2006, 46, 4248-4260). Herein, a further extension of this study is reported. First, detailed docking studies were performed in order to investigate the mode of binding in the active site of the free ligands and of their metal complexes. Second, a series of potentiometric measurements were conducted for two diketo acids chosen as model ligands, with Mn(2+) and Ca(2+), in order to outline a speciation model. Third, we designed and synthesized a new set of complexes with different stoichiometries and tested them in an in vitro assay specific for IN. Finally, we obtained the first X-ray structure of a metal complex with HIV-1 IN inhibition activity. Analysis of these results supports the hypothesis that the diketo acids could act as complexes and form complexes with the metal ions on the active site of the enzyme.

  6. Lactic acid bacteria contribution to gut microbiota complexity: lights and shadows.

    Directory of Open Access Journals (Sweden)

    Enrica ePessione

    2012-06-01

    Full Text Available Lactic Acid Bacteria (LAB are ancient organisms that cannot biosynthesize functional cytochromes, and cannot get ATP from respiration. Besides sugar fermentation, they evolved electrogenic decarboxylations and ATP-forming deiminations. The right balance between sugar fermentation and decarboxylation/deimination ensures buffered environments thus enabling LAB to survive in human gastric trait and colonize gut. A complex molecular cross-talk between LAB and host exists. LAB moonlight proteins are made in response to gut stimuli and promote bacterial adhesion to mucosa and stimulate immune cells. Similarly, when LAB are present, human enterocytes activate expression of specific genes only. Furthermore, LAB antagonistic relationships with other microorganisms constitutes the basis for their antiinfective role. Histamine and tyramine are LAB bioactive catabolites that act on the CNS, causing hypertension and allergies. Nevertheless, some LAB biosynthesize both GABA, that has relaxing effect on gut smooth muscles, and beta-phenylethylamine, that controls satiety and mood. Since LAB have reduced amino acid biosynthetic abilities, they developed a sophisticated proteolytic system, that is also involved in antihypertensive and opiod peptide generation from milk proteins.Short-chain fatty acids are glycolytic and phosphoketolase end-products, regulating epithelial cellproliferation and differentiation. Nevertheless, they constitute a supplementary energy source for the host, causing weight gain. Human metabolism can also be affected by anabolic LAB products such as conjugated linoleic acids (CLA. Some CLA isomers reduce cancer cell viability and ameliorate insulin resistance, while others lower the HDL/LDL ratio and modify eicosanoid production, with detrimental health effects.A further appreciated LAB feature is the ability to fix selenium into seleno-cysteine Thus opening interesting perspectives for their utilization as antioxidant nutraceutical

  7. Synthesis and Crystal Structure of a Lanthanum(III) Complex with Chelidamic Acid

    Institute of Scientific and Technical Information of China (English)

    ZOU Jian-Ping; ZHOU Guo-Wei; GUO Guo-Cong; YAN Liu-Shui; ZENG Gui-Sheng; HUANG Jin-Shun

    2008-01-01

    A new lanthanum complex, (H3O)2[La(C7H3NO5)2(H2O)2]2·3(H2O) or (H3O)2[La(HChel)2(H2O)2]2·3(H2O) 1 (H3Chel = 4-hydroxypyridine-2,6-dicarboxylic(chelidamic) acid), has been prepared by the hydrothermal reaction, and its crystal structure was determined based on single-crystal diffraction data. Compound 1 crystallizes in triclinic, space group P with a = 9.6939(19), b = 10.176(2), c = 11.502(2) (A), α = 111.52(3), β = 93.74(3), γ = 103.33(3)°, V = 1013.0(3) (A)3, Dc = 1.912 g/cm3, Z = 1, Mr = 1166.40, μ = 2.188 mm-1, λ(MoKα) = 0.71073 (A) and F(000) = 574. The final R = 0.0342 and wR = 0.0737 for 4080 observed reflections with I > 2σ(I), and R = 0.0429 and wR = 0.0772 for all data. Compound 1 contains two lanthanum ions, four chelidamic acid ligands, four coordinated water molecules, two hydroniums, and three discrete water molecules. The LaIII atom is ten-coordinated by four oxygen and two nitrogen atoms from two tridentate chelating chelidamic acid ligands, two carboxylic oxygen atoms from an adjacent chelidamic acid ligand and two coordinated water molecules, leading to a distorted dodecahedral geometry. A three-dimensional network is formed by H-bonds.

  8. Synthesis of New Chiral Benzimidazolylidene–Rh Complexes and Their Application in Asymmetric Addition Reactions of Organoboronic Acids to Aldehydes

    Directory of Open Access Journals (Sweden)

    Weiping He

    2016-09-01

    Full Text Available A series of novel chiral N-heterocyclic carbene rhodium complexes (NHC–Rh based on benzimidazole have been prepared, and all of the NHC–Rh complexes were fully characterized by NMR and mass spectrometry. These complexes could be used as catalysts for the asymmetric 1,2-addition of organoboronic acids to aldehydes, affording chiral diarylmethanols with high yields and moderate enantioselectivities.

  9. Gradient Elution Moving Boundary Electrophoresis Enables Rapid Analysis of Acids in Complex Biomass-Derived Streams

    Energy Technology Data Exchange (ETDEWEB)

    Munson, Matthew S.; Karp, Eric M.; Nimlos, Claire T.; Salit, Marc; Beckham, Gregg T.

    2016-12-05

    Biomass conversion processes such as pretreatment, liquefaction, and pyrolysis often produce complex mixtures of intermediates that are a substantial challenge to analyze rapidly and reliably. To characterize these streams more comprehensively and efficiently, new techniques are needed to track species through biomass deconstruction and conversion processes. Here, we present the application of an emerging analytical method, gradient elution moving boundary electrophoresis (GEMBE), to quantify a suite of acids in a complex, biomass-derived streams from alkaline pretreatment of corn stover. GEMBE offers distinct advantages over common chromatography-spectrometry analytical approaches in terms of analysis time, sample preparation requirements, and cost of equipment. As demonstrated here, GEMBE is able to track 17 distinct compounds (oxalate, formate, succinate, malate, acetate, glycolate, protocatechuate, 3-hydroxypropanoate, lactate, glycerate, 2-hydroxybutanoate, 4-hydroxybenzoate, vanillate, p-coumarate, ferulate, sinapate, and acetovanillone). The lower limit of detection was compound dependent and ranged between 0.9 and 3.5 umol/L. Results from GEMBE were similar to recent results from an orthogonal method based on GCxGC-TOF/MS. Overall, GEMBE offers a rapid, robust approach to analyze complex biomass-derived samples, and given the ease and convenience of deployment, may offer an analytical solution for online tracking of multiple types of biomass streams.

  10. Pickering Emulsion Gels Prepared by Hydrogen-Bonded Zein/Tannic Acid Complex Colloidal Particles.

    Science.gov (United States)

    Zou, Yuan; Guo, Jian; Yin, Shou-Wei; Wang, Jin-Mei; Yang, Xiao-Quan

    2015-08-26

    Food-grade colloidal particles and complexes, which are formed via modulation of the noncovalent interactions between macromolecules and natural small molecules, can be developed as novel functional ingredients in a safe and sustainable way. For this study was prepared a novel zein/tannic acid (TA) complex colloidal particle (ZTP) based on the hydrogen-bonding interaction between zein and TA in aqueous ethanol solution by using a simple antisolvent approach. Pickering emulsion gels with high oil volume fraction (φ(oil) > 50%) were successfully fabricated via one-step homogenization. Circular dichroism (CD) and small-angle X-ray scattering (SAXS) measurements, which were used to characterize the structure of zein/TA complexes in ethanol solution, clearly showed that TA binding generated a conformational change of zein without altering their supramolecular structure at pH 5.0 and intermediate TA concentrations. Consequently, the resultant ZTP had tuned near neutral wettability (θ(ow) ∼ 86°) and enhanced interfacial reactivity, but without significantly decreased surface charge. These allowed the ZTP to stabilize the oil droplets and further triggered cross-linking to form a continuous network among and around the oil droplets and protein particles, leading to the formation of stable Pickering emulsion gels. Layer-by-layer (LbL) interfacial architecture on the oil-water surface of the droplets was observed, which implied a possibility to fabricate hierarchical interface microstructure via modulation of the noncovalent interaction between hydrophobic protein and natural polyphenol.

  11. Aspartic acid complexation of Am(III) and U(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Saito, A.; Choppin, G.R.

    1984-01-01

    Stability constants of Am(III) and U(VI) with L-aspartic acid have been determined at pH 8.00 by means of the solvent extraction technique. It was found that Am(III) forms 1:1 and 1:2 complexes while U(VI) formed only the 1:1 complex under these conditions. The stability constants were: Am/sup +3/: I = 0.10 M; log ..beta../sub 1/ = 4.81 +- 0.03, log ..beta../sub 2/ = 6.75 +- 0.03 I = 0.70 M; log ..beta../sub 1/ = 4.53 +- 0.08 log ..beta../sub 2/ = 6.65 +- 0.06 UO/sup +2//sub 2/: I = 0.70 M; log ..beta../sub 1/ = 3.32 +- 0.04. Comparison of these stability constants with corresponding values of some dicarboxylate ligands suggests that at pH 8 the binding of Am/sup +3/ and UO/sup +2//sub 2/ involves both carboxylates. In the Am-aspartate complex, the data indicate the possibility of weak interaction between the Am/sup +3/ and the amino group.

  12. Enantioselective Hydrolysis of Amino Acid Esters Promoted by Bis(β-cyclodextrin) Copper Complexes.

    Science.gov (United States)

    Xue, Shan-Shan; Zhao, Meng; Ke, Zhuo-Feng; Cheng, Bei-Chen; Su, Hua; Cao, Qian; Cao, Zhen-Kun; Wang, Jun; Ji, Liang-Nian; Mao, Zong-Wan

    2016-02-26

    It is challenging to create artificial catalysts that approach enzymes with regard to catalytic efficiency and selectivity. The enantioselective catalysis ranks the privileged characteristic of enzymatic transformations. Here, we report two pyridine-linked bis(β-cyclodextrin) (bisCD) copper(II) complexes that enantioselectively hydrolyse chiral esters. Hydrolytic kinetic resolution of three pairs of amino acid ester enantiomers (S1-S3) at neutral pH indicated that the "back-to-back" bisCD complex CuL(1) favoured higher catalytic efficiency and more pronounced enantioselectivity than the "face-to-face" complex CuL(2). The best enantioselectivity was observed for N-Boc-phenylalanine 4-nitrophenyl ester (S2) enantiomers promoted by CuL(1), which exhibited an enantiomer selectivity of 15.7. We observed preferential hydrolysis of L-S2 by CuL(1), even in racemic S2, through chiral high-performance liquid chromatography (HPLC). We demonstrated that the enantioselective hydrolysis was related to the cooperative roles of the intramolecular flanking chiral CD cavities with the coordinated copper ion, according to the results of electrospray ionization mass spectrometry (ESI-MS), inhibition experiments, rotating-frame nuclear Overhauser effect spectroscopy (ROESY), and theoretical calculations. Although the catalytic parameters lag behind the level of enzymatic transformation, this study confirms the cooperative effect of the first and second coordination spheres of artificial catalysts in enantioselectivity and provides hints that may guide future explorations of enzyme mimics.

  13. Molecular spectrum of lanthanide complexes with 2,3-dichlorobenzoic acid and 2,2-bipyridine.

    Science.gov (United States)

    He, Shu-Mei; Sun, Shu-Jing; Zheng, Jun-Ru; Zhang, Jian-Jun

    2014-04-05

    With 2,3-dichlorobenzoic acid as the first ligands and 2,2'-bipyridine as the second ligands, the lanthanide complexes [Ln(2,3-DClBA)3bipy]2 [Ln=Nd(a), Sm(b), Eu(c), Tb(d), Dy(e), Ho(f)] have been synthesized. By using Infrared (IR) and Raman (R) spectra, the characteristics of the groups can be identified. The bands of lanthanide complexes have been analyzed and attributed, and clearly demonstrated with the use of the complementarity of IR and R. The experiment reveals that the bands of complexes are affected by lanthanide elements (Ln). The frequency of stretching vibration and breathing vibration of ring, together with the stretching vibration of the carbonyl group (νCO), tends to be rising as the atomic number of lanthanide increasing. Meanwhile, crystallography data demonstrate that the six carbonyl groups have different bond length and bond angle, which can lead to different vibration frequency. The second derivatives of IR show that there are multiple vibration frequencies existing in the symmetrical stretching vibration of the carbonyl group (νsCO). Therefore the second derivative of IR spectrum is a characteristic band of different coordination modes of carbonyl group.

  14. Enantioselective Hydrolysis of Amino Acid Esters Promoted by Bis(β-cyclodextrin) Copper Complexes

    Science.gov (United States)

    Xue, Shan-Shan; Zhao, Meng; Ke, Zhuo-Feng; Cheng, Bei-Chen; Su, Hua; Cao, Qian; Cao, Zhen-Kun; Wang, Jun; Ji, Liang-Nian; Mao, Zong-Wan

    2016-02-01

    It is challenging to create artificial catalysts that approach enzymes with regard to catalytic efficiency and selectivity. The enantioselective catalysis ranks the privileged characteristic of enzymatic transformations. Here, we report two pyridine-linked bis(β-cyclodextrin) (bisCD) copper(II) complexes that enantioselectively hydrolyse chiral esters. Hydrolytic kinetic resolution of three pairs of amino acid ester enantiomers (S1–S3) at neutral pH indicated that the “back-to-back” bisCD complex CuL1 favoured higher catalytic efficiency and more pronounced enantioselectivity than the “face-to-face” complex CuL2. The best enantioselectivity was observed for N-Boc-phenylalanine 4-nitrophenyl ester (S2) enantiomers promoted by CuL1, which exhibited an enantiomer selectivity of 15.7. We observed preferential hydrolysis of L-S2 by CuL1, even in racemic S2, through chiral high-performance liquid chromatography (HPLC). We demonstrated that the enantioselective hydrolysis was related to the cooperative roles of the intramolecular flanking chiral CD cavities with the coordinated copper ion, according to the results of electrospray ionization mass spectrometry (ESI-MS), inhibition experiments, rotating-frame nuclear Overhauser effect spectroscopy (ROESY), and theoretical calculations. Although the catalytic parameters lag behind the level of enzymatic transformation, this study confirms the cooperative effect of the first and second coordination spheres of artificial catalysts in enantioselectivity and provides hints that may guide future explorations of enzyme mimics.

  15. Complexes between ovalbumin nanoparticles and linoleic acid: Stoichiometric, kinetic and thermodynamic aspects.

    Science.gov (United States)

    Sponton, Osvaldo E; Perez, Adrián A; Carrara, Carlos R; Santiago, Liliana G

    2016-11-15

    Stoichiometric, kinetic and thermodynamic aspects of complex formation between heat-induced aggregates of ovalbumin (ovalbumin nanoparticles, OVAn) and linoleic acid (LA) were evaluated. Extrinsic fluorescence data were fitted to modified Scatchard model yielding the following results: n: 49±2 LA molecules bound per OVA monomer unit and Ka: 9.80±2.53×10(5)M. Kinetic and thermodynamic properties were analyzed by turbidity measurements at different LA/OVA monomer molar ratios (21.5-172) and temperatures (20-40°C). An adsorption approach was used and a pseudo-second-order kinetics was found for LA-OVAn complex formation. This adsorption process took place within 1h. Thermodynamic parameters indicated that LA adsorption on OVAn was a spontaneous, endothermic and entropically-driven process, highlighting the hydrophobic nature of the LA and OVAn interaction. Finally, Atomic Force Microscopy imaging revealed that both OVAn and LA-OVAn complexes have a roughly rounded form with size lower than 100nm.

  16. Synthesis and Crystal Structure of a New Copper(Ⅱ) Complex with 4-Cyanobenzoic Acid

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A new Cu(Ⅱ) complex [Cu(4-cba)(l,10-phen)(H2O)2](NO3) (4-Hcba = 4-cyanobenzoic acid) has been synthesized by solvothermal reaction in an ethanol/water mixed solution at 100℃ and structurally characterized by single-crystal X-ray diffraction. Crystallographic data: C20H16CuN4O7, Mr= 487.91, triclinic, space group P1, a = 7.8420(2), b = 9.1070(2), c = 15.1140(6) A,α=76.889(9), β = 81.332( 11 ), γ = 74.844(11 )°, V = 1009.89(5) A3, Z = 2, Dc = 1.605 g/cm3, F(000)=498,μ=1.134 mm-1,the final R = 0.0379 and wR = 0.0865 for 2977 observed reflections with I > 2σ(Ⅰ).The Cu(Ⅱ) atom is coordinated by two terminal water molecules, one chelating 1,10-phen molecule and one monodentate 4-cba ligand to form a slightly distorted square pyramid. The title complex molecules are connected through hydrogen bonds and π-π stacking interactions to generate a 2D layered network. The thermogravimetric analysis of the title complex has also been discussed.

  17. New copper(II) complexes with dopamine hydrochloride and vanillymandelic acid: Spectroscopic and thermal characterization

    Science.gov (United States)

    Mohamed, Gehad G.; Nour El-Dien, F. A.; El-Nahas, R. G.

    2011-10-01

    The dopamine derivatives participate in the regulation of wide variety of physiological functions in the human body and in medication life. Increase and/or decrease in the concentration of dopamine in human body reflect an indication for diseases such as Schizophrenia and/or Parkinson diseases. The Cu(II) chelates with coupled products of dopamine hydrochloride (DO.HCl) and vanillymandelic acid (VMA) with 4-aminoantipyrine (4-AAP) are prepared and characterized. Different physico-chemical techniques namely IR, magnetic and UV-vis spectra are used to investigate the structure of these chelates. Cu(II) forms 1:1 (Cu:DO) and 1:2 (Cu:VMA) chelates. DO behave as a uninegative tridentate ligand in binding to the Cu(II) ion while VMA behaves as a uninegative bidentate ligand. IR spectra show that the DO is coordinated to the Cu(II) ion in a tridentate manner with ONO donor sites of the phenolic- OH, -NH and carbonyl- O, while VMA is coordinated with OO donor sites of the phenolic- OH and -NH. Magnetic moment measurements reveal the presence of Cu(II) chelates in octahedral and square planar geometries with DO and VMA, respectively. The thermal decomposition of Cu(II) complexes is studied using thermogravimetric (TG) and differential thermal analysis (DTA) techniques. The activation thermodynamic parameters, such as, energy of activation, enthalpy, entropy and free energy change of the complexes are evaluated and the relative thermal stability of the complexes are discussed.

  18. Clay-Nucleic Acid Complexes: Characteristics and Implications for the Preservation of Genetic Material in Primeval Habitats

    Science.gov (United States)

    Franchi, Marco; Bramanti, Emilia; Morassi Bonzi, Laura; Luigi Orioli, Pier; Vettori, Cristina; Gallori, Enzo

    1999-05-01

    The equilibrium adsorption of three nucleic acids: chromosomal DNA, supercoiled plasmid DNA, and 25S rRNA, on the clay minerals, montmorillonite (M) and kaolinite (K), were studied. Adsorption of the nucleic acid on the clays was rapid and maximal after 90 min of contact time. Chromosomal DNA was adsorbed to a greater extent than plasmid DNA and RNA, and the adsorption was also greater on M than on K. Adsorption isotherms were of the L type, and a plateau was reached with all the complexes, with the exception of chromosomal DNA adsorbed on M. To determine where nucleic acids are adsorbed on clay minerals and the nature of the interaction, complexes were studied by X-ray diffraction (X-RD), electron microscopy, and Fourier transform infrared (FT-IR) spectroscopy. X-RD showed that nucleic acids did not penetrate the clay, indicating that the adsorption occurred primarily on the external surfaces of clay particles, as also suggested by electron microscopy observations. FT-IR spectra of clay-tightly bound nucleic acid complexes showed absorption bands that indicate a variation of the nucleic acids status as a consequence of their adsorption on clay. Data obtained suggested that the formation of clay-nucleic acid complex could have an important role in the preservation of genetic material in primeval habitats.

  19. Characterisation and application of new carboxylic acid-functionalised ruthenium complexes as dye-sensitisers for solar cells

    DEFF Research Database (Denmark)

    Duprez, Virginie; Biancardo, Matteo; Krebs, Frederik C

    2007-01-01

    A series of ruthenium complexes with and without TiO2, anchoring carboxylic acid groups have been synthesised and characterised using nuclear magnetic resonance (NMR), UV-vis and luminescence. These complexes were adsorbed on thin films of the wide band-gap semiconductor anatase and were tested a......',2"] terpyridine-4'-carboxylic acid with a maximum output power similar to 0.016mWcm(-2) under illumination at 100mWcm(-2) AM1.5 and efficiencies 3 times higher than the symmetric complexes. (c) 2006 Elsevier B.V. All rights reserved....

  20. Protonation equilibrium and hydrogen production by a dinuclear cobalt-hydride complex reduced by cobaltocene with trifluoroacetic acid.

    Science.gov (United States)

    Mandal, Sukanta; Shikano, Shinya; Yamada, Yusuke; Lee, Yong-Min; Nam, Wonwoo; Llobet, Antoni; Fukuzumi, Shunichi

    2013-10-16

    A dinuclear Co complex with bis(pyridyl)pyrazolato (bpp(-)) and terpyridine (trpy) ligands, [Co(III)2(trpy)2(μ-bpp)(OH)(OH2)](4+) (1(4+)), undergoes three-electron reduction by cobaltocene in acetonitrile to produce 1(+), which is in the protonation equilibrium with the Co(II)Co(III)-hydride complex, and the further protonation of the hydride by trifluoroacetic acid yields hydrogen quantitatively. The kinetic study together with the detection of the Co(II)Co(III)-hydride complex revealed the mechanism of the hydrogen production by the reaction of 1(+) with trifluoroacetic acid.

  1. X-ray studies of crystalline complexes involving amino acids and peptides. XLIV. Invariant features of supramolecular association and chiral effects in the complexes of arginine and lysine with tartaric acid.

    Science.gov (United States)

    Selvaraj, M; Thamotharan, S; Roy, Siddhartha; Vijayan, M

    2007-06-01

    The tartaric acid complexes with arginine and lysine exhibit two stoichiometries depending upon the ionization state of the anion. The structures reported here are DL-argininium DL-hydrogen tartrate, bis(L-argininium) L-tartrate, bis(DL-lysinium) DL-tartrate monohydrate, L-lysinium D-hydrogen tartrate and L-lysinium L-hydrogen tartrate. During crystallization, L-lysine preferentially interacts with D-tartaric acid to form a complex when DL-tartaric acid is used in the experiment. The anions and the cations aggregate into separate alternating layers in four of the five complexes. In bis(L-argininium) L-tartrate, the amino acid layers are interconnected by individual tartrate ions which do not interact among themselves. The aggregation of argininium ions in the DL- and the L-arginine complexes is remarkably similar, which is in turn similar to those observed in other dicarboxylic acid complexes of arginine. Thus, argininium ions have a tendency to assume similar patterns of aggregation, which are largely unaffected by a change in the chemistry of partner molecules such as the introduction of hydroxyl groups or a change in chirality or stoichiometry. On the contrary, the lysinium ions exhibit fundamentally different aggregation patterns in the DL-DL complexes on the one hand and L-D and L-L complexes on the other. Interestingly, the pattern in the L-D complex is similar to that in the L-L complex. The lysinium ions in the DL-DL complex exhibit an aggregation pattern similar to those observed in the DL-lysine complexes involving other dicarboxylic acids. Thus, the effect of change in the chirality of a subset of the component complexes could be profound or marginal, in an unpredictable manner. The relevant crystal structures appear to indicate that the preference of L-lysine for D-tartaric acid is perhaps caused by chiral discrimination resulting from the amplification of a small energy difference.

  2. Novel lanthanide complexes constructed from 3, 4-dimethoxybenzoic acid: crystal structures, spectrum and thermochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Xiao-Xia; Wu, Jun-Chen [Testing and Analysis Center, Hebei Normal University, Shijiazhuang 050024 (China); College of Chemistry & Material Science, Hebei Normal University, Shijiazhuang 050024 (China); Ren, Ning, E-mail: ningren9@163.com [College of Chemical engineering & Material, Handan College, Handan 056005 (China); Zhao, Chun-Li [Raoyang High School of Hebei, Raoyang 053900 (China); Zhang, Jian-Jun, E-mail: jjzhang6@126.com [Testing and Analysis Center, Hebei Normal University, Shijiazhuang 050024 (China); College of Chemistry & Material Science, Hebei Normal University, Shijiazhuang 050024 (China); Zong, Guang-Cai; Gao, Jie [Testing and Analysis Center, Hebei Normal University, Shijiazhuang 050024 (China); College of Chemistry & Material Science, Hebei Normal University, Shijiazhuang 050024 (China)

    2015-09-10

    Graphical abstract: Four novel lanthanide coordination polymers [Ln(3,4-DMOBA){sub 3}(H{sub 2}O){sub 2}]·H{sub 2}O·C{sub 2}H{sub 5}OH (Ln = Sm(1), Tb(2), Dy(3), Ho(4); 3,4-DMOBA = 3, 4-dimethoxybenzoate) have been hydrothermal synthesized and characterized. Single crystal structures indicates 1 D stucture of the title complexes are linked by hydrogen bonds to form a three-dimensional (3-D) structure. Complex 2 exhibits the characteristic emission of Tb{sup 3+} ion({sup 5}D{sub 4} → {sup 7}F{sub 6-3}). The investigation of TG-FTIR and IR spectra of the evolved gases shows uncoordinated water and ethanol molecules tend to lose firstly, and then 3,4-DMOBA ligands begin to decompose. - Highlights: • Four lanthanide coordination polymers were synthesized and characterized. • 1-D chain structures of the title complexes are are linked by hydrogen bonds to form a 3-D structures. • Thermal decomposition processes of the title complexes were studied using TG-FTIR techniques. • IR spectra of evolved gases in thermal decomposition process were obtained and analyzed. - Abstract: Four novel lanthanide complexes [Ln(3,4-DMOBA){sub 3}(H{sub 2}O){sub 2}]·H{sub 2}O·C{sub 2}H{sub 5}OH (Ln = Sm(1), Tb(2), Dy(3), Ho(4); 3,4-DMOBA = 3, 4-dimethoxybenzoate) have been hydrothermal synthesized and characterized. Structural analyses reveal that adjacent lanthanide ions are connected by 3,4-DMOBA ligands adopting bridging bidentate mode to generate one-dimensional (1-D) structure with the uncoordinated water and ethanol molecules. 1-D structures are linked by hydrogen bonds to form a three-dimensional (3-D) structure, which is rarely observed in lanthanide carboxylic acids complexes. Under the radiation of UV light, complex 2 exhibits the characteristic emission of Tb{sup 3+} ion ({sup 5}D{sub 4} → {sup 7}F{sub 6-3}). The thermal decomposition mechanism is investigated by TG-FTIR technology. IR spectra of the evolved gases show that the uncoordinated water and ethanol

  3. Sphingolipid biosynthesis upregulation by TOR complex 2-Ypk1 signaling during yeast adaptive response to acetic acid stress.

    Science.gov (United States)

    Guerreiro, Joana F; Muir, Alexander; Ramachandran, Subramaniam; Thorner, Jeremy; Sá-Correia, Isabel

    2016-12-01

    Acetic acid-induced inhibition of yeast growth and metabolism limits the productivity of industrial fermentation processes, especially when lignocellulosic hydrolysates are used as feedstock in industrial biotechnology. Tolerance to acetic acid of food spoilage yeasts is also a problem in the preservation of acidic foods and beverages. Thus understanding the molecular mechanisms underlying adaptation and tolerance to acetic acid stress is increasingly important in industrial biotechnology and the food industry. Prior genetic screens for Saccharomyces cerevisiae mutants with increased sensitivity to acetic acid identified loss-of-function mutations in the YPK1 gene, which encodes a protein kinase activated by the target of rapamycin (TOR) complex 2 (TORC2). We show in the present study by several independent criteria that TORC2-Ypk1 signaling is stimulated in response to acetic acid stress. Moreover, we demonstrate that TORC2-mediated Ypk1 phosphorylation and activation is necessary for acetic acid tolerance, and occurs independently of Hrk1, a protein kinase previously implicated in the cellular response to acetic acid. In addition, we show that TORC2-Ypk1-mediated activation of l-serine:palmitoyl-CoA acyltransferase, the enzyme complex that catalyzes the first committed step of sphingolipid biosynthesis, is required for acetic acid tolerance. Furthermore, analysis of the sphingolipid pathway using inhibitors and mutants indicates that it is production of certain complex sphingolipids that contributes to conferring acetic acid tolerance. Consistent with that conclusion, promoting sphingolipid synthesis by adding exogenous long-chain base precursor phytosphingosine to the growth medium enhanced acetic acid tolerance. Thus appropriate modulation of the TORC2-Ypk1-sphingolipid axis in industrial yeast strains may have utility in improving fermentations of acetic acid-containing feedstocks.

  4. Correlations and predictions of carboxylic acid pKa values using intermolecular structure and properties of hydrogen-bonded complexes.

    Science.gov (United States)

    Tao, Li; Han, Jun; Tao, Fu-Ming

    2008-01-31

    Density functional theory calculations have been preformed on a series of hydrogen-bonded complexes of substituted aliphatic and aromatic carboxylic acids with ammonia. Molecular properties, particularly those related to hydrogen bonding, have been carefully examined for their interdependence as well as dependence on the acidity of the acid. The bond length and stretching frequency of the hydroxyl group and the hydrogen-bond length and energy of the complex are shown to be highly correlated with each other and are linearly correlated with available literature pKa values of the carboxylic acids. The linear correlations resulting from the fit to the available pKa values can be used to predict the pKa values of similar carboxylic acids. The pKa values so predicted using the different molecular properties are highly consistent and in good agreement with the literature values. This study suggests that calculated molecular properties of hydrogen-bonded complexes allow effective and systematic prediction of pKa values for a large range of organic acids using the established linear correlations. This approach is unique in its capability to determine the acidity of a particular functional group or the local acidity within a large molecular system such as a protein.

  5. Preparation of highly purified pinolenic acid from pine nut oil using a combination of enzymatic esterification and urea complexation.

    Science.gov (United States)

    No, Da Som; Zhao, Ting Ting; Kim, Yangha; Yoon, Mi-Ra; Lee, Jeom-Sig; Kim, In-Hwan

    2015-03-01

    Pinolenic acid (PLA) is a polyunsaturated fatty acid of plant origin. PLA has been successfully enriched according to a two-step process involving lipase-catalysed esterification and urea complexation. For the first step, the fatty acids present in pine nut oil were selectively esterified with lauryl alcohol using Candida rugosa lipase. Under the optimum conditions of 0.1% enzyme loading, 10% additional water, and 15 °C, PLA was enriched up to 43 mol% from an initial value of 13 mol% in the pine nut oil. For the second step, the PLA-enriched fraction from the first step was subjected to a urea complexation process. In this way, PLA enrichments with purities greater than 95 mol% were obtained at urea to fatty acid ratios greater than 3:1 (wt/wt), and 100% pure PLA was produced at a urea to fatty acid ratio of 5:1 with an 8.7 mol% yield.

  6. Effect of fatty acids complexed with polyethyleneimine on the flow curves of TiO2 nanoparticle/toluene suspensions

    Directory of Open Access Journals (Sweden)

    Motoyuki Iijima

    2016-09-01

    Full Text Available A series of polyethyleneimine (PEI–fatty acid complexes using oleic acid (OA, isostearic acid (ISA, and stearic acid (SA were prepared through a simple process. While PEI was not soluble in toluene, the complex with OA and ISA became soluble when its additive content was greater than 5 mol% based on the ethyleneimine (EI unit of PEI. PEI–SA had similar solubility in toluene when more than 5 mol% of SA was added; however, the complex precipitated when the additive ratio of SA was increased to 40 mol%. The effect of fatty acid of PEI complexes on their TiO2 nanoparticle adsorption properties and the flow curves of TiO2 nanoparticle/toluene suspension was then studied using PEI complexed with 30 mol% of fatty acids. Surprisingly, while PEI–OA and PEI–ISA complexes effectively adsorbed on TiO2 nanoparticles until saturation, the amount of adsorbed PEI–SA increased continuously. Comparing the flow curves of TiO2/toluene suspensions under 1.4 mg/m2 addition of PEI–fatty acid complexes, where PEI–OA and PEI–ISA were under saturated adsorption, it was confirmed that PEI–OA effectively stabilizes TiO2 nanoparticles in toluene without imparting thixotropic properties up to 30 vol%, while the suspensions with PEI–SA and PEI–ISA were solidified at lower volume contents and had high thixotropic properties.

  7. Novel one-dimensional lanthanide acrylic acid complexes: an alternative chain constructed by hydrogen bonding

    Science.gov (United States)

    Li, Hui; Hu, Chang Wen

    2004-12-01

    Novel one-dimensional (1D) chains of three lanthanide complexes La(L 1) 3(CH 3OH)]·CH 3OH (L 1=(E)-3-(2-hydroxyl-phenyl)-acrylic acid) 1, La(L 2) 3(H 2O) 2]·2.75H 2O (L 2=(E)-3-(3-hydroxyl-phenyl)-acrylic acid) 2, and La(L 3) 3(CH 3OH) 2(H 2O)]·CH 3OH (L 3=(E)-3-(4-hydroxyl-phenyl)-acrylic acid) 3 are reported. The crystal structure data are as follows for 1: C 29H 29LaO 11, monoclinic, P2 1/ n, a=15.4289(12) Å, b=7.9585(6) Å, c=23.041(2) Å, β=99.657(2)°, Z=4, R1=0.0637, w R2=0.0919; for 2: C 27H 30.50LaO 13.75, triclinic, P-1, a=8.4719(17) Å, b=13.719(3) Å, c=14.570(3) Å, α=62.19(3)°, β=99.657(2)°, γ=78.22(3)°, Z=2, R1=0.0384, w R2=0.0820; and for 3: C 30H 35LaO 13, monoclinic, P2(1)/ c, a=9.5667(6) Å, b=24.3911(15) Å, c=14.0448(9) Å, β=109.245(2)°, Z=4, R1=0.0374, w R2=0.0630. All the three structure data were collected using graphite monochromated molybdenum Kα radiation and refined using full-matrix least-squares techniques on F 2. These structures show that four kinds of the carboxylato bridge modes are included in these chains to link the La(III) ions. It is the first time that it has been found that the intra-chain hydrogen bonding can construct an alternative chain even, when the coordination bridge mode is the same along the chain (complex 2). There are 2D and 3D hydrogen bonding in the crystal lattices of complexes 1- 3.

  8. Specific chiral sensing of amino acids using induced circularly polarized luminescence of bis(diimine)dicarboxylic acid europium(III) complexes.

    Science.gov (United States)

    Okutani, Kazuhiro; Nozaki, Koichi; Iwamura, Munetaka

    2014-06-02

    The circularly polarized luminescence (CPL) from [Eu(pda)2](-) (pda = 1,10-phenanthroline-2,9-dicarboxylic acid) and [Eu(bda)2](-) (bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) in aqueous solutions containing various amino acids was investigated. The europium(III) complexes exhibited bright-red luminescence assignable to the f-f transition of the Eu(III) ion when irradiated with UV light. Although the luminescence was not circularly polarized in the solid state or in aqueous solutions, in accordance with the achiral crystal structure, the complexes exhibited detectable induced CPL (iCPL) in aqueous solutions containing chiral amino acids. In the presence of L-pyrrolidonecarboxylic acid, both [Eu(pda)2](-) and [Eu(bda)2](-) showed similar iCPL intensity (glum ∼ 0.03 for the (5)D0 → (7)F1 transition at 1 mol·dm(-3) of the amino acid). On the other hand, in the presence of L-histidine or L-arginine, [Eu(pda)2](-) exhibited intense CPL (glum ∼ 0.08 for the (5)D0 → (7)F1 transition at 0.10 mol·dm(-3) of the amino acid), whereas quite weak CPL was observed for [Eu(bda)2](-) under the same conditions (glum amino acids, [Eu(pda)2](-) was found to be a good chiral CPL probe with high sensitivity (about 10(-2) mol·dm(-3)) and high selectivity for L-histidine at pH 3 and for L-arginine at pH 7. The mechanism of iCPL was evaluated by analysis of the fine structures in the luminescence spectra and the amino acid concentration dependence of glum. For the [Eu(pda)2](-)-histidine/arginine systems, the europium(III) complexes possess coordination structures similar to that in the crystal with slight distortion to form a chiral structure due to specific interaction with two zwitterionic amino acids. This mechanism was in stark contrast to that of the europium(III) complex-pyrrolidonecarboxylic acid system in which one amino acid coordinates to the Eu(III) ion to yield an achiral coordination structure.

  9. Palladium alpha-lipoic acid complex formulation enhances activities of Krebs cycle dehydrogenases and respiratory complexes I-IV in the heart of aged rats.

    Science.gov (United States)

    Sudheesh, N P; Ajith, T A; Janardhanan, K K; Krishnan, C V

    2009-08-01

    Age-related decline in the capacity to withstand stress, such as ischemia and reperfusion, results in congestive heart failure. Though the mechanisms underlying cardiac decay are not clear, age dependent somatic damages to mitochondrial DNA (mtDNA), loss of mitochondrial function, and a resultant increase in oxidative stress in heart muscle cells may be responsible for the increased risk for cardiovascular diseases. The effect of a safe nutritional supplement, POLY-MVA, containing the active ingredient palladium alpha-lipoic acid complex, was evaluated on the activities of the Krebs cycle enzymes such as isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, and malate dehydrogenase as well as mitochondrial complexes I, II, III, and IV in heart mitochondria of aged male albino rats of Wistar strain. Administration of 0.05 ml/kg of POLY-MVA (which is equivalent to 0.38 mg complexed alpha-lipoic acid/kg, p.o), once daily for 30 days, was significantly (pKrebs cycle dehydrogenases, and mitochondrial electron transport chain complexes. The unique electronic and redox properties of palladium alpha-lipoic acid complex appear to be a key to this physiological effectiveness. The results strongly suggest that this formulation might be effective to protect the aging associated risk of cardiovascular and neurodegenerative diseases.

  10. A novel therapeutic strategy for experimental stroke using docosahexaenoic acid complexed to human albumin

    Directory of Open Access Journals (Sweden)

    Belayev Ludmila

    2016-01-01

    Full Text Available Despite tremendous efforts in ischemic stroke research and significant improvements in patient care within the last decade, therapy is still insufficient. There is a compelling, urgent need for safe and effective neuroprotective strategies to limit brain injury, facilitate brain repair, and improve functional outcome. Recently, we reported that docosahexaenoic acid (DHA; 22:6, n-3 complexed to human albumin (DHA-Alb is highly neuroprotective after temporary middle cerebral artery occlusion (MCAo in young rats. This review highlights the potency of DHA-Alb therapy in permanent MCAo and aged rats and whether protection persists with chronic survival. We discovered that a novel therapy with DHA-Alb improved behavioral outcomes accompanied by attenuation of lesion volumes even when animals were allowed to survive three weeks after experimental stroke. This treatment might provide the basis for future therapeutics for patients suffering from ischemic stroke.

  11. Extraction of lycopene from tomato paste by ursodeoxycholic acid using the selective inclusion complex method.

    Science.gov (United States)

    Seifi, Mahmoud; Seifi, Parisa; Hadizadeh, Farzin; Mohajeri, Seyed Ahmad

    2013-11-01

    Lycopene, a precursor of β-carotene with well-known antioxidant activity and powerful health properties, can be found in many natural products such as tomato (Lycopersicon esculentum), watermelon, red pepper, and papaya. Many separation methods have been reported for extracting lycopene from its sources. The inclusion complex is an effective method for extraction and purification of organic chemicals. This procedure has 2 main components: host and guest molecules. In this study, lycopene (guest) was extracted from tomato paste by ursodeoxycholic acid, the inclusive agent (host). The molecular structure of the extracted lycopene was then confirmed by (1) HNMR and its purity was evaluated using high-performance liquid chromatography and UV-Vis spectrophotometry methods, in comparison with a standard product. The results indicated that the proposed separation method was very promising and could be used for the extraction and purification of lycopene from tomato paste.

  12. The guanidine and maleic acid (1:1) complex. The additional theoretical and experimental studies

    Science.gov (United States)

    Drozd, Marek; Dudzic, Damian

    2012-04-01

    On the basis of experimental literature data the theoretical studies for guanidinium and maleic acid complex with using DFT method are performed. In these studies the experimental X-ray data for two different forms of investigated crystal were used. During the geometry optimization process one equilibrium structure was found, only. According to this result the infrared spectrum for one theoretical molecule was calculated. On the basis of potential energy distribution (PED) analysis the clear-cut assignments of observed bands were performed. For the calculated molecule with energy minimum the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were obtained and graphically illustrated. The energy difference (GAP) between HOMO and LUMO was analyzed. Additionally, the nonlinear properties of this molecule were calculated. The α and β (first and second order) hyperpolarizability values are obtained. On the basis of these results the title crystal was classified as new second order NLO generator.

  13. Hydrogen bonded complexes of cyanuric acid with pyridine and guanidinium carbonate

    Indian Academy of Sciences (India)

    K Sivashankar

    2000-12-01

    Hydrogen bonded complexes of cyanuric acid (CA) with pyridine, [C3N3H3O3:C5H5N], 1, and guanidinium carbonate [C3H2N3][C(NH2)3], 2, have been prepared at room temperature and characterized by single-crystal X-ray diffraction. Structure of 1 shows pyridine molecules substituting the inter-tape hydrogen bond in CA by N-H…N and C-H…O hydrogen bonds. The structure reveals CA-pyridine hydrogen-bonded single helices held together by dimeric N-H…O hydrogen bonding between CA molecules. In 2, the CA tapes, resembling a sine wave interact with the guanidinium cations through N-H…O and N-H…N hydrogen bonds forming guanidinium cyanurate sheets.

  14. Preparation and Properties of Cellutose-Alginic Acid Interpolymeric Complex Films

    Institute of Scientific and Technical Information of China (English)

    Xian-Hua HE; Mei-Yu HUANG; Ying-Yan JIANG

    2005-01-01

    @@ 1Introduction General synthetic polymers such as polyethylene, polyvinyl chloride, polystyrene etc. have been produced and used in large quantities. They are very cheap, but their wastes are difficult to decompose in nature so to cause environmental pollution . In order to overcome such disadvantage, various kinds of biodegradable synthetic polymers such as polyactic acid, aliphatic polyester, polyvinyl alcohol complexes etc. have been researched[1]. However, they are expensive, so cannot be manufactured on large scale. Biopolymers such as starch and cellulose have been used as raw materials to prepare biodegradable polymer materials[1,2]. Starch derivatives and starch containing materials have been prepared to obtain relatively cheap biodegradable polymer materials, but their water proofness is not so good[2].

  15. Pharmacological Study on Antitumor Activity of 5-Fluorouracil-1-Acetic Acid and Its Rare Earth Complexes

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The antitumor activity of 5-fluorouracil-1-acetic acid(HFAA) and its lanthanide complexes(La(FAA)3, Eu(FAA)3) were studied. The results show that HFAA, La(FAA)3 and Eu(FAA)3 with the concentrations of 1.0×10-5~1.0×10-2 μg·ml-1 inhibit the colony formation of leukemia cells(L1210) and the growth of transplanted tumor sarcoma 180(S180), hepatic carcinoma(HEPA) and ehrlich ascites tumor(EC) as well. The maximum inhibitory rate of Eu(FAA)3 for S180 is 38.4%, that HFAA and La(FAA)3 for EC are 22.4% and 43.4%, respectively. The life prolongation rate of Eu(FAA)3 for HEPA bearing mice is as long as 284%.

  16. Regulation of fatty acid oxidation in mouse cumulus-oocyte complexes during maturation and modulation by PPAR agonists.

    Directory of Open Access Journals (Sweden)

    Kylie R Dunning

    Full Text Available Fatty acid oxidation is an important energy source for the oocyte; however, little is known about how this metabolic pathway is regulated in cumulus-oocyte complexes. Analysis of genes involved in fatty acid oxidation showed that many are regulated by the luteinizing hormone surge during in vivo maturation, including acyl-CoA synthetases, carnitine transporters, acyl-CoA dehydrogenases and acetyl-CoA transferase, but that many are dysregulated when cumulus-oocyte complexes are matured under in vitro maturation conditions using follicle stimulating hormone and epidermal growth factor. Fatty acid oxidation, measured as production of ³H₂O from [³H]palmitic acid, occurs in mouse cumulus-oocyte complexes in response to the luteinizing hormone surge but is significantly reduced in cumulus-oocyte complexes matured in vitro. Thus we sought to determine whether fatty acid oxidation in cumulus-oocyte complexes could be modulated during in vitro maturation by lipid metabolism regulators, namely peroxisome proliferator activated receptor (PPAR agonists bezafibrate and rosiglitazone. Bezafibrate showed no effect with increasing dose, while rosiglitazone dose dependently inhibited fatty acid oxidation in cumulus-oocyte complexes during in vitro maturation. To determine the impact of rosiglitazone on oocyte developmental competence, cumulus-oocyte complexes were treated with rosiglitazone during in vitro maturation and gene expression, oocyte mitochondrial activity and embryo development following in vitro fertilization were assessed. Rosiglitazone restored Acsl1, Cpt1b and Acaa2 levels in cumulus-oocyte complexes and increased oocyte mitochondrial membrane potential yet resulted in significantly fewer embryos reaching the morula and hatching blastocyst stages. Thus fatty acid oxidation is increased in cumulus-oocyte complexes matured in vivo and deficient during in vitro maturation, a known model of poor oocyte quality. That rosiglitazone further

  17. Effect of glutamic acid on copper sorption onto kaolinite - Batch experiments and surface complexation modeling.

    Science.gov (United States)

    Karimzadeh, Lotfollah; Barthen, Robert; Stockmann, Madlen; Gruendig, Marion; Franke, Karsten; Lippmann-Pipke, Johanna

    2017-07-01

    High carbonate content of the European Kupferschiefer ore deposits is a challenge for acid copper leaching (pH ≤ 2). Therefore investigating the mobility behavior of Cu(II) under conditions related to an alternative, neutrophil biohydrometallurgical Cu(II) leaching approach is of interest. As glutamic acid (Glu) might be present as a component in the growth media, we studied its effects on the adsorption of Cu(II) onto kaolinite. The binary and ternary batch sorption measurements of Cu(II) and Glu onto kaolinite were performed in the presence of 10 mM NaClO4 as background electrolyte and at a pH range from 4 to 9. Sorption experiments were modeled by the charge-distribution multi-site ion complexation (CD-MUSIC) model by using single sorption site (≡SOH) and monodentate surface complexation reactions. Glu sorption on kaolinite is weak (<10%) and independent of pH. Furthermore, Glu slightly enhances the Cu(II) sorption at low pH but strongly hinders (up to 50%) the sorption at higher pH and therewith enhances copper mobility. The results of isotherms show that Cu(II)-Glu sorption onto kaolinite mimics the Freundlich model. The proposed CD-MUSIC model provides a close fit to the experimental data and predicts the sorption of Cu(II), Cu(II)-Glu and Glu onto kaolinite as well as the effect of Glu on Cu(II) mobility. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Antibacterial, antibiofilm and antioxidant screening of copper(II)-complexes with some S-alkyl derivatives of thiosalicylic acid. Crystal structure of the binuclear copper(II)-complex with S-propyl derivative of thiosalicylic acid

    Science.gov (United States)

    Bukonjić, Andriana M.; Tomović, Dušan Lj.; Nikolić, Miloš V.; Mijajlović, Marina Ž.; Jevtić, Verica V.; Ratković, Zoran R.; Novaković, Slađana B.; Bogdanović, Goran A.; Radojević, Ivana D.; Maksimović, Jovana Z.; Vasić, Sava M.; Čomić, Ljiljana R.; Trifunović, Srećko R.; Radić, Gordana P.

    2017-01-01

    The spectroscopically predicted structure of the obtained copper(II)-complex with S-propyl derivative of thiosalicylic acid was confirmed by X-ray structural study. The binuclear copper(II)-complex with S-propyl derivative of thiosalicylic acid crystallized in two polymorphic forms with main structural difference in the orientation of phenyl rings relative to corresponding carboxylate groups. The antibacterial activity was tested determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) by using microdilution method. The influence on bacterial biofilm formation was determined by tissue culture plate method. In general, the copper(II)-complexes manifested a selective and moderate activity. The most sensitive bacteria to the effects of Cu(II)-complexes was a clinical isolate of Pseudomonas aeruginosa. For this bacteria MIC and biofilm inhibitory concentration (BIC) values for all tested complexes were in the range or better than the positive control, doxycycline. Also, for the established biofilm of clinical isolate Staphylococcus aureus, BIC values for the copper(II)-complex with S-ethyl derivative of thiosalicylic acid,[Cu2(S-et-thiosal)4(H2O)2] (C3) and copper(II)-complex with S-butyl derivative of thiosalicylic acid, [Cu2(S-bu-thiosal)4(H2O)2] (C5) were in range or better than the positive control. All the complexes acted better against Gram-positive bacteria (Staphylococcus aureus and Staphylococcus aureus ATCC 25923) than Gram-negative bacteria (Proteus mirabilis ATCC 12453, Pseudomonas aeruginosa, and P. aeruginosa ATCC 27855). The complexes showed weak antioxidative properties tested by two methods (1,1-diphenyl-2-picrylhydrazyl (DPPH) and reducing power assay).

  19. Crystal Structure of a Linear Ag(Ⅰ) Complex with Niflumic Acid and Its Fluorescent Property

    Institute of Scientific and Technical Information of China (English)

    TAN Yu-Hui; YANG Shao-Ping; LI Qing-Song; TAN Yu-Li

    2006-01-01

    A novel Ag(Ⅰ) complex AgH(Nifa)2 1 (C26H17AgF6N4O4, Mr = 671.31) was synthe- sized through hydrothermal reaction of Ag2SO4 and Niflumic acid (HNifa), and characterized by single-crystal X-ray determination, IR and fluorescent spectra. Crystal data for 1: monoclinic, space group C2/c, with a = 9.5446(16), b = 12.3203(16), c = 21.056 (3) (A), β = 98.075(2)o, V = 2451.5(6) (A)3, T = 293(2) K, Z = 4, Dc = 1.819 g/cm3, F(000) = 1336, μ = 0.912 mm-1, S = 1.001, (Δρ)min = -0.849, the final R = 0.0391 and wR = 0.1286. The local geometry around the central metal Ag(Ⅰ) ion is linear. Two carboxylic acids of neighboring ligands sharing one hydrogen atom by two hydro- gen bonds result in the formation of an infinite hydrogen-bonded chain. Solid-state fluorescence of 1 at room temperature shows that the maximal emission peak occurs in 439 nm.

  20. The radiolysis of CMPO: effects of acid, metal complexation and alpha vs. gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Mincher, B.J.; Groenewold, G.S. [Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415 (United States); Mezyk, S.P. [California State University at Long Beach, Long Beach, CA 90840 (United States)

    2016-07-01

    The organophosphorus amide octyl(phenyl)-N,N-diisobutyl-carbamoylmethyl phosphine oxide (CMPO) is proposed for use in fuel cycle separations as a group actinide/lanthanide extractant. Alternative compounds such as the mono-amides and diglycol amides (DGAs) proposed for actinide and/or actinide/lanthanide extraction also contain the amidic functional group, but do not contain the CMPO aromatic or phosphoryl groups. Their radiation stability is in the order mono-amides > CMPO > DGA for irradiation under similar conditions. Although they produce similar radiolysis products, the kinetics of degradation for CMPO are completely different than for the other amides. CMPO degradation occurs in a zero-order fashion, and the -G-value for the change in [CMPO] is much lower when in the presence of acid. The DGAs and mono-amides degrade with pseudo-first-order kinetics and are not protected by acidity. Possible mechanistic reasons for the differences between CMPO and the other amides are discussed, as are the effects of the diluent and metal complexation on CMPO free radical reaction rates. Finally, it is also shown that α-irradiation has much less adverse effects on CMPO degradation than β/γ irradiation, both with respect to -G-values, and radiolysis product generation. (authors)

  1. Neodymium(III) Complexes of Dialkylphosphoric and Dialkylphosphonic Acids Relevant to Liquid-Liquid Extraction Systems

    Energy Technology Data Exchange (ETDEWEB)

    Lumetta, Gregg J.; Sinkov, Sergey I.; Krause, Jeanette A.; Sweet, Lucas E.

    2016-01-27

    The complexes formed during the extraction of neodymium(III) into hydrophobic solvents containing acidic organophosphorus extractants were probed by single-crystal X-ray diffractometry, visible spectrophotometry, and Fourier-transform infrared spectroscopy. The crystal structure of the compound Nd(DMP)3 (1, DMP = dimethyl phosphate) revealed a polymeric arrangement in which each Nd(III) center is surrounded by six DMP oxygen atoms in a pseudo-octahedral environment. Adjacent Nd(III) ions are bridged by (MeO)2POO– anions, forming the polymeric network. The diffuse reflectance visible spectrum of 1 is nearly identical to that of the solid that is formed when an n-dodecane solution of di-(2-ethylhexyl)phosphoric acid (HA) is saturated with Nd(III), indicating a similar coordination environment around the Nd center in the NdA3 solid. The visible spectrum of the HA solution fully loaded with Nd(III) is very similar to that of the NdA3 material, both displaying hypersensitive bands characteristic of an pseudo-octahedral coordination environment around Nd. These spectral characteristics persisted across a wide range of organic Nd concentrations, suggesting that the pseudo-octahedral coordination environment is maintained from dilute to saturated conditions.

  2. Shell and core cross-linked poly(L-lysine)/poly(acrylic acid) complex micelles.

    Science.gov (United States)

    Hsieh, Yi-Hsuan; Hsiao, Yung-Tse; Jan, Jeng-Shiung

    2014-12-21

    We report the versatility of polyion complex (PIC) micelles for the preparation of shell and core cross-linked (SCL and CCL) micelles with their surface properties determined by the constituent polymer composition and cross-linking agent. The negatively and positively charged PIC micelles with their molecular structure and properties depending on the mixing weight percentage and polymer molecular weight were first prepared by mixing the negatively and positively charged polyions, poly(acrylic acid) (PAA) and poly(L-lysine) (PLL). The feasibility of preparing SCL micelles was demonstrated by cross-linking the shell of the negatively and positively charged micelles using cystamine and genipin, respectively. The core of the micelles can be cross-linked by silica deposition to stabilize the assemblies. The shell and/or core cross-linked micelles exhibited excellent colloid stability upon changing solution pH. The drug release from the drug-loaded SCL micelles revealed that the controllable permeability of the SCL micelles can be achieved by tuning the cross-linking degree and the SCL micelles exhibited noticeable pH-responsive behavior with accelerated release under acidic conditions. With the versatility of cross-linking strategies, it is possible to prepare a variety of SCL and CCL micelles from PIC micelles.

  3. Effect of CMC Molecular Weight on Acid-Induced Gelation of Heated WPI-CMC Soluble Complex.

    Science.gov (United States)

    Huan, Yan; Zhang, Sha; Vardhanabhuti, Bongkosh

    2016-02-01

    Acid-induced gelation properties of heated whey protein isolate (WPI) and carboxymethylcellulose (CMC) soluble complex were investigated as a function of CMC molecular weight (270, 680, and 750 kDa) and concentrations (0% to 0.125%). Heated WPI-CMC soluble complex with 6% protein was made by heating biopolymers together at pH 7.0 and 85 °C for 30 min and diluted to 5% protein before acid-induced gelation. Acid-induced gel formed from heated WPI-CMC complexes exhibited increased hardness and decreased water holding capacity with increasing CMC concentrations but gel strength decreased at higher CMC content. The highest gel strength was observed with CMC 750 k at 0.05%. Gels with low CMC concentration showed homogenous microstructure which was independent of CMC molecular weight, while increasing CMC concentration led to microphase separation with higher CMC molecular weight showing more extensive phase separation. When heated WPI-CMC complexes were prepared at 9% protein the acid gels showed improved gel hardness and water holding capacity, which was supported by the more interconnected protein network with less porosity when compared to complexes heated at 6% protein. It is concluded that protein concentration and biopolymer ratio during complex formation are the major factors affecting gel properties while the effect of CMC molecular weight was less significant. © 2016 Institute of Food Technologists®

  4. Complexation of trivalent lanthanide cations by different chelation sites of malic and tartric acid (composition, stability and probable structure

    Directory of Open Access Journals (Sweden)

    Mohammed Riri

    2016-11-01

    Full Text Available The formation of colorless gadolinium complexes (x,y,z between x gadolinium ions, y ligands and z protons of some organic acids has been studied in aqueous solution. In this work we shall present the results of investigations on the interaction of the gadolinium ion (Gd3+ with different chelation sites of malic and tartric acid formed in dilute solution for pH values between 5.50 and 7.50. The structures of these new organometallic complexes are Gd3(C4H4O52·(NO33·nH2O and Gd3(C4H4O62·(NO33·nH2O (C4H4O52-: malate ions and C4H4O62-: tartrate ions. These colorless gadolinium complexes of malate and tartrate ions have no absorption band UV–visible, the indirect photometry detection (IPD study; have identified major tri-nuclear complexes of these dicarboxylic acids, giving for these colorless complexes a (3,2,2 and (3,2,3, respectively. Composition and apparent stability constant depends on the acidity of the medium. To complement previous results and to propose probable structures for these new complexes detected in solution FT-IR and FT-Raman spectroscopy have been conducted to identify the different chelation sites for both ligands.

  5. Five-coordinated oxovanadium(IV) complexes derived from amino acids and ciprofloxacin: synthesis, spectral, antimicrobial, and DNA interaction approach.

    Science.gov (United States)

    Patel, M N; Patel, S H; Chhasatia, M R; Parmar, P A

    2008-12-15

    Five-coordinated oxovanadium(IV) complexes with ciprofloxacin and various uninegative bidentate amino acids have been prepared. The structure of complexes has been investigated using spectral, physicochemical, mass spectroscopy, and elemental analyses. The antimicrobial activities (MIC) of the complexes, ligands, metal salt, and some standard drugs have been evaluated using the doubling dilution technique against Staphylococcus aureus, Bacillus subtilis, Serratia marcescens (gram-positive), and Pseudomonas aeruginosa, and Escherichia coli (gram-negative) bacteria. The result shows the significant increase in the antibacterial activity of the ligand, metal, and ciprofloxacin on complexation. The interaction of the complexes with pBR322 DNA has been investigated using spectroscopic, gel electrophoresis, and viscometric techniques. This shows that the complexes can bind to pBR322 DNA by the intercalative mode. The superoxide dismutase-like activity of the complexes has been determined.

  6. Synthesis and characterization of poly(lactic acid-co-glycolic acid) complex microspheres as drug carriers.

    Science.gov (United States)

    Wang, Fang; Liu, Xiuxiu; Yuan, Jian; Yang, Siqian; Li, Yueqin; Gao, Qinwei

    2016-10-01

    Poly(lactic-co-glycolic) acid (PLGA) is synthesized via melt polycondensation directly from lactic acid and glycolic acid with a feed molar ratio of 75/25. Bovine serum albumin, which is used as model protein, is entrapped into the poly(lactic-co-glycolic acid) microspheres with particle size of 260.9 ± 20.0 nm by the double emulsification method. Then it is the first report of producing more carboxyl groups by poly(lactic-co-glycolic acid) surface hydrolysis. The purpose is developing poly(lactic-co-glycolic acid) microspheres surface, which is modified with chitosan by chemical reaction between carboxyl groups and amine groups. The particle size and the positive zeta potential of the poly(lactic-co-glycolic acid)/chitosan microspheres are 388.2 ± 35.6 nm and 10.4 ± 2.9 mV, respectively. The drug loading ratio and encapsulation efficacy of poly(lactic-co-glycolic acid)/chitosan microspheres are 36.3% and 57.5%, which are higher than PLGA microspheres. Furthermore, the drug burst release of poly(lactic-co-glycolic acid)/chitosan microspheres at 10 h is decreased to 21.72% while the corresponding value of the poly(lactic-co-glycolic acid) microsphere is 64.56%. These results reveal that surface hydrolysis modification of poly(lactic-co-glycolic acid) is an efficient method to improve the negative potential and chemical reaction properties of the polymer. And furthermore, this study shows that chitosan-modified poly(lactic-co-glycolic acid) microspheres is a promising system for the controlled release of pharmaceutical proteins.

  7. Synthesis,characterization and properties of some rare earth complexes with pyrazolone and 2,6-pyridinecarboxylic acid

    Directory of Open Access Journals (Sweden)

    CHEN Jing

    2014-06-01

    Full Text Available A new solid ternary complex of copper with 1-phenyl-3-methyl-4-acetyl-pyrazolone-5 and 2,6-pyridinecarboxylic acid Na[Cu(PMBP (PDA]has been synthesized and characterized by elemental analysis,FT-IR,UV-Vis,XRD,TG-DTA,and XPS.The antibacterial test indicated that the complex exhibited moderate antibacterial ability against Escherichia coli and Staphylococcus aureus.The interactions of the complex with calf thymus DNA (CT DNAwas investigated by employing florescence spectroscopic studies and ultraviolet spectrum spectrom etries.The results indicated that the complex can intercalate between DNA base pairs.

  8. Syntheses and Crystal Structures of Two Complexes with 3-(3-Pyridyl)acrylic Acid

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The reaction of 3-(3-pyridyl)acrylic acid (H(3-PYA)) with Co(NO3)2·6H2O or Complex 1 crystallizes in monoclinic, space group C2/c with a = 9.9473(12), b = 13.7227(16), c =14.7376(18) (A), β = 99.043(2)°, V = 1986.7(4) (A)3, Z = 4, Dc = 1.549 g/cm3, μ = 0.921 mm 1, F(000)= 964, R = 0.0786 and wR = 0.1443. Six types of hydrogen bonds and π-π packing interactions molecular architecture. Complex 2 crystallizes in monoclinic, space group P21/n with a =11.3630(16), b = 7.0346(10), c = 12.1365(18) (A), β = 112.545(3)°, V = 896.0(2) (A)3, Z = 2, Dc =1.997 g/cm3,μ = 0.785 mm-1, F(000) = 438, R = 0.0787 and wR = 0.1550. The discrete entity Mn(Ⅱ)(3-PYD)2(H2O)4 is extended into a 3-D supramolecular architecture by four kinds of hydrogen bonds.

  9. Acid-base and catalytic properties of the products of oxidative thermolysis of double complex compounds

    Science.gov (United States)

    Pechenyuk, S. I.; Semushina, Yu. P.; Kuz'mich, L. F.; Ivanov, Yu. V.

    2016-01-01

    Acid-base properties of the products of thermal decomposition of [M(A)6] x; [M1(L)6] y (where M is Co, Cr, Cu, Ni; M1 is Fe, Cr, Co; A is NH3, 1/2 en, 1/2 pn, CO(NH2)2; and L is CN, 1/2C2O4) binary complexes in air and their catalytic properties in the oxidation reaction of ethanol with atmospheric oxygen are studied. It is found that these thermolysis products are mixed oxides of the central atoms of complexes characterized by pH values of the zero charge point in the region of 4-9, OH-group sorption limits from 1 × 10-4 to 4.5 × 10-4 g-eq/g, OH-group surface concentrations of 10-50 nm-2 in 0.1 M NaCl solutions, and S sp from 3 to 95 m2/g. Their catalytic activity is estimated from the apparent rate constant of the conversion of ethanol in CO2. The values of constants are (1-6.5) × 10-5 s-1, depending on the gas flow rate and the S sp value.

  10. Hybrid polymeric hydrogels via peptide nucleic acid (PNA)/DNA complexation.

    Science.gov (United States)

    Chu, Te-Wei; Feng, Jiayue; Yang, Jiyuan; Kopeček, Jindřich

    2015-12-28

    This work presents a new concept in hybrid hydrogel design. Synthetic water-soluble N-(2-hydroxypropyl)methacrylamide (HPMA) polymers grafted with multiple peptide nucleic acids (PNAs) are crosslinked upon addition of the linker DNA. The self-assembly is mediated by the PNA-DNA complexation, which results in the formation of hydrophilic polymer networks. We show that the hydrogels can be produced through two different types of complexations. Type I hydrogel is formed via the PNA/DNA double-helix hybridization. Type II hydrogel utilizes a unique "P-form" oligonucleotide triple-helix that comprises two PNA sequences and one DNA. Microrheology studies confirm the respective gelation processes and disclose a higher critical gelation concentration for the type I gel when compared to the type II design. Scanning electron microscopy reveals the interconnected microporous structure of both types of hydrogels. Type I double-helix hydrogel exhibits larger pore sizes than type II triple-helix gel. The latter apparently contains denser structure and displays greater elasticity as well. The designed hybrid hydrogels have potential as novel biomaterials for pharmaceutical and biomedical applications.

  11. Influence of pH and heat treatment on β-lactolobulin-oleic acid complex

    Directory of Open Access Journals (Sweden)

    Ana-Maria SIMION (CIUCIU

    2015-12-01

    Full Text Available One of the major concerns of food technologists is to produce healthier products with specific functionalities. The potential use of β-lactoglobulin as a supplement for new functional products is encouraging due to its nutritional and functional characteristics. The aim of this work was to obtain β-lactoglobulin-oleic acid complexes at different pH values (5.0, 6.0, and 7.0 and to test their stability at different temperatures (25-85°C such as to allow identifying their potential use in a variety of food products. The complexes were characterized through different fluorescence spectroscopy based techniques: phase diagram, intrinsic and extrinsic fluorescence, along with fluorescence quenching experiments. Results showed the presence of more than two structurally distinct species with intermediates as induced by thermal treatment. The heat treatment at temperatures higher than 70°C caused an increase in both intrinsic and ANS fluorescence intensity. Acrylamide quenching showed no significant differences between the values of Stern-Volmer constants as function of temperature for pH 5.0, suggesting that no significant changes occurred in the Trp microenvironments. Quenching experiments with KI lead to decreases in Stern-Volmer constants in the temperature range 25-70°C, suggesting protein folding, whereas at higher temperatures a small increase was observed suggesting unfolding and an increased accessibility of the fluorophore to the quencher for all pH values.

  12. Kinetics and mechanism of the reaction of gold(III chloride complexes with formic acid

    Directory of Open Access Journals (Sweden)

    Pacławski K.

    2015-01-01

    Full Text Available In this work, the results of kinetic studies of the redox reaction of gold(III chloride complexes ([AuCl4]- with formic acid, are presented. Obtained data suggest the complex character of the reaction which leads to the [AuCl2]- and [AuCl3(COOH]- ions formation as intermediates. In the pH range over 2.5, the final product of the reaction is metallic gold. From the analysis of kinetic data, the rate limiting step is found to be the gold metallic phase formation. The stage of Au(III reduction is relatively fast with the second-order rate constant equal to 61.8 M-1s-1 at temperature 50ºC. The rate of the studied reaction depends on the temperature, reactants concentration and chloride ions concentration. As a result of the data analysis, the scheme of the reaction path has been suggested. Also, the values of enthalpy and entropy of activation for the reaction have been determined.

  13. Burkholderia cepacia complex isolates survive intracellularly without replication within acidic vacuoles of Acanthamoeba polyphaga.

    Science.gov (United States)

    Lamothe, Julie; Thyssen, Sandra; Valvano, Miguel A

    2004-12-01

    We have previously demonstrated that isolates of the Burkholderia cepacia complex can survive intracellularly in murine macrophages and in free-living Acanthamoeba. In this work, we show that the clinical isolates B. vietnamiensis strain CEP040 and B. cenocepacia H111 survived but did not replicate within vacuoles of A. polyphaga. B. cepacia-containing vacuoles accumulated the fluid phase marker Lysosensor Blue and displayed strong blue fluorescence, indicating that they had low pH. In contrast, the majority of intracellular bacteria within amoebae treated with the V-ATPse inhibitor bafilomycin A1 localized in vacuoles that did not fluoresce with Lysosensor Blue. Experiments using bacteria fluorescently labelled with chloromethylfluorescein diacetate demonstrated that intracellular bacteria remained viable for at least 24 h. In contrast, Escherichia coli did not survive within amoebae after 2 h post infection. Furthermore, intracellular B. vietnamiensis CEP040 retained green fluorescent protein within the bacterial cytoplasm, while this protein rapidly escaped from the cytosol of phagocytized heat-killed bacteria into the vacuolar lumen. Transmission electron microscopy analysis confirmed that intracellular Burkholderia cells were structurally intact. In addition, both Legionella pneumophila- and B. vietnamiensis-containing vacuoles did not accumulate cationized ferritin, a compound that localizes within the lysosome. Thus, our observations support the notion that B. cepacia complex isolates can use amoebae as a reservoir in the environment by surviving without intracellular replication within an acidic vacuole that is distinct from the lysosomal compartment.

  14. A Cancer Stem Cell Potent Cobalt(III–Cyclam Complex Bearing Two Tolfenamic Acid Moieties

    Directory of Open Access Journals (Sweden)

    Paul B. Cressey

    2017-02-01

    Full Text Available Cancer stem cells (CSCs are thought to be responsible for cancer relapse. CSCs are a subtype of cancer cells with the ability to differentiate, self-renew, and form secondary or tertiary tumors. Current cancer treatments—including chemotherapy, radiation, and surgery—effectively remove bulk cancer cells but are unable to eliminate CSCs. Here, we present the synthesis, characterization, and anti-CSC properties of a cobalt(III–cyclam complex bearing two tolfenamic acid moieties, 3. Notably, 3 displays sub-micromolar potency towards breast CSCs and bulk breast cancer cells. Detailed mechanistic studies show that 3 is taken up readily by breast CSCs, enters the nucleus, causes DNA damage, and induces caspase-dependent apoptosis. Furthermore, 3 inhibits cyclooxygenase-2 (COX-2 expression in CSCs. The mechanism of action of 3 is similar to that of a naproxen-appended cobalt(III–cyclam complex, 1 recently reported by our group. The advantage of 3 over 1 is that it has the potential to remove whole tumor populations (bulk cancer cells and CSCs with a single dose.

  15. Complexation of mercury(II) ions with humic acids in tundra soils

    Science.gov (United States)

    Vasilevich, R. S.; Beznosikov, V. A.; Lodygin, E. D.; Kondratenok, B. M.

    2014-03-01

    The interaction mechanisms of mercury(II) ions with preparations of humic acids (HAs) isolated from organic horizons of surface-gleyed soils (Haplic Stagnosol (Gelic, Siltic)) of shrub tundra and hydromorphic peat gley soils (Histic Cryosol (Reductaquic, Siltic)) of moss-lichen tundra have been studied. The particular features of the interactions between the mercury(II) ions and the HAs are related to the molecular structure of the HAs, the mercury concentration range, and the environmental parameters. The fixation of mercury(II) ions into stable coordination compounds is most efficient in the pH range of 2.5-3.5. At the element concentrations below 0.50 μmol/dm3, the main complexing sites of HAs are their peripheral aminoacid functional groups. Pyrocatechol, salicylate, and phenolic groups from the nuclear moiety of molecules interact in the concentration range of 0.0005-0.50 mmol/dm3; the physical sorption of mercury hydroxo complexes by the surface of HAs is the main process occurring in the system.

  16. Metal-organic complex-functionalized protein nanopore sensor for aromatic amino acids chiral recognition.

    Science.gov (United States)

    Guo, Yanli; Niu, Aihua; Jian, Feifei; Wang, Ying; Yao, Fujun; Wei, Yongfeng; Tian, Lei; Kang, Xiaofeng

    2017-03-27

    Chiral recognition at single-molecule level for small active molecules is important, as exhibited by many nanostructures and molecular assemblies in biological systems, but it presents a significant challenge. We report a simple and rapid sensing strategy to discriminate all enantiomers of natural aromatic amino acids (AAA) using a metal-organic complex-functionalized protein nanopore, in which a chiral recognition element and a chiral recognition valve were equipped. A trifunctional molecule, heptakis-(6-deoxy-6-amino)-β-cyclodextrin (am7βCD), was non-covalently lodged within the nanopore of an α-hemolysin (αHL) mutant, (M113R)7-αHL. Copper(ii) ion reversibly bonds to the amino group of am7βCD to form an am7βCD-Cu(II) complex, which allowed chiral recognition for each enantiomer in the mixture of AAA by distinct current signals. The Cu(II) plugging valve plays a crucial rule that holds chiral molecules in the nanocavity for a sufficient registering time. Importantly, six enantiomers of all nature AAA could be simultaneously recognized at one time. Enantiomeric excess (ee) could also be accurately detected by this approach. It should be possible to generalize this approach for sensing of other chiral molecules.

  17. Electrocatalytic Oxidation of Formate with Nickel Diphosphane Dipeptide Complexes. Effect of Ligands Modified with Amino Acids

    Energy Technology Data Exchange (ETDEWEB)

    Galan, Brandon R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Reback, Matthew L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jain, Avijita [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Appel, Aaron M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shaw, Wendy J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-09-03

    A series of nickel bis-diphosphine complexes with dipeptides appended to the ligands were investigated for the catalytic oxidation of formate. Typical rates of ~7 s-1 were found, similar to the parent complex (~8 s-1), with amino acid size and positioning contributing very little to rate or operating potential. Hydroxyl functionalities did result in lower rates, which were recovered by protecting the hydroxyl group. The results suggest that the overall dielectric introduced by the dipeptides does not play an important role in catalysis, but free hydroxyl groups do influence activity suggesting contributions from intra- or intermolecular interactions. These observations are important in developing a fundamental understanding of the affect that an enzyme-like outer coordination sphere can have upon molecular catalysts. This work was funded by the US DOE Basic Energy Sciences, Chemical Sciences, Geoscience and Biosciences Division (BRG, AJ, AMA, WJS), the US DOE Basic Energy Sciences, Physical Bioscience program (MLR). Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

  18. Electrochemiluminescence properties of Tb(III) nicotinic acid complex and its analytical application

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yu [College of Chemistry and Material Science, Anhui Normal University, No. 1 Beijing East Road, Wuhu 241000 (China); Zhang, Yuqin [The Department of Material Engineering, Wuhu Institute of Technology, No. 201 Wenjin Road, Wuhu 241003 (China); Shu, Guibo; Dong, Qin; Zou, Lili [College of Chemistry and Material Science, Anhui Normal University, No. 1 Beijing East Road, Wuhu 241000 (China); Zhu, Yinggui, E-mail: ygzhu08@mail.ahnu.edu.cn [College of Chemistry and Material Science, Anhui Normal University, No. 1 Beijing East Road, Wuhu 241000 (China)

    2015-03-15

    A water soluble lanthanide Tb(III) complex Tb{sub 2}(C{sub 6}NO{sub 2}H{sub 4}){sub 6}(H{sub 2}O){sub 4} has been synthesized as luminescent material, and it is characterized by X-ray crystallography, infrared spectra and elemental analysis, respectively. This material showed excellent characterize of electrochemiluminescence (ECL) in the presence of co-reactant potassium peroxodisulfate (K{sub 2}S{sub 2}O{sub 8}) at glassy carbon electrode. With the increase of the concentration for nicotinic acid (NA), the ECL intensity of the complex/K{sub 2}S{sub 2}O{sub 8} system in HAc–NaAc buffer solution will be decreased apparently. Novel approach for the detection of nicotinic acid (NA) was developed based on the quenching effect of NA. Furthermore, the possible mechanisms for the ECL behavior of Tb{sub 2}(C{sub 6}NO{sub 2}H{sub 4}){sub 6}(H{sub 2}O){sub 4}/K{sub 2}S{sub 2}O{sub 8} system are proposed. The effects of K{sub 2}S{sub 2}O{sub 8} concentration, pH of the buffer on the ECL intensity have also been discussed in detail. The experiment results showed that the limit of detection for NA was 6.0×10{sup −7} M (S/N=3) with a linear range of 2.0×10{sup −6}–2.0×10{sup −4} M. - Highlights: • A novel ECL material Tb{sub 2}(H{sub 2}O){sub 4}(C{sub 6}NO{sub 2}H{sub 4}){sub 6} was synthesized and characterized. • The ECL property of the terbium chelate has been studied detail, and possible mechanism was been proposed. • A new ECL method for the determination of nicotinic acid with a wide liner range and a low detection limit was proposed.

  19. Stereoselective Alkane Oxidation with meta-Chloroperoxybenzoic Acid (MCPBA) Catalyzed by Organometallic Cobalt Complexes.

    Science.gov (United States)

    Shul'pin, Georgiy B; Loginov, Dmitriy A; Shul'pina, Lidia S; Ikonnikov, Nikolay S; Idrisov, Vladislav O; Vinogradov, Mikhail M; Osipov, Sergey N; Nelyubina, Yulia V; Tyubaeva, Polina M

    2016-11-22

    Cobalt pi-complexes, previously described in the literature and specially synthesized and characterized in this work, were used as catalysts in homogeneous oxidation of organic compounds with peroxides. These complexes contain pi-butadienyl and pi-cyclopentadienyl ligands: [(tetramethylcyclobutadiene)(benzene)cobalt] hexafluorophosphate, [(C₄Me₄)Co(C₆H₆)]PF₆ (1); diiodo(carbonyl)(pentamethylcyclopentadienyl)cobalt, Cp*Co(CO)I₂ (2); diiodo(carbonyl)(cyclopentadienyl)cobalt, CpCo(CO)I₂ (3); (tetramethylcyclobutadiene)(dicarbonyl)(iodo)cobalt, (C₄Me₄)Co(CO)₂I (4); [(tetramethylcyclobutadiene)(acetonitrile)(2,2'-bipyridyl)cobalt] hexafluorophosphate, [(C₄Me₄)Co(bipy)(MeCN)]PF₆ (5); bis[dicarbonyl(B-cyclohexylborole)]cobalt, [(C₄H₄BCy)Co(CO)₂]₂ (6); [(pentamethylcyclopentadienyl)(iodo)(1,10-phenanthroline)cobalt] hexafluorophosphate, [Cp*Co(phen)I]PF₆ (7); diiodo(cyclopentadienyl)cobalt, [CpCoI₂]₂ (8); [(cyclopentadienyl)(iodo)(2,2'-bipyridyl)cobalt] hexafluorophosphate, [CpCo(bipy)I]PF₆ (9); and [(pentamethylcyclopentadienyl)(iodo)(2,2'-bipyridyl)cobalt] hexafluorophosphate, [Cp*Co(bipy)I]PF₆ (10). Complexes 1 and 2 catalyze very efficient and stereoselective oxygenation of tertiary C-H bonds in isomeric dimethylcyclohexanes with MCBA: cyclohexanols are produced in 39 and 53% yields and with the trans/cis ratio (of isomers with mutual trans- or cis-configuration of two methyl groups) 0.05 and 0.06, respectively. Addition of nitric acid as co-catalyst dramatically enhances both the yield of oxygenates and stereoselectivity parameter. In contrast to compounds 1 and 2, complexes 9 and 10 turned out to be very poor catalysts (the yields of oxygenates in the reaction with cis-1,2-dimethylcyclohexane were only 5%-7% and trans/cis ratio 0.8 indicated that the oxidation is not stereoselective). The chromatograms of the reaction mixture obtained before and after reduction with PPh₃ are very similar, which testifies that alkyl

  20. Cytotoxicity of copper(II)-complexes with some S-alkyl derivatives of thiosalicylic acid. Crystal structure of the binuclear copper(II)-complex with S-ethyl derivative of thiosalicylic acid

    Science.gov (United States)

    Nikolić, Miloš V.; Mijajlović, Marina Ž.; Jevtić, Verica V.; Ratković, Zoran R.; Novaković, Slađana B.; Bogdanović, Goran A.; Milovanović, Jelena; Arsenijević, Aleksandar; Stojanović, Bojana; Trifunović, Srećko R.; Radić, Gordana P.

    2016-07-01

    The spectroscopically predicted structure of the obtained copper(II)-complex with S-ethyl derivative of thiosalicylic acid was confirmed by X-ray structural study and compared to previously reported crystal structure of the Cu complex with S-methyl derivative. Single crystals suitable for X-ray measurements were obtained by slow crystallization from a water solution. Cytotoxic effects of S-alkyl (R = benzyl (L1), methyl (L2), ethyl (L3), propyl (L4) and butyl (L5)) derivatives of thiosalicylic acid and the corresponding binuclear copper(II)-complexes on murine colon carcinoma cell lines, CT26 and CT26.CL25 and human colon carcinoma cell line HCT-116 were reported here. The analysis of cancer cell viability showed that all the tested complexes had low cytotoxic effect on murine colon carcinoma cell lines, but several times higher cytotoxicity on normal human colon carcinoma cells.

  1. Bovine lactoferrin binds oleic acid to form an anti-tumor complex similar to HAMLET.

    Science.gov (United States)

    Fang, Bing; Zhang, Ming; Tian, Mai; Jiang, Lu; Guo, Hui Yuan; Ren, Fa Zheng

    2014-04-04

    α-Lactalbumin (α-LA) can bind oleic acid (OA) to form HAMLET-like complexes, which exhibited highly selective anti-tumor activity in vitro and in vivo. Considering the structural similarity to α-LA, we conjectured that lactoferrin (LF) could also bind OA to obtain a complex with anti-tumor activity. In this study, LF-OA was prepared and its activity and structural changes were compared with α-LA-OA. The anti-tumor activity was evaluated by methylene blue assay, while the apoptosis mechanism was analyzed using flow cytometry and Western blot. Structural changes of LF-OA were measured by fluorescence spectroscopy and circular dichroism. The interactions of OA with LF and α-LA were evaluated by isothermal titration calorimetry (ITC). LF-OA was obtained by heat-treatment at pH8.0 with LD50 of 4.88, 4.95 and 4.62μM for HepG2, HT29, and MCF-7 cells, respectively, all of which were 10 times higher than those of α-LA-OA. Similar to HAMLET, LF-OA induced apoptosis in tumor cells through both death receptor- and mitochondrial-mediated pathways. Exposure of tryptophan residues and the hydrophobic regions as well as the loss of tertiary structure were observed in LF-OA. Besides these similarities, LF showed different secondary structure changes when compared with α-LA, with a decrease of α-helix and β-turn and an increase of β-sheet and random coil. ITC results showed that there was a higher binding number of OA to LF than to α-LA, while both of the proteins interacted with OA through van der Waals forces and hydrogen bonds. This study provides a theoretical basis for further exploration of protein-OA complexes. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

  2. SYNTESIS OF THE COMPLEXES OF MACROPOROUS SULFONATED RESINS WITH FERRIC CHLORIDE AND THEIR CATALYTIC BEHAVIOR FOR SETERIFICATION OF ACETIC ACID WITH BUTANOL

    Institute of Scientific and Technical Information of China (English)

    HuangWenqiang; HouXin; 等

    1997-01-01

    The complex resins prepared from macroporous sulfonated resin D72(H+ form) with ferric chloride or ferric chloride hexahydrate have both sites of Bronsted acid and Lewis acid.In the catalysis of exterification of acetic acid with butanol the complex resins show to have much higher catalytic activity than that of its matrix.a conventional sulfonated cation exchange resin D72.

  3. Use of Chromophoric Ligands to Visually Screen Co-crystals of Putative Protein-Nucleic Acid Complexes

    Science.gov (United States)

    Jiang, Xiaohua; Egli, Martin

    2011-01-01

    Distinguishing between crystals of protein-nucleic acid complexes and those containing protein alone is a common problem in structural studies of protein-nucleic acid interactions. Currently there are several methods available for detecting nucleic acid in crystals, including gel electrophoresis, SYBR Gold fluorescence dye staining and methyl violet staining. However, they require either that the crystals be sacrificed or access to a fluorescence microscope. In this protocol, we describe an approach that allows direct visualization of either the presence or absence of oligonucleotides in crystals grown from solutions containing both protein and nucleic acid – labeling with the Cy5 dye. In addition to offering the advantage of being able to distinguish between crystals of complex and protein alone with the naked eye or a light microscope, crystals of covalently Cy5-labeled DNA can be directly used for X-ray diffraction data collection. PMID:21901673

  4. Synthesis of 3,5-diisopropyl(carboxy- sup 14 C)salicylic acid and its sup 67 Cu complex

    Energy Technology Data Exchange (ETDEWEB)

    Chidambaram, M.V.; Epperson, C.E.; Williams, S.; Gray, R.A.; Sorenson, J.R.J. (Univ. of Arkansas for Medical Sciences, Little Rock (USA). College of Pharmacy)

    1991-03-01

    The synthesis of 3,5-diisopropyl(carboxy-{sup 14}C)salicylic acid was achieved via Kolbe-Schmitt carboxylation of potassium 2,4-di-isopropylphenolate. The yield of this acid was 81% based upon the weight of the product and 93% based upon radioactivity incorporated into the labeled acid which contains 98% {sup 14}C in the carboxyl group (specific activity = 5.1 {mu}Ci/mg). The labeled acid was characterized by ultraviolet spectrophotometry and purity established by thin-layer chromatography, autoradiography, and liquid scintillation counting. A 90% yield of the double labeled {sup 14}C, {sup 67}Cu-complex (specific activity = 4.6 {mu}Ci {sup 67}Cu/mg) was obtained using conditions developed with non-radioactive reactants. The presence of {sup 67}Cu in this complex was established using {gamma}-ray emission spectrophometry. (author).

  5. Synthesis, physicochemical studies, embryos toxicity and DNA interaction of some new Iron(II) Schiff base amino acid complexes

    Science.gov (United States)

    Abdel-Rahman, Laila H.; El-Khatib, Rafat M.; Nassr, Lobna A. E.; Abu-Dief, Ahmed M.

    2013-05-01

    New Fe(II) Schiff base amino acid complexes derived from the condensation of o-hydroxynaphthaldehyde with L-alanine, L-phenylalanine, L-aspartic acid, L-histidine and L-arginine were synthesized and characterized by elemental analysis, IR, electronic spectra, and conductance measurements. The stoichiometry and the stability constants of the complexes were determined spectrophotometrically. The investigated Schiff bases exhibited tridentate coordination mode with the general formulae [Fe(HL)2]·nH2O for all amino acids except L-histidine. But in case of L-histidine, the ligand acts as tetradentate ([FeL(H2O)2]·2H2O), where HL = mono anion and L = dianion of the ligand. The structure of the prepared complexes is suggested to be octahedral. The prepared complexes were tested for their toxicity on chick embryos and found to be safe until a concentration of 100 μg/egg with full embryos formation. The interaction between CT-DNA and the investigated complexes were followed by spectrophotometry and viscosity measurements. It was found that, the prepared complexes bind to DNA via classical intercalative mode and showed a different DNA cleavage activity with the sequence: nhi > nari > nali > nasi > nphali. The thermodynamic Profile of the binding of nphali complex and CT-DNA was constructed by analyzing the experimental data of absorption titration and UV melting studies with the McGhee equation, van't Hoff's equation, and the Gibbs-Helmholtz equation.

  6. Preparation of polymer-rare earth complex using salicylic acid-containing polystyrene and its fluorescence emission property

    Energy Technology Data Exchange (ETDEWEB)

    Gao Baojiao, E-mail: gaobaojiao@126.com [Department of Chemical Engineering, North University of China, Taiyuan 030051 (China); Zhang Wei; Zhang Zhengguo; Lei Qingjuan [Department of Chemical Engineering, North University of China, Taiyuan 030051 (China)

    2012-08-15

    Salicylic acid (SA) was first bonded onto the side chains of polystyrene (PS), obtaining functional macromolecule SAPS. Using the salicylic acid-containing polystyrene as a macromolecular ligand, a polymer-rare earth complex, SAPS-Eu(III), was prepared. The structure of SAPS-Eu(III) was characterized, and the fluorescence properties of SAPS-Eu(III) were mainly investigated. The experimental results show that the complex SAPS-Eu(III) has fine chemical stability because of the bidentate chelating effect of salicylic acid ligand. More important, the ligand SA on the side chains of PS can strongly sensitize the fluorescence emission of the center ion, Eu{sup 3+} ion, and it enables the complex SAPS-Eu(III) to produce the apparent 'Antenna Effect'. In the diluted solution of the functional macromolecule SAPS, the formed complex SAPS-Eu(III) belongs to an intramolecular complex, or an intrachain complex. For the binary intramolecular complex SAPS-Eu(III), the apparent saturated coordination number of SA of SAPS towards Eu{sup 3+} ion is equal to 10, and here the binary intrachain complex SAPS-Eu(III) has the strongest fluorescence emission. On this basis, small-molecule 1,10-phenanthroline (Phen) acting as a co-ligand is added and the ternary complex SAPS-Eu(III)-Phen will be formed. As long as a small amount of Phen is added (in the molar ratio 1:1 (n(Phen):n(Eu))), the coordination of the two kinds of ligands, SA of SAPS and Phen, to Eu{sup 3+} ion will reach complete saturation, and here the fluorescence emission of the ternary complex will be further enhanced via the complementary coordination effect in comparison with that of the binary complex SAPS-Eu(III). - Highlights: Black-Right-Pointing-Pointer We prepared the functional polystyrene, SAPS, on whose side chain salicylic acid ligand was bonded. Black-Right-Pointing-Pointer The polymer-rare earth complex, SAPS-Eu(III), was prepared and a stronger 'antenna effect' was produced. Black

  7. Investigation of non-covalent complexes of glutathione with common amino acids by electrospray ionization mass spectrometry

    Institute of Scientific and Technical Information of China (English)

    Zhao-yun DAI; Yan-qiu CHU; Bo WU; Liang WU; Chuan-fan DING

    2008-01-01

    Aim: To study the non-covalent interaction between glutathione and common amino acids. Methods: A stoichiometry of glutathione and common amino acids were mixed to reach the equilibrium, and then the mixed solution was investigated by electrospray ionization mass spectrometry (ESI-MS). The binding of the com-plexes was further examined by collision-induced dissociation (CID) in a tandem mass spectrometer as well as UV spectroscopy. To avoid distinct ionization effi-ciency discrepancy and signal suppression in the ESI-MS measurements, the interaction between glutathione (GSH) and glutamate (Glu) was quantitatively evaluated. The total concentrations and series of m/z of peak intensities for glu-tathione and amino acids could be achieved, respectively. Due to the existence of some oligomeric species arising from glutathione or amino acids, an improved calculation formula was proposed to calculate the dissociation constants of glu-tathione binding to amino acids. Results: The ESI mass spectra revealed that glutathione could interact easily with Met, Phe, Tyr, Ser, or lie to form non-cova-lent complexes. The binding of the complexes was further confirmed by CID experiments in a tandem mass spectrometer as well as UV spectroscopy. Moreover, an improved calculation formula was successfully applied to determine the disso-ciation constants of glutathione binding to Glu, His, or Gln. Finally, a possible formation mechanism for the complexes of glutathione with amino acids was proposed. Conclusion: The reduced polypeptide y-glutathione can interact with each of 8 common amino acids, including Glu, His, and Gin to form non-covalent complexes with different affinity.

  8. Enantioselective Direct Mannich-Type Reactions Catalyzed by Frustrated Lewis Acid/Brønsted Base Complexes.

    Science.gov (United States)

    Shang, Ming; Cao, Min; Wang, Qifan; Wasa, Masayuki

    2017-09-05

    An enantioselective direct Mannich-type reaction catalyzed by a sterically frustrated Lewis acid/Brønsted base complex is disclosed. Cooperative functioning of the chiral Lewis acid and achiral Brønsted base components gives rise to in situ enolate generation from monocarbonyl compounds. Subsequent reaction with hydrogen-bond-activated aldimines delivers β-aminocarbonyl compounds with high enantiomeric purity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Lanthanide(III and Yttrium(III Complexes of Benzimidazole-2-Acetic Acid: Synthesis, Characterisation and Effect of La(III Complex on Germination of Wheat

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available The synthesis and characterisation of lanthanide(III and yttrium(III nitrate complexes of benzimidazole-2-acetic acid (HBIA are reported. The complexes have been characterised by elemental analysis, molar conductance, magnetic studies, IR, 1 H NMR, UV-visible, EPR, and TG/DTA studies. They have the stoichiometry [ Ln 3 ( BIA 2 ( NO 3 7 ( H 2 O 4 ]⋅3 H 2 O where Ln=La(III, Pr(III, Nd(II, Sm(III, Eu(III, Gd(III, Tb(III, Dy(III, and Y(III. The effect of La(III complex on germination, coleoptile, and root length of two local varieties of wheat DWR-195 and GW-349 for different treatment periods has been investigated. The complex was found to exhibit enhanced activity, compared to HBIA or metal salt alone at lower treatment periods.

  10. Humic Acid Complexation of Th, Hf and Zr in Ligand Competition Experiments: Metal Loading and Ph Effects

    Science.gov (United States)

    Stern, Jennifer C.; Foustoukos, Dionysis I.; Sonke, Jeroen E.; Salters, Vincent J. M.

    2014-01-01

    The mobility of metals in soils and subsurface aquifers is strongly affected by sorption and complexation with dissolved organic matter, oxyhydroxides, clay minerals, and inorganic ligands. Humic substances (HS) are organic macromolecules with functional groups that have a strong affinity for binding metals, such as actinides. Thorium, often studied as an analog for tetravalent actinides, has also been shown to strongly associate with dissolved and colloidal HS in natural waters. The effects of HS on the mobilization dynamics of actinides are of particular interest in risk assessment of nuclear waste repositories. Here, we present conditional equilibrium binding constants (Kc, MHA) of thorium, hafnium, and zirconium-humic acid complexes from ligand competition experiments using capillary electrophoresis coupled with ICP-MS (CE- ICP-MS). Equilibrium dialysis ligand exchange (EDLE) experiments using size exclusion via a 1000 Damembrane were also performed to validate the CE-ICP-MS analysis. Experiments were performed at pH 3.5-7 with solutions containing one tetravalent metal (Th, Hf, or Zr), Elliot soil humic acid (EHA) or Pahokee peat humic acid (PHA), and EDTA. CE-ICP-MS and EDLE experiments yielded nearly identical binding constants for the metal- humic acid complexes, indicating that both methods are appropriate for examining metal speciation at conditions lower than neutral pH. We find that tetravalent metals form strong complexes with humic acids, with Kc, MHA several orders of magnitude above REE-humic complexes. Experiments were conducted at a range of dissolved HA concentrations to examine the effect of [HA]/[Th] molar ratio on Kc, MHA. At low metal loading conditions (i.e. elevated [HA]/[Th] ratios) the ThHA binding constant reached values that were not affected by the relative abundance of humic acid and thorium. The importance of [HA]/[Th] molar ratios on constraining the equilibrium of MHA complexation is apparent when our estimated Kc, MHA values

  11. KINETIC STUDY OF CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE OVER A NOVEL COPOLYMER- BOUND CIS- DICARBONYLRHODIUM COMPLEX

    Institute of Scientific and Technical Information of China (English)

    CHEN Yuying; YUAN Guoqing; CHEN Rongyao

    1989-01-01

    The kinetic study of carbonylation of methanol-acetic acid mixture to acetic acid and acetic anhydride over a cis-dicarbonylrhodium complex (MVM' Rh)coordinated with the ethylene diacrylate (M')crosslinked copolymer of methyl acrylate (M) and 2 - vinylpyridine (V) shows that the rate of reaction is zero order with respect to both reactants methanol and carbon monoxide, but first order in the concentrations of promoter methyl iodide and rhodium in the complex . Polar solvents can accelerate the reaction .Activation parameters were calculated from the experimental results, being comparable to that of the homogeneous system . A mechanism similar to that of soluble rhodium catalyst was proposed .

  12. Synthesis and characterization of mixed ligand complexes of bio-metals with pyrimidine nucleoside (uridine) and amino acids

    Indian Academy of Sciences (India)

    P Rabindra Reddy; A Mohan Reddy

    2000-12-01

    The mixed ligand complexes of Cu(II), Ni(II) and Co(II) with uridine and amino acids, L-alanine, L-phenylalanine and L-tryptophan were synthesized and characterized by elemental analysis, conductivity data, infrared spectra, electronic spectra and magnetic susceptibility data. In these complexes, the nucleoside (uridine) acts as a monodentate ligand coordinating through O(4) under the conditions of investigation, whereas the amino acids coordinate through the carboxylate oxygen and the amino nitrogen. Distorted octahedral geometry for Cu(II) and octahedral geometries for both Ni(II) and Co(II) are proposed.

  13. Humic Acid Complexation of Th, Hf and Zr in Ligand Competition Experiments: Metal Loading and Ph Effects

    Science.gov (United States)

    Stern, Jennifer C.; Foustoukos, Dionysis I.; Sonke, Jeroen E.; Salters, Vincent J. M.

    2014-01-01

    The mobility of metals in soils and subsurface aquifers is strongly affected by sorption and complexation with dissolved organic matter, oxyhydroxides, clay minerals, and inorganic ligands. Humic substances (HS) are organic macromolecules with functional groups that have a strong affinity for binding metals, such as actinides. Thorium, often studied as an analog for tetravalent actinides, has also been shown to strongly associate with dissolved and colloidal HS in natural waters. The effects of HS on the mobilization dynamics of actinides are of particular interest in risk assessment of nuclear waste repositories. Here, we present conditional equilibrium binding constants (Kc, MHA) of thorium, hafnium, and zirconium-humic acid complexes from ligand competition experiments using capillary electrophoresis coupled with ICP-MS (CE- ICP-MS). Equilibrium dialysis ligand exchange (EDLE) experiments using size exclusion via a 1000 Damembrane were also performed to validate the CE-ICP-MS analysis. Experiments were performed at pH 3.5-7 with solutions containing one tetravalent metal (Th, Hf, or Zr), Elliot soil humic acid (EHA) or Pahokee peat humic acid (PHA), and EDTA. CE-ICP-MS and EDLE experiments yielded nearly identical binding constants for the metal- humic acid complexes, indicating that both methods are appropriate for examining metal speciation at conditions lower than neutral pH. We find that tetravalent metals form strong complexes with humic acids, with Kc, MHA several orders of magnitude above REE-humic complexes. Experiments were conducted at a range of dissolved HA concentrations to examine the effect of [HA]/[Th] molar ratio on Kc, MHA. At low metal loading conditions (i.e. elevated [HA]/[Th] ratios) the ThHA binding constant reached values that were not affected by the relative abundance of humic acid and thorium. The importance of [HA]/[Th] molar ratios on constraining the equilibrium of MHA complexation is apparent when our estimated Kc, MHA values

  14. Syntheses and fluorescent properties of complexes of Eu(Ⅲ) with HTTA,TPPO and benzoic acid

    Institute of Scientific and Technical Information of China (English)

    ZHAN Xuehui; XIAO Zhongliang; ZHAN Hanhui; ZHAO Xuehui; ZHOU Suian; LI Fei

    2009-01-01

    A series of Eu(Ⅲ) complexes of α-thenoyltrifluoroacetone(HTTA) with trioctylphosphine oxide(TPPO) and benzoic acid(BA) or its two derivatives, p-toluic acid(PTA) and p-methoxybenzoic acid(POA) were synthesized and were characterized with elemental analysis, IR spectroscopy, scanning electronic microscopy and fluorescent spectra. The complexes were revealed to be Eu(BA)(TTA)2TPPO2, Eu(PTA)(TTA)2TPPO2 and Eu(POA)(TTA)2TPPO2. The excitation and absorption spectra of the complex Eu(POA)(TTA)2TPPO2 in MeOH solution were investigated in detail. The experimental result showed that relatively cheap materials with sharp red luminescence could be pre-pared, when benzoic acid or its two derivatives were added in Eu(Ⅲ) complexes of α-thenoyltdfluoroacetone with trioctylphosphine oxide. The relative fluorescence intensity of the Eu(Ⅲ) complexes decreased in the following order: Eu(POA)(TTA)2TPPO2> Eu(PTA)(TTA)2TPPO2>Eu(BA)(TTA)2TPPO2.

  15. Synthesis, Characterization and Fluorescence Properties of Europium, Terbium Complexes with Biphenyl-4-Carboxylic Acid and o-Phenanthroline

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Two series of solid complexes of europium and terbium with biphenyl 4-carboxylic acid and phen were synthesized and characterized in this report. Their elemental analysis, molar conductivities and TG-DTA studies indicate that the complexes have the composition of Eu(phen)L3·1/2H2O, Eu0.5RE0.5(phen)L3·1/2H2O; Tb(phen)L3·H2O and Tb0.5RE0.5(Phen)L3·1/2H2O. (RE=Y3+, La3+ and Gd3+; L=biphenyl 4-carboxylic acid; phen=o-Phenanthroline). The studies of their IR, UV 1H NMR and molar conductivities demonstrate that biphenyl 4-carboylic acid is bounded with RE(Ⅲ) ion. Rare earth ions coordinate with two nitrogen atoms of phen molecules directly in these rare earth complexes. The fluorescence spectra and fluorescence lifetimes of the rare earth complexes show that the fluorescent intensity and lifetime of a series of europium complexes are longer than those of the series of terbium complexes as having the some ligands. There are better fluorescent intensity and lifetime of hetero-nuclear rare earth complexes than homo-nuclear rare earth complexes for europium complexes. The fluorescence emission intensity of Eu3+ is raised by inert fluorescent rare earth ions (Y3+, Gd3+ and La3+), but in Tb3+ hetero-nuclear rare earth complexes the intensity of Tb3+ ions are quenched by the inert fluorescent rare earth ions.

  16. Interpolymer complexes of poly(acrylic acid) and chitosan: influence of the ionic hydrogel-forming medium.

    Science.gov (United States)

    de la Torre, Paloma M; Torrado, Susana; Torrado, Santiago

    2003-04-01

    Non-covalent polyionic complexes were developed for localized antibiotic delivery in the stomach. Freeze-dried interpolymer complexes based on polyacrylic acid (PAA) and chitosan (CS) were prepared in a wide range of copolymer compositions by dissolving both polymers in acidic conditions. The influence of hydrogel-forming medium on the swelling and drug release was evaluated. The properties of these complexes were investigated by using scanning electron microscopy, dynamic swelling/eroding and release experiments in enzyme-free simulated gastric fluid (SGF). The electrostatic polymer/polymer interactions generate polyionic complexes with different porous structures. In a low pH environment, the separation of both polymer chains augmented as the amount of cationic and carboxilic groups increased within the network. However, the presence of higher amount of ions in the hydrogel-forming medium produced a network collapse, decreasing the maximum swelling ratio in SGF. PAA:CS:A (1:2.5:2)-1.75 M complexes released around 54% and 71% of the amoxicillin in 1 and 2 h, respectively, in acidic conditions. A faster drug release from this interpolymer complex was observed when the ionic strength of the hydrogel-forming medium increased. Complexes with a high amount of both polymer chains within the network, PAA:CS:A(2.5:5:2), showed a suitable amoxicillin release without being affected by an increased amount of ions in the hydrogel-forming medium. These freeze-dried interpolymer complexes could serve as potential candidates for amoxicillin delivery in an acidic enviroment.

  17. Hydration of the simplest α-keto acid: a rotational spectroscopic and ab initio study of the pyruvic acid-water complex.

    Science.gov (United States)

    Schnitzler, Elijah G; Seifert, Nathan A; Ghosh, Supriya; Thomas, Javix; Xu, Yunjie; Jäger, Wolfgang

    2017-02-08

    Intermolecular interactions between pyruvic acid, the simplest α-keto acid, and water are important in bio- and atmospheric chemistry. In this context, the pure rotational spectrum of the pyruvic acid-water complex was measured from 7 to 15 GHz using a cavity-based Fourier-transform microwave spectrometer. In the detected isomer, water acts as a hydrogen bond donor and acceptor, bridging the acidic hydrogen and the keto oxygen. Both a- and b-type transitions were observed; however, c-type transitions were not observed, due to vibrational averaging of the effectively barrier-less wagging motion of the free hydrogen of the water subunit, which results in an effective ground state structure with a plane of symmetry. The mass distribution out of the ab-plane, corrected for the out-of-plane hydrogen atoms of the methyl group, confirms that the complex has a plane of symmetry. The observed transitions exhibit splittings due to internal rotations of the water subunit and the methyl group. The proposed internal rotation of water nominally breaks one hydrogen bond, so it is remarkable that the barrier was calculated to be as low as 5.2 kJ mol(-1); however, a non-covalent interactions analysis indicates that water rotation has surprisingly little effect on the interactions between the water and pyruvic acid subunits. The barrier to methyl internal rotation was determined to be about 4.6 kJ mol(-1) experimentally, significantly higher than that of the pyruvic acid monomer. In general, the structure and dynamics investigated here provide insights into the interactions between pyruvic acid and water that dictate the fate of pyruvic acid in aqueous aerosols and living cells.

  18. Classification of pseudo pairs between nucleotide bases and amino acids by analysis of nucleotide–protein complexes

    OpenAIRE

    Kondo, Jiro; Westhof, Eric

    2011-01-01

    Nucleotide bases are recognized by amino acid residues in a variety of DNA/RNA binding and nucleotide binding proteins. In this study, a total of 446 crystal structures of nucleotide–protein complexes are analyzed manually and pseudo pairs together with single and bifurcated hydrogen bonds observed between bases and amino acids are classified and annotated. Only 5 of the 20 usual amino acid residues, Asn, Gln, Asp, Glu and Arg, are able to orient in a coplanar fashion in order to form pseudo ...

  19. DABO Boronates: Stable Heterocyclic Boronic Acid Complexes for Use in Suzuki-Miyaura Cross-Coupling Reactions.

    Science.gov (United States)

    Reilly, Maureen K; Rychnovsky, Scott D

    2011-10-01

    Diethanolamine complexed heterocyclic boronic acids (DABO boronates) are air-stable reagents that can be used directly in Suzuki-Miyaura reactions in the presence of water or a protic co-solvent. Interestingly, heterocyclic DABO boronates can be stored for extended periods of time at room temperature with no noticeable degradation, unlike their boronic acid counterparts. Heterocyclic DABO boronates constitute an operationally simple and efficient alternative to other boronic acid derivatives as coupling partners in palladium catalyzed cross-coupling reactions under standard Suzuki-Miyaura conditions.

  20. Syntheses and applications of Eu(Ⅲ)complexes of 2-thienyltrifluoroacetonate, terephthalic acid and phenanthroline as light conversion agents

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xue-hui; HUANG Ke-long; JIAO Fei-peng; YANG You-ping; LI Zhao-jian; LIU Zhi-guo; HU Shun-qin

    2007-01-01

    A series of europium(Ⅲ)complexes of 2-thienyltrifluoroacetonate(HTTA), terephthalic acid(TPA) and phenanthroline (Phen) were synthesized.The new complexes Eu(TPA)(TTA)Phen and Eu2(TPA)(TTA)4Phen2 were characterized by elemental analysis, IR spectrum, scanning electron microscope and thermal stability analysis.The results show that the thermal stability of the Eu(Ⅲ)complexes increases in the following order: the mononuclear complex Eu(TTA)3Phen, the binuclear complex Eu2(TPA)(TTA)4Phen2, the chain polynuclear complex Eu(TPA)(TTA)Phen. And the formation of the binuclear/polynuclear structure of the new complexes appears to be responsible for the enhancement of their thermal and optical stability.In addition, The fluorescence excitation spectra of these new complexes show more broad excitation bands than that of the complex Eu(TTA)3Phen corresponding to their formation.The enhancement of Eu3+ fluorescence in the new complexes Can be observed by the addition of Gd3+.The bright red luminescent plastics carl be obtained when the complex EuGd(TPA)(TTA)4Phen2 is added above 0.5%(mass fraction).

  1. Thermodynamics of mixed-ligand complex formation of zinc nitrilotriacetate with amino acids and dipeptides in solution

    Energy Technology Data Exchange (ETDEWEB)

    Pyreu, Dmitrii, E-mail: pyreu@mail.ru [Department of Inorganic and Analytic Chemistry, Ivanovo State UniversityErmak 39, Ivanovo 153025 (Russian Federation); Gruzdev, Matvey; Kumeev, Roman [G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Ivanovo (Russian Federation); Gridchin, Sergei [Ivanovo State University of Chemistry and Technology, Ivanovo (Russian Federation)

    2014-10-20

    Highlights: • Stable mixed ligand complexes of ZnNta with amino acids and dipeptides. • Histamine-like coordination mode of His in the complex ZnNtaHis. • Glycine-like coordination of Lys and Orn in the complexes ZnNtaL and ZnNtaHL • NH{sub 2}, CO-coordination mode of GlyGly in the complex ZnNtaGG. • NH{sub 2}, N{sup −} or NH2, N{sup −}, COO-coordination modes of GlyGly in the complex ZnNtaGGH{sub −1}. - Abstract: The isothermal calorimetry, pH-potentiometric titration and {sup 1}H and {sup 13}C NMR methods has been used to study the mixed-ligand complex formation in the systems Zn{sup 2+}–Nta{sup 3–}–L{sup −} (L = His, Orn, Lys, GlyGly, AlaAla) in aqueous solution at 298.15 K and the ionic strength of I = 0.5 (KNO{sub 3}). The thermodynamic parameters of formation of the mixed complexes have been determined. The relationship between the probable coordination modes of the complexone and amino acid or dipeptide molecules in the mixed-ligand complex and the thermodynamic parameters has been discussed.

  2. In situ synthesis of twelve dialkyltartrate-boric acid complexes and two polyols-boric acid complexes and their applications as chiral ion-pair selectors in nonaqueous capillary electrophoresis.

    Science.gov (United States)

    Wang, Li-Juan; Yang, Juan; Yang, Geng-Liang; Chen, Xing-Guo

    2012-07-27

    In this paper, twelve dialkyltartrate-boric acid complexes and two polyols-boric acid complexes were in situ synthesized by the reaction of different dialkyltartrates or polyols with boric acid in methanol containing triethylamine. All of the twelve dialkyltartrate-boric acid complexes were found to have relatively good chiral separation performance in nonaqueous capillary electrophoresis (NACE). Their chiral recognition effects in terms of both enantioselectivity (α) and resolution (R(s)) were similar when the number of carbon atoms was below six in the alkyl group of alcohol moiety. The dialkyltartrates containing alkyl groups of different structures but the same number of carbon atoms, i.e. one of straight chain and one of branched chain, also provided similar chiral recognition effects. Furthermore, it was demonstrated for the first time that two methanol insoluble polyols, D-mannitol and D-sorbitol, could react with boric acid to prepare chiral ion-pair selectors using methanol as the solvent medium. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Synthesis and fluorescence properties of Tb(Ⅲ) complexes with pyridine-2,6-dicarboxylic acid derivatives

    Institute of Scientific and Technical Information of China (English)

    TANG Rui-ren; ZHENG You-hu; GU Guo-liang

    2008-01-01

    Two novel ligands named 4-styrylpyridine-2,6-dicarboxylic acid (4-SPDA) and 4-(4-(2-(2, 6-dicarboxypyridin-4-yl)-vinyl)styryl)pyridine-2,6-dicarboxylic acid(DSPDA) and their complexes with Tb(Ⅲ) were synthesized and characterized by infrared spectrometry, 1H nuclear magnetic resonance, elemental analysis and gas chromatograph-mass spectrometry. The ligand synthetic route was optimized. The fluorescence properties of the complex in solid state, in different kind of solvents and in solutions with different pH values were investigated in detail. The results show that the yields of DSPDA and 4-SPDA reach over 78% by Wittig-Horner reaction and other eight pyridine-2, 6-dicarboxylic acid derivatives with different substituents on pyridine ring, and their complexes with Tb(Ⅲ) are also obtained. The fluorescence intensities of the complexes with electron-donating groups are more intense than those of the complexes with electron-withdrawing groups on pyridine ring; fluorescence intensities of the complexes are the strongest in neutral solution (pH=7), and the less the dipole moment of solvent molecule is, the stronger the fluorescence intensity is. It is found that the two ligands (4-APDA and DSPDA) are the good sensitizers for Tb(Ⅲ) ion.

  4. Acidity and complex formation studies of 3-(adenine-9-yl)-propionic and 3-(thymine-1-yl)-propionic acids in ethanol-water media

    Science.gov (United States)

    Hammud, Hassan H.; El Shazly, Shawky; Sonji, Ghassan; Sonji, Nada; Bouhadir, Kamal H.

    2015-05-01

    The ligands 3-(adenine-9-yl)propionic acid (AA) and 3-(thymine-1-yl)propionic acid (TA) were prepared by N9-alkylation of adenine and N1-alkylation of thymine with ethylacrylate in presence of a base catalyst, followed by acid hydrolysis of the formed ethyl esters to give the corresponding propionic acid derivatives. The products were characterized by spectral methods (FTIR, 1H NMR and 13C NMR), which confirm their structures. The dissociation constants of ligands, were potentiometrically determined in 0.3 M KCl at 20-50 °C temperature range. The work was extended to study complexation behavior of AA and TA with various biologically important divalent metal ions (Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Mn2+ and Pb2+) in 50% v/v water-ethanol medium at four different temperatures, keeping ionic strength constant (0.3 M KCl). The order of the stability constants of the formed complexes decreases in the sequence Cu2+ > Pb2+ > Zn2+ > Ni2+ > Co2+ > Mn2+ > Cd2+ for both ligands. The effect of temperature was also studied and the corresponding thermodynamic functions (ΔG, ΔH, ΔS) were derived and discussed. The formation of metal complexes has been found to be spontaneous, and the stability constants were dependant markedly on the basicity of the ligands.

  5. Complexity

    CERN Document Server

    Gershenson, Carlos

    2011-01-01

    The term complexity derives etymologically from the Latin plexus, which means interwoven. Intuitively, this implies that something complex is composed by elements that are difficult to separate. This difficulty arises from the relevant interactions that take place between components. This lack of separability is at odds with the classical scientific method - which has been used since the times of Galileo, Newton, Descartes, and Laplace - and has also influenced philosophy and engineering. In recent decades, the scientific study of complexity and complex systems has proposed a paradigm shift in science and philosophy, proposing novel methods that take into account relevant interactions.

  6. Redox potentials of dopamine and its supramolecular complex with aspartic acid

    Science.gov (United States)

    Liu, Tao; Han, Ling-Li; Du, Chun-Mei; Yu, Zhang-Yu

    2014-07-01

    Dopamine (DA) can be oxidized to dopamine quinone (DAquinone) through a one-step, two-electron redox reaction. The electron transfer property of DA and its supramolecular complex with aspartic acid (Asp) has been investigated by the theoretical calculations. We calculated the standard redox potentials ( E o) of DA/DAquinone at the MP2/6-31G( d,p)//B3LYP/6-31G( d,p), MP2/6-31+G( d,p)//B3LYP/6-31+G( d,p), MP2/6-31G( d,p)//B3LYP/6-311G( d,p), and MP2/6-311+G( d,p)//B3LYP/6-311+G( d,p) levels. Comparing the experimental value, the redox potentials of DA/DAquinone obtained at MP2//B3LYP/6-311G( d,p) and MP2//B3LYP/6-311+G( d,p) levels can be considered as the upper and lower estimates. DA can form supramolecular complex (DA-Asp) with Asp through hydrogen bond (H-bond). Therefore, the values of 0.631 and 0.628 V obtained at MP2//B3LYP/6-311G( d,p) and MP2//B3LYP/6-311+G( d,p) levels for DA-Asp/DAquinone-Asp can be proposed as the upper and lower estimates of a probable (about 0.630 V) value of the corresponding redox potential. The calculated E o values of DA-Asp/DAquinone-Asp at the four theoretical levels are upper than those of DA/DAquinone, which indicates that the formation of H-bonds weaken the electron-donating ability of DA.

  7. Nitrogen-doped carbon nanofoam derived from amino acid chelate complex for supercapacitor applications

    Science.gov (United States)

    Ramakrishnan, Prakash; Shanmugam, Sangaraju

    2016-06-01

    We report a novel strategy to fabricate the nitrogen-doped mesoporous carbon nanofoam structures (N-MCNF), derived from magnesium amino acid chelate complex (Mg-acc-complex) for its application towards high performance supercapacitor (SCs) system. A series of N-MCNF with well-connected carbon nanofoam structure have been developed by varying the synthesis temperature. The fabricated N-MCNF material possesses a high surface area (1564 m2 g-1) and pore volume (1.767 cm3 g-1) with nitrogen content of 3.42 wt%. A prototypical coin cell type symmetric N-MCNF SC device has been assembled with 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIMBF4] ionic liquid electrolyte, and evaluated for SCs studies. The N-MCNF with high textural properties delivers unprecedented SC performance, such as high specific capacitance (204 Fg-1 at 0.25 Ag-1, 25 °C), high energy density (63.4 Wh kg-1), high power density (35.9 kW kg-1) and long-term cycle life (32,500 cycles). Significantly, N-MCNF materials exhibited high power rate performance, at 500 mV-1 (115 Fg-1) and 25 Ag-1 (166 Fg-1) owing to the uniform mesopore size distribution (∼4 nm). The N-MCNF SC device delivered maximum energy densities of 83.4 and 93.3 Wh kg-1 at 60 °C and 90 °C, respectively. Such outstanding N-MCNF SC device is successfully demonstrated in solar energy harvester applications.

  8. Supramolecular complex formation of β-cyclodextrin polymer with substituted salicylic acid or 3-hydroxy-2-naphthoic acid and their electrorheological behaviors

    Institute of Scientific and Technical Information of China (English)

    GAO Ziwei; ZHAO Xiaopeng; SUN Ping; SI Gang

    2004-01-01

    According to the chemical design, electrorheological properties of supramolecular complex from β-cyclodextrin polymer (β -CDP) were discussed. Six supramolecular complexes of β-cyclodextrin polymer with substituted salicylic acid and 3-hydroxy-2-naphthoic acid were synthesized by the solid-phase self-assembly method, and their component and structure were characterized by NMR, FT-IR, UV-vis and the fluorescence analysis. Then the electrorheological properties of their suspensions in silicone oil were investigated under DC electric fields. It was found that the yield stresses of these supramolecular complex ER fluids were 7.3-9.8 kPa at 4kV/mm in DC electric field, which were enhanced by 34%-72% compared with that of pure β-CDP. Among them, that of β-CDP/3-hydroxy-2-naphthoic acid ER fluid was the highest. It was also found that the ER effect of supramolecular complexes can be controlled by changing different guests. When the substituted group is at phenyl ring, ER behavior can be slightly adjusted by the different substituted groups, their number as well as their position at phenyl ring. This can be proved by the measurement of dielectric properties.

  9. Coordination behavior of N-benzoylamino acids: Synthesis and structure of mixed-ligand complexes of palladium(Ⅱ) with N-benzoylamino acid dianion and diamine

    Institute of Scientific and Technical Information of China (English)

    龚钰秋; 陈耀峰; 顾建明; 胡秀荣

    1997-01-01

    Four new mixed-ligand complexes of pailadiumt(Ⅱ) with L1(N-benzoyl-α-amino acid dianion) and L2[ethyldiamine (en),2,2’-bipyridine (Bpy) and 1,10-phenanthroline (Phen)] were synthesized.Ail the complexes have been characterized by elemental analyses,molar conductance,infrared and 1H NMR spectra and therme-gravimetric analyses.Crystal structures of [Pd(Bpy)(Bzval-N,O)] and [Pd(en) (Bzphe-N,O)] H2O have been do termmed by X-ray diffraction analysis.The results indicate that in all the complexes hgand L1 coordinates to palladium (Ⅱ) through deprotonated amide nitrogen and carboxylic oxygen,and there are some intramolecular nonrovalent in teractions in the complexes.

  10. Exploring DNA binding and nucleolytic activity of few 4-aminoantipyrine based amino acid Schiff base complexes: A comparative approach

    Science.gov (United States)

    Raman, N.; Sakthivel, A.; Pravin, N.

    A series of novel Co(II), Cu(II), Ni(II) and Zn(II) complexes were synthesized from Schiff base(s), obtained by the condensation of 4-aminoantipyrine with furfural and amino acid (glycine(L1)/alanine(L2)/valine(L3)) and respective metal(II) chloride. Their structural features and other properties were explored from the analytical and spectral methods. The binding behaviors of the complexes to calf thymus DNA were investigated by absorption spectra, viscosity measurements and cyclic voltammetry. The intrinsic binding constants for the above synthesized complexes are found to be in the order of 102 to 105 indicating that most of the synthesized complexes are good intercalators. The binding constant values (Kb) clearly indicate that valine Schiff-base complexes have more intercalating ability than alanine and glycine Schiff-base complexes. The results indicate that the complexes bind to DNA through intercalation and act as efficient cleaving agents. The in vitro antibacterial and antifungal assay indicates that these complexes are good antimicrobial agents against various pathogens. The IC50 values of [Ni(L1)2] and [Zn(L1)2] complexes imply that these complexes have preferable ability to scavenge hydroxyl radical.

  11. Exploring DNA binding and nucleolytic activity of few 4-aminoantipyrine based amino acid Schiff base complexes: a comparative approach.

    Science.gov (United States)

    Raman, N; Sakthivel, A; Pravin, N

    2014-05-05

    A series of novel Co(II), Cu(II), Ni(II) and Zn(II) complexes were synthesized from Schiff base(s), obtained by the condensation of 4-aminoantipyrine with furfural and amino acid (glycine(L1)/alanine(L2)/valine(L3)) and respective metal(II) chloride. Their structural features and other properties were explored from the analytical and spectral methods. The binding behaviors of the complexes to calf thymus DNA were investigated by absorption spectra, viscosity measurements and cyclic voltammetry. The intrinsic binding constants for the above synthesized complexes are found to be in the order of 10(2) to 10(5) indicating that most of the synthesized complexes are good intercalators. The binding constant values (Kb) clearly indicate that valine Schiff-base complexes have more intercalating ability than alanine and glycine Schiff-base complexes. The results indicate that the complexes bind to DNA through intercalation and act as efficient cleaving agents. The in vitro antibacterial and antifungal assay indicates that these complexes are good antimicrobial agents against various pathogens. The IC50 values of [Ni(L1)2] and [Zn(L1)2] complexes imply that these complexes have preferable ability to scavenge hydroxyl radical.

  12. Microencapsulation of stearidonic acid soybean oil in Maillard reaction-modified complex coacervates.

    Science.gov (United States)

    Ifeduba, Ebenezer A; Akoh, Casimir C

    2016-05-15

    The antioxidant capacity of Maillard reaction (MR)-modified gelatin (GE)-gum arabic (GA) coacervates was optimized to produce microcapsules with superior oxidative stability compared to the unmodified control. MR was used to crosslink GE and GA, with or without maltodextrin (MD), to produce anti-oxidative Maillard reaction products (MRP) which was used to encapsulate stearidonic acid soybean oil (SDASO) by complex coacervation. Biopolymer blends (GE-GA [1:1, w/w] or GE-GA-MD [2:2:1, w/w/w]) were crosslinked by dry-heating at 80°C for 4, 8, or 16h. Relationships between the extent of browning, Trolox equivalent antioxidant capacity (TEAC), and the total oxidation (TOTOX) of encapsulated SDASO were fitted to quadratic models. The [GE-GA-MD] blends exhibited higher browning rates and TEAC values than corresponding [GE-GA] blends. Depending on the type of biopolymer blend and dry-heating time, TOTOX values of SDASO in MRP-derived microcapsules were 29-87% lower than that of the non-crosslinked control after 30 days of storage.

  13. Standing of nucleic acid testing strategies in veterinary diagnosis laboratories to uncover Mycobacterium tuberculosis complex members

    Directory of Open Access Journals (Sweden)

    Pedro eCosta

    2014-10-01

    Full Text Available Nucleic acid testing (NAT designate any molecular approach used for the detection, identification and characterization of pathogenic microorganisms, enabling the rapid, specific and sensitive diagnostic of infectious diseases, such as tuberculosis. These assays have been widely used since the 90´s of the last century in human clinical laboratories and, subsequently, also in veterinary diagnostics. Most NAT strategies are based in the polymerase chain reaction (PCR and its several enhancements and variations. From the conventional PCR, real-time PCR and its combinations, isothermal DNA amplification, to the nanotechnologies, here we review how the NAT assays have been applied to decipher if and which member of the Mycobacterium tuberculosis complex is present in a clinical sample. Recent advances in DNA sequencing also brought new challenges and have made possible to generate rapidly and at a low cost, large amounts of sequence data. This revolution with the high-throughput sequencing (HTS technologies makes whole genome sequencing (WGS and metagenomics the trendiest NAT strategies, today. The ranking of NAT techniques in the field of clinical diagnostics is rising, and we provide a SWOT (Strengths, Weaknesses, Opportunities and Threats analysis with our view of the use of molecular diagnosis for detecting tuberculosis in veterinary laboratories, notwithstanding the gold standard being still the classical culture of the agent. The complementary use of both classical and molecular diagnosis approaches is recommended to speed the diagnostic, enabling a fast decision by competent authorities and rapid tackling of the disease.

  14. Standing of nucleic acid testing strategies in veterinary diagnosis laboratories to uncover Mycobacterium tuberculosis complex members.

    Science.gov (United States)

    Costa, Pedro; Botelho, Ana; Couto, Isabel; Viveiros, Miguel; Inácio, João

    2014-01-01

    Nucleic acid testing (NAT) designate any molecular approach used for the detection, identification, and characterization of pathogenic microorganisms, enabling the rapid, specific, and sensitive diagnostic of infectious diseases, such as tuberculosis. These assays have been widely used since the 90s of the last century in human clinical laboratories and, subsequently, also in veterinary diagnostics. Most NAT strategies are based in the polymerase chain reaction (PCR) and its several enhancements and variations. From the conventional PCR, real-time PCR and its combinations, isothermal DNA amplification, to the nanotechnologies, here we review how the NAT assays have been applied to decipher if and which member of the Mycobacterium tuberculosis complex is present in a clinical sample. Recent advances in DNA sequencing also brought new challenges and have made possible to generate rapidly and at a low cost, large amounts of sequence data. This revolution with the high-throughput sequencing (HTS) technologies makes whole genome sequencing (WGS) and metagenomics the trendiest NAT strategies, today. The ranking of NAT techniques in the field of clinical diagnostics is rising, and we provide a SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis with our view of the use of molecular diagnostics for detecting tuberculosis in veterinary laboratories, notwithstanding the gold standard being still the classical culture of the agent. The complementary use of both classical and molecular diagnostics approaches is recommended to speed the diagnostic, enabling a fast decision by competent authorities and rapid tackling of the disease.

  15. Response surface optimization of bioremediation of Acid black 52 (Cr complex dye) using Aspergillus tamarii.

    Science.gov (United States)

    Ghosh, Arpita; Dastidar, Manisha Ghosh; Sreekrishnan, T R

    2017-02-01

    Bioremediation of the Cr complex dye (Acid black 52) was performed in batch and continuous modes using growing Aspergillus tamarii. The removal of Cu which may be present as an impurity was 100% at 100 mg/L initial dye concentration. The removal of color and Cr decreased from 87% to 4% and from 92% to 8%, respectively, by increasing dye concentration from 100 to 5000 mg/L in batch mode. The removal of color and Cr increased from 27% to 67.8% and from 32% to 72%, respectively, with increasing hydraulic retention time from 28 to 220 h at 100 mg/L dye concentration in continuous mode. For optimization of color removal using response surface methodology (RSM) the ranges of parameters were kept at dye concentration: 200-500 mg/L; pH: 4-6 and time: 35-50 hours. Maximum color removal suggested by the model was 85.6809% at initial dye concentration 200 mg/L, pH 5.25 and time 50 h. The validation experiments in batch and continuous modes were conducted at the optimum conditions as suggested by the RSM model. The theoretical and experimental responses of color removal were in close agreement in batch mode. The scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy and gas chromatography-mass spectroscopy analyses indicated biosorption and biodegradation of dye.

  16. Formation of redispersible polyelectrolyte complex nanoparticles from gallic acid-chitosan conjugate and gum arabic.

    Science.gov (United States)

    Hu, Qiaobin; Wang, Taoran; Zhou, Mingyong; Xue, Jingyi; Luo, Yangchao

    2016-11-01

    Polyelectrolyte complex (PEC) nanoparticles between chitosan (CS) and biomacromolecules offer better physicochemical properties as delivery vehicles for nutrients than other CS-based nanoparticles. Our major objective was to fabricate PEC nanoparticles between water soluble gallic acid-chitosan conjugate (GA-CS) and gum arabic. The optimal fabrication method, physicochemical characteristics and stability were investigated. Furthermore, we also evaluated the effects of nano spray drying technology on the morphology and redispersibility of nanoparticle powders using Buchi B-90 Nano Spray Dryer. Results showed that the mass ratio between GA-CS and gum arabic and the preparation pH had significant contributions in determining the particle size and count rate of the nanoparticles, with the ratio of 3:1 and pH 5.0 being the optimal conditions that resulted in 112.2nm and 122.9kcps. The polyethylene glycol (PEG) played a vital role in forming the well-separated spray dried nanoparticles. The most homogeneous nanoparticles with the smoothest surface were obtained when the mass ratio of GA-CS and PEG was 1:0.5. In addition, the GA-CS/gum arabic spray dried nanoparticles exhibited excellent water-redispersibiliy compared to native CS/gum arabic nanoparticles. Our results demonstrated GA-CS/gum arabic nanoparticles were successfully fabricated with promising physicochemical properties and great potential for their applications in food and pharmaceutical industries. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. POLYMER/MONTMORILLONITE COMPLEXES:PREPARATION AND INTERACTIONS WITH ROSIN ACID

    Institute of Scientific and Technical Information of China (English)

    Lihong Zhao; Wenxia Liu

    2004-01-01

    Polymer/montmorillonite complexes were prepared via intercalating polymers of low molecular weight into layers of montmorillonite and evaluated for their interactions with rosin acid. Three polymers from various amines modified by epichlorohydrin and an acidified diethylenetriamine were separately intercalated into montmorillonite via direct solution intercalation. X-ray diffraction patterns are performed to obtain information about the intercalation of these agents. The examination revealed that it was feasible for the direct intercalation of polymers, while hard for the unmodified diethylenetriamine. Adsorption isotherm curves were established to assess the efficiency of the various montmorillonites including the intercalated montmorillonites, the simple mixtures of the corresponding intercalation agents and ordinary montmorillonite in removing pitch from water solution. From the adsorption behavior of various samples, it was found that the interaction of the montmorillonite with pitch was not only through van der Waals attraction, but also through electrostatic interactions. Both the organo-philic and the surface electrostatic properties of the montmorillonites are important for successful pitch control.

  18. On 2:1 melamine - Squaric acid dihydrate complex: The structure and vibrational spectra

    Science.gov (United States)

    Nowicka-Scheibe, J.; Pawlukojć, A.; Sobczyk, L.; Jański, J.

    2017-01-01

    In the present paper we would like to describe the structural and dynamical properties of crystalline dihydrated complex of melamine (2,4,6-triamino-1,3,5-triazin-1-ium) with squaric acid (3,4-dihydroxycyclobut-3-ene-1,2-dione) abbreviated as MH·SQ. The X-ray diffraction studies show the presence of deprotonated units (C4O4)2- and single protonated melamine cations surrounded by tetrameric water assemblies (H2O)4. The formation of the water tetramers deserves a special attention. IR absorption and Raman spectra reflect a richness of structural units and numerous hydrogen bonds. The presence of the continua in the IR spectra, with a characteristic presence of the Hadži's trio enriched by a numerous submaxima, may be ascribed to the structural units and to the various types of hydrogen bonds. The density functional theory calculation with the periodic boundary conditions was use to precise analysis of experimental data.

  19. Stability of HAMLET--a kinetically trapped alpha-lactalbumin oleic acid complex.

    Science.gov (United States)

    Fast, Jonas; Mossberg, Ann-Kristin; Svanborg, Catharina; Linse, Sara

    2005-02-01

    The stability toward thermal and urea denaturation was measured for HAMLET (human alpha-lactalbumin made lethal to tumor cells) and alpha-lactalbumin, using circular dichroism and fluorescence spectroscopy as well as differential scanning calorimetry. Under all conditions examined, HAMLET appears to have the same or lower stability than alpha-lactalbumin. The largest difference is seen for thermal denaturation of the calcium free (apo) forms, where the temperature at the transition midpoint is 15 degrees C lower for apo HAMLET than for apo alpha-lactalbumin. The difference becomes progressively smaller as the calcium concentration increases. Denaturation of HAMLET was found to be irreversible. Samples of HAMLET that have been renatured after denaturation have lost the specific biological activity toward tumor cells. Three lines of evidence indicate that HAMLET is a kinetic trap: (1) It has lower stability than alpha-lactalbumin, although it is a complex of alpha-lactalbumin and oleic acid; (2) its denaturation is irreversible and HAMLET is lost after denaturation; (3) formation of HAMLET requires a specific conversion protocol.

  20. Polyoxometalate coordinated transition metal complexes as catalysts: Oxidation of styrene to benzaldehyde/benzoic acid

    Indian Academy of Sciences (India)

    Srinivasa Rao Amanchi; Anjali Patel; Samar K Das

    2014-11-01

    Oxidation of styrene is carried out by using heptamolybdate coordinated transition metal (Co2+, Zn2+) complexes, [2-ampH]4[{Co(H2O)5}Mo7O24]·9H2O (1), [3-ampH]4[{Co(H2O)5}Mo7O24]·9H2O (2), [2-ampH]4[{Zn(H2O)5}Mo7O24]·4H2O (3) and [3-ampH]4[{Zn(3-ampy)(H2O)4}Mo7O24]·4H2O (4) as catalysts and H2O2 as an oxidant at 80°C. The leaching study has been carried out to check the quality of catalyst and it has been reused for three times with good percentage of conversion. For the first two catalysts (compounds 1 and 2), the major product obtained is benzaldehyde, and benzoic acid is the major product for next two catalysts (compounds 3 and 4). Stability of the catalysts has been analyzed by IR, UV-spectroscopy and powder X-ray crystallography.

  1. Radioprotection by alpha-lipoic acid palladium complex formulation (POLY-MVA) in mice.

    Science.gov (United States)

    Ramachandran, Lakshmy; Krishnan, Chirakkal V; Nair, Cherupally Krishnan Krishnan

    2010-08-01

    The dietary supplement, POLY-MVA, containing palladium alpha-lipoic acid complex was examined for its efficacy as a radioprotector in mice exposed to whole-body gamma-radiation. Oral administration of POLY-MVA enhanced endogenous spleen colony formation in animals exposed to a sublethal dose of 6 Gy gamma-radiation. Alkaline comet assay revealed that the nuclear DNA comet parameters such as percent DNA in tail, tail length, tail moment, and olive tail moment, of the bone marrow cells and spleen cells, were found increased following whole-body gamma-irradiation. The radiation-induced DNA damage in these cells was reduced when POLY-MVA was administered to animals exposed to a lethal dose of 8 Gy whole-body gamma-radiation. The administration of POLY-MVA significantly reduced the gamma-radiation-induced mortality and also aided recovery from the radiation-induced loss of body weight in mice surviving after 8 Gy gamma-radiation exposure. These results suggest the potential use of POLY-MVA as a radioprotector in cases of planned radiation exposures.

  2. Bioinspired tannic acid-copper complexes as selective coating for nanofiltration membranes

    KAUST Repository

    Chakrabarty, Tina

    2017-04-27

    Bio-polyphenols that are present in tea, date fruits, chockolate and many other plants have been recognized as scaffold material for the manufacture of composite filtration membranes. These phenolic biomolecules possess abundant gallol (1,2,3-trihydroxyphenyl) and catechol (1,2-dihydroxyphenyl) functional groups, which allow the spontaneous formation of a thin polymerized layer at the right pH conditions. Here, we report a facile and cost-effective method to coat porous membranes via the complexation of tannic acid (TA) and cupric acetate (mono hydrate) through co-deposition. The modified membranes were investigated by XPS, ATR/FTIR, water contact angle, SEM and water permeance for a structural and morphological analysis. The obtained results reveal that the modified membranes with TA and cupric acetate (CuII) developed a thin skin layer, which showed excellent hydrophilicity with good water permeance. These membranes were tested with different molecular weight polyethylene glycols (PEG) in aqueous solution; the MWCO was around 600 Daltons.

  3. Quinolinic acid selectively induces apoptosis of human astrocytes: potential role in AIDS dementia complex

    Directory of Open Access Journals (Sweden)

    Wang Lily

    2005-07-01

    Full Text Available Abstract There is evidence that the kynurenine pathway (KP and particularly one of its end products, quinolinic acid (QUIN play a role in the pathogenesis of several major neuroinflammatory diseases, and more particularly AIDS dementia complex (ADC. We hypothesized that QUIN may be involved in astrocyte apoptosis because: 1 apoptotic astrocytes have been observed in the brains of ADC patients, 2 ADC patients have elevated cerebrospinal fluid QUIN concentrations, and 3 QUIN can induce astrocyte death. Primary cultures of human fetal astrocytes were treated with three pathophysiological concentrations of QUIN. Numeration of apoptotic cells was assessed using double immunocytochemistry for expression of active caspase 3 and for nucleus condensation. We found that treatment of human astrocytes with QUIN induced morphological (cell body shrinking and biochemical changes (nucleus condensation and over-expression of active caspase 3 of apoptosis. After 24 hours of treatment with QUIN 500 nM and 1200 nM respectively 10 and 14% of astrocytes were undergoing apoptosis. This would be expected to lead to a relative lack of trophic support factors with consequent neuronal dysfunction and possibly death. Astroglial apoptosis induced by QUIN provides another potential mechanism for the neurotoxicity of QUIN during ADC.

  4. Spectroscopic, thermal and structural studies of new L-leucine and D-leucine complexes with chloranilic acid

    Science.gov (United States)

    Pawlukojć, A.; Hetmańczyk, J.; Nowicka-Scheibe, J.; Maurin, Jan K.; Schilf, W.; Rozwadowski, Z.

    2017-04-01

    New molecular complexes of L-leucine and D-leucine with chloranilic acid have been synthesized. Crystal structures of these crystals have been solved; they crystallize in non-centrosymmetric monoclinic P21 space group. In the crystal, leucine molecules exist in protonated form (C6NO2H14+) and chloranilic acid molecules in deprotonated form (C6HCl2O4-). Electronic (UV-Vis) and vibrational absorption (VA) spectra for both materials were collected. Circular dichroism methods such as electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) were used to determine the absolute configuration of new complexes. In both methods a characteristic (-,+) Cotton patterns are observed. In ECD spectra absorption bands are observed at 212 nm for acetonitrile solution and at 202 nm for aqueous solution. VCD spectra (in DMSO-d6 solution) show (-,+) Cotton pattern with strong peaks at 1323 cm-1 (CH rocking mode). Differential scanning calorimetry (DSC) and thermogravimetric (TG) investigations were performed to explore thermal properties of new materials. In DSC curve the decomposition and combustion processes are observed in 220-227 °C. The decomposition process was described by use of TG method and quadruple mass spectrometer (QMS). NMR spectra of pure L-leucine and chloranilic acid as well as L-leucine - chloranilic acid complex in solutions (D2O and DMSO) and in solid state confirm the geometry of molecules in complex both in solution and in solid state.

  5. Equilibrium study on the reactions of boric acid with some cis-diaqua CrIII-complexes

    Indian Academy of Sciences (India)

    G N Mukherjee; Ansuman Das

    2003-08-01

    Substitution inert cis-diaqua CrIII complexes: cis-[(L-)CrIII(H2O)2](3-)+ derived from N-donor ligands (L-) viz., bipyridine and 1,10-phenanthroline ( = 0) and N,O-donor ligands viz., nitrilotriacetate and anthranilate N,N-diacetate ( = 3) titrate as diprotic acids in aqueous solution and enhance the acidity of otherwise weakly acidic boric acid (H3BO3) producing mononuclear and binuclear mixed ligand CrIII-borate complexes: [(L)Cr(H2BO4)]- and [(L)Cr(BO4)Cr(L)](1-2)+ respectively through coordination of the H2O and/or OH- ligands, cis-coordinated in the CrIII-complexes on the electron deficient BIII-atom in H3BO3 with release of protons. Deprotonation of the parent CrIII-complexes and their reactions with H3BO3 have been investigated by potentiometric method in aqueous solution, = 0.1 mol dm-3 (NaNO3) at 25 ± 0.1° C. The equilibrium constants have been evaluated by computerized methods and the tentative stoichiometry of the reactions have been worked out on the basis of the speciation curves.

  6. Effect of the ratio of zinc amino acid complex to zinc sulfate on the performance of Holstein cows

    National Research Council Canada - National Science Library

    Nayeri, A; Upah, N C; Sucu, E; Sanz-Fernandez, M V; DeFrain, J M; Gorden, P J; Baumgard, L H

    2014-01-01

    Multiparous (n=70) and primiparous (n=66) Holstein cows were balanced by 305-d previous mature-equivalent milk yield and parity and assigned to 1 of 3 dietary treatments to evaluate the ratio of zinc sulfate to zinc amino acid complex (CZ...

  7. N-Arylation of azaheterocycles with aryl and heteroaryl halides catalyzed by iminodiacetic acid resin-chelated copper complex

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Iminodiacetic acid resin-chelated copper(Ⅱ) complex is effective in cross-coupling reactions between azaheterocycles and aryl or heteroaryl halides,providing N-arylated products in good to excellent yields.The copper catalyst is air stable and can be readily recovered and reused with minimal loss of activity for three runs.

  8. Mitochondrial complex II participates in normoxic and hypoxic regulation of alpha-keto acids in the murine heart.

    NARCIS (Netherlands)

    Muhling, J.; Tiefenbach, M.; Lopez-Barneo, J.; Piruat, J.I.; Garcia-Flores, P.; Pfeil, U.; Gries, B.; Muhlfeld, C.; Weigand, M.A.; Kummer, W.; Weissmann, N.; Paddenberg, R.

    2010-01-01

    alpha-Keto acids (alpha-KAs) are not just metabolic intermediates but are also powerful modulators of different cellular pathways. Here, we tested the hypothesis that alpha-KA concentrations are regulated by complex II (succinate dehydrogenase=SDH), which represents an intersection between the

  9. Mitochondrial complex II participates in normoxic and hypoxic regulation of alpha-keto acids in the murine heart.

    NARCIS (Netherlands)

    Muhling, J.; Tiefenbach, M.; Lopez-Barneo, J.; Piruat, J.I.; Garcia-Flores, P.; Pfeil, U.; Gries, B.; Muhlfeld, C.; Weigand, M.A.; Kummer, W.; Weissmann, N.; Paddenberg, R.

    2010-01-01

    alpha-Keto acids (alpha-KAs) are not just metabolic intermediates but are also powerful modulators of different cellular pathways. Here, we tested the hypothesis that alpha-KA concentrations are regulated by complex II (succinate dehydrogenase=SDH), which represents an intersection between the mitoc

  10. Synthesis and luminescent properties of terbium complex containing 4-benzoylbenzoic acid for application in NUV-based LED

    Institute of Scientific and Technical Information of China (English)

    孙乃群; 赵希瑾; 杨亚敏; 李利平; 张爱琴; 贾虎生; 刘旭光

    2016-01-01

    A novel Tb(III) ternary complex Tb(p-BBA)3MAA was synthesized with 4-benzoylbenzoic acid (p-BBA) and methacrylic acid (MAA) as ligands. The complex was characterized by IR, UV-visible, thermogravimetric analysis and fluorescence spectroscopy. Monitored at 544 nm, the complex displayed wide and strong excitation band at 300–400 nm, which matched well with the 365 nm-emitting UV chip. The complex exhibited excellent green emission at 544 nm (5D4→7F5 transition of Tb3+) under an excitation at 365 nm. Besides, the complex showed high thermal stability. Its intramolecular energy transfer process was further discussed. Fur-thermore, the complex also had higher fluorescence lifetime (1.38 ms) and higher quantum yield (0.372). Finally, electroluminescent properties indicated that when used to fabricate LED with 365 nm UV chip (power efficiency is 18.6 lm/W), the complex remained its favorable optical performance. These results implied that Tb(p-BBA)3MAA could be used as a green phosphor for NUV-based white LED.

  11. Supramolecular Photochirogenesis with a Higher-Order Complex: Highly Accelerated Exclusively Head-to-Head Photocyclodimerization of 2-Anthracenecarboxylic Acid via 2:2 Complexation with Prolinol.

    Science.gov (United States)

    Kawanami, Yuko; Katsumata, Shin-Ya; Nishijima, Masaki; Fukuhara, Gaku; Asano, Kaori; Suzuki, Takeyuki; Yang, Cheng; Nakamura, Asao; Mori, Tadashi; Inoue, Yoshihisa

    2016-09-21

    An unprecedented 2:2 complex was shown to intervene in the enantiodifferentiating photocyclodimerization of 2-anthracenecarboxylic acid (A) mediated by a hydrogen-bonding template l-prolinol (P) to accelerate the formation of chiral anti-head-to-head and achiral syn-head-to-head cyclodimers in >99% combined yield with enhanced enantioselectivities of up to 72% ee for the former. The supramolecular complexation and photochirogenic behaviors, as well as the plausible structures, of intervening Am·Pn complexes (m, n = 1 or 2) were elucidated by combined theoretical and experimental spectroscopic, photophysical, and photochemical studies. Furthermore, the photochemical chiral amplification was achieved for the first time by utilizing the preferential 2:2 complexation of A with homochiral P to give normalized product enantioselectivities higher than those of the template used. The present strategy based on the higher-order hydrogen-bonding motif, which is potentially applicable to a variety of carboxylic acids and β-aminoalcohols, is not only conceptually new and expandable to other (photo)chirogenic and sensing systems but also may serve as a versatile tool for achieving photochemical asymmetric amplification and constructing chiral functional supramolecular architectures.

  12. Solvent Effects on Complexation of Molybdenum(VI) with Nitrilotriacetic Acid in Different Aqueous Solutions of Propanol

    Institute of Scientific and Technical Information of China (English)

    MOHAMMADI Behrouz; MOHAMMADI Jalal

    2007-01-01

    By using spectrophotometric and potentiometric techniques the formation constants of the species formed in the systems H++Mo(VI)+nitrilotriacetic acid and H++nitrilotriacetic acid have been determined in aqueous solutions plex was determined by the continuous variation method. It was shown that molybdenum(VI) forms a mononuclear 1 : 1 complex with nitrilotriacetic acid of the type MoO3L-3 at -1g[H+]=5.8. The formation constants in various media were analyzed in terms of Kamlet and Taft's parameters. Linear relationships were observed when 1g Ks was plotted versus p*. Finally, the results were discussed in terms of the effect of solvent on complexation.

  13. Synthesis, Spectral, and In Vitro Antibacterial Studies of Organosilicon(IV) Complexes with Schiff Bases Derived from Amino Acids.

    Science.gov (United States)

    Singh, Har Lal; Singh, Jangbhadur; Mukherjee, A

    2013-01-01

    The present work stems from our interest in the synthesis, characterization, and antibacterial evaluation of organosilicon(IV) complexes of a class of amino-acid-based Schiff base which have been prepared by the interaction of ethoxytrimethylsilane with the Schiff bases (N OH) in 1 : 1 molar ratio. These complexes have been characterized by elemental analysis, molar conductance, and spectroscopic studies including electronic IR and NMR ((1)H, (13)C, and (29)Si) spectroscopy. The analytical and spectral data suggest trigonal bipyramidal geometry around the silicon atom in the resulting complexes. The ligands and their organosilicon complexes have also been evaluated for in vitro antimicrobial activity against bacteria (Bacillus cereus, Nocardia spp., E. aerogenes, Escherichia coli, Klebsiella spp., and Staphylococcus spp.). The complexes were found to be more potent as compared to the ligands.

  14. Complexation of Am(III) and Nd(III) by 1,10-Phenanthroline-2,9-Dicarboxylic Acid

    Energy Technology Data Exchange (ETDEWEB)

    Ogden, Mark D.; Sinkov, Sergey I.; Nilsson, Mikael; Lumetta, Gregg J.; Hancock, Robert D.; Nash, Ken L.

    2013-01-01

    The complexant 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) is a planar tetradentate ligand that is more preorganized for metal complexation than its unconstrained analogue ethylendiiminodiacetic acid (EDDA). Furthermore, the backbone nitrogen atoms of PDA are aromatic, hence are softer than the aliphatic amines of EDDA. It has been hypothesized that PDA will selectively bond to trivalent actinides over lanthanides. In this report, the results of spectrophotometric studies of the complexation of Nd(III) and Am(III) by PDA are reported. Because the complexes are moderately stable, it was necessary to conduct these titrations using competitive equilibrium methods, competitive cation omplexing between PDA and diethylenetriaminepentaacetic acid, and competition between ligand protonation and complex formation. Stability constants and ligand protonation constants were determined at 0.1 mol/L ionic strength and at 0.5 mol/L ionic strength nitrate media at 21 ± 1 C. The stability constants are lower than those predicted from first principles and speciation calculations indicate that Am(III) selectivity over Nd(III) is less than that exhibited by 1,10-phenanthroline.

  15. Synthesis of Eu(Ⅲ) and Tb(Ⅲ) complexes with novel pyridine dicarboxylic acid derivatives and their fluorescence properties

    Institute of Scientific and Technical Information of China (English)

    Tang Ruiren; Yan Zi'er; Guo Cancheng; Luo Yiming

    2006-01-01

    Starting from pyridine-2,6-dicarboxylic acid (DPA),a series of novel pyridine-2,6-dicarboxylic acid derivatives were synthesized.In these compounds,4-(hydroxymethyl)pyridine-2,6-dicarboxylate (4-HMDPA) and 4-[(bis-carboxymethyl-amino)-methyl] -pyridine-2,6-dicarboxylic acid (4-BMDPA) were used as multifunctional ligands to coordinate with Tb(Ⅲ) and Eu(Ⅲ) and the complexes were prepared.The fluorescence properties of the solid complexes and their solutions were investigated in detail.The results indicated that the weak election-withdrawing group 4-hydroxymethyl in 4-position of pyridine in 4-HMDPA could weaken the fluorescence intensity of the lanthanide complexes.The contradistinctive experimental results showed that the fluorescence intensities of these complexes are related to pH values of the aqueous solutions and the dipole moments of solvent molecules:in the neutral aqueous solutions,the fluorescence intensities of these complexes were strongest,while the dipole moments were lower when the fluorescence intensifies were stronger.4-BMDPA is the better sensitizer and may be used as time-resolved fluoroimmunoassay.

  16. Migration of Cd, Cu, Ni and Pb in low-permeable clay-type solids in presence of acid complexants

    Energy Technology Data Exchange (ETDEWEB)

    Sager, M. [Federal Office and Research Centre of Agriculture, Institute of Agro - Ecology Spargelfeldstrabe, Vienna (Austria)

    1997-12-31

    In order to predict vertical mobility of trace meta ions through low permeable subsurface layers below waste deposition sites, a series of experiments has been carried out; results show that the retardation behaviour of Cu/Cd/Pb/Ni simultaneously and continuously applied to water saturated soil columns together with dilute acids, depends on the the composition of the solid phase as well as the complexing capabilities of the liquid phase. Whereas acetic acid mainly releases Ca + Mg from the solid, oxalic acid can also dissolves large amounts of Fe + Al. The appearance of acid in the eluate is indicative for the penetration of added metals as well, but in some cases, the fastest (Ni) moves much faster than the acid itself. For weakly complexing acetic acid, buffer capacity and releasable Fe seem to be the main factors for the retardation of Cu/Cd/Pb/Ni. Addition of neutral salts (Na{sub 2} SO{sub 4}) lowers the water permeation velocity, and enlarges retardation of the tested cations

  17. Synthesis, characterization and biocidal activity of new organotin complexes of 2-(3-oxocyclohex-1-enyl)benzoic acid.

    Science.gov (United States)

    Vieira, Flaviana T; de Lima, Geraldo M; Maia, José R da S; Speziali, Nivaldo L; Ardisson, José D; Rodrigues, Leonardo; Correa, Ary; Romero, Oscar B

    2010-03-01

    The reaction of 1,3-cyclohexadione with 2-aminobenzoic acid has produced the 2-(3-oxocyclohex-1-enyl)benzoic acid (HOBz). Subsequent reactions of the ligand with organotin chlorides led to [Me(2)Sn(OBz)O](2) (1), [Bu(2)Sn(OBz)O](2) (2), [Ph(2)Sn(OBz)O](2) (3), [Me(3)Sn(OBz)] (4), [Bu(3)Sn(OBz)] (5) and [Ph(3)Sn(OBz)] (6). All complexes have been fully characterized. In addition the structure of complexes (2) and (4) have been authenticated by X-ray crystallography. The biological activity of all derivatives has been screened against Cryptococcus neoformans and Candida albicans. In addition we have performed toxicological testes employing human kidney cell. The complexes (3), (5) and (6) displayed the best values of inhibition of the fungus growing, superior to ketoconazole. Compound (5) presented promising results in view of the antifungal and cytotoxicity assays.

  18. Stereoselective Michael Addition of Glycine Anions to Chiral Fischer Alkenylcarbene Complexes. Asymmetric Synthesis of beta-Substituted Glutamic Acids.

    Science.gov (United States)

    Ezquerra, Jesús; Pedregal, Concepción; Merino, Isabel; Flórez, Josefa; Barluenga, José; García-Granda, Santiago; Llorca, María-Amparo

    1999-09-03

    The reaction of lithium enolates of achiral N-protected glycine esters with chiral alkoxyalkenylcarbene complexes of chromium provided the corresponding Michael adducts with either high anti or syn selectivity depending on the nature of the nitrogen protecting group, and high diastereofacial selectivity when carbene complexes containing the (-)-8-phenylmenthyloxy group were employed. Subsequent oxidation of the metal-carbene moiety followed by deprotection of the amine group and hydrolysis of both carboxylic esters afforded enantiomerically enriched 3-substituted glutamic acids of natural as well as unnatural stereochemistry. Alternatively, when the deprotection step was performed previously to the oxidation, cyclic aminocarbene complexes were formed, which finally led to optically active 3-substituted pyroglutamic acids.

  19. [Effect of the B-group vitamin complex on the blood content of saturated and unsaturated fatty acids in patients with ischemic heart disease and hypertension].

    Science.gov (United States)

    Vodoevich, V P; Buko, V U

    1986-01-01

    Gas-liquid chromatography was used to study the blood content of saturated and unsaturated fatty acids, under the influence of the functionally-associated vitamin-B complex, in 45 patients with coronary heart disease and essential hypertension. The vitamins were given daily in the following doses: thiamine diphosphate 50 mg, riboflavine 40 mg, calcium pantothenate 200 mg, nicotinic acid 200 mg and lipoic acid 50 mg. Favourable shifts leading to positive clinical effects were recorded in the fatty acid metabolism after 10-day taking the vitamin-B complex: the content of unsaturated (linoleic and arachidonic) fatty acids increased while that of saturated (stearic and palmitic) fatty acids decreased.

  20. Complex

    African Journals Online (AJOL)

    CLEMENT O BEWAJI

    Schiff bases and their complex compounds have been studied for their .... establishing coordination of the N–(2 – hydroxybenzyl) - L - α - valine Schiff base ..... (1967); “Spectrophotometric Identification of Organic Compounds”, Willey, New.

  1. Structural Feature and Molecular Interaction of Basic Amino Acid-Picric Acid Complexes by X-Ray Crystal Analyses

    National Research Council Canada - National Science Library

    長田, 裕臣; 尹, 康子; 友尾, 幸司; 土井, 光暢; 石田, 寿昌; 若原, 章男

    1995-01-01

    As a part of elucidating the structural features of a host molecule necessary for the recognition of basic amino acids, the crystal structures of the picrates of DL-arginine (1), L-arginine (2), L-lysine (3), and L-ornitine (4...

  2. Crystal structure of β-cyclodextrin-4-chlorobenzoic acid complex:Unusual C-Cl...π interaction between 4-chlorobenzoic acids in β-cyclodextrin dimer

    Institute of Scientific and Technical Information of China (English)

    En Ju Wang; Guang Ying Chen

    2011-01-01

    The inclusion complex of β-cyclodextrin (β-CD) with 4-chlorobenzoic acid was synthesized and its crystal structure was determined by single crystal X-ray diffraction under cryogenic condition. The complex contains two β-CDs, two 4-chlorobenzoic acids and twenty-nine water molecules in the asymmetric unit, and can be formulated as 2(C42H70O35)-2(C7H5O2Cl)·29(H2O). In the crystal lattice, two β-CDs form a face-to-face dimer jointed together through hydrogen bonding between the secondary hydroxyl groups of β-CDs. Two 4-chlorobenzoic acid molecules which contact by C-Cl…π interactions are included in the β-CD dimer cavity. The β-CD dimers are arranged in brickwork-like pattern along the crystallographic a-axis. The effect of guest molecule length on the inclusion geometry was discussed by comparative study of some β-CD complexes containing similar guests.

  3. Gallic Acid as a Complexing Agent for Copper Chemical Mechanical Polishing Slurries at Neutral pH

    Science.gov (United States)

    Kim, Yung Jun; Kang, Min Cheol; Kwon, Oh Joong; Kim, Jae Jeong

    2011-05-01

    Gallic acid was investigated as a new complexing agent for copper (Cu) chemical mechanical polishing slurries at neutral pH. Addition of 0.03 M gallic acid and 1.12 M H2O2 at pH 7 resulted in a Cu removal rate of 560.73±17.49 nm/min, and the ratio of the Cu removal rate to the Cu dissolution rate was 14.8. Addition of gallic acid improved the slurry performance compared to glycine addition. X-ray photoelectron spectroscopy analysis and contact angle measurements showed that addition of gallic acid enhanced the Cu polishing behavior by suppressing the formation of surface Cu oxide.

  4. Complex toxic effects of Cd2+, Zn2+, and acid rain on growth of kidney bean (Phaseolus vulgaris L).

    Science.gov (United States)

    Liao, Bo-han; Liu, Hong-yu; Zeng, Qing-ru; Yu, Ping-zhong; Probst, Anne; Probst, Jean-Luc

    2005-08-01

    Complex toxic effects of Cd2+, Zn2+, and acid rain on growth of kidney bean (Phaseolus vulgaris L) were studied in a pot experiment by measurement of fresh weights of the plants, determination of surperoxide dismutase (SOD), peroxidase (POD), and lipid peroxidation (MDA) in the plant organs, and observation of injury symptoms. The experimental results demonstrated that all treatments of Cd2+, Zn2+, and/or acid rain significantly decreased fresh weights of kidney bean and caused toxic effects on growth of the plants, especially higher amounts of Cd2+ and Zn2+ and higher acidity of acid rain. Combination of these three pollutant factors resulted in more serious toxic effects than any single pollutant and than combinations of any two pollutants. SOD, POD, and MDA in the plant organs changed with different pollution levels, but MDA content in the leaves showed the best relationship between the pollution levels and toxic effects.

  5. Structure of the human-heart fatty-acid-binding protein 3 in complex with the fluorescent probe 1-anilinonaphthalene-8-sulphonic acid

    Energy Technology Data Exchange (ETDEWEB)

    Hirose, Mika; Sugiyama, Shigeru, E-mail: sugiyama@chem.eng.osaka-u.ac.jp [Lipid Active Structure Project, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan); Osaka University, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan); Ishida, Hanako; Niiyama, Mayumi [Lipid Active Structure Project, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan); Osaka University, 2-1 Yamadaoka, Suita 565-0871 (Japan); Matsuoka, Daisuke; Hara, Toshiaki [Lipid Active Structure Project, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan); Osaka University, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan); Mizohata, Eiichi [Osaka University, 2-1 Yamadaoka, Suita 565-0871 (Japan); Murakami, Satoshi [Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama, Kanagaw 226-8501 (Japan); Inoue, Tsuyoshi [Osaka University, 2-1 Yamadaoka, Suita 565-0871 (Japan); Matsuoka, Shigeru; Murata, Michio [Lipid Active Structure Project, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan); Osaka University, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan)

    2013-11-01

    The crystal structure of human-heart-type fatty-acid-binding protein in complex with anilinonaphthalene-8-sulfonate was solved at 2.15 Å resolution revealing the detailed binding mechanism of the fluorescent probe 1-anilinonaphthalene-8-sulfonate. Heart-type fatty-acid-binding protein (FABP3), which is a cytosolic protein abundantly found in cardiomyocytes, plays a role in trafficking fatty acids throughout cellular compartments by reversibly binding intracellular fatty acids with relatively high affinity. The fluorescent probe 1-anilinonaphthalene-8-sulfonate (ANS) is extensively utilized for examining the interaction of ligands with fatty-acid-binding proteins. The X-ray structure of FABP3 was determined in the presence of ANS and revealed the detailed ANS-binding mechanism. Furthermore, four water molecules were clearly identified in the binding cavity. Through these water molecules, the bound ANS molecule forms indirect hydrogen-bond interactions with FABP3. The adipocyte-type fatty-acid-binding protein (FABP4) exhibits 67% sequence identity with FABP3 and its crystal structure is almost the same as that of FABP3. However, FABP4 can bind with a higher affinity to ANS than FABP3. To understand the difference in their ligand specificities, a structural comparison was performed between FABP3–ANS and FABP4–ANS complexes. The result revealed that the orientation of ANS binding to FABP3 is completely opposite to that of ANS binding to FABP4, and the substitution of valine in FABP4 to leucine in FABP3 may result in greater steric hindrance between the side-chain of Leu115 and the aniline ring of ANS.

  6. Molecular modeling and cytotoxicity of diffractaic acid: HP-β-CD inclusion complex encapsulated in microspheres.

    Science.gov (United States)

    Silva, Camilla V N S; Barbosa, Jéssica A P; Ferraz, Milena S; Silva, Nicácio H; Honda, Neli K; Rabello, Marcelo M; Hernandes, Marcelo Z; Bezerra, Beatriz P; Cavalcanti, Isabella M F; Ayala, Alejandro P; Santos, Noemia P S; Santos-Magalhães, Nereide S

    2016-11-01

    In this pioneer study, 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) was used to improve the solubility of the diffractaic acid (DA) via inclusion complex (DA:HP-β-CD). Subsequently, DA:HP-β-CD was incorporated into poly-ε-caprolactone (PCL) microspheres (DA:HP-β-CD-MS). Microspheres containing DA (DA-MS) or DA:HP-β-CD (DA:HP-β-CD-MS) were prepared using the multiple W/O/W emulsion-solvent evaporation technique. The phase-solubility diagram of DA in HP-β-CD (10-50mM) showed an AL type curve with a stability constant K1:1=821M(-1). (1)H NMR, FTIR, X-ray diffraction and thermal analysis showed changes in the molecular environment of DA in DA:HP-β-CD. The molecular modeling approach suggests a guest-host complex formation between the carboxylic moiety of both DA and the host (HP-β-CD). The mean particle size of the microspheres were ∅DA-MS=5.23±1.65μm and ∅DA:HP-β-CD-MS=4.11±1.39μm, respectively. The zeta potential values of the microspheres were ζDA-MS=-7.85±0.32mV and ζDA:HP-β-CD-MS=-6.93±0.46mV. Moreover, the encapsulation of DA:HP-β-CD into microspheres resulted in a more slower release (k2=0.042±0.001; r(2)=0.996) when compared with DA-MS (k2=0.183±0.005; r(2)=0.996). The encapsulation of DA or DA:HP-β-CD into microspheres reduced the cytotoxicity of DA (IC50=43.29μM) against Vero cells (IC50 of DA-MS=108.48μM and IC50 of DA:HP-β-CD-MS=142.63μM).

  7. Equilibrium, thermoanalytical and spectroscopic studies to characterize phytic acid complexes with Mn(II) and Co(II)

    Energy Technology Data Exchange (ETDEWEB)

    Carli, Ligia de; Schnitzler, Egon; Rosso, Neiva Deliberali [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil). Dept. de Quimica], e-mail: ndrosso@uepg.br; Ionashiro, Massao [Universidade Estadual Paulista (UNESP), Araraquara, SP (Brazil). Inst. de Quimica; Szpoganicz, Bruno [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Quimica

    2009-07-01

    Potentiometric studies were carried out to determine the binding degree of phytic acid with Co(II) and Mn(II) ions, in the absence of dioxygen. Equilibrium constants for all major complexes formed are reported, and the results are presented in the form of distribution diagrams showing the concentrations of individual complexes as a function of pH. The formation constants of the complexes show higher values for the species in which the ligand was more deprotonated. Potentiometric data indicates that the species [MH{sub 4}L]{sup 6-}, was totally formed at pH 7.0 and the complexes were synthesized from this data. A solid state complex of Mn(II) and Co(II) with phytic acid was synthesized. Thermogravimetry, differential scanning calorimetry, and infrared spectroscopy were used to investigate and characterize the thermal behavior of these compounds. The results led to information on the composition, dehydration, thermal stability and thermal decomposition of the isolated complexes. (author)

  8. Asynchronous Reductive Release of Iron and Organic Carbon from Hematite-Humic Acid Complexes

    Science.gov (United States)

    Adhikari, D.; Poulson, S.; Sumaila, S.; Dynes, J.; McBeth, J. M.; Yang, Y.

    2015-12-01

    Association with solid-phase iron plays an important role in the accumulation and stabilization of soil organic matter (SOM). Ferric minerals are subject to redox reactions, which can compromise the stability of iron-bound SOM. To date, there is limited information available concerning the fate of iron-bound SOM during redox reactions. In this study, we investigated the release kinetics of hematite-bound organic carbon (OC) during the abiotic reduction of hematite-humic acid (HA) complexes by dithionite, as an analog for the fate of iron-bound SOM in natural redox reactions. Carbon 1s near edge X-ray absorption fine structure (NEXAFS) spectroscopy was used to examine the ratio of the aromatic, phenolic and carboxylic/imide functional groups of the adsorbed OC before and after reduction. Our results indicate that the reductive release of iron obeyed first-order kinetics with release rate constants of 6.67×10-3 to 13.0×10-3 min-1. The iron-bound OC was released rapidly during the initial stage with release rate constants of 0.011 to 1.49 min-1, and then became stable with residual fractions of 4.6% to 58.2% between 120 and 240 min. The release rate of aromatic OC was much faster than for the non-aromatic fraction of HA, and 90% of aromatic OC was released within the first hour for most samples. The more rapid release of aromatic OC was attributed to its potential distribution on the outer layer because of steric effects and the possible reduction of quinoids. Our findings show that in the reductive reaction the mobilization of iron-bound organic carbon was asynchronous with the reduction of iron, and aromatic carbon was released more readily than other organic components. This study illustrates the importance of evaluating the stability of iron-bound SOM, especially under aerobic-anaerobic transition conditions.

  9. Construction and Evaluation of a Targeted Hyaluronic Acid Nanoparticle/Photosensitizer Complex for Cancer Photodynamic Therapy.

    Science.gov (United States)

    Gao, Shi; Wang, Jingjing; Tian, Rui; Wang, Guohao; Zhang, Liwen; Li, Yesen; Li, Lu; Ma, Qingjie; Zhu, Lei

    2017-09-12

    Photodynamic therapy (PDT) is a novel treatment modality that is under intensive preclinical investigations for a variety of diseases, including cancer. Despite extensive studies in this area, selective and effective photodynamic agents that can specifically accumulate in tumors to reach a therapeutic concentration are limited. Although recent attempts have produced photosensitizers (PSs) complexed with various nanomaterials, the tedious preparation steps and poor tumor efficiency of therapy hamper their utilization. Here, we developed a CD44-targeted nanophotodynamic agent by physically encapsulating a photosensitizer, Ce6, into a hyaluronic acid nanoparticle (HANP), which was hereby denoted HANP/Ce6. Its physical features and capability for photodynamic therapy were characterized in vitro and in vivo. Systemic delivery of HANP/Ce6 resulted in its accumulation in a human colon cancer xenograft model. The tumor/muscle ratio reached 3.47 ± 0.46 at 4 h post injection, as confirmed by fluorescence imaging. Tumor growth after HANP/Ce6 treatment with laser irradiation (0.15 W/cm(2), 630 nm) was significantly inhibited by 9.61 ± 1.09-fold compared to that in tumor control groups, which showed no change in tumor growth. No apparent systemic and local toxic effects on the mice were observed. HANP/Ce6-mediated tumor growth inhibition was accessed and observed for the first time by (18)F-fluoro-2-deoxy-d-glucose positron emission tomography as early as 1 day after treatment and persisted for 14 days within our treatment time window. In sum, our results highlight the imaging properties and therapeutic effects of the novel HANP/Ce6 theranostic nanoparticle for CD44-targeted PDT cancer therapy that may be potentially utilized in the clinic. This HANP system may also be applied for the delivery of other hydrophobic PSs, particularly those that could not be chemically modified.

  10. Electrochemicla Behavior of Ascorbic Acid on Hexaaza Macrocyclic Copper(II) Complex Modified Au Electrode and Its Analytical Application

    Institute of Scientific and Technical Information of China (English)

    WU,Hai-Xia; DONG,Shu-Qing; KANG,Jing-Wan; LU,Xiao-Quan

    2008-01-01

    A novel hexaaza macrocyclic copper(II) complex modified Au electrode was developed and used for the measurement of ascorbic acid. Its electrochemical behavior was investigated by cyclic voltammetry and scanning electrochemical microscopy. This modified electrode exhibited electrocatalytic response to the oxidation of ascorbic acid. Compared with a bare gold electrode, the modified electrode exhibited a 250 mV shift of the oxidation potential of ascorbic acid in the cathodic direction and a marked enhancement of the current response. The response current revealed a good linear relationship with the concentration of ascorbic acid in the range of 5.0×10-7 to 4.0× 10-5 mol/L and the detection limit of 4.8× 10-8 mol/L (S/N=3) in the pH 4.0 Tris-HCl buffer of ascorbic acid in fruits without any other pretreatment. The concentrations of ascorbic acid measured by this method were in good agreement with the literature values. It is very promising for the modified electrode to be used as an electrochemical sensor for the detection of ascorbic acid.

  11. In-Situ ATR-FTIR and Surface Complexation Modeling Study of the Adsorption of Dimethylarsenic Acid and p-Arsanilic Acid on Iron Oxides

    Science.gov (United States)

    Goldberg, S. R.; Al-Abadleh, H.; Mitchell, W.

    2010-12-01

    Arsenic is an element that exists naturally in many rocks and minerals around the world, accumulates in petroleum, shale, and coal deposits as a result of biogeochemical processes, and is found in fly ash from fuel combustion. Arsenic compounds in their organic and inorganic forms pose both health and environmental risks. The environmental fate of arsenic compounds is controlled to a large extent by their surface interactions with inorganic and organic surfaces. We report results from applying the triple layer surface complexation model to adsorption isotherm and pH-envelope experimental data of dimethylarsenic acid, DMA, and p-arsanilic acid, p-AsA on the iron oxides, hematite and goethite. Ligand exchange reactions were based on the interpretation of ATR-FTIR spectra of DMA and p-AsA surface complexes. Surface coverage of the organoarsenicals was quantified in-situ from the spectral component at 840 cm-1. The best model fit to the DMA adsorption data was obtained using an outer-sphere complex, whereas for p-AsA, best model fit was obtained using two monodentate inner-sphere surface complexes. The significance of the results is discussed in relation to improving modeling tools used by environmental regulators. Accurate predictive modeling tools are needed for effective design of arsenic removal technologies using iron oxide minerals.

  12. In situ ATR-FTIR and surface complexation modeling studies on the adsorption of dimethylarsinic acid and p-arsanilic acid on iron-(oxyhydr)oxides.

    Science.gov (United States)

    Mitchell, William; Goldberg, Sabine; Al-Abadleh, Hind A

    2011-06-15

    Arsenic is an element that exists naturally in many rocks and minerals around the world. It also accumulates in petroleum, shale, oil sands, and coal deposits as a result of biogeochemical processes, and it has been found in fly ash from the combustion of solid biofuels. Arsenic compounds in their organic and inorganic forms pose both a health and an environmental risk, and continue to be a challenge to the energy industry. The environmental fate and removal technologies of arsenic compounds are controlled to a large extent by their surface interactions with inorganic and organic adsorbents. We report thermodynamic binding constants, K(binding), from applying the triple-layer surface complexation model to adsorption isotherm and pH envelope data for dimethylarsinic acid (DMA) and p-arsanilic acid (p-AsA) on hematite and goethite. Ligand exchange reactions were constructed based on the interpretation of ATR-FTIR spectra of DMA and p-AsA surface complexes. Surface coverage of adsorbates was quantified in situ from the spectral component at 840 cm(-1). The best fit to the DMA adsorption data was obtained using outer-sphere complex formation, whereas for p-AsA, the best fit was obtained using two monodentate inner-sphere surface complexes. The significance of the results is discussed in relation to improving modeling tools used by environmental regulators and the energy sector for optimum control of arsenic content in fuels.

  13. Spectroscopic and physical measurements on charge-transfer complexes: Interactions between norfloxacin and ciprofloxacin drugs with picric acid and 3,5-dinitrobenzoic acid acceptors

    Science.gov (United States)

    Refat, Moamen S.; Elfalaky, A.; Elesh, Eman

    2011-03-01

    Charge-transfer complexes formed between norfloxacin (nor) or ciprofloxacin (cip) drugs as donors with picric acid (PA) and/or 3,5-dinitrobenzoic acid (DNB) as π-acceptors have been studied spectrophotometrically in methanol solvent at room temperature. The results indicated the formation of CT-complexes with molar ratio1:1 between donor and acceptor at maximum CT-bands. In the terms of formation constant ( KCT), molar extinction coefficient ( ɛCT), standard free energy (Δ Go), oscillator strength ( f), transition dipole moment (μ), resonance energy ( RN) and ionization potential ( ID) were estimated. IR, H NMR, UV-Vis techniques, elemental analyses (CHN) and TG-DTG investigations were used to characterize the structural of charge-transfer complexes. It indicates that the CT interaction was associated with a proton migration from each acceptor to nor or cip donors which followed by appearing intermolecular hydrogen bond. In addition, X-ray investigation was carried out to scrutinize the crystal structure of the resulted CT-complexes.

  14. Hepatoprotective Activity of a Complex Compound of 5-Hydroxy-6-Methyluracil and Succinic Acid in Experimental Peritonitis

    Directory of Open Access Journals (Sweden)

    D. A. Yenikeyev

    2008-01-01

    Full Text Available Objective: to evaluate the hepatoprotective efficacy of a complex compound of 5-hydroxy-6-methyluracil and succinic acid in experimental peritonitis. Materials and methods. Experiments were carried out on 48 male albino rats in which peritonitis was simulated via intraperitoneal administration of 7% fecal suspension in a dose of 0.6 ml per 100 g bodyweight. The rate of free radical oxidation processes, the activity of antioxidative protection, the degree of endogenous intoxication and cytolytic syndrome, and the effect of the test compound on these parameters were estimated in the experiment. Results. With the development of an abdominal inflammatory process, there were increases in rates of endogenous intoxication and free radical oxidation (FRO, a change in the activity of antioxidative protection enzymes, and a reduction in the levels of ceruloplasmin and sulfahydryl groups. The complex compound, that comprised 5-hydroxy-6-methyluracil and succinic acid used as monotherapy, reduced the degree of endogenous intoxication, FRO, and lipid peroxidation-antioxidative defense system imbalance. Conclusion. The experimental data suggest that the use of the complex compound containing succinic acid and 5-hydroxy-6-methy-luracil is pathogenetically warranted. Key words: peritonitis, lipid peroxidation, antioxidants, succinic acid, pyrim-idine derivatives.

  15. Crystal Structure of a Novel Sandwich Inclusion Complex of β-Cyclodextrin with a-Naphthylacetic Acid

    Institute of Scientific and Technical Information of China (English)

    WANG En-ju; CHEN Guang-ying; HAN Chang-ri

    2011-01-01

    A supramolecular inclusion complex between β-cyclodextrin(β-CD) and a-naphthylacetic acid was prepared,and its crystal structure was investigated by single-crystal X-ray crystallography The complex contains two β-CD molecules,one a-naphthylacetic acid,two ethanols and twenty-eight water molecules in the asymmetric unit,which could be formulated as [(C42H70O35)2·(C12H10O2)·(C2H5OH)2·28H2O].Two β-CD molecules constitute a dimer by face-to-face contact of their secondary hydroxyl sides.At the interface of the dimer,one a-naphthylacetic acid molecule is sandwiched between two β-CD molecules.Each β-CD unit of the dimer includes one ethanol molecule in its cavity.The β-CD dimers are linked together via hydrogen bonding to form layers that are stacked in a brickwork-like pattern.The comparative study of some sandwich complexes elucidates that the interface of the β-CD dimer has a stronger inclusion capacity than the cavity of β-CD for some suitable planar guest molecules.The novel inclusion structure results from the competitive inclusion of a-naphthylacetic acid and ethanol.

  16. Feasibility of antibody-poly(glutamic acid) complexes: preparation of high-concentration antibody formulations and their pharmaceutical properties.

    Science.gov (United States)

    Izaki, Shunsuke; Kurinomaru, Takaaki; Maruyama, Takuya; Uchida, Takayuki; Handa, Kenji; Kimoto, Tomoaki; Shiraki, Kentaro

    2015-06-01

    Development of high-concentration antibody formulations for subcutaneous administration remains challenging. Recently, a precipitation-redissolution method was proposed to prepare suspensions or precipitates of salt-dissociable protein-poly(amino acid) complexes. To elucidate the utility of this method for protein therapy, we investigated the feasibility of a precipitation-redissolution method using poly(amino acid) for high-concentration antibody formulation. Omalizumab and adalimumab formulations of 150 mg/mL could be prepared using poly-l-glutamic acid (polyE) from low-concentration stock solutions. Enzyme-linked immunosorbent assay, circular dichroism, and size-exclusion chromatography revealed that the formation of antibody-polyE complex and precipitation-redissolution process did not significantly affect the immunoreactivity or secondary structure of the antibodies. The precipitation-redissolution method was less time-consuming and more effective than lyophilization-redissolution, evaporation-redissolution, and ultrafiltration from the viewpoint of final yield. Scalability was confirmed from 400 μL to 1.0 L. The general toxicity and pharmacokinetic profiles of the antibody-polyE complex formulations were similar to those of conventional antibody formulations. These results suggested that the precipitation-redissolution method using poly(amino acid) has great potential as a concentration method for antibody formulation and medicinal use.

  17. Structural and thermodynamic study of rare earth(III) complexation by poly-hydroxylated carboxylic acids: synthesis of new extractants and outlook for the extraction of these cations; Etude structurale et thermodynamique de la complexation de lanthanides (III) par des acides carboxyliques polyhydroxyles: synthese de nouveaux extractants et perspectives pour l'extraction de ces cations

    Energy Technology Data Exchange (ETDEWEB)

    Aury, S

    2002-12-15

    The aim of this work is: to improve the knowledge on the binding sites of the poly-hydroxylated carboxylic acids with the trivalent lanthanide(III) ions by comparing them to gluconic acid (previously studied) and to molecules with different configuration and with a variable number of OH functions (threonic acid, glyceric acid, 2-hydroxy-butanoic acid, 3-hydroxy-butanoic acid). To find the best complexing agent among different acids (aldonic acids, aldaric acids, di-hydroxybenzoic acids) (determination of the set of complexes and their stability constants by potentiometry, NMR and UV-Visible spectroscopy). To synthesize hydrophobic monoamides from one lactone form of saccharic acid, to study their complexing power and their capacity to extract the trivalent lanthanide(III) ions. (author)

  18. Complexation of trichlorosalicylic acids by alkaline and first row transition metals as a switch for their antibacterial activity

    KAUST Repository

    Kumar, Vijay

    2017-09-14

    3,5,6-trichlorosalicylic acid (TCSA) does not show a good antibacterial activity. In contrast, here metal complexes with TCSA have shown better antibacterial activity for selected bacterial strains with a good degree of selectivity. Amongst the eight synthesized essential metal complexes complexed with TCSA, Mn(II)-TCSA and Ni(II)-TCSA have been found to be more effective with MIC range 20-50 µg/L as compared to control (chloramphenicol). The activity of an individual complex against different microbes was not found to be identical, indicating the usage of an individual metal chelate against a targeted bacterial strain. Further, the protein (BSA) binding constant of TCSA and its metal complexes were determined and ordered as Ca(II)-TCSA > Cu(II)-TCSA > Mg(II)-TCSA >> Mn(II)-TCSA >> Zn(II)-TCSA >>> Ni(II)-TCSA >>> Co(II)-TCSA > Fe(II)-TCSA > TCSA. The present study has confirmed enhanced antibacterial activities and binding constants for metal chelates of TCSA as compared to free TCSA, which seems directly related with the antioxidant activities of these complexes. Further, bearing the ambiguity related to the structural characterization of the metal complexed with TCSA ligands, DFT calculations have been used as the tool to unravel the right environment around the metals, studying basically the relative stability of square planar and octahedral metal complexes with TCSA.

  19. Thermochemical analysis on rare earth complex of gadolinium with salicylic acid and 8-hydroxyquinoline

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Sheng-Xiong, E-mail: 54xsx@163.com [Hunan Provincial Key Laboratory of Rare-Precious Metals Compounds and Applications, Department of Chemistry and Life Science, Xiangnan University, Chenzhou 423000, Hunan Province (China); Li, Ai-Tao; Jiang, Jian-Hong; Huang, Shuang; Xu, Xiao-Yan; Li, Qiang-Guo [Hunan Provincial Key Laboratory of Rare-Precious Metals Compounds and Applications, Department of Chemistry and Life Science, Xiangnan University, Chenzhou 423000, Hunan Province (China)

    2012-11-20

    Highlights: Black-Right-Pointing-Pointer A new novel rare earth complex Gd(C{sub 7}H{sub 5}O{sub 3}){sub 2}{center_dot}(C{sub 9}H{sub 6}NO) was synthesized and characterized. Black-Right-Pointing-Pointer The dissolution enthalpies of the relevant substances were determined. Black-Right-Pointing-Pointer The enthalpy change of the reaction was determined to be (211.54 {+-} 0.69) kJ mol{sup -1}. Black-Right-Pointing-Pointer The standard molar enthalpy of formation of complex was -(1890.7 {+-} 3.1) kJ mol{sup -1}. - Abstract: The rare earth complex, Gd(C{sub 7}H{sub 5}O{sub 3}){sub 2}{center_dot}(C{sub 9}H{sub 6}NO), was synthesized by the reaction of Gadolinium nitrate hexahydrate with salicylic acid (C{sub 7}H{sub 6}O{sub 3}) and 8-hydroxyquinoline (C{sub 9}H{sub 7}NO). And it was characterized by elemental analysis, UV spectra, IR spectra, molar conductance and thermogravimetric analysis. In a optimalizing calorimetric solvent, the dissolution enthalpies were determined by an advanced solution-reaction isoperibol microcalorimeter, respectively: {Delta}{sub s}H{sub m}{sup {Theta}} [2 C{sub 7}H{sub 6}O{sub 3}(s) + C{sub 9}H{sub 7}NO(s), 298.15 K] = 41.95 {+-} 0.44 kJ mol{sup -1}, {Delta}{sub s}H{sub m}{sup {Theta}} [Gd(NO{sub 3}){sub 3}{center_dot}6H{sub 2}O(s), 298.15 K] = -29.11 {+-} 0.39 kJ mol{sup -1}, {Delta}{sub s}H{sub m}{sup {Theta}} [Gd(C{sub 7}H{sub 5}O{sub 3}){sub 2}{center_dot}(C{sub 9}H{sub 6}NO)(s), 298.15 K] = -46.99 {+-} 0.39 kJ mol{sup -1} and {Delta}{sub s}H{sub m}{sup {Theta}} [Solution D(aq), 298.15 K] = -90.33 {+-} 0.37 kJ mol{sup -1}. The enthalpy change of the synthesized reaction was estimated to be {Delta}{sub r}H{sub m}{sup {Theta}}=211.54{+-}0.69 kJ mol{sup -1}. From data in the literature, through Hess' law, the standard molar enthalpy of formation of Gd(C{sub 7}H{sub 5}O{sub 3}){sub 2}{center_dot}(C{sub 9}H{sub 7}NO)(s) was calculated to be {Delta}{sub f}H{sub m}{sup {Theta}} [Gd(C{sub 7}H{sub 5}O{sub 3}){sub 2}{center_dot}(C{sub 9}H

  20. Mono and binuclear ruthenium(II) complexes containing 5-chlorothiophene-2-carboxylic acid ligands: Spectroscopic analysis and computational studies

    Science.gov (United States)

    Swarnalatha, Kalaiyar; Kamalesu, Subramaniam; Subramanian, Ramasamy

    2016-11-01

    New Ruthenium complexes I, II and III were synthesized using 5-chlorothiophene-2-carboxylic acid (5TPC), as ligand and the complexes were characterized by elemental analysis, FT-IR, 1H, 13C NMR, and mass spectroscopic techniques. Photophysical and electrochemical studies were carried out and the structures of the synthesized complex were optimized using density functional theory (DFT). The molecular geometry, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) energies and Mulliken atomic charges of the molecules are determined at the B3LYP method and standard 6-311++G (d,p) basis set starting from optimized geometry. They possess excellent stabilities and their thermal decomposition temperatures are 185 °C, 180 °C and 200 °C respectively, indicating that the metal complexes are suitable for the fabrication processes of optoelectronic devices.

  1. Preparation and characterization of solidified oleanolic acid–phospholipid complex aiming to improve the dissolution of oleanolic acid

    Directory of Open Access Journals (Sweden)

    Xiaoxu Yang

    2016-04-01

    Full Text Available The purpose of this study was to prepare the oleanolic acid–phospholipid complex (OA-PC and then solidify it employing fumed silica by simple solvent evaporation technique to improve dissolution rate of oleanolic acid and oleanolic acid–phospholipid complex. The process of OA-PC was optimized and the type and proportion of fumed silica were studied by dissolution text. The structures of the phospholipid complex and solidified powder were also characterized by differential scanning calorimetry, X-ray diffraction, and scanning electron microscope. In the dissolution tests, OA from solidified powder was further released compared with that from pure OA and OA-PC in different kinds of dissolution media. These results suggest that the method of preparing solidified powder of oleanolic acid–phospholipid complex is suitable for enhancing the dissolution rate of OA and OA-PC.

  2. Copper(II) complexes of bis(amino amide) ligands: effect of changes in the amino acid residue.

    Science.gov (United States)

    Martí, Inés; Ferrer, Armando; Escorihuela, Jorge; Burguete, M Isabel; Luis, Santiago V

    2012-06-14

    A family of ligands derived from bis(amino amides) containing aliphatic spacers has been prepared, and their protonation and stability constants for the formation of Cu(2+) complexes have been determined potentiometrically. Important differences are associated to both the length of the aliphatic spacer and the nature of the side chains derived from the amino acid. In general, ligands containing aliphatic side chains display higher basicities as well as stability constants with Cu(2+). In the same way, basicities and stability constants tend to increase when decreasing the steric hindrance caused by the corresponding side-chain. FT-IR, UV-vis and ESI-MS were used for analyzing the complex species detected in the speciation diagram. UV-vis studies showed the presence of different coordination environments for the copper(II) complexes. Complexes with different stoichiometries can be formed in some instances. This was clearly highlighted with the help of ESI-MS experiments.

  3. Hydrolysis of p-Nitrophenyl Picolinate Catalyzed by Mono-and Binuclear Transition Metal Complexes with Polyether Bridged Dihydroxamic Acid

    Institute of Scientific and Technical Information of China (English)

    李建章; 李鸿波; 冯发美; 谢家庆; 李慎新; 周波; 秦圣英

    2005-01-01

    Two polyether bridged dihydroxamic acids and their mono-and binuclear manganese(Ⅱ), zinc(Ⅱ) complexes have been synthesized and employed as models to mimic hydrolase in catalytic hydrolysis of p-nitrophenyl picolinate (PNPP). The reaction kinetics and the mechanism of hydrolysis of PNPP have been investigated. The kinetic mathematical model for PNPP cleaved by the complexes has been proposed. The effects of the different central metal ion, mono-and binuclear metal, the pseudo-macrocyclic polyether constructed by polyethoxy group of the complexes, and reactive temperature on the rate for catalytic hydrolysis of PNPP have been examined. The results showed that the transition metal dthydroxamates exhibited high catalytic activity to the hydrolysis of PNPP, the catalytic activity of binuclear complexes was higher than that of mononuclear ones, and the pseudo-macrocyclic polyether might synergetically activate H20 coordinated to metal ion with central metal ion together and promote the catalytic hydrolysis of PNPP.

  4. Cu(II) complexation by "non-coordinating" N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES buffer).

    Science.gov (United States)

    Sokołowska, Magdalena; Bal, Wojciech

    2005-08-01

    The combined potentiometric and spectroscopic studies of interactions of N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) with Cu(II) demonstrated that this popular buffer, commonly labelled as "non-coordinating" forms a CuL+ complex, with the logbeta(CuL) value of 3.22. This complex undergoes alkaline hydrolysis above pH 6, resulting in Cu(OH)2 precipitation. However, the presence of HEPES at a typical concentration of 100 mM at pH 7.4 elevates the apparent binding constant, being determined for a complex of another ligand, by a factor of 80. HEPES does not form ternary complexes with aminoacids Ala, Trp, and His, but may do so with other bioligands, such as nucleotides. Therefore, HEPES can still be recommended for Cu(II) studies in place of other common buffers, such as Tris and phosphate, but appropriate corrections and precautions should be applied in quantitative experiments.

  5. Synthesis of New Azo Dyes and Copper(II) Complexes Derived from Barbituric Acid and 4-Aminobenzoylhydrazone

    OpenAIRE

    GUP, Bülent KIRKAN and Ramazan

    2008-01-01

    Four new azo dyes, L1, L2, L3, and L4, were prepared by linking benzaldehyde p-aminobenzoylhydrazone (3) and p-hydroxybenzaldehyede p--aminobenzoylhydrazone (4) to barbituric acid and 1,3-dimethylbarbituric acid through diazo-coupling reactions. Reactions of the azo-dyes with copper chloride and bidentate ligand, 1,10-phenanthroline, produced mixed-ligand dinuclear complexes with general stoichiometry [Cu2L(phen)2]Cl2 (7, 8, 9, and 10). The structures of both azo dyes and their compl...

  6. Separation and Detection of Lanthanide Ions with Nitrilotri (methylenephosphonic) Acid as Complexing Agent and Eluent by IPC

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A mixture containing eleven lanthanide ions was separated and detected on an anion-exchange co-lumn by ion chromatography with indirect photometry detection (IPC).An aqueous solution of 1.5×10-2mol/L nitrilotri(methylenephosphonic) acid and 2.5×10-3mol/L tiron was used as the eluent in which the former served as complexing agent and eluent,the latter played as color reagent and eluent.The effects of acidity,concentration and composition of eluent on the retention behavior of the analytes and detection sensitivity are discussed.

  7. Palladium-phosphinous acid complexes catalyzed Suzuki cross-coupling reaction of heteroaryl bromides with phenylboronic acid in water/alcoholic solvents

    Institute of Scientific and Technical Information of China (English)

    Ben Li; Cuiping Wang; Guang Chen; Zhiqiang Zhang

    2013-01-01

    Highly active,air-stable and water-soluble palladium-phosphinous acid complexes have been applied to Suzuki cross-coupling reaction of heteroaryl bromides under mild conditions in water/alcoholic solvents.Suzuki cross-coupling reaction of heteroaryl bromides with phenylboronic acid occurred efficiently using palladium phosphinous acid complexes (POPd) and phase transfer catalyst (tetrabutylammonium bromide and polyethylene glycol) in water/ethanol mixture,water/propanol mixture and neat water respectively,the corresponding yields of cross-coupling heteroaryl-aryls were satisfied.The tert-butyl substituted ligand di-tert-butylphosphino in combination with POPd was found to be more active than the same family derived catalysts dipalladium complexes POPdl and POPd2,and other two kinds of Pd-catalysts Pd(PPh3)4 and Pd2(dba)3.The mechanism of Suzuki cross-coupling reaction between heteroaryl bromides and phenylboronic acid in water was proposed with respect to the key role of phase transfer catalyst on the transmetallation step.Compared with other solid phase transfer catalysts,TBAB was tested as the ideal one.The alkalinity of base and the molar proportion between POPd and TBAB were investigated in water and alcoholic solvents.Notably,in the presence of TBAB adding alcoholic solvents into water enhanced the yields of target products.However in terms of the liquid phase transfer catalyst of PEGs,mixing water into PEGs could slightly decrease the yields with respect to the water free PEGs bulk phase,which was probably due to the homogenous liquid conditions in pure PEGs and weak interactions between PEGs and heteroaryl bromide molecules in water depending on their molecular chain lengths.

  8. Palladium-phosphinous acid complexes catalyzed Suzuki cross-coupling reaction of heteroaryl bromides with phenylboronic acid in water/alcoholic solvents.

    Science.gov (United States)

    Li, Ben; Wang, Cuiping; Chen, Guang; Zhang, Zhiqiang

    2013-06-01

    Highly active, air-stable and water-soluble palladium-phosphinous acid complexes have been applied to Suzuki cross-coupling reaction of heteroaryl bromides under mild conditions in water/alcoholic solvents. Suzuki cross-coupling reaction of heteroaryl bromides with phenylboronic acid occurred efficiently using palladium phosphinous acid complexes (POPd) and phase transfer catalyst (tetrabutylammonium bromide and polyethylene glycol) in water/ethanol mixture, water/propanol mixture and neat water respectively, the corresponding yields of cross-coupling heteroaryl-aryls were satisfied. The tert-butyl substituted ligand di-tert-butylphosphino in combination with POPd was found to be more active than the same family derived catalysts dipalladium complexes POPd1 and POPd2, and other two kinds of Pd-catalysts Pd(PPh3)4 and Pd2(dba)3. The mechanism of Suzuki cross-coupling reaction between heteroaryl bromides and phenylboronic acid in water was proposed with respect to the key role of phase transfer catalyst on the transmetallation step. Compared with other solid phase transfer catalysts, TBAB was tested as the ideal one. The alkalinity of base and the molar proportion between POPd and TBAB were investigated in water and alcoholic solvents. Notably, in the presence of TBAB adding alcoholic solvents into water enhanced the yields of target products. However in terms of the liquid phase transfer catalyst of PEGs, mixing water into PEGs could slightly decrease the yields with respect to the water free PEGs bulk phase, which was probably due to the homogenous liquid conditions in pure PEGs and weak interactions between PEGs and heteroaryl bromide molecules in water depending on their molecular chain lengths.

  9. Synthesis, crystal structure and antitumor effect of a novel copper(II) complex bearing zoledronic acid derivative.

    Science.gov (United States)

    Qiu, Ling; Lv, Gaochao; Guo, Liubin; Chen, Liping; Luo, Shineng; Zou, Meifen; Lin, Jianguo

    2015-01-07

    A great majority of Cu(II) complexes currently studied in the anticancer research field exert their antiproliferative activities through ligand exchange. In this work, we present the synthesis and structural characterization of two novel Cu(II) complexes, {[Cu3(ZL)2(H2O)6]·6H2O}n (1) (ZL = 1-hydroxy-2-(1H-imidazol-1-yl)ethane-1,1-diyldiphosphonic acid) and [Cu(IPrDP)2]·3H2O (2) (IPrDP = 1-hydroxy-3-(1H-imidazol-1-yl)propane-1,1-diyldiphosphonic acid). Due to the insolubility of polymer 1 in common solvents, only the biological activities of complex 2 were investigated. The antitumor activity of complex 2 was evaluated against a panel of human cancer cell lines, including U2OS, A549, HCT116, MDA-MB-231 and HepG2. Complex 2 exhibited comparable cytotoxic effect to cisplatin (CDDP) against the human colon carcinoma cells HCT116, and superior selectivity for inhibiting human hepatocarcinoma cells rather than normal liver cells. The cell cycle distribution analysis indicates that complex 2 inhibits human carcinoma cells by inducing the cell cycle arrest at the G2/M phase, showing a similar mechanism of action to that of CDDP. The binding interaction of complex 2 with calf thymus DNA (CT-DNA) has been explored by UV-vis absorption and circular dichroism (CD), demonstrating complex 2 has a moderate binding affinity for DNA through intercalation.

  10. Effective DNA binding and cleaving tendencies of malonic acid coupled transition metal complexes

    Science.gov (United States)

    Pravin, Narayanaperumal; Utthra, Ponnukalai Ponya; Kumaravel, Ganesan; Raman, Natarajan

    2016-11-01

    Eight transition metal complexes were designed to achieve maximum biological efficacy. They were characterized by elemental analysis and various other spectroscopic techniques. The monomeric complexes were found to espouse octahedral geometry and non-electrolytic nature. The DNA interaction propensity of the complexes with calf thymus DNA (CT-DNA), studied at physiological pH by spectrophotometric, spectrofluorometric, cyclic voltammetry, and viscometric techniques revealed intercalation as the possible binding mode. Fascinatingly, the complexes were found to exhibit greater binding strength than that of the free ligands. A strong hypochromism and a slight red shift were exhibited by complex 5 among the other complexes. The intrinsic binding constant values of all the complexes compared to cisplatin reveal that they are excellent metallonucleases than that of cisplatin. The complexes were also shown to reveal displacement of the ethidium bromide, a strong intercalator using fluorescence titrations. Gel electrophoresis was used to divulge the competence of the complexes in cleaving the supercoiled pBR322 plasmid DNA. From the results, it is concluded that the complexes, especially 5, are excellent chemical nucleases in the presence of H2O2. Furthermore, the in vitro antimicrobial screening of the complexes exposes that these complexes are excellent antimicrobial agents. Overall the effect of coligands is evident from the results of all the investigations.

  11. Analysis of putative nonulosonic acid biosynthesis pathways in Archaea reveals a complex evolutionary history.

    Science.gov (United States)

    Kandiba, Lina; Eichler, Jerry

    2013-08-01

    Sialic acids and the other nonulosonic acid sugars, legionaminic acid and pseudaminic acid, are nine carbon-containing sugars that can be detected as components of the glycans decorating proteins and other molecules in Eukarya and Bacteria. Yet, despite the prevalence of N-glycosylation in Archaea and the variety of sugars recruited for the archaeal version of this post-translational modification, only a single report of a nonulosonic acid sugar in an archaeal N-linked glycan has appeared. Hence, to obtain a clearer picture of nonulosonic acid sugar biosynthesis capability in Archaea, 122 sequenced genomes were scanned for the presence of genes involved in the biogenesis of these sugars. The results reveal that while Archaea and Bacteria share a common route of sialic acid biosynthesis, numerous archaeal nonulosonic acid sugar biosynthesis pathway components were acquired from elsewhere via various routes. Still, the limited number of Archaea encoding components involved in the synthesis of nonulosonic acid sugars implies that such saccharides are not major components of glycans in this domain.

  12. ENVIRONMENTALLY FRIENDLY COMPLEXONES. THE THERMODYNAMIC CHARACTERISTICS OF THE FORMATION OF AL3+ ION COMPLEXES WITH ETHYLENEDIAMINEDISUCCINIC ACID IN AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    L.N. Tolkacheva

    2012-06-01

    Full Text Available Complex formation between Al3+ and ethylenediamine - N,N`-disuccinic acid (H4L was studied at 25°C against the background of 0.1, 0.5, 1.0 N solutions of KNO3 by potentiometry and mathematical modeling. The extrapolation of concentration constants to zero ionic strength was used to calculate the thermodynamic constants of the formation of the AlL–, AlHL complexes using an equation with one individual parameter (logβ0 = 16.27 ± 0.07, 9.19 ± 0.2 respectively.

  13. Catalytic Oxidative Decarboxylation of Some Benzylcarboxylic Acid Derivatives by a New Iron(Ill) Schiff Base Complex

    Institute of Scientific and Technical Information of China (English)

    MONTAZEROZOHORI,Morteza; NASR-ESFAHANI,Masoud; AKHLAGHI,Parisa

    2009-01-01

    A quadridentate Schiff base ligand of N,N'-bis(2-hydroxy-a-methylbenzylidene)ethylenediamine (HMBEDA) and its new iron(Ⅲ) complex were synthesized and identified by analytical, spectral data (1H NMR, 13C NMR FT-IR and UV-visible) and molar conductance. A rapid and efficient homogeneous oxidative decarboxylatio n ofsome benzylcarboxylic acid derivatives was carried out by a catalytic amount of iron(Ⅲ) Schiff base complex in chloroform, using tetrabutylammonium periodate as a mild oxidant in good to excellent yields at room temperature.

  14. Design, synthesis and evaluation of a new Mn - Contrast agent for MR imaging of myocardium based on the DTPA-phenylpentadecanoic acid complex

    Science.gov (United States)

    Belyanin, Maxim L.; Stepanova, Elena V.; Valiev, Rashid R.; Filimonov, Victor D.; Usov, Vladimir Y.; Borodin, Oleg Y.; Ågren, Hans

    2016-11-01

    In the present paper we describe the first synthesis and evaluation of a novel Mn (II) complex (DTPA-PPDA Mn (II)) which contains a C-15 fatty acid moiety that has high affinity to the heart muscle. The complexation energy of DTPA-PPDA Mn (II) evaluated by quantum chemistry methodology indicates that it essentially exceeds the corresponding value for the known DTPA Mn (II) complex. Molecular docking revealed that the affinity of the designed complex to the heart-type transport protein H-FABP well exceeds that of lauric acid. Phantom experiments in low-field MRI the designed contrast agent provides MR imaging comparable to gadopentetic acid.

  15. Formation of molecular complexes of salicylic acid, acetylsalicylic acid, and methyl salicylate in a mixture of supercritical carbon dioxide with a polar cosolvent

    Science.gov (United States)

    Petrenko, V. E.; Antipova, M. L.; Gurina, D. L.; Odintsova, E. G.

    2015-08-01

    The solvate structures formed by salicylic acid, acetylsalicylic acid, and methyl salicylate in supercritical (SC) carbon dioxide with a polar cosolvent (methanol, 0.03 mole fractions) at a density of 0.7 g/cm3 and a temperature of 318 K were studied by the molecular dynamics method. Salicylic and acetylsalicylic acids were found to form highly stable hydrogen-bonded complexes with methanol via the hydrogen atom of the carboxyl group. For methyl salicylate in which the carboxyl hydrogen is substituted by a methyl radical, the formation of stable hydrogen bonds with methanol was not revealed. The contribution of other functional groups of the solute to the interactions with the cosolvent was much smaller. An analysis of correlations between the obtained data and the literature data on the cosolvent effect on the solubility of the compounds in SC CO2 showed that the dissolving ability of SC CO2 with respect to a polar organic substance in the presence of a cosolvent increased only when stable hydrogen-bonded complexes are formed between this substance and the cosolvent.

  16. X-Ray Crystallographic Analysis, EPR Studies, and Computational Calculations of a Cu(II) Tetramic Acid Complex

    Science.gov (United States)

    Matiadis, Dimitrios; Tsironis, Dimitrios; Stefanou, Valentina; Igglessi–Markopoulou, Olga; McKee, Vickie; Sanakis, Yiannis; Lazarou, Katerina N.

    2017-01-01

    In this work we present a structural and spectroscopic analysis of a copper(II) N-acetyl-5-arylidene tetramic acid by using both experimental and computational techniques. The crystal structure of the Cu(II) complex was determined by single crystal X-ray diffraction and shows that the copper ion lies on a centre of symmetry, with each ligand ion coordinated to two copper ions, forming a 2D sheet. Moreover, the EPR spectroscopic properties of the Cu(II) tetramic acid complex were also explored and discussed. Finally, a computational approach was performed in order to obtain a detailed and precise insight of product structures and properties. It is hoped that this study can enrich the field of functional supramolecular systems, giving place to the formation of coordination-driven self-assembly architectures. PMID:28316540

  17. The Cell Wall Teichuronic Acid Synthetase (TUAS Is an Enzyme Complex Located in the Cytoplasmic Membrane of Micrococcus luteus

    Directory of Open Access Journals (Sweden)

    Lingyi Lynn Deng

    2010-01-01

    composed of disaccharide repeating units [-4-β-D-ManNAcAp-(1→6α-D-Glcp−1-]n, which is covalently anchored to the peptidoglycan on the inner cell wall and extended to the outer surface of the cell envelope. An enzyme complex responsible for the TUA chain biosynthesis was purified and characterized. The 440 kDa enzyme complex, named teichuronic acid synthetase (TUAS, is an octomer composed of two kinds of glycosyltransferases, Glucosyltransferase, and ManNAcA-transferase, which is capable of catalyzing the transfer of disaccharide glycosyl residues containing both glucose and the N-acetylmannosaminuronic acid residues. TUAS displays hydrophobic properties and is found primarily associated with the cytoplasmic membrane. The purified TUAS contains carotinoids and lipids. TUAS activity is diminished by phospholipase digestion. We propose that TUAS serves as a multitasking polysaccharide assembling station on the bacterial membrane.

  18. Capillary Electrophoresis for the Simultaneous Determination of Metals by Using Ethylenediamine Tetraacetic Acid as Complexing Agent and Vancomycin as Complex Selector

    Institute of Scientific and Technical Information of China (English)

    THREEPROM, Jirasak; SOM-AUM, Waraporn; LIN, Jin-Ming

    2006-01-01

    A new separation system of capillary electrophoresis for the simultaneous determination of metals by using ethylenediamine tetraacetic acid (EDTA) as complexing agent and employing vancomycin as complex selector was described. The Z-shape cell capillary electrophoresis was used to enhance the sensitivity for the determination of the complexes of Cu(Ⅱ), Ni(Ⅱ), Co(Ⅱ) and Fe(Ⅲ) with EDTA. The partial filling method (co-current mode) was used in order to increase the selectivity of the electrophoretic method, meanwhile vancomycin was not present at the detector path during the detection of metal-EDTA complexes. The vancomycin concentration, phosphate concentration and pH of the buffer strongly influenced mobility, resolution and selectivity of the studied analytes. Under the optimal condition, the relative standard deviations (n=5) of the migration time and the peak area were less than 3.14% and 7.35%, respectively. Application of the Z-shape cell capillary electrophoresis method with UV detection and vancomycin loading led to the reliable determination of these metal ions in tap water and the recoveries were 97%-101%. The detection limits based on a signal to noise ratio of 3: 1 were found in the range of 2-10 μg·L-1.

  19. Equilibrium CH acidity of Ni(II) complexes of Schiff's bases of amino acids with S-2-N-(N'-benzylprolyl)amino-benzaldehyde and S-2-N-(N'-benzylprolyl)aminobenzophenone

    Energy Technology Data Exchange (ETDEWEB)

    Terekhova, M.I.; Belokon' , Yu.N.; Maleev, V.I.; Chernoglazova, N.I.; Kochetkov, K.A.; Belikov, V.M.; Petrov, E.S.

    1986-10-20

    By metal exchange in DMSO (K/sup +/ cation) pK values have been measured for a series of acids which are Ni(II) complexes of Schiff's bases of the amino acids Gly, S-Ala, and S-Val, with S-2-N-(N'-benzylprolyl)aminobenzaldehyde and S-2-N-(N'-benzylprolyl)aminobenzophenone. The amino acid fragment in the studied Ni(II) complexes possesses high acidity close to fluorene but five orders of magnitude greater than for acetophenone and approaching nitroalkanes in acidity.

  20. Formation of Complex Amino Acid Precursors in Simulated Primitive Atmosphere and Their Alteration under Simulated Submarine Hydrothermal Conditions

    Science.gov (United States)

    Kobayashi, Kensei; Kurihara, Hironari; Hirako, Tomoaki; Obayashi, Yumiko; Kaneko, Takeo; Takano, Yoshinori; Yoshimura, Yoshitaka

    Since late 1970's a great number of submarine hydrothermal systems (SHSs) has been dis-covered, and they are considered possible sites of chemical evolution and generation of life on the Earth since their discovery in late 1970s. A number of experiments simulating the con-ditions of SHSs were conducted, and abiotic production and polymerization of amino acids were reported. Free amino acids were frequently used as starting materials to examine possible organic reactions in the simulation experiments. In our early studies, not free amino acids but complex amino acids precursors with large molecular weights were formed abiotically from simulated primitive Earth atmosphere (a mixture of CO, N2 and H2 O) (Takano et al., 2004). Such complex organics (hereafter referred as to CNWs) should have been delivered to SHSs in Primitive Ocean, where they were subjected to further alteration. We examined possible alteration of the complex organics in high-temperature high-pressure environments by the su-percritical water flow reactor (SCWFR) (Islam et al.. 2003) and an autoclave. CNWs were quite hydrophilic compounds whose molecular weights were ca. 3000. After heating 573 K for 2 min in the SCWFR, aggregates of organics were formed, which were separated from aque-ous solution with a Nucleopore filter (pore size: 200 nm). We propose the following scenario of chemical evolution: (1) Complex organics including amino acid precursors were formed in primitive atmosphere and/or extraterrestrial environments, (ii) they were delivered to primor-dial SHSs, (iii) hydrothermal alteration occurred in SHSs to give organic aggregates, (iv) quite primitive molecular systems with subtle biological functions were generated in the competition among such aggregates. References: Islam, Md. N., Kaneko, T., and Kobayashi, K (2003). Reactions of Amino Acids with a Newly ConstructedSupercritical Water Flow Reactor Simulating Submarine Hydrothermal Systems. Bull. Chem. Soc. Jpn., 76, 1171. Takano, Y

  1. The fifth solvatomorph of gallic acid with a supramolecular channel structure: Structural complexity and phase transitions

    Science.gov (United States)

    Thomas, Sajesh P.; Kaur, Ramanpreet; Kaur, Jassjot; Sankolli, Ravish; Nayak, Susanta K.; Guru Row, Tayur N.

    2013-01-01

    A new solvatomorph of gallic acid was generated using chiral additive technique and characterized by single crystal and powder X-ray diffraction, C-13 NMR, IR spectroscopic techniques and thermal analysis. The supramolecular channels formed by hexameric motifs of gallic acid and solvent molecules contain highly disordered solvent molecules with fractional occupancies.

  2. Separation of complex mixtures of amino acids for biorefinery applications using electrodialysis

    NARCIS (Netherlands)

    Kattan-Readi, O.M.; Girones nogue, M.; Nijmeijer, D.C.

    2013-01-01

    The potential of electrodialysis (ED) for the separation of amino acids (zwitterionic molecules that exhibit a specific charge behavior dependent on pH) has been demonstrated in the past. However, even though successful for the separation of specific amino acids, ED is not applicable for the separat

  3. The complex tale of the high oleic acid trait in peanut (Arachis hypogaea L.)

    Science.gov (United States)

    Fatty acid composition of oil extracted from peanut (Arachis hypogaea L.) seed is an important quality trait. In particular, a high ratio of oleic (C18:1) relative to linoleic (C18:2) fatty acid (O/L = 10) results in a longer shelf life. Previous reports suggest that the high oleic (~80%) trait wa...

  4. Dual hydrogen-bonding motifs in complexes formed between tropolone and formic acid

    Science.gov (United States)

    Nemchick, Deacon J.; Cohen, Michael K.; Vaccaro, Patrick H.

    2016-11-01

    The near-ultraviolet π*←π absorption system of weakly bound complexes formed between tropolone (TrOH) and formic acid (FA) under cryogenic free-jet expansion conditions has been interrogated by exploiting a variety of fluorescence-based laser-spectroscopic probes, with synergistic quantum-chemical calculations built upon diverse model chemistries being enlisted to unravel the structural and dynamical properties of the pertinent ground [X˜ 1A'] and excited [A˜ 1A'(" separators="π*π )] electronic states. For binary TrOH ṡ FA adducts, the presence of dual hydrogen-bond linkages gives rise to three low-lying isomers designated (in relative energy order) as INT, EXT1, and EXT2 depending on whether docking of the FA ligand to the TrOH substrate takes place internal or external to the five-membered reaction cleft of tropolone. While the symmetric double-minimum topography predicted for the INT potential surface mediates an intermolecular double proton-transfer event, the EXT1 and EXT2 structures are interconverted by an asymmetric single proton-transfer process that is TrOH-centric in nature. The A ˜ -X ˜ origin of TrOH ṡ FA at ν˜ 00=27 484 .45 cm-1 is displaced by δ ν˜ 00=+466 .76 cm-1 with respect to the analogous feature for bare tropolone and displays a hybrid type - a/b rotational contour that reflects the configuration of binding. A comprehensive analysis of vibrational landscapes supported by the optically connected X˜ 1A' and A˜ 1A'(" separators="π*π ) manifolds, including the characteristic isotopic shifts incurred by partial deuteration of the labile TrOH and FA protons, has been performed leading to the uniform assignment of numerous intermolecular (viz., modulating hydrogen-bond linkages) and intramolecular (viz., localized on monomer subunits) degrees of freedom. The holistic interpretation of all experimental and computational findings affords compelling evidence that an external-binding motif (attributed to EXT1), rather than the

  5. Thermochemical Study on Coordination Complex of Samarium with Salicylic Acid and 8-Hydroxyquinoline

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The coordination complex Sm(C7H5O3)2·(C9H6NO), synthesized from the reaction of samarium chloride six-hydrate with salicylic acid and 8-hydroxyquinoline, was characterized with IR, elemental analysis, molar conductance, and thermogravimatric analysis. The standard molar enthalpies of solution of [SmCl3·6H2O(s)], [2C7H6O3(s)], [C9H7NO(s)] and [Sm(C7H5O3)2·(C9H6NO)(s)] in the calorimetric solvent were determined with the solution-reaction isoperibol calorimeter at 298.15 K to be ΔsHΘm[SmCl3·6H2O (s), 298.15 K]=-103.98±0.04 kJ·mol-1, ΔsHΘm[2 C7H6O3 (s), 298.15 K]=16.35±0.14 kJ·mol-1, ΔsHΘm[C9H7NO (s), 298.15 K]=-6.11±0.08 kJ·mol-1 and ΔsHΘm[Sm(C7H5O3)2·(C9H6NO) (s), 298.15 K]=-130.08±0.04 kJ·mol-1, respectively. The enthalpy was determined to be ΔrHΘm=89.59±0.18 kJ·mol-1 for the reaction SmCl3·6H2O(s)+2C7H6O3(s)+C9H7NO(s)=Sm(C7H5O3)2·(C9H6NO)(s)+3HCl(g)+6H2O(l). According to the above results and the data given in literature and through Hess' law, the standard molar enthalpy of formation of Sm(C7H5O3)2·(C9H7NO)(s) was estimated to be ΔrHΘm[Sm(C7H5O3)2·(C9H6NO)(s), 298.15 K]=-2055.9±3.03 kJ·mol-1.

  6. Diagnostic value of nine nucleic acid amplification test systems for Mycobacterium tuberculosis complex

    Directory of Open Access Journals (Sweden)

    Gülnur Tarhan

    2015-09-01

    Full Text Available Objective: In this study, nine commercial Nucleic Acid Amplification Test Systems (NAATs were evaluated for diagnostic performance of Mycobacterium tuberculosis complex (MTBC from smear positive sputum species (SPss and smear negative sputum specimens (SNss. Methods: Sixty SPss and 55 SNss were examined icroscopically by Ehrlich Ziehl Neelsen (EZN staining method, and also inoculated on Löwenstein Jensen (LJ medium for culture. The sensitivity and specificity of nine NAATs were calculated according to LJ culture method accepted as gold standard. Results: When LJ culture results were taken as gold standard; the sensitivity rates of method COBAS Amplicor MTB (Method A, GenProbe MTD (Method B, Cobas TaqMan MTB PCR Method C, iCycler iQ RT PCR (Method D, TaqMan PCR AB 5700 (Method E, TaqMan PCR AB7700 (Method F, ightCycler® 480 RT PCR (Method G, Rotor Gene RT PCR (Method H and the AdvanSure TB/NTM RT PCR (Method I for SPss were 98.3 %, 93.3 %, 96.7 %, 100 %, 93.3 %, 100 %, 100 %, 100 % and 100 %, respectively. The sensitivity was 53.84% for the methods A, B, D, E, G and I; 38.46% for the method C and H; 61.5% for the method F for the method I in SNss. There were no statistical significant differences between the nine NAATs (p≥0.05. The specificity was 100% for all nine NAATs in SNss. The positivity rates of methods were 53.8% for methods A, B, D, E, G, I; 38.5% for methods C and H, and 61.5% for method F in SNss. These rates were 100% for D, F, G, H and I; 98.3% for method A; 96.7% for method C; 93,3% for methods B and E in SPss. Statistical analysis showed that there was no statistically significant differences among the nine NAATs (p≥0.05. Conclusion: It is concluded that the nine NAATs might be useful for detecting MTBC from SPss, but not effective for SNss. J Microbiol Infect Dis 2015;5(3: 103-109

  7. Effect of Solvent Dielectric Constant and Acidity on the OH Vibration Frequency in Hydrogen-Bonded Complexes of Fluorinated Ethanols.

    Science.gov (United States)

    Pines, Dina; Keinan, Sharon; Kiefer, Philip M; Hynes, James T; Pines, Ehud

    2015-07-23

    Infrared spectroscopy measurements were used to characterize the OH stretching vibrations in a series of similarly structured fluoroethanols, RCH2OH (R = CH3, CH2F, CHF2, CF3), a series which exhibits a systematic increase in the molecule acidity with increasing number of F atoms. This study, which expands our earlier efforts, was carried out in non-hydrogen-bonding solvents comprising molecules with and without a permanent dipole moment, with the former solvents being classified as polar solvents and the latter designated as nonpolar. The hydrogen bond interaction in donor-acceptor complexes formed in solution between the fluorinated ethanol H-donors and the H-acceptor base DMSO was investigated in relation to the solvent dielectric and to the differences ΔPA of the gas phase proton affinities (PAs) of the conjugate base of the fluorinated alcohols and DMSO. We have observed that νOH decreases as the acidity of the alcohol increases (ΔPA decreases) and that νOH varies inversely with ε, exhibiting different slopes for nonpolar and polar solvents. These 1/ε slopes tend to vary linearly with ΔPA, increasing with increasing acidity. These experimental findings, including the ΔPA trends, are described with our recently published two-state Valence Bond-based theory for acid-base H-bonded complexes. Lastly, the correlation of the alcohol's conjugate base PAs with Taft σ* values of the fluorinated ethyl groups CH(n)F(3-n)CH2- provides a connection of the inductive effects for these groups with the acidity parameter ΔPA associated with the H-bonded complexes.

  8. Combination of redox-active ligand and lewis acid for dioxygen reduction with π-bound molybdenum-quinonoid complexes.

    Science.gov (United States)

    Henthorn, Justin T; Lin, Sibo; Agapie, Theodor

    2015-02-04

    A series of π-bound Mo-quinonoid complexes supported by pendant phosphines have been synthesized. Structural characterization revealed strong metal-arene interactions between Mo and the π system of the quinonoid fragment. The Mo-catechol complex (2a) was found to react within minutes with 0.5 equiv of O(2) to yield a Mo-quinone complex (3), H(2)O, and CO. Si- and B-protected Mo-catecholate complexes also react with O(2) to yield 3 along with (R(2)SiO)n and (ArBO)(3) byproducts, respectively. Formally, the Mo-catecholate fragment provides two electrons, while the elements bound to the catecholate moiety act as acceptors for the O(2) oxygens. Unreactive by itself, the Mo-dimethyl catecholate analogue reduces O(2) in the presence of added Lewis acid, B(C(6)F(5))(3), to generate a Mo(I) species and a bis(borane)-supported peroxide dianion, [[(F(5)C(6))(3)B](2)O(2)(2-)], demonstrating single-electron-transfer chemistry from Mo to the O(2) moiety. The intramolecular combination of a molybdenum center, redox-active ligand, and Lewis acid reduces O(2) with pendant acids weaker than B(C(6)F(5))(3). Overall, the π-bound catecholate moiety acts as a two-electron donor. A mechanism is proposed in which O(2) is reduced through an initial one-electron transfer, coupled with transfer of the Lewis acidic moiety bound to the quinonoid oxygen atoms to the reduced O(2) species.

  9. A Metal-Amino Acid Complex-Derived Bifunctional Oxygen Electrocatalyst for Rechargeable Zinc-Air Batteries.

    Science.gov (United States)

    Ding, Yanjun; Niu, Yuchen; Yang, Jia; Ma, Liang; Liu, Jianguo; Xiong, Yujie; Xu, Hangxun

    2016-10-01

    Bifunctional oxygen electrocatalyst: A metal-amino acid complex is developed to prepare high-performance mesoporous carbon electrocatalyst for both oxygen reduction and oxygen evolution reactions. Such prepared catalyst can be used to assemble rechargeable zinc-air batteries with excellent durability. This work represents a new route toward low-cost, highly active, and durable bifunctional electrocatalysts for cutting-edge energy conversion devices.

  10. Dissociations of copper(II)-containing complexes of aromatic amino acids: radical cations of tryptophan, tyrosine, and phenylalanine.

    Science.gov (United States)

    Siu, Chi-Kit; Ke, Yuyong; Guo, Yuzhu; Hopkinson, Alan C; Siu, K W Michael

    2008-10-14

    The dissociations of two types of copper(II)-containing complexes of tryptophan (Trp), tyrosine (Tyr), or phenylalanine (Phe) are described. The first type is the bis-amino acid complex, [Cu(II)(M)(2)].(2+), where M = Trp, Tyr, or Phe; the second [Cu(II)(4Cl-tpy)(M)].(2+), where 4Cl-tpy is the tridendate ligand 4'-chloro-2,2':6',2''-terpyridine. Dissociations of the Cu(ii) bis-amino acid complexes produce abundant radical cation of the amino acid, M.(+), and/or its secondary products. By contrast, dissociations of the 4Cl-tpy-bearing ternary complexes give abundant M.(+) only for Trp. Density functional theory (DFT) calculations show that for Tyr and Phe, amino-acid displacement reactions by H(2)O and CH(3)OH (giving [Cu(II)(4Cl-tpy)(H(2)O)].(2+) and [Cu(II)(4Cl-tpy)(CH(3)OH)].(2+)) are energetically more favorable than dissociative electron transfer (giving M.(+) and [Cu(I)(4Cl-tpy)](+)). The fragmentation pathway common to all these [Cu(II)(4Cl-tpy)(M)].(2+) ions is the loss of NH(3). DFT calculations show that the loss of NH(3) proceeds via a "phenonium-type" intermediate. Dissociative electron transfer in [Cu(II)(4Cl-tpy)(M-NH(3))].(2+) results in [M-NH(3)].(+). The [Phe-NH(3)] (+) ion dissociates facilely by eliminating CO(2) and giving a metastable phenonium-type ion that rearranges readily into the styrene radical cation.

  11. Influence of humic acid on plutonium sorption to gibbsite. Determination of Pu-humic acid complexation constants and ternary sorption studies

    Energy Technology Data Exchange (ETDEWEB)

    Zimmerman, Trevor; Powell, Brian A. [Clemson Univ., Anderson, SC (United States). Environmental Engineering and Earth Sciences; Zavarin, Mavrik [Lawrence Livermore National Laboratory, Livermore, CA (United States). Glenn T. Seaborg Institute

    2014-10-01

    In this work stability constants describing Pu(IV), Th(IV), and Np(V) binding to Leonardite humic acid (HA) were determined using a discrete pK{sub a} model. A hybrid ultra-filtration/equilibrium dialysis, ligand exchange technique was used to generate the partitioning data. Ethylenediaminetetraacetic acid (EDTA) was used as a reference ligand to allow the aqueous chemistry of the Pu(IV)-HA system to be examined over a range of pH values, while minimizing the possibility of precipitation of Pu(IV). The conditional stability constant for Pu(IV) complexation with HA determined as part of this work is logβ{sub 112} = 6.76 ± 0.14 based on the equation: Pu{sup 4+} + HL3 + 2H{sub 2}O <-> Pu(OH){sub 2}L3{sup +} + 3H{sup +} where HA is represented by HL3 (a binding site on the HA with a pK{sub a} value of 7). This value is three orders of magnitude higher than the Th(IV)-HA constant and between six and eight orders of magnitude higher than the Np(V)-HA complex. The magnitude of the stability constants and the general trend of increasing complexation strength with increasing pH is consistent with previous observations. The Pu(IV)-HA stability constants were used to model sorption of Pu(IV) to gibbsite in the presence of HA. Assuming only aqueous Pu-HA complexes and AlOH-Pu surface complexes, the model was unable to predict the observed data which exhibited greater sorption at pH 4 relative to pH 6; a phenomenon which does not occur in the absence of HA. Therefore, this study demonstrates that ternary Pu-HA-gibbsite complexes may form under low pH conditions and exhibit greater sorption than that observed in the absence of HA. Although the presence of HA may increase the solubility/aqueous concentrations of Pu in the absence of a solid phase, formation of ternary complexes may indeed retard the subsurface migration of Pu. The corollary to this finding is that increased mobility may occur if the ternary surface complex forms on a mobile colloid rather than part of the

  12. Complex Formation Between Lysozyme and Stabilized Micelles with a Mixed Poly(ethylene oxide)/Poly(acrylic acid) Shell.

    Science.gov (United States)

    Karayianni, Maria; Gancheva, Valeria; Pispas, Stergios; Petrov, Petar

    2016-03-10

    The electrostatic complexation between lysozyme and stabilized polymeric micelles (SPMs) with a poly(acrylic acid) (PAA) or a mixed poly(ethylene oxide)/poly(acrylic acid) (PEO/PAA) shell (SPMs with a mixed shell, SPMMS) and a temperature-responsive poly(propylene oxide) (PPO) core was investigated by means of dynamic, static, and electrophoretic light scattering. The SPMs and different types of SPMMS used resulted from the self-assembly of PAA-PPO-PAA triblock copolymer chains, or PAA-PPO-PAA and PEO-PPO-PEO triblock copolymer chain mixtures (with varying chain lengths and molar ratios) in aqueous solutions at pH 10 and the subsequent cross-linking of their PPO cores via loading and photo-cross-linking of pentaerythritol tetraacrylate (PETA). The solution behavior, structure and properties of the formed complexes at pH 7 and 0.01 M ionic strength, were studied as a function of the protein concentration in the solution (the concentration of the stabilized micelles was kept constant) or equivalently the ratio of the two components. The complexation process and properties of the complexes proved to be dependent on the protein concentration, while of particular interest was the effect of the structure of the shell of the SPMs on the stability/solubility of the complexes. Finally, the fluorescence and mid infrared spectroscopic investigation of the structure of the complexed protein showed that, although a small stretching of the protein molecules occurred in some cases, no protein denaturation takes place upon complexation.

  13. Limitations when use chloramphenicol-bcyclodextrins complexes in ophtalmic solutions buffered with boric acid/borax system

    Directory of Open Access Journals (Sweden)

    Todoran Nicoleta

    2014-12-01

    Full Text Available Chloramphenicol eye drops are commonly prescribed in concentrations of 0.5-1% in the treatment of infectious conjunctivitis. In terms of ophthalmic solution preparation, the major disadvantage of chloramphenicol consists in its low solubility in water. The solubility is increased by substances that form chloramphenicol-complexes, for example: boric acid/borax or cyclodextrins. Objective: Experimental studies aimed to evaluate the potential advantages of enhancing the solubility and stability of chloramphenicol (API by molecular encapsulation in b-cyclodextrin (CD, in formulation of ophthalmic solutions buffered with boric acid/borax system. Methods and Results: We prepared four APIb- CD complexes, using two methods (kneading and co-precipitation and two molar ratio of API/b-cyclodextrin (1:1 and 1:2. The formation of complexes was proved by differential scanning calorimetry (DSC and the in vitro dissolution tests. Using these compounds, we prepared eight ophthalmic solutions, formulated in two variants of chloramphenicol concentrations (0.4% and 0.5%. Each solution was analyzed, by the official methods, at preparation and periodically during three months of storing in different temperature conditions (4°C, 20°C and 30°C. Conclusions: Inclusion of chloramphenicol in b-cyclodextrin only partially solves the difficulties due to the low solubility of chloramphenicol. The protection of chloramphenicol molecules is not completely ensured when the ophthalmic solutions are buffered with the boric acid/borax system.

  14. Fe-tannic acid complex dye as photo sensitizer for different morphological ZnO based DSSCs

    Science.gov (United States)

    Çakar, Soner; Özacar, Mahmut

    2016-06-01

    In this paper we have synthesized different morphological ZnO nanostructures via microwave hydrothermal methods at low temperature within a short time. We described different morphologies of ZnO at different Zn(NO3)2/KOH mole ratio. The ZnO nanostructures were characterized via X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and UV-vis spectrophotometry. All ZnO structures have hexagonal wurtzite type structures. The FESEM images showed various morphologies of ZnO such as plate, rod and nanoparticles. Dye sensitized solar cells have been assembled by these different morphological structures photo electrode and tannic acid or Fe-tannic acid complex dye as sensitizer. We have achieved at maximum efficiencies of photovoltaic cells prepared with ZnO plate in all dye systems. The conversion efficiencies of dye sensitized solar cells are 0.37% and 1.00% with tannic acid and Fe-tannic acid complex dye, respectively.

  15. Synthesis, thermodynamic properties and antibacterial activities of lanthanide complexes with 3,5-dimethoxybenzoic acid and 1,10-phenanthroline

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jun-Ru [Testing and Analysis Center, Hebei Normal University, Shijiazhuang 050024 (China); College of Chemistry and Material Science, Hebei Normal University, Shijiazhuang 050024 (China); Ren, Shu-Xia [Material Science and Engineering School, Shijiazhuang Tiedao University, Shijiazhaung 050043 (China); Ren, Ning [Department of Chemistry, Handan College, Handan 056005 (China); Zhang, Jian-Jun, E-mail: jjzhang6@126.com [Testing and Analysis Center, Hebei Normal University, Shijiazhuang 050024 (China); College of Chemistry and Material Science, Hebei Normal University, Shijiazhuang 050024 (China); Zhang, Da-Hai [Department of Chemistry, Handan College, Handan 056005 (China); Wang, Shu-Ping [College of Chemistry and Material Science, Hebei Normal University, Shijiazhuang 050024 (China)

    2013-11-20

    Graphical abstract: Four novel complexes ([Ln(3,5-DmeoxBA){sub 3}(phen)]{sub 2} (Ln = Tb(1), Dy(2), Er(3), Yb(4); 3,5-DmeoxBA = 3,5-dimethoxybenzoic acid; phen = 1,10-phenanthroline))were synthesized and characterized by elemental analysis, IR and TG/DSC-FTIR technology. Heat capacities of the four complexes were measured by differential scanning calorimetry (DSC). The antibacterial action of the four complexes on bacteria and fungus such as Escherichia coli, Staphylococcus aureus and Candida albicans were studied by filter paper approach. - Highlights: • Four novel complexes ([Ln(3,5-DmeoxBA){sub 3}(phen)]{sub 2} were synthesized and characterized. • The thermal decomposition processes of the title complexes were studied using the TG/DSC–FTIR coupling techniques. • The heat capacities of the complexes were measured by (DSC). • The antibacterial action of the four complexes on Escherichia coli, Staphylococcus aureus and Candida albicans were studied. - Abstract: Four lanthanide complexes with a general formula [Ln(3,5-DmeoxBA){sub 3}(phen)]{sub 2} (Ln = Tb(1), Dy(2), Er(3), Yb(4); 3,5-DmeoxBA = 3,5-dimethoxybenzoic acid; phen = 1,10-phenanthroline) were synthesized and characterized by elemental analysis, infrared spectra (IR), and thermogravimetric, differential scanning calorimetry techniques, combined with Fourier transform infrared (TG/DSC–FTIR) technology. The thermal decomposition processes of the four complexes were investigated by TG/DSC–FTIR techniques. Heat capacities were measured by DSC. The values of the experimental heat capacities were fitted to a polynomial equation with the least-squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions (H{sub T} − H{sub 298.15} {sub K}), (S{sub T} − S{sub 298.15} {sub K}), and (G{sub T} − G{sub 298.15} {sub K}) were calculated. The antibacterial action of the four complexes on bacteria and fungus such as Escherichia coli, Staphylococcus aureus and

  16. Thermodynamics of inclusion complexes of natural and modified cyclodextrins with acetylsalicylic acid and ibuprofen in aqueous solution at 298 K

    Energy Technology Data Exchange (ETDEWEB)

    Castronuovo, Giuseppina, E-mail: giuseppina.castronuovo@unina.it [Department of Chemistry, University Federico II of Naples, Complesso Universitario a Monte S. Angelo, via Cintia, 80126 Naples (Italy); Niccoli, Marcella [Department of Chemistry, University Federico II of Naples, Complesso Universitario a Monte S. Angelo, via Cintia, 80126 Naples (Italy)

    2013-04-10

    Graphical abstract: Complexation forces acting in the association between natural and modified α- and β-cyclodextrins and acetylsalicylic acid (aspirin) or ibuprofen are examined through the analysis of the thermodynamic parameters obtained by isothermal calorimetry. Highlights: ► A calorimetric method is reported to study the association of natural and substituted cyclodextrins with acetylsalicylic acid and ibuprofen. ► The study aims to propose a hypothesis about the forces involved in the interaction. That can be useful for designing new cyclodextrins having suitable characteristics to include specific drugs. ► Enthalpic and entropic contributions on the association are discussed. The differences in the cavity dimensions of the cyclodextrins determine the values of the thermodynamic properties to be very different. - Abstract: Thermodynamic parameters for the association of natural and substituted α-, β-, and γ-cyclodextrins with acetylsalicylic acid, salicylic acid and ibuprofen have been determined by isothermal titration calorimetry. Analysis of the data shows that complexes form, all having 1:1 stoichiometry. The shape-matching between the host and guest is the factor determining the values of the thermodynamic quantities. In the case of the smallest cyclodextrin interacting with acetylsalicylic acid and salicylic acid, the parameters indicate that hydrophobic interactions play the major role. Association occurs through the shallow inclusion of the benzene ring into the cavity. In the case of substituted β-cyclodextrins, instead, inclusion of the benzene ring is deeper and the tight fitting of the guest molecule to the cavity makes the enthalpy and entropy to be both negative. Ibuprofen interacts through its isobutyl group: the values of the association constants are very high for β-cyclodextrins as determined by the large and positive entropies due to the relaxation of water molecules from the cavity and the hydration spheres of the interacting

  17. SPECTROSCOPIC PROPERTIES OF THE Ln-Ge COMPLEXES WITH DIETHYLENETRIAMINEPENTAACETIC ACID

    Directory of Open Access Journals (Sweden)

    Sergiy Smola

    2007-06-01

    Full Text Available Four new heteronuclear lanthanide complexes with general formula [Ge(OH(μ-HDTPALnGe(OH (μ-DTPA] (Ln = Sm – Dy were synthesized and subsequently characterized by different physico- chemical methods. The structures of new compounds have been proposed. In considered complexes the 4f-luminescence of three-charged ions of samarium, europium, terbium and dysprosium is realized at UV-excitation. It is noteworthy that it is the first observation of 4f-luminescence in water solutions of heteronuclear f-p-complexes. The comparison of luminescent characteristics of hetero- and homonuclear landthanide complexes is described and discussed as well.

  18. ATR-FTIR and UV-Vis Spectroscopic Studies of Aqueous U(IV)-oxalate Complexes under Mild Acidic Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Wansik; Jung, Euo Chang; Cho, Hyeryun; Park, Yangsoon; Ha, Yeongkeong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    The redox transformation process between U(VI) and U(IV) likely involves the participation of soluble or dissolved U(IV) species, such as U(IV)-hydroxo compounds and organic/inorganic ligand complexes. However, their role in the redox process has not been well documented, partly due to the ready oxidation of soluble U(IV) species, and partly due to the assumption that soluble or dissolved forms of U(IV) account for only a minor fraction of uranium in groundwater systems. In this study, a bidentate chelate ligand, oxalate (Ox) was selected to examine the complexation behaviors of U(IV) and ultimately its impact on the U(IV) solubility in mildly acidic solutions. Although some early studies reported that oxalate and pyrophosphate, i. e., multivalent anions, can form soluble U(IV) complexes, the related thermodynamic data and evidences for chemical speciation are very scarce. In our previous work, the U(IV)-Ox 1:1 complex was identified by monitoring the gradual transition of the characteristic absorption spectrum of U(OH){sup 3+} to that of UOx{sup 2+} upon the addition of oxalate at pH 1.6.2.0. This work aims to further provide spectroscopic evidence for the formation of multi-ligand complexes, i. e., U(Ox)n{sup 4-2n} (n ≥ 2) at pH 2-5 using attenuated total reflectance (ATR)- FTIR spectroscopy and UV-Vis absorption spectroscopy. The solid phase of U(IV)-Ox complex system was also characterized through an XRD analysis. Analysis of the FTIR spectra is found to be useful to determine the complexation stoichiometry and to obtain the structural information of the complexes. The outcome of the spectroscopic analysis for the multi-ligand complexation equilibria will be discussed in detail.

  19. Synthesis, characterization, and biological properties of nano-rare earth complexes with L-glutamic acid and imidazole

    Institute of Scientific and Technical Information of China (English)

    ZHOU Meifeng; HE Qizhuang

    2008-01-01

    Four nano-rare earth ternary complexes of L-glutamic acid and imidazole RE(Glu)3ImCl3·3H2O (RE=Ce3+, Pr3+, Sm3+, Dy3+, Glu= L-glutamic acid , and Im=imidazole) were synthesized. Their composition was characterized with elemental analysis, IR, and molar conductance. The TEM image indicated that the complexes were regular shaped and the length was about 30~60 nm. The antibacterial activity test showed that all these complexes exhibited better antibacterial ability against Escherichia coli, Staphylociccus aureus, and Candida albican (MIC were about 180, 100, and 310 μg/ml, respectively) and could be considered as broad-spectral antimicrobial. Their antitumor activity in vitro against leukemia K562 cells was measured using the MTT method. The results indicate that the four complexes possess strong inhibition effect on leukemia K562 cells. An approximately linear relationship is discovered between the relative inhibition rate and concentration, with the correlation coefficients R>0.7 and P<0.05, which is considered statistically significant.

  20. The structure of the complex between avidin and the dye, 2-(4'-hydroxyazobenzene) benzoic acid (HABA).

    Science.gov (United States)

    Livnah, O; Bayer, E A; Wilchek, M; Sussman, J L

    1993-08-09

    The crystal structure of the complex formed between the egg-white biotin-binding protein, avidin, and the dye, 2-(4'-hydroxyazobenzene) benzoic acid (HABA), was determined to a resolution of 2.5 A. The interaction of avidin with the benzoate ring of HABA is essentially identical to that of the complex formed between HABA and streptavidin (the bacterial analogue of the egg-white protein). This interaction emulates the definitive high-affinity interaction of both proteins with the ureido moiety of biotin. The major difference between the avidin- and streptavidin-HABA complexes lies in their interaction with the hydroxyphenyl ring of the dye molecule; in avidin, two adjacent amino acid residues (Phe72 and Ser73), which are not present in streptavidin, form additional interactions with this ring. These are suggested to account for the higher affinity of avidin for HABA. The characteristic red shift, which accompanies the interaction of both proteins with the dye, was traced to a proposed charge-transfer complex formed between the hydroxyphenyl ring of HABA and the indole ring of Trp70 in avidin (Trp79 in streptavidin). Comparison of binding site residues of two such similar proteins versus their markedly different affinities for two such different substrates should eventually contribute to a better design of biomimetic reagents and drugs.

  1. Complexation of Cu(II) by original tartaric acid-based ligands in nonionic micellar media: thermodynamic study and applications.

    Science.gov (United States)

    Dupont-Leclercq, Laurence; Giroux, Sébastien; Parant, Stéphane; Khoudour, Leïla; Henry, Bernard; Rubini, Patrice

    2009-04-09

    The complexation of Cu(II) with original alkylamidotartaric acids (C(x)T) is investigated in homogeneous aqueous medium and in the presence of nonionic micelles of Brij 58 (C16EO20), thanks to various analytical techniques such as NMR self-diffusion experiments, CD and UV-vis spectroscopy, ESI mass spectrometry, pHmetry and micellar-enhanced ultrafiltration (MEUF). First, a complete speciation study proves the formation of dimeric complexes in water and provides their formation constants. Second, a similar study is led in the presence of nonionic micelles. It underlines a modification of the apparent equilibrium constants in micellar medium and demonstrates that the structure of the complexes is slightly modified in the presence of micelles. This thermodynamic and structural study is applied to modelize the evolution of the extraction yields of Cu(II) by the micelles as a function of pH and to identify the complexes extracted in the micelles. The effects of the chain length of the ligand (C3T vs C8T) on the solubilization properties are put into relief and discussed. Anionic species are proved to be more incorporated in the nonionic micelles than the cationic species. The extracting system constituted of octylamidotartaric acid (CsT) solubilized in nonionic micelles of Brij 58 is demonstrated to be very efficient for the extraction of Cu(II) by MEUF, this technique being an interesting green alternative to traditional solvent extraction.

  2. Mixed ligand complexes of essential metal ions with L-glutamine and succinic acid in SLS-water mixtures

    Directory of Open Access Journals (Sweden)

    Bindu Hima Gandham

    2012-01-01

    Full Text Available Speciation of mixed ligand complexes of Co(II, Ni(II and Cu(II with L-glutamine and succinic acid was studied in varying amounts (0.0-2.5% w/v of sodium lauryl sulphate in aqueous solutions maintaining an ionic strength of 0.16 mol L-1 (NaCl at 303.0 K. Titrations were carried out in the presence of different relative concentrations (M : L : X = 1 : 2 : 2, 1 : 4 : 2, 1 : 2 : 4 of metal (M to L-glutamine (L to succinic acid (X with sodium hydroxide. Stability constants of ternary complexes were refined with MINIQUAD75. The best-fit chemical models were selected based on statistical parameters and residual analysis. The species detected were ML2X, MLX, MLXH and MLXH2 for Co(II, Ni(II and Cu(II. Extra stability of ternary complexes compared to their binary complexes was believed to be due to electrostatic interactions of the side chains of ligands, charge neutralization, chelate effect, stacking interactions and hydrogen bonding. The species distribution with pH at different compositions of SLS and plausible equilibria for the formation of species were also presented.

  3. Synthesis and Crystal Structure of Palladium(Ⅱ) Complex with 2,2'-Bipyridine-3,3'-dicarboxylic Acid

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The title complex Pd(H2BDA)Cl2(2DMSO (C16H14Cl2N2O6PdS2, H2BDA = 2,2'- bipyridine-3,3'-dicarboxylic acid) has been synthesized and characterized by IR spectra, elemental analysis and 1H NMR spectra. Its structure was determined by single-crystal X-ray diffraction analysis. The complex crystallizes in the monoclinic system, space group P21/c with a = 1.3604(6), b = 1.2606(6), c = 1.3521(6) nm, β = 103.677(7)°, V = 2.2530(17) nm3, Mr = 571.75, Z = 4, Dc = 1.686 g/cm3, μ = 1.280 mm-1, F(000) = 1136, R = 0.0405 and wR = 0.0908. The complex presents a planar quadrangle arrangement and is assembled via hydrogen bonds.

  4. Novel metal complexes of mixed piperaquine-acetaminophen and piperaquine-acetylsalicylic acid: Synthesis, characterization and antimicrobial activities

    Directory of Open Access Journals (Sweden)

    Yusuf Oloruntoyin Ayipo

    2016-11-01

    Full Text Available Synthesis of coordination compounds of Zinc(II, Copper(II, Nickel(II, Cobalt(II and Iron(II with mixed piperaquine-acetaminophen and piperaquine-acetylsalicylic acid has been studied. The complexes were characterized via: solubility test, melting point determination, conductivity measurement, Atomic Absorption Spectroscopy, UV-Visible Spectroscopy, FTIR Spectroscopy and magnetic susceptibility. The complexes were proposed to have a stoichiometry ratio of 1:1:1 between each metal salt and the ligands with tetrahedral and octahedral geometry following the reaction pattern of MX.yH2O + L1L2/3 to give ML1L2/3X.yH2O. Biological activities of the synthesized complexes have been evaluated against Escherichia coli and Staphylococcus aureus.

  5. Synthesis, characterization of the luminescent lanthanide complexes with ( Z)-4-(4-methoxyphenoxy)-4-oxobut-2-enoic acid

    Science.gov (United States)

    Duan, Guo-Jian; Yang, Ying; Liu, Tong-Huan; Gao, Ya-Ping

    2008-02-01

    ( Z)-4-(4-Methoxyphenoxy)-4-oxobut-2-enoic acid and its solid rare earth complexes LnL 3·2H 2O (Ln = La, Eu, Tb) were synthesized and characterized by means of MS, elemental analysis, FTIR, 13C NMR and TG-DTA. The IR and 13C NMR results show that the carboxylic groups in the complexes coordinated to the rare earth ions in the form of a bidentate ligand, but the ester carboxylic groups have not taken part in the coordination. The luminescence spectra of Eu(III) and Tb(III) complexes in solid state were also studied. The strong luminescence emitting peaks at 616 nm for Eu(III) and 547 nm for Tb(III) can be observed, which could be attributed to the ligand has an enhanced effect to the luminescence intensity of the Eu and Tb.

  6. The study on the interaction between Tb(III) and ligand in Tb-acetylsalicylic acid complex and fluorescence mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Wu Wenru; Rong Yuzhi; Zhao Bo [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Environmental Science, Nanjing Normal University, Nanjing, 210097 (China); Sun Peipei, E-mail: sunpeipei@njnu.edu.c [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Environmental Science, Nanjing Normal University, Nanjing, 210097 (China); Huang Xiaohua, E-mail: huangxiaohua@njnu.edu.c [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Environmental Science, Nanjing Normal University, Nanjing, 210097 (China)

    2010-01-15

    In this paper, a luminescent complex of terbium-acetylsalicylic acid (Tb-ASA) was studied for the first time using combination of the quantum chemical calculation, fluorescence spectroscopic method and X-ray photoelectron spectroscopy (XPS). The results from the quantum chemical calculation indicated that it is possible for the energy-transfer from ASA to Tb (III); Fluorescence spectroscopy demonstrated that there is an intramolecular energy-transfer from ASA to Tb with the efficiency (III) of about 87.9% under an excitation at 308 nm. The XPS indicated that the coordinate covalent bond between Tb and O existed in the complex of Tb-ASA leads to the effective energy transfer from ASA to Tb (III) because the energy transfer rate may be improved with reducing the distance between the ligand and Tb (III). The results will have important values for the studies of this type of complexes.

  7. Improvement in fingerprint detection using Tb(III)-dipicolinic acid complex doped nanobeads and time resolved imaging.

    Science.gov (United States)

    Hauser, Frank M; Knupp, Gerd; Officer, Simon

    2015-08-01

    This paper deals with the synthesis and application of lanthanide complex doped nanobeads used as a luminescent fingerprint powder. Due to their special optical properties, namely a long emission lifetime, sharp emission profiles and large Stokes shifts, luminescent lanthanide complexes are useful for discriminating against signals from background emissions. This is a big advantage because latent fingerprints placed on multicoloured fluorescent surfaces are difficult to develop with conventional powders. The complex of 2,6-dipicolinic acid (DPA) and terbium ([Tb(DPA)3](3-)) is used for this purpose. Using the Stöber process, this complex is incorporated into a silica matrix forming nanosized beads (230-630nm). It is shown that the [Tb(DPA)3](3-) is successfully incorporated into the beads and that these beads exhibit the wanted optical properties of the complex. A phenyl functionalisation is applied to increase the lipophilicity of the beads and finally the beads are used to develop latent fingerprints. A device for time resolved imaging was built to improve the contrast between developed fingerprint and different background signals, whilst still detecting the long lasting luminescence of the complex. The developed fingerprint powder is therefore promising to develop fingerprints on multicoloured fluorescent surfaces.

  8. Spectral and molecular modeling investigations of supramolecular complexes of mefenamic acid and aceclofenac with α- and β-cyclodextrin

    Science.gov (United States)

    Siva, S.; Kothai Nayaki, S.; Rajendiran, N.

    2017-03-01

    Inclusion complexes of mefenamic acid (MFA) and aceclofenac (ALF) with α- and β-cyclodextrins (CDs) in aqueous medium were investigated by absorption, fluorescence, time-resolved fluorescence methods. The solid inclusion complexes between drugs and CDs were characterized by SEM, TEM, FT-IR, 1H NMR, DSC and powder XRD techniques. Spectral studies indicated that both CDs form 1:1 inclusion complex with MFA and ALF. The experimental results revealed that the inclusion process is a spontaneous process. Time-resolved fluorescence studies suggested that ALF exhibited biexponential decay in aqueous and triexponential decay in CD whereas significant enhancement of lifetime of decay components of MFA was observed. Morphologies of drug-CD complexes observed by TEM demonstrate that self-aggregates of MFA/α-CD, ALF/α-CD and ALF/β-CD were nano-sized particles while vesicles were observed for MFA/β-CD. A spatial arrangement of inclusion complex is proposed based on 1H NMR and PM3 results. Investigations of thermodynamic and electronic properties confirmed the stability of the inclusion complex.

  9. A STUDY OF THE GALLIC ACID COMPLEXES OF NIOBIUM, TANTALUM, TITANIUM, AND IRON,

    Science.gov (United States)

    The use of gallic acid in a spectrophotometric procecure for tantalum, niobium and other metals was investigated. The optical properties of Nb, Ta and several other metal chelates were explored. (Author)

  10. The complex and important cellular and metabolic functions of saturated fatty acids

    OpenAIRE

    Legrand, Philippe; Rioux, Vincent

    2010-01-01

    This review summarizes recent findings on the metabolism and biological functions of saturated fatty acids (SFA). Some of these findings show that SFA may have important and specific roles in the cells. Elucidated biochemical mechanisms like protein acylation (N-myristoylation, S-palmitoylation) and regulation of gene transcription are presented. In terms of physiology, SFA are involved for instance in lipogenesis, fat deposition, polyunsaturated fatty acids bioavailability and apoptosis. The...

  11. Kinetics and Mechanism for Formation of Olefin Complexes in the Reaction between Palladium(II) and Maleic Acid.

    Science.gov (United States)

    Shi, Tiesheng; Elding, Lars I.

    1998-10-19

    Complex formation between Pd(H(2)O)(4)(2+) and maleic acid (H(2)A) has been studied at 25 degrees C and 2.00 M ionic strength in acidic aqueous solution. Reaction takes place with 1:1 stoichiometry. The kinetics has been followed by use of stopped-flow spectrophotometry under pseudo-first-order conditions with maleic acid in excess. In the concentration ranges 0.01 C where, in addition, both steps contain contributions from parallel reactions. The amplitude of the first phase increases with increasing [H(2)A](tot) and with decreasing [H(+)]. Multiwavelength global analysis of the kinetic traces and the UV-vis spectral changes suggest that a monodentate oxygen-bonded hydrogen maleate complex, [Pd(H(2)O)(3)OOCCH=CHCOOH](+), B, with stability constant K(2) = 205 +/- 40 M(-)(1) is formed as an intermediate in this first step via two parallel reversible reactions in which Pd(H(2)O)(4)(2+) reacts with maleic acid and hydrogen maleate, respectively. In the following step, B --> C, slow intramolecular ring closure with a rate constant of 0.8 +/- 0.1 s(-)(1) at 25 degrees C gives the reaction product C, which is concluded to be a 4.5-membered olefin-carboxylato chelate complex on the basis of stoichiometry and UV-vis/NMR spectra. Parallel and irreversible attack by maleic acid and hydrogen maleate acting as olefins on the intermediate B also leads to formation of C. C is stable for at least 20 h for concentrations of acid. Neither a steady-state approximation nor a rapid preequilibrium assumption can be used for the kinetics data treatment. Exact rate expressions for the fast and slow phases have been used to derive all rate constants involved. Olefins are inefficient nucleophiles toward palladium(II), even less efficient than carboxylic acids and carboxylates.

  12. Classification of pseudo pairs between nucleotide bases and amino acids by analysis of nucleotide–protein complexes

    Science.gov (United States)

    Kondo, Jiro; Westhof, Eric

    2011-01-01

    Nucleotide bases are recognized by amino acid residues in a variety of DNA/RNA binding and nucleotide binding proteins. In this study, a total of 446 crystal structures of nucleotide–protein complexes are analyzed manually and pseudo pairs together with single and bifurcated hydrogen bonds observed between bases and amino acids are classified and annotated. Only 5 of the 20 usual amino acid residues, Asn, Gln, Asp, Glu and Arg, are able to orient in a coplanar fashion in order to form pseudo pairs with nucleotide bases through two hydrogen bonds. The peptide backbone can also form pseudo pairs with nucleotide bases and presents a strong bias for binding to the adenine base. The Watson–Crick side of the nucleotide bases is the major interaction edge participating in such pseudo pairs. Pseudo pairs between the Watson–Crick edge of guanine and Asp are frequently observed. The Hoogsteen edge of the purine bases is a good discriminatory element in recognition of nucleotide bases by protein side chains through the pseudo pairing: the Hoogsteen edge of adenine is recognized by various amino acids while the Hoogsteen edge of guanine is only recognized by Arg. The sugar edge is rarely recognized by either the side-chain or peptide backbone of amino acid residues. PMID:21737431

  13. Classification of pseudo pairs between nucleotide bases and amino acids by analysis of nucleotide-protein complexes.

    Science.gov (United States)

    Kondo, Jiro; Westhof, Eric

    2011-10-01

    Nucleotide bases are recognized by amino acid residues in a variety of DNA/RNA binding and nucleotide binding proteins. In this study, a total of 446 crystal structures of nucleotide-protein complexes are analyzed manually and pseudo pairs together with single and bifurcated hydrogen bonds observed between bases and amino acids are classified and annotated. Only 5 of the 20 usual amino acid residues, Asn, Gln, Asp, Glu and Arg, are able to orient in a coplanar fashion in order to form pseudo pairs with nucleotide bases through two hydrogen bonds. The peptide backbone can also form pseudo pairs with nucleotide bases and presents a strong bias for binding to the adenine base. The Watson-Crick side of the nucleotide bases is the major interaction edge participating in such pseudo pairs. Pseudo pairs between the Watson-Crick edge of guanine and Asp are frequently observed. The Hoogsteen edge of the purine bases is a good discriminatory element in recognition of nucleotide bases by protein side chains through the pseudo pairing: the Hoogsteen edge of adenine is recognized by various amino acids while the Hoogsteen edge of guanine is only recognized by Arg. The sugar edge is rarely recognized by either the side-chain or peptide backbone of amino acid residues.

  14. Understanding Pathway Complexity of Organic Micro/Nanofiber Growth in Hydrogen Bonded Co-Assembly of Aromatic Amino Acids.

    Science.gov (United States)

    Xing, Pengyao; Li, Peizhou; Chen, Hongzhong; Hao, Aiyou; Zhao, Yanli

    2017-04-03

    Rational engineering of one-dimensional (1D) self-assembled aggregates to produce desired materials for versatile functions remains a challenge. In this work, we report the noncovalent modulation of 1D aggregates at micro/nanoscale using a co-assembly protocol. Aromatic amino acids were employed as the model building blocks, and melamine (Mm) behaves as a modulator to form co-assembly arrays with aromatic amino acids selectively. The selective self-assembly behavior between aromatic amino acids and Mm allows distinguishing and detecting Mm and aromatic amino acids from their analogues in macroscopic and microscopic scales. Dimensions and sizes of fibrous aggregates prepared from different amino acids show two opposite pathways from pristine assemblies to co-assemblies induced by the addition of Mm. This pathway complexity could be controlled by the molecular conformation determined by α-positioned substituents. The developed hypothesis presents an excellent expansibility to other substrates, which may guide us to rationally design and screen 1D materials with different dimensions and sizes including the production of high-quality self-standing hydrogels.

  15. Main Group Lewis Acid-Mediated Transformations of Transition-Metal Hydride Complexes.

    Science.gov (United States)

    Maity, Ayan; Teets, Thomas S

    2016-08-10

    This Review highlights stoichiometric reactions and elementary steps of catalytic reactions involving cooperative participation of transition-metal hydrides and main group Lewis acids. Included are reactions where the transition-metal hydride acts as a reactant as well as transformations that form the metal hydride as a product. This Review is divided by reaction type, illustrating the diverse roles that Lewis acids can play in mediating transformations involving transition-metal hydrides as either reactants or products. We begin with a discussion of reactions where metal hydrides form direct adducts with Lewis acids, elaborating the structure and dynamics of the products of these reactions. The bulk of this Review focuses on reactions where the transition metal and Lewis acid act in cooperation, and includes sections on carbonyl reduction, H2 activation, and hydride elimination reactions, all of which can be promoted by Lewis acids. Also included is a section on Lewis acid-base secondary coordination sphere interactions, which can influence the reactivity of hydrides. Work from the past 50 years is included, but the majority of this Review focuses on research from the past decade, with the intent of showcasing the rapid emergence of this field and the potential for further development into the future.

  16. Formation Equilibria of Ternary Metal Complexes with Citric Acid and Glutamine (Alanine) in Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    王进平; 牛春吉; 杨魁跃; 倪嘉缵

    2004-01-01

    The species and their formation constants in the ternary systems were obtained by the Scogs2 software from potentiometric titration data. The Comics software was used to calculate the distribution of species in the ternary systems. MLXH, MLXH2 and MLXH3 are the common species in these systems. The coordination behaviors of the rare earths are very similar and their stability is closely matched. The ternary rare earth complexes are more stable than the corresponding ternary complexes of calcium. The ternary zinc complex with glutamine as the secondary ligand is more stable than the corresponding complexes of rare earths, but the ternary complex with alanine as the secondary ligand shows an inverse trend. The distributions of species in the ternary systems vary with pH changing. A prediction can be made that exogenous rare earths can affect the species of Ca and Zn in human body.

  17. Nucleic acid interaction and antibacterial behaviours of a ternary palladium(II) complexes

    Science.gov (United States)

    Patel, Mohan N.; Dosi, Promise A.; Bhatt, Bhupesh S.

    2012-02-01

    The bidentate ligands and Pd(II) complexes have been synthesized and characterized using elemental analysis (C, H, N), 1H NMR, 13C NMR, electronic spectra, FT-IR and FAB mass spectroscopy. The binding of palladium complexes with calf thymus DNA (CT DNA) has been explored using absorption titration, DNA melting temperature and viscosity measurements. The cleavage reaction on pUC19 DNA has been monitored by agarose gel electrophoresis. The results suggest that complexes can bind to DNA by intercalative modes and exhibit nuclease activities in which supercoil form is converted to open circular form. The antibacterial activity of ligands and complexes has been performed against three Gram(-ve) and two Gram(+ve) microorganisms and the study indicates that all the complexes show better microbial inhibition activity than ligands and palladium salt.

  18. Propriedades ácido-base e de complexação de ácidos húmico e fúlvico isolados de vermicomposto Acid/base and complexation properties of humic and fulvic acids isolated from vermicompost

    Directory of Open Access Journals (Sweden)

    Sandro de Miranda Colombo

    2007-10-01

    Full Text Available Proton binding properties of humic and fulvic acids were studied by potentiometric titration. Carboxylic groups were the predominant ionizable sites in comparison to phenolic and amine groups. Total acidity of fulvic acid was 12 x 10-3 mol g-1, a number significantly higher than that obtained for humic acid (5.2 x 10-3 mol g-1. Copper ion binding was evaluated at pH 4, 5 and 6 by potentiometric titration with an ion selective electrode for Cu(II. Differential stability constants and complexation capacities were systematically higher for humic acid, despite its lower number of ionizable sites in comparison with fulvic acid.

  19. Air-stable platinum and palladium complexes featuring bis[2,4-bis(trifluoromethyl)phenyl]phosphinous acid ligands.

    Science.gov (United States)

    Kurscheid, Boris; Neumann, Beate; Stammler, Hans-Georg; Hoge, Berthold

    2011-12-23

    Secondary phosphane oxides, R(2)P(O)H, are commonly used as preligands for transition-metal complexes of phosphinous acids, R(2)P-OH (R=alkyl, aryl), which are relevant as efficient catalysts in cross-coupling processes. In contrast to previous work by other groups, we are interested in the ligating properties of an electron-deficient phosphinous acid, (R(f))(2)P-OH, bearing the strongly electron-withdrawing and sterically demanding 2,4-bis(trifluoromethyl)phenyl group towards catalysis-relevant metals, such as palladium and platinum. The preligand bis[2,4-bis(trifluoromethyl)phenyl]phosphane oxide, (R(f))(2)P(O)H, reacts smoothly with solid platinum(II) dichloride yielding the trans-configured phosphinous acid platinum complex trans-[PtCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)POH)(2)]. The deprotonation of one phosphinous acid ligand with an appropriate base leads to the cis-configured monoanion complex cis-[PtCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)H](-), featuring the quasi-chelating phosphinous acid phosphinito unit, (R(f))(2)P-O-H···O=P(R(f))(2), which exhibits a strong hydrogen bridge substantiated by an O···O distance of 245.1(4) pm. The second deprotonation step is accompanied by a rearrangement to afford the trans-configured dianion trans-[PtCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)](2-). The reaction of (R(f))(2)P(O)H with solid palladium(II) dichloride initially yields a mononuclear palladium complex [PdCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)POH)(2)], which condenses under liberation of HCl to the neutral dinuclear palladium complex [Pd(2)(μ-Cl)(2){({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)H}(2)]. The equilibrium between the mononuclear [PdCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)POH)(2)] and dinuclear [Pd(2)(μ-Cl)(2){({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)H}(2)] palladium complexes is reversible and can be shifted in each direction by the addition of base or HCl, respectively. Treatment of palladium(II) hexafluoroacetylacetonate, [Pd(F(6)acac)(2)], with a slight excess of (R(f))(2)P

  20. Reactivity of pi-complexes of Ti, V, and Nb towards dithioacetic acid: Synthesis and structure of novel metal sulfur-containing complexes

    Science.gov (United States)

    Duraj, Stan A.; Andras, Maria T.; Hepp, Aloysius F.

    1990-01-01

    In order to use sulfur-containing resources economically and with minimal environmental damage, it is important to understand the desulfurization processes. Hydrodesulfurization, for example, is carried out on the surface of a heterogeneous metal sulfide catalyst. Studies of simple, soluble inorganic systems provide information regarding the structure and reactivity of sulfur-containing compounds with metal complexes. Further, consistent with recent trends in materials chemistry, many model compounds warrant further study as catalyst precursors. The reactivity of low-valent organometallic sandwich pi-complexes toward dithiocarboxylic acids is described. For example, treatment of bisbenzene vanadium with CH3CSSH affords a divanadium tetrakis(dithioacetate) complex. The crystallographically determined V-V bond distance, 2.800(2), is nearly the same as the V-V bond distance in a V(mu-nu squared-S2)2V' unit in the mineral patonite (VS4)n. The stability of the V2S4 core in the dimer is demonstrated by evidence of V2S4(+) in the mass spectrum (70 eV, solid probe) of the vanadium dimer. Several other systems relevant to HDS catalysis are also discussed.

  1. Potentiometric and spectral studies of complex formation of La(III), Pr(III) and Lu(III) with aspartic acid and asparagine

    Energy Technology Data Exchange (ETDEWEB)

    Wojciechowska, A.; Lomozik, L.; Zielinski, S.

    1987-12-01

    The composition and stability of La/sup 3 +/, Pr/sup 3 +/ and Lu/sup 3 +/ complexes with aspartic acid and asparagine were analysed. The formation of complexes of the type ML and MHL was determined for La/sup 3 +/ and Pr/sup 3 +/ with aspartic acid, and of the type MHL for Lu/sup 3 +/ with aspartic acid. For La/sup 3 +/, Pr/sup 3 +/ and Lu/sup 3 +/ with asparagine the formation of ML(OH) complexes was observed. By means of /sup 1/H NMR and /sup 13/C NMR studies the participation in the coordination of both -COOH groups was determined for aspartic acid, whereas for asparagine the participation of the -COOH group was determined in complexes with La/sup 3 +/, Pr/sup 3 +/, and of the -COOH and the -NH/sub 2/ groups in the complex with Lu/sup 3 +/.

  2. In vivo biocompatibility of new nano-calcium-deficient hydroxyapatite/poly-amino acid complex biomaterials

    Directory of Open Access Journals (Sweden)

    Dai ZY

    2015-10-01

    Full Text Available Zhenyu Dai,1,2,* Yue Li,3,* Weizhong Lu,2,* Dianming Jiang,4 Hong Li,1 Yonggang Yan,1 Guoyu Lv,1 Aiping Yang1 1College of Physical Science and Technology, Sichuan University, Chengdu, 2Department of Orthopedics, Chongqing Hospital of Traditional Chinese Medicine, 3Department of Clinical Laboratory, the Second Affiliated Hospital, 4Department of Orthopedics, the First Affiliated Hospital, Chongqing Medical University, Chongqing, People’s Republic of China *These authors contributed equally to this work Objective: To evaluate the compatibility of novel nano-calcium-deficient hydroxyapatite/poly-amino acid (n-CDHA/PAA complex biomaterials with muscle and bone tissue in an in vivo model.Methods: Thirty-two New Zealand white rabbits were used in this study. Biomaterials were surgically implanted into each rabbit in the back erector spinae and in tibia with induced defect. Polyethylene was implanted into rabbits in the control group and n-CDHA/PAA into those of the experimental group. Animals were examined at four different points in time: 2 weeks, 4 weeks, 12 weeks, and 24 weeks after surgery. They were euthanized after embolization. Back erector spinae muscles with the surgical implants were examined after hematoxylin and eosin (HE staining at these points in time. Tibia bones with the surgical implants were examined by X-ray and scanning electron microscopy (SEM at these points in time to evaluate the interface of the bone with the implanted biomaterials. Bone tissues were sectioned and subjected to HE, Masson, and toluidine blue staining.Results: HE staining of back erector spinae muscles at 4 weeks, 12 weeks, and 24 weeks after implantation of either n-CDHA/PAA or polyethylene showed disappearance of inflammation and normal arrangement in the peripheral tissue of implant biomaterials; no abnormal staining was observed. At 2 weeks after implantation, X-ray imaging of bone tissue samples in both experimental and control groups showed that

  3. Structural, spectroscopic and theoretical studies on 3,4,7,8-tetramethyl-1,10-phenantroline complex with picric acid

    Energy Technology Data Exchange (ETDEWEB)

    Bator, G., E-mail: gb@wchuwr.chem.uni.wroc.pl [Faculty of Chemistry, University of Wroclaw, Joliot - Curie 14, 50-383 Wroclaw (Poland); Sobczyk, L.; Sawka-Dobrowolska, W. [Faculty of Chemistry, University of Wroclaw, Joliot - Curie 14, 50-383 Wroclaw (Poland); Wuttke, J. [Forschungszentrum Juelich GmbH, Juelich Centre for Neutron Science, Outstation at FRM II, Lichtenbergstr. 1, 85747 Garching (Germany); Pawlukojc, A. [Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warszawa (Poland); Laboratory of Neutron Physics, Joint Institute for Nuclear Research, 141-980 Dubna (Russian Federation); Grech, E.; Nowicka-Scheibe, J. [Department of Inorganic and Analytical Chemistry, West Pomeranian University of Technology, Szczecin, Al. Piastow 42, 71-065 Szczecin (Poland)

    2013-01-02

    Highlights: Black-Right-Pointing-Pointer We synthesized a novel complex of Me{sub 4}phen Dot-Operator PA. Black-Right-Pointing-Pointer The complex was studied using infrared spectroscopy and inelastic neutron scattering. Black-Right-Pointing-Pointer The crystal structures at 100 K of pure Me{sub 4}phen and Me{sub 4}phen Dot-Operator PA was described. Black-Right-Pointing-Pointer The molecular structure in the crystalline state was theoretically calculated. -- Abstract: The almost planar molecular complex, formed by 3,4,7,8-tetramethyl-phenantroline (Me{sub 4}phen) and picric acid (2,4,6-trinitrophenol, PA), has been investigated by using X-ray diffraction, vibrational spectroscopy, tunnel splitting and theoretical analysis. In the crystal of Me{sub 4}phen{center_dot}PA two short bifurcated hydrogen bonds N{sup +}-H{center_dot}{center_dot}{center_dot}O{sup -} [2.6238(14) Angstrom-Sign ] and N{sup +}-H{center_dot}{center_dot}{center_dot}N [2.6898(15) Angstrom-Sign ] are created. Infra-red spectra show the hydrogen bonds are short. The neutron backscattering spectrum of Me{sub 4}phen Dot-Operator PA at 3 K shows two tunneling peaks at ca. 1 and 3 {mu}eV. The number of the peaks is consistent with X-ray diffraction studies, which disclosed the inequivalence of methyl groups in the crystal structure. The comparison of the tunnel splitting for neat Me{sub 4}phen and for its complex with picric acid indicates that in the latter case the methyl groups are more strongly engaged in the intermolecular interactions, particularly with nitro group oxygen atoms of picric acid, leading to an increase of the CH{sub 3} rotational barrier height.

  4. Synthesis, characterization, electrochemical studies and DFT calculations of amino acids ternary complexes of copper (II) with isonitrosoacetophenone. Biological activities

    Science.gov (United States)

    Tidjani-Rahmouni, Nabila; Bensiradj, Nour el Houda; Djebbar, Safia; Benali-Baitich, Ouassini

    2014-10-01

    Three mixed complexes having formula [Cu(INAP)L(H2O)2] where INAP = deprotonated isonitrosoacetophenone and L = deprotonated amino acid such as histidine, phenylalanine and tryptophan have been synthesized. They have also been characterized using elemental analyses, molar conductance, UV-Vis, IR and ESR spectra. The value of molar conductance indicates them to be non-electrolytes. The spectral studies support the binding of the ligands with two N and two O donor sites to the copper (II) ion, giving an arrangement of N2O2 donor groups. Density Functional Theory (DFT) calculations were applied to evaluate the cis and trans coordination modes of the two water molecules. The trans form was shown to be energetically more stable than the cis one. The ESR data indicate that the covalent character of the metal-ligand bonding in the copper (II) complexes increases on going from histidine to phenylalanine to tryptophan. The electrochemical behavior of the copper (II) complexes was determined by cyclic voltammetry which shows that the chelate structure and electron donating effects of the ligands substituent are among the factors influencing the redox potentials of the complexes. The antimicrobial activities of the complexes were evaluated against several pathogenic microorganisms to assess their antimicrobial potentials. The copper complexes were found to be more active against Gram-positive than Gram-negative bacteria. Furthermore, the antioxidant efficiencies of the metal complexes were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. The antioxidant activity of the complexes indicates their moderate scavenging activity against the radical DPPH.

  5. In Vivo Multienzyme Complex Coconstruction of N-Acetylneuraminic Acid Lyase and N-Acetylglucosamine-2-epimerase for Biosynthesis of N-Acetylneuraminic Acid.

    Science.gov (United States)

    Wang, Zhenfu; Zhuang, Wei; Cheng, Jian; Sun, Wujin; Wu, Jinglan; Chen, Yong; Ying, Hanjie

    2017-08-30

    Metabolic channeling enables efficient transfer of the intermediates by forming a multienzyme complex. To leverage the metabolic channeling for improved biosynthesis, we coexpressed N-acetylneuraminic acid lyase from C. glutamicum ATCC 13032 (CgNal) and N-acetylglucosamine-2-epimerase from Anabaena sp. CH1 (anAGE) in Escherichia coli and used the whole cell to synthesize N-acetylneuraminic acid (Neu5Ac) from N-acetylglucosamine (GlcNAc) and pyruvate. To get the multienzyme complex, polycistronic plasmid with high levels of CgNal and anAGE expression was constructed by tuning the orders of the genes. The Shine-Dalgarno (SD) sequence and aligned spacing (AS) distance were optimized. The E. coli Rosetta harboring the polycistronic plasmid pET-28a-SD2-AS1-CgNal-SD-AS-anAGE increased the production of Neu5Ac by 58.7% to 92.5 g/L in 36 h by whole-cell catalysis and by 21.9% up to 112.8 g/L in 24 h with the addition of Triton X-100.

  6. Hyaluronan/Tannic Acid Nanoparticles Via Catechol/Boronate Complexation as a Smart Antibacterial System.

    Science.gov (United States)

    Montanari, Elita; Gennari, Arianna; Pelliccia, Maria; Gourmel, Charlotte; Lallana, Enrique; Matricardi, Pietro; McBain, Andrew J; Tirelli, Nicola

    2016-12-01

    Nanoparticles based on hyaluronic acid (HA) are designed to deliver tannic acid (TA) as an antimicrobial agent. The presence of HA makes these particles potentially useful to target bacteria that colonize cells presenting HA membrane receptors (e.g. CD44), such as macrophages. HA bearing 3-aminophenyl boronic acid groups (HA-APBA) is reacted with TA, yielding nanoparticles with a size that decreases with decreasing HA molecular weight (e.g. 200 nm for 44 kDa, 400 nm for 737 kDa). The boronate esters make the nanoparticles stable at physiological pH, but their hydrolysis in an acidic environment (pH = 5) leads to swelling/solubilization, therefore potentially allowing TA release in endosomal compartments. We have assessed the nanoparticle toxicity profile (on RAW 264.7 macrophages) and their antimicrobial activity (on E. coli and on both methicillin-sensitive and -resistant S. aureus). The antibacterial effect of HA-APBA/TA nanoparticles was significantly higher than that of TA alone, and has very similar activity to TA coformulated with a reducing agent (ascorbic acid), which indicates both the nanoparticles to protect TA catechols from oxidation, and the effective release of TA after nanoparticle internalization. Therefore, there is potential for these nanoparticles to be used in stable, effective, and potentially targetable nanoparticle-based antimicrobial formulations.

  7. Selective removal of phosphate for analysis of organic acids in complex samples.

    Science.gov (United States)

    Deshmukh, Sandeep; Frolov, Andrej; Marcillo, Andrea; Birkemeyer, Claudia

    2015-04-03

    Accurate quantitation of compounds in samples of biological origin is often hampered by matrix interferences one of which occurs in GC-MS analysis from the presence of highly abundant phosphate. Consequently, high concentrations of phosphate need to be removed before sample analysis. Within this context, we screened 17 anion exchange solid-phase extraction (SPE) materials for selective phosphate removal using different protocols to meet the challenge of simultaneous recovery of six common organic acids in aqueous samples prior to derivatization for GC-MS analysis. Up to 75% recovery was achieved for the most organic acids, only the low pKa tartaric and citric acids were badly recovered. Compared to the traditional approach of phosphate removal by precipitation, SPE had a broader compatibility with common detection methods and performed more selectively among the organic acids under investigation. Based on the results of this study, it is recommended that phosphate removal strategies during the analysis of biologically relevant small molecular weight organic acids consider the respective pKa of the anticipated analytes and the detection method of choice. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Investigation of Complexation of Linear Poly(N-vinyl-2-pyrrolidone with Poly(methacrylic acid-co-methyl methacrylate Gel

    Directory of Open Access Journals (Sweden)

    Guoqin Liu

    2011-01-01

    Full Text Available The contraction of poly(methacrylic acid-co-methyl methacrylate (P(MAA-co-MMA gel induced by complexation with linear poly(N-vinyl-2-pyrrolidone (PVP is quite different from that of poly(acrylic acid (PAA or poly(methacrylic acid (PMAA gel. It was found that the concentration of PVP has a strong effect on the complexation with P(MAA-co-MMA gel. When PVP was introduced into the P(MAA-co-MMA network, its dynamic mechanic properties vary greatly between complexed and uncomplexed networks. It had the following results: (1 the higher modulus ratio; (2 a slight contraction of gel.

  9. Influences of size-fractionated humic acids on arsenite and arsenate complexation and toxicity to Daphnia magna.

    Science.gov (United States)

    Ren, Jinqian; Fan, Wenhong; Wang, Xiangrui; Ma, Qingquan; Li, Xiaomin; Xu, Zhizhen; Wei, Chaoyang

    2017-01-01

    The intrinsic physicochemical properties of dissolved organic matter (DOM) may affect the mobility and toxicity of arsenic in aquatic environments. In the present study, the humic acid (HA) was ultra-filtered into five fractions according to molecular weight, and their physicochemical properties were characterized. Complexation of HA fractions with arsenite and arsenate was first determined by differential pulse polarography (DPP). The influences of HA fractions on arsenic toxicity were then examined using Daphnia magna as a model organism. As(V) had a higher affinity with HA than As(III), and their complexation was dependent on the total acidity and fluorescence characteristics of DOM. We demonstrated that the acidity and fluorescence also better explained the As toxicity to daphnids than UV absorbance and hydraulic diameter. Arsenic speciation determined by DPP significantly affected the toxicity of arsenite and arsenate. The results extended the free-ion activity model application to the case of arsenic. The present study clearly indicated that DOM with different molecular weights has distinct physicochemical properties, and could influence the speciation and toxicity of As to different extent. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Crystal structures of Leishmania mexicana arginase complexed with α,α-disubstituted boronic amino-acid inhibitors.

    Science.gov (United States)

    Hai, Yang; Christianson, David W

    2016-04-01

    Leishmania arginase is a potential drug target for the treatment of leishmaniasis because this binuclear manganese metalloenzyme initiates de novo polyamine biosynthesis by catalyzing the hydrolysis of L-arginine to generate L-ornithine and urea. The product L-ornithine subsequently undergoes decarboxylation to yield putrescine, which in turn is utilized for spermidine biosynthesis. Polyamines such as spermidine are essential for the growth and survival of the parasite, so inhibition of enzymes in the polyamine-biosynthetic pathway comprises an effective strategy for treating parasitic infections. To this end, two X-ray crystal structures of L. mexicana arginase complexed with α,α-disubstituted boronic amino-acid inhibitors based on the molecular scaffold of 2-(S)-amino-6-boronohexanoic acid are now reported. Structural comparisons with human and parasitic arginase complexes reveal interesting differences in the binding modes of the additional α-substituents, i.e. the D side chains, of these inhibitors. Subtle differences in the three-dimensional contours of the outer active-site rims among arginases from different species lead to different conformations of the D side chains and thus different inhibitor-affinity trends. The structures suggest that it is possible to maintain affinity while fine-tuning intermolecular interactions of the D side chain of α,α-disubstituted boronic amino-acid inhibitors in the search for isozyme-specific and species-specific arginase inhibitors.

  11. Removal of fluoride ion from aqueous solution by a cerium-poly(hydroxamic acid) resin complex.

    Science.gov (United States)

    Haron, M J; Yunus, W M

    2001-05-01

    A cerium-loaded poly(hydroxamic acid) chelating ion exchanger was used for fluoride ion removal from aqueous solution. The resin was effective in decreasing the fluoride concentration from 5 mM down to 0.001 mM in acidic pH between 3 and 6. The sorption followed a Langmuir model with a maximum capacity of 0.5 mmol/g. The removal is accomplished by an anion exchange mechanism. The rate constant for the sorption was found to be 9.6 x 10(-2) min-1. A column test shows that the fluoride ion was retained on the column until breakthrough point and the fluoride sorbed in the column can be eluted with 0.1 M NaOH. The column can be reused after being condition with hydrochloric acid at pH 4. The resin was tested and found to be effective for removal of fluoride from actual industrial wastewater.

  12. [Mass spectrometry of triterpene glycosides molecular complexation with purine bases of nucleic acids].

    Science.gov (United States)

    Lekar', A V; Vetrova, E V; Borisenko, N I; Iakovishin, L A; Grishkovets, V I

    2011-01-01

    The molecular complexation of adenine and guanine with hederagenin 3-O-alpha-L-rhamnopyranosyl-(1-->2)-O-alpha-L-arabinopyranoside (alpha-hederin) and its 28-O-alpha-L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl-(1-->6)-O-beta-D-glucopyranosyl ester (hederasaponin C) was investigated for the first time using the method of electrospray ionization mass spectrometry. Guanine forms complexes more diverse in composition than adenine.

  13. Complexes of hydroxamates. V: Equilibrium and kinetics of the formation of the binary and ternary complexes involved in the nickel(II)-histidinehydroxamic acid-pyridoxal system.

    Science.gov (United States)

    el-Ezaby, M S; Shuaib, N M; Marafie, H M; Hassan, M M

    1988-07-01

    Equilibrium-based computer models utilizing SUPERQUAD program were made to determine the formation constants of the binary complexes of Ni(II) with histidine-hydroxamic acid (HX) from pH-metric titration data at 25 degrees C and I = 0.15 M NaCl. The species were monomeric in the pH range 3.0-8.0. The mechanism of their complex formation was determined using the stopped flow technique under the same experimental conditions of the equilibrium study. It has been concluded that Ni2+ and NiOH- were the active species in the complex formation reactions. Moreover, the reaction of HX with pyridoxal (PL) was studied in the absence of metal-ions by polarographic and spectrophotometric techniques at pH greater than or equal to 5.0. No rates were observed by using the stopped-flow methods. The formation constants for the binary system (HX-PL) and the ternary system (Ni(II)-HX-PL) were also determined by the same program applied on data obtained from pH metric titration at 25 degrees C and I = 0.15 M NaCl. Ternary complex formation involving PL and the species of the Ni(II)-HX system was also investigated kinetically in the pH range of 6.5-10.5. Several rate steps have been observed which have been interpreted qualitatively in terms of sequence of processes involving the condensation of aldehydic form of PL with amino moiety of HX. A comparison with other pertinent systems is also discussed.

  14. Diastereomeric complex of ( R/ S)-piperidine-3-carboxylic acid with (2 R,3 R)-tartaric acid: Structural, spectroscopic and computational studies

    Science.gov (United States)

    Bartoszak-Adamska, E.; Dega-Szafran, Z.; Jaskólski, M.; Szafran, M.

    2011-07-01

    2:2 Complex of ( R) and ( S)-piperidine-3-carboxylic acids (P3C) with (2 R,3 R) -tartaric acid (TA), 1, has been characterized by single-crystal X-ray analysis, FTIR and NMR spectroscopies, and by DFT calculations. The crystals of 1 are monoclinic, space group P2 1. The crystal structure is formed by two distinct P3CH +·TA - components, A and B, linked by an O-H⋯O hydrogen bond of 2.603(2) Å. The A and B components differ in the absolute configuration of the C(3) atom of P3CH +; ( S) in A and ( R) in B. The piperidinium-3-carboxylic acid and (2 R,3 R)-semi-tartrate anion moieties of the components A and B are linked by O-H⋯O hydrogen bonds of 2.517(1) and 2.535(1) Å, respectively. In A and B the piperidinium rings adopt the chair conformation with the carboxyl group in the equatorial position. The structures of the monomers of P3CH +·TA -, 3A and 3B, as well as of a dimer 2, have been optimized by the B3LYP/6-31G(d,p) approach. The chemical shift assignments were based on two-dimensional 1H- 1H and 1H- 13C experiments.

  15. Complexation of europium(III) with the zwitterionic form of amino acids studied with ultraviolet-visible and time-resolved laser-induced fluorescence spectroscopy.

    Science.gov (United States)

    Heller, Anne; Rönitz, Olivia; Barkleit, Astrid; Bernhard, Gert; Ackermann, Jörg-Uwe

    2010-08-01

    The complex formation of europium(III) with the zwitterionic form of amino acids (alanine, phenylalanine, and threonine) has been studied in aqueous solution. Measurements were performed at I = 0.1 M (NaCl/NaClO(4)), room temperature, and trace metal concentrations in the range of pH 2 to 8 using ultraviolet-visible (UV-Vis) and time-resolved laser-induced fluorescence spectroscopy (TRLFS). While complexation leads to a significant luminescence enhancement in the emission spectrum of the metal ion, absorption in the UV-Vis spectrum of the amino acid (AA) decreases. As zwitterionic species (AAH), all three ligands form weak complexes with 1:1 stoichiometry and a general formula of EuAAH(3+) with the metal. The complex stability constants were determined to be log K approximately 1 for all complexes, indicating the negligible contribution of the amino acid side chain to the complex formation reaction.

  16. The gas-phase hydrogen bond complexes between formic acid with hydroxyl radical: a theoretical study.

    Science.gov (United States)

    Torrent-Sucarrat, Miquel; Anglada, Josep M

    2004-02-20

    We report a theoretical study on seven radical hydrogen bond complexes between syn-HCOOH and OH and eight radical hydrogen bond complexes between anti-HCOOH and OH, that have been carried out by using the B3LYP, MP2, QCISD, and CCSD(T) theoretical approaches with the 6-311 + G(2df,2p) basis set. In all cases, the bonding features were analysed using the atoms in molecules (AIM) theory by Bader and the natural bond orbital (NBO) partition scheme by Weinhold et al. We have found twelve complexes having a single hydrogen bond and three complexes presenting a cyclic structure with multiple bonds, pointing out the existence of a cooperative effect. One of them presents a bound O...O interaction producing a stabilisation effect. The stability of these complexes has been calculated to be in the -0.81 and -5.96 kcal mol-1 range and their possible implication in the HCOOH plus OH reaction is also discussed. Finally, we also report the computed harmonic vibrational frequencies of the two O-H stretching modes and the HOC out-of-plane wagging mode, along with the frequency red-shifts originated by the complex formation and the corresponding computed intensity ratio relative to the monomers.

  17. Mixed ligand complex formation of FeIII with boric acid and typical N-donor multidentate ligands

    Indian Academy of Sciences (India)

    G N Mukherjee; Ansuman Das

    2002-06-01

    Equilibrium study of the mixed ligand complex formation of FeIII with boric acid in the absence and in the presence of 2,2'-bipyridine, 1,10-phenanthroline, diethylenetriamine and triethylenetetramine (L) in different molar ratios provides evidence of formation of Fe(OH)2+, Fe(OH)$^{+}_{2}$, Fe(L)3+, Fe(H2BO4), Fe(OH)(H2BO4)-, Fe(OH)2(H2BO4)2-, Fe(L)(H2BO4) and Fe2(L)2(BO4)+ complexes. Fe(L)$^{3+}_{2}$, Fe(L)2(H2BO4) and Fe2(L)4(BO4)+ complexes are also indicated with 2,2'-bipyridine and 1,10-phenanthroline. Complex formation equilibria and stability constants of the complexes at 25 ± 0 × 1° C in aqueous solution at a fixed ionic strength, = 0.1 mol -3 (NaNO3) have been determined by potentiometric method.

  18. The inclusion complex of rosmarinic acid into beta-cyclodextrin: A thermodynamic and structural analysis by NMR and capillary electrophoresis.

    Science.gov (United States)

    Aksamija, Amra; Polidori, Ange; Plasson, Raphaël; Dangles, Olivier; Tomao, Valérie

    2016-10-01

    This work focuses on the characterization of the rosmarinic acid (RA)-β-cyclodextrin (CD) complex in aqueous solution by (1)H NMR (1D- and 2D-ROESY), completed with studies by capillary electrophoresis (CE). From the (1)H NMR data, the stoichiometry of the complex was determined by a Job's plot and the binding constant was estimated from a linear regression (Scott's method). At pH 2.9, the results showed that RA binds CD with a 1:1 stoichiometry and a binding constant Kb of 445 (±53) M(-1) or 465 (±81) M(-1) depending on the CD protons (H-5 or H-3) selected for the evaluation. The Kb value was also calculated from the CD-induced chemical shifts of each RA proton in order to collect information on the structure of the complex. The pH dependence of Kb revealed that the RA carboxylic form displays the highest affinity for CD. An investigation by capillary electrophoresis fully confirmed these results. 2D ROESY analysis provided detailed structural information on the complex and showed a strong correlation between H-3 and H-5 of CD and most RA protons. In conclusion, RA, an efficient phenolic antioxidant from rosemary with a marketing authorization, spontaneously forms a relatively stable inclusion complex with CD in water.

  19. Complexation studies with lanthanides and humic acid analyzed by ultrafiltration and capillary electrophoresis-inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Kautenburger, Ralf; Beck, Horst Philipp

    2007-08-03

    For the long-term storage of radioactive waste, detailed information about geo-chemical behavior of radioactive and toxic metal ions under environmental conditions is necessary. Humic acid (HA) can play an important role in the immobilisation or mobilisation of metal ions due to complexation and colloid formation. Therefore, we investigate the complexation behavior of HA and its influence on the migration or retardation of selected lanthanides (europium and gadolinium as homologues of the actinides americium and curium). Two independent speciation techniques, ultrafiltration and capillary electrophoresis coupled with inductively coupled plasma mass spectrometry (CE-ICP-MS) have been compared for the study of Eu and Gd interaction with (purified Aldrich) HA. The degree of complexation of Eu and Gd in 25 mg l(-1) Aldrich HA solutions was determined with a broad range of metal loading (Eu and Gd total concentration between 10(-6) and 10(-4) mol l(-1)), ionic strength of 10 mM (NaClO4) and different pH-values. From the CE-ICP-MS electropherograms, additional information on the charge of the Eu species was obtained by the use of 1-bromopropane as neutral marker. To detect HA in the ICP-MS and separate between HA complexed and non complexed metal ions in the CE-ICP-MS, we have halogenated the HA with iodine as ICP-MS marker.

  20. Glycolic Acid Silences Inflammasome Complex Genes, NLRC4 and ASC, by Inducing DNA Methylation in HaCaT Cells.

    Science.gov (United States)

    Tang, Sheau-Chung; Yeh, Jih-I; Hung, Sung-Jen; Hsiao, Yu-Ping; Liu, Fu-Tong; Yang, Jen-Hung

    2016-03-01

    AHAs (α-hydroxy acids), including glycolic acid (GA), have been widely used in cosmetic products and superficial chemical peels. Inflammasome complex has been shown to play critical roles in inflammatory pathways in human keratinocytes. However, the anti-inflammatory mechanism of GA is still unknown. The aim of this study is to investigate the relationship between the expression of the inflammasome complex and epigenetic modification to elucidate the molecular mechanism of the anti-inflammatory effect of GA in HaCaT cells. We evaluated NLRP3, NLRC4, AIM2, and ASC inflammasome complex gene expression on real-time polymerase chain reaction (PCR). Methylation changes were detected in these genes following treatment with DNA methyltransferase (DNMT) inhibitor 5-aza-2'-deoxycytidine (5-Aza) with or without the addition of GA using methylation-specific PCR (MSP). GA inhibited the expressions of these inflammasome complex genes, and the decreases in the expressions of mRNA were reversed by 5-Aza treatment. Methylation was detected in NLRC4 and ASC on MSP, but not in NLRP3 or AIM2. GA decreased NLRC4 and ASC gene expression by increasing not only DNA methyltransferase 3B (DNMT-3B) protein level, but also total DNMT activity. Furthermore, silencing of DNMT-3B (shDNMT-3B) increased the expressions of NLRC4 and ASC. Our data demonstrated that GA treatment induces hypermethylation of promoters of NLRC4 and ASC genes, which may subsequently lead to the hindering of the assembly of the inflammasome complex in HaCaT cells. These results highlight the anti-inflammatory potential of GA-containing cosmetic agents in human skin cells and demonstrate for the first time the role of aberrant hypermethylation in this process.

  1. The complex and important cellular and metabolic functions of saturated fatty acids.

    Science.gov (United States)

    Legrand, Philippe; Rioux, Vincent

    2010-10-01

    This review summarizes recent findings on the metabolism and biological functions of saturated fatty acids (SFA). Some of these findings show that SFA may have important and specific roles in the cells. Elucidated biochemical mechanisms like protein acylation (N-myristoylation, S-palmitoylation) and regulation of gene transcription are presented. In terms of physiology, SFA are involved for instance in lipogenesis, fat deposition, polyunsaturated fatty acids bioavailability and apoptosis. The variety of their functions demonstrates that SFA should no longer be considered as a single group.

  2. Melanin and humic acid-like polymer complex from olive mill waste waters. Part I. Isolation and characterization.

    Science.gov (United States)

    Khemakhem, Maissa; Papadimitriou, Vassiliki; Sotiroudis, Georgios; Zoumpoulakis, Panagiotis; Arbez-Gindre, Cécile; Bouzouita, Nabiha; Sotiroudis, Theodore G

    2016-07-15

    A water soluble humic acid and melanin-like polymer complex (OMWW-ASP) was isolated from olive mill waste waters (OMWW) by ammonium sulfate fractionation to be used as natural additive in food preparations. The dark polymer complex was further characterized by a variety of biochemical, physicochemical and spectroscopic techniques. OMWW-ASP is composed mainly of proteins associated with polyphenols and carbohydrates and the distribution of its relative molecular size was determined between about 5 and 190 kDa. SDS-PAGE shows the presence of a well separated protein band of 21.3 kDa and a low molecular weight peptide. The OMWW-ASP complex exhibits a monotonically increasing UV-Vis absorption spectrum and it contains stable radicals. Antioxidant activity measurements reveal the ability of the OMWW protein fraction to scavenge both the cationic 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(+)) radical, as well as the stable nitroxide free radical 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPOL). Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Copper(II) complexation by humic and fulvic acids from pig slurry and amended and non-amended soils.

    Science.gov (United States)

    Plaza, C; Senesi, N; García-Gil, J C; Polo, A

    2005-11-01

    The effect of the consecutive annual additions of pig slurry at rates of 0 (control), 90 and 150 m3 ha(-1) y(-1) over a 4-year period on the binding affinity for Cu(II) of soil humic acids (HAs) and fulvic acids (FAs) was investigated in a field plot experiment under semiarid conditions. A ligand potentiometric titration method and a single site model were used for determining the Cu(II) complexing capacities and the stability constants of Cu(II) complexes of HAs and FAs isolated from pig slurry and control and amended soils. The HAs complexing capacities and stability constants were larger than those of the corresponding FA fractions. With respect to the control soil HA, pig-slurry HA was characterized by a much smaller binding capacity and stability constant. Amendment with pig slurry decreased the binding affinity of soil HAs. Similar to the corresponding HAs, the binding affinity of pig-slurry FA was much smaller while that of amended-soil FAs were slightly smaller when compared to the control soil FA. The latter effect was, however, more evident with increasing the amount of pig slurry applied to soil per year and the number of years of pig slurry application.

  4. DISTRIBUTION OF LANTHANIDE AND ACTINIDE ELEMENTS BETWEEN BIS-(2-ETHYLHEXYL)PHOSPHORIC ACID AND BUFFERED LACTATE SOLUTIONS CONTAINING SELECTED COMPLEXANTS

    Energy Technology Data Exchange (ETDEWEB)

    Rudisill, Tracy S.; Diprete, David P.; Thompson, Major C.

    2013-04-15

    With the renewed interest in the closure of the nuclear fuel cycle, the TALSPEAK process is being considered for the separation of Am and Cm from the lanthanide fission products in a next generation reprocessing plant. However, an efficient separation requires tight control of the pH which likely will be difficult to achieve on a large scale. To address this issue, we measured the distribution of lanthanide and actinide elements between aqueous and organic phases in the presence of complexants which were potentially less sensitive to pH control than the diethylenetriaminepentaacetic (DTPA) used in the process. To perform the extractions, a rapid and accurate method was developed for measuring distribution coefficients based on the preparation of lanthanide tracers in the Savannah River National Laboratory neutron activation analysis facility. The complexants tested included aceto-, benzo-, and salicylhydroxamic acids, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), and ammonium thiocyanate (NH{sub 4}SCN). The hydroxamic acids were the least effective of the complexants tested. The separation factors for TPEN and NH{sub 4}SCN were higher, especially for the heaviest lanthanides in the series; however, no conditions were identified which resulted in separations factors which consistently approached those measured for the use of DTPA.

  5. Preparation of polyelectrolyte complex nanoparticles of chitosan and poly(2-acry1amido-2-methylpropanesulfonic acid) for doxorubicin release.

    Science.gov (United States)

    Zhang, Liping; Wang, Jie; Ni, Caihua; Zhang, Yanan; Shi, Gang

    2016-01-01

    A new kind of polyelectrolyte complex (PEC) based on cationic chitosan (CS) and anionic poly(2-acry1amido-2-methylpropanesulfonic acid) (PAMPS) was prepared using a polymer-monomer pair reaction system. Chitosan was mixed with 2-acry1amido-2-methylpropanesulfonic acid) (AMPS) in an aqueous solution, followed by polymerization of AMPS. The complex was formed by electrostatic interaction of NH3(+) groups of CS and SO3(-) groups of AMPS, leading to a formation of complex nanoparticles of CS-PAMPS. A series of nanoparticles were obtained by changing the weight ratio of CS to AMPS, the structure and properties of nanoparticles were investigated. It was observed that the nanoparticles possessed spherical morphologies with average diameters from 255 nm to 390 nm varied with compositions of the nanoparticles. The nanoparticles were used as drug vehicles for doxorubicin, displaying relative high drug loading rate and encapsulation rate. The vitro release profiles revealed that the drug release could be controlled by adjusting pH of the release media. The nanoparticles demonstrated apparent advantages such as simple preparation process, free of organic solvents, size controllable, good biodegradability and biocompatibility, and they could be potentially used in drug controlled release field.

  6. TOR complex 2-Ypk1 signaling is an essential positive regulator of the general amino acid control response and autophagy.

    Science.gov (United States)

    Vlahakis, Ariadne; Graef, Martin; Nunnari, Jodi; Powers, Ted

    2014-07-22

    The highly conserved Target of Rapamycin (TOR) kinase is a central regulator of cell growth and metabolism in response to nutrient availability. TOR functions in two structurally and functionally distinct complexes, TOR Complex 1 (TORC1) and TOR Complex 2 (TORC2). Through TORC1, TOR negatively regulates autophagy, a conserved process that functions in quality control and cellular homeostasis and, in this capacity, is part of an adaptive nutrient deprivation response. Here we demonstrate that during amino acid starvation TOR also operates independently as a positive regulator of autophagy through the conserved TORC2 and its downstream target protein kinase, Ypk1. Under these conditions, TORC2-Ypk1 signaling negatively regulates the Ca(2+)/calmodulin-dependent phosphatase, calcineurin, to enable the activation of the amino acid-sensing eIF2α kinase, Gcn2, and to promote autophagy. Our work reveals that the TORC2 pathway regulates autophagy in an opposing manner to TORC1 to provide a tunable response to cellular metabolic status.

  7. Molecular simulation of N-acetylneuraminic acid analogs and molecular dynamics studies of cholera toxin-Neu5Gc complex.

    Science.gov (United States)

    Blessy, J Jino; Sharmila, D Jeya Sundara

    2015-01-01

    Cholera toxin (CT) is an AB5 protein complex secreted by the pathogen Vibrio cholera, which is responsible for cholera infection. N-acetylneuraminic acid (NeuNAc) is a derivative of neuraminic acid with nine-carbon backbone. NeuNAc is distributed on the cell surface mainly located in the terminal components of glycoconjugates, and also plays an important role in cell-cell interaction. In our current study, molecular docking and molecular dynamic (MD) simulations were implemented to identify the potent NeuNAc analogs with high-inhibitory activity against CT protein. Thirty-four NeuNAc analogs, modified in different positions C-1/C-2/C-4/C-5/C-7/C-8/C-9, were modeled and docked against the active site of CT protein. Among the 34 NeuNAc analogs, the analog Neu5Gc shows the least extra precision glide score of -9.52 and glide energy of -44.71 kcal/mol. NeuNAc analogs block the CT active site residues HIS:13, ASN:90, LYS:91, GLN:56, GLN:61, and TRP:88 through intermolecular hydrogen bonding. The MD simulation for CT-Neu5Gc docking complex was performed using Desmond. MD simulation of CT-Neu5Gc complex reveals the stable nature of docking interaction.

  8. STUDY OF CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE OVER A BIDENTATE POLYMER BOUND CIS-DICARBONYLRHODIUM COMPLEX AS CATALYST

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaojun; LIU Zhongyang; PAN Pinglai; YUAN Guoqing

    1996-01-01

    Copolymer of 2-vinylpyridine and vinylacetate coordinated with dicarbonylrhodium used as a catalyst for carbonylation of methanol to acetic acid and anhydride has been studied. The structural characteristics of the copolymer ligand and complex, and the influences of the reaction conditions on the carbonylation catalyzed by this polymer complex have been investigated. In comparison with small molecule catalyst of Rh complex, the bidentate copolymer coordinated complex has better thermal stability. The reaction mechanism of the carbonylation reaction is also illustrated.

  9. Structural Analysis of Crystalline R(+)-α-Lipoic Acid-α-cyclodextrin Complex Based on Microscopic and Spectroscopic Studies.

    Science.gov (United States)

    Ikuta, Naoko; Endo, Takatsugu; Hosomi, Shota; Setou, Keita; Tanaka, Shiori; Ogawa, Noriko; Yamamoto, Hiromitsu; Mizukami, Tomoyuki; Arai, Shoji; Okuno, Masayuki; Takahashi, Kenji; Terao, Keiji; Matsugo, Seiichi

    2015-10-16

    R(+)-α-lipoic acid (RALA) is a naturally-occurring substance, and its protein-bound form plays significant role in the energy metabolism in the mitochondria. RALA is vulnerable to a variety of physical stimuli, including heat and UV light, which prompted us to study the stability of its complexes with cyclodextrins (CDs). In this study, we have prepared and purified a crystalline RALA-αCD complex and evaluated its properties in the solid state. The results of ¹H NMR and PXRD analyses indicated that the crystalline RALA-αCD complex is a channel type complex with a molar ratio of 2:3 (RALA:α-CD). Attenuated total reflection/Fourier transform infrared analysis of the complex showed the shift of the C=O stretching vibration of RALA due to the formation of the RALA-αCD complex. Raman spectroscopic analysis revealed the significant weakness of the S-S and C-S stretching vibrations of RALA in the RALA-αCD complex implying that the dithiolane ring of RALA is almost enclosed in glucose ring of α-CD. Extent of this effect was dependent on the direction of the excitation laser to the hexagonal morphology of the crystal. Solid-state NMR analysis allowed for the chemical shift of the C=O peak to be precisely determined. These results suggested that RALA was positioned in the α-CD cavity with its 1,2-dithiolane ring orientated perpendicular to the plane of the α-CD ring.

  10. Study on the Structure of Supramolecular Inclusion Complex of b-Cyclodextrin with Retinoic Acid

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Inclusion compound of retinoic acid with b-cyclodextrin was prepared by coprecipitating method, the structure of resulting product was studied by elemental analysis, differential scanning caloriemetry(DSC) analysis, FT-IR spectroscopy and X-ray diffractometry, and the formed supramolecule self-assembles in aqueous solution according to molar ratio 2:1 of host-guest.

  11. Catalytic activity of thiacalix[4]arenetetrasulfonate metal complexes on modified anion-exchangers for ascorbic acid oxidation.

    Science.gov (United States)

    Odo, Junichi; Hirashima, Tomomi; Hayashida, Tomoko; Miyauchi, Asuka; Minemoto, Mami; Iuchi, Masato; Inoguchi, Masahiko

    2013-01-01

    The catalysis of ascorbic acid (AsA) oxidation by anion-exchangers modified with metal complexes of thiacalix[4]arenetetrasulfonate (Me-TCAS[4]A-500, Me=Mn(3+), Fe(3+), Co(3+), Ce(4+), Cu(2+), Zn(2+), Ni(2+), and H2) were investigated. Me-TCAS[4]A-500 (Me=Mn(3+), Fe(3+), Ce(4+), and Cu(2+)) all exhibited the ability to catalyze the oxidative reaction of AsA to dehydroascorbic acid. However, in the presence of high concentrations of AsA, only Cu(2+)-TCAS[4]A-500 was capable of complete oxidation of the acid. Moreover, after six repeat uses, Cu(2+)-TCAS[4]A-500 maintained high and relatively constant catalytic activity. Prior treatment of glucose solutions with Cu(2+)-TCAS[4]A-500, even in the presence of high AsA concentrations, enabled the satisfactory determination of glucose without interference by AsA. Cu(2+)-TCAS[4]A-500 will therefore be applicable as an artificial substitute for ascorbate oxidase, and may be useful as a means to eliminate AsA interference during the analysis of vital compounds such as glucose and uric acid.

  12. Solvent-mediated pseudo-quadruple hydrogen-bond motifs in three lamotrigine-carboxylic acid complexes.

    Science.gov (United States)

    Sridhar, Balasubramanian; Nanubolu, Jagadeesh Babu; Ravikumar, Krishnan

    2013-10-01

    Lamotrigine, an antiepileptic drug, has been complexed with three aromatic carboxylic acids. All three compounds crystallize with the inclusion of N,N-dimethylformamide (DMF) solvent, viz. lamotriginium [3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazin-2-ium] 4-iodobenzoate N,N-dimethylformamide monosolvate, C9H8Cl2N5(+)·C7H4IO2(-)·C3H7NO, (I), lamotriginium 4-methylbenzoate N,N-dimethylformamide monosolvate, C9H7Cl2N5(+)·C8H8O2(-)·C3H7NO, (II), and lamotriginium 3,5-dinitro-2-hydroxybenzoate N,N-dimethylformamide monosolvate, C9H8Cl2N5(+)·C7H3N2O7(-)·C3H7NO, (III). In all three structures, proton transfer takes place from the acid to the lamotrigine molecule. However, in (I) and (II), the acidic H atom is disordered over two sites and there is only partial transfer of the H atom from O to N. In (III), the corresponding H atom is ordered and complete proton transfer has occurred. Lamotrigine-lamotrigine, lamotrigine-acid and lamotrigine-solvent interactions are observed in all three structures and they thereby exhibit isostructurality. The DMF solvent extends the lamotrigine-lamotrigine dimers into a pseudo-quadruple hydrogen-bonding motif.

  13. A solid-state sensor based on ruthenium (II) complex immobilized on polytyramine film for the simultaneous determination of dopamine, ascorbic acid and uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Khudaish, Emad A., E-mail: ejoudi@squ.edu.om [Sultan Qaboos University, College of Science, Chemistry Department, PO Box 36, PC 123 Muscat (Oman); Al-Ajmi, Khawla Y. [Sultan Qaboos University, College of Science, Chemistry Department, PO Box 36, PC 123 Muscat (Oman); Al-Harthi, Salim H. [Sultan Qaboos University, College of Science, Department of Physics, PO Box 36, PC 123 Muscat (Oman)

    2014-08-01

    A solid-state sensor based on a polytyramine (Pty) film deposited on a glassy carbon electrode doped with a tris(2,2′-bipyridyl)Ru(II) complex (Ru/Pty/GCE) was constructed electrochemically. The surface morphology of the film modified electrode was characterized using electrochemical and surface scanning techniques. A redox property represented by a [Ru(bpy){sub 3}]{sup 3+/2+} couple immobilized at the Pty moiety was characterized using typical voltammetric techniques. A distinct Ru 3d peak obtained at 280.9 eV confirms doping of the Ru species onto the Pty moiety characterized by X-ray photoelectron (XPS). Atomic force microscopy (AFM) images demonstrate that incorporation of Ru decreases the surface roughness of the native Pty film modified electrode. The Ru/Pty/GCE exhibits efficient electrochemical sensing toward the oxidation of dopamine (DA), ascorbic acid (AA) and uric acid (UA) in their mixture. Three well-defined peaks were resolved with a large peak to peak separation and the detection limits of AA, DA and UA are brought down to 0.31, 0.08 and 0.58 μM, respectively. Interference studies and application for DA determination in real samples were conducted with satisfactory results. - Highlights: • XPS data confirm doping of ruthenium onto the polytyramine moiety. • The voltammetric signals of ascorbic acid, dopamine and uric acid are well defined. • The sensor is stable and offers a large adsorption facility for all species. • The sensor is highly sensitive to dopamine oxidation. • The sensor is applied to a real sample with a satisfactory recovery percentage.

  14. Synthesis, Catalysis of Rare Earth Complexes with Aliphatic Noncyclic Polyether-Amino Acid Schiff Base

    Institute of Scientific and Technical Information of China (English)

    Li Ning; Yao Kemin; Shen Lianfang

    2005-01-01

    Eleven new rare earth complexes with aliphatic Schiff base, condensed from diglycol aldehyde and bis-arginine, were synthesized and characterized. They are confirmed as Ln(H2DAAR)(NO3)3·7H2O (Ln=La, Pr, Nd, Gd), Ln3(H2DAAR)2(NO3)9·5H2O (Ln=Dy, Y) and Ln2(H2DAAR)(NO3)6·3H2O (Ln=La, Nd, Sm, Gd), Ln3(DAAR)(NO3)7·4H2O (Ln=Dy, Yb, Y) respectively under different molar ratios of metal to ligand (DAAR=diglycol aldehyde bis-arginine). The present paper deals with a synthetic method and catalytic properties of obtained complexes. The result shows that proper pH value is important for synthesis of the complexes and compositions of the lighter and the heavier rare earth complexes are different under the same reaction condition. Some new complexes obtained have proved their catalytic activity and 80% conversion with the viscosity-average molecular weight 230,000 for the polymerization of methyl methacrylate (MMA) without addition of any cocatalyst.

  15. Acid phosphatase complex from the freshwater snail Viviparus viviparus L. under standard conditions and intoxication by cadmium ions.

    Science.gov (United States)

    Tsvetkov, I L; Popov, A P; Konichev, A S

    2003-12-01

    Acid phosphatases differing in both subcellular localization and substrate specificity were isolated for the first time from the liver of the freshwater snail Viviparus viviparus L. by preparative isoelectrofocusing. One of five characterized phosphatases is highly specific to ADP and the others can hydrolyze (at variable rate) a series of natural substrates. A scheme is proposed for the involvement of the studied phosphatases in carbohydrate metabolism. We have also studied some peculiarities of the effect of Cd2+ in vitro and in vivo on the activities of individual components of the acid phosphatase complex and corresponding changes in metabolism of the freshwater snail as a new test-object allowing the estimation of toxicity in water.

  16. Cyclopiazonic Acid Is Complexed to a Divalent Metal Ion When Bound to the Sarcoplasmic Reticulum Ca2+-ATPase

    DEFF Research Database (Denmark)

    Laursen, Mette; Bublitz, Maike; Moncoq, Karine;

    2009-01-01

    Abstract: We have determined the structure of the sarco(endo) plasmic reticulum Ca2+-ATPase (SERCA) in an E2.P-i-like form stabilized as a complex with MgF42-, an ATP analog, adenosine 5'-(beta,gamma-methylene) triphosphate (AMPPCP), and cyclopiazonic acid (CPA). The structure determined at 2.......5 angstrom resolution leads to a significantly revised model of CPA binding when compared with earlier reports. It shows that a divalent metal ion is required for CPA binding through coordination of the tetramic acid moiety at a characteristic kink of the M1 helix found in all P-type ATPase structures, which...... is expected to be part of the cytoplasmic cation access pathway. Our model is consistent with the biochemical data on CPA function and provides new measures in structure-based drug design targeting Ca2+-ATPases, e. g. from pathogens. We also present an extended structural basis of ATP modulation pinpointing...

  17. Reaction between the Pt(II)-complexes and the amino acids of the β-amyloid peptide

    Science.gov (United States)

    Novato, Willian T. G.; Stroppa, Pedro Henrique F.; Da Silva, Adilson D.; Botezine, Naiara P.; Machado, Flávia C.; Costa, Luiz Antônio S.; Dos Santos, Hélio F.

    2017-01-01

    Reaction between [Pt(ophen)Cl2] and HIS was monitored and the solvolysis (k1) and Cl/HIS ligand exchange (k2) rate constants obtained. The k1 and k2 were (6.2 ± 0.4) × 10-5 s-1 and 52.8 × 10-2 M-1 s-1, respectively. The corresponding calculated values were 47.5 × 10-5 s-1 and 52.2 × 10-2 M-1 s-1, in agreement with the experiment. Calculations were used to establish the reactivity order for a set of amino acids: MET ∼ LYS ∼ HIS(ε) > GLU ∼ ASP >> ASN ∼ GLN. In spite of the similar reactivity among MET, LYS and HIS, the thermodynamics suggests the reactions with LYS and HIS more favorable than with MET. Therefore, N-containing amino acids should be potential targets of Pt(II)-complexes in β-amyloid.

  18. Synthesis, structure and stability of a chiral imine-based Schiff-based ligand derived from L-glutamic acid and its [Cu4] complex

    Science.gov (United States)

    Muche, Simon; Levacheva, Irina; Samsonova, Olga; Biernasiuk, Anna; Malm, Anna; Lonsdale, Richard; Popiołek, Łukasz; Bakowsky, Udo; Hołyńska, Małgorzata

    2017-01-01

    Studies of the stability of a ligand derived from L-glutamic acid and ortho-vanillin and its new [Cu4] complex are presented. The [Cu4] complex contains a heterocubane [CuII4O4] core and pendant carboxylic groups increasing its solubility in water, also under basic conditions. The stability of the complex in different solvents is confirmed with ESI-MS studies and such experiments as successful recrystallization. The complex is stable also under physiological conditions whereas the ligand is partly decomposed to L-glutamic acid and ortho-vanillin.

  19. UV-induced photoreaction pathways of salicylic acid: Identification of the fourth stable conformer and ketoketene-water complex

    Science.gov (United States)

    Miyagawa, Masaya; Akai, Nobuyuki; Nakata, Munetaka

    2014-05-01

    Photoreaction pathways of salicylic acid have been investigated by the low-temperature matrix-isolation infrared spectroscopy with an aid of the density-functional-theory calculations. Only the most stable E form existed in an argon matrix. The second stable R form and the fourth stable H form were produced by UV irradiation (λ > 290 nm). The third stable O form was assumed to return immediately to E form even if it was produced. Ketoketene-water complex was yielded from R form by dissociation of the H and OH parts interacting through intramolecular hydrogen bonding upon prolonged UV irradiation.

  20. Kinetics and mechanism of oxidation of glycine by iron(III)-1,10-phenanthroline complex in perchloric acid medium

    Indian Academy of Sciences (India)

    T V N Partha Sarathi; A Kalyan Kumar; K Krishna Kishore; P Vani

    2005-07-01

    Kinetics and mechanism of oxidation of glycine by iron(III)-1,10-phenanthroline complex has been studied in perchloric acid medium. The reaction is first order with respect to iron(III) and glycine. An increase in (phenanthroline) increases the rate, while increase in [H+] decreases the rate. Hence it can be inferred that the reactive species of the substrate is the zwitterionic form and that of the oxidant is [Fe(phen)2(H2O)2]3+. The proposed mechanism leads to the rate law as elucidated.