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Sample records for 8-quinolinol

  1. Preconcentration of trace metals from sea water with 7-dodecenyl-8-quinolinol impregnated macroporous resin

    SciTech Connect

    Isshiki, K.; Tsuji, F.; Kuwamoto, T.; Nakayama, E.

    1987-10-15

    7-Dodecenyl-8-quinolinol (DDQ) impregnated XAD-4 resin (DDQ resin) was prepared, and its extraction behavior was studied and compared with solvent extraction with DDQ for Aq, Al, Bi, Cd, Cu, Fe, Ga, Mn, Ni, Pb, and Ti. The results demonstrate that the DDQ resin is effective in the preconcentration of those metals from sea water. The column extraction method using the DDQ resin was applied to sea water analysis with satisfactory results being obtained.

  2. Structural and spectroscopic characterization of 2,2‧-methylenedi-8-quinolinol dihydrochloride dihydrate

    NASA Astrophysics Data System (ADS)

    Zinczuk, J.; Piro, O. E.; Castellano, E. E.; Baran, E. J.

    2008-12-01

    The crystal structure of the title compound, a promising ligand for chelatoterapies in the treatment of Alzheimer's disease, has been determined by single crystal X-ray diffractometry. The compound crystallized in the monoclinic space group C2/c with Z = 4. The dimeric 8-quinolinol molecule is sited on a crystallographic twofold axis passing through the CH 2 carbon atom that links the symmetry related molecular halves, giving rise to a two-bladed propeller-like conformation. The 1H and 13C NMR as well as the FT-IR and Raman spectra of the compound were also recorded and are briefly discussed. Some comparisons with spectra of related species are made.

  3. Electrochemistry of oxo-technetium(V) complexes containing Schiff base and 8-quinolinol ligands

    SciTech Connect

    Refosco, F.; Mazzi, U.; Deutsch, E.; Kirchhoff, J.R.; Heineman, W.R.; Seeber, R.

    1988-11-16

    The electrochemistry of six-coordinate, monooxo technetium(V) complexes containing Schiff base ligands has been studied in acetonitrile and N,N'-dimethylformamide solutions. The complexes have the general formula TcOCl(L/sub B/)/sub 2/ or TcO(L/sub T/)(L/sub B/), where L/sub B/ represents a bidentate-N,O Schiff base ligand or a bidentate-N,O 8-quinolinol ligand and L/sub T/ represents a tridentate-O,N,O Schiff base ligand. Cyclic voltammetry at a platinum-disk electrode, controlled-potential coulometry, and thin-layer spectroelectrochemistry were used to probe both the oxidation and the reduction of these complexes. The results of these studies, and previously reported results on the analogous Re(V) complexes, can be understood within a single general reaction scheme. The salient features of this scheme are (i) one-electron reduction of Tc(V) to Tc(IV), (ii) subsequent loss of a ligand situated cis to the Tc/identical to/O linkage, and (iii) subsequent isomerization of this unstable Tc(IV) product to more stable complex in which the site trans to the Tc/identical to/O linkage is vacant. The Tc(IV) complexes can also be reduced to analogous Tc(III) species, which appear to undergo the same ligand loss and isomerization reactions. The technetium complexes are 400-500 mV easier to reduce than are their rhenium analogues. The 8-quinolinol ligands, and especially the 5-nitro derivative, both thermodynamically and kinetically stabilize the Tc(IV) and Tc(III) oxidation states. These electrogenerated species are unusual in that they constitute the bulk of the known examples of monomeric Tc(IV) and Tc(III) complexes containing only N- and O-donating ligands. 34 refs., 9 figs., 1 tab.

  4. Solid-phase extraction of gallium(III) with hydrophobic 8-quinolinol derivatives-impregnated resin from aqueous acidic and alkaline solutions.

    PubMed

    Hatori, Nahoko; Imura, Hisanori; Ohashi, Akira; Ohashi, Kousaburo

    2008-12-01

    Solid-phase extraction (SPE) of gallium(III) with hydrophobic 8-quinolinol derivatives (HQs)-impregnated resin from aqueous acidic and alkaline solutions has been investigated. The HQs used were 7-(4-ethyl-1-methyloctyl)-8-quinolinol (HEMOQ), 5-octyloxymethyl-8-quinolinol (HO(8)Q), 2-methyl-5-octyloxymethyl-8-quinolinol (HMO(8)Q), 5-dioctylaminomethyl-8-quinolinol (HN(8)Q), 7-bromo-5-octyloxymethyl-8-quinolinol (HBrO(8)Q), and 5-(2-ethylhexyloxymethyl)-8-quinolinol (HOEHQ). Various factors affecting the SPE, such as the substituents of the HQs, HCl and NaOH concentrations in the aqueous phase, the HQ concentration in the resin, and the equilibration time were clarified. The extractability for gallium(III) from the aqueous solution became higher in the following order: HBrO(8)Q < HEMOQ < HO(8)Q < HN(8)Q < HMO(8)Q at 3 mol l(-1) HCl; HMO(8)Q < HO(8)Q < HOEHQ < HEMOQ < HN(8)Q < HBrO(8)Q at pH 0.4; HMO(8)Q < HO(8)Q asymptotically equal to HOEHQ < HN(8)Q < HEMOQ at 3 mol l(-1) NaOH.

  5. Simple activation by acid of latent Ru-NHC-based metathesis initiators bearing 8-quinolinolate co-ligands

    PubMed Central

    Wappel, Julia; Fischer, Roland C; Cavallo, Luigi; Slugovc, Christian

    2016-01-01

    Summary A straightforward synthesis utilizing the ring-opening metathesis polymerization (ROMP) reaction is described for acid-triggered N,O-chelating ruthenium-based pre-catalysts bearing one or two 8-quinolinolate ligands. The innovative pre-catalysts were tested regarding their behavior in ROMP and especially for their use in the synthesis of poly(dicyclopentadiene) (pDCPD). Bearing either the common phosphine leaving ligand in the first and second Grubbs olefin metathesis catalysts, or the Ru–O bond cleavage for the next Hoveyda-type catalysts, this work is a step forward towards the control of polymer functionalization and living or switchable polymerizations. PMID:26877818

  6. Simple activation by acid of latent Ru-NHC-based metathesis initiators bearing 8-quinolinolate co-ligands.

    PubMed

    Wappel, Julia; Fischer, Roland C; Cavallo, Luigi; Slugovc, Christian; Poater, Albert

    2016-01-01

    A straightforward synthesis utilizing the ring-opening metathesis polymerization (ROMP) reaction is described for acid-triggered N,O-chelating ruthenium-based pre-catalysts bearing one or two 8-quinolinolate ligands. The innovative pre-catalysts were tested regarding their behavior in ROMP and especially for their use in the synthesis of poly(dicyclopentadiene) (pDCPD). Bearing either the common phosphine leaving ligand in the first and second Grubbs olefin metathesis catalysts, or the Ru-O bond cleavage for the next Hoveyda-type catalysts, this work is a step forward towards the control of polymer functionalization and living or switchable polymerizations. PMID:26877818

  7. A High-Throughput Cell-Based Screen Identified a 2-[(E)-2-Phenylvinyl]-8-Quinolinol Core Structure That Activates p53.

    PubMed

    Bechill, John; Zhong, Rong; Zhang, Chen; Solomaha, Elena; Spiotto, Michael T

    2016-01-01

    p53 function is frequently inhibited in cancer either through mutations or by increased degradation via MDM2 and/or E6AP E3-ubiquitin ligases. Most agents that restore p53 expression act by binding MDM2 or E6AP to prevent p53 degradation. However, fewer compounds directly bind to and activate p53. Here, we identified compounds that shared a core structure that bound p53, caused nuclear localization of p53 and caused cell death. To identify these compounds, we developed a novel cell-based screen to redirect p53 degradation to the Skip-Cullin-F-box (SCF) ubiquitin ligase complex in cells expressing high levels of p53. In a multiplexed assay, we coupled p53 targeted degradation with Rb1 targeted degradation in order to identify compounds that prevented p53 degradation while not inhibiting degradation through the SCF complex or other proteolytic machinery. High-throughput screening identified several leads that shared a common 2-[(E)-2-phenylvinyl]-8-quinolinol core structure that stabilized p53. Surface plasmon resonance analysis indicated that these compounds bound p53 with a KD of 200 ± 52 nM. Furthermore, these compounds increased p53 nuclear localization and transcription of the p53 target genes PUMA, BAX, p21 and FAS in cancer cells. Although p53-null cells had a 2.5±0.5-fold greater viability compared to p53 wild type cells after treatment with core compounds, loss of p53 did not completely rescue cell viability suggesting that compounds may target both p53-dependent and p53-independent pathways to inhibit cell proliferation. Thus, we present a novel, cell-based high-throughput screen to identify a 2-[(E)-2-phenylvinyl]-8-quinolinol core structure that bound to p53 and increased p53 activity in cancer cells. These compounds may serve as anti-neoplastic agents in part by targeting p53 as well as other potential pathways.

  8. A High-Throughput Cell-Based Screen Identified a 2-[(E)-2-Phenylvinyl]-8-Quinolinol Core Structure That Activates p53

    PubMed Central

    Bechill, John; Zhong, Rong; Zhang, Chen; Solomaha, Elena

    2016-01-01

    p53 function is frequently inhibited in cancer either through mutations or by increased degradation via MDM2 and/or E6AP E3-ubiquitin ligases. Most agents that restore p53 expression act by binding MDM2 or E6AP to prevent p53 degradation. However, fewer compounds directly bind to and activate p53. Here, we identified compounds that shared a core structure that bound p53, caused nuclear localization of p53 and caused cell death. To identify these compounds, we developed a novel cell-based screen to redirect p53 degradation to the Skip-Cullin-F-box (SCF) ubiquitin ligase complex in cells expressing high levels of p53. In a multiplexed assay, we coupled p53 targeted degradation with Rb1 targeted degradation in order to identify compounds that prevented p53 degradation while not inhibiting degradation through the SCF complex or other proteolytic machinery. High-throughput screening identified several leads that shared a common 2-[(E)-2-phenylvinyl]-8-quinolinol core structure that stabilized p53. Surface plasmon resonance analysis indicated that these compounds bound p53 with a KD of 200 ± 52 nM. Furthermore, these compounds increased p53 nuclear localization and transcription of the p53 target genes PUMA, BAX, p21 and FAS in cancer cells. Although p53-null cells had a 2.5±0.5-fold greater viability compared to p53 wild type cells after treatment with core compounds, loss of p53 did not completely rescue cell viability suggesting that compounds may target both p53-dependent and p53-independent pathways to inhibit cell proliferation. Thus, we present a novel, cell-based high-throughput screen to identify a 2-[(E)-2-phenylvinyl]-8-quinolinol core structure that bound to p53 and increased p53 activity in cancer cells. These compounds may serve as anti-neoplastic agents in part by targeting p53 as well as other potential pathways. PMID:27124407

  9. A High-Throughput Cell-Based Screen Identified a 2-[(E)-2-Phenylvinyl]-8-Quinolinol Core Structure That Activates p53.

    PubMed

    Bechill, John; Zhong, Rong; Zhang, Chen; Solomaha, Elena; Spiotto, Michael T

    2016-01-01

    p53 function is frequently inhibited in cancer either through mutations or by increased degradation via MDM2 and/or E6AP E3-ubiquitin ligases. Most agents that restore p53 expression act by binding MDM2 or E6AP to prevent p53 degradation. However, fewer compounds directly bind to and activate p53. Here, we identified compounds that shared a core structure that bound p53, caused nuclear localization of p53 and caused cell death. To identify these compounds, we developed a novel cell-based screen to redirect p53 degradation to the Skip-Cullin-F-box (SCF) ubiquitin ligase complex in cells expressing high levels of p53. In a multiplexed assay, we coupled p53 targeted degradation with Rb1 targeted degradation in order to identify compounds that prevented p53 degradation while not inhibiting degradation through the SCF complex or other proteolytic machinery. High-throughput screening identified several leads that shared a common 2-[(E)-2-phenylvinyl]-8-quinolinol core structure that stabilized p53. Surface plasmon resonance analysis indicated that these compounds bound p53 with a KD of 200 ± 52 nM. Furthermore, these compounds increased p53 nuclear localization and transcription of the p53 target genes PUMA, BAX, p21 and FAS in cancer cells. Although p53-null cells had a 2.5±0.5-fold greater viability compared to p53 wild type cells after treatment with core compounds, loss of p53 did not completely rescue cell viability suggesting that compounds may target both p53-dependent and p53-independent pathways to inhibit cell proliferation. Thus, we present a novel, cell-based high-throughput screen to identify a 2-[(E)-2-phenylvinyl]-8-quinolinol core structure that bound to p53 and increased p53 activity in cancer cells. These compounds may serve as anti-neoplastic agents in part by targeting p53 as well as other potential pathways. PMID:27124407

  10. Structural, electronic, vibrational and NMR spectral analyses of [Ru(OAc)(2cqn)2NO] (H2cqn=2-chloro-8-quinolinol) isomers.

    PubMed

    Wang, Jianru; Zhao, Yan; Jin, Xiaowei; Yang, Li; Wang, Hongfei

    2014-03-25

    Geometries of three [Ru(OAc)(2cqn)2NO] (H2cqn=2-chloro-8-quinolinol) isomers were fully optimized with density functional theory (DFT), and compared with their crystal structures. Their electronic spectra, infrared and NMR spectra were also calculated at the B3LYP level with Lanl2dz and 6-311G(d,p) as the basis set. And good agreement had been achieved between experimental and theoretical values of structural parameter, UV-vis absorption and scaled vibration frequency. With the gauge independent atomic orbital (GIAO) method, chemical shifts in (1)H and (13)C NMR of these isomers were also calculated, which could reasonably match with the experimental data. The calculated frontier molecular orbitals suggested that the electronic transition from a ligand-based orbital to an antibonding overlap of the Ru(d) and π(∗) NO(p) control the photo-induced reactivity of [Ru(OAc)(2cqn)2NO] complexes. PMID:24334066

  11. Determination of rare earth elements in seawater by inductively coupled plasma mass spectrometry with on-line column pre-concentration using 8-quinolinole-immobilized fluorinated metal alkoxide glass

    NASA Astrophysics Data System (ADS)

    Kajiya, Tasuku; Aihara, Masato; Hirata, Shizuko

    2004-04-01

    The on-line column pre-concentration technique with inductively coupled plasma mass spectrometry (ICP-MS) has been developed using micro-column of 8-quinolinole-immobilized fluorinated metal alkoxide glass (MAF-8HQ). The aim of method was to determine rare earth elements (REEs) (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) in seawater. A 6.4 ml of seawater sample was passed through the column for 2 min, after washing the column with ultrapure water, the adsorbed REEs were subsequently eluted into the plasma with 1.4 M nitric acid. Sample pH, sampling and eluting flow rates and acidity of eluent were optimized. Detection limits (3 σ) based on three times standard deviations of water by 8 replicates were in the range from 0.11 pg ml -1 for Y to 0.30 pg ml -1 for Tb, and the precisions by a 10 pg ml -1 REEs standard solution ( n=8) were in the range from 4.7% for Tm to 8.7% for Tb and Yb. Analysis of one sample could be processed in 7 min. The proposed method was verified by determination of REEs in the two certified reference materials (CRMs) of seawater, CASS-4 and NASS-5, and the method was also applied to determine REEs in the costal seawater of Hiroshima Bay, the Seto Inland Sea, Japan.

  12. Studies of the degradation mechanism of organic light-emitting diodes based on tris(8-quinolinolate)aluminum Alq and 2-tert-butyl-9,10-di(2-naphthyl)anthracene TBADN

    NASA Astrophysics Data System (ADS)

    Jarikov, Viktor V.; Kondakov, Denis Y.

    2009-02-01

    Previously, radical cation of tris(8-quinolinolate)aluminum (Alq•+) has been associated with the instability of Alq films subjected to holes-only electrical current. Yet, the questions remain (i) whether Alq•+ is the primary source of the intrinsic degradation of bipolar organic light-emitting diodes (OLEDs) based on Alq, (ii) whether Alq•+ reactions result in deep charge traps in holes-only devices as found in bipolar counterparts, and (iii) whether radical cations can be a common source of degradation of OLEDs irrespective of materials. With regards to generality of hole-current-related degradation, it is interesting to examine the behavior of 9,10-diarylanthracenes (DAAs)—the practically important class of blue-fluorescing light-emitting-layer hosts. These questions prompted our comparative study of the effects of unipolar currents in Alq and 2-t-butyl-9,10-di(2-naphthyl)anthracene (TBADN), which was chosen as a representative material of the DAA class. First, we identified device structures allowing for rigorous and stable unipolar conduction. Interestingly, even in pristine holes-only devices, our voltammetric measurements indicated that Alq contains a substantial density of deep hole traps (far deeper than what can be explained by energetic disorder), which can be charged by passing holes-only current and seemingly discharged by exposure to white light. As for aged holes-only Alq devices, they exhibited symptoms qualitatively matching those of aged bipolar Alq devices, viz., photoluminescence (PL) loss, transition voltage (V0) rise, and drive voltage (Vd) rise. Notably, PL and V0 are linearly correlated in both holes-only and bipolar devices, which reinforces the supposed link between Alq•+ and the degradation in both types of devices. Yet, there are indications the Alq•+ instability may not be the only degradation pathway in bipolar devices. Even though our observations for holes-only Alq devices agree qualitatively with previously reported ones

  13. Opportunities for Low Cost Processing of Erbium 8-Quinolinolates for Active Integrated Photonic Applications.

    PubMed

    Penna, Stefano; Mattiello, Leonardo; Di Bartolo, Silvia; Pizzoleo, Angelo; Attanasio, Vincenzo; Beleffi, Giorgio Maria Tosi; Otomo, Akira

    2016-04-01

    Erbium-doped organic emitters are promising active materials for Photonic Integrated Circuits (PICs) due to their emission shown at 1550 nm combined to the potential low cost processing. In particular, Erbium Quinoline (ErQ) gained a strong interest in the last decade for the good emission efficiency. This contribution reports the results derived from the application of ErQ as active core material within a buried optical waveguide, following the development of a purposed optical process to control the refractive index of ErQ and then to define a patterned structure from a single thin film deposition step. The reported results show the potential of Er-doped organic materials for low cost processing and application to planar PICs. PMID:27451632

  14. Opportunities for Low Cost Processing of Erbium 8-Quinolinolates for Active Integrated Photonic Applications.

    PubMed

    Penna, Stefano; Mattiello, Leonardo; Di Bartolo, Silvia; Pizzoleo, Angelo; Attanasio, Vincenzo; Beleffi, Giorgio Maria Tosi; Otomo, Akira

    2016-04-01

    Erbium-doped organic emitters are promising active materials for Photonic Integrated Circuits (PICs) due to their emission shown at 1550 nm combined to the potential low cost processing. In particular, Erbium Quinoline (ErQ) gained a strong interest in the last decade for the good emission efficiency. This contribution reports the results derived from the application of ErQ as active core material within a buried optical waveguide, following the development of a purposed optical process to control the refractive index of ErQ and then to define a patterned structure from a single thin film deposition step. The reported results show the potential of Er-doped organic materials for low cost processing and application to planar PICs.

  15. Antimicrobial Activity of 8-Quinolinols, Salicylic Acids, Hydroxynaphthoic Acids, and Salts of Selected Quinolinols with Selected Hydroxy-Acids

    PubMed Central

    Gershon, Herman; Parmegiani, Raulo

    1962-01-01

    Seventy-seven compounds were screened by the disc-plate method against strains of five bacteria and five fungi. A new constant was proposed to describe the antimicrobial activity of a compound in a defined system of organisms. This constant includes not only the inhibitory level of activity of the material but also the number of organisms inhibited. This constant, the antimicrobial spectrum index, was compared with the antimicrobial index of Albert. PMID:13898066

  16. Spectrophotometric determination of metronidazole and secnidazole in pharmaceutical preparations.

    PubMed

    Saffaj, T; Charrouf, M; Abourriche, A; Abboud, Y; Bennamara, A; Berrada, M

    2004-10-01

    A rapid and sensitive spectrophotometric method is proposed for determination of metronidazole and secnidazole. The method depends on the reduction of metronidazole and secnidazole molecule with zinc dust and hydrochloric acid flowed by diazotization and coupling with 8-quinolinol to give red colored chromogens easily measured spectrophotometrically which has lambda(max) = 500 nm. The experimental conditions were optimized and Berr's law was obeyed over the applicable concentration ranges both techniques were applied successfully to a wide variety of pharmaceutical preparations. PMID:15474063

  17. Complexation and coordination selectivities of the tetradentate ligand 7-[(2-hydroxy-5-sulfophenyl) azo]-8-hydroxyquinoline-5-sulfonic acid with Fe(II), Ni(II), Zn(II), Cd(II) and VO(IV)

    SciTech Connect

    Huang, Hu; Kai, Fumiaki; Hirohata, Masaaki; Nakamura, Masaaki; Matsuzaki, Susumu; Komori, Kenji; Tsunematsu, Yuriko

    1993-12-31

    The new title tetradentate ligand (SPAHQS), containing both phenylazo and 8-quinolinol fragments, was prepared. Proton-dissociation processes of the ligand and complexing equilibria with Fe(II), Ni(II), Zn(II), Cd(II), and VO(IV) were analyzed spectrophotometrically. Coordination modes of SPAHQS with these metal ions have been investigated by means of polarography and Raman spectroscopy in aqueous solution. It was established that the coordination selectivity of SPAHQS for such metal ions is mainly dependent on steric factors in the chelate ring formed, not on HSAB properties. 18 refs., 6 figs., 2 tabs.

  18. What is the weighing form in gravimetric determination of antimony(III) with oxine?

    PubMed

    Hioki, Akiharu

    2004-03-01

    The gravimetric analysis of antimony(III) with oxine (8-quinolinol, Hox) was studied. The amount of antimony left in filtrate and washing solutions was corrected with the results of atomic absorption spectrometry. The weighing form, which had not been conclusive before the present study, was determined to be SbO(ox)(Hox)2. The result (purity of antimony(II) oxide: 99.84 +/- 0.05% (m/m)) of the gravimetric analysis was in good agreement with that of coulometric titration with electrogenerated iodine.

  19. Selective Precipitation of Thorium lodate from a Tartaric Acid-Hydrogen Peroxide Medium Application to Rapid Spectrophotometric Determination of Thorium in Silicate Rocks and in Ores

    USGS Publications Warehouse

    Grimaldi, F.S.

    1957-01-01

    This paper presents a selective iodate separation of thorium from nitric acid medium containing d-tartaric acid and hydrogen peroxide. The catalytic decomposition of hydrogen peroxide is prevented by the use of 8quinolinol. A few micrograms of thorium are separated sufficiently clean from 30 mg. of such oxides as cerium, zirconium, titanium, niobium, tantalum, scandium, or iron with one iodate precipitation to allow an accurate determination of thorium with the thoronmesotartaric acid spectrophotometric method. The method is successful for the determination of 0.001% or more of thorium dioxide in silicate rocks and for 0.01% or more in black sand, monazite, thorite, thorianite, eschynite, euxenite, and zircon.

  20. A family of tetranuclear quinolinolate Dy(iii)-based single-molecule magnets: effects of periphery ligand replacement on their magnetic relaxation.

    PubMed

    Zhang, Da; Tian, Yong-Mei; Sun, Wen-Bin; Li, Hong-Feng; Chen, Peng; Zhang, Yi-Quan; Yan, Peng-Fei

    2016-02-14

    Three complexes with formula {Dy(q)2(L)}2(μ3-OH)2{Dy(q)(L)}2(solvents) (where q = 8-quinolinolate; L = acetylacetone (acac) with (CH2Cl2)2 = solvent (1), 1,3-diphenyl-1,3-propanedione (DBM) and (CH2Cl2)2 = solvent (2), and hexafluoroacetylacetone (hfac) and CHCl3 = solvent (3)) were structurally and magnetically characterized. They have similar Dy4 structural cores bridged by N and O atoms from 8-quinolinolate, and only differ in the peripheral β-diketonate ligands. The variable-frequency and temperature alternating-current (ac) magnetic susceptibility measurements reveal that complexes 1 and 2 display significant zero-field single-molecule-magnet (SMM) behavior, while complex 3 exhibits the field-induced SMM behavior, albeit they possess the nearly same primary coordination sphere. The ac susceptibility measurement on the diluted samples verified that their relaxation was of purely molecular origin, and their distinct slow magnetic behaviors were related to the replacement of the peripheral β-diketonate ligand, which is responsible for their different individual Dy(iii) ions' magnetic anisotropy and intramolecular coupling, as confirmed by ab initio calculation.

  1. Potentiometric responses of polymeric liquid membranes based on hydrophobic chelating agents to metal ions.

    PubMed

    Itoh, Y; Ueda, Y; Hirano, A; Sugawara, M; Tohda, K; Akaiwa, H; Umezawa, Y

    2001-05-01

    The effect of hydrophobicity of acidic chelating agents as sensing materials on the potentiometric responses of polymeric liquid membranes was investigated. The chelating agents tested were 8-quinolinol (HOx), dithizone (HDz), 1-(2-pyridylazo)-2-naphthol (PAN) and their alkylated analogues, 5-octyloxymethyl-8-quinolinol (HO8Q), di(phexylphenyl)thiocarbazone (C6HDz), 7-pentadecyloxy-1-(2-pyridylazo)-2-naphthol (C15PAN) and a series of N-alkylcarbonyl-N-phenylhydroxylamines (CnPHA, n = 3, 6, 9, 12). The distribution coefficients between membrane solvent and water were determined to evaluate the hydrophobicity of the agents. The potential-pH profiles of the membranes containing hydrophobic chelating agents demonstrated the generation of potentiometric responses, while less hydrophobic agents gave no response. A possible model for the generation of membrane potential is proposed. The charge separation is attained by the permselective uptake of metal cations by the chelating agent anion at membrane/solution interface, where the high hydrophobicity of the agent enables the anionic or deprotonated form of the agents to remain at the membrane/solution interface.

  2. Structural dynamics of nitrosylruthenium isomeric complexes studied with steady-state and transient pump-probe infrared spectroscopies

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Yang, Fan; Wang, Jianru; Yu, Pengyun; Pan, Huifen; Wang, Hongfei; Wang, Jianping

    2016-09-01

    The characteristic nitrosyl stretching (NO) in the region of 1800-1900 cm- 1 was used to study the geometric and ligand effect on two nitrosylruthenium complexes, namely [Ru(OAc)(2QN)2NO] (QN = 2-chloro-8-quinolinol (H2cqn) or QN = 2-methyl-8-quinolinol (H2mqn)). The NO stretching frequency (νNO) was found in the following order: νcis-1 (2cqn) > νcis-2 (2cqn) > νcis-1 (2mqn) > νtrans (2mqn). The results exhibited a spectral sensitivity of the NO mode to both charge distribution and ligand arrangement, which was supported by ab initio computations and natural bond orbital (NBO) analyses. Further, the vibrational population of the vibrationally excited NO stretching mode was found to relax on the order of 7-10 ps, showing less than 30% variation from one isomer to another, which were explained on the basis of NO local structures and solute-solvent interactions in these isomeric nitrosylruthenium complexes.

  3. Covalent heterogenization of discrete bis(8-quinolinolato)dioxomolybdenum(VI) and dioxotungsten(VI) complexes by a metal-template/metal-exchange method: Cyclooctene epoxidation catalysts with enhanced performances

    SciTech Connect

    Yang, Ying; Chattopadhyay, Soma; Shibata, Tomohiro; Ren, Yang; Lee, Sungsik; Kan, Qiubin

    2014-10-01

    A metal-template/metal-exchange method was used to imprint covalently attached bis(8- quinolinolato)dioxomolybdenum(VI) and dioxotungsten(VI) complexes onto large surface-area, mesoporous SBA-15 silica to obtain discrete MoO2 VIT and WO2 VIT catalysts bearing different metal loadings, respectively. Homogeneous counterparts, MoO2 VIN and WO2 VIN, as well as randomly ligandgrafted heterogeneous analogues, MoO2 VIG and WO2 VIG, were also prepared for comparison. X-ray absorption fine structure (XAFS), pair distribution function (PDF) and UV–vis data demonstrate that MoO2 VIT and WO2 VIT adopt a more solution-like bis(8-quinolinol) coordination environment than MoO2 VIG and WO2 VIG, respectively. Correspondingly, the templated MoVI and WVI catalysts show superior performances to their randomly grafted counterparts and neat analogues in the epoxidation of cyclooctene. It is found that the representative MoO2 VIT-10% catalyst can be recycled up to five times without significant loss of reactivity, and heterogeneity test confirms the high stability of MoO2 VIT-10% catalyst against leaching of active species into solution. The homogeneity of the discrete bis(8-quinolinol) metal spheres templated on SBA-15 should be responsible for the superior performances.

  4. Concentration method for the spectrochemical determination of seventeen minor elements in natural water

    USGS Publications Warehouse

    Silvey, W.D.; Brennan, R.

    1962-01-01

    A method for the quantitative spectrochemical determination of microgram amounts of 17 minor elements in water is given. The chelating reagents 8-quinolinol, tannic acid, and thionalide are utilized to concentrate traces (1 to 500 ??g.) of aluminum, cobalt, chromium, copper, iron, gallium, germanium, manganese, nickel, titanium, vanadium, bismuth, lead, molybdenum, cadmium, zinc, and beryllium. Indium is added as a buffer, and palladium is used as an internal standard. The ashed oxides of these 17 metals are subsequently subjected to direct current arcing conditions during spectrum analysis. The method can be used to analyze waters with dissolved solids ranging from less than 100 to more than 100,000 p.p.m. There is no limiting concentration range for the determination of the heavy metals since any volume of sample can be used that will contain a heavy metal concentration within the analytical range of the method. Both the chemical and spectrographic procedures are described, and precision and accuracy data are given.

  5. Nonaqueous catalytic fluorometric trace determination of vanadium based on the pyronine B-hydrogen peroxide reaction and flow injection after cloud point extraction.

    PubMed

    Paleologos, E K; Koupparis, M A; Karayannis, M I; Veltsistas, P G

    2001-09-15

    The catalytic effect of vanadium on the pyronine B-H2O2 system is examined. Enhancement of the catalytic reaction rate along with the efficiency and selectivity against vanadium is achieved in a formic acid environment in the presence of a nonionic surfactant (Triton X-114). Elimination of drastic interference caused by inorganic acids and aqueous matrix along with a 50-fold preconcentration of vanadium are facilitated through cloud point extraction of its neutral complex with 8-quinolinol in an acidic solution. Subsequent flow injection analysis (FIA) with fluorometric detection renders the proposed method ideal for selective and cost-effective determination of as little as 0.020 microng L(-1) vanadium in environmental, biological, and food substrates. The preconcentration step can be applied simultaneously to multiple samples, allowing for massive preparation prior to analysis, compensating, thus, for the time-consuming procedure.

  6. Stabilized liquid membrane device (SLMD) for the passive, integrative sampling of labile metals in water

    USGS Publications Warehouse

    Brumbaugh, W.G.; Petty, J.D.; Huckins, J.N.; Manahan, S.E.

    2002-01-01

    A stabilized liquid membrane device (SLMD) is described for potential use as an in situ, passive, integrative sampler for cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in natural waters. The SLMD (patent pending) consists of a 2.5-cm-wide by 15-cm-long strip of low-density polyethylene (LDPE) layflat tubing containing 1 mL of an equal mixture (v/v) of oleic acid (cis-9-octadecenoic acid) and EMO-8Q (7-[4-ethyl-1-methyloctyl]-8-quinolinol). The reagent mixture continuously diffuses to the exterior surface of the LDPE membrane, and provides for sequestration of several divalent metals for up to several weeks. Depending on sampler configuration, concentration factors of several thousand can be realized for these metal ions after just a few days. In addition to in situ deployment, the SLMD may be useful for laboratory determination of labile metal species in grab samples. Methods for minimizing the effects of water flow on the sampling rate are currently under investigation.

  7. Photocontrolled nitric oxide release from two nitrosylruthenium isomer complexes and their potential biomedical applications

    NASA Astrophysics Data System (ADS)

    Liu, Jiao; Duan, Qingqing; Wang, Jianru; Song, Zhen; Qiao, Xiaoyan; Wang, Hongfei

    2015-01-01

    Nitric oxide (NO) has key regulatory roles in various biological and medical processes. The control of its local concentration, which is crucial for obtaining the desired effect, can be achieved with exogenous NO donors. Release of NO from metal-nitrosyl complexes upon exposure to light is a strategy that could allow for the site-specific delivery of the reactive species NO to physiological targets. The photodissociation of NO from two nitrosylruthenium(II) isomer complexes {cis- and trans-[Ru(OAc)2NO]} was demonstrated by matrix-assisted laser desorption ionization time-of-flight mass spectrometry spectra, and electron paramagnetic resonance spectra further prove the photoinduced NO release by spin trapping of NO free radicals upon photoirradiation. Real-time NO release was quantitatively measured by electrochemistry with an NO-specific electrode. The quantitative control of NO release from [Ru(OAc)2NO] in aqueous solutions was done by photoirradiation at different wavelengths. Both isomers show photoinduced damage on plasmid DNA, but the trans isomer has higher cytotoxicity and photocytotoxicity activity against the HeLa tumor cell line than that of the cis isomer. Nitrosylruthenium(II) complex, with 8-quinolinol derivatives as ligands, has a great potential as a photoactivated NO donor reagent for biomedical applications.

  8. Spectrophotometric catalytic determination of small amounts of rhenium in mineralized rocks and molybdenite

    USGS Publications Warehouse

    Simon, F.O.; Grimaldi, F.S.

    1962-01-01

    Rhenium is determined by spectrophotometry of the tellurium sol formed by the reduction of tellurate by stannous chloride under the catalytic influence of rhenium. A detailed investigation of the conditions for high sensitivity and stability at lowest concentration levels of rhenium is presented as well as the behavior of 26 ions. The method is applied to the determination of some tenths of 1 p.p.m. or more of rhenium in a 1-mg. aliquot of mineralized rocks, mixtures of molybdenite and rocks, and molybdenite concentrates. The practical quantity limit of detection is 2 ?? 10-10 gram of rhenium. Samples are decomposed with a mixture of CaO, CaCl2, and MgO. On leaching, most constituents of the sample are precipitated either as calcium salts or hydroxides, except for rhenium and a small amount of molybdenum which pass into the filtrate. Residual molybdenum is removed by extraction with 8-quinolinol in chloroform. Better than 95% recoveries are obtained with two fusions with flux.

  9. Highly efficient blue organic light-emitting diodes using quantum well-like multiple emissive layer structure

    PubMed Central

    2014-01-01

    In this study, the properties of blue organic light-emitting diodes (OLEDs), employing quantum well-like structure (QWS) that includes four different blue emissive materials of 4,4′-bis(2,2′-diphenylyinyl)-1,1′-biphenyl (DPVBi), 9,10-di(naphth-2-yl)anthracene (ADN), 2-(N,N-diphenyl-amino)-6-[4-(N,N-diphenyl amine)styryl]naphthalene (DPASN), and bis(2-methyl-8-quinolinolate)-4-(phenyl phenolato) aluminum (BAlq), were investigated. Conventional QWS blue OLEDs composed of multiple emissive layers and charge blocking layer with lower highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy level, and devices with triple emissive layers for more significant hole-electron recombination and a wider region for exciton generation were designed. The properties of triple emissive layered blue OLEDs with the structure of indium tin oxide (ITO) /N,N′-diphenyl-N,N′-bis(1-naphthyl-phenyl)-(1,1′-biphenyl)-4,4′-diamine (NPB) (700 Ǻ)/X (100 Ǻ)/BAlq (100 Ǻ)/X (100 Ǻ)/4,7-diphenyl-1,10-phenanthroline (Bphen) (300 Ǻ)/lithium quinolate (Liq) (20 Ǻ)/aluminum (Al) (1,200 Ǻ) (X = DPVBi, ADN, DPASN) were examined. HOMO-LUMO energy levels of DPVBi, ADN, DPASN, and BAlq are 2.8 to 5.9, 2.6 to 5.6, 2.3 to 5.2, and 2.9 to 5.9 eV, respectively. The OLEDs with DPASN/BAlq/DPASN QWS with maximum luminous efficiency of 5.32 cd/A was achieved at 3.5 V. PMID:24940170

  10. A Novel Method Applied in Determination and Assessment of Trace Amount of Lead and Cadmium in Rice from Four Provinces, China

    PubMed Central

    Li, Shan; Wang, Mei; Yang, Bingyi; Zhong, Yizhou; Feng, Le

    2014-01-01

    Heavy metal contamination of soils or water can lead to excessive lead (Pb) and cadmium (Cd) levels in rice. As cumulative poisons, consumption of Pb and Cd in contaminated rice may cause many toxic effects in humans. In the present study, Pb and Cd levels in rice samples from Hubei, Jiangxi, Heilongjiang, and Guangdong provinces in China were analyzed by cloud point extraction and graphite furnace atomic absorption spectrometry (GFAAS). The heavy metals in the rice samples were reacted with 8-quinolinol to form a complex at pH 9.0 and 40°C. Analytes were quantitatively extracted to a surfactant-rich phase (Triton X-45) after centrifugation and analyzed by GFAAS. The effects of experimental conditions, including pH, concentration of reagents, and equilibration time and temperature, on cloud point extraction were optimized efficiently using Plackett–Burman and Box–Behnken experimental designs. Under the optimum conditions, good linearity was observed in the concentration ranges of 0.5–5 µg/L for Pb and 0.05–0.50 µg/L for Cd. The limits of detection were 0.043 µg/L for Pb with a concentration factor of 24.2 in a 10 mL sample and 0.018 µg/L for Cd with a concentration factor of 18.4 in a 10 mL sample. Twenty rice samples from four provinces were analyzed successfully, and the mean levels of Pb and Cd in the rice were all below their maximum allowable concentrations in China. Comparing the tolerable daily intakes given by FAO/WHO with the mean estimated daily intakes; Pb and Cd mean daily intake through rice consumption were 0.84 µg/kg bw/day and 0.40 µg/kg bw/day, which were lower than the tolerable daily intakes. PMID:25251454

  11. Highly efficient blue organic light-emitting diodes using quantum well-like multiple emissive layer structure

    NASA Astrophysics Data System (ADS)

    Yoon, Ju-An; Kim, You-Hyun; Kim, Nam Ho; Yoo, Seung Il; Lee, Sang Youn; Zhu, Fu Rong; Kim, Woo Young

    2014-04-01

    In this study, the properties of blue organic light-emitting diodes (OLEDs), employing quantum well-like structure (QWS) that includes four different blue emissive materials of 4,4'-bis(2,2'-diphenylyinyl)-1,1'-biphenyl (DPVBi), 9,10-di(naphth-2-yl)anthracene (ADN), 2-( N, N-diphenyl-amino)-6-[4-( N, N-diphenyl amine)styryl]naphthalene (DPASN), and bis(2-methyl-8-quinolinolate)-4-(phenyl phenolato) aluminum (BAlq), were investigated. Conventional QWS blue OLEDs composed of multiple emissive layers and charge blocking layer with lower highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy level, and devices with triple emissive layers for more significant hole-electron recombination and a wider region for exciton generation were designed. The properties of triple emissive layered blue OLEDs with the structure of indium tin oxide (ITO) / N, N'-diphenyl- N, N'-bis(1-naphthyl-phenyl)-(1,1'-biphenyl)-4,4'-diamine (NPB) (700 Ǻ)/X (100 Ǻ)/BAlq (100 Ǻ)/X (100 Ǻ)/4,7-diphenyl-1,10-phenanthroline (Bphen) (300 Ǻ)/lithium quinolate (Liq) (20 Ǻ)/aluminum (Al) (1,200 Ǻ) (X = DPVBi, ADN, DPASN) were examined. HOMO-LUMO energy levels of DPVBi, ADN, DPASN, and BAlq are 2.8 to 5.9, 2.6 to 5.6, 2.3 to 5.2, and 2.9 to 5.9 eV, respectively. The OLEDs with DPASN/BAlq/DPASN QWS with maximum luminous efficiency of 5.32 cd/A was achieved at 3.5 V.

  12. 8-Hydroxyquinoline anchored to silica gel via new moderate size linker: synthesis and applications as a metal ion collector for their flame atomic absorption spectrometric determination.

    PubMed

    Goswami, Anupama; Singh, Ajai K; Venkataramani, B

    2003-08-29

    The silica gel modified with (3-aminopropyl-triethoxysilane) was reacted with 5-formyl-8-hydroxyquinoline (FHOQ(x)) to anchor 8-quinolinol ligand on the silica gel. It was characterised with cross polarisation magic angle spinning (CPMAS) NMR and diffuse reflectance infrared Fourier transformation (DRIFT) spectroscopy and used for the preconcentration of Cu(II), Pb(II), Ni(II), Fe(III), Cd(II), Zn(II) and Co(II) prior to their determination by flame atomic absorption spectrometry. The surface area of the modified silica gel has been found to be 227 m(2) g(-1) and the two pKa values as 3.8 and 8.0. The optimum pH ranges for quantitative sorption are 4.0-7.0, 4.5-7.0, 3.0-6.0, 5.0-8.0, 5.0-8.0, 5.0-8.0 and 4.0-7.0 for Cu, Pb, Fe, Zn, Co, Ni and Cd, respectively. All the metals can be desorbed with 2.5 mol l(-1) HCl or HNO(3). The sorption capacity for these metal ions is in range of 92-448.0 micromol g(-1) and follows the order Cd

  13. S-shaped decanuclear heterometallic [Ni8Ln2] complexes [Ln(III) = Gd, Tb, Dy and Ho]: theoretical modeling of the magnetic properties of the gadolinium analogue.

    PubMed

    Hossain, Sakiat; Das, Sourav; Chakraborty, Amit; Lloret, Francesc; Cano, Joan; Pardo, Emilio; Chandrasekhar, Vadapalli

    2014-07-14

    The reaction of 8-quinolinol-2-carboaldoxime (LH2) with Ni(II) and Ln(III) salts afforded the heterometallic decanuclear compounds [Ni8Dy2(μ3-OH)2(L)8(LH)2(H2O)6](ClO4)2·16H2O (1), [Ni8Gd2(μ3-OH)2(L)8(LH)2(H2O)4(MeOH)2](NO3)2·12H2O (2), [Ni8Ho2(μ3-OH)2(L)8(LH)2(H2O)4(MeOH)2](ClO4)2·2MeOH·12H2O (3) and [Ni8Tb2 (μ3-OH)2(L)8(LH)2(MeOH)4(OMe)2]·2CH2Cl2·8H2O (4). While compounds 1-3 are dicationic, compound 4 is neutral. These compounds possess an S-shaped architecture and comprise a long chain of metal ions bound to each other. In all the complexes, the eight Ni(II) and two Ln(III) ions of the multimetallic ensemble are hold together by two μ3-OH, eight dianionic (L(2-)) and two monoanionic oxime ligands (LH(-)) whereas compound 4 has two μ3-OH, eight dianionic (L(2-)), two monoanionic oxime ligands (LH(-)) and two terminal methoxy (MeO(-)) ligands. The central portion of the S-shaped molecular wire is made up of an octanuclear Ni(II) ensemble which has at its two ends the Ln(III) caps. Magnetic studies on 1-4 reveal that the magnetic interactions between neighboring metal ions are negligible at room temperature. On the other hand, at lower temperatures in all the compounds anti-ferromagnetic interactions seem to be dominated. Analysis of the magnetic data for the Gd(III) derivative indicates Ni(II)-Ni(II) anti-ferromagnetic interactions and Gd(III)-Ni(II) ferromagnetic interactions at low temperatures. A theoretical density functional study on the magnetic behavior of the Gd(III) derivative suggests that while the weak ferromagnetic interaction between Gd(III) and Ni(II) is in line with the expectation of the magnetic interactions between orthogonal d and f orbitals, antiferromagnetic Ni(II)-Ni(II) interactions are related to the wide Ni-O-Ni angles (∼102°) and quasi-planar conformation of the Ni2O2 core. PMID:24876072

  14. Clioquinol: review of its mechanisms of action and clinical uses in neurodegenerative disorders.

    PubMed

    Bareggi, Silvio R; Cornelli, Umberto

    2012-01-01

    Clioquinol was produced as a topical antiseptic and marketed as an oral intestinal amebicide in 1934, being used to treat a wide range of intestinal diseases. In the early 1970s, it was withdrawn from the market as an oral agent because of its association with subacute myelo-optic neuropathy (SMON), a syndrome that involves sensory and motor disturbances in the lower limbs and visual changes. The first methods for determining plasma and tissue clioquinol (5-chloro-7-iodo-8-quinolinol) levels were set up in the 1970s and involved HPLC separation with UV detection, these were followed by a more sensitive GC method with electron capture detection and a gaschromatographic-massspectrometric (GC-MS) method. Finally, an HPLC method using electrochemical detection has proved to be as highly sensitive and specific as the GC-MS. In rats, mice, rabbits, and hamsters, clioquinol is rapidily absorbed and undergoes first-pass metabolization to glucuronate and sulfate conjugates; the concentrations of the metabolites are higher than those of free clioquinol. Bioavailabilty versus intraperitoneal dosing is about 12%. Dogs and monkeys form fewer conjugates. In man, single-dose concentrations are dose related, and the drug's half-life is 11-14 h. There is no accumulation, and the drug is much less metabolized to conjugates. Clioquinol acts as a zinc and copper chelator. Metal chelation is a potential therapeutic strategy for Alzheimer's disease (AD) because zinc and copper are involved in the deposition and stabilization of amyloid plaques, and chelating agents can dissolve amyloid deposits in vitro and in vivo. In general, the ability of clioquinol to chelate and redistribute metals plays an important role in diseases characterised by Zn, Cu, Fe dyshomeostasis, such as AD and Parkinson's disease, as it reduces oxidation and the amyloid burden. Zinc chelators may also act as anticancer agents. Animal toxicity studies have revealed species-specific differences in neurotoxic responses