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Sample records for 8-hydroxyquinoline

  1. Potential levels of metal complexes of 8-hydroxyquinoline

    NASA Astrophysics Data System (ADS)

    Nishikiori, Hiromasa; Nakamura, Shogo; Natori, Daichi; Teshima, Katsuya

    2016-10-01

    The potential levels of 8-hydroxyquinoline and its titanium and zinc complexes were determined by electrochemical measurements and quantum chemical calculations. The HOMO and LUMO levels of the complexes were lower and higher than those of the iodine redox couple and titania conduction band edge, respectively. This indicated that the electrons can be transferred from the electrolyte to the titania via the complexes. The 8-hydroxyquinoline formed titanium complexes on the titania surface and formed zinc complexes in the presence of zinc ions on the surface. It is suggested that electrons were injected from the complex LUMO into the titania conduction band.

  2. Synthesis and biological activity of some 5-substituted aminomethyl-8-hydroxyquinoline-7-sulphonic acids.

    PubMed

    Yanni, A S; Mohharam, A M

    1990-01-01

    5-Aryl (or alkyl)-8-hydroxyquinoline-7-sulphonic acids have been prepared by the Mannich reaction of 8-hydroxyquinoline-7-sulphonic acid with primary and secondary amines. Their bactericidal activities have been determined.

  3. Interaction of 8-Hydroxyquinoline with Cadmium Halides in Solid State

    NASA Astrophysics Data System (ADS)

    Beg, M. A.; Ahmad, A.; Beg, Saba; Askari, Hasan

    1995-07-01

    The solid state reactions of 8-hydroxyquinoline (8-HQ) and cadmium halides (CdX2; X = Cl, Br, and I) have been studied. Each reaction follows the rate equation Xn = kt. The activation energies calculated from the progress of the reaction studied by the lateral diffusion technique are 74.55 ± 1.22, 84.65 ± 3.88, and 101.66 ± 0.93 kJ mole-1 for CdCl2-8-HQ CdBr2-8-HQ and Cdl2-8-HQ reactions, respectively. 8-HQ diffuses into cadmium halide grains by a defect mechanism; penetration to the grains is preceded by surface migration. The reactions were followed by chemical analysis, IR spectral studies, and thermal and conductivity measurements. A single addition product, [CdX2-(8-HQ)], was obtained for CdCl2 and CdBr2, whereas Cdl2 gave rise to two addition products, Cdl2-(8-HQ) and Cdl2-(8-HQ)2.

  4. The evaluation of liposome-water partitioning of 8-hydroxyquinolines and their copper complexes.

    PubMed

    Kaiser, Sibylle M; Escher, Beate I

    2006-03-15

    Bioavailability and toxicity of mixtures are urgent research issues, but usually mixtures of exclusively organic chemicals or exclusively metals are investigated. In our study, we explored the role of combinations of hydrophobic ionogenic organic compounds (HIOCs) with copper (Cu2+)for uptake and bioavailability of metals and hydrophobic metal complexes in an in vitro membrane system. We investigated the influence of the interactions of copper and 8-hydroxyquinolines, both components used in formulations of pesticides, on their partitioning into liposomes, which are model systems for biological membranes and are composed of lipid bilayers made of phosphatidylcholine. The test set of compounds comprised the parent compound 8-hydroxyquinoline and 8-hydroxyquinolines with hydrophobic (e.g., 5-chloro-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 5,7-dibromo-8-hydroxyquinoline) and with hydrophilic (e.g., 8-hydroxyquinoline-5-sulfonic acid) substituents. Hydrophobic 8-hydroxyquinolines facilitate the passive uptake of copper into phospholipid bilayers by complex formation. Not only the neutral species of the ligands and their neutral copper ligand complexes are significantly taken up into the membrane, but also the cationic and anionic species of the ligands and the cationic complexes. The neutral, anionic, and cationic species of 8-hydroxyquinoline and the hydrophobic substituted 8-hydroxyquinolines exhibit linear correlations between their logarithmic liposome-water partitioning coefficients (log Klipw) and the logarithmic octanol-water partitioning coefficients of their neutral species (log Kow, neutral). The neutral species show the strongest partitioning followed by the anionic and cationic species. The associated quantitative structure activity relationships describing the dependency of log Klipw of the various species from log Kow, neutral of the neutral ligand species have slopes between 0.9 and 1. In contrast, the partitioning of the neutral and cationic

  5. Effect of 8-hydroxyquinoline and derivatives on human neuroblastoma SH-SY5Y cells under high glucose.

    PubMed

    Suwanjang, Wilasinee; Prachayasittikul, Supaluk; Prachayasittikul, Virapong

    2016-01-01

    8-Hydroxyquinoline and derivatives exhibit multifunctional properties, including antioxidant, antineurodegenerative, anticancer, anti-inflammatory and antidiabetic activities. In biological systems, elevation of intracellular calcium can cause calpain activation, leading to cell death. Here, the effect of 8-hydroxyquinoline and derivatives (5-chloro-7-iodo-8-hydroxyquinoline or clioquinol and 8-hydroxy-5-nitroquinoline or nitroxoline) on calpain-dependent (calpain-calpastatin) pathways in human neuroblastoma (SH-SY5Y) cells was investigated. 8-Hydroxyquinoline and derivatives ameliorated high glucose toxicity in SH-SY5Y cells. The investigated compounds, particularly clioquinol, attenuated the increased expression of calpain, even under high-glucose conditions. 8-Hydroxyquinoline and derivatives thus adversely affected the promotion of neuronal cell death by high glucose via the calpain-calpastatin signaling pathways. These findings support the beneficial effects of 8-hydroxyquinolines for further therapeutic development. PMID:27635352

  6. Effect of 8-hydroxyquinoline and derivatives on human neuroblastoma SH-SY5Y cells under high glucose

    PubMed Central

    Suwanjang, Wilasinee; Prachayasittikul, Supaluk

    2016-01-01

    8-Hydroxyquinoline and derivatives exhibit multifunctional properties, including antioxidant, antineurodegenerative, anticancer, anti-inflammatory and antidiabetic activities. In biological systems, elevation of intracellular calcium can cause calpain activation, leading to cell death. Here, the effect of 8-hydroxyquinoline and derivatives (5-chloro-7-iodo-8-hydroxyquinoline or clioquinol and 8-hydroxy-5-nitroquinoline or nitroxoline) on calpain-dependent (calpain-calpastatin) pathways in human neuroblastoma (SH-SY5Y) cells was investigated. 8-Hydroxyquinoline and derivatives ameliorated high glucose toxicity in SH-SY5Y cells. The investigated compounds, particularly clioquinol, attenuated the increased expression of calpain, even under high-glucose conditions. 8-Hydroxyquinoline and derivatives thus adversely affected the promotion of neuronal cell death by high glucose via the calpain-calpastatin signaling pathways. These findings support the beneficial effects of 8-hydroxyquinolines for further therapeutic development. PMID:27635352

  7. Effect of 8-hydroxyquinoline and derivatives on human neuroblastoma SH-SY5Y cells under high glucose

    PubMed Central

    Suwanjang, Wilasinee; Prachayasittikul, Supaluk

    2016-01-01

    8-Hydroxyquinoline and derivatives exhibit multifunctional properties, including antioxidant, antineurodegenerative, anticancer, anti-inflammatory and antidiabetic activities. In biological systems, elevation of intracellular calcium can cause calpain activation, leading to cell death. Here, the effect of 8-hydroxyquinoline and derivatives (5-chloro-7-iodo-8-hydroxyquinoline or clioquinol and 8-hydroxy-5-nitroquinoline or nitroxoline) on calpain-dependent (calpain-calpastatin) pathways in human neuroblastoma (SH-SY5Y) cells was investigated. 8-Hydroxyquinoline and derivatives ameliorated high glucose toxicity in SH-SY5Y cells. The investigated compounds, particularly clioquinol, attenuated the increased expression of calpain, even under high-glucose conditions. 8-Hydroxyquinoline and derivatives thus adversely affected the promotion of neuronal cell death by high glucose via the calpain-calpastatin signaling pathways. These findings support the beneficial effects of 8-hydroxyquinolines for further therapeutic development.

  8. Structure and simulation of a Zundel ion stabilized by 8-hydroxyquinoline-5, 7 disulphonic acid

    NASA Astrophysics Data System (ADS)

    Venkatakrishnan, Hasthi Annapurna; Venkatakrishnan, Ramaseshan; Pennathur, Anuj Krishnasundar; Pennathur, Gautam

    2016-07-01

    8-hydroxyquinoline-5, 7 disulphonic was synthesized and recrystallized in methanol to strip away molecules of water. The structure of the molecule revealed that Zundel ion was stabilized in the crystal. Ab-initio molecular dynamics simulation was then carried out to understand the dynamics of proton hopping in this complex. During the course of simulation, the Zundel ion coordinates with a water molecule to form an open H7O3+ structure. This transition state structure de-solvated rapidly forming Zundel ion facilitating proton hopping in the first solvation shell. One of the sulphonic acid groups in the 5 or 7 position of the 8-hydroxyquinoline 5,7 disulphonic acid bonds with the Zundel ion favoring the proton to be transferred to the nearby water molecule through the formation of proton defects. The simulation results support the structural diffusion mechanism and that charged complex migrates through the hydrogen bond network.

  9. Catalysis by manganese (III) 8-hydroxyquinolinates of the chemiluminescent reaction of luminol with hydrogen peroxide

    SciTech Connect

    Kalinichenko, I.E.; Matveeva, E.Y.; Pilipenko, A.T.

    1985-09-01

    This paper examines the kinetics of the reaction of luminol with H/sub 2/O/sub 2/ in the presence of Mn (III) 8-hydroxyquinolinate according to the data of measurements of the chemiluminescence intensity and the yield of light in this reaction. A reaction mechanism was proposed, providing for the oxidation of luminol by complexes of Mn (IV) that are formed in the decoposition of H/sub 2/O/sub 2/.

  10. Intensity and temperature-dependent photoluminescence of tris (8-hydroxyquinoline) aluminum films

    SciTech Connect

    Ajward, A. M.; Wang, X.; Wagner, H. P.

    2013-12-04

    We investigate the recombination of excitons in tris (8-hydroxyquinoline) aluminum films by intensity and temperature dependent time-resolved photoluminescence (PL). At low temperature (15 K) and elevated excitation intensity the radiative emission is quenched by singlet-singlet annihilation processes. With rising temperature the PL quenching is strongly reduced resulting in a PL efficiency maximum at ∼170 K. The reduced exciton annihilation is attributed to thermally activated occupation of non-quenchable trapped exciton states. Above 170 K the PL efficiency decreases due to thermal de-trapping of radiative states and subsequent migration to non-radiative centers.

  11. 8-Hydroxyquinolines: a review of their metal chelating properties and medicinal applications

    PubMed Central

    Prachayasittikul, Veda; Prachayasittikul, Supaluk; Ruchirawat, Somsak; Prachayasittikul, Virapong

    2013-01-01

    Metal ions play an important role in biological processes and in metal homeostasis. Metal imbalance is the leading cause for many neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis. 8-Hydroxyquinoline (8HQ) is a small planar molecule with a lipophilic effect and a metal chelating ability. As a result, 8HQ and its derivatives hold medicinal properties such as antineurodegenerative, anticancer, antioxidant, antimicrobial, anti-inflammatory, and antidiabetic activities. Herein, diverse bioactivities of 8HQ and newly synthesized 8HQ-based compounds are discussed together with their mechanisms of actions and structure–activity relationships. PMID:24115839

  12. 8-Hydroxyquinolines: a review of their metal chelating properties and medicinal applications.

    PubMed

    Prachayasittikul, Veda; Prachayasittikul, Supaluk; Ruchirawat, Somsak; Prachayasittikul, Virapong

    2013-01-01

    Metal ions play an important role in biological processes and in metal homeostasis. Metal imbalance is the leading cause for many neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and multiple sclerosis. 8-Hydroxyquinoline (8HQ) is a small planar molecule with a lipophilic effect and a metal chelating ability. As a result, 8HQ and its derivatives hold medicinal properties such as antineurodegenerative, anticancer, antioxidant, antimicrobial, anti-inflammatory, and antidiabetic activities. Herein, diverse bioactivities of 8HQ and newly synthesized 8HQ-based compounds are discussed together with their mechanisms of actions and structure-activity relationships.

  13. Electrochemiluminescence of tris(8-hydroxyquinoline-5-sulfonic acid)aluminum(III) in aqueous solution.

    PubMed

    Muegge, Brian D; Brooks, Sean; Richter, Mark M

    2003-03-01

    The electrochemiluminescence (ECL) of tris(8-hydroxyquinoline-5-sulfonic acid)aluminum(III) in aqueous solution is reported. ECL is generated by complexing aluminum ions with the chelating agent 8-hydroxyquinoline-5-sulfonic acid (HQS) to form Al(HQS)3, followed by oxidation in the presence of tri-n-propylamine (TPrA). The ECL intensity peaks a potential corresponding to oxidation of both TPrA and Al(HQS)3, and the ECL emission spectrum (lambda(max) = 499 nm) matches the photoluminescence emission spectrum, indicating that the emission is from a Al(HQS)3* excited state. ECL efficiencies (phi(ecl), photons generated per redox event) of 0.002 using Ru(bpy)3(2+) (phi(ecl) = 1) as relative standard. Conditions for ECL emission were optimized and used to generate a calibration curve that was linear over the 7 x 10(-6)-4 x 10(-4) M (5-281 mg/L (ppm)) range with a theoretical limit of detection of 1 ppm. The ECL of several metal ions other than aluminum with HQS and effects on Al(HQS)3 ECL were also examined.

  14. Understanding M-ligand bonding and mer-/fac-isomerism in tris(8-hydroxyquinolinate) metallic complexes.

    PubMed

    Lima, Carlos F R A C; Taveira, Ricardo J S; Costa, José C S; Fernandes, Ana M; Melo, André; Silva, Artur M S; Santos, Luís M N B F

    2016-06-28

    Tris(8-hydroxyquinolinate) metallic complexes, Mq3, are one of the most important classes of organic semiconductor materials. Herein, the nature of the chemical bond in Mq3 complexes and its implications on their molecular properties were investigated by a combined experimental and computational approach. Various Mq3 complexes, resulting from the alteration of the metal and substitution of the 8-hydroxyquinoline ligand in different positions, were prepared. The mer-/fac-isomerism in Mq3 was explored by FTIR and NMR spectroscopy, evidencing that, irrespective of the substituent, mer- and fac-are the most stable molecular configurations of Al(iii) and In(iii) complexes, respectively. The relative M-ligand bond dissociation energies were evaluated experimentally by electrospray ionization tandem mass spectrometry (ESI-MS-MS), showing a non-monotonous variation along the group (Al > In > Ga). The results reveal a strong covalent character in M-ligand bonding, which allows for through-ligand electron delocalization, and explain the preferred molecular structures of Mq3 complexes as resulting from the interplay between bonding and steric factors. The mer-isomer reduces intraligand repulsions, being preferred for smaller metals, while the fac-isomer is favoured for larger metals where stronger covalent M-ligand bonds can be formed due to more extensive through-ligand conjugation mediated by metal "d" orbitals. PMID:27273193

  15. Understanding M-ligand bonding and mer-/fac-isomerism in tris(8-hydroxyquinolinate) metallic complexes.

    PubMed

    Lima, Carlos F R A C; Taveira, Ricardo J S; Costa, José C S; Fernandes, Ana M; Melo, André; Silva, Artur M S; Santos, Luís M N B F

    2016-06-28

    Tris(8-hydroxyquinolinate) metallic complexes, Mq3, are one of the most important classes of organic semiconductor materials. Herein, the nature of the chemical bond in Mq3 complexes and its implications on their molecular properties were investigated by a combined experimental and computational approach. Various Mq3 complexes, resulting from the alteration of the metal and substitution of the 8-hydroxyquinoline ligand in different positions, were prepared. The mer-/fac-isomerism in Mq3 was explored by FTIR and NMR spectroscopy, evidencing that, irrespective of the substituent, mer- and fac-are the most stable molecular configurations of Al(iii) and In(iii) complexes, respectively. The relative M-ligand bond dissociation energies were evaluated experimentally by electrospray ionization tandem mass spectrometry (ESI-MS-MS), showing a non-monotonous variation along the group (Al > In > Ga). The results reveal a strong covalent character in M-ligand bonding, which allows for through-ligand electron delocalization, and explain the preferred molecular structures of Mq3 complexes as resulting from the interplay between bonding and steric factors. The mer-isomer reduces intraligand repulsions, being preferred for smaller metals, while the fac-isomer is favoured for larger metals where stronger covalent M-ligand bonds can be formed due to more extensive through-ligand conjugation mediated by metal "d" orbitals.

  16. Multifunctional 8-hydroxyquinoline-appended cyclodextrins as new inhibitors of metal-induced protein aggregation.

    PubMed

    Oliveri, Valentina; Attanasio, Francesco; Puglisi, Antonino; Spencer, John; Sgarlata, Carmelo; Vecchio, Graziella

    2014-07-14

    Mounting evidence suggests a pivotal role of metal imbalances in protein misfolding and amyloid diseases. As such, metal ions represent a promising therapeutic target. In this context, the synthesis of chelators that also contain complementary functionalities to combat the multifactorial nature of neurodegenerative diseases is a highly topical issue. We report two new 8-hydroxyquinoline-appended cyclodextrins and highlight their multifunctional properties, including their Cu(II) and Zn(II) binding abilities, and capacity to act as antioxidants and metal-induced antiaggregants. In particular, the latter property has been applied in the development of an effective assay that exploits the formation of amyloid fibrils when β-lactoglobulin A is heated in the presence of metal ions.

  17. Fluorescence quenching determination of metallothioneins using 8-hydroxyquinoline-5-sulphonic acid-Cd(II) chelate.

    PubMed

    Qian, Qiu-Mei; Wang, Yong-Sheng; Zhou, Bin; Xue, Jin-Hua; Li, Le; Wang, Yong-Song; Wang, Jia-Cheng; Yin, Ji-Cheng; Liu, Shan-Du; Zhao, Hui; Liu, Hui

    2014-01-24

    A novel method for the determination of metallothioneins (MTs) in urine was developed by fluorescence quenching strategy. The response signals linearly correlated with the concentration of MTs in the ranges of 3.12×10(-8)-1.23×10(-6) mol L(-1), and the limit of detection (LOD) was 9.36×10(-9) mol L(-1). The proposed method avoids the label and derivatization steps in common methods, and is reliable, inexpensive and sensitive. Furthermore, the interaction of MTs and 8-hydroxyquinoline-5-sulphonic acid (HQS)-Cd(II) chelate was investigated, and a static quenching mode was proposed to be primarily responsible for the fluorescence quenching event. It could provide a promising potential for the detection of the biomacromolecules which have no native fluorescence, and be benefit to extend the application of fluorescence strategy.

  18. Structure-based design, synthesis, and SAR evaluation of a new series of 8-hydroxyquinolines as HIF-1alpha prolyl hydroxylase inhibitors.

    PubMed

    Warshakoon, Namal C; Wu, Shengde; Boyer, Angelique; Kawamoto, Richard; Sheville, Justin; Renock, Sean; Xu, Kevin; Pokross, Matthew; Zhou, Songtao; Winter, Carol; Walter, Richard; Mekel, Marlene; Evdokimov, Artem G

    2006-11-01

    A new series of potent 8-hydroxyquinolines was designed based on the newly resolved X-ray crystal structure of EGLN-1. Both alkyl and aryl 8-hydroxyquinoline-7-carboxyamides were good HIF-1alpha prolyl hydroxylase (EGLN) inhibitors. In subsequent VEGF induction assays, these exhibited potent VEGF activity. In addition, this class of compounds did show the ability to stabilize HIF-1alpha.

  19. Investigation of aromatase inhibitory activity of metal complexes of 8-hydroxyquinoline and uracil derivatives

    PubMed Central

    Prachayasittikul, Veda; Pingaew, Ratchanok; Nantasenamat, Chanin; Prachayasittikul, Supaluk; Ruchirawat, Somsak; Prachayasittikul, Virapong

    2014-01-01

    Purpose Estrogens play important roles in the pathogenesis and progression of breast cancer as well as estrogen-related diseases. Aromatase is a key enzyme in the rate-limiting step of estrogen production, in which its inhibition is one strategy for controlling estrogen levels to improve prognosis of estrogen-related cancers and diseases. Herein, a series of metal (Mn, Cu, and Ni) complexes of 8-hydroxyquinoline (8HQ) and uracil derivatives (4–9) were investigated for their aromatase inhibitory and cytotoxic activities. Methods The aromatase inhibition assay was performed according to a Gentest™ kit using CYP19 enzyme, wherein ketoconazole and letrozole were used as reference drugs. The cytotoxicity was tested on normal embryonic lung cells (MRC-5) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results Only Cu complexes (6 and 9) exhibited aromatase inhibitory effect with IC50 0.30 and 1.7 μM, respectively. Cytotoxicity test against MRC-5 cells showed that Mn and Cu complexes (5 and 6), as well as free ligand 8HQ, exhibited activity with IC50 range 0.74–6.27 μM. Conclusion Cu complexes (6 and 9) were found to act as a novel class of aromatase inhibitor. Our findings suggest that these 8HQ–Cu–uracil complexes are promising agents that could be potentially developed as a selective anticancer agent for breast cancer and other estrogen-related diseases. PMID:25152615

  20. Ring-substituted 8-hydroxyquinoline-2-carboxanilides as photosystem II inhibitors.

    PubMed

    Jampilek, Josef; Kralova, Katarina; Pesko, Matus; Kos, Jiri

    2016-08-15

    Ring-substituted 8-hydroxyquinoline-2-carboxanilides inhibited photosynthetic electron transport (PET) through photosystem (PS) II. Their inhibitory efficiency depended on the compound lipophilicity, the electronic properties of the substituent R and the position of the substituent R on the benzene ring. The most effective inhibitors showing IC50 values in the range 2.3-3.6μM were substituted in C'(3) by F, CH3, Cl and Br. The dependence of the PET-inhibiting activity on the lipophilicity of the compounds was quasi-parabolic for 3-substituted derivatives, while for C'(2) ones a slight increase and for C'(4) derivatives a sharp decrease of the activity were observed with increasing lipophilicity. In addition, the dependence of PET-inhibiting activity on electronic Hammett's σ parameter of the substituent R was observed with optimum σ value 0.06 for C'(4) and 0.34 for C'(3) substituted derivatives, while the value of σ parameter did not significantly influence the PET-inhibiting activity of C'(2) substituted compounds. Interactions of the studied compounds with chlorophyll a and aromatic amino acids present in the pigment-protein complexes mainly in PS II were documented by fluorescence spectroscopy. The section between P680 and plastoquinone QB occurring on the acceptor side of PS II can be suggested as the site of action of the compounds. PMID:27432762

  1. Fluorescent complexes of nucleic acids/8-hydroxyquinoline/lanthanum(III) and the fluorometry of nucleic acids

    SciTech Connect

    Cheng Zhi Huang; Ke An Li; Shen Yang Tong

    1996-07-01

    The ternary fluorescent complexes of nucleic acids/8-hydroxyquinoline/lanthanum (III) were studied. Nucleic acids in the study involve natured and thermally denatured calf thymus DNA, fish sperm DNA and yeast RNA. In the range of PH 8.0-8.4 (controlled by NH{sub 3}-NH{sub 4}Cl buffer) ternary fluorescent complexes are formed which emit at 485.0 nm for calf thymus DNA and at 480.0 nm for fish sperm DNA when excited at 265.0 nm. Based on the fluorescence reactions sensitive fluorometric methods for nucleic acids were proposed. Using optimal conditions, the calibration curves were linear in the range of 0.4 --3.6 {mu}g{sup .}ml{sup -1} for calf thymus DNA, 0.4 -- 4.0 {mu}g{sup .}ml{sup -1} for fish sperm DNA and 0.4 --4.0{mu}g{sup .}ml{sup -1} for yeast RNA, respectively. Five synthetic samples were determined with satisfaction.

  2. Self-assembly of 2-aldehyde-8-hydroxyquinolinate-based lanthanide complexes and NIR luminescence

    NASA Astrophysics Data System (ADS)

    Zhang, Meiqi; Li, Hongfeng; Chen, Peng; Sun, Wenbin; Zhang, Lei; Yan, Pengfei

    2015-02-01

    Self-assembly reaction of 2-aldehyde-8-hydroxyquinoline, tris(hydroxymethyl)aminomethane and LnCl3ṡ6H2O affords a series of mononuclear lanthanide complexes Ce(baho)2·Et2O (1) (H2baho = 2,8-bis(2-(8-hydroxylquinolinyl))-1-aza-5-hydroxymethyl-3,7-dioxabicyclo[3.3.0]octane), Dy(nhm)2Cl·0.5H2O (2) and Ln(nhm)2Cl·0.5C6H14 (Ln = Ho (3), Er (4), Yb (5) and Hnhm = N-(2-(8-hydroxylquinolinyl)methylene)(trishydroxymethyl)methylamine. The crystal structures have been determined by X-ray crystallographic analysis, and the tetravalence of Ce in 1 has been proven by XPS. Interestingly, the positive charge of Ce4+ ion in 1 is neutralized by two deprotonated baho2- ligands, while two deprotonated nhm- ligands and one Cl- compensate the positive charge of Ln3+ ions in 2-5. Complex 5 exhibit essential NIR luminescence of Yb3+ ion with lifetime of 17.64 μs in solid and 9.96 μs in CH3OH solution.

  3. Five 8-hydroxyquinolinate-based coordination polymers with tunable structures and photoluminescent properties for sensing nitroaromatics.

    PubMed

    Zhang, Liyan; Sun, Liying; Li, Xinyuan; Tian, Yulan; Yuan, Guozan

    2015-01-01

    Using two 8-hydroxyquinolinate ligands (L1-MOM and L2-MOM) containing 3-pyridyl or 4-pyridyl groups, five novel coordination polymers, namely, [Zn3(L1)6] (1), [Zn(L1)2]·2MeOH (2), [Zn(L2)2] (3), [Cd(L2)2] (4), and [Cd4(L1)6]·13H2O (5), were synthesized and characterized by a variety of techniques. Single-crystal X-ray structures have revealed that these coordination polymers exhibit a structural diversification due to the different choices of metal salts and the effect of pyridyl nitrogen position. Compounds 1-5 exhibited different fluorescence emissions and lifetimes upon excitation in the solid state. The sensing behavior of these polymers was also investigated upon exposure to vapors of various nitroaromatic molecules (analytes). The results show that all five polymers are capable of sensing these nitroaromatic molecules in the vapor phase through fluorescence quenching. Interestingly, 3 exhibits superior sensitivity to the analytes in comparison with other polymers. 2-Nitrotoluene quenches the emission of 3 by as much as 96%.

  4. Synthesis and electroluminescence properties of tris-[5-choloro-8-hydroxyquinoline] aluminum Al(5-Clq)3

    NASA Astrophysics Data System (ADS)

    Kumar, Rahul; Bhargava, Parag; Srivastava, Ritu; Tyagi, Priyanka

    2015-06-01

    A new electroluminescent material tris-[5-choloro-8-hydroxyquinoline] aluminum has been synthesized and characterized. Solution of this material Al(5-Clq)3 in toluene showed absorption maxima at 385 nm which was attributed to the moderate energy (π-π*) transitions of the aromatic rings. The photoluminescence spectrum of Al(5-Clq)3 in toluene solution showed a peak at 522 nm. This material shows thermal stability up to 400 °C. The structure of the device is ITO/0.4 wt%F4-TCNQ doped α-NPD (35 nm) / Al(5-Clq)3 (30 nm) / BCP (6 nm) / Alq3 (30 nm) / LiF (1 nm) / Al (150 nm). This device exhibited a luminescence peak at 585 nm (CIE coordinates, x = 0.39, y = 0.50). The maximum luminescence of the device was 920 Cd/m2 at 25 V. The maximum current efficiency of OLED was 0.27 Cd/A at 20 V and maximum power efficiency was 0.04 lm/W at 18 V.

  5. Quantitative High-Throughput Screening Identifies 8-Hydroxyquinolines as Cell-Active Histone Demethylase Inhibitors

    PubMed Central

    Kawamura, Akane; Rose, Nathan R.; Ng, Stanley S.; Quinn, Amy M.; Rai, Ganesha; Mott, Bryan T.; Beswick, Paul; Klose, Robert J.; Oppermann, Udo; Jadhav, Ajit; Heightman, Tom D.; Maloney, David J.; Schofield, Christopher J.; Simeonov, Anton

    2010-01-01

    Background Small molecule modulators of epigenetic processes are currently sought as basic probes for biochemical mechanisms, and as starting points for development of therapeutic agents. Nε-Methylation of lysine residues on histone tails is one of a number of post-translational modifications that together enable transcriptional regulation. Histone lysine demethylases antagonize the action of histone methyltransferases in a site- and methylation state-specific manner. Nε-Methyllysine demethylases that use 2-oxoglutarate as co-factor are associated with diverse human diseases, including cancer, inflammation and X-linked mental retardation; they are proposed as targets for the therapeutic modulation of transcription. There are few reports on the identification of templates that are amenable to development as potent inhibitors in vivo and large diverse collections have yet to be exploited for the discovery of demethylase inhibitors. Principal Findings High-throughput screening of a ∼236,000-member collection of diverse molecules arrayed as dilution series was used to identify inhibitors of the JMJD2 (KDM4) family of 2-oxoglutarate-dependent histone demethylases. Initial screening hits were prioritized by a combination of cheminformatics, counterscreening using a coupled assay enzyme, and orthogonal confirmatory detection of inhibition by mass spectrometric assays. Follow-up studies were carried out on one of the series identified, 8-hydroxyquinolines, which were shown by crystallographic analyses to inhibit by binding to the active site Fe(II) and to modulate demethylation at the H3K9 locus in a cell-based assay. Conclusions These studies demonstrate that diverse compound screening can yield novel inhibitors of 2OG dependent histone demethylases and provide starting points for the development of potent and selective agents to interrogate epigenetic regulation. PMID:21124847

  6. Energy transfer ultraviolet photodetector with 8-hydroxyquinoline derivative-metal complexes as acceptors

    NASA Astrophysics Data System (ADS)

    Wu, Shuang-Hong; Li, Wen-Lian; Chen, Zhi; Li, Shi-Bin; Wang, Xiao-Hui; Wei, Xiong-Bang

    2015-02-01

    We choose 8-hydroxyquinoline derivative-metal complexes (Beq, Mgq, and Znq) as the acceptors (A) and 4,4',4”-tri-(2-methylphenyl phenylamino) triphenylaine (m-MTDATA) as the donor (D) respectively to study the existing energy transfer process in the organic ultraviolet (UV) photodetector (PD), which has an important influence on the sensitivity of PDs. The energy transfer process from D to A without exciplex formation is discussed, differing from the working mechanism of previous PDs with Gaq [Zisheng Su, Wenlian Li, Bei Chu, Tianle Li, Jianzhuo Zhu, Guang Zhang, Fei Yan, Xiao Li, Yiren Chen and Chun-Sing Lee 2008 Appl. Phys. Lett. 93 103309)] and REq [J. B. Wang, W. L. Li, B. Chu, L. L. Chen, G. Zhang, Z. S. Su, Y. R. Chen, D. F. Yang, J. Z. Zhu, S. H. Wu, F. Yan, H. H. Liu, C. S. Lee 2010 Org. Electron. 11 1301] used as an A material. Under 365-nm UV irradiation with an intensity of 1.2 mW/cm2, the m-MTDATA:Beq blend device with a weight ratio of 1:1 shows a response of 192 mA/W with a detectivity of 6.5× 1011 Jones, which exceeds those of PDs based on Mgq (146 mA/W) and Znq (182 mA/W) due to better energy level alignment between m-MTDATA/Beq and lower radiative decay. More photophysics processes of the PDs involved are discussed in detail. Project supported by the National Natural Science Foundation of China (Grant Nos. 61371046, 61405026, 61474016, and 61421002) and China Postdoctoral Science Foundation (Grant No. 2014M552330).

  7. Antimicrobial Activity of Metal & Metal Oxide Nanoparticles Interfaced With Ligand Complexes Of 8-Hydroxyquinoline And α-Amino Acids

    NASA Astrophysics Data System (ADS)

    Bhanjana, Gaurav; Kumar, Neeraj; Thakur, Rajesh; Dilbaghi, Neeraj; Kumar, Sandeep

    2011-12-01

    Antimicrobial nanotechnology is a recent addition to the fight against disease causing organisms, replacing heavy metals and toxins. In the present work, mixed ligand complexes of metals like zinc, silver etc. and metal oxide have been synthesized using 8-hydroxyquinoline (HQ) as a primary ligand and N-and/O-donor amino acids such as L-serine, L-alanine, glycine, cysteine and histidine as secondary ligands. These complexes were characterized using different spectroscopic techniques. The complexes were tested for antifungal and antibacterial activity by using agar well diffusion bioassay.

  8. Theoretical determination of the p Kas of the 8-hydroxyquinoline-5-sulfonic acid: A DFT based approach

    NASA Astrophysics Data System (ADS)

    Le Bahers, Tangui; Adamo, Carlo; Ciofini, Ilaria

    2009-04-01

    The three acid dissociation constants (p Kas) of the 8-hydroxyquinoline-5-sulfonic acid were computed using a computational protocol based on Density Functional Theory. A hybrid exchange correlation functional was applied and bulk solvent effects were treated within the framework of the Polarizable Continuum Model. Direct solute-solvent interactions were taken into account adding explicit water molecules. The computed p Kas are in line with the experimental data and allow better defining the first p Ka, confirmed to be negative. From the calculated p Kas, 'ab initio' distribution diagrams of the relative concentration of the different species in solution as a function of pH were drawn.

  9. Studies on the growth, structural, optical, mechanical properties of 8-hydroxyquinoline single crystal by vertical Bridgman technique

    SciTech Connect

    Prabhakaran, SP.; Babu, R. Ramesh; Velusamy, P.; Ramamurthi, K.

    2011-11-15

    Highlights: {yields} Growth of bulk single crystal of 8-hydroxyquinoline (8-HQ) by vertical Bridgman technique for the first time. {yields} The crystalline perfection is reasonably good. {yields} The photoluminescence spectrum shows that the material is suitable for blue light emission. -- Abstract: Single crystal of organic nonlinear optical material, 8-hydroxyquinoline (8-HQ) of dimension 52 mm (length) x 12 mm (dia.) was grown from melt using vertical Bridgman technique. The crystal system of the material was confirmed by powder X-ray diffraction analysis. The crystalline perfection of the grown crystal was examined by high-resolution X-ray diffraction study. Low angular spread around 400'' of the diffraction curve and the low full width half maximum values show that the crystalline perfection is reasonably good. The recorded photoluminescence spectrum shows that the material is suitable for blue light emission. Optical transmittance for the UV and visible region was measured and mechanical strength was estimated from Vicker's microhardness test along the growth face of the grown crystal.

  10. Comparative solution equilibrium studies of anticancer gallium(III) complexes of 8-hydroxyquinoline and hydroxy(thio)pyrone ligands.

    PubMed

    Enyedy, Éva A; Dömötör, Orsolya; Varga, Erika; Kiss, Tamás; Trondl, Robert; Hartinger, Christian G; Keppler, Bernhard K

    2012-12-01

    The stoichiometry and stability constants of the Ga(III) complexes of 8-hydroxyquinoline (HQ), 8-hydroxyquinoline-5-sulfonate (HQS), maltol, thiomaltol, allomaltol and thioallomaltol were determined by means of pH-potentiometry, UV-vis spectrophotometry, spectrofluorometry and (1)H NMR spectroscopy in aqueous solution. Spectrofluorometry was used to determine the stability constants of the Ga(III)-HQ species in water. Formation of [GaL](2+), [GaL(2)](+) and [GaL(3)] complexes was found and the Ga(III) binding ability of the ligands followed the order: thioallomaltol

  11. Modulating the near-infrared luminescence of neodymium and ytterbium complexes with tridentate ligands based on benzoxazole-substituted 8-hydroxyquinolines.

    PubMed

    Shavaleev, Nail M; Scopelliti, Rosario; Gumy, Frédéric; Bünzli, Jean-Claude G

    2009-04-01

    An improved synthesis of 2-(2'-benzothiazole)- and 2-(2'-benzoxazole)-8-hydroxyquinoline ligands that combine a tridentate N,N,O-chelating unit for metal binding and extended chromophore for light harvesting is developed. The 2-(2'-benzoxazole)-8-hydroxyquinoline ligands form mononuclear nine-coordinate complexes with neodymium, [Nd(kappa(3)-ligand)(3)], and an eight-coordinate complex with ytterbium, [Yb(kappa(3)-ligand)(2) x (kappa(1)-ligand) x H(2)O], as verified by crystallographic characterization of five complexes with four different ligands. The chemical stability of the complexes increases when the ligand contains 5,7-dihalo-8-hydroxyquinoline versus an 8-hydroxyquinoline group. The complexes feature a ligand-centered visible absorption band with a maximum at 508-527 nm and an intensity of (7.5-9.6) x 10(3) M(-1) x cm(-1). Upon excitation with UV and visible light within ligand absorption transitions, the complexes display characteristic lanthanide luminescence in the near-infrared at 850-1450 nm with quantum yields and lifetimes in the solid state at room temperature as high as 0.33% and 1.88 micros, respectively. The lanthanide luminescence in the complexes is enhanced upon halogenation of the 5,7-positions in the 8-hydroxyquinoline group and upon the addition of electron-donating substituents to the benzoxazole ring. Facile modification of chromophore units in 2-(2'-benzoxazole)-8-hydroxyquinoline ligands provides means for controlling the luminescence properties of their lanthanide complexes.

  12. Photoluminescence properties of new Zn(II) complexes with 8-hydroxyquinoline ligands: Dependence on volume and electronic effect of substituents

    NASA Astrophysics Data System (ADS)

    Huo, Yanping; Lu, Jiguo; Hu, Sheng; Zhang, Liming; Zhao, Fenghua; Huang, Huarong; Huang, Baohua; Zhang, Li

    2015-03-01

    A series of 2-arylethenyl-8-hydroxyquinoline ligands (A1-A4) with a trimethoxyphenyl, naphthyl, 2-fluoro-4-bromophenyl and anthracenyl group and their corresponding Zn(II) complexes (B1-B4) were synthesized and characterized by means of 1H NMR, ESI-MS, FT-IR and elemental analysis. A1 and A4 were characterized by single-crystal X-ray crystallography. The aggregation behavior of zinc salt and ligands in solution was investigated by several techniques, containing 1H NMR, UV-vis and photoluminescence (PL). The electronic nature and volume of arylethenyl substituents affect the absorption wavelength, the emission color, fluorescence lifetime, fluorescence quantum yield and thermostability of Zn(II) complexes. The experiments corroborated that the properties of Zinc(II) complexes can be tuned by introducing different functional substituents.

  13. Adsorption of lead (II) ions onto novel cassava starch 5-choloromethyl-8-hydroxyquinoline polymer from an aqueous medium.

    PubMed

    Shah, Prapti U; Raval, Nirav P; Vekariya, Mayur; Wadhwani, Poonam M; Shah, Nisha K

    2016-01-01

    Adsorption of lead (II) ions onto cassava starch 5-choloromethyl-8-hydroxyquinoline polymer (CSCMQ) was investigated with the variation in the parameters of pH, contact time, lead (II) ions concentration, temperature and the adsorbent dose. The Langmuir and Freundlich models have been applied. CSCMQ was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Results showed that the adsorption process was better described by the Langmuir model. Adsorption kinetics data obtained for the metal ions sorption were investigated using pseudo-first-order, pseudo-second-order and intraparticle diffusion model. The maximum adsorption capacities (qm) were 46.512, 43.859 and 42.735 mg/g at 25, 35 and 45 °C, respectively. The dynamical data fit well with the second-order kinetics model. The results indicate that CSCMQ could be employed as low-cost material for the adsorption of Pb(II) ions from aqueous medium. PMID:27533869

  14. Selective detection of 2,4,6-trinitrophenol based on a fluorescent nanoscale bis(8-hydroxyquinoline) metal complex.

    PubMed

    Lv, Xiao-Jun; Qi, Liang; Gao, Xiang-Yu; Wang, Huan; Huo, Yuan; Zhang, Zhi-Qi

    2016-04-01

    The reliable and accurate detection of explosives such as 2,4,6-trinitrophenol (TNP) and 2,4,6-trinitrotoluene (TNT) is in high demand for homeland security and public safety. Although extremely high sensitivity towards TNT has been demonstrated, detection of TNP remains a challenge. In this work, a fluorescent nanoscale complex composed of bis(8-hydroxyquinoline) and Al(3+) ions has been prepared, characterized and applied in detection of TNP. This complex exhibits the ability to sense the nitro explosive TNP via a fluorescence quenching mechanism with high selectivity. A simple paper test system for the rapid monitoring of TNP was also investigated. The results show that Bhq-Al is a quite ideal sensing material for trace-level detection of TNP. PMID:26838414

  15. An Introduction to Multivariate Curve Resolution-Alternating Least Squares: Spectrophotometric Study of the Acid-Base Equilibria of 8-Hydroxyquinoline-5-Sulfonic Acid

    ERIC Educational Resources Information Center

    Rodriguez-Rodriguez, Cristina; Amigo, Jose Manuel; Coello, Jordi; Maspoch, Santiago

    2007-01-01

    A spectrophotometric study of the acid-base equilibria of 8-hydroxyquinoline-5-sulfonic acid to describe the multivariate curve resolution-alternating least squares algorithm (MCR-ALS) is described. The algorithm provides a lot of information and hence is of great importance for the chemometrics research.

  16. Novel method for rapid copper chelation assessment confirmed low affinity of D-penicillamine for copper in comparison with trientine and 8-hydroxyquinolines.

    PubMed

    Říha, Michal; Karlíčková, Jana; Filipský, Tomáš; Macáková, Kateřina; Hrdina, Radomír; Mladěnka, Přemysl

    2013-06-01

    Copper is an essential trace element involved in many physiological processes. Since disorder of copper homeostasis is observed in various pathologies, copper chelators may represent a promising therapeutic tool. This study was aimed at: 1) formation of an in vitro methodology for screening of copper chelators, and 2) detailed analysis of the interaction of copper with clinically used D-penicillamine (D-PEN), triethylenetetramine (trientine), experimentally tested 8-hydroxyquinolines, and the disodium salt of EDTA as a standard chelator. Methodology based on bathocuproinedisulfonic acid disodium salt (BCS), usable at (patho)physiologically relevant pHs (4.5-7.5), enabled assessment of both cuprous and cupric ions chelation and comparison of the relative affinities of the tested compounds for copper. In the case of potent chelators, the stoichiometry could be estimated too. Clioquinol, chloroxine and EDTA formed very stable complexes with Cu(+)/Cu(2+) at all tested pHs, while copper complexes with trientine were stable only under neutral or slightly acidic conditions. Non-substituted 8-hydroxyquinoline was a less efficient copper chelator, but still unequivocally more potent than D-PEN. Both 8-hydroxyquinoline and D-PEN chelation potencies, similarly to that of trientine, were pH-dependent and decreased with pH. Moreover, only D-PEN was able to reduce cupric ions. Conclusively, BCS assay represents a rapid, simple and precise method for copper chelation measurement. In addition, lower binding affinity of D-PEN compared with 8-hydroxyquinolines and trientine was demonstrated.

  17. First-Principles study of tris(8-hydroxyquinoline)iron(III) molecules: A promising spin filter material

    NASA Astrophysics Data System (ADS)

    Jiang, Wei; Zhou, Miao; Liu, Zheng; Sun, Dali; Vardeny, Z. Valy; Liu, Feng; Feng Liu's Group Team; Z. Valy. Vardeny's Group Team

    2015-03-01

    Using first-principles calculations, we have systematically investigated the structural, electronic, and magnetic properties of facial and meridional tris (8-hydroxyquinoline)iron(III) (Feq3) molecules, solvent-free Feq3 crystals and thin films. Our calculation results show that both Feq3 isomers have a high spin state of 5 μB as the ground state when an on-site Hubbard-U term is included to treat the highly localized Fe 3 d electrons, in agreement with experiment, while the standard DFT calculations produce a low spin Fe state of 1 μB. Furthermore, the freestanding Feq3 films are found to be paramagnetic, but become Ferromagnetic (FM) within each layer when deposited on a NiFe substrate. This is induced by a strong anti-ferromagnetic (AFM) coupling between the first molecular layer and FM substrate. Also, an AFM coupling is found between the molecular layers. These findings suggest that Feq3 molecular films may serve as a promising spin filter material in spintronic devices. This work is supported by National Science Foundation-Materials Research, Science & Engineering Center (NSF-MRSEC Grant # DMR-1121252).

  18. Indium-tin-oxide-free tris(8-hydroxyquinoline) Al organic light-emitting diodes with 80% enhanced power efficiency

    SciTech Connect

    Cai, Min; Xiao, Teng; Liu, Rui; Chen, Ying; Shinar, Ruth; Shinar, Joseph

    2011-10-11

    Efficient indium tin oxide (ITO)-free small molecule organic light-emitting diodes (SMOLEDs) with multilayered highly conductive poly(3,4-ethylenedioxy thiophene):poly(styrenesulfonate) (PEDOT:PSS) as the anode are demonstrated. PEDOT:PSS/MoO{sub 3}/N,N'-diphenyl- N,N'-bis(1-naphthylphenyl)-1,1'-biphenyl-4,4'-diamine (NPD)/tris(8-hydroxyquinoline) Al (Alq{sub 3})/4,7-diphenyl-1,10-phenanthroline (BPhen)/LiF/Al SMOLEDs exhibited a peak power efficiency of 3.82 lm/W, 81% higher than that of similar ITO-based SMOLEDs (2.11 lm/W). The improved performance is believed to be due to the higher work function, lower refractive index, and decreased surface roughness of PEDOT:PSS vs ITO, and to Ohmic hole injection from PEDOT:PSS to the NPD layer via the MoO{sub 3} interlayer. The results demonstrate that PEDOT:PSS can substitute ITO in SMOLEDs with strongly improved device performance.

  19. Cloud point extraction of vanadium in pharmaceutical formulations, dialysate and parenteral solutions using 8-hydroxyquinoline and nonionic surfactant.

    PubMed

    Khan, Sumaira; Kazi, Tasneem G; Baig, Jameel A; Kolachi, Nida F; Afridi, Hassan I; Wadhwa, Sham Kumar; Shah, Abdul Q; Kandhro, Ghulam A; Shah, Faheem

    2010-10-15

    A cloud point extraction (CPE) method has been developed for the determination of trace quantity of vanadium ions in pharmaceutical formulations (PF), dialysate (DS) and parenteral solutions (PS). The CPE of vanadium (V) using 8-hydroxyquinoline (oxine) as complexing reagent and mediated by nonionic surfactant (Triton X-114) was investigated. The parameters that affect the extraction efficiency of CPE, such as pH of sample solution, concentration of oxine and Triton X-114, equilibration temperature and time period for shaking were investigated in detail. The validity of CPE of V was checked by standard addition method in real samples. The extracted surfactant-rich phase was diluted with nitric acid in ethanol, prior to subjecting electrothermal atomic absorption spectrometry. Under these conditions, the preconcentration of 50 mL sample solutions, allowed raising an enrichment factor of 125-fold. The lower limit of detection obtained under the optimal conditions was 42 ng/L. The proposed method has been successfully applied to the determination of trace quantity of V in various pharmaceutical preparations with satisfactory results. The concentration ranges of V in PF, DS and PS samples were found in the range of 10.5-15.2, 0.65-1.32 and 1.76-6.93 microg/L, respectively.

  20. Investigation of organic magnetoresistance dependence on spin-orbit coupling using 8-hydroxyquinolinate rare-earth based complexes

    NASA Astrophysics Data System (ADS)

    Carvalho, R. S.; Costa, D. G.; Ávila, H. C.; Paolini, T. B.; Brito, H. F.; Capaz, Rodrigo B.; Cremona, M.

    2016-05-01

    The recently discovered organic magnetoresistance effect (OMAR) reveals the spin-dependent behavior of the charge transport in organic semiconductors. So far, it is known that hyperfine interactions play an important role in this phenomenon and also that spin-orbit coupling is negligible for light-atom based compounds. However, in the presence of heavy atoms, spin-orbit interactions should play an important role in OMAR. It is known that these interactions are responsible for singlet and triplet states mixing via intersystem crossing and the change of spin-charge relaxation time in the charge mobility process. In this work, we report a dramatic change in the OMAR effect caused by the presence of strong intramolecular spin-orbit coupling in a series of rare-earth quinolate organic complex-based devices. Our data show a different OMAR lineshape compared with the OMAR lineshape of tris(8-hydroxyquinolinate) aluminum-based devices, which are well described in the literature. In addition, electronic structure calculations based on density functional theory help to establish the connection between this results and the presence of heavy central ions in the different complexes.

  1. Synthesis, molecular structure, theoretical calculation, DNA/protein interaction and cytotoxic activity of manganese(III) complex with 8-hydroxyquinoline.

    PubMed

    Thamilarasan, V; Sengottuvelan, N; Sudha, A; Srinivasan, P; Siva, A

    2015-01-01

    Manganese(III) complex (1) [Mn(8-hq)3] (where 8-hq=8-hydroxyquinoline) has been synthesized and characterized by elemental, spectral (UV-vis, FT-IR) and thermal analysis. The structure of complex (1) has been determined by single crystal X-ray diffraction studies and the configuration around manganese(III) ion was elongated octahedral coordination geometry. Density functional theory calculations were performed for ligand and its complex. Binding studies of ligand and complex 1 with calf thymus DNA (CT-DNA) was investigated by absorption, fluorescence, circular dichroic (CD) spectroscopy and viscosity measurements. Absorption spectral studies revealed that ligand and complex 1 binds to DNA groove and its intrinsic binding strength has been found to be 2.57×10(4) and 2.91×10(4)M(-1). A molecular docking study confirm that the complex 1 is a minor groove binder and was stabilized through hydrogen bonding interactions. Complex 1 exhibits a good binding propensity to bovine serum albumin (BSA) protein. The in vitro cytotoxicity study of complex 1 on breast cancer cell line (MCF-7) indicate that it has the potential to act as effective anticancer drug, with IC50 values of 3.25μM. The ligand and its complex have been screened for antimicrobial activities and the complex showed better antimicrobial activity than the free ligand.

  2. Toxicity of 8-Hydroxyquinoline in Cryprinus carpio Using the Acute Toxicity Test, Hepatase Activity Analysis and the Comet Assay.

    PubMed

    Yan, Shuaiguo; Chen, Lili; Dou, Xiaofei; Qi, Meng; Du, Qiyan; He, Qiaoqiao; Nan, Mingge; Chang, Zhongjie; Nan, Ping

    2015-08-01

    To evaluate the environmental toxicity of 8-hydroxyquinoline (8-HOQ), an important industrial raw material found in China's major ornamental fish, Cryprinus carpio, using the acute toxicity test, hepatase activity analysis and the comet assay. The results indicated that 8-HOQ had significant acute toxicity in adult C. carpio with a 96 h-LC50 of 1.15 and 0.22 mg L(-1) hepatic quinoline residues as assessed by HPLC. 8-HOQ also induced genotoxicity in the form of strand breaks in the DNA of hepatic cells as shown by the comet assay. With regard to physiological toxicity, 8-HOQ induced a decrease in the activities of hepatic GOT and GPT with increased exposure concentration and time. These data suggest that 8-HOQ may be toxic to the health of aquatic organisms when accidentally released into aquatic ecosystems. The data also suggest that the comet assay may be used in biomonitoring to determine 8-HOQ genotoxicity and hepatic GPT and GOT activities may be potential biomarkers of physiological toxicity.

  3. Structural and optical properties of ε-phase tris(8-hydroxyquinoline) aluminum crystals prepared by using physical vapor deposition method

    NASA Astrophysics Data System (ADS)

    Xie, Wanfeng; Pang, Zhiyong; Zhao, Yu; Jiang, Feng; Yuan, Huimin; Song, Hui; Han, Shenghao

    2014-10-01

    Crystals of ε-phase tris(8-hydroxyquinoline) aluminum (ε-Alq3) were prepared by using physical vapor deposition (PVD) method in a double zone tube furnace. The structural properties of the ε-Alq3 crystals were investigated by using an X-ray single crystal diffractometer (XSCD) and a high resolution scanning electron microscope (SEM). Large straight steps were observed from the side face of the pine needle-like crystals. The straight steps are parallel with each other like terraces and the widths of the steps are fixed, indicating that the ε-Alq3 crystals may have layered structures. The photoluminescence (PL) spectra at different temperatures (7 K, 66 K, 220 K, 300 K and 350 K) and the absorption spectrum were also investigated. The optical band gap of the ε-Alq3 crystals was calculated to be about 2.82 eV. This value is a little larger than that of amorphous mer-Alq3 (about 2.7 eV), indicating a minimizing of impurities, grain boundaries and defects.

  4. Toxicity of 8-Hydroxyquinoline in Cryprinus carpio Using the Acute Toxicity Test, Hepatase Activity Analysis and the Comet Assay.

    PubMed

    Yan, Shuaiguo; Chen, Lili; Dou, Xiaofei; Qi, Meng; Du, Qiyan; He, Qiaoqiao; Nan, Mingge; Chang, Zhongjie; Nan, Ping

    2015-08-01

    To evaluate the environmental toxicity of 8-hydroxyquinoline (8-HOQ), an important industrial raw material found in China's major ornamental fish, Cryprinus carpio, using the acute toxicity test, hepatase activity analysis and the comet assay. The results indicated that 8-HOQ had significant acute toxicity in adult C. carpio with a 96 h-LC50 of 1.15 and 0.22 mg L(-1) hepatic quinoline residues as assessed by HPLC. 8-HOQ also induced genotoxicity in the form of strand breaks in the DNA of hepatic cells as shown by the comet assay. With regard to physiological toxicity, 8-HOQ induced a decrease in the activities of hepatic GOT and GPT with increased exposure concentration and time. These data suggest that 8-HOQ may be toxic to the health of aquatic organisms when accidentally released into aquatic ecosystems. The data also suggest that the comet assay may be used in biomonitoring to determine 8-HOQ genotoxicity and hepatic GPT and GOT activities may be potential biomarkers of physiological toxicity. PMID:26067700

  5. Improvement of (31)P NMR spectral resolution by 8-hydroxyquinoline precipitation of paramagnetic Fe and Mn in environmental samples.

    PubMed

    Ding, Shiming; Xu, Di; Li, Bin; Fan, Chengxin; Zhang, Chaosheng

    2010-04-01

    Solution (31)P nuclear magnetic resonance (NMR) spectroscopy is currently the main method for the characterization of phosphorus (P) forms in environment samples. However, identification and quantification of P compounds may be hampered by poor resolution of spectra caused by paramagnetic Fe and Mn. In this study, a novel technique was developed to improve spectral resolution by removing paramagnetic Fe and Mn from alkaline extracts via 8-hydroxyquinoline (8-HOQ) precipitation. Batch experiments showed that both Fe and Mn were effectively removed by the precipitation at pH 9.0, with the removal efficiencies of 83-91% for Fe and 67-78% for Mn from the extracts of five different environmental samples, while little effect was found on concentration of total P. The (31)P NMR analysis of a model P solution showed that addition of 8-HOQ and its precipitation with metal ions did not alter P forms. Further analyses of the five extracts with (31)P NMR spectroscopy demonstrated that the 8-HOQ precipitation was an ideal method compared with the present postextraction techniques, such as bicarbonate dithionate (BD), EDTA and Chelex-100 treatments, by improving spectral resolution to a large extent with no detrimental effects on P forms. PMID:20201571

  6. Novel Fluorinated 8-Hydroxyquinoline Based Metal Ionophores for Exploring the Metal Hypothesis of Alzheimer’s Disease

    PubMed Central

    2015-01-01

    Zinc, copper, and iron ions are involved in amyloid-beta (Aβ) deposition and stabilization in Alzheimer’s disease (AD). Consequently, metal binding agents that prevent metal-Aβ interaction and lead to the dissolution of Aβ deposits have become well sought therapeutic and diagnostic targets. However, direct intervention between diseases and metal abnormalities has been challenging and is partially attributed to the lack of a suitable agent to determine and modify metal concentration and distribution in vivo. In the search of metal ionophores, we have identified several promising chemical entities by strategic fluorination of 8-hydroxyquinoline drugs, clioquinol, and PBT2. Compounds 15–17 and 28–30 showed exceptional metal ionophore ability (6–40-fold increase of copper uptake and >2-fold increase of zinc uptake) and inhibition of zinc induced Aβ oligomerization (EC50s < ∼5 μM). These compounds are suitable for further development as drug candidates and/or positron emission tomography (PET) biomarkers if radiolabeled with 18F. PMID:26396692

  7. Characterization of 8-hydroxyquinoline derivatives containing aminobenzothiazole as inhibitors of dengue virus type 2 protease in vitro

    PubMed Central

    Lai, Huiguo; Prasad, G. Sridhar; Padmanabhan, Radhakrishnan

    2013-01-01

    Four serotypes of Dengue virus (DENV1–4), mosquito-borne members of Flaviviridae family cause frequent epidemics causing considerable morbidity and mortality in humans throughout tropical regions of the world. There is no vaccine or antiviral therapeutics available for human use. In a previous study, we reported that compounds containing the 8-hydroxyquinoline (8-HQ) scaffold as inhibitors of West Nile virus serine protease. In this study, we analyzed potencies of some compounds with (8-HQ)-aminobenzothiazole derivatives for inhibition of DENV2 protease in vitro. We identified analogs 1–4 with 2-aminothiazole or 2-aminobenzothiazole scaffold with submicromolar potencies (IC50) in the in vitro protease assays. The kinetic constant (Ki) for the most potent 8-HQ-aminobenzothiazoleinhibitor (compound 1) with an IC50 value of 0.91 ± 0.05 µM was determined to be 2.36 ± 0.13 µM. This compound inhibits the DENV2 NS2B/NS3pro by a competitive mode of inhibition. PMID:23127365

  8. Novel tacrine-8-hydroxyquinoline hybrids as multifunctional agents for the treatment of Alzheimer's disease, with neuroprotective, cholinergic, antioxidant, and copper-complexing properties.

    PubMed

    Fernández-Bachiller, María Isabel; Pérez, Concepción; González-Muñoz, Gema C; Conde, Santiago; López, Manuela G; Villarroya, Mercedes; García, Antonio G; Rodríguez-Franco, María Isabel

    2010-07-01

    Tacrine and PBT2 (an 8-hydroxyquinoline derivative) are well-known drugs that inhibit cholinesterases and decrease beta-amyloid (Abeta) levels by complexation of redox-active metals, respectively. In this work, novel tacrine-8-hydroxyquinoline hybrids have been designed, synthesized, and evaluated as potential multifunctional drugs for the treatment of Alzheimer's disease. At nano- and subnanomolar concentrations they inhibit human acetyl- and butyrylcholinesterase (AChE and BuChE), being more potent than tacrine. They also displace propidium iodide from the peripheral anionic site of AChE and thus could be able to inhibit Abeta aggregation promoted by AChE. They show better antioxidant properties than Trolox, the aromatic portion of vitamin E responsible for radical capture, and display neuroprotective properties against mitochondrial free radicals. In addition, they selectively complex Cu(II), show low cell toxicity, and could be able to penetrate the CNS, according to an in vitro blood-brain barrier model.

  9. Structural and vibrational study of 8-hydroxyquinoline-2-carboxaldehyde isonicotinoyl hydrazone - A potential metal-protein attenuating compound (MPAC) for the treatment of Alzheimer's disease

    NASA Astrophysics Data System (ADS)

    de Freitas, Leonardo Viana; da Silva, Cecilia C. P.; Ellena, Javier; Costa, Luiz Antônio Sodré; Rey, Nicolás A.

    2013-12-01

    A comprehensive structural and vibrational study of the potential metal-protein attenuating compound 8-hydroxyquinoline-2-carboxaldehyde isonicotinoyl hydrazone is reported. X-ray diffraction data, as well as FT-IR and Raman frequencies, were compared with the respective theoretical values obtained from DFT calculations. Theory agrees well with experiment. In this context, an attempt of total assignment concerning the FT-IR and Raman spectra of the title compound was performed, shedding new light on previous partial assignments published elsewhere.

  10. A novel trimeric Zn (II) complex based on 8-hydroxyquinoline with trifluoromethylbenzene group: Synthesis, crystal structure, photophysical properties and DNA binding

    NASA Astrophysics Data System (ADS)

    Huo, Yanping; Wang, Chunquan; Lu, Jiguo; Hu, Sheng; Li, Xiaoyang; Zhang, Li

    2015-10-01

    A novel 2-substituted-8-hydroxyquinoline ligand (E)-2-[2-(4-trifluoromethylphenyl)ethenyl]-8-hydroxyquinoline (3, HL) was synthesized and characterized by ESI-MS, NMR spectroscopy and elemental analysis. Using solvothermal method, a trimeric complex [Zn3L6] (4) was fabricated by self-assembly of Zn(II) ions with 3. X-ray structural analysis shows that 4 exhibits a trinuclear core, which was bridged and encapsulated by six 8-hydroxyquinolinate-based ligands. The supramolecular structure of 4 features a lamellar solid constructed by aromatic stacking interactions and nonclassical C-H···F hydrogen bonds derived from 4-trifluoromethylphenyl group of the 3. The coordination behavior of zinc salt and 3 in solution was performed by 1H NMR, UV-vis and Photoluminescence (PL). The experimental results show that the complex 4 emits yellow luminescence in the solid state. To investigate its properties further, we also studied the thermal stability, photophysical properties (fluorescent emission, lifetime) of complex 4, and the interactions between 4 and C60 or EtBr-DNA system.

  11. NMR, DFT and luminescence studies of the complexation of Zn(II) with 8-hydroxyquinoline-5-sulfonate.

    PubMed

    Luísa Ramos, M; Justino, Licínia L G; Branco, Adriana; Duarte, Cláudia M G; Abreu, Paulo E; Fonseca, Sofia M; Burrows, Hugh D

    2011-11-28

    Multinuclear ((1)H, (13)C) magnetic resonance spectroscopy, DFT calculations and luminescence techniques have been used to study 8-hydroxyquinoline-5-sulfonate (8-HQS) and its complexes with Zn(ii), in aqueous solution. The study combines the high sensitivity of luminescence techniques, the selectivity of multinuclear NMR spectroscopy with the structural details accessible through DFT calculations, and aims to obtain a detailed understanding of the complexation between the Zn(2+) ion and 8-HQS. In addition to a complete assignment of the (1)H and (13)C NMR signals of 8-HQS, a full speciation study has been performed. Over the concentration region studied, Zn(2+) metal ion forms only one significant complex species with 8-HQS in aqueous solution in the pH range 6-8. Job's method shows that this species has a 1:2 (metal:ligand) stoichiometry. The geometry around the metal centre, according to structural optimization using DFT calculations, is suggested to be square bipyramidal, with two coordinated water molecules mutually trans, and the remaining positions occupied by the donor groups of the two coordinated 8-HQS ligands. On binding to Zn(ii), 8-HQS shows a marked fluorescence compared with the weakly-luminescent free ligand. In addition, as previously noted, there are marked changes in the absorption spectra, which support the use of 8-HQS as a sensitive fluorescent sensor to detect Zn(2+) metal ion in surface waters, biological fluids, etc. Based on results of the structural studies, suggestions are made of ways for enhancing fluorescence sensitivity.

  12. NMR, DFT and luminescence studies of the complexation of Al(III) with 8-hydroxyquinoline-5-sulfonate.

    PubMed

    Ramos, M Luísa; Justino, Licínia L G; Salvador, Andreia I N; de Sousa, Andreia R E; Abreu, Paulo E; Fonseca, Sofia M; Burrows, Hugh D

    2012-10-28

    Multinuclear ((1)H, (13)C and (27)Al) magnetic resonance spectroscopy (1D and 2D), DFT calculations and fluorescence have been used to study the complexation of 8-hydroxyquinoline-5-sulfonate (8-HQS) with Al(III). The study combines the high sensitivity of luminescence techniques, the selectivity of multinuclear NMR spectroscopy with the structural details accessible through DFT calculations, and aims to provide a detailed understanding of the complexation between the Al(3+) ion and 8-HQS. A full speciation study has been performed and over the concentration region studied, the Al(3+) ion forms complexes with 8-HQS in an aqueous solution in the pH range 2-6. At higher pH, the extensive hydrolysis of the metal limits complexation. Using Job's method, three complexes were detected, with 1 : 1, 1 : 2 and 1 : 3 (metal : ligand) stoichiometries. These results are in agreement with those previously reported using potentiometric and electrochemical techniques. The geometries of the complexes are proposed based on the combination of NMR results with optimized DFT calculations. All the complexes in aqueous solutions at 25 °C are mononuclear species, and have an approximately octahedral geometry with the metal coordinated to one molecule of 8-HQS and four molecules of water (1 : 1 complex), two molecules of 8-HQS and two molecules of water mutually cis (1 : 2 complex), and to three molecules of 8-HQS in non-symmetrical arrangement (mer-isomer), for the 1 : 3 (metal : ligand) complex. On binding to Al(III), 8-HQS shows a more marked fluorescence than the weakly fluorescent free ligand. In addition, as previously noted, there are marked changes in the absorption spectra, which support the use of 8-HQS as a sensitive optical sensor to detect Al(3+) metal ions in surface waters and biological fluids. These complexes also show potential for applications in organic light emitting diodes (OLEDs).

  13. Combined optical gain and degradation measurements in DCM2 doped Tris-(8-hydroxyquinoline)aluminum thin-films

    NASA Astrophysics Data System (ADS)

    Čehovski, Marko; Döring, Sebastian; Rabe, Torsten; Caspary, Reinhard; Kowalsky, Wolfgang

    2016-04-01

    Organic laser sources offer the opportunity to integrate flexible and widely tunable lasers in polymer waveguide circuits, e.g. for Lab-on-Foil applications. Therefore, it is necessary to understand gain and degradation processes for long-term operation. In this paper we address the challenge of life-time (degradation) measurements of photoluminescence (PL) and optical gain in thin-film lasers. The well known guest-host system of aluminum-chelate Alq3 (Tris-(8-hydroxyquinoline)aluminum) as host material and the laser dye DCM2 (4-(Dicyanomethylene)-2- methyl-6-julolidyl-9-enyl-4H-pyran) as guest material is employed as laser active material. Sample layers have been built up by co-evaporation in an ultrahigh (UHV) vacuum chamber. 200nm thick films of Alq3:DCM2 with different doping concentrations have been processed onto glass and thermally oxidized silicon substrates. The gain measurements have been performed by the variable stripe length (VSL) method. This measurement technique allows to determine the thin-film waveguide gain and loss, respectively. For the measurements the samples were excited with UV irradiation (ƛ = 355nm) under nitrogen atmosphere by a passively Q-switched laser source. PL degradation measurements with regard to the optical gain have been done at laser threshold (approximately 3 μJ/cm2), five times above laser threshold and 10 times above laser threshold. A t50-PL lifetime of > 107 pulses could be measured at a maximum excitation energy density of 32 μJ/cm2. This allows for a detailed analysis of the gain degradation mechanism and therefore of the stimulated cross section. Depending on the DCM2 doping concentration C the stimulated cross section was reduced by 35 %. Nevertheless, the results emphasizes the necessity of the investigation of degradation processes in organic laser sources for long-term applications.

  14. Development of a Direct and Continuous Phospholipase D Assay Based on the Chelation-Enhanced Fluorescence Property of 8-Hydroxyquinoline.

    PubMed

    Rahier, Renaud; Noiriel, Alexandre; Abousalham, Abdelkarim

    2016-01-01

    Through its production of phosphatidic acid (PA), phospholipase D (PLD) is strongly involved in vesicular trafficking and cell signaling, making this enzyme an important therapeutic target. However, most PLD assays developed so far are either discontinuous or based on the indirect determination of choline released during PLD-catalyzed phosphatidylcholine hydrolysis, making its kinetic characterization difficult. We present here the development of a direct, specific, and continuous PLD assay that is based on the chelation-enhanced fluorescence property of 8-hydroxyquinoline (8HQ) following Ca(2+) complexation with PLD-generated PA. The real-time fluorescence intensity from 8HQ/Ca(2+)/PA complexes can be converted to concentrations of product using a calibration curve, with a detection limit of 1.2 μM of PA on a microplate scale, thus allowing measurement of the PLD-catalyzed reaction rate parameters. Hence, this assay is well adapted for studying the substrate specificity of PLD, together with its kinetic parameters, using natural phospholipids with various headgroups. In addition, the assay was found to be effective in monitoring the competitive inhibition of PA formation in the production of phosphatidylalcohols following the addition of primary alcohols, such as ethanol, propan-1-ol, or butan-1-ol. Finally, this assay was validated using the purified recombinant Vigna unguiculata PLD, as well as the PLD from Streptomyces chromofuscus, cabbage, or peanuts, and no PA production could be detected using phospholipase A1, phospholipase A2, or phospholipase C, allowing for a reliable determination of PLD activity in crude protein extract samples. This easy to handle PLD assay constitutes, to our knowledge, the first direct and continuous PA determination method on a microplate scale. PMID:26636829

  15. Structural and photophysical studies on gallium(III) 8-hydroxyquinoline-5-sulfonates. Does excited state decay involve ligand photolabilisation?

    PubMed

    Ramos, M Luísa; de Sousa, Andreia R E; Justino, Licínia L G; Fonseca, Sofia M; Geraldes, Carlos F G C; Burrows, Hugh D

    2013-03-14

    Multinuclear ((1)H, (13)C and (71)Ga) magnetic resonance spectroscopy (1D and 2D), DFT calculations and luminescence techniques have been used to study 8-hydroxyquinoline-5-sulfonate (8-HQS) and its complexes with Ga(III) in aqueous solutions. The study combines the high sensitivity of luminescence techniques and the selectivity of multinuclear NMR spectroscopy with the structural details accessible through DFT calculations, and aims to obtain a complete understanding of the complexation between the Ga(3+) ion and 8-HQS, and how this influences the luminescence behaviour. A full speciation study has been performed on this system and three complexes detected, with (metal : ligand) 1 : 1, 1 : 2 and 1 : 3 stoichiometries, the results being consistent with those previously found for the system Al(III)-8-HQS. Complexation in these systems is relevant to their potential biomedical, sensing and optoelectronic applications. On binding to Ga(III), a marked increase is seen in the intensity of the 8-HQS fluorescence band, which is accompanied by changes in the absorption spectra. These support the use of 8-HQS as a sensitive fluorescent sensor to detect Ga(3+) metal ions in surface waters, biological fluids, etc., and its metal complexes as an emitting or charge transport layer in light emitting devices. However, the fluorescence quantum yield of the Ga(III)-8-HQS 1 : 3 complex is about 35% of that of the corresponding system with Al(III). Although this may be due in part to a heavy atom effect favouring S(1)→ T(1) intersystem crossing with Ga(3+), this does not agree with transient absorption measurements on the triplet state yield, which is lower with the Ga(III) system than with Al(III). Instead, it is suggested that photolabilisation of ligand exchange plays a major role in nonradiative decay of the excited state and that this is more efficient with the Ga(3+) complex. Based on these results, suggestions are made of ways of enhancing fluorescence

  16. Structural and photophysical studies on gallium(III) 8-hydroxyquinoline-5-sulfonates. Does excited state decay involve ligand photolabilisation?

    PubMed

    Ramos, M Luísa; de Sousa, Andreia R E; Justino, Licínia L G; Fonseca, Sofia M; Geraldes, Carlos F G C; Burrows, Hugh D

    2013-03-14

    Multinuclear ((1)H, (13)C and (71)Ga) magnetic resonance spectroscopy (1D and 2D), DFT calculations and luminescence techniques have been used to study 8-hydroxyquinoline-5-sulfonate (8-HQS) and its complexes with Ga(III) in aqueous solutions. The study combines the high sensitivity of luminescence techniques and the selectivity of multinuclear NMR spectroscopy with the structural details accessible through DFT calculations, and aims to obtain a complete understanding of the complexation between the Ga(3+) ion and 8-HQS, and how this influences the luminescence behaviour. A full speciation study has been performed on this system and three complexes detected, with (metal : ligand) 1 : 1, 1 : 2 and 1 : 3 stoichiometries, the results being consistent with those previously found for the system Al(III)-8-HQS. Complexation in these systems is relevant to their potential biomedical, sensing and optoelectronic applications. On binding to Ga(III), a marked increase is seen in the intensity of the 8-HQS fluorescence band, which is accompanied by changes in the absorption spectra. These support the use of 8-HQS as a sensitive fluorescent sensor to detect Ga(3+) metal ions in surface waters, biological fluids, etc., and its metal complexes as an emitting or charge transport layer in light emitting devices. However, the fluorescence quantum yield of the Ga(III)-8-HQS 1 : 3 complex is about 35% of that of the corresponding system with Al(III). Although this may be due in part to a heavy atom effect favouring S(1)→ T(1) intersystem crossing with Ga(3+), this does not agree with transient absorption measurements on the triplet state yield, which is lower with the Ga(III) system than with Al(III). Instead, it is suggested that photolabilisation of ligand exchange plays a major role in nonradiative decay of the excited state and that this is more efficient with the Ga(3+) complex. Based on these results, suggestions are made of ways of enhancing fluorescence

  17. Synthesis and luminescence properties of polymeric complexes of Cu(II), Zn(II) and Al(III) with 8-hydroxyquinoline side group-containing polystyrene

    NASA Astrophysics Data System (ADS)

    Gao, Baojiao; Wei, Xiaopeng; Zhang, Yanyan

    2013-01-01

    Three kinds of metalloquinolate-containing polystyrene were prepared via a polymer reaction and a coordination reaction. 5-Chloromethyl-8-hydroxyquinoline (CHQ) was first prepared through the chloromethylation reaction of 8-hydroxyquinoline (HQ) with 1,4-bichloromethoxy-butane as chloromethylation reagent. A polymer reaction, Friedel-Crafts alkylation reaction, was carried out between polystyrene (PS) and CHQ in the presence of Lewis catalyst, and HQ was bonded onto the side chains of PS, obtaining 8-hydroxyquinoline-functionalized Polystyrene, HQ-PS. And then, by using one-pot method with two-stage procedures, the coordination reaction of HQ-PS and small molecule HQ with metal ions including Al(III), Zn(II) and Cu(II) ions, was allowed to be carried out, and three polymeric metalloquinolates, AlQ3-PS, ZnQ2-PS and CuQ2-PS, were successfully prepared, respectively. In the chemical structures of these polymeric metalloquinolates, metalloquinolates were chemically attached onto the side chains of PS. HQ-PS and three polymeric metalloquinolates were fully characterized by FTIR, 1H NMR and TGA. The luminescence properties of the three polymeric metalloquinolates were mainly investigated by UV/Vis absorption spectra and fluorescence emission spectra in solutions and in solid film states. When excited by the ray at about 365 nm, the three polymeric metalloquinolates have blue-green luminescence, and the main emission peaks in the DMF solutions are located at 490, 482 and 502 nm for AlQ3-PS, ZnQ2-PS and CuQ2-PS, respectively. As compared with their emissions in solutions, the emissions in solid film states are red-shifted to some extent, and the main emission peaks are located at 500, 488 and 510 nm for AlQ3-PS, ZnQ2-PS and CuQ2-PS, respectively. Besides, these polymeric metalloquinolates have higher thermal stability than PS as polymeric skeleton.

  18. Determination of aluminium with 8-hydroxyquinoline-5-sulfonic acid in presence of a cationic surfactant by first and second derivative synchronous fluorimetry

    SciTech Connect

    Salinas, F.; de la Pena, A.; Duran, M.S.

    1988-08-01

    An analytical method has been developed for the fluorimetric determination of nanogram amounts of aluminium in solution. The method is based on the reaction of aluminium with 8-hydroxyquinoline-5-sulfonic acid presence of hexadeciltrimethylammonium bromide as a surfactant agent. Synchronous scanned first and second derivative fluorimetry has been employed to increase the sensitivity of the method. The influence of reaction variables as well as instrumental parameters is discussed. The interference of various foreign ions has also been examined and in some cases eliminated or reduced by addition of 1,10-phenanthroline.

  19. Observation of the temperature dependence of the dynamics of photoexcited states in pristine tris(8-hydroxyquinoline) aluminum (AlQ{sub 3})

    SciTech Connect

    Priestley, R.; Walser, A.D.; Dorsinville, R.

    1998-07-01

    The authors have investigated the temperature dependence of the dynamics of radiative excited states in pristine thin films of tris(8-hydroxyquinoline) aluminum (Alq{sub 3}). By measuring the transient photoluminescence (PL) response with subnanosecond resolution, their results revealed an increase in the radiative excited state lifetime and fluorescence quantum yield with decreasing temperature from 300K to 77K. At low temperature the authors observed a decrease in the bimolecular recombination rate constant, singlet exciton diffusion coefficient and diffusion length. A singlet exciton trapping model is used to explain these results.

  20. Solid phase extraction of inorganic mercury using 5-phenylazo-8-hydroxyquinoline and determination by cold vapor atomic fluorescence spectroscopy in natural water samples.

    PubMed

    Daye, Mirna; Ouddane, Baghdad; Halwani, Jalal; Hamzeh, Mariam

    2013-01-01

    8-Hydroxyquinoline (8-HQ) was chosen as a powerful ligand for Hg solid phase extraction. Among several chelating resins based on 8-HQ, 5-phenylazo-8-hydroxyquinoline (5Ph8HQ) is used for mercury extraction in which the adsorption dynamics were fully studied. It has been shown that Hg(II) is totally absorbed by 5Ph8HQ within the first 30 minutes of contact time with t 1/2 5 minutes, following Langmuir adsorption model. At pH 4, the affinity of mercury is unchallenged by other metals except, for Cu(II), which have shown higher Kd value. With these latter characteristics, 5Ph8HQ was examined for the preconcentration of trace levels of Hg(II). The developed method showed quantitative recoveries of Hg(II) with LOD = 0.21 pg mL(-1) and RSD = 3-6% using cold vapor atomic fluorescence spectroscopy (CV-AFS) with a preconcentration factor greater than 250.

  1. Antioxidation and DNA-binding properties of binuclear lanthanide(III) complexes with a Schiff base ligand derived from 8-hydroxyquinoline-7-carboxaldehyde and benzoylhydrazine.

    PubMed

    Liu, Yongchun; Zhang, Kejun; Wu, Yun; Zhao, Junying; Liu, Jianning

    2012-08-01

    8-Hydroxyquinoline-7-carboxaldehyde (8-HQ-7-CA), Schiff-base ligand 8-hydroxyquinoline-7-carboxaldehyde benzoylhydrazone, and binuclear complexes [LnL(NO(3))(H(2)O)(2)](2) were prepared from the ligand and equivalent molar amounts of Ln(NO(3))·6H(2)O (Ln=La(3+), Nd(3+), Sm(3+), Eu(3+), Gd(3+), Dy(3+), Ho(3+), Er(3+), Yb(3+), resp.). Ligand acts as dibasic tetradentates, binding to Ln(III) through the phenolate O-atom, N-atom of quinolinato unit, and C=N and -O-C=N- groups of the benzoylhydrazine side chain. Dimerization of this monomeric unit occurs through the phenolate O-atoms leading to a central four-membered (LnO)(2) ring. Ligand and all of the Ln(III) complexes can strongly bind to CT-DNA through intercalation with the binding constants at 10(5)-10(6) M(-1). Moreover, ligand and all of the Ln(III) complexes have strong abilities of scavenging effects for hydroxyl (HO·) radicals. Both the antioxidation and DNA-binding properties of Ln(III) complexes are much better than that of ligand.

  2. Solid Phase Extraction of Inorganic Mercury Using 5-Phenylazo-8-hydroxyquinoline and Determination by Cold Vapor Atomic Fluorescence Spectroscopy in Natural Water Samples

    PubMed Central

    Daye, Mirna; Halwani, Jalal; Hamzeh, Mariam

    2013-01-01

    8-Hydroxyquinoline (8-HQ) was chosen as a powerful ligand for Hg solid phase extraction. Among several chelating resins based on 8-HQ, 5-phenylazo-8-hydroxyquinoline (5Ph8HQ) is used for mercury extraction in which the adsorption dynamics were fully studied. It has been shown that Hg(II) is totally absorbed by 5Ph8HQ within the first 30 minutes of contact time with t1/2 5 minutes, following Langmuir adsorption model. At pH 4, the affinity of mercury is unchallenged by other metals except, for Cu(II), which have shown higher Kd value. With these latter characteristics, 5Ph8HQ was examined for the preconcentration of trace levels of Hg(II). The developed method showed quantitative recoveries of Hg(II) with LOD = 0.21 pg mL−1 and RSD = 3–6% using cold vapor atomic fluorescence spectroscopy (CV-AFS) with a preconcentration factor greater than 250. PMID:24459417

  3. The importance of holes in aluminium tris-8-hydroxyquinoline (Alq{sub 3}) devices with Fe and NiFe contacts

    SciTech Connect

    Zhang, Hongtao; Desai, P.; Kreouzis, T.; Zhan, Y. Q.; Drew, A. J.; Gillin, W. P.

    2014-01-06

    To study the dominant charge carrier polarity in aluminium tris-8-hydroxyquinoline (Alq{sub 3}) based spin valves, single Alq{sub 3} layer devices with NiFe, ITO, Fe, and aluminium electrodes were fabricated and characterised by Time of Flight (ToF) and Dark Injection (DI) techniques, yielding a lower hole mobility compared to electron mobility. We compare the mobility measured by DI for the dominant carrier injected from NiFe and Fe electrodes into Alq{sub 3}, to that of holes measured by ToF. This comparison leads us to conclude that the dominant charge carriers in Alq{sub 3} based spin valves with NiFe or Fe electrodes are holes.

  4. Fluorimetric determination of tin and organotin compounds in hydroorganic and micellar media in the presence of 8-hydroxyquinoline-5-sulfonic acid.

    PubMed

    Jourquin, G; Mahedero, M C; Paredes, S; Vire, J C; Kauffmann, J M

    1996-06-01

    The fluorescence of tin(IV) complexed by 8-hydroxyquinoline-5-sulfonic acid (8-HQSA) has been studied in both aqueous and hydroorganic (acetate buffer and dimethylsulfoxide) media. Several experimental parameters such as pH, DMSO/water ratio and reactant concentration have been investigated to increase the fluorescence of the tin(IV)-8-HQSA complex. A linear relationship between tin(IV) concentration and fluorescence intensity was observed between 1.7 and 20 microM). Mechanistic and quantitative studies in the presence of surfactants have been performed. Judiciously selected micellar media permitted solubilisation and quantitation of tin(IV) as well as dibutyltin compounds. A linear relationship between concentration and fluorescence intensity was found for mono-, di- and tributyltin with detection limits of 0.1 microM, 0.7 microM and 1 microM, respectively.

  5. A spectrofluorimetric method for cysteine and glutathione using the fluorescence system of Zn(II)-8-hydroxyquinoline-5-sulphonic acid complex.

    PubMed

    Wang, H; Wang, W S; Zhang, H S

    2001-10-01

    The addition of thiol compounds to the fluorescence system of Zn(II)-8-hydroxyquinoline-5-sulphonic acid complex (Zn(II)-HQS) in H3BO3-Na2B4O7 buffer (pH 8.50) solution led to immediate fluorescence inhibition, which was proportional to their amounts. Based on this finding, a novel spectrofluorimetric method for the determination of cysteine (Cys) and reduced glutathione (GSH) has been developed. The detection limits were 17 ng ml(-1) and 0.6 microg ml(-1), respectively. Most amino acids had no interference at high concentrations. The proposed method has been applied to the determination of Cys in protein hydrolysate and cystine electrolyte, and GSH in human blood serum with recoveries of 95.6-104.5%.

  6. Theoretical study on the effects of nitrogen and methyl substitution on tris-(8-hydroxyquinoline) aluminum: an efficient exciton blocking layer for organic photovoltaic cells.

    PubMed

    Lee, Hyunbok; Jeong, Kwangho; Cho, Sang Wan; Yi, Yeonjin

    2012-07-21

    We studied the effect of nitrogen and methyl substitution on tris-(8-hydroxyquinoline) aluminum (Alq(3)) with density functional theory, which has been adopted as an exciton blocking layer (EBL) in organic photovoltaic cells (OPVCs). The substitution of electron withdrawing nitrogen on the phenoxide moiety of Alq(3) lowers the highest molecular orbital (HOMO) level, thus photogenerated excitons can be effectively blocked in OPVC. Additional substitution of methyl on the pyridine moiety makes that Alq(3) has a smaller electron reorganization energy, which results in higher electron mobility with keeping HOMO level almost intact. Therefore, nitrogen and methyl simultaneous substitution shows high performance both in exciton blocking and electron mobility. This is the origins of the short circuit current enhancement in OPVC with 4-hydroxy-8-methyl-1,5-naphthyridine aluminum chelate (Alq(3) with the substitution of both nitrogen and methyl group) EBL.

  7. Effect of oxygen on the magnetic property of Bis(8-hydroxyquinoline)copper (CuQ2): An experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Jiang, Feng; Yuan, Huimin; Xie, Wanfeng; Pang, Zhiyong; Han, Shenghao

    2015-09-01

    The magnetic properties of bis(8-hydroxyquinoline)copper (CuQ2) were investigated by experiments and first-principles density functional theory (DFT) calculations. The as-prepared CuQ2 film shows paramagnetic behavior. After annealing in air, room temperature ferromagnetic (FM) properties were found in CuQ2 film. The Fourier transform infrared spectroscopy (FTIR) analysis indicates a new vibrational mode related to out of plane O-H bend in the annealed film. DFT calculations show that the energy difference between the FM and the antiferromagnetic (AFM) states is greatly increased after O doping, which may be responsible for the room temperature ferromagnetism in the annealed CuQ2 film.

  8. Improved efficiency in organic light-emitting devices with tris-(8-hydroxyquinoline) aluminium doped 9,10-di(2-naphthyl) anthracene emission layer

    NASA Astrophysics Data System (ADS)

    Yuan, Yongbo; Lian, Jiarong; Li, Shuang; Zhou, Xiang

    2008-11-01

    Organic light-emitting devices with tris-(8-hydroxyquinoline) aluminium (Alq3) doped 9,10-di(2-naphthyl) anthracene (ADN) as the emission layer (EML) have been fabricated. These devices exhibit efficient electroluminescence (EL) originated from the Alq3 as the mass ratio of Alq3 to ADN was varied from 1 to 50%. The devices with an optimal Alq3 mass ratio of 10 wt% showed a peak EL efficiency and an external quantum efficiency of 9.1 cd A-1 and 2.7% at a luminance of 1371 cd m-2, which is improved by a factor of 2.2 compared with 4.1 cd A-1 and 1.2% at a luminance of 3267 cd m-2 for conventional devices with the neat Alq3 as the EML.

  9. Preconcentration and purification of rare earth elements in natural waters using silica-immobilized 8-hydroxyquinoline and a supported organophosphorus extractant

    SciTech Connect

    Esser, B.K.; Volpe, A.; Kenneally, J.M.; Smith, D.K. )

    1994-05-15

    8-Hydroxyquinoline immobilized on silica gel (silica-8HQ) and RE-Spec, a supported organophosphorus extractant, were used to preconcentrate and purify rare earth elements (REEs) from natural waters prior to their determination by isotope-dilution inductivity coupled plasma mass spectrometry (ID-ICPMS). Preconcentration onto silica-8HQ is applicable to a wide range of trace metals, making it suitable for multielement ID-ICPMS studies. The silica-8HQ, RE-Spec technique concentrates REEs from 1 L or less of water into 1 mL of salt-free 0.1% nitric acid. The technique is rapid and has high REE yields (>80%) and low REE blanks (<2[minus]6 pg). In addition, Ba separation is high, allowing determination of La and Eu by ID-<300 pg of Ba is present in the final concentrates of sample solutions initially containing > 4 [mu]g of Ba. 24 refs., 2 figs., 4 tabs.

  10. TDDFT study on the excited-state proton transfer of 8-hydroxyquinoline: Key role of the excited-state hydrogen-bond strengthening

    NASA Astrophysics Data System (ADS)

    Lan, Sheng-Cheng; Liu, Yu-Hui

    2015-03-01

    Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations have been employed to study the excited-state intramolecular proton transfer (ESIPT) reaction of 8-hydroxyquinoline (8HQ). Infrared spectra of 8HQ in both the ground and the lowest singlet excited states have been calculated, revealing a red-shift of the hydroxyl group (-OH) stretching band in the excited state. Hence, the intramolecular hydrogen bond (O-H···N) in 8HQ would be significantly strengthened upon photo-excitation to the S1 state. As the intramolecular proton-transfer reaction occurs through hydrogen bonding, the ESIPT reaction of 8HQ is effectively facilitated by strengthening of the electronic excited-state hydrogen bond (O-H···N). As a result, the intramolecular proton-transfer reaction would occur on an ultrafast timescale with a negligible barrier in the calculated potential energy curve for the ESIPT reaction. Therefore, although the intramolecular proton-transfer reaction is not favorable in the ground state, the ESIPT process is feasible in the excited state. Finally, we have identified that radiationless deactivation via internal conversion (IC) becomes the main dissipative channel for 8HQ by analyzing the energy gaps between the S1 and S0 states for the enol and keto forms.

  11. Synthesis, spectroscopic, thermal, voltammetric studies and biological activity of crystalline complexes of pyridine-2,6-dicarboxylic acid and 8-hydroxyquinoline

    NASA Astrophysics Data System (ADS)

    Çolak, Alper Tolga; Çolak, Ferdağ; Yeşilel, Okan Zafer; Büyükgüngör, Orhan

    2009-11-01

    Two new compounds (8-H 2Q) 2[M(dipic) 2]·6H 2O (M = Co ( 1) and Ni ( 2), 8-HQ = 8-hydroxyquinoline, dipic = dipicolinate) have been prepared and characterized by elemental analysis, spectral (IR and UV-vis), thermal analyses, magnetic measurements and single-crystal X-ray diffraction techniques. Both 1 and 2 consist two 8-hydroxyquinolinium cations, one bis(dipicolinate)M(II) anion [M = Co(II), Ni(II)] and six uncoordinated water molecules. Both 1 and 2 crystallize in the monoclinic space group C2/c. In the compounds anion, each dipic ligand simultaneously exhibits tridentate coordination modes through N atom of pyridine ring and oxygen atoms of the carboxylate groups. The crystal packing of 1 and 2 is a composite of intermolecular hydrogen bonding and C-O⋯π interactions. The in vitro antibacterial and antifungal activities of 1 and 2 were evaluated by the agar well diffusion method by MIC tests. Both new compounds showed the same antimicrobial activity against Gram-positive bacteria and yeast and fungi expect Gram-negative bacteria.

  12. A study on the spectroscopic, energy band, and optoelectronic properties of α,ω-dihexylsexithiophene/tris(8-hydroxyquinolinate) gallium blends; DH6T/Gaq3 composite system.

    PubMed

    Muhammad, Fahmi F; Yahya, Mohd Yazid; Ketuly, Kamal Aziz; Muhammad, Abdulkader Jaleel; Sulaiman, Khaulah

    2016-12-01

    In this work the optical response, spectroscopic behaviour, and optoelectronic properties of solution and solid state composite systems based on α,ω-dihexylsexithiophene/tris(8-hydroxyquinolinate) gallium (DH6T/Gaq3) are studied upon the incorporation of different molar percentages of Gaq3. UV-vis, PL, FTIR spectrophotometers and SEM technique were utilized to perform the investigations. The results showed a reduced energy band (Eg) (from 2.33eV to 1.83eV) and a broadened absorption spectrum for the blend system when 29.8% molar of Gaq3 was incorporated. These were attributed to the enhanced intermolecular interactions that are brought about by the increased strength of π-π overlap between the molecular moieties. A mathematical formula was developed to interpret the non-monotonic change occurred in Eg, while numerical calculations have been made to assign the type and nature of the electronic transitions governing the spectroscopic behaviour of the system. The results were elaborated and comprehensively discussed in terms of the exciton generation, energy band theory, molecular interactions, and spatial geometry.

  13. Structural, electronic, and magnetic properties of tris(8-hydroxyquinoline)iron(III) molecules and their magnetic coupling with ferromagnetic surface: first-principles study

    NASA Astrophysics Data System (ADS)

    Jiang, W.; Zhou, M.; Liu, Z.; Sun, D.; Vardeny, Z. V.; Liu, F.

    2016-05-01

    Using first-principles calculations, we have systematically investigated the structural, electronic, and magnetic properties of facial (fac-) and meridional (mer-) tris(8-hydroxyquinoline)iron(III) (Feq3) molecules and their interaction with ferromagnetic substrate. Our calculation results show that for the isolated Feq3, mer-Feq3 is more stable than the fac-Feq3; both Feq3 isomers have a high spin-state of 5 μ B as the ground state when an on-site Hubbard-U term is included to treat the highly localized Fe 3d electrons; while the standard DFT calculations produce a low spin-state of 1 μ B for mer-Feq3. These magnetic behaviors can be understood by the octahedral ligand field splitting theory. Furthermore, we found that fac-Feq3 has a stronger bonding to the Co surface than mer-Feq3 and an anti-ferromagnetic coupling was discovered between Fe and Co substrate, originating from the superexchange coupling between Fe and Co mediated by the interface oxygen and nitrogen atoms. These findings suggest that Feq3 molecular films may serve as a promising spin-filter material in spintronic devices.

  14. Paramagnetic relaxation enhancement of membrane proteins by incorporation of the metal-chelating unnatural amino acid 2-amino-3-(8-hydroxyquinolin-3-yl) propanoic acid (HQA)

    PubMed Central

    Park, Sang Ho; Wang, Vivian; Radoicic, Jasmina; De Angelis, Anna A.; Berkamp, Sabrina; Opella, Stanley J.

    2014-01-01

    The use of paramagnetic constraints in protein NMR is an active area of research because of the benefits of long-range distance measurements (>10 Å). One of the main issues in successful execution is the incorporation of a paramagnetic metal ion into diamagnetic proteins. The most common metal ion tags are relatively long aliphatic chains attached to the side chain of a selected cysteine residue with a chelating group at the end where it can undergo substantial internal motions, decreasing the accuracy of the method. An attractive alternative approach is to incorporate an unnatural amino acid (UAA) that binds metal ions at a specific site on the protein using the methods of molecular biology. Here we describe the successful incorporation of the unnatural amino acid 2-amino-3-(8-hydroxyquinolin-3-yl) propanoic acid (HQA) into two different membrane proteins by heterologous expression in E. coli. Fluorescence and NMR experiments demonstrate complete replacement of the natural amino acid with HQA and stable metal chelation by the mutated proteins. Evidence of site-specific intra- and inter-molecular PREs by NMR in micelle solutions sets the stage for the use of HQA incorporation in solid-state NMR structure determinations of membrane proteins in phospholipid bilayers. PMID:25430059

  15. White light emission from Mn2 + doped ZnS nanocrystals through the surface chelating of 8-hydroxyquinoline-5-sulfonic acid

    NASA Astrophysics Data System (ADS)

    Lü, Xiaodan; Yang, Jing; Fu, Yuqin; Liu, Qianqian; Qi, Bin; Lü, Changli; Su, Zhongmin

    2010-03-01

    White light emitting semiconductor nanocrystals (NCs) have been successfully synthesized from 8-hydroxyquinoline-5-sulfonic acid (HQS) decorated manganese doped ZnS NCs through fine tuning the surface-coordination emission and dopant emission of the NC host. The HQS functionalized manganese doped ZnS NCs (QS-ZnS:Mn), with a cubic crystal structure, have the same diameter of about 4.0 nm as ZnS:Mn NCs without HQS. The intensity of the surface-coordination emission peak increased with increasing HQS content or augmenting excited wavelength. The emission of white light was achieved by carefully controlling the dosage of HQS in NCs and appropriately tuning the excited wavelength. The color coordinates (0.35, 0.34) for the efficient white light emitting NCs were very close to the ideal Commission Internationale de l'Eclairage (CIE) chromaticity coordinates for pure white light (0.33, 0.33). The photoluminescence (PL) decay study revealed that the white light emitting NCs exhibited maximum lifetime values at different emission peaks for different NC samples. The study results also indicated that the HQS molecules were attached to the surface of ZnS:Mn NCs in a single coordination fashion due to the steric hindrance effect of the special spherical surface of NCs, which made the QS-ZnS:Mn NCs possess stable and high fluorescent properties in different organic solvents as compared with the conventional small molecule complexes.

  16. White light emission from Mn2 + doped ZnS nanocrystals through the surface chelating of 8-hydroxyquinoline-5-sulfonic acid.

    PubMed

    Lü, Xiaodan; Yang, Jing; Fu, Yuqin; Liu, Qianqian; Qi, Bin; Lü, Changli; Su, Zhongmin

    2010-03-19

    White light emitting semiconductor nanocrystals (NCs) have been successfully synthesized from 8-hydroxyquinoline-5-sulfonic acid (HQS) decorated manganese doped ZnS NCs through fine tuning the surface-coordination emission and dopant emission of the NC host. The HQS functionalized manganese doped ZnS NCs (QS-ZnS:Mn), with a cubic crystal structure, have the same diameter of about 4.0 nm as ZnS:Mn NCs without HQS. The intensity of the surface-coordination emission peak increased with increasing HQS content or augmenting excited wavelength. The emission of white light was achieved by carefully controlling the dosage of HQS in NCs and appropriately tuning the excited wavelength. The color coordinates (0.35, 0.34) for the efficient white light emitting NCs were very close to the ideal Commission Internationale de l'Eclairage (CIE) chromaticity coordinates for pure white light (0.33, 0.33). The photoluminescence (PL) decay study revealed that the white light emitting NCs exhibited maximum lifetime values at different emission peaks for different NC samples. The study results also indicated that the HQS molecules were attached to the surface of ZnS:Mn NCs in a single coordination fashion due to the steric hindrance effect of the special spherical surface of NCs, which made the QS-ZnS:Mn NCs possess stable and high fluorescent properties in different organic solvents as compared with the conventional small molecule complexes.

  17. Spray-dried chitosan microspheres containing 8-hydroxyquinoline -5 sulphonic acid as a new adsorbent for Cd(II) and Zn(II) ions.

    PubMed

    Vitali, Luciano; Laranjeira, Mauro C M; Gonçalves, Norberto S; Fávere, Valfredo T

    2008-03-01

    In the present study, a new chelating adsorbent was prepared from chitosan microspheres cross-linked with glutaraldehyde by spray drying using 8-hydroxyquinoline -5 sulphonic acid as chelant agent (CTS-SX-CL). Microspheres of the new adsorbent were characterized by Raman spectroscopy, scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX). The effect of pH, contact time and concentration of metallic ions in solution were evaluated on the adsorption behavior of Cd(II) and Zn(II) by CTS-SX-CL. Adsorption was maximum for both Cd(II) and Zn(II) at pH 8.0. Adsorption kinetic curves were obtained and could be fit by the pseudo second-order adsorption model. An analysis of equilibrium adsorption data using the Langmuir isotherm model indicated that the maximum adsorption capacity of CTS-SX-CL was higher than that of CTS-CL for both ions investigated. The adsorption capacity increased 74% for Cd(II).

  18. Use of 8-hydroxyquinoline-chitosan chelating resin in an automated on-line preconcentration system for determination of zinc(II) by F AAS.

    PubMed

    Carletto, Jeferson Schneider; Roux, Kalya Cravo Di Pietro; Maltez, Heloisa França; Martendal, Edmar; Carasek, Eduardo

    2008-08-30

    This study presents the development of an on-line preconcentration system for zinc(II) determination in aqueous samples. The analyte was trapped in a mini-column filled with a chelating resin based on a chitosan biopolymer modified with 8-hydroxyquinoline obtained by the diazotization reaction. Flow and chemical variables of the system, as well as the potential interference ions, were optimized through a multivariate procedure. The factors selected were sample pH, eluent concentration (HNO(3)), and sample and eluent flow rates. It was verified through a full factorial design that the sample pH and eluent flow rate factors were statistically significant at the 95% confidence level. A final optimization of the significant factors was carried out using a Doehlert matrix. The preconcentration system was linear between 2.5 and 75 microgL(-1), with a regression coefficient of 0.9995. The enrichment factor was 17.6. The limits of detection and quantification were 0.8 and 2.5 microgL(-1), respectively. The repeatability and the analytical frequency were, respectively, 2.7 (25.0 microgL(-1), n=8) and 18 samples per hour. Results for recovery tests using mineral water samples were between 85 and 93%. Certified reference materials were analyzed in order to check the accuracy of the proposed method.

  19. Photophysical properties of 8-hydroxyquinoline-5-sulfonic acid as a function of the pH: a TD-DFT investigation.

    PubMed

    Le Bahers, Tangui; Adamo, Carlo; Ciofini, Ilaria

    2010-05-13

    Time dependent density functional theory (TD-DFT) in conjunction with a hybrid exchange correlation functional (PBE0) were applied to characterize the photophysical behavior of the 8-hydroxyquinoline-5-sulfonic acid (8-HQS) in solution as a function of the pH. In particular, absorption and emission spectra of each species as well as their relative stability in the first excited state were computed. From these calculations it is possible to directly derive quantities otherwise hardly experimentally accessible such as excited state acidic dissociation constants (pK(a)*) and corresponding distribution diagrams at the excited state. These two latter quantities were determined by first principles from the relative stabilities of the species at the excited state computed at the TD-DFT level. Consequently, the evolution of the absorption and emission spectral properties of 8-HQS as a function of the pH could be fully simulated from first principles. Finally, insights on energetics and the mechanism of the phototautomerization reaction supposed to be responsible for the absence of fluorescence of the 8-HQS molecule were derived from the calculations.

  20. A study on the spectroscopic, energy band, and optoelectronic properties of α,ω-dihexylsexithiophene/tris(8-hydroxyquinolinate) gallium blends; DH6T/Gaq3 composite system.

    PubMed

    Muhammad, Fahmi F; Yahya, Mohd Yazid; Ketuly, Kamal Aziz; Muhammad, Abdulkader Jaleel; Sulaiman, Khaulah

    2016-12-01

    In this work the optical response, spectroscopic behaviour, and optoelectronic properties of solution and solid state composite systems based on α,ω-dihexylsexithiophene/tris(8-hydroxyquinolinate) gallium (DH6T/Gaq3) are studied upon the incorporation of different molar percentages of Gaq3. UV-vis, PL, FTIR spectrophotometers and SEM technique were utilized to perform the investigations. The results showed a reduced energy band (Eg) (from 2.33eV to 1.83eV) and a broadened absorption spectrum for the blend system when 29.8% molar of Gaq3 was incorporated. These were attributed to the enhanced intermolecular interactions that are brought about by the increased strength of π-π overlap between the molecular moieties. A mathematical formula was developed to interpret the non-monotonic change occurred in Eg, while numerical calculations have been made to assign the type and nature of the electronic transitions governing the spectroscopic behaviour of the system. The results were elaborated and comprehensively discussed in terms of the exciton generation, energy band theory, molecular interactions, and spatial geometry. PMID:27372510

  1. Synthesis and electroluminescence characterization of a new aluminum complex, [8-hydroxyquinoline] bis [2, 2'bipyridine] aluminum Al(Bpy)2q

    NASA Astrophysics Data System (ADS)

    Rahul, Kumar; Ritu, Srivastava; Punita, Singh

    2016-01-01

    We have synthesized and characterized a new electroluminescent material, [8-hydroxyquinoline] bis [2,2'bipyridine] aluminum. A solution of this material Al(Bpy)2q in toluene showed absorption maxima at 380 nm, which was attributed to the moderate energy (π-π*) transitions of the aromatic rings. The photoluminescence spectrum of Al(Bpy)2q in the toluene solution showed a peak at 518 nm. This material shows thermal stability up to 300 °C. The structure of the device is ITO/F4-TCNQ (1 nm)/α-NPD (35 nm)/Al(Bpy)2q (35 nm)/ BCP (6 nm)/Alq3 (28 nm)/LiF (1 nm)/Al (150 nm). This device exhibited a luminescence peak at 515 nm (CIE coordinates, x = 0.32, y = 0.49). The maximum luminescence of the device was 214 cd/m2 at 21 V. The maximum current efficiency of OLED was 0.12 cd/A at 13 V and the maximum power efficiency was 0.03 lm/W at 10 V.

  2. Synthesis and electroluminescence properties of a new aluminium complex [5-choloro-8-hydroxyquinoline] bis [2,2'bipyridine] Aluminium Al(Bpy)2(5-Clq)

    NASA Astrophysics Data System (ADS)

    Kumar, Rahul; Bhargava, Parag; Srivastava, Ritu; Singh, Punita

    2015-11-01

    We have synthesized a new aluminium complex, [5-choloro-8-hydroxyquinoline] bis[2,2'bipyridine] Aluminium Al(Bpy)2(5-Clq) and characterized it for structural, thermal and photoluminescence properties. The prepared material was characterized by Fourier -transformed infra-red spectroscopy (FTIR), thermal gravimetric analysis (TGA) and photoluminescence. The prepared material showed thermal stability up to 240 °C. The photoluminescence spectrum of Al(Bpy)2(5-Clq) in toluene solution showed peak at 515 nm. This material was used as an emissive layer in organic light emitting diodes (OLEDs). The fundamental structure of device is ITO/F4-TCNQ(1 nm)/α-NPD(35 nm)/Al(Bpy)2(5-Clq) (35 nm)/BCP(6 nm)/Alq3(28 nm)/LiF(1 nm)/Al(150 nm). The device emits an yellowish green light (CIE coordinates, x = 0.32, y = 0.52) with maximum luminescence 314 Cd/m2 at 18 V. The maximum current efficiency of OLED was 0.09 Cd/A and maximum power efficiency was 0.03 lm/W at 9 V respectively.

  3. Structural, electronic, and magnetic properties of tris(8-hydroxyquinoline)iron(III) molecules and their magnetic coupling with ferromagnetic surface: first-principles study.

    PubMed

    Jiang, W; Zhou, M; Liu, Z; Sun, D; Vardeny, Z V; Liu, F

    2016-05-01

    Using first-principles calculations, we have systematically investigated the structural, electronic, and magnetic properties of facial (fac-) and meridional (mer-) tris(8-hydroxyquinoline)iron(III) (Feq3) molecules and their interaction with ferromagnetic substrate. Our calculation results show that for the isolated Feq3, mer-Feq3 is more stable than the fac-Feq3; both Feq3 isomers have a high spin-state of 5 μB as the ground state when an on-site Hubbard-U term is included to treat the highly localized Fe 3d electrons; while the standard DFT calculations produce a low spin-state of 1 μB for mer-Feq3. These magnetic behaviors can be understood by the octahedral ligand field splitting theory. Furthermore, we found that fac-Feq3 has a stronger bonding to the Co surface than mer-Feq3 and an anti-ferromagnetic coupling was discovered between Fe and Co substrate, originating from the superexchange coupling between Fe and Co mediated by the interface oxygen and nitrogen atoms. These findings suggest that Feq3 molecular films may serve as a promising spin-filter material in spintronic devices. PMID:27044670

  4. Tumor Cellular Proteasome Inhibition and Growth Suppression by 8-Hydroxyquinoline and Clioquinol Requires Their Capabilities to Bind Copper and Transport Copper into Cells

    PubMed Central

    Zhai, Shumei; Yang, Lei; Cui, Qiuzhi Cindy; Sun, Ying; Dou, Q. Ping; Yan, Bing

    2009-01-01

    We have previously reported that when mixed with copper, 8-hydroxyquinoline (8-OHQ) and its analog clioquinol (CQ) inhibited the proteasomal activity and proliferation in cultured human cancer cells. CQ treatment of high copper-containing human tumor xenografts also caused cancer suppression, associated with proteasome inhibition in vivo. However, the nature of copper dependence of these events has not been elucidated experimentally. In the current study, by using chemical probe molecules that mimic structures of 8-OHQ and CQ, but have no copper binding capability, we dissected the complex cellular processes elicited by 8-OHQ-Cu or CQ-Cu mixture and revealed that copper-binding to 8-OHQ or CQ is required for transportation of copper complex into human breast cancer cells and the consequent proteasome-inhibitory, growth-suppressive and apoptosis-inducing activities. In contrast, the non-copper-binding analogs of 8-OHQ or CQ blocked the very first step – copper binding in this chain of events mediated by 8-OHQ-Cu or CQ-Cu. PMID:19809836

  5. High-performance supercapacitor based on nitrogen-doped porous carbon derived from zinc(II)-bis(8-hydroxyquinoline) coordination polymer.

    PubMed

    Chen, Xiang Ying; Xie, Dong Hua; Chen, Chong; Liu, Jian Wei

    2013-03-01

    Nitrogen-doped porous carbon electrodes with remarkable specific capacitance have been fabricated by the rational carbonization of zinc(II)-bis(8-hydroxyquinoline) (abbr. Znq(2)) coordination polymer, and heating treatment with CO(NH(2))(2). The experimental results demonstrate that the mass ratio of carbon precursor and CO(NH(2))(2) plays a key role in the formation of porous carbon with various nitrogen content as well as specific surface areas and pore structures. The cyclic voltammetry and galvanostatic charge-discharge measurements show that the capacitive performance has been remarkably improved by doping with nitrogen. The specific capacitance of 219.2 F g(-1) is achieved at the current density of 1 A g(-1) with nitrogen-doped porous carbon, increasing up to ca. 56.8% compared to that with pristine porous carbon. The nitrogen-doped porous carbon electrode exhibits enhance capacitance retention as ca. 45.2% at 20 A g(-1) as well as cycling stability (ca. 7.6% loss after 3000 cycles). The present carbonization method as well as the nitrogen-doping method for porous carbon from coordination polymer can enrich the strategies for the production of carbon-based electrodes materials in the application of electrochemical capacitors.

  6. TDDFT study on the excited-state proton transfer of 8-hydroxyquinoline: key role of the excited-state hydrogen-bond strengthening.

    PubMed

    Lan, Sheng-Cheng; Liu, Yu-Hui

    2015-03-15

    Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations have been employed to study the excited-state intramolecular proton transfer (ESIPT) reaction of 8-hydroxyquinoline (8HQ). Infrared spectra of 8HQ in both the ground and the lowest singlet excited states have been calculated, revealing a red-shift of the hydroxyl group (-OH) stretching band in the excited state. Hence, the intramolecular hydrogen bond (O-H···N) in 8HQ would be significantly strengthened upon photo-excitation to the S1 state. As the intramolecular proton-transfer reaction occurs through hydrogen bonding, the ESIPT reaction of 8HQ is effectively facilitated by strengthening of the electronic excited-state hydrogen bond (O-H···N). As a result, the intramolecular proton-transfer reaction would occur on an ultrafast timescale with a negligible barrier in the calculated potential energy curve for the ESIPT reaction. Therefore, although the intramolecular proton-transfer reaction is not favorable in the ground state, the ESIPT process is feasible in the excited state. Finally, we have identified that radiationless deactivation via internal conversion (IC) becomes the main dissipative channel for 8HQ by analyzing the energy gaps between the S1 and S0 states for the enol and keto forms.

  7. Highly sensitive gold nanoparticles-based optical sensing of DNA hybridization using bis(8-hydroxyquinoline-5-solphonate)cerium(III) chloride as a novel fluorescence probe.

    PubMed

    Shamsipur, Mojtaba; Memari, Zahra; Ganjali, Mohammad Reza; Norouzi, Parviz; Faridbod, Farnoush

    2016-01-25

    A simple and sensitive method for the detection of DNA hybridization in a homogeneous format was developed, using bis(8-hydroxyquinoline-5-solphonate)cerium(III) chloride (Ce(QS)2Cl) as a novel fluorescent probe. The method is based on fluorescence quenching by gold nanoparticles used as both nanoscafolds for the immobilization of the probe DNA sequence, which is related to Alicyclobacillus acidophilus strain TA-67 16S ribosomal RNA, and nanoquenchers of the Ce(QS)2Cl probe. The probe DNA-functionalized GNPs were synthesized by derivatizing the colloidal gold nanoparticles solution with 3-thiolated 16-base oligonucleotides. Addition of sequence-specific target DNAs (16 bases) into the mixture containing probe DNA-functionalized GNPs and fluorescent probe lead to the quenching of Ce(QS)2Cl fluorescence at 360 nm (λex=270 nm), due to DNA hybridization, the resulting quenched intensity being proportional to the concentration of target DNA. Under optimal conditions of pH 7.4 and Ce(QS)2Cl concentration of 1.0 × 10(-7) M, the linear dynamic range found to be 1.0 × 10(-10)-3.0 × 10(-8) M DNA, with a limit of detection of 7.0 × 10(-11) M. The interaction mechanism for the binding of Ce(QS)2Cl to DNA was studied in detail, and results proved that the interaction mode between Ce(QS)2Cl and DNA is groove binding, with a binding constant of 1.0 × 10(5) M(-1).

  8. An effective in vitro and in vivo antileishmanial activity and mechanism of action of 8-hydroxyquinoline against Leishmania species causing visceral and tegumentary leishmaniasis.

    PubMed

    Costa Duarte, Mariana; dos Reis Lage, Letícia Martins; Lage, Daniela Pagliara; Mesquita, Juliana Tonini; Salles, Beatriz Cristina Silveira; Lavorato, Stefânia Neiva; Menezes-Souza, Daniel; Roatt, Bruno Mendes; Alves, Ricardo José; Tavares, Carlos Alberto Pereira; Tempone, André Gustavo; Coelho, Eduardo Antonio Ferraz

    2016-02-15

    The development of new therapeutic strategies to treat leishmaniasis has become a priority. In the present study, the antileishmanial activity of 8-hydroxyquinoline (8-HQN) was investigated against in vitro promastigotes and in vivo intra-macrophage amastigotes of three Leishmania species: Leishmania amazonensis, Leishmania infantum and Leishmania braziliensis. Studies were performed to establish the 50% Leishmania inhibitory concentration (IC50) of 8-HQN, as well as its 50% cytotoxic concentration (CC50) on murine macrophages and in human red blood cells. The inhibition of macrophages infection was also evaluated using parasites that were pre-treated with 8-HQN. The effects of this compound on nitric oxide (NO) production and in the mitochondrial membrane potential were also evaluated. Finally, the therapeutic efficacy of 8-HQN was assessed in a known murine model, L. amazonensis-chronically infected BALB/c mice. Our results showed that 8-HQN was effective against promastigote and amastigote stages of all tested Leishmania species, presenting a selectivity index of 328.0, 62.0 and 47.0 for L. amazonensis, L. infantum and L. braziliensis, respectively. It was effective in treating infected macrophages, as well as in preventing the infection of these cells using pre-treated parasites. In addition, 8-HQN caused an alteration in the mitochondrial membrane potential of the parasites. When administered at 10mg/kg body weight/day by subcutaneous route, this product was effective in reducing the lesion diameter, as well as the parasite load in evaluated tissues and organs of infected animals. The results showed the in vitro and in vivo efficacy of 8-HQN against three different Leishmania species causing tegumentary and/or visceral leishmaniasis, and it could well be used for future therapeutic optimization studies to treat leishmaniasis.

  9. 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

  10. Oxocomplexes of Mo(VI) and W(VI) with 8-hydroxyquinoline-5-sulfonate in solution: structural studies and the effect of the metal ion on the photophysical behaviour.

    PubMed

    Ramos, M Luísa; Justino, Licínia L G; Abreu, Paulo E; Fonseca, Sofia M; Burrows, Hugh D

    2015-11-28

    Multinuclear ((1)H, (13)C, (95)Mo and (183)W) NMR spectroscopy, combined with DFT calculations, provides detailed information on the complexation between the Mo(VI) and W(VI) oxoions and 8-hydroxyquinoline-5-sulfonate (8-HQS) in aqueous solution. Over the concentration region studied, Mo(VI) and W(VI) oxoions form three homologous complexes with 8-HQS in water in the pH range 2-8. Two of these, detected at pH < 6, are mononuclear 1 : 2 (metal : ligand) isomers, with the metal centre (MO2(2+)) coordinated to two 8-HQS ligands. An additional complex, dominant at slightly higher pH values (5-8) for solutions with a 1 : 1 metal : ligand molar ratio, has a binuclear M2O5(2+) centre coordinated to two 8-HQS ligands. The two metal atoms are bridged by three oxygen atoms, two coming from 8-HQS, together with the M-O-M bridge of the bimetallic centre. We show that the long-range exchange corrected BOP functional with local response dispersion (LCBOPLRD), together with explicit solvent molecules, leads to geometries that readily converge to equilibrium structures having realistic bridging O8-HQS-M bonds. Previous attempts to calculate the structures of such binuclear complexes using DFT with the B3LYP functional have failed due to difficulties in treating the weak interaction in these bridged structures. We believe that the LCBOPLRD method may be of more general application in theoretical studies in related binuclear metal complexes. UV/visible absorption and luminescence spectra of all the complexes have also been recorded. The complex between Mo(vi) and 8-HQS is only weakly luminescent, in contrast to what has been observed with this ligand and many other metal ions. We suggest that this is due to the presence of low-lying ligand-to-metal charge transfer (LMCT) states close to the emitting ligand-based level which quench the emission. However, with W(VI), DFT calculations show that the LMCT states are now much higher in energy than the ligand based levels

  11. On the mechanism of divalent metal ion chelator induced activation of the 7S nerve growth factor esteropeptidase. Activation by 2,2',2''-terpyridine and by 8-hydroxyquinoline 5-sulfonic acid.

    PubMed

    Pattison, S E; Dunn, M F

    1976-08-24

    Our previous studies (Pattison, S. E., and Dunn, M. F. (1975), Biochemistry 14, 2733) have shown that the reaction of divalent metal ion chelators with the 140 000 mol wt mouse submaxillary nerve growth factor protein (7S NGF) activates the iota-subunit esteropeptidase activity ca. sevenfold. Ultraviolet-visible spectral studies with the chelator 2,2',2''-terpyridine (terpyridine) and fluorescence emission studies with 8-hydroxyquinoline-5-sulfonic acid (HQSA) in combination with both conventional and rapid-mixing stopped-flow kinetic techniques have been employed in the present study to investigate (a) the mechanism of the chelator-induced activation process, and (b) the identity of the divalent metal ion involved. The spectral studies confirm the presence of stoichiometrically significant amounts of tightly bound zinc ion in native 7S NGF (1-2 g-atoms of An2+/mol of 7S NGF). The kinetic studies show that the reaction of terpyridine with 7S NGF occurs via a two-step process involving first a rapid, apparent second-order step (k1 = 1 x 10(6) M-1 s-1) to form a 7S NGF-Zn2+-chelator monocomplex, then a slow step to form a bis(terpyridine)-Zn(II) complex and activated 7S NGF in an apparent first-order process (kobsd = 0.10 min-1). This rate is, within experimental error, identical with the apparent first-order rate constant for the chelator-induced activation process (monitored by the rate of change in the steady-state rate of hydrolysis of chromophoric substrate, alpha-N-benzoyl-D,L-arginine-p-nitroanilide). Kinetic studies of the reaction of HQSA with native 7S NGF show that, under the same conditions of concentration, the rate of formation of the tris(HQSA)-Zn(II) complex is identical with the rate of the HQSA-induced activation of the 7S NGF esteropeptidase. Thus, these studies unambiguously establish that zinc ion is the metal ion involved in the chelator-induced activation process, and that activation involves removal of zinc ion from native 7S NGF.

  12. Investigation on growth, structure and characterization of succinate salt of 8-hydroxyquinoline: An organic NLO crystal

    NASA Astrophysics Data System (ADS)

    Thirumurugan, R.; Babu, B.; Anitha, K.; Chandrasekaran, J.

    2015-04-01

    8-Hydroxyquinolinium succinate (8-HQSU) has been synthesized and single crystals were grown from ethanol solvent by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated by single crystal X-ray diffraction analysis. It reveals that 8-HQSU crystallizes in monoclinic system with non-centro symmetric space group P21. FTIR, 1H and 13C NMR spectral investigations have been carried out to identify the vibrational modes of various functional groups and placement of proton and carbon in the 8-HQSU compound, respectively. UV-vis-NIR transmission spectrum shows the cutoff wavelength around 357 nm. In addition, a photoluminescence spectral analysis was carried out for 8-HQSU crystals. The thermal properties of crystals were evaluated from TGA and DTA techniques and the crystal was found to be stable up to 145 °C. The dielectric studies show that the dielectric constant and dielectric loss decrease exponentially with frequency at different temperatures. Photoconductivity studies were carried out on the grown crystals it reveals the positive photo conducting nature. Powder second harmonic generation property of the crystal was confirmed by Kurtz and Perry powder SHG technique and it is found to be 1.3 times greater than that of KDP.

  13. Single-Molecule-Magnet Behavior and Fluorescence Properties of 8-Hydroxyquinolinate Derivative-Based Rare-Earth Complexes.

    PubMed

    Gao, Hong-Ling; Jiang, Li; Wang, Wen-Min; Wang, Shi-Yu; Zhang, Hong-Xia; Cui, Jian-Zhong

    2016-09-01

    Five tetranuclear rare-earth complexes, [RE4(dbm)4L6(μ3-OH)2] [HL = 5- (4-fluorobenzylidene)-8-hydroxylquinoline; dbm = 1,3-diphenyl-1,3-propanedione; RE = Y (1), Eu (2), Tb (3), Dy (4), Lu (5)], have been synthesized and completely characterized. The X-ray structural analyses show that each [RE4] complex is of typical butterfly or rhombus topology. Each RE(III) center exists in an eight-coordinated square-antiprism environment. Magnetic studies reveal that complex 4 displays single-molecule-magnet behavior below 10 K under a zero direct-current field, with an effective anisotropy barrier (ΔE/kB = 56 K). The fluorescence properties of complexes 1-5 were also investigated. Complexes 2-4 showed their characteristic peaks for the corresponding RE(III) center, while complexes 1 and 5 showed the same emission peaks with the ligand when they were excited at the same wavelength. PMID:27560459

  14. Understanding the role of electron and hole trions on current transport in aluminium tris(8-hydroxyquinoline) using organic magnetoresistance

    SciTech Connect

    Zhang, Sijie; Gillin, W. P.; Willis, M.; Gotto, R.; Roy, K. A.; Kreouzis, T.; Rolfe, N. J.

    2014-01-27

    The change in current through an organic light emitting diode (OLED) when it is placed in a magnetic field has been dubbed organic magnetoresistance and provides a means to understand the spin interactions that are occurring in working devices. Whilst there are a wide range of interactions that have been proposed to be the cause of the measured effects, there is still a need to identify their individual roles and in particular how they respond to an applied magnetic field. In this work, we investigate the effect of changing the balance of electron and hole injection in a simple aluminium tris(8-hydroxyqinoline) based OLED and demonstrate that the triplet polaron interaction appears to be much stronger for electrons than for holes in this material.

  15. The Influences of different cathode materials on Tris-(8-Hydroxyquinoline)- Aluminum Doped with CsNO3 in Organic Light emitting Devices

    NASA Astrophysics Data System (ADS)

    Chen, Mei-Hsin; Lu, Yin-Jui; Wu, Chung-Chih; Wu, Chih-I.

    2008-03-01

    This paper presents the investigations of interfacial interactions and electron-injection mechanisms between cesium nitrate (CsNO3) and different cathode materials. By using ultraviolet and x-ray photoemission spectroscopy, the properties of electronic structures and the interfacial chemistry are studied. According to our results, there exists a phenomenon of electron exchange at the interface results in changes of Aluminum 2s core level binding energy by 1 eV when aluminum was deposited on CsNO3. This means electrons transfer from cathode materials to the surface of CsNO3, forming a strong dipolar field at the interface and reduction of the electron injection barrier. But, in contract, there exists nearly no reaction between CsNO3 and silver cathode. The evidences show that CsNO3 is more effective only with aluminum cathode due to a reaction between Aluminum, Cesium and Nitrogen atoms.

  16. COMPARISON OF SILICA IMMOBILIZED POLY-L-CYSTEINE AND 8-HYDROXYQUINOLINE FOR TRACE METAL CHELATION AND PRECONCENTRATION. (R826694C651)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  17. Water-Soluble 8-Hydroxyquinoline Conjugate of Amino-Glucose As Receptor for La(3+) in HEPES Buffer, on Whatman Cellulose Paper and in Living Cells.

    PubMed

    Areti, Sivaiah; Bandaru, Sateesh; Teotia, Rohit; Rao, Chebrolu P

    2015-12-15

    A water-soluble glucopyranosyl conjugate, L, has been synthesized and characterized by different analytical and spectral techniques. The L has been demonstrated to have switch-on fluorescence enhancement of ∼75 fold in the presence of La(3+) among the nine lanthanide ions studied in the HEPES buffer at pH 7.4. A minimum detection limit of 140 nM (16 ± 2 ppb) was shown by L for La(3+) in the buffer at physiological pH. The utility of L has been demonstrated by showing its sensitivity toward La(3+) on Whatman filter paper strips. The reversible and reusable action of L has been demonstrated by monitoring the fluorescence changes as a function of the addition of La(3+) followed by F(-) and HPO4(2-) ions. The complexation of L by La(3+) was shown by absorption spectra wherein isosbestic behavior was observed. The Job's plot suggests a 2:1 complex between L and La(3+), and the same was supported by ESI-MS. The control molecular study revealed the necessity of hydroxy quinoline and the amine group for La(3+) ion binding and the glyco-moiety to bring water solubility and biocompatibility. The structural features of the [2L+La(3+)] complex were established by DFT computational calculations. The chemo-ensemble, [2L+La(3+)], is shown responsible for providing intracellular fluorescence imaging in HepG2 cells.

  18. The Role of Weak Interactions in the Mechano-induced Single-Crystal-to-Single-Crystal Phase Transition of 8-Hydroxyquinoline-Based Co-crystals.

    PubMed

    Liu, Jie; Liu, Guangfeng; Liu, Yang; Zheng, Xiaoxin; Han, Quanxiang; Ye, Xin; Tao, Xutang

    2016-06-01

    Mechano-induced single-crystal-to-single-crystal (SCSC) phase transitions in crystalline materials that change their properties have received more and more attention. However, there are still too few examples to study molecular-level mechanisms in the mechano-induced SCSC phase transitions, making the systematic and in-depth understanding very difficult. We report that bis-(8-hydroxyquinolinato) palladium(II)-tetracyanoquinodimethane (PdQ2 -TCNQ) and bis-(8-hydroxyquinolinato) copper(II)-tetracyanoquinodimethane (CuQ2 -TCNQ) show very different mechano-response behaviors during the SCSC phase transition. Phase transition in CuQ2 -TCNQ can be triggered by pricking on the crystal surface, while in PdQ2 -TCNQ it can only be induced by applying pressure uniformly over the whole crystal face. The crystallography data and Hirshfeld surface analysis indicate that the weak intra-layer C-H⋅⋅⋅O, C-H⋅⋅⋅N hydrogen bonds and inter-layer stacking interactions determine the feasibility of the SCSC phase transition by mechanical stimuli. Weaker intra-layer interactions and looser inter-layer stacking make the SCSC phase transition occur much more easily in the CuQ2 -TCNQ.

  19. 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.

  20. MODEL FOR NON-EQUILIBRIUM BINDING AND AFFINITY CHROMATOGRAPHY WITH CHARACTERIZATION OF 8-HYDROXYQUINOLINE IMMOBILIZED ON CONTROLLED PORE GLASS USING A FLOW INJECTION SYSTEM WITH A PACKED MICRO-COLUMN. (R826694C651)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  1. Fluorescence in complexes based on quinolines-derivatives: a search for better fluorescent probes.

    PubMed

    Mecca, Carolina Z P; Fonseca, Fernando L A; Bagatin, Izilda A

    2016-11-01

    Quinoline-derived fluorescent complexes were designed; synthesized by the reaction of 5-nitro-8-hydroxyquinoline and 5-chloro-8-hydroxyquinoline with Al(3+), Mg(2+), Zn(2+), and Cd(2+) salts (1-8); and characterized. The (1)H NMR spectra of complexes 1 and 5, containing Al(3+), were consistent with an octahedral structure having approximate D3 symmetry, and the results supported the favored facial isomer (fac). Data for complexes 2-4 and 6-8 supported the formation of tetrahedral structures. Intense luminescence was detected for complexes 5-8, even with the naked eye, as indicated by quantum yield values of 0.087, 0.094, 0.051, and 0.021, respectively. Furthermore, in contrast to 5-nitro-8-hydroxyquinoline, the 5-chloro-8-hydroxyquinoline ligand exhibited bands at different energies depending on the coordinated metal, which supported its potential application in ionic and biological probes, as well as in cell imaging. PMID:27288961

  2. Fluorescence in complexes based on quinolines-derivatives: a search for better fluorescent probes.

    PubMed

    Mecca, Carolina Z P; Fonseca, Fernando L A; Bagatin, Izilda A

    2016-11-01

    Quinoline-derived fluorescent complexes were designed; synthesized by the reaction of 5-nitro-8-hydroxyquinoline and 5-chloro-8-hydroxyquinoline with Al(3+), Mg(2+), Zn(2+), and Cd(2+) salts (1-8); and characterized. The (1)H NMR spectra of complexes 1 and 5, containing Al(3+), were consistent with an octahedral structure having approximate D3 symmetry, and the results supported the favored facial isomer (fac). Data for complexes 2-4 and 6-8 supported the formation of tetrahedral structures. Intense luminescence was detected for complexes 5-8, even with the naked eye, as indicated by quantum yield values of 0.087, 0.094, 0.051, and 0.021, respectively. Furthermore, in contrast to 5-nitro-8-hydroxyquinoline, the 5-chloro-8-hydroxyquinoline ligand exhibited bands at different energies depending on the coordinated metal, which supported its potential application in ionic and biological probes, as well as in cell imaging.

  3. Fluorescence in complexes based on quinolines-derivatives: a search for better fluorescent probes

    NASA Astrophysics Data System (ADS)

    Mecca, Carolina Z. P.; Fonseca, Fernando L. A.; Bagatin, Izilda A.

    2016-11-01

    Quinoline-derived fluorescent complexes were designed; synthesized by the reaction of 5-nitro-8-hydroxyquinoline and 5-chloro-8-hydroxyquinoline with Al3+, Mg2+, Zn2+, and Cd2+ salts (1-8); and characterized. The 1H NMR spectra of complexes 1 and 5, containing Al3+, were consistent with an octahedral structure having approximate D3 symmetry, and the results supported the favored facial isomer (fac). Data for complexes 2-4 and 6-8 supported the formation of tetrahedral structures. Intense luminescence was detected for complexes 5-8, even with the naked eye, as indicated by quantum yield values of 0.087, 0.094, 0.051, and 0.021, respectively. Furthermore, in contrast to 5-nitro-8-hydroxyquinoline, the 5-chloro-8-hydroxyquinoline ligand exhibited bands at different energies depending on the coordinated metal, which supported its potential application in ionic and biological probes, as well as in cell imaging.

  4. A Simplified Experimental Scheme for the Study of Mitosis.

    ERIC Educational Resources Information Center

    Gill, John

    1980-01-01

    A procedure is described for providing preparations of dividing cells from root apical meristems, requiring only inexpensive equipment and minimal experimental skill, and using 8-Hydroxyquinoline and Toluidene-blue as a chromosome stain. The method has been sucessfully tested in schools and yields permanent preparations of adequate quality for…

  5. Insights Into the Solution Crystallization of Oriented Alq3 and Znq2 Microprisms and Nanorods.

    PubMed

    Boulet, Joel; Mohammadpour, Arash; Shankar, Karthik

    2015-09-01

    Optimized solution-based methods to grow high quality micro- and nanocrystals of organic semi-conductors with defined size, shape and orientation are important to a variety of optoelectronic applications. In this context, we report the growth of single crystal micro- and nanostructures of the organic semiconductors Tris(8-hydroxyquinoline)aluminum (Alq3) and bis(8-hydroxyquinoline)zinc (Znq2) terminating in flat crystal planes using a combination of evaporative and antisolvent crystallization. By controlling substrate-specific nucleation and optimizing the conditions of growth, we generate vertically-oriented hexagonal prism arrays of Alq3, and vertical half-disks and sharp-edged rectangular prisms of Znq2. The effect of process variables such as ambient vapour pressure, choice of anti-solvent and temperature on the morphology and crystal habit of the nanostructures were studied and the results of varying them catalogued to gain a better understanding of the mechanism of growth. PMID:26716228

  6. Study on bioactive compounds from Streptomyces sp. ANU 6277.

    PubMed

    Narayana, Kolla J P; Prabhakar, Peddikotla; Vijayalakshmi, Muvva; Venkateswarlu, Yenamandra; Krishna, Palakodety S J

    2008-01-01

    An attempt was made to study the bioactive compounds from a terrestrial Streptomyces sp. ANU 6277 isolated from laterite soil. Four active fractions were recovered from the solvent extracts obtained from the culture broth of five day-old strain. Three bioactive compounds were purified and identified as 3-phenylpropionic acid, anthracene-9,10-quinone and 8-hydroxyquinoline. The components of the partially purified fourth active fraction were analyzed by gas chromatography-mass spectrometry and identified as benzyl alcohol, phenylethyl alcohol and 2H-1, 4-benzoxazin-3 (4H)-one. Four active fractions were screened for antimicrobial activity against Gram-positive and Gram-negative bacteria, and fungi including phytopathogenic, toxigenic and dermatophytic genera. Among these metabolites, 8-hydroxyquinoline exhibited strong antibacterial and antifungal activity as compared to 3-phenylpropionic acid and anthracene-9,10-quinone. PMID:18610654

  7. Study on bioactive compounds from Streptomyces sp. ANU 6277.

    PubMed

    Narayana, Kolla J P; Prabhakar, Peddikotla; Vijayalakshmi, Muvva; Venkateswarlu, Yenamandra; Krishna, Palakodety S J

    2008-01-01

    An attempt was made to study the bioactive compounds from a terrestrial Streptomyces sp. ANU 6277 isolated from laterite soil. Four active fractions were recovered from the solvent extracts obtained from the culture broth of five day-old strain. Three bioactive compounds were purified and identified as 3-phenylpropionic acid, anthracene-9,10-quinone and 8-hydroxyquinoline. The components of the partially purified fourth active fraction were analyzed by gas chromatography-mass spectrometry and identified as benzyl alcohol, phenylethyl alcohol and 2H-1, 4-benzoxazin-3 (4H)-one. Four active fractions were screened for antimicrobial activity against Gram-positive and Gram-negative bacteria, and fungi including phytopathogenic, toxigenic and dermatophytic genera. Among these metabolites, 8-hydroxyquinoline exhibited strong antibacterial and antifungal activity as compared to 3-phenylpropionic acid and anthracene-9,10-quinone.

  8. SEPARATION PROCESS USING COMPLEXING AND ADSORPTION

    DOEpatents

    Spedding, J.H.; Ayers, J.A.

    1958-06-01

    An adsorption process is described for separating plutonium from a solution of neutron-irradiated uranium containing ions of a compound of plutonium and other cations. The method consists of forming a chelate complex compound with plutoniunn ions in the solution by adding a derivative of 8- hydroxyquinoline, which derivative contains a sulfonic acid group, and adsorbing the remaining cations from the solution on a cation exchange resin, while the complexed plutonium remains in the solution.

  9. Unusual red shift of the sensor while detecting the presence of Cd2+ in aqueous environment.

    PubMed

    Sarkar, Santu; Shunmugam, Raja

    2013-08-14

    A norbornene derived 8-hydroxyquinoline (N8HQ) is designed and synthesized. A "turn-on" ratiometric fluorescent response is observed for Cd(2+) in aqueous solution upon binding with N8HQ with a characteristic huge red shift of 164 nm. A lowest detection limit of 1.6 nM of Cd(2+) is achieved in the presence of other heavy metals.

  10. Copper(I)-catalyzed aryl bromides to form intermolecular and intramolecular carbon-oxygen bonds.

    PubMed

    Niu, Jiajia; Guo, Pengran; Kang, Juntao; Li, Zhigang; Xu, Jingwei; Hu, Shaojing

    2009-07-17

    A highly efficient Cu-catalyzed C-O bond-forming reaction of alcohol and aryl bromides has been developed. This transformation was realized through the use of copper(I) iodide as a catalyst, 8-hydroxyquinoline as a ligand, and K(3)PO(4) as a base. A variety of functionalized substrates were found to react under these reaction conditions to provide products in good to excellent yields.

  11. Unusual red shift of the sensor while detecting the presence of Cd2+ in aqueous environment.

    PubMed

    Sarkar, Santu; Shunmugam, Raja

    2013-08-14

    A norbornene derived 8-hydroxyquinoline (N8HQ) is designed and synthesized. A "turn-on" ratiometric fluorescent response is observed for Cd(2+) in aqueous solution upon binding with N8HQ with a characteristic huge red shift of 164 nm. A lowest detection limit of 1.6 nM of Cd(2+) is achieved in the presence of other heavy metals. PMID:23879449

  12. The effect of electron donating and withdrawing groups on the morphology and optical properties of Alq3

    NASA Astrophysics Data System (ADS)

    Duvenhage, M. M.; Visser, H. G.; Ntwaeaborwa, O. M.; Swart, H. C.

    2014-04-01

    By adding electron donating (EDG) and withdrawing groups (EWG) to the Tris-(8-hydroxyquinoline) aluminum (Alq3) molecule, the emission color can be tuned. In this study the effect of EDG and EWG on the morphology and optical properties of Alq3 were investigated. Alq3 powders was synthesized with an EDG (-CH3) substituted at positions 5 and 7 ((5,7-dimethyl-8-hydroxyquinoline) aluminum) and EWG (-Cl) at position 5 ((5-chloro-8-hydroxyquinoline) aluminum). A broad absorption band at ~380 nm was observed for Alq3. The bands of the substituted samples were red-shifted. The un-substituted Alq3 showed a high intensity emission peak at 500 nm. The -Cl and -CH3 samples showed a red-shift of 33 and 56 nm respectively. The morphology of the samples was studied using a scanning electron microscope. The photo degradation of the samples was also investigated and the dimethyl sample shows the least degradation to the UV irradiation over the 24 h of continuous irradiation.

  13. Bovine liver dihydropyrimidine amidohydrolase: purification, properties, and characterization as a zinc metalloenzyme.

    PubMed

    Brooks, K P; Jones, E A; Kim, B D; Sander, E G

    1983-10-15

    Beef liver dihydropyrimidine amidohydrolase has been purified to homogeneity using both an electrophoretic and a hydrophobic chromatographic method. The enzyme is a tetramer with a molecular weight of 226,000 g mol-1, a subunit molecular weight of 56,500 g mol-1, and contains 4 mol of tightly bound (Ks greater than or equal to 1.33 X 10(9) M-1) Zn2+ per mole of active enzyme. The enzyme appears to be a true Zn2+ metalloenzyme because there exists a direct proportionality between enrichment of Zn2+ and active enzyme during purification, there is an almost quantitative relationship between the loss of both enzyme activity and Zn2+ during 8-hydroxyquinoline-5-sulfonic acid treatment to form apoenzyme, Zn2+ and Co2+ reactivate dipicolinic acid-inhibited enzyme, and saturating concentrations of a substrate, dihydrothymine, protect against 8-hydroxyquinoline-5-sulfonic acid inhibition. EDTA does not inhibit the enzyme; however, 8-hydroxyquinoline-5-sulfonic acid, o-phenanthroline, and 2,6-dipicolinic acid cause a time-dependent loss in activity which follows pseudo-first-order kinetics. Analysis of the resulting kinetic data for these three chelators indicates that the reaction pathway involves the formation of an enzyme-Zn2+-chelator ternary complex which then dissociates to form apoenzyme and a Zn2+-chelator complex. Like other Zn2+ metalloenzymes, the enzyme is inhibited by a number of substituted sulfonamides. In the case of p-nitrobenzenesulfonamide, this inhibition is competitive in nature. Using the purified enzyme, kinetic constants were determined for a variety of dihydropyrimidines, ureidocarboxylic acids, and hydantoin substrates. Normal hyperbolic kinetics were observed for the hydrolysis of the cyclic compounds, but the cyclization of the ureidoacids showed biphasic kinetics and different values of Km can be estimated at either high or low concentrations of these substrates.

  14. Xenobiotics enhance laccase activity in alkali-tolerant γ-proteobacterium JB

    PubMed Central

    Singh, Gursharan; Batish, Mona; Sharma, Prince; Capalash, Neena

    2009-01-01

    Various genotoxic textile dyes, xenobiotics, substrates (10 µM) and agrochemicals (100 µg/ml) were tested for enhancement of alkalophilic laccase activity in γ-proteobacterium JB. Neutral Red, Indigo Carmine, Naphthol Base Bordears and Sulphast Ruby dyes increased the activity by 3.7, 2.7, 2.6 and 2.3 fold respectively. Xenobiotics/substrates like p-toluidine, 8-hydroxyquinoline and anthracine increased it by 3.4, 2.8 and 2.3 fold respectively. Atrazine and trycyclozole pesticides enhanced the activity by 1.95 and 1.5 fold respectively. PMID:24031313

  15. New reagent system for spectrophotometric determination of benzidine

    SciTech Connect

    Upadhyay, S.; Gupta, V.K.

    1985-09-01

    The present method is based on the diazotization of benzidine and its subsequent coupling with 8-hydroxyquinoline. The red colored dye so formed in alkaline medium is extracted into 3-methyl-1-butanol. The Beer's law is obeyed in the range of 0.03 to 0.30 ..mu..g/mL. The molar absorptivity and Sandell's sensitivity are 6.4 x 10/sup 4/ L/mol/cm and 0.0026 ..mu..g/cm/sup 2/ respectively. Other reaction conditions and analytical parameters were also studied. The present method has been tested for the determination of benzidine in urine.

  16. Xenobiotics enhance laccase activity in alkali-tolerant γ-proteobacterium JB.

    PubMed

    Singh, Gursharan; Batish, Mona; Sharma, Prince; Capalash, Neena

    2009-01-01

    Various genotoxic textile dyes, xenobiotics, substrates (10 µM) and agrochemicals (100 µg/ml) were tested for enhancement of alkalophilic laccase activity in γ-proteobacterium JB. Neutral Red, Indigo Carmine, Naphthol Base Bordears and Sulphast Ruby dyes increased the activity by 3.7, 2.7, 2.6 and 2.3 fold respectively. Xenobiotics/substrates like p-toluidine, 8-hydroxyquinoline and anthracine increased it by 3.4, 2.8 and 2.3 fold respectively. Atrazine and trycyclozole pesticides enhanced the activity by 1.95 and 1.5 fold respectively.

  17. The determination of aluminum, copper, iron, and lead in glycol formulations by atomic absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Initial screening tests and the results obtained in developing procedures to determine Al, Cu, Fe, and Pb in glycol formulations are described. Atomic absorption completion was selected for Cu, Fe and Pb, and after comparison with emission spectroscopy, was selected for Al also. Before completion, carbon, iron, and lead are extracted with diethyl dithio carbamate (DDC) into methyl isobutyl ketone (MIBK). Aluminum was also extracted into MIBK using 8-hydroxyquinoline as a chelating agent. As little as 0.02 mg/l carbon and 0.06 mg/l lead or iron may be determined in glycol formulations. As little as 0.3 mg/l aluminum may be determined.

  18. Hydroxamate-based iron chelators: combinatorial syntheses of desferrioxamine B analogues and evaluation of binding affinities.

    PubMed

    Poreddy, Amruta R; Schall, Otto F; Osiek, Todd A; Wheatley, James R; Beusen, Denise D; Marshall, Garland R; Slomczynska, Urszula

    2004-01-01

    This article describes the solid-phase combinatorial methods developed for the synthesis of polyhydroxamate-based siderophores. This strategy was applied to generate several libraries of structural DFO (1a) analogues that include DFO variants, non-amide analogues, C-terminal modified analogues, reverse-amide analogues, and hybrid analogues. To assess the relative iron-binding affinities of these compounds, a high-throughput spectrophotometric screening method based on competition with 8-hydroxyquinoline-5-sulfonic acid was developed. Some of the promising candidates containing various terminal functional groups were identified and prepared on large scale to enable future studies in animal models for iron-overload diseases.

  19. Quinobene, a new potent anti-HIV agent.

    PubMed

    Gruszecka-Kowalik, E; Haugwitz, R D; Zalkow, L H

    1992-09-30

    A simple synthesis of the sulfonated azo dye Quinobene (3) and its derivatives, as well as the results of their evaluation in anti-HIV screening have been described. Thus, reacting the diazonium salt of 4,4'-diaminostilbene-2,2'-disulfonic acid with 8-hydroxyquinoline-5-sulfonic acid yielded the readily isolable title compound. The lithium and tetramethylammonium salts of Quinobene and its complexes with Cu(II), Zn(II), Mg(II) were also prepared. In vitro tests showed considerable activity of these compounds against HIV-1.

  20. High-performance liquid chromatographic separation and indirect fluorescence detection of thiols.

    PubMed

    Pelletier, Sarah; Lucy, Charles A

    2002-10-01

    A fluorescent post-column reaction detection scheme has been devised for selective determination of thiols. The post-column reagent is 40 microM Cd2+ and 100 microM 8-hydroxyquinoline-5-sulfonic acid (HQS) in non-complexing buffer at pH 10. HQS complexes Cd2+ to form a fluorescent product. Thiols in the HPLC effluent compete for complexation of the Cd2+, resulting in a decrease in the fluorescence response. Detection limits of 0.2 microM (0.04 ppm) are achieved for cysteine, homocysteine and glutathione in a 5 min separation. Recoveries from spiked synthetic urine samples are 87-120%.

  1. [Study on fluorescent properties and application of the new reagent DCOBAQS with aluminium].

    PubMed

    Wu, F; Haung, J

    2001-02-01

    A new fluorometric method is reported for the determination of aluminium, based on the complex forming of 7-[(2,4-dicarboxymethyl-5-carboxybenezene)azo]-8-hydroxyquinoline-5-sulfonic (DCOBAQS) with aluminium. The complex was formed at pH 5.54 with lambda ex/lambda em = 510 nm/572 nm. A better line relationship curve was obtained over the range of 0-0.04 microgram.mL-1 Al(III), and the detection limit for Al(III) is 0.557 ng.mL-1. The method is applied to determination aluminium in tea with satisfactory results.

  2. Determination of picomolar levels of cobalt in seawater by flow injection analysis with chemiluminescence detection

    SciTech Connect

    Sakamoto-Arnold, C.M.; Johnson, K.S.

    1987-07-15

    Flow injection analysis (FIA) was used to automate the determination of cobalt in seawater by the Co-enhanced chemiluminescent oxidation of gallic acid in alkaline hydrogen peroxide. A preconcentration/separation step in the FIA manifold with an in-line column of immobilized 8-hydroxyquinoline was included to separate the Co from alkaline-earth ions. One sample analysis takes 8 min, including the 4-min sample load period. The detection limit is approximately 8 pM. The average standard deviation of replicate analyses at sea of 80 samples was +/- 5%. The method was tested and intercalibrated on samples collected off the California coast.

  3. ELECTRICAL PROPERTIES OF POLYSTYRENE MATRIX DOPED BY GOLD NANOPARTICLES AND 8HQ

    SciTech Connect

    Scaldaferri, R.; Salzillo, G.; Pepe, G. P.; Barra, M.; Pagliarulo, V.; Borriello, A.; Fusco, L.

    2008-08-28

    We explored the modification of polymeric film conductivity by changing the conducting filler percentage in the frame of the percolation theory. The polymeric film is a polystyrene (PS) matrix, while the fillers are gold nanoparticles capped with 1-dodecanethiol (Au-DT NPs) and small conjugated molecules 8- hydroxyquinoline (8HQ). Experimental results show, that increasing the Au- DT and 8HQ wt%, film conductivity increases by up to three orders of magnitude due to charge transfer in the 3D network composed by Au- DT NPs and 8HQ.

  4. Determination of trace amounts of molybdenum in plant tissue by solvent extraction-atomic-absorption and direct-current plasma emission spectrometry.

    PubMed

    Lajunen, L H; Kubin, A

    1986-03-01

    Methods are presented for determination of molybdenum in plant tissue by flame and graphite-furnace atomic-absorption spectrometry and direct-current argon-plasma emission spectrometry. The samples are digested in HNO(3)-H(2)SO(4)-HC1O(4) mixture, and Mo is separated and concentrated by chelation and extraction. Three organic solvents (methyl isobutyl ketone, di-isobutyl ketone and isoamyl alcohol) and two ligands (8-hydroxyquinoline and toluene-3,4-dithiol) were studied. The procedure were tested on pine needle and birch leaf samples. PMID:18964076

  5. Separation of Betti Reaction Product Enantiomers: Absolute Configuration and Inhibition of Botulinum Neurotoxin A

    PubMed Central

    2011-01-01

    The racemic product of the Betti reaction of 5-chloro-8-hydroxyquinoline, benzaldehyde, and 2-aminopyridine was separated by chiral HPLC to determine which enantiomer inhibited botulinum neurotoxin serotype A. When the enantiomers unexpectedly proved to have comparable activity, the absolute structures of (+)-(R)-1 and (−)-(S)-1 were determined by comparison of calculated and observed circular dichroism spectra. Molecular modeling studies were undertaken in an effort to understand the observed bioactivity and revealed different ensembles of binding modes, with roughly equal binding energies, for the two enantiomers. PMID:22102940

  6. Highly sensitive heavy metal ion detection using AlQ3 microwire functionalized QCM

    NASA Astrophysics Data System (ADS)

    Can, Nursel; Aǧar, Meltem; Altındal, Ahmet

    2016-03-01

    Tris(8-hydroxyquinoline) aluminum (Alq3) microwires was successfully synthesized for the fabrication of Alq3 microwires-coated QCM sensors to detect the heavy metal ions in aqueous solution. AT-cut quartz crystal microbalance (QCM) of 10 MHz fundamental resonance frequency having gold electrodes were used as transducers. Typical measuring cycle consisted of repeated flow of target measurands through the flow cell and subsequent washing to return the baseline. The QCM results indicated that the Alq3 microwires exhibit excellent sensitivity, stability and short response-recovery time, which are much attractive for the development of portable and highly sensitive heavy metal ion sensors in water samples.

  7. Structural properties of Alq3 nanocrystals prepared by physical vapor deposition and facile solution method

    NASA Astrophysics Data System (ADS)

    Xie, Wanfeng; Pang, Zhiyong; Fan, Jihui; Song, Hui; Jiang, Feng; Yuan, Huimin; Li, Jianfei; Ji, Ziwu; Han, Shenghao

    2015-09-01

    Tris(8-hydroxyquinoline) aluminum (Alq3) nanostructures are promising materials for nanooptoelectronic devices and molecular spintronics. In this paper, we report Alq3 nanocrystals prepared by both physical vapor deposition (PVD) and facile solution method. The transmission electron microscopy (TEM) and high resolution scanning electron microscope (SEM) measurements show that the Alq3 nanomaterials prepared by PVD technique are ɛ-Alq3 nanoflowers, while the Alq3 nanostructures prepared by solution method are α-Alq3 nanorods. Our experiments indicate that the α-Alq3 nanomaterials prepared by using solution method are more suitable for the fabrication of molecular spintronic devices than that of PVD method.

  8. Tailoring the energy level alignment at the Co/Alq{sub 3} interface by controlled cobalt oxidation

    SciTech Connect

    Haag, Norman; Steil, Sabine; Großmann, Nicolas; Fetzer, Roman; Cinchetti, Mirko; Aeschlimann, Martin

    2013-12-16

    We have studied the influence of oxygen exposure at the prototypical interface between cobalt and the organic semiconductor tris(8-hydroxyquinoline)aluminum (III) (Alq{sub 3}) by photoemission spectroscopy. We find that oxidation of the cobalt leads to a gradual suppression of hybrid interface states, to a progressive change in the work function and to a continuous energetic shift of the molecular orbitals towards higher binding energies. Based on these observations, we propose controlled oxidation of the ferromagnetic electrode as an easy and effective possibility to tune the performance of organic spintronics devices.

  9. Organic transformations catalyzed by methylrhenium trioxide

    SciTech Connect

    Zhu, Z.

    1995-11-01

    Methylrhenium trioxide (MTO), CH{sub 3}ReO{sub 3}, was first prepared in 1979. MTO forms stable or unstable adducts with electron-rich ligands, such as amines (quinuclidine, 1,4-diazabicyclo-octane, pyridine, aniline, 2,2{prime}-bipyridine), alkynes, olefins, 1,2-diols, catechols, hydrogen peroxide, water, thiophenols, 1,2-dithiols, triphenylphosphine, 2-aminophenols, 2-aminothiophenols, 8-hydroxyquinoline and halides (Cl-, Br-, I-). After coordination, different further reactions will occur for different reagents. Reactions described in this report include the dehydration of alcohols, direct amination of alcohols, activation of hydrogen peroxide, oxygen transfer, and decomposition of ethyl diazoacetate.

  10. Use of hydrophobic constants of molecular fragments for characterizing analytical systems

    SciTech Connect

    Tselik, E.I.; Polvektov, N.S.

    1985-06-10

    The authors attempt to clarify the applicability of the proposed hydrophobicity parameters to a description of the behavior of complex compounds with organic ligands in extractional systems, and to establish quantitative relationships between the properties of the complex and hydrophobicity of the ligand. It was found that the stability constants of the ionic associates of lanthanum, neodymium, and erbium with certain derivatives of salicylic acid, dihalogenated derivatives of 8-hydroxyquinoline, and Rhodamine B correlate with the hydrophobicity of the ligands. The quantitative expressions of these serve as empirical hydrophobic constants of molecular fragments of organic compounds.

  11. (Metal-Organic Framework)-Polyaniline sandwich structure composites as novel hybrid electrode materials for high-performance supercapacitor

    NASA Astrophysics Data System (ADS)

    Guo, ShuaiNan; Zhu, Yong; Yan, YunYun; Min, YuLin; Fan, JinChen; Xu, QunJie; Yun, Hong

    2016-06-01

    Carbonized Zn-(Metal-Organic Framework)MOF- polyaniline composites for high performance of supercapacitor have been developed from zinc acetate, 8-Hydroxyquinoline, and aniline via a simple process. The as-synthesized product has been characterized by X-ray powder diffraction (XRD), Scanning electron microscopy(SEM), Fourier transform infrared spectra (FT-IR), Transmission electron microscope (TEM). The electrochemical properties of carbonized Zn-MOF/polyaniline electrode were investigated by current charge-discharge and cyclic voltammetry. The specific capacitance of MOF/PANI has been approach to be as high as 477 F g-1 at a current density of 1 A g-1.

  12. New materials for organic light-emitting diodes

    SciTech Connect

    Jacobs, S.J.; Pollagi, T.P.; Sinclair, M.B.; Scurlock, R.D.; Ogilby, P.R.

    1995-12-01

    We have investigated the performance of a class of heterocycles, 5, 10-dihetera-5,10-dihydroindeno[3,2b]indenes, as hole transport agents in simple double heterostructure organic light-emitting diodes with tris(8-hydroxyquinoline)aluminum (Alq). The best of these materials, 5,10-dihydroindolo[3,2b]indole, yields devices with luminance and lifetimes comparable to those obtained using N,N{prime}-di-(3-methylphenyl)-N,N{prime}diphenyl-4,4{prime}-diaminobiphenyl (TPD) as a hole transporting material.

  13. Exciton coupling of surface complexes on a nanocrystal surface.

    PubMed

    Xu, Xiangxing; Ji, Jianwei; Wang, Guan; You, Xiaozeng

    2014-08-25

    Exciton coupling may arise when chromophores are brought into close spatial proximity. Herein the intra-nanocrystal exciton coupling of the surface complexes formed by coordination of 8-hydroxyquinoline to ZnS nanocrystals (NCs) is reported. It is studied by absorption, photoluminescence (PL), PL excitation (PLE), and PL lifetime measurements. The exciton coupling of the surface complexes tunes the PL color and broadens the absorption and PLE windows of the NCs, and thus is a potential strategy for improving the light-harvesting efficiency of NC solar cells and photocatalysts.

  14. Synthesis, characterization and antimicrobial activities of mixed ligand transition metal complexes with isatin monohydrazone Schiff base ligands and heterocyclic nitrogen base

    NASA Astrophysics Data System (ADS)

    Devi, Jai; Batra, Nisha

    2015-01-01

    Mixed ligand complexes of Co(II), Ni(II), Cu(II) and Zn(II) with various uninegative tridentate ligands derived from isatin monohydrazone with 2-hydroxynapthaldehyde/substituted salicylaldehyde and heterocyclic nitrogen base 8-hydroxyquinoline have been synthesized and characterized by elemental analysis, conductometric studies, magnetic susceptibility and spectroscopic techniques (IR, UV-VIS, NMR, mass and ESR). On the basis of these characterizations, it was revealed that Schiff base ligands existed as monobasic tridentate ONO bonded to metal ion through oxygen of carbonyl group, azomethine nitrogen and deprotonated hydroxyl oxygen and heterocyclic nitrogen base 8-hydroxyquinoline existed as monobasic bidentate ON bonded through oxygen of hydroxyl group and nitrogen of quinoline ring with octahedral or distorted octahedral geometry around metal ion. All the compounds have been tested in vitro against various pathogenic Gram positive bacteria, Gram negative bacteria and fungi using different concentrations (25, 50, 100, 200 μg/mL) of ligands and their complexes. Comparative study of antimicrobial activity of ligands, and their mixed complexes indicated that complexes exhibit enhanced activity as compared to free ligands and copper(II) Cu(LIV)(Q)ṡH2O complex was found to be most potent antimicrobial agent.

  15. Synthesis, characterization and antimicrobial activities of mixed ligand transition metal complexes with isatin monohydrazone Schiff base ligands and heterocyclic nitrogen base.

    PubMed

    Devi, Jai; Batra, Nisha

    2015-01-25

    Mixed ligand complexes of Co(II), Ni(II), Cu(II) and Zn(II) with various uninegative tridentate ligands derived from isatin monohydrazone with 2-hydroxynapthaldehyde/substituted salicylaldehyde and heterocyclic nitrogen base 8-hydroxyquinoline have been synthesized and characterized by elemental analysis, conductometric studies, magnetic susceptibility and spectroscopic techniques (IR, UV-VIS, NMR, mass and ESR). On the basis of these characterizations, it was revealed that Schiff base ligands existed as monobasic tridentate ONO bonded to metal ion through oxygen of carbonyl group, azomethine nitrogen and deprotonated hydroxyl oxygen and heterocyclic nitrogen base 8-hydroxyquinoline existed as monobasic bidentate ON bonded through oxygen of hydroxyl group and nitrogen of quinoline ring with octahedral or distorted octahedral geometry around metal ion. All the compounds have been tested in vitro against various pathogenic Gram positive bacteria, Gram negative bacteria and fungi using different concentrations (25, 50, 100, 200 μg/mL) of ligands and their complexes. Comparative study of antimicrobial activity of ligands, and their mixed complexes indicated that complexes exhibit enhanced activity as compared to free ligands and copper(II) Cu(LIV)(Q)⋅H2O complex was found to be most potent antimicrobial agent. PMID:25129626

  16. Electrochemistry and spectroelectrochemistry of bioactive hydroxyquinolines: a mechanistic study.

    PubMed

    Sokolová, Romana; Nycz, Jacek E; Ramešová, Šárka; Fiedler, Jan; Degano, Ilaria; Szala, Marcin; Kolivoška, Viliam; Gál, Miroslav

    2015-05-21

    The oxidation mechanism of selected hydroxyquinoline carboxylic acids such as 8-hydroxyquinoline-7-carboxylic acid (1), the two positional isomers 2-methyl-8-hydroxyquinoline-7-carboxylic acid (3) and 2-methyl-5-hydroxyquinoline-6-carboxylic acid (4), as well as other hydroxyquinolines were studied in aprotic environment using cyclic voltammetry, controlled potential electrolysis, in situ UV-vis and IR spectroelectrochemistry, and HPLC-MS/MS techniques. IR spectroelectrochemistry showed that oxidation unexpectedly proceeds together with protonation of the starting compound. We proved that the nitrogen atom in the heterocycle of hydroxyquinolines is protonated during the apparent 0.7 electron oxidation process. This was rationalized by the autodeprotonation reaction by another two starting molecules of hydroxyquinoline, so that the overall oxidation mechanism involves two electrons and three starting molecules. Both the electrochemical and spectroelectrochemical results showed that the oxidation mechanism is not influenced by the presence of the carboxylic group in the chemical structure of hydroxyquinolines, as results from oxidation of 2,7-dimethyl-5-hydroxyquinoline (6). In the presence of a strong proton acceptor such as pyridine, the oxidation ECEC process involves two electrons and two protons per one molecule of the hydroxyquinoline derivative. The electron transfer efficiency of hydroxyquinolines in biosystems may be related to protonation of biocompounds containing nitrogen bases. Molecular orbital calculations support the experimental findings. PMID:25915694

  17. Zinc deficiency and the Euglena gracilis chromatin: formation of an alpha-amanitin-resistant RNA polymerase II.

    PubMed

    Falchuk, K H; Mazus, B; Ber, E; Ulpino-Lobb, L; Vallee, B L

    1985-05-01

    Both the single DNA-dependent RNA polymerase found in zinc-deficient (-Zn) Euglena gracilis and the RNA polymerase III from zinc-sufficient (+Zn) cells have been isolated by methods previously used to purify polymerases I and II [Falchuk, K. H., Mazus, B., Ulpino, L., & Vallee, B. L. (1976) Biochemistry 15, 4468; Falchuk, K. H., Mazus, B., Ulpino, L., & Vallee, B. L. (1977) Biochem. Biophys. Res. Commun. 74, 1206]. Like class II polymerases, the enzyme from -Zn organisms elutes from DNA-cellulose and phosphocellulose with 0.6 M NaCl and 0.35 M NH4Cl, respectively. It is inhibited by 8-hydroxyquinoline, 8-hydroxyquinoline-5-sulfonic acid, alpha,alpha'-bipyridyl, dipicolinic acid, and 1,10-phenanthroline (OP); 4,7-phenanthroline, the nonchelating analogue, does not inhibit. The pKI(OP) of this enzyme is identical with that of polymerase II but distinct from those of polymerases I and III. Elemental analysis confirms that zinc is the functional metal while copper, manganese, iron, and magnesium are absent. However, the -Zn enzyme is at least 4 orders of magnitude more resistant to alpha-amanitin (alpha-A) than the class II polymerase. Further, its response to alpha-A is unlike that of either polymerase I or polymerase III. Thus, -Zn cells contain a single, alpha-amanitin-resistant (alpha-Ar) RNA polymerase, whose behavior otherwise resembles that of the alpha-amanitin-sensitive polymerase II.

  18. Euglena gracilis DNA dependent RNA polymerase II: a zinc metalloenzyme.

    PubMed

    Falchuk, K H; Mazus, B; Ulpino, L; Vallee, B L

    1976-10-01

    Zinc is essential for cellular proliferation. Zinc deficiency of Euglena gracilis results in arrest of cell division and deranges nucleic acid and protein metabolism pointing to a decisive role of zinc in transcription and translation. We have, therefore, investigated the role of zinc in the function of the DNA-dependent RNA polymerases of this organism. Two RNA polymerases from zinc sufficient organisms were purified first by affinity chromatography on a DNA cellulose column and subsequently separated on diethylaminoethyl (DEAE)-Sephadex A-25. The two fractions were characterized as polymerase I and II by their elution pattern from DEAE-Sephadex and sensitivity to alpha-amanitin. RNA polymerase II has a provisional molecular weight of 700 000 and contains an average of 2.2 g=atoms of zinc per mol of enzyme, but not Mn, Cu, or Fe, as measured by microwave emission spectroscopy. Chelating agents, such as 1,10-phenanthroline, 8-hydroxyquinoline, 8-hydroxyquinoline-5-sulfonic acid, and lomofungin, inhibit activity. In contrast, the nonchelating analogues, 1,7-and 4,7-phenanthroline, do not affect activity. Inhibition by 1,10-phenanthroline is instantaneous and fully reversible by dilution. 1,10-Phenanthroline also inhibits RNA polymerase I, suggesting a role of zinc in its function. The demonstration that RNA polymerase II is a zinc enzyme indicates the involvement of zinc in eukaryotic RNA synthesis and serves as a further basis for the definition of the role of this element in eukaryotic cell growth, division, and differentiation.

  19. The effect of various metal ions and chelating agents on the formation of noncovalently and covalently linked IgM polymers.

    PubMed

    Eskeland, T

    1977-01-01

    The influence of various concentrations of Mg2+, Ca2+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, EDTA, or 8-hydroxyquinoline-5-sulfonic acid on the formation in vitro of polymeric IgM from reduced and dissociated IgM has been investigated. 4-200muM Zn, Cd, or Hg ions in the dialysis buffer used for reassociation resulted in the formation of a homogeneous polymer peak sedimenting as 19S IgM, whereas the other metal ions resulted in the formation of polymers sedimenting mostly as tetramers, pentamers (19S IgM), and hexamers. Dialysis in the presence of 1 and 3mM EDTA or 8-hydroxyquinoline-5-sulfonic acid gave slight polymer formation; 10 mM of the agents gave none. Ca, Mg, Fe, Ni, Zn, Cd, or Hg ions regularly gave only noncovalently linked polymers, whereas Cu ions in particular, but also Co and, to a minor extent, Mn ions catalyzed the formation of covalently linked polymers. Experiments performed with Mg, Ca, Ni, and Zn ions or with Cu and Zn ions in the same buffer during reassociation showed that Zn ions inhibit the effect of the other ions on polymer assembly and covalent stabilization.

  20. Liposomes in silicosis investigations.

    PubMed

    Erdogdu, G; Hasirci, V N

    1983-09-01

    The effects of quartz and sodium metasilicate on liposomes were studied in order to understand the mechanism of silicosis. 8-Hydroxyquinoline-5-sulfonic acid was tested for its in situ silicosis-prevention capacity. Two types of liposomes--(A) those incorporating cholesterol and (B) those without cholesterol--were used. The tests consisted of measuring permeability changes caused by the above-mentioned chemicals. Permeabilities were found to depend on membrane composition. Tests on quartz action led us to the conclusion that liposomes of this composition did not simulate the erythrocytes very well. It was also observed that absence or presence of cholesterol and the mode of contact altered the effect of quartz. Silicate destabilized type A liposomes, but this was less than that caused by quartz. This was explained by the concentration of monosilicic acid that dissolves out from quartz and silicate. When quartz was pretreated with the preventive, the type A liposomes were stabilized, but a slight destabilizing effect was observed on type B. 8-Hydroxyquinoline-5-sulfonic acid augmented the destabilizing effect of silicate, whereas it decreased the hemolytic activity of uncoated quartz, indicating a preventive potential in in vivo.

  1. Liposomes in silicosis investigations.

    PubMed Central

    Erdogdu, G; Hasirci, V N

    1983-01-01

    The effects of quartz and sodium metasilicate on liposomes were studied in order to understand the mechanism of silicosis. 8-Hydroxyquinoline-5-sulfonic acid was tested for its in situ silicosis-prevention capacity. Two types of liposomes--(A) those incorporating cholesterol and (B) those without cholesterol--were used. The tests consisted of measuring permeability changes caused by the above-mentioned chemicals. Permeabilities were found to depend on membrane composition. Tests on quartz action led us to the conclusion that liposomes of this composition did not simulate the erythrocytes very well. It was also observed that absence or presence of cholesterol and the mode of contact altered the effect of quartz. Silicate destabilized type A liposomes, but this was less than that caused by quartz. This was explained by the concentration of monosilicic acid that dissolves out from quartz and silicate. When quartz was pretreated with the preventive, the type A liposomes were stabilized, but a slight destabilizing effect was observed on type B. 8-Hydroxyquinoline-5-sulfonic acid augmented the destabilizing effect of silicate, whereas it decreased the hemolytic activity of uncoated quartz, indicating a preventive potential in in vivo. Images FIGURE 1. PMID:6416823

  2. Translational downregulation of HSP90 expression by iron chelators in neuroblastoma cells.

    PubMed

    Sidarovich, Viktoryia; Adami, Valentina; Gatto, Pamela; Greco, Valentina; Tebaldi, Toma; Tonini, Gian Paolo; Quattrone, Alessandro

    2015-01-01

    Iron is an essential cellular nutrient, being a critical cofactor of several proteins involved in cell growth and replication. Compared with normal cells, neoplastic cells have been shown to require a greater amount of iron, thus laying the basis for the promising anticancer activity of iron chelators. In this work, we evaluated the effects of molecules with iron chelation activity on neuroblastoma (NB) cell lines. Of the 17 iron chelators tested, six reduced cell viability of two NB cell lines with an inhibition of growth of 50% below 10 µM; four of the six molecules-ciclopirox olamine (CPX), piroctone, 8-hydroxyquinoline, and deferasirox-were also shown to efficiently chelate intracellular iron within minutes after addition. Effects on cell viability of one of the compounds, CPX, were indeed dependent on chelation of intracellular iron and mediated by both G0/G1 cell cycle block and induction of apoptosis. By combined transcriptome and translatome profiling we identified early translational downregulation of several members of the heat shock protein group as a specific effect of CPX treatment. We functionally confirmed iron-dependent depletion of HSP90 and its client proteins at pharmacologically achievable concentrations of CPX, and we extended this effect to piroctone, 8-hydroxyquinoline, and deferasirox. Given the documented sensitivity of NB cells to HSP90 inhibition, we propose CPX and other iron chelators as investigational antitumor agents in NB therapy. PMID:25564462

  3. Graphite furnace atomic absorption spectrometric detection of vanadium in water and food samples after solid phase extraction on multiwalled carbon nanotubes.

    PubMed

    Wadhwa, Sham Kumar; Tuzen, Mustafa; Gul Kazi, Tasneem; Soylak, Mustafa

    2013-11-15

    Vanadium(V) ions as 8-hydroxyquinoline chelates were loaded on multiwalled carbon nanotubes (MWNTs) in a mini chromatographic column. Vanadium was determined by graphite furnace atomic absorption spectrometry (GFAAS). Various analytical parameters including pH of the working solutions, amounts of 8-hydroxyquinoline, eluent type, sample volume, and flow rates were investigated. The effects of matrix ions and some transition metals were also studied. The column can be reused 250 times without any loss in its sorption properties. The preconcentration factor was found as 100. Detection limit (3 s) and limit of quantification (10 s) for the vanadium in the optimal conditions were observed to be 0.012 µg L(-1) and 0.040 μg L(-1), respectively. The capacity of adsorption was 9.6 mg g(-1). Relative standard deviation (RSD) was found to be 5%. The validation of the method was confirmed by using NIST SRM 1515 Apple leaves, NIST SRM 1570a Spinach leaves and GBW 07605 Tea certified reference materials. The procedure was applied to the determination of vanadium in tap water and bottled drinking water samples. The procedure was also successfully applied to microwave digested food samples including black tea, coffee, tomato, cabbage, zucchini, apple and chicken samples.

  4. Electrochemistry and spectroelectrochemistry of bioactive hydroxyquinolines: a mechanistic study.

    PubMed

    Sokolová, Romana; Nycz, Jacek E; Ramešová, Šárka; Fiedler, Jan; Degano, Ilaria; Szala, Marcin; Kolivoška, Viliam; Gál, Miroslav

    2015-05-21

    The oxidation mechanism of selected hydroxyquinoline carboxylic acids such as 8-hydroxyquinoline-7-carboxylic acid (1), the two positional isomers 2-methyl-8-hydroxyquinoline-7-carboxylic acid (3) and 2-methyl-5-hydroxyquinoline-6-carboxylic acid (4), as well as other hydroxyquinolines were studied in aprotic environment using cyclic voltammetry, controlled potential electrolysis, in situ UV-vis and IR spectroelectrochemistry, and HPLC-MS/MS techniques. IR spectroelectrochemistry showed that oxidation unexpectedly proceeds together with protonation of the starting compound. We proved that the nitrogen atom in the heterocycle of hydroxyquinolines is protonated during the apparent 0.7 electron oxidation process. This was rationalized by the autodeprotonation reaction by another two starting molecules of hydroxyquinoline, so that the overall oxidation mechanism involves two electrons and three starting molecules. Both the electrochemical and spectroelectrochemical results showed that the oxidation mechanism is not influenced by the presence of the carboxylic group in the chemical structure of hydroxyquinolines, as results from oxidation of 2,7-dimethyl-5-hydroxyquinoline (6). In the presence of a strong proton acceptor such as pyridine, the oxidation ECEC process involves two electrons and two protons per one molecule of the hydroxyquinoline derivative. The electron transfer efficiency of hydroxyquinolines in biosystems may be related to protonation of biocompounds containing nitrogen bases. Molecular orbital calculations support the experimental findings.

  5. Equilibrium Speciation of Select Lanthanides in the Presence of Acidic Ligands in Homo- and Heterogeneous Solutions

    SciTech Connect

    Robinson, Troy A

    2011-08-01

    This dissertation explores lanthanide speciation in liquid solution systems related to separation schemes involving the acidic ligands: bis(2-ethylhexyl) phosphoric acid (HDEHP), lactate, and 8-hydroxyquinoline. Equilibrium speciation of neodymium (Nd3+), sodium (Na+), HDEHP, water, and lactate in the TALSPEAK liquid-liquid extraction system was explored under varied Nd3+ loading of HDEHP in the organic phase and through extraction from aqueous HCl and lactate media. System speciation was probed through vapor pressure osmometry, visible and Fourier Transform Infrared (FTIR) spectroscopy, 22Na and 13C labeled lactate radiotracer distribution measurements, Karl Fischer titrations, and equilibrium pH measurements. Distribution of Nd3+, Na+, lactate, and equilibrium pH were modeled using the SXLSQI software to obtain logKNd and logKNa extraction constants under selected conditions. Results showed that high Nd3+ loading of the HDEHP led to Nd3+ speciation that departs from the ion exchange mechanism and includes formation of highly aggregated, polynuclear [NdLactate(DEHP)2]x; (with x > 1). By substituting lanthanum (La3+) for Nd3+ in this system, NMR scoping experiments using 23Na, 31P nuclei and 13C labeled lactate were performed. Results indicated that this technique is sensitive to changes in system speciation, and that further experiments are warranted. In a homogeneous system representing the TALSPEAK aqueous phase, Lactate protonation behavior at various temperatures was characterized using a combination of potentiometric titration and modeling with the Hyperquad computer program. The temperature dependent deprotonation behavior of lactate showed little change with temperature at 2.0 M NaCl ionic strength. Cloud point extraction is a non-traditional separation technique that starts with a homogeneous

  6. Clioquinol and pyrrolidine dithiocarbamate complex with copper to form proteasome inhibitors and apoptosis inducers in human breast cancer cells

    PubMed Central

    Daniel, Kenyon G; Chen, Di; Orlu, Shirley; Cui, Qiuzhi Cindy; Miller, Fred R; Dou, Q Ping

    2005-01-01

    Introduction A physiological feature of many tumor tissues and cells is the tendency to accumulate high concentrations of copper. While the precise role of copper in tumors is cryptic, copper, but not other trace metals, is required for angiogenesis. We have recently reported that organic copper-containing compounds, including 8-hydroxyquinoline-copper(II) and 5,7-dichloro-8-hydroxyquinoline-copper(II), comprise a novel class of proteasome inhibitors and tumor cell apoptosis inducers. In the current study, we investigate whether clioquinol (CQ), an analog of 8-hydroxyquinoline and an Alzheimer's disease drug, and pyrrolidine dithiocarbamate (PDTC), a known copper-binding compound and antioxidant, can interact with copper to form cancer-specific proteasome inhibitors and apoptosis inducers in human breast cancer cells. Tetrathiomolybdate (TM), a strong copper chelator currently being tested in clinical trials, is used as a comparison. Methods Breast cell lines, normal, immortalized MCF-10A, premalignant MCF10AT1K.cl2, and malignant MCF10DCIS.com and MDA-MB-231, were treated with CQ or PDTC with or without prior interaction with copper, followed by measurement of proteasome inhibition and cell death. Inhibition of the proteasome was determined by levels of the proteasomal chymotrypsin-like activity and ubiquitinated proteins in protein extracts of the treated cells. Apoptotic cell death was measured by morphological changes, Hoechst staining, and poly(ADP-ribose) polymerase cleavage. Results When in complex with copper, both CQ and PDTC, but not TM, can inhibit the proteasome chymotrypsin-like activity, block proliferation, and induce apoptotic cell death preferentially in breast cancer cells, less in premalignant breast cells, but are non-toxic to normal/non-transformed breast cells at the concentrations tested. In contrast, CQ, PDTC, TM or copper alone had no effects on any of the cells. Breast premalignant or cancer cells that contain copper at concentrations

  7. Nanomolar colorimetric quantitative detection of Fe3 + and PPi with high selectivity

    NASA Astrophysics Data System (ADS)

    Li, Zhanxian; Li, Haixia; Shi, Caixia; Yu, Mingming; Wei, Liuhe; Ni, Zhonghai

    2016-04-01

    A novel rhodamine and 8-hydroxyquinoline-based derivative was synthesized, which is shown to act as a colorimetric chemosensor for Fe3 + in aqueous solution with high selectivity over various environmentally and biologically relevant metal ions and anions with a distinct color change from colorless to pink in very fast response time (< 1 min). Fe3 + can be detected quantitatively in the concentration range from 6.7 to 16 μM and the detection limit (LOD) on UV-vis response of the sensor can be as low as 15 nM. The 'in situ' prepared Fe3 + complex (1 ṡ Fe) showed high selectivity toward PPi against many common anions, and sensitivity (the LOD can be as low as 71 nM). In addition, both the chemosensor and the 'in situ' prepared Fe3 + complex are reusable for the detection of Fe3 + and PPi respectively.

  8. Biochemical studies of phenoloxidase and utilization of catecholamines in Cryptococcus neoformans.

    PubMed Central

    Polacheck, I; Hearing, V J; Kwon-Chung, K J

    1982-01-01

    Protoplasts of Cryptococcus neoformans contain phenoloxidase as a membrane-bound enzyme. The enzyme appeared to be attached on the inner side of cytoplasmic membranes. Synthesis of the enzyme was derepressed by low levels of glucose but was not affected by the level of ammonium. Copper chelators which inhibited the phenoloxidase of other organisms did not affect cryptococcal enzymes. However, cyanide- or iron-chelating agents such as hydroximide derivates or 8-hydroxyquinoline were effective inhibitors, suggesting that cryptococcal phenoloxidase is an iron-containing enzyme. Phenoloxidase of C. neoformans catalyzed the oxidation of various diphenols via dopachrome and labile intermediates to melanin polymers. The kinetic constants (Km) of the phenoloxidase and the permease for dopamine and norepinephrine were low. The correlation between phenoloxidase and the preferential growth of C. neoformans in the host brain is discussed. PMID:6804439

  9. “Size-selectivity” in the template-directed assembly of dinuclear triple-stranded helicates

    PubMed Central

    Albrecht, Markus; Blau, Oliver; Fröhlich, Roland

    2002-01-01

    The self-assembly of supramolecular structures depends on a subtle interplay of a series of different control mechanisms. The geometric as well as electronic complementarity of the molecular building blocks is crucial for the specific formation of defined supramolecular species. In addition, secondary effects, like templating, also have an important function. The templating ability of different cations in the formation of triple-stranded helicate-type complexes from alkyl-bridged di(8-hydroxyquinoline) ligands is investigated by introduction of alkyl chains of different length as ligand spacers. Hereby a “size-selectivity” between the cations and the dinuclear helicate-type complexes {(ligand)3M2} is observed. Large cations support the formation of big dinuclear complexes, whereas small cations are able to template the formation of small complexes. PMID:11959938

  10. Biochemically designed polymers as self-organized materials

    NASA Astrophysics Data System (ADS)

    Alva, Shridhara; Sarma, Rupmoni; Marx, Kenneth A.; Kumar, Jayant; Tripathy, Sukant K.; Akkara, Joseph A.; Kaplan, David L.

    1997-02-01

    Self assembled molecular systems are a focus of attention for material scientists as they provide an inherent molecular level organization responsible for enhanced material properties. We have developed polymeric molecular systems with interesting optical properties by biochemical engineering, which can be self assembled to thin films. Horseradish peroxidase catalyzed polymerizations of phenolic monomers: 9-hydroxyquinoline-5-sulfonic acid, acid red and decyl ester (d&l isomers) of tyrosine, have been achieved in the presence of hydrogen peroxide. The polymer of 8- hydroxyquinoline-5-sulfonic acid acts as a polymeric ligand that can be used for metal ion sensing. The polymer of acid red, with azo functional groups in the polymer backbone, shows interesting optical properties. Amphiphilic derivatives of tyrosine self assemble into tubules from micelles in aqueous solutions. These tubules have been enzymatically polymerized to polymeric tubules. The tubules are of 5 micrometers average diameter and > 200 micrometers length. The formation and properties of these tubules are discussed.

  11. Fluorimetric sequential injection determination of magnesium using 8-hydroxiquinoline-5-sulfonic acid in a micellar medium.

    PubMed

    de Armas, G; Cladera, A; Becerra, E; Estela, J M; Cerdà, V

    2000-05-31

    A fluorimetric sequential injection method for the determination of magnesium is proposed. The system is based on the complex formation between Mg(II) and 8-hydroxyquinoline-5-sulfonic acid (HQS). The reaction was carried out in the presence of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) as a masking agent. Cetyltrimethylammonium chloride (HTAC) was employed as a fluorescence enhancer. The influence of several variables, such as reagent concentration, volumes and pH has been investigated. The reagent was prepared in a 0.1 M Tris-HCl buffer solution (pH 9). A detection limit of 12 mug l(-1) magnesium was obtained. The proposed method was applied to the determination of magnesium in natural waters.

  12. Polyaniline microtubes with a hexagonal cross-section and pH-sensitive fluorescence properties.

    PubMed

    Liu, Zhaoyuan; Zhu, Ying; Wang, Liang; Ding, Chunmei; Wang, Nü; Wan, Meixiang; Jiang, Lei

    2011-03-16

    Polyaniline (PANI) microtubes with a hexagonal cross-section are successfully synthesized by a self-assembly process in the presence of 8-hydroxyquinoline-5-sulfonic acid (HQS) as a dopant and FeCl(3) as an oxidant. The wall thickness of the PANI/HQS microtubes can be adjusted by the content of the oxidant. It is proposed that the aniline/HQS salts serve as a hard template for the formation of the hexagonal-cross-section microtubes. Moreover, PANI/HQS microtubes combined with ZnSO(4) show pH-dependent fluorescence. PANI hexagonal-cross-section microtubes combined with a pH-sensitive fluorescence may promise potential applications in fields such as chemical sensors and confined reaction vessels.

  13. Accurate quantification of two key time points used in the determination of hydroxyl polyaluminum species by ferron timed spectrophotometry.

    PubMed

    Zhang, Jing; Yong, Xiaojing; Zhao, Dongyan; Shi, Qiuyi

    2015-01-01

    The content of mononuclear Al (Ala%) changed with its determination time (ta) under different dosages of Ferron (7-iodo-8-hydroxyquinoline-5-sulfonic acid, [Ferron]), and the change of Ala% with [Ferron] at different ta was systematically investigated for the first time. Thus, the most appropriate ta was found with the optimal [Ferron]. Also, the judgment of the platform (flat or level portion) of the complete reaction on the absorption-time curve determined in the hydroxyl polyaluminum solution by Ferron timed spectrophotometry (Ferron assay) was first digitized. The time point (tb) of complete reaction between the medium polyaluminum (Alb) and Ferron reagent depended on the reaction extent, and time could not be used only to judge. Thus, the tb was accurately determined and reduced to half of original, which improved the experiment efficiency significantly. The Ferron assay was completely optimized.

  14. Self-assembled polymeric chelate nanoparticles as potential theranostic agents.

    PubMed

    Škodová, M; Černoch, P; Štěpánek, P; Chánová, E; Kučka, J; Kálalová, Z; Kaňková, D; Hrubý, M

    2012-12-21

    Improvements in cancer diagnostics and therapy have recently attracted the interest of many different branches of science. This study presents one of the new possible approaches in the diagnostics and therapy of cancer by using polymeric chelates as carriers. Graft copolymers with a backbone containing 8-hydroxyquinoline-5-sulfonic acid chelating groups and poly(ethylene oxide) hydrophilic grafts are synthesized and characterized. The polymers assemble and form particles after the addition of a biometal cation, such as iron or copper. The obtained nanoparticles exhibit a hydrodynamic diameter of around 25 nm and a stability of at least several hours, which are counted as essential parameters for biomedical purposes. To prove their biodegradability, a model degradation with deferoxamine is performed and, together with high radiolabeling efficiency with copper-64, their possible use for nuclear medicine purposes is demonstrated.

  15. Electrolyte-doped ice as a platform for atto- to femtoliter reactor enabling zeptomol detection.

    PubMed

    Hashimoto, Takuya; Tasaki, Yuiko; Harada, Makoto; Okada, Tetsuo

    2011-05-15

    Rapid freezing of an aqueous electrolyte in liquid nitrogen provides an effective way to fabricate uniform-sized liquid pores with the radius ranging from 0.15 to 3 μm (<1% rsd), corresponding to atto- to femtoliter volumes. The size of liquid pores depends on the temperature, and the concentration and type of a salt incorporated into an original aqueous solution. When the concentration of a salt is kept lower than 20 mM, liquid pores are discretely distributed in an ice matrix. Unlike usual small spaces accommodating liquid water, the pore size is tunable and continuously variable by changing the above experimental parameters. The liquid pore has been utilized as microreactors, in which the fluorescent complexation between Mg(2+) and 8-hydroxyquinoline-5-sulfonic acid (HQS) is studied. Under the optimum condition, fluorescence from Mg(2+) ions in the zeptomol level confined in a liquid pore is detected.

  16. Rapid and sensitive colorimetric determination of cobalt(II).

    PubMed

    Eldawy, M A; Tawfik, A S; Elshabouri, S R

    1976-05-01

    A highly selective and sensitive spectrophotometric determination of cobalt (II) was developed. 7-Nitroso-8-hydroxyquinoline-5-sulfonic acid sodium salt was used as the chromogenic reagent for color development. Although other metals form colored chelates with the ligand, it was possible to develop a selective method using McIlvaine's pH 8 citric acid-phosphate buffer. Under these conditions, iron(II), iron (III), copper (II), zinc (II), and manganese (II), minerals likely to be compounded with cobalt (II) in geriatric formulations, do not interfere with the precision of the method or the color development. Calcium (II) and magnesium (II) do not form colored chelates with the used ligand. Hormones, vitamins, and additives likely to be present along with the cobalt ion in pharmaceutical formulations do not interfere. The sensitivity is 0.37 mug of cobalt (II)/ml of sample solution.

  17. Fluorimetric determination of aluminium in water by sequential injection through column extraction.

    PubMed

    Brach-Papa, C; Coulomb, B; Branger, C; Margaillan, A; Théraulaz, F; Van Loot, P; Boudenne, J L

    2004-03-01

    A fluorimetric procedure for the determination of aluminium with matrix removal in drinking water is proposed. The system is based both on the solid phase extraction of aluminium on a new chelating resin (XAD-4 modified by grafting salicylic acid) and the fluorimetric detection of a complex formed between 8-hydroxyquinoline-5-sulfonic acid (HQS) and Al(III), after elution of the resin by hydrochloric acid. The sorption and elution of aluminium were studied in both competitive and noncompetitive conditions, varying pH, flow-rates, volume and concentration of reagents, as well as time contact. The optimised procedure allows determination of Al3+ at the sub-ppb level (LOD: 0.2 microg L(-1) for 1 ml of sample) within a working range of 0.2-500 microg L(-1). The analytical procedure was successfully employed for the determination of aluminium in drinking water during and after flocculation/coagulation treatment processes.

  18. Selectivity enhancements for the determination of thorium by flow-injection analysis through the formation of the Th-DTPA-HQS fluorescent ternary complex.

    PubMed

    Ye, L; Lucy, C A

    1996-06-01

    Addition of diethylenetriaminepentaacetic acid (DTPA) to the fluorescent binary complex of thorium and 8-hydroxyquinoline-5-sulfonic acid (HQS) forms the Th-DTPA-HQS fluorescent ternary complex. The formation of this ternary complex enhances the selectivity for the determination of thorium. Excesses of DTPA and HQS are used as reagents in flow-injection analysis to detect thorium. The excess DTPA effectively masks potentially interfering ions by preventing the formation of fluorescent binary metal-HQS complexes. The presence of lanthanides and transition metals does not interfere with the thorium detection with this method (the ratio of molar intensity for metals to molar intensity for thorium is <0.3% with the exception of lutetium, for which molar intensity ratio is 1.34%). The detection limit for thorium is 12 ng ml(-1).

  19. Polypyrrole nanowire-based enzymatic biofuel cells.

    PubMed

    Kim, Jihun; Kim, Sung In; Yoo, Kyung-Hwa

    2009-10-15

    Glucose/O(2) biofuel cells with an improved power density were developed, using polypyrrole (PPy) nanowires containing glucose oxidase and 8-hydroxyquinoline-5-sulfonic acid hydrate as an anode. The PPy nanowire anode was made by electropolymerizing within the nanopores of an anodized aluminum oxide (AAO) template, and then dissolving the AAO template. The nanowire-type biofuel cell exhibited a higher power density than the film-type biofuel cell by two orders of magnitude; this was likely due to an increase in surface area and enzyme loading. Additionally, we constructed a glucose/O(2) biofuel cell covered with a fluidic channel. Biofuel cells with and without a fluidic channel had comparable performance, demonstrating the feasibility of integrated biofuel cells within a fluidic cell.

  20. A simple and sensitive colorimetric assay of zinc in serum using cationic porphyrin.

    PubMed

    Makino, T

    1999-04-01

    A direct colorimetric method is presented for simple and sensitive determination of serum zinc in 0.05-ml samples, using a cationic porphyrin, alpha,beta,gamma,delta-tetrakis(4-N-trimethylaminophenyl) porphine tetratoluenesulfonate salt (ttmapp, epsilon = 41.5 x 10(4) l/mol per cm at 421 nm). 7-Iodo-8-hydroxyquinoline-5-sulfonic acid (Ferron) as an accelerator for the incorporation of zinc into ttmapp was most effective. Interference of iron, copper and conjugated bilirubin in serum can be eliminated in the presence of proteins such as albumin in serum. Within-run and between-run coefficients of variation (CV) were in the ranges of 0.76-3.59 and 2.08-5.20%. A good correlation was observed between this method and atomic absorption spectrometry (AAS).

  1. Bio-recognitive photonics of a DNA-guided organic semiconductor

    NASA Astrophysics Data System (ADS)

    Back, Seung Hyuk; Park, Jin Hyuk; Cui, Chunzhi; Ahn, Dong June

    2016-01-01

    Incorporation of duplex DNA with higher molecular weights has attracted attention for a new opportunity towards a better organic light-emitting diode (OLED) capability. However, biological recognition by OLED materials is yet to be addressed. In this study, specific oligomeric DNA-DNA recognition is successfully achieved by tri (8-hydroxyquinoline) aluminium (Alq3), an organic semiconductor. Alq3 rods crystallized with guidance from single-strand DNA molecules show, strikingly, a unique distribution of the DNA molecules with a shape of an `inverted' hourglass. The crystal's luminescent intensity is enhanced by 1.6-fold upon recognition of the perfect-matched target DNA sequence, but not in the case of a single-base mismatched one. The DNA-DNA recognition forming double-helix structure is identified to occur only in the rod's outer periphery. This study opens up new opportunities of Alq3, one of the most widely used OLED materials, enabling biological recognition.

  2. Investigation of energy transfer and charge trapping in dye-doped organic light-emitting diodes by magneto-electroluminescence measurement

    NASA Astrophysics Data System (ADS)

    Peng, Qiming; Gao, Na; Li, Weijun; Chen, Ping; Li, Feng; Ma, Yuguang

    2013-05-01

    We investigated the energy transfer and charge trapping (CT) in dye-doped organic light-emitting devices by using the magneto-electroluminescence as a tool. An intra-molecular charge-transfer fluorescent material N,N-diphenyl-4-(9-phenylnaphtho-[2,3-c][1,2,5]thiadiazol-4-yl)aniline was selected as the guest emitter. The tri-(8-hydroxyquinoline)-aluminum and 1,3-bis(9-carbazolyl)benzene were selected as the hosts. Our results demonstrate that as the energy difference between the HOMO (highest occupied molecular orbital)/LUMO (lowest unoccupied molecular orbital) of the host and the guest (ΔEHOMO/ΔELUMO) increases, the CT becomes more dominant, and the CT cannot be ignored even when the ΔEHOMO/ΔELUMO is small and the emission spectrum of the host overlaps the absorption spectrum of the guest well.

  3. Simulating atomic force microscope images with density functional theory: The role of nonclassical contributions to the force

    NASA Astrophysics Data System (ADS)

    Schaffhauser, Philipp; Kümmel, Stephan

    2016-07-01

    We discuss a scheme for calculating atomic force microscope images within the framework of density functional theory (DFT). As in earlier works [T. L. Chan et al., Phys. Rev. Lett. 102, 176101 (2009), 10.1103/PhysRevLett.102.176101; M. Kim and J. R. Chelikowsky, Appl. Surf. Sci. 303, 163 (2014), 10.1016/j.apsusc.2014.02.127] we do not simulate the cantilever explicitly, but consider it as a polarizable object. We go beyond previous studies by discussing the role of exchange and correlation effects; i.e., we approximately take into account the Pauli interaction between sample and cantilever. The good agreement that we find when comparing our calculated images to experimental images for the difficult case of the 8-hydroxyquinoline molecule demonstrates that exchange-correlation effects can play an important role in the DFT-based interpretation of AFM images.

  4. Recovery and Extraction of Heavy Metal Ions Using Ionic Liquid as Green Solvent

    NASA Astrophysics Data System (ADS)

    Kumano, Masami; Yabutani, Tomoki; Motonaka, Junko; Mishima, Yuji

    Ionic liquids are expected to replace conventional organic solvents in organic synthesis, solvent extraction and electrochemistry due to their unique characters such as low volatility, high stability and so on. In this work, N,N,-diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis(trifluoromethansulfonyl)imide was used as an alternative solvent to extract heavy metal ions. As the extracting conditions, the additional effect of 8-hydroxyquinoline (8-HQ) as metal chelating agent into ionic liquids, shaking time and volume ratio were investigated. As extraction efficiency depended on 8-HQ concentration significantly, in order to extract high concentrated metal ions the solubility of 8-HQ into ionic liquid was tested. N,N,-diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis(trifluoromethansulfonyl)imide had good solubility of 8-HQ. Consequently, 5 μmol of copper, zinc, cadmium and manganese could be completely recovered with 100 μl of ionic liquid.

  5. Voltage reduction in organic light-emitting diodes

    SciTech Connect

    Hung, L. S.; Mason, M. G.

    2001-06-04

    For practical applications, it is important to operate organic light-emitting devices at low voltages and low power consumption. When both the cathode and anode are perfectly injecting, low electron mobility in electron-transport materials, such as tris-(8-hydroxyquinoline)aluminum (Alq), becomes a limiting factor on voltage reduction. In this letter copper phthalocyanine (CuPc) is replaced for Alq as an electron-transport layer, and interfacial modification is utilized to enhance electron injection from the CuPc electron-transport layer into the Alq emissive layer. The outcome of this structure significantly facilitates electron transport through the organic materials, thus resulting in substantial reduction in operating voltages and power consumption. {copyright} 2001 American Institute of Physics.

  6. A sensitive spectrophotometric method for the determination of sulfonamides in pharmaceutical preparations.

    PubMed

    Nagaraja, Padmarajaiah; Naik, Shailendra D; Shrestha, Ashwinee Kumar; Shivakumar, Anantharaman

    2007-09-01

    A new, simple and sensitive spectrophotometric method for the determination of some sulfonamide drugs has been developed. The method is based on the diazotization of sulfacetamide, sulfadiazine, sulfaguanidine, sulfamerazine, sulfamethazine, sulfamethoxazole, and their coupling with 8-hydroxyquinoline in alkaline media to yield red coloured products with absorption maxima at 500 nm. Beer's law is obeyed from 0.1-7.0 microg mL-1. The limits of quantification and limits of detection were 0.11-0.18 and 0.03-0.05 microg mL-1, respectively. Intraday precision (RSD 0.1-0.5%) and accuracy (recovery 97.3--100.8%) of the developed method were evaluated. No interference was observed from common adjuvants. The method has been successfully applied to the assay of sulpha drug in pharmaceutical formulations.

  7. Significant relaxation of residual negative carrier in polar Alq3 film directly detected by high-sensitivity photoemission

    NASA Astrophysics Data System (ADS)

    Kinjo, Hiroumi; Lim, Hyunsoo; Sato, Tomoya; Noguchi, Yutaka; Nakayama, Yasuo; Ishii, Hisao

    2016-02-01

    Tris(8-hydroxyquinoline)aluminum (Alq3) has been widely applied as a good electron-injecting layer (EIL) in organic light-emitting diodes. High-sensitivity photoemission measurement revealed a clear photoemission by visible light, although its ionization energy is 5.7 eV. This unusual photoemission is ascribed to Alq3 anions captured by positive polarization charges. The observed electron detachment energy of the anion was about 1 eV larger than the electron affinity reported by inverse photoemission. This difference suggests that the injected electron in the Alq3 layer is energetically relaxed, leading to the reduction in injection barrier. This nature is one of the reasons why Alq3 worked well as the EIL.

  8. Responses of the L5178Y tk/sup +//tk/sup -/ mouse lymphoma cell forward mutation assay. II. 18 coded chemicals

    SciTech Connect

    McGregor, D.B.; Brown, A.; Cattanach, P.; Edwards, I.; McBride, D.; Caspary, W.J.

    1988-01-01

    Eighteen chemicals were tested for their mutagenic potential in the L5178Y tk/sup +///sup -/ mouse lymphoma cell forward mutation assay by the use of procedures based upon those described previously. Cultures were exposed to the chemicals for 4 hr, then cultured for 2 days before plating in soft agar with or without trifluorothymidine (TFT), 3 ..mu..g/ml. The chemicals were tested at least twice. Significant responses were obtained with benzofuran, benzyl chloride, bromodichloromethane, butylated hydroxytoluene, chlorendic acid, o-chlorobenzalmalonitrile, 1,2,3,4-diepoxybutane, dimethyl formamide, dimethyl hydrogen phosphite, furfural, glutaraldehyde, hydroquinone, 8-hydroxyquinoline, and resorcinol. Apart from bromodichloromethane, butylated hydroxytoluene and dimethyl hydrogen phosphite, rat liver S9 mix was not a requirement for the activity of any of these compounds. Chemicals not identified as mutagens were water, tert-butyl alcohol, pyridine, and witch hazel.

  9. Cloud point extraction and flame atomic absorption spectrometric determination of cadmium and nickel in drinking and wastewater samples.

    PubMed

    Naeemullah; Kazi, Tasneem G; Shah, Faheem; Afridi, Hassan I; Baig, Jameel Ahmed; Soomro, Abdul Sattar

    2013-01-01

    A simple method for the preconcentration of cadmium (Cd) and nickel (Ni) in drinking and wastewater samples was developed. Cloud point extraction has been used for the preconcentration of both metals, after formation of complexes with 8-hydroxyquinoline (8-HQ) and extraction with the surfactant octylphenoxypolyethoxyethanol (Triton X-114). Dilution of the surfactant-rich phase with acidified ethanol was performed after phase separation, and the Cd and Ni contents were measured by flame atomic absorption spectrometry. The experimental variables, such as pH, amounts of reagents (8-HQ and Triton X-114), temperature, incubation time, and sample volume, were optimized. After optimization of the complexation and extraction conditions, enhancement factors of 80 and 61, with LOD values of 0.22 and 0.52 microg/L, were obtained for Cd and Ni, respectively. The proposed method was applied satisfactorily for the determination of both elements in drinking and wastewater samples.

  10. Systematics of the 4f energies in a series of rare-earth organic complexes determined by resonant photoemission

    NASA Astrophysics Data System (ADS)

    Thompson, J.; Arima, V.; Zou, Y.; Fink, R.; Umbach, E.; Cingolani, R.; Blyth, R. I. R.

    2004-10-01

    We report a photoemission study of the systematics of the 4f electronic structure of a family of rare-earth organic compounds. Resonant photoemission has been used to determine the binding energies of the 4fN-1 ground states, relative to those of the ligand orbitals, of a number of rare-earth tris-8-hydroxyquinolines ( REQ3 ’s). Using an empirical model these results have been extrapolated to the full series (Ce-Lu) of REQ3 ’s. It is found that in all cases, with the possible exception of Ce, the energy of the 4fN-1 ground state is less than that of the highest occupied molecular orbital, and therefore individual holes on lanthanide sites will not be stable.

  11. One-step Double-layer Thermal Evaporation Method for Organic Light Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Kee, Y. Y.; Yong, T. K.; Ong, D. S.; Tou, T. Y.

    2011-03-01

    A new one-step double-layer thermal evaporation method was used to fabricate organic light emitting diodes (OLEDs) with device structure of: ITO (anode)/N,N_-diphenyl-N,N_-bis(3-methylphenyl)-1,1_-diphenyl-4,4_-diamine (TPD) /tris-(8-hydroxyquinoline)aluminum(3) (Alq3)/Al (cathode). These OLEDs were fabricated in cleanroom on the ITO-coated glass with a sheet resistivity of 20Ω/sq and an optical transmittance of 90%. The I-V and brightness characteristic showed that the new method could produce better performance achieving lower turn-on voltage (-2V), higher peak current efficiency (+29%) and higher brightness (+36%).

  12. Improvement of Efficiency and Brightness of Red Organic Light-Emitting Devices Using Double-Quantum-Well Configuration

    NASA Astrophysics Data System (ADS)

    Mi, Rui; Cheng, Gang; Zhao, Yi; Xie, Wen-Fa; Hou, Jing-Ying; Ding, Tao; Liu, Shi-Yong

    2004-03-01

    We present red double-quantum-well organic light-emitting devices (DQW-OLEDs), in which N,N-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyo-4,4'-diamine (NPB) is used as potential barriers and hole transport layer, 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-thtramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped tris (8-hydroxyquinoline) aluminium (Alq3) as potential wells and emitter, undoped Alq3 as electron transport layer, respectively. The turn-on voltage is about 4 V. The maximum brightness and electroluminescent (EL) efficiency of the DQW device can reach 5916 cd m-2 at 16 V and 2.85 cd A-1 at 7 V, respectively. In addition, the EL efficiency of the DQW device is relatively independent of the drive voltage in the range from 5 V to 16 V.

  13. Optical and morphological characteristics of organic thin films for optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Zhong, Zhiyou; Sun, Fenglou

    2007-12-01

    Organic semiconductor thin films of tri-(8-hydroxyquinoline)-aluminum (Alq), 9,10-di-(2-naphthyl)-anthracene (ADN), and N,N'bis(naphthalen-1-yl)-N,N'bis(phenyl)-benzidine (NPB) for optoelectronic devices were deposited onto glass substrates by vacuum sublimation technique. The surface morphology and roughness of the thin film were characterized by means of atomic force microscopy (AFM). Experimental results indicate that all thin films present similar granular topography but different surface roughness. In addition, the optical transmittance spectra of thin films were measured by a double beam spectrophotometer and their corresponding optical properties were investigated. The complex refractive index and the optical band gap of thin films were obtained, respectively. Meanwhile, the dispersion behavior of the refractive index was studied in terms of Wemple-DiDomenico single oscillator model, and the oscillator parameters were achieved.

  14. Fused Methoxynaphthyl Phenanthrimidazole Semiconductors as Functional Layer in High Efficient OLEDs.

    PubMed

    Jayabharathi, Jayaraman; Ramanathan, Periyasamy; Karunakaran, Chockalingam; Thanikachalam, Venugopal

    2016-01-01

    Efficient hole transport materials based on novel fused methoxynaphthyl phenanthrimidazole core structure were synthesised and characterized. Their device performances in phosphorescent organic light emitting diodes were investigated. The high thermal stability in combination with the reversible oxidation process made promising candidates as hole-transporting materials for organic light-emitting devices. Highly efficient Alq3-based organic light emitting devices have been developed using phenanthrimidazoles as functional layers between NPB [4,4-bis(N-(1-naphthyl)-N-phenylamino)biphenyl] and Alq3 [tris(8-hydroxyquinoline)aluminium] layers. Using the device of ITO/NPB/4/Alq3/LiF/Al, a maximum luminous efficiency of 5.99 cd A(-1) was obtained with a maximum brightness of 40,623 cd m(-2) and a power efficiency of 5.25 lm W(-1). PMID:26585347

  15. Bio-recognitive photonics of a DNA-guided organic semiconductor.

    PubMed

    Back, Seung Hyuk; Park, Jin Hyuk; Cui, Chunzhi; Ahn, Dong June

    2016-01-01

    Incorporation of duplex DNA with higher molecular weights has attracted attention for a new opportunity towards a better organic light-emitting diode (OLED) capability. However, biological recognition by OLED materials is yet to be addressed. In this study, specific oligomeric DNA-DNA recognition is successfully achieved by tri (8-hydroxyquinoline) aluminium (Alq3), an organic semiconductor. Alq3 rods crystallized with guidance from single-strand DNA molecules show, strikingly, a unique distribution of the DNA molecules with a shape of an 'inverted' hourglass. The crystal's luminescent intensity is enhanced by 1.6-fold upon recognition of the perfect-matched target DNA sequence, but not in the case of a single-base mismatched one. The DNA-DNA recognition forming double-helix structure is identified to occur only in the rod's outer periphery. This study opens up new opportunities of Alq3, one of the most widely used OLED materials, enabling biological recognition.

  16. Color-stable and efficient stacked white organic light-emitting devices comprising blue fluorescent and orange phosphorescent emissive units

    NASA Astrophysics Data System (ADS)

    Chen, Ping; Xue, Qin; Xie, Wenfa; Duan, Yu; Xie, Guohua; Zhao, Yi; Hou, Jingying; Liu, Shiyong; Zhang, Liying; Li, Bin

    2008-10-01

    We have demonstrated two kinds of stacked white organic light-emitting diodes (WOLEDs) employing tri(8-hydroxyquinoline) aluminum:20 wt %Mg/MoO3 as charge generation layer. White light emission can be obtained by mixing blue fluorescence and orange phosphorescence. Stacked WOLED with individual blue fluorescent and orange phosphorescent emissive units has better color stability and higher efficiency than that with double white emissive units, which is attributed to the avoidance of the movement of charges recombination zone and elimination of the Dexter energy transfer between blue and orange emission layers occurring in the latter. The efficiency of the stacked WOLED is 35.9 cd/A at 1000 cd/m2.

  17. Identification of xylem occlusions occurring in cut clematis (Clematis L., fam. Ranunculaceae Juss.) stems during their vase life.

    PubMed

    Jedrzejuk, Agata; Rochala, Julia; Zakrzewski, Jacek; Rabiza-Świder, Julita

    2012-01-01

    During the vase life of cut stems obstruction of xylem vessels occurs due to microbial growth, formation of tyloses, deposition of materials in the lumen of xylem vessels and the presence of air emboli in the vascular system. Such obstructions may restrict water uptake and its transport towards upwards thus lowering their ornamental value and longevity of cut flowers. Clematis is a very attractive plant material which may be used as cut flower in floral compositions. Nothing is known about the histochemical or cytological nature of xylem blockages occurring in cut stems of this plant. This study shows that in clematis, tyloses are the main source of occlusions, although bacteria and some amorphic substances may also appear inside the vessels. A preservative composed of 200 mg dm(-3) 8-HQC (8-hydroxyquinolin citrate) and 2% sucrose arrested bacterial development and the growth of tyloses. This information can be helpful in the development of new treatments to improve keeping qualities of cut clematis stems.

  18. Preservative solution for gamma irradiated chrysanthemum cut flowers

    NASA Astrophysics Data System (ADS)

    Kikuchi, Olivia Kimiko; Del Mastro, Nelida Lucia; Wiendl, Frederico Maximiliano

    1995-09-01

    Yellow mini-chrysanthemums were irradiated in a Cobalt-60 Gammacell at the dose of 900 Gy (467 Gy/h) one day after harvest. Samples of 50 flowers, parcially opened buds were used to estimate the flower viability. Aluminum sulfate and 8-hydroxyquinoline sulfate were used as two preservative solutions aiming to protect the cut flowers. Our results indicated that the stem immersion in the preservative solutions before and after the irradiation treatment was an efficient procedure, stimulating the flowers development and maintaining the vase-life almost as long as the controls. The present work concludes that it would be possible to use preservative solutions to minimize the damaging effects of the ionizing radiation on chysanthemum cut flowers, maintaining at the same time the disinfestation action of radiation processing.

  19. [Multiplayer white organic light-emitting diodes with different order and thickness of emission layers].

    PubMed

    Xu, Wei; Lu, Fu-Han; Cao, Jin; Zhu, Wen-Qing; Jiang, Xue-Yin; Zhang, Zhi-Lin; Xu, Shao-Hong

    2008-02-01

    In multilayer OLED devices, the order and thickness of the emission layers have great effect on their spectrum. Based on the three basic colours of red, blue and green, a series of white organic light-emitting diodes(WOLEDS)with the structure of ITO/CuPc(12 nm)/NPB(50 nm)/EML/LiF(1 nm)/Al(100 nm) and a variety of emission layer's orders and thicknesses were fabricated. The blue emission material: 2-t-butyl-9,10-di-(2-naphthyl)anthracene (TBADN) doped with p-bis(p-N, N-diphenyl-amono-styryl)benzene(DSA-Ph), the green emission material: tris-[8-hydroxyquinoline]aluminum(Alq3) doped with C545, and the red emission material: tris-[8-hydroxyquinoline]aluminum( Alq3) doped with 4-(dicyanomethylene)-2-t-butyl-6-(1, 1, 7, 7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) were used. By adjusting the order and thickness of each emission layer in the RBG structure, we got a white OLED with current efficiency of 5.60 cd x A(-1) and Commission Internationale De L'Eclairage (CIE) coordinates of (0. 34, 0.34) at 200 mA x cm(-2). Its maximum luminance reached 20 700 cd x m(-2) at current density of 400 mA x cm(-2). The results were analyzed on the basis of the theory of excitons' generation and diffusion. According to the theory, an equation was set up which relates EL spectra to the luminance efficiency, the thickness of each layer and the exciton diffusion length. In addition, in RBG structure with different thickness of red layer, the ratio of th e spectral intensity of red to that of blue was calculated. It was found that the experimental results are in agreement with the theoretical values. PMID:18479000

  20. Molecular mechanics approach for design and conformational studies of macrocyclic ligands

    SciTech Connect

    Rohini,; Akbar, Rifat; Kanungo, B. K.

    2015-08-28

    Computational Chemistry has revolutionized way of viewing molecules at the quantum mechanical scale by allowing simulating various chemical scenarios that are not possible to study in a laboratory. The remarkable applications of computational chemistry have promoted to design and test of the effectiveness of various methods for searching the conformational space of highly flexible molecules. In this context, we conducted a series of optimization and conformational searches on macrocyclic based ligands, 9N3Me5Ox, (1,4,7-tris(5-methyl-8-hydroxyquinoline)-1,4,7-triazacyclononane) and 12N3Me5Ox, (1,5,9-tris(5-methyl-8-hydroxyquinoline)-1,5,9-triazacyclododecane) and studied their selectivity and coordination behavior with some lanthanide metal ions in molecular mechanics and semiempirical methods. The methods include both systematic and random conformational searches for dihedral angles, torsion angles and Cartesian coordinates. Structural studies were carried out by using geometry optimization, coordination scans and electronic properties were evaluated. The results clearly show that chair-boat conformational isomer of 9N3Me5Ox ligand is more stable due to lower eclipsing ethane interaction and form stronger adduct complexes with lanthanide metal ion. This is because of the fact that, in a central unit of 9N3 of the ligand form six endo type bonds out of nine. The rest of bonds have trans conformation. In contrast, for the adduct of 12N3Me5Ox, two C-C bonds have on eclipsed conformation, and others have synclinal and antiperiplanar confirmations. The distortion of the two eclipsed conformations may affect the yields and the stability of the complexes.

  1. DNA Cleavage, Cytotoxic Activities, and Antimicrobial Studies of Ternary Copper(II) Complexes of Isoxazole Schiff Base and Heterocyclic Compounds

    PubMed Central

    Chityala, Vijay Kumar; Sathish Kumar, K.; Macha, Ramesh; Tigulla, Parthasarathy; Shivaraj

    2014-01-01

    Novel mixed ligand bivalent copper complexes [Cu. L. A. ClO4] and [Cu. L. A] where “L” is Schiff bases, namely 2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-bromophenol (DMIIMBP)/2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-chlorophenol (DMIIMCP), and “A” is heterocyclic compound, such as 1,10-phenanthroline (phen)/2,21-bipyridyl (bipy)/8-hydroxyquinoline (oxine)/5-chloro-8-hydroxyquinoline (5-Cl-oxine), have been synthesized. These complexes have been characterized by IR, UV-Vis, ESR, elemental analysis, magnetic moments, TG, and DTA. On the basis of spectral studies and analytical data, five-coordinated square pyramidal/four-coordinated square planar geometry is assigned to all complexes. The ligands and their ternary complexes with Cu(II) have been screened for antimicrobial activity against bacteria and fungi by paper disc method. The antimicrobial studies of Schiff bases and their metal complexes showed significant activity and further it is observed that the metal complexes showed more activity than corresponding Schiff bases. In vitro antitumor activity of Cu(II) complexes was assayed against human cervical carcinoma (HeLa) cancer cells and it was observed that few complexes exhibit good antitumor activity on HeLa cell lines. The DNA cleavage studies have also been carried out on pBR 322 and it is observed that these Cu(II) complexes are capable of cleaving supercoiled plasmid DNA in the presence of H2O2 and UV light. PMID:24895493

  2. The determination of specific forms of aluminum in natural water

    USGS Publications Warehouse

    Barnes, R.B.

    1975-01-01

    A procedure for analysis and pretreatment of natural-water samples to determine very low concentrations of Al is described which distinguishes the rapidly reacting equilibrium species from the metastable or slowly reacting macro ions and colloidal suspended material. Aluminum is complexed with 8-hydroxyquinoline (oxine), pH is adjusted to 8.3 to minimize interferences, and the aluminum oxinate is extracted with methyl isobutyl ketone (MIBK) prior to analysis by atomic absorption. To determine equilibrium species only, the contact time between sample and 8-hydroxyquinoline is minimized. The Al may be extracted at the sample site with a minimum of equipment and the MIBK extract stored for several weeks prior to atomic absorption analysis. Data obtained from analyses of 39 natural groundwater samples indicate that filtration through a 0.1-??m pore size filter is not an adequate means of removing all insoluble and metastable Al species present, and extraction of Al immediately after collection is necessary if only dissolved and readily reactive species are to be determined. An average of 63% of the Al present in natural waters that had been filtered through 0.1-??m pore size filters was in the form of monomeric ions. The total Al concentration, which includes all forms that passed through a 0.1-??m pore size filter, ranged 2-70 ??g/l. The concentration of Al in the form of monomeric ions ranged from below detection to 57 ??g/l. Most of the natural water samples used in this study were collected from thermal springs and oil wells. ?? 1975.

  3. Synthesis, characterization, thermal behaviour and single crystal X-ray analysis of two new insensitive high energy density materials [8-hydroxyquinolinium 5-(2,4,6-trinitrophenyl)barbiturate (I) and 8-hydroxyquinolinium 5-(5-chloro-2,4-dinitrophenyl)-1,3-dimethyl barbiturate (II)

    NASA Astrophysics Data System (ADS)

    Manickkam, V.; Devi, P. Poornima; Kalaivani, D.

    2014-12-01

    Barbiturates I and II have been synthesized as maroon red and red orange coloured solids by mixing the ethanolic solutions of 2-chloro-1,3,5-trinitrobenzene ( TNCB), pyrimidine-2,4,6(1 H,3 H,5 H)-trione [barbituric acid ( BA)] and 8-hydroxyquinoline and 1,3-dichloro-4,6-dinitrobenzene ( DCDNB), 1,3-dimethylpyrimidine-2,4,6(1 H,3 H,5 H)-trione(1,3-dimethylbarbituric acid) and 8-hydroxyquinoline respectively. The structures of these two barbiturates have been predicted from the spectral studies (UV-VIS, IR, 1H NMR, 13C NMR, mass) and elemental analysis. Qualitative tests have been carried out to infer the presence of nitrogen and nitro groups and also chlorine atom in barbiturate II. Slow evaporation of ethanol-dimethylsulphoxide/ethanol solutions of barbiturate I/barbiturate II at 293 K yielded good for X-Ray diffraction crystals. Single crystal X-ray diffraction studies of the crystals further confirm the putative structures of the barbiturates. The asymmetric unit of the barbiturate I comprises of 8-hydroxyquinolinium cation, 5-(2,4,6-trinitrophenyl) barbiturate anion and a molecule of dimethylsulphoxide (DMSO), which is used as a recrystallizing solvent. It crystallizes in the triclinic system with space group (centrosymmetric). Barbiturate II crystallizes in the orthorhombic system with space group P212121 (non-centrosymmetric). Barbiturates I and II are stable towards an impact sensitivity test, when a weight of 2 kg mass hammer is dropped from a height of 160 cm of the instrument. TGA/ DTA analyses at four different heating rates (5, 10, 20, and 40 K/min) imply that they undergo exothermic decomposition (˜85%) in three different stages between 273 and 873 K. Activation energies for these decomposition processes have been calculated by employing Kissinger and Ozawa plots. Impact sensitivity test and activation energies have revealed that the titled barbiturates are insensitive high energy density materials ( IHEDMS).

  4. Rational design of a minimal size sensor array for metal ion detection.

    PubMed

    Palacios, Manuel A; Wang, Zhuo; Montes, Victor A; Zyryanov, Grigory V; Anzenbacher, Pavel

    2008-08-01

    The focus of this study was to demonstrate that, in the luminescent sensors, the signal transduction may possibly be the most important part in the sensing process. Rational design of fluorescent sensor arrays for cations utilizing extended conjugated chromophores attached to 8-hydroxyquinoline is reported. All of the optical sensors utilized in the arrays comprise the same 8-hydroxyquinoline (8-HQ) receptor and various conjugated chromophores to yield a different response to various metal cations. This is because the conjugated chromophores attached to the receptor are partially quenched in their resting state, and upon the cation coordination by the 8-HQ, the resulting metalloquinolinolate complex displays a change in fluorescence. A delicate balance of conjugation, fluorescence enhancement, energy transfer, and a heavy metal quenching effect results in a fingerprint-like pattern of responses for each sensor-cation complex. Principal component analysis (PCA) and linear discriminant analysis (LDA) are used to demonstrate the contribution of individual sensors within the array, information that may be used to design sensor arrays with the smallest number of sensor elements. This approach allows discriminating between 10 cations by as few as two or even one sensor element. Examples of arrays comprising various numbers of sensor elements and their utility in qualitative identification of Ca(2+), Mg(2+), Cd(2+), Hg(2+), Co(2+), Zn(2+), Cu(2+), Ni(2+), Al(3+), and Ga(3+) ions are presented. A two-member array was found to identify 11 analytes with 100% accuracy. Also the best two of the sensors were tested alone and both were found to be able to discriminate among the samples with 99% and 96% accuracy, respectively. To illustrate the utility of this approach to a real-world application, identification of enhanced soft drinks based on their Ca(2+), Mg(2+), and Zn(2+) cation content was performed. The same approach to reducing array elements was used to construct three

  5. Distinguishing N-oxide and hydroxyl compounds: impact of heated capillary/heated ion transfer tube in inducing atmospheric pressure ionization source decompositions.

    PubMed

    Peiris, Dilrukshi M; Lam, Wing; Michael, Steven; Ramanathan, Ragu

    2004-06-01

    In the pharmaceutical industry, a higher attrition rate during the drug discovery process means a lower drug failure rate in the later stages. This translates into shorter drug development time and reduced cost for bringing a drug to market. Over the past few years, analytical strategies based on liquid chromatography/mass spectrometry (LC/MS) have gone through revolutionary changes and presently accommodate most of the needs of the pharmaceutical industry. Among these LC/MS techniques, collision induced dissociation (CID) or tandem mass spectrometry (MS/MS and MS(n)) techniques have been widely used to identify unknown compounds and characterize metabolites. MS/MS methods are generally ineffective for distinguishing isomeric compounds such as metabolites involving oxygenation of carbon or nitrogen atoms. Most recently, atmospheric pressure ionization (API) source decomposition methods have been shown to aid in the mass spectral distinction of isomeric oxygenated (N-oxide vs hydroxyl) products/metabolites. In previous studies, experiments were conducted using mass spectrometers equipped with a heated capillary interface between the mass analyzer and the ionization source. In the present study, we investigated the impact of the length of a heated capillary or heated ion transfer tube (a newer version of the heated capillary designed for accommodating orthogonal API source design) in inducing for-API source deoxygenation that allows the distinction of N-oxide from hydroxyl compounds. 8-Hydroxyquinoline (HO-Q), quinoline-N-oxide (Q-NO) and 8-hydroxyquinoline-N-oxide (HO-Q-NO) were used as model compounds on three different mass spectrometers (LCQ Deca, LCQ Advantage and TSQ Quantum). Irrespective of heated capillary or ion transfer tube length, N-oxides from this class of compounds underwent predominantly deoxygenation decomposition under atmospheric pressure chemical ionization conditions and the abundance of the diagnostic [M + H - O](+) ions increased with

  6. [Pretreatment of Aluminum-Lithium Alloy Sample and Determination of Argentum and Lithium by Spectral Analysis].

    PubMed

    Zhou, Hui; Tan, Qian; Gao, Ya-ling; Sang, Shi-hua; Chen, Wen

    2015-10-01

    Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Flame Atomic Absorption Spectrometry (FAAS) and Visible Spectrometry (VS) was applied for determination of Ag and Li in lithium-aluminium alloy standard sample and test sample, their respective advantages and disadvantages were compared, the excellent selectivity of ICP-OES was confirmed by analyses of certified standard sample. Three different sample digestion methods were compared and discussed in this study. It was found that the better accuracy would be obtained by digesting sample with chloroazotic acid while the content of Li was measured by FAAS, and it was better to digest sample with hydrochloric acid and hydrogen peroxide while determining Ag and Li by ICP-OES simultaneously and determining Ag by FAAS and VS. The interference of co-existing elements and elimination methods was detailedly discussed. Ammonium hydroxide was added to adjust the sample solution into alkalescent and Al, Ti, Zr was precipitated by forming hydroxide precipitation, Mg and Cu was formed complex precipitation with 8-hydroxyquinoline in this condition, then the interference from matrix element to determinate Ag by FAAS was eliminated. In addition, phosphate was used to precipitate Ti to eliminate its interference for determination of Li by FAAS. The same treatment of determination for Ag by FAAS was used to eliminate the interference of matrix element for determination of Ag by VS, the excess of nitrate was added into sample and heated to release Ag+ from silver chloride complex, and the color of 8-hydroxyquinoline was eliminated because of decomposed by heating. The accuracy of analysis result for standard sample was conspicuously improved which confirms the efficient of the method to eliminate interference in this study. The optimal digestion method and eliminate interference method was applied to lithium-aluminium alloy samples. The recovery of samples was from 100.39% to 103.01% by ICP-OES determination for Ag

  7. Rational design of a minimal size sensor array for metal ion detection.

    PubMed

    Palacios, Manuel A; Wang, Zhuo; Montes, Victor A; Zyryanov, Grigory V; Anzenbacher, Pavel

    2008-08-01

    The focus of this study was to demonstrate that, in the luminescent sensors, the signal transduction may possibly be the most important part in the sensing process. Rational design of fluorescent sensor arrays for cations utilizing extended conjugated chromophores attached to 8-hydroxyquinoline is reported. All of the optical sensors utilized in the arrays comprise the same 8-hydroxyquinoline (8-HQ) receptor and various conjugated chromophores to yield a different response to various metal cations. This is because the conjugated chromophores attached to the receptor are partially quenched in their resting state, and upon the cation coordination by the 8-HQ, the resulting metalloquinolinolate complex displays a change in fluorescence. A delicate balance of conjugation, fluorescence enhancement, energy transfer, and a heavy metal quenching effect results in a fingerprint-like pattern of responses for each sensor-cation complex. Principal component analysis (PCA) and linear discriminant analysis (LDA) are used to demonstrate the contribution of individual sensors within the array, information that may be used to design sensor arrays with the smallest number of sensor elements. This approach allows discriminating between 10 cations by as few as two or even one sensor element. Examples of arrays comprising various numbers of sensor elements and their utility in qualitative identification of Ca(2+), Mg(2+), Cd(2+), Hg(2+), Co(2+), Zn(2+), Cu(2+), Ni(2+), Al(3+), and Ga(3+) ions are presented. A two-member array was found to identify 11 analytes with 100% accuracy. Also the best two of the sensors were tested alone and both were found to be able to discriminate among the samples with 99% and 96% accuracy, respectively. To illustrate the utility of this approach to a real-world application, identification of enhanced soft drinks based on their Ca(2+), Mg(2+), and Zn(2+) cation content was performed. The same approach to reducing array elements was used to construct three

  8. Photonic hybrid crystals constructed from in situ host-guest nanoconfinement of a light-emitting complex in metal-organic framework pores

    NASA Astrophysics Data System (ADS)

    Chaudhari, Abhijeet K.; Ryder, Matthew R.; Tan, Jin-Chong

    2016-03-01

    We report the concept underpinning the facile nanoconfinement of a bulky luminous guest molecule in the pores of a metal-organic framework (MOF) host, which yields a hybrid host ⊃ guest nanomaterial with tunable opto-electronic characteristics and enhanced photostability. Utilizing an in situ host-guest confinement strategy enabled by molecular self-assembly, we show that the highly emitting ZnQ [Zn-(bis-8-hydroxyquinoline)] guest complexes could be rapidly encapsulated within the sodalite nanocages of zeolitic imidazolate framework (ZIF-8) host crystals. The nature of optical and electronic transitions phenomena of the guest-encapsulated ZIF-8 ⊃ ZnQ has been elucidated by means of fluorescence and absorption spectroscopy measurements, and substantiated further via theoretical molecular orbital calculations revealing the plausible host-guest charge transfer mechanism involved. Evidence suggests that its photophysical properties are not only strongly determined by the host-guest co-operative bonding interactions within the environment of the confined MOF nanocage, but also can be engineered to manipulate its emission color chromaticity or to shield light-sensitive emitting guests against rapid photochemical degradation.We report the concept underpinning the facile nanoconfinement of a bulky luminous guest molecule in the pores of a metal-organic framework (MOF) host, which yields a hybrid host ⊃ guest nanomaterial with tunable opto-electronic characteristics and enhanced photostability. Utilizing an in situ host-guest confinement strategy enabled by molecular self-assembly, we show that the highly emitting ZnQ [Zn-(bis-8-hydroxyquinoline)] guest complexes could be rapidly encapsulated within the sodalite nanocages of zeolitic imidazolate framework (ZIF-8) host crystals. The nature of optical and electronic transitions phenomena of the guest-encapsulated ZIF-8 ⊃ ZnQ has been elucidated by means of fluorescence and absorption spectroscopy measurements, and

  9. Fused quartz substrates for microchip electrophoresis

    SciTech Connect

    Jacobson, S.C.; Moore, A.W.; Ramsey, J.M.

    1995-07-01

    A fused quartz microchip is fabricated to perform capillary electrophoresis of metal ions complexed with 8-hydroxyquinoline-5-sulfonic acid (HQS). The channel manifold on the quartz substrate is fabricated using standard photolithographic, etching, and deposition techniques. By incorporating a direct bonding technique during the fabrication of the microchip, the substrate and cover plate can be fused together below the melting temperature for fused quartz. To enhance the resolution for the separation, the electroosmotic flow is minimized by covalently bonding polyacrylamide to the channel walls. A separation length of 16.5 mm and separation field strength of 870 V/cm enable separations to be performed in {<=}15 s. By increasing the concentration of HQS from 5 mM to 20 mM, the separation efficiency improves by approximately 3 times. The low background signal from the fused quartz substrate results in mass detection limits of 85, 61, and 134 amol and concentration detection limits of 46, 57, and 30 ppb for Zn, Cd, and Al, respectively. 30 refs., 6 figs., 2 tabs.

  10. Mercury speciation analysis in sea water by solid phase microextraction?gas chromatography?inductively coupled plasma mass spectrometry using ethyl and propyl derivatization. Matrix effects evaluation

    NASA Astrophysics Data System (ADS)

    Bravo-Sánchez, Luis R.; Ruiz Encinar, Jorge; Fidalgo Martínez, José I.; Sanz-Medel, Alfredo

    2004-01-01

    An approach to the speciation analysis of mercury in sea-water samples at sub-ppt levels by means of the hyphenation of solid phase microextraction to gas chromatography-inductively coupled plasma mass spectrometry was developed. Blank values turned out to be the limiting factor for lower detection limits of inorganic mercury. Thus, all the reagents were thoroughly cleaned using laboratory made microcolumns packed with 8-hydroxyquinoline on TSK gel. Sodium tetrapropylborate (NaBPr 4) synthesized for the purpose of derivatization of the mercury species resulted in better analytical performances of the method, probably due to lower mercury contamination, than commercial sodium tetraethylborate (NaBEt 4). Detection limits down to a few picogram per liter for both mercury and methylmercury were obtained using NaBPr 4. The high salt content of sea-water samples was responsible for strong matrix effects, which were overcome by using standards additions to the samples. The validation of the methodology was carried out by direct comparison of the results for inorganic mercury with those obtained using a flow injection system followed by preconcentration/trapping of the species and its detection by atomic absorption spectrometry. The proposed method was applied to the determination of mercury and methylmercury in coastal sea-water samples from Gijón (Asturias, Spain) and results obtained are discussed in the light of the butyltin levels previously determined in the same area.

  11. Synthesis and characterization of mixed-ligand complexes using a precursor mononuclear oxidovanadium(V) complex derived from a tridentate salicylhydrazone oxime ligand

    NASA Astrophysics Data System (ADS)

    Sutradhar, Manas; Roy Barman, Tannistha; Ghosh, Saktiprosad; Drew, Michael G. B.

    2013-04-01

    The mononuclear oxidovanadium(V) complex [VO(L)(OEt)(EtOH)] (1), where H2L = Salicyloyl hydrazone of diacetyl monooxime, reacts separately with five different reactants viz. pyridine (py), 4-methylpyridine (4mepy), 4,4'bipyridine (4,4'bipy), 8-hydroxyquinoline (Hox) and KOH to yield the mononuclear oxidovanadium complexes [VO(L)(OEt)(py)] (2), and [VO(L)(OEt)(4mepy)] (3), the binuclear complex [VO(L)(OEt)]2(μ-4,4'bipy) (4), the mononuclear bis chelate complex [VO(L)(ox)] (5) and the water soluble dioxidovanadium salt K[VO2L]·H2O (6) respectively. Complex 5 has been characterized by X-ray crystallography, and crystallizes in the orthorhombic space group Pna21 having a distorted octahedral O4N2 coordination environment. All five complexes are characterized by elemental analysis, various spectroscopic techniques (UV-Vis, IR, NMR and ESI Mass) and cyclic voltammetry. The spectral and electrochemical data of these five complexes are compared with those of the precursor complex.

  12. Preconcentration of trace uranium from seawater with solid phase extraction followed by differential pulse polarographic determination in chloroform eluate.

    PubMed

    Dojozan, D; Pournaghi-Azar, M H; Toutounchi-Asr, J

    1998-05-01

    In the present study, an effective method is presented for the separation and preconcentration of uranium (VI) by solid phase extraction (SPE). For this purpose, U(VI) oxinate is formed by the reaction of U(VI) with 8-hydroxyquinoline and adsorbed onto the octylsilane (C-8) SPE cartridge. The analyte is completely eluted with chloroform and determined by differential pulse polarography. The SPE conditions were optimized by evaluating the effective factors such as pH, oxine concentration, type and concentration of buffer and masking agent. By the proposed method a preconcentration factor more than 100 was achieved. The average recovery of uranium (VI) oxinate (0.1 mg l(-1)) was 99.8%. The relative standard deviation was 1.6% for seven replicate determinations of uranyl ion in the solution with a concentration 20 mug l(-1). Some concomitant ions such as Ca(+2), Mg(+2) and Fe(+3) which interfere in extraction or determination process of uranium were masked with EDTA in aqueous phase during the extraction process. The proposed method was successfully used for the determination of uranium in Caspian Sea and Persian Gulf water samples. PMID:18967134

  13. Synthesis, properties and thermal studies of oxorhenium(V) complexes with 3-hydrazino-5,6-diphenyl-1,2,4-triazine, benzimidazolethione and 2-hydrazinobenzimidazole. Mixed ligand complexes, pyrolytical products and biological activity

    NASA Astrophysics Data System (ADS)

    Mashaly, M. M.; El-Shafiy, H. F.; El-Maraghy, S. B.; Habib, H. A.

    2005-06-01

    A series of biologically active complexes of oxorhenium(V), were prepared by using the organic ligands 3-hydrazino-5,6-diphenyl-1,2,4-triazine (HL 1), benzimidazolethione (H 2L 2) and 2-hydrazinobenzimidazole (H 2L 3). The mixed ligand complexes of oxorhenium(V) with the previous ligands and one of the following ligands: NH 4SCN, 1,10-phenanthroline (1,10-phen), 8-hydroxyquinoline (8-OHquin) or glycine (Gly), were isolated. All the binary and mixed ligand complexes have monomeric structures and exist in the octahedral configuration. Thermal studies on these complexes showed the possibility of structural transformation from mononuclear into binuclear ones. The structures of all complexes and the corresponding thermal products were elucidated by elemental analyses, IR, electronic absorption and 1H NMR spectra, magnetic moments, conductance and TG-DSC measurements. The antifungal activities of the metal complexes towards Alternaria alternata and Aspergilus niger were tested and showed comparable behaviour with some well known antibiotics.

  14. ATOX1 gene silencing increases susceptibility to anticancer therapy based on copper ionophores or chelating drugs.

    PubMed

    Barresi, Vincenza; Spampinato, Giorgia; Musso, Nicolò; Trovato Salinaro, Angela; Rizzarelli, Enrico; Condorelli, Daniele Filippo

    2016-03-01

    Copper is a catalytic cofactor required for the normal function of many enzymes involved in fundamental biological processes but highly cytotoxic when in excess. Therefore its homeostasis and distribution is strictly regulated by a network of transporters and intracellular chaperones. ATOX1 (antioxidant protein 1) is a copper chaperone that plays a role in copper homeostasis by binding and transporting cytosolic copper to ATPase proteins in the trans-Golgi network. In the present study the Caco-2 cell line, a colon carcinoma cell line, was used as an in vitro model to evaluate if ATOX1 deficiency could affect sensitivity to experimentally induced copper dyshomeostasis. Silencing of ATOX1 increased toxicity of a short treatment with a high concentration of Cu(2+). Copper ionophores, such as 5-chloro-8-hydroxyquinoline, induced a copper-dependent cell toxicity which was significantly potentiated after ATOX1 silencing. The copper chelator TPEN (N,N,N',N'-tetrakis (2-pyridylmethyl) ethylenediamine) produced a form of cell toxicity that was reversed by the addition of Cu(2+). ATOX1 silencing increased Caco-2 cell sensitivity to TPEN toxicity. Our results suggest the possibility of a therapy with copper-chelating or ionophore drugs in subtypes of tumors showing specific alterations in ATOX1 expression. PMID:26784148

  15. Structural and spectroscopic characterizations of tetra-nuclear niobium(V) complexes of quinolinol derivatives.

    PubMed

    Amini, Mostafa M; Fazaeli, Yousef; Mohammadnezhad, Gholamhossein; Khavasi, Hamid Reza

    2015-06-01

    Reactions between niobium ethoxide and 8-hydroxy-2-methylquinoline or 5-chloro-8-hydroxyquinoline have been explored. Two new tetranuclear heteroleptic niobium complexes containing oxo, ethoxo, and quinolinate chelate rings have been synthesized and characterized by (1)H, (13)C and (93)Nb NMR, UV-Vis, and FT-IR spectroscopies, and single-crystal X-ray diffraction. The molecular structures of the niobium complexes, [Nb4(μ-O)4(μ-OEt)2(ONC10H8)2(OEt)8] (I) and [Nb4(μ-O)4(μ-OEt)2(ONC9H5Cl)2(OEt)8] (II), are composed of a pair of edge-sharing bioctahedral moieties in which connected via two almost linear oxo-bridges, with a large difference in the NbO distances. Single-crystal structures showed both complexes are centrosymmetric and contain two distinct Nb centers, and results confirmed by observation of two niobium signals in the (93)Nb NMR spectra of complexes.

  16. Newer mixed ligand Schiff base complexes from aquo-N-(2‧-hydroxy acetophenone) glycinatocopper(II) as synthon: DFT, antimicrobial activity and molecular docking study

    NASA Astrophysics Data System (ADS)

    Pramanik, Harun A. R.; Das, Dharitri; Paul, Pradip C.; Mondal, Paritosh; Bhattacharjee, Chira R.

    2014-02-01

    Synthesis of a series of newer mixed ligand copper(II) complexes of aminoacid Schiff base of the type [CuL(X)] (L = N-(2‧-hydroxy acetophenone) glycinate, X = imidazole (im) 2, benzimidazole (benz) 3, pyridine (py) 4, hydrazine (hz) 5,8-hydroxyquinoline (8-hq) 6, pyrrolidine (pyrr) 7, piperidine (pip) 8, and nicotinamide (nic) 9) have been accomplished from the interaction of an aquated Schiff base complex, [CuL(H2O)]·H2O, 1 with some selected neutral nitrogen-donor ligands. The copper(II) Schiff base complex, [CuL(H2O)]·H2O, L = N-(2‧-hydroxy acetophenone) glycinate was synthesized from the reaction of glycine and 2‧ hydroxy acetophenone and copper(II) acetate. The compounds were characterised by elemental analysis, spectral, magnetic and thermal studies. The density functional theory calculations were performed using LANL2DZ and 6-311 G(d, p) basis sets with B3LYP correlation functional to ascertain the stable electronic structure, HOMO-LUMO energy gap, chemical hardness and dipole moment of the mixed ligand complexes. A distorted square planar geometry has been conjectured for the complexes. Antibacterial activities of the ligand and its metal complexes have been tested against selected gram-positive and gram-negative strains and correlated with computational docking scores.

  17. Microemulsion extraction separation and determination of aluminium species by spectrofluorimetry.

    PubMed

    Lu, Jusheng; Tian, Jiuying; Guo, Na; Wang, Yan; Pan, Yichun

    2011-01-30

    A simple and sensitive microemulsion extraction separation method was developed for the speciation of aluminium in tea samples by spectrofluorimetry. With 8-hydroxyquinoline (8-HQ) as the chelating agent and Triton X-100 Winsor II microemulsion as the extractant, separation of aluminium species in different pH solutions was achieved by microemulsion extraction. The formation of microemulsion, the conditions of extraction and determination of aluminium species were studied. The results showed that, the contents of aluminium species in tea leaves and infusions samples, such as total aluminium, total soluble aluminium, total granular aluminium, inorganic aluminium except Al-F, and (Al-F+Al-org), were obtained successfully under the optimal conditions. The limit of detection was 0.23 μg L(-1) in pH 9.5 solution, and 0.59 μg L(-1) in pH 6.0 solution respectively; the precision (RSD) for 11 replicate measurements of 10 μg L(-1) aluminium was 2.1% in pH 9.5 solution, and 2.8% in pH 6.0 solution respectively; the recoveries for the spiked samples were 96.8-103.5%. The proposed method is simple and efficient, which has been applied to the speciation of aluminium in tea samples with satisfactory results.

  18. A high-content screening assay in transgenic zebrafish identifies two novel activators of fgf signaling.

    PubMed

    Saydmohammed, Manush; Vollmer, Laura L; Onuoha, Ezenwa Obi; Vogt, Andreas; Tsang, Michael

    2011-09-01

    Zebrafish have become an invaluable vertebrate animal model to interrogate small molecule libraries for modulators of complex biological pathways and phenotypes. We have recently described the implementation of a quantitative, high-content imaging assay in multi-well plates to analyze the effects of small molecules on Fibroblast Growth Factor (FGF) signaling in vivo. Here we have evaluated the capability of the assay to identify compounds that hyperactivate FGF signaling from a test cassette of agents with known biological activities. Using a transgenic zebrafish reporter line for FGF activity, we screened 1040 compounds from an annotated library of known bioactive agents, including FDA-approved drugs. The assay identified two molecules, 8-hydroxyquinoline sulfate and pyrithione zinc, that enhanced FGF signaling in specific areas of the brain. Subsequent studies revealed that both compounds specifically expanded FGF target gene expression. Furthermore, treatment of early stage embryos with either compound resulted in dorsalized phenotypes characteristic of hyperactivation of FGF signaling in early development. Documented activities for both agents included activation of extracellular signal-related kinase (ERK), consistent with FGF hyperactivation. To conclude, we demonstrate the power of automated quantitative high-content imaging to identify small molecule modulators of FGF. PMID:21932436

  19. Solvothermal synthesis of luminescent bis-(8 hydroxy quinoline) cadmium complex nanostructures

    NASA Astrophysics Data System (ADS)

    Khan, M. A.; Ahmed, Shafique; A, Majid; Arif Khan, Ayaz; Mahboobullah; Hashmi, Asghar; Iqbal, Tariq; Ahmed, Azhar; Ahmed, Nasar

    2014-06-01

    A facile solution- based route for the synthesis of Bis- (8- hydroxyquinoline) Cadmium (CdCh) complex nanorods, nanoflowers (bundles of nanorods) and nanosheets in an oleic acid- sodium oleate- ethanol- H2O system at 50°C -100°C was reported. Scanning Electron Microscope (SEM) images indicated that longer time and higher temperature would result in nanoflowers, while lower temperature and shorter reaction time would be suitable for the formation of nanorods. However, a novel change in these structures was observed when the concentration of the surfactant (oleic acid) was reduced and we obtained 2- D nanosheets. Fourier- transform infrared (FTIR) spectroscopy was utilized to confirm that the samples were made up of CdQ2. UV/ VIS spectroscopy was used to determine the different electronic transitions in CdQ2 molecule. All the samples possessed excellent photoluminescence (PL) properties. Photoluminescence (PL) spectra showed a prominent peak around 500 nm which indicated a strong PL emission in the green region. This methodology could be extended for the controlled, large- scale preparation of other functional complexes, and the obtained nanostructures could be introduced as the basic building blocks for novel optoelectronic devices.

  20. Clioquinol Synergistically Augments Rescue by Zinc Supplementation in a Mouse Model of Acrodermatitis Enteropathica

    PubMed Central

    Geiser, Jim; De Lisle, Robert C.; Finkelstein, David; Adlard, Paul A.; Bush, Ashley I.; Andrews, Glen K.

    2013-01-01

    Background Zinc deficiency due to poor nutrition or genetic mutations in zinc transporters is a global health problem and approaches to providing effective dietary zinc supplementation while avoiding potential toxic side effects are needed. Methods/Principal Findings Conditional knockout of the intestinal zinc transporter Zip4 (Slc39a4) in mice creates a model of the lethal human genetic disease acrodermatitis enteropathica (AE). This knockout leads to acute zinc deficiency resulting in rapid weight loss, disrupted intestine integrity and eventually lethality, and therefore provides a model system in which to examine novel approaches to zinc supplementation. We examined the efficacy of dietary clioquinol (CQ), a well characterized zinc chelator/ionophore, in rescuing the Zip4intest KO phenotype. By 8 days after initiation of the knockout neither dietary CQ nor zinc supplementation in the drinking water was found to be effective at improving this phenotype. In contrast, dietary CQ in conjunction with zinc supplementation was highly effective. Dietary CQ with zinc supplementation rapidly restored intestine stem cell division and differentiation of secretory and the absorptive cells. These changes were accompanied by rapid growth and dramatically increased longevity in the majority of mice, as well as the apparent restoration of the homeostasis of several essential metals in the liver. Conclusions These studies suggest that oral CQ (or other 8-hydroxyquinolines) coupled with zinc supplementation could provide a facile approach toward treating zinc deficiency in humans by stimulating stem cell proliferation and differentiation of intestinal epithelial cells. PMID:24015258

  1. Complexation study of NpO{sub 2}{sup +} and UO{sub 2}{sup 2+} ions with several organic ligands in aqueous solutions of high ionic strength

    SciTech Connect

    Borkowski, M.; Lis, S.; Choppin, G.R.

    1995-09-01

    The acid dissociation constants, pK{sub a}, and the stability constants for NpO{sub 2}{sup +} and UO{sub 2}{sup 2+} have been measured for certain organic ligands [acetate, {alpha}-hydroxyisobutyrate, lactate, ascorbate, oxalate, citrate, EDTA, 8-hydroxyquinoline, 1, 10-phenanthroline, and thenoyltrifluoroacetone] in 5 m (NaCl) ionic strength solution. The pK{sub a} values were determined by potentiometry or spectrometry. These methods, as well as solvent extraction with {sup 233}U and {sup 237}Np radiotracers, were used to measure the stability constants of the 1:1 and 1:2 complexes of dioxo cations. These constants were used to estimate the concentrations required to result in 10 % competition with hydrolysis in the 5 m NaCl solution. Such estimates are of value in assessing the solubility from radioactive waste of AnO{sub 2}{sup +} and AnO{sub 2}{sup 2+} in brine solutions in contact with nuclear waste in a salt-bed repository.

  2. Fluorescent pseudomonad pyoverdines bind and oxidize ferrous ion.

    PubMed

    Xiao, R; Kisaalita, W S

    1998-04-01

    Major pyoverdines from Pseudomonas fluorescens 2-79 (Pf-B), P. aeruginosa ATCC 15692 (Pa-C), and P. putida ATCC 12633 (Pp-C) were examined by absorption and fluorescence spectroscopic techniques to investigate the interaction between ferrous ion and the pyoverdine ligand. At physiological pH, ferrous ion quenched the fluorescence of all three pyoverdines much faster than ferric ion did. Also, increased absorbance at 460 nm was observed to be much faster for Fe2+ -pyoverdine than for Fe3+ -pyoverdine. At pH 7.4, about 90% of Fe3+ was bound by pyoverdine Pa-C after 24 h whereas Fe2+ was bound by the pyoverdine completely in only 5 min. The possibility that Fe2+ underwent rapid autoxidation before being bound by pyoverdine was considered unlikely, since the Fe2+ concentration in pyoverdine-free samples remained constant over a 3-min period at pH 7.4. Incubating excess Fe2+ with pyoverdine in the presence of 8-hydroxyquinoline, an Fe3+ -specific chelating agent, resulted in the formation of a Fe3+ -hydroxyquinoline complex, suggesting that the iron in the Fe2+ -pyoverdine complex existed in the oxidized form. These results strongly suggested that pyoverdines bind and oxidize the ferrous ion. PMID:9575133

  3. Tuning open-circuit voltage in organic solar cells by magnesium modified Alq3

    PubMed Central

    Chou, Chi-Ta; Lin, Chien-Hung; Wu, Meng-Hsiu; Cheng, Tzu-Wei; Lee, Jiun-Haw; Liu, Chin-Hsin J.; Tai, Yian; Chattopadhyay, Surojit; Wang, Juen-Kai; Chen, Kuei-Hsien; Chen, Li-Chyong

    2011-01-01

    The low molecular weight tris-(8-hydroxyquinoline) aluminum (Alq3) has been incorporated with magnesium (Mg) that altered the nature of its opto-electronic characteristics. The lowering of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) in Mg:Alq3, compared to pure Alq3, creates a stronger field (exceeding the exciton binding energy) at the donor-acceptor junction to dissociate the photo-generated exciton and also provides a low barrier for electron transport across the device. In an electron-only device (described in the text), a current enhancement in excess of 103, with respect to pure Alq3, could be observed at 10 V applied bias. Optimized Mg:Alq3 layer, when introduced in the photovoltaic device, improves the power conversion efficiencies significantly to 0.15% compared to the pure Alq3 device. The improvement in the photovoltaic performance has been attributed to the superior exciton dissociation and carrier transport. PMID:22087050

  4. Simulation of mixed-host emitting layer based organic light emitting diodes

    SciTech Connect

    Riku, C.; Kee, Y. Y.; Ong, T. S.; Tou, T. Y.; Yap, S. S.

    2015-04-24

    ‘SimOLED’ simulator is used in this work to investigate the efficiency of the mixed-host organic light emitting devices (MH-OLEDs). Tris-(8-hydroxyquinoline) aluminum(3) (Alq{sub 3}) and N,N-diphenyl-N,N-Bis(3-methylphenyl)-1,1-diphenyl-4,4-diamine (TPD) are used as the electron transport layer (ETL) material and hole transport layer (HTL) material respectively, and the indium-doped tin oxide (ITO) and aluminum (Al) as anode and cathode. Three MH-OLEDs, A, B and C with the same structure of ITO / HTM (15 nm) / Mixed host (70 nm) / ETM (10 nm) /Al, are stimulated with ratios TPD:Alq{sub 3} of 3:5, 5:5, and 5:3 respectively. The Poole-Frenkel model for electron and hole mobilities is employed to compute the current density-applied voltage-luminance characteristics, distribution of the electric field, carrier concentrations and recombination rate.

  5. Microenviromental investigation of polymer-bound fluorescent chelator by fluorescence microscopy and optical spectroscopy.

    PubMed

    Wang, Y; Astilean, S; Haran, G; Warshawsky, A

    2001-09-01

    8-Hydroxyquinoline-5-sulfonic acid (HQS) was immobilized onto a strong-base anion-exchange resin AG MP-1 for the purpose of microenvironment investigation, resin characterization, and possibly sensing cadmium. The maximum loading of HQS was found to be 0.9340 mmol/g of AG MP-1. A plateau for Cd complex capacity was already obtained for 0.5500 mmol of HQS/g of AG MP-1. A minicolumn experiment showed an influence of influent Cd concentration on column capacity. IR and Raman spectra proved an electrostatic mode for HQS immobilization and Cd complex formation. UV spectroscopy showed significant differences between solution and solid state for both HQS and Cd complex. A fluorescence microscopy technique was used for fluorescence spectral measurement, microdistribution imaging, and study of photobleaching of HQS and the HQS-Cd complex in the resin phase. The fluorescence of immobilized HQS was found to be red-shifted with regard to the solid-state HQS. The microdistribution of uncomplexed and Cd-complexed AG MP-1-HQS was directly visualized by fluorescence imaging, showing a nonuniform distribution. Cadmium complexation modifies the fluorescence emission of uncomplexed AG MP-1-HQS, exhibiting an increased and red-shifted emission. Significant photobleaching of the fluorescence from the Cd complex was recorded, indicating the occurrence of photochemical reactions within the microenvironment of the resin phase.

  6. Indirect determination of trace amounts of fluoride in natural waters by ion chromatography: a comparison of on-line post-column fluorimetry and ICP-MS detectors.

    PubMed

    Bayón, M M; Rodríguez Garcia, A; García Alonso, J I; Sanz-Medel, A

    1999-01-01

    An alternative method for the determination of trace levels of fluoride in drinking and sea-water samples is presented. It is based on the formation of the aluminium monofluoride complex in excess of Al3+ and separation of the two species formed (AlF2+ and Al3+) in a small (5 cm long, CG2) ion exchange guard column. The final determination is accomplished by both ICP-MS specific detection and post column derivatisation with fluorimetric detection. Fundamental studies on the formation kinetics of the complex, ion chromatographic separation and optimum aluminium concentration were carried out using spectrofluorimetric detection by post-column reaction of the species with 8-hydroxyquinoline-5-sulfonic acid in a micellar medium of cetyltrimethylammonium bromide. Fluorimetric detection showed good detection limits, but interferences from cations such as Mg2+ and Zn2+ required the use of the longer CS2 ion exchange column. Iron interfered in relatively large amounts but adding EDTA to the sample solution eliminated the interference. A similar separation methodology was applied using ICP-MS detection for the indirect determination of fluoride, by monitoring aluminium at mass 27. In this case, a detection limit of 0.1 ng ml-1 was obtained using 0.45 M HNO3 as eluent and no interference caused by high concentrations of iron was observed. The proposed method was applied to the determination of very low levels of fluoride in natural waters.

  7. Effects of anionic surfactants on ligand-promoted dissolution of iron and aluminum hydroxides.

    PubMed

    Carrasco, Naraya; Kretzschmar, Ruben; Pesch, Marie-Laure; Kraemer, Stephan M

    2008-05-15

    We investigated the influence of the surfactants sodium dodecyl sulfate (SDS) and rhamnolipid (RhL) on ligand-promoted dissolution of goethite (alpha-FeOOH) and boehmite (gamma-AlOOH) at pH 6. The siderophore desferrioxamine B (DFOB), its derivate desferrioxamine D (DFOD), ethylenediaminetetraacetic acid (EDTA), and 8-hydroxyquinoline-5-sulfonic acid (HQS) were used as ligands. The rates of ligand-promoted dissolution of goethite were significantly increased in the presence of low concentrations of anionic surfactants (<80 microM SDS; <6 mg/L RhL). At higher surfactant concentrations, however, the effects of surfactants were negligible. The dissolution rates in the presence of surfactants were not correlated with adsorbed amounts of ligands. Three possible factors contributing to these observations were further investigated and discussed: (i) adsorbed surfactants may influence ligand adsorption by changes in the ligand's surface speciation, (ii) re-adsorption of Fe-DFOB or Fe-DFOD complexes may lead to an underestimation of siderophore-promoted dissolution rates at high surfactant concentrations, and (iii) co-adsorption of protons to goethite with SDS may influence the dissolution rates. However, our results show that none of these three factors can satisfactorily explain the observed effects of anionic surfactants on ligand-promoted dissolution rates of iron and aluminum hydroxides.

  8. Development of a rapid and sensitive method for the determination of aluminum by reverse-phase high-performance liquid chromatography using a fluorescence detector.

    PubMed

    Heena; Kumar, Rajesh; Rani, Susheela; Malik, Ashok Kumar

    2015-01-01

    This study represents a new analytical high-performance liquid chromatography-fluorescence detector method for the determination of Al(III) as Al(III) complex with 8-hydroxyquinoline-5-sulfonic acid in a tap water sample and a coke sample. A micellar liquid chromatographic method is proposed for the determination of aluminum metal in the presence of cetyltrimethylammonium bromide, a cationic surfactant (0.05 M) used for the solubilization of the aluminum complex. The influence of pH and ligand concentration on the formation of the complex was studied by adding a small amount of 0.1 M sodium hydroxide. The metal chelate was detected at λEx 410 nm and λEm 510 nm. This method eliminates the need for addition of reagent or organic modifier to the mobile phase. The complex was analyzed using an Ascentis Express C18 column and a mobile phase consisting of acetonitrile, methanol and water (55 : 30 : 15). Under the optimized conditions, the linear range was 1-200 µg L(-1) and the limit of detection was 0.05 µg L(-1). The method showed a good detector response over the range of interest and was successfully applied for the determination of trace Al(III) in canned coke and water samples containing excess of Mg(II), Ca(II) and other matrices.

  9. Characterization of the zinc binding site of bacterial phosphotriesterase.

    PubMed

    Omburo, G A; Kuo, J M; Mullins, L S; Raushel, F M

    1992-07-01

    The bacterial phosphotriesterase has been found to require a divalent cation for enzymatic activity. This enzyme catalyzes the detoxification of organophosphorus insecticides and nerve agents. In an Escherichia coli expression system significantly higher concentrations of active enzyme could be produced when 1.0 mM concentrations of Mn2+, Co2+, Ni2+, and Cd2+ were included in the growth medium. The isolated enzymes contained up to 2 equivalents of these metal ions as determined by atomic absorption spectroscopy. The catalytic activity of the various metal enzyme derivatives was lost upon incubation with EDTA, 1,10-phenanthroline, and 8-hydroxyquinoline-5-sulfonic acid. Protection against inactivation by metal chelation was afforded by the binding of competitive inhibitors, suggesting that at least one metal is at or near the active site. Apoenzyme was prepared by incubation of the phosphotriesterase with beta-mercaptoethanol and EDTA for 2 days. Full recovery of enzymatic activity could be obtained by incubation of the apoenzyme with 2 equivalents of Zn2+, Co2+, Ni2+, Cd2+, or Mn2+. The 113Cd NMR spectrum of enzyme containing 2 equivalents of 113Cd2+ showed two resonances at 120 and 215 ppm downfield from Cd(ClO4)2. The NMR data are consistent with nitrogen (histidine) and oxygen ligands to the metal centers.

  10. Determination of conditional stability constants of cadmium-humic acid complexes in freshwater by use of a competitive ligand equilibration-solvent extraction technique

    SciTech Connect

    Van Ginneken, L.; Blust, R.

    2000-02-01

    A technique for determining organic complexation of cadmium in freshwater using competitive ligand equilibration coupled with solvent extraction was evaluated. The method involves a competitive equilibration of the sample with potassium iodide and pyridine followed by extraction of the mixed cadmium-iodide-pyridine complex into a benzene phase. The final distribution of the metal is measured by gamma ray spectrometry. The method's suitability was verified by performing extractions on the model ligand 8-hydroxyquinoline-5-sulfonic acid (sulfoxine), which forms well-characterized complexes with cadmium. The speciation results so obtained were in excellent agreement with results calculated with a chemical speciation model. The method was applied to study complexation of cadmium with two commercially available humic acids in reconstituted freshwater at relatively high cadmium concentrations to mimic polluted freshwaters. The obtained titration data were fitted to a one-site Langmuir adsorption model, yielding values of 10{sup 6.59} and 10{sup 6.52} for the respective conditional stability constants, and 0.57 and 0.90 {micro}M for the respective ligand concentrations.

  11. Mechanism of porphobilinogen synthase. Requirement of Zn2+ for enzyme activity.

    PubMed

    Bevan, D R; Bodlaender, P; Shemin, D

    1980-03-10

    The role of metal ions in the mechanism of action of bovine liver porphobilinogen synthase was investigated. Studies with chelating agents were consistent with a requirement of metal ions for enzyme activity, and the use of 8-hydroxyquinoline-5-sulfonic acid suggested that Zn2+ was present in the enzyme. The low activity detected in metal-free apoporphobilinogen synthase was attributed to adventitious metal ions. Addition of Zn2+ to the apoenzyme completely restored enzyme activity if the essential sulfhydryl groups on the enzyme were first reduced with sulfhydryl reagents. It does not follow necessarily from this observation that Zn2+ forms a bond with a sulfhydryl group in the enzyme. However, we also observed that Zn2+ did not bind to the enzyme unless the essential cysteinyl residues were reduced. We have concluded that the octameric enzyme contains 4 g atoms of Zn2+/mol from our enzyme activity measurements and binding studies. Alkylation of the enzyme resulted in a marked reduction in the binding of Zn2+ to the enzyme. These observations are consistent with the suggestion that the interaction of the Zn2+ ions with the enzyme occurs with sulfhydryl groups at the active site. It appears that Zn2+ does not participate in substrate binding nor in the maintenance of the quaternary structure of the enzyme. Possible mechanistic roles for Zn2+ in porphobilinogen synthase are discussed. It should be noted that Cd2+ was the only other element found which restored activity to the apoenzyme.

  12. Potential Application of N-Carbamoyl-β-Alanine Amidohydrolase from Agrobacterium tumefaciens C58 for β-Amino Acid Production▿

    PubMed Central

    Martínez-Gómez, Ana Isabel; Martínez-Rodríguez, Sergio; Pozo-Dengra, Joaquín; Tessaro, Davide; Servi, Stefano; Clemente-Jiménez, Josefa María; Rodríguez-Vico, Felipe; Las Heras-Vázquez, Francisco Javier

    2009-01-01

    An N-carbamoyl-β-alanine amidohydrolase of industrial interest from Agrobacterium tumefaciens C58 (βcarAt) has been characterized. βcarAt is most active at 30°C and pH 8.0 with N-carbamoyl-β-alanine as a substrate. The purified enzyme is completely inactivated by the metal-chelating agent 8-hydroxyquinoline-5-sulfonic acid (HQSA), and activity is restored by the addition of divalent metal ions, such as Mn2+, Ni2+, and Co2+. The native enzyme is a homodimer with a molecular mass of 90 kDa from pH 5.5 to 9.0. The enzyme has a broad substrate spectrum and hydrolyzes nonsubstituted N-carbamoyl-α-, -β-, -γ-, and -δ-amino acids, with the greatest catalytic efficiency for N-carbamoyl-β-alanine. βcarAt also recognizes substrate analogues substituted with sulfonic and phosphonic acid groups to produce the β-amino acids taurine and ciliatine, respectively. βcarAt is able to produce monosubstituted β2- and β3-amino acids, showing better catalytic efficiency (kcat/Km) for the production of the former. For both types of monosubstituted substrates, the enzyme hydrolyzes N-carbamoyl-β-amino acids with a short aliphatic side chain better than those with aromatic rings. These properties make βcarAt an outstanding candidate for application in the biotechnology industry. PMID:19011069

  13. A microscale solid-phase extraction poly(dimethylsiloxane) chip for enrichment and fluorescent detection of metal ions.

    PubMed

    Xue, Shuhua; Liu, Yan; Li, Hai-Fang; Uchiyama, Katsumi; Lin, Jin-Ming

    2013-11-15

    A rapid and simple enrichment system was developed on microfluidic chip which was integrated with on-line complexing and fluorescence detection. Microparticles of ion-exchange resin were trapped into the microchannel by a fabricated weir-structure in the end of the microchannel to construct a micro-solid-phase extraction (μ-SPE) device. Some commonly existing metal ions in environment were served as models to evaluate the performance of the proposed microdevice, in combination with on-line derivatization with 8-hydroxyquinolin-5-sulfonic acid (HQS) and fluorescence detection. The concentration and pH value of HQS solution were optimized for metal-HQS fluorescent derivatization. The parameters, which affected the efficiency of the developed method, including composition and concentration of eluent, pH value and the flow rate of HQS solution and elution, were also investigated. Under the optimal conditions, Ca(2+), Mg(2+), Zn(2+) and Pb(2+) were successfully determined by the μ-SPE device on-chip. The experimental enrichment factors for Ca(2+), Mg(2+), Zn(2+) and Pb(2+) were up to 520, 565, 578 and 487 folds, respectively.

  14. Mn(2+) in D-Glucosaminate Dehydratase from Pseudomonas fluorescens.

    PubMed

    Iwamoto, R; Nakura, S

    1993-01-01

    D-Glucosaminate (D-GlcNA) dehydratase from Pseudomonas fluorescens was inhibited stoichiometrically by metal-chelating agents (EDTA, 8-hydroxyquinoline-5-sulfonic acid, α,α'-dipyridyl and o-phenan-throline). The activity of EDTA-treated enzyme was restored by incubation with Mn(2+) (0.4mM) or Ca(2+) (2mM) in the presence of pyridoxal 5'-phosphate (PLP, 0.2mM) in veronal buffer (VB, 40 mM, pH 8) at 37°C for 30 min. The atomic absorption spectrum of the native enzyme showed that the enzyme contained 1 mol of Mn(2+) per mole of enzyme. Although the EDTA-treated enzyme was unstable at 4°C, addition of Mn(2+) and PLP to the solution of the EDTA-treated enzyme prevented the inactivation. The Km of the restored enzyme for D-GlcNA was somewhat lower than that of the original enzyme. However, the Km for PLP increased 14-fold. These results suggest that D-GlcNA dehydratase contains Mn(2+) near the PLP-binding site, and the metal ion appears to stabilize the structure of the active site.

  15. Potential application of N-carbamoyl-beta-alanine amidohydrolase from Agrobacterium tumefaciens C58 for beta-amino acid production.

    PubMed

    Martínez-Gómez, Ana Isabel; Martínez-Rodríguez, Sergio; Pozo-Dengra, Joaquín; Tessaro, Davide; Servi, Stefano; Clemente-Jiménez, Josefa María; Rodríguez-Vico, Felipe; Las Heras-Vázquez, Francisco Javier

    2009-01-01

    An N-carbamoyl-beta-alanine amidohydrolase of industrial interest from Agrobacterium tumefaciens C58 (beta car(At)) has been characterized. Beta car(At) is most active at 30 degrees C and pH 8.0 with N-carbamoyl-beta-alanine as a substrate. The purified enzyme is completely inactivated by the metal-chelating agent 8-hydroxyquinoline-5-sulfonic acid (HQSA), and activity is restored by the addition of divalent metal ions, such as Mn(2+), Ni(2+), and Co(2+). The native enzyme is a homodimer with a molecular mass of 90 kDa from pH 5.5 to 9.0. The enzyme has a broad substrate spectrum and hydrolyzes nonsubstituted N-carbamoyl-alpha-, -beta-, -gamma-, and -delta-amino acids, with the greatest catalytic efficiency for N-carbamoyl-beta-alanine. Beta car(At) also recognizes substrate analogues substituted with sulfonic and phosphonic acid groups to produce the beta-amino acids taurine and ciliatine, respectively. Beta car(At) is able to produce monosubstituted beta(2)- and beta(3)-amino acids, showing better catalytic efficiency (k(cat)/K(m)) for the production of the former. For both types of monosubstituted substrates, the enzyme hydrolyzes N-carbamoyl-beta-amino acids with a short aliphatic side chain better than those with aromatic rings. These properties make beta car(At) an outstanding candidate for application in the biotechnology industry.

  16. The relationship between the rate of chelator-induced zinc efflux from erythrocytes and zinc status.

    PubMed

    Fischer, P W; Bettger, W J

    1992-09-01

    The rate of zinc (Zn) release from rat erythrocytes incubated in buffers containing a variety of chelators was measured. Only o-phenanthroline, 8-hydroxyquinoline-5-sulfonate, and EDTA caused detectable Zn release. The relationship between the rate of this release in the presence of o-phenanthroline and Zn status was determined in rats. Rats were fed one of the following: a modified AIN-76 diet providing 46 mumol (3 mg) Zn per kg of diet, a pair-fed diet providing 459 mumol (30 mg)/kg, or the previous diet fed ad lib. Animals were sacrificed at 2-wk intervals for 12 wk, and the Zn efflux rate, plasma, liver, and femur Zn concentrations were determined. The efflux rate was lower in erythrocytes taken from the rats fed the low-Zn diet. The efflux rate was also well correlated with femur Zn (r = 0.509, n = 98, p < 0.0001). A poorer correlation was observed with plasma Zn in the rats. Correlations also were determined between efflux rates and plasma Zn levels in human subjects. There was a significant correlation only in the males. In was concluded that the Zn efflux rate from erythrocytes incubated in the presence of o-phenanthroline is related to Zn status but is not sensitive enough to be a useful index of this status.

  17. Utilization of TiO2 deposited on glass plates for removal of metals from aqueous wastes

    PubMed

    Hilmi; Luong; Nguyen

    1999-02-01

    Glass plates coated with TiO2 were used in a photocatalytic process to collect mercury, lead, copper and cadmium from aqueous solutions containing individual metals and mixtures. Stripping voltammetry, verified to achieve 1-10 ppb detection limits, was used to show that individual metals at concentrations of 1000 to 5200 ppb were reduced to undetectable levels in 3 to 55 min. Capillary electrophoresis (CE) with 8-hydroxyquinoline-5-sulfonic acid as complexing agent was used when appropriate, since it could quantitate all four metals under study in one run although it was less sensitive. It was demonstrated that 100 mL solutions containing 10 ppm of each of the four metals could be treated with a 10 cm2 TiO2-coated plate to leave undetectable metal concentrations in one hour. Stripping voltammetry using carbon electrodes coated with mercury films was estimated to generate daily about 1.1 L of aqueous waste containing 0.1 ppm of each metal. The results indicate the feasibility of assembling an apparatus capable of treating the waste generated by stripping voltammetry to render the latter suitable for routine on-site analyses without environmental concern. Data were also obtained to show the effectiveness in treating silver containing solutions, indicating suitability of the photocatalytic process in treating photographic processing wastes.

  18. Purification and partial characterization of a Nocardia brasiliensis extracellular protease.

    PubMed

    Zlotnik, H; Schramm, V L; Buckley, H R

    1984-02-01

    Nocardia brasiliensis possess proteolytic activities that can be readily detected in a variety of media. In a modified formulation of a growth medium originally used for Streptomyces aureofaciens, N. brasiliensis was found to secrete proteolytic enzymes, one of which was capable of hydrolyzing casein. This enzyme was purified to homogeneity from cell-free culture filtrates of N. brasiliensis. The purification procedure included ion-exchange chromatography on carboxymethyl-Sepharose, gel filtration on Sephadex G-100, and affinity chromatography, using a hemoglobin-Sepharose resin. The molecular weight of the N. brasiliensis protease was found to be 25,000 by gel filtration and 35,000 by sodium dodecyl sulfate-discontinuous gel electrophoresis. The enzyme is inhibited by o-phenanthroline and 8-hydroxyquinoline-5-sulfonic acid but is not affected by EDTA. Average values for its kinetic parameters were 0.288 mumol of hemoglobin solubilized per min per mg of enzyme for Vmax and 0.76 mM for Km, using hemoglobin as the substrate.

  19. Voltammetric analysis with the use of a novel electro-polymerised graphene-nafion film modified glassy carbon electrode: simultaneous analysis of noxious nitroaniline isomers.

    PubMed

    Lin, Xiaoyun; Ni, Yongnian; Kokot, Serge

    2012-12-01

    A new modified electrode was constructed by the electro-polymerization of 7-[(2,4-dihydroxy-5-carboxybenzene)azo]-8-hydroxyquinoline-5-sulfonic acid (DHCBAQS) at a graphene-nafion modified glassy carbon electrode (GCE). The construction process was performed stepwise and at each step the electrochemical characteristics were investigated particularly with respect to the oxidation of the three noxious analytes, 2-nitroaniline (2-NA), 3-nitroaniline (3-NA), 4-nitroaniline (4-NA); the electrode treated with the fluorescence reagent DHCBAQS performed best. At this electrode, the differential pulse voltammetry peak currents of the three isomers increased linearly with their concentrations in the range of 0.05-0.60 μg mL(-1), respectively, and their corresponding limits of detection (LODs) were all about 0.022 μg mL(-1). Furthermore, satisfactory results were obtained when this electrode was applied for the simultaneous quantitative analysis of the nitroaniline isomer mixtures by Principal component regression (PCR) and Partial least squares (PLS) as calibration methods (relative prediction error (PRE(T)) - 9.04% and 9.23%) and average recoveries (101.0% and 101.7%), respectively. The above novel poly-DHCBAQS/graphene-nafion/GCE was successfully employed for the simultaneous analysis of the three noxious nitroaniline isomers in water and sewage samples.

  20. Purification, characterization and immunocytochemical localization of mouse kidney carnosinase.

    PubMed

    Margolis, F L; Grillo, M; Grannot-Reisfeld, N; Farbman, A I

    1983-05-18

    Mouse kidney carnosinase (aminoacyl-L-histidine hydrolase, EC 3.4.13.3) has been isolated, the amino acid composition determined and antiserum prepared against it. The apparent subunit molecular weight is 58 000, which increases to 112 000 on crosslinking. Carnosinase is sensitive to chelating agents and is 50% inhibited by 0.3 microM EDTA, 35 microM o-phenanthroline, or 35 microM 8-hydroxyquinoline-5-sulfonic acid. The Km for carnosine is 60 microM. Anserine is a poor substrate and homocarnosine a non-substrate, with Ki values of 37 and 17 microM, respectively. Mn2+ shifts the Km for carnosine to approx. 2 mM and increases the Vmax about 50%. The specific antiserum discriminates between this carnosinase and a second carnosinase activity which is absolutely dependent on Mn2+ for activity (Margolis, F.L., Grillo, M., Brown, C.E., Williams, T.H., Pitcher, R.G. and Elgar, G.J. (1979) Biochim. Biophys. Acta 570, 311-323). Immunocytochemistry with this antiserum has demonstrated carnosinase to be localized in proximal tubules of kidney, glandular cells of uterus and nasal olfactory mucosa and in vomeronasal and certain other nerve pathways.

  1. Sequential injection fluorimetric determination of Sn in juices of canned fruits.

    PubMed

    Morte, Elane S Boa; Korn, Maria Graças A; Saraiva, M Lúcia M F S; Lima, José L F C; Pinto, Paula C A G

    2009-09-15

    The present work describes the development of a fast and robust sequential injection fluorimetric procedure for the determination of Sn in juices of canned fruits. The developed automatic methodology is based on the complexation of Sn with 8-hydroxyquinoline-5-sulfonic acid (HQSA) to form a fluorimetric product (lambda(exc)=354 nm; lambda(em)=510 nm). The influence of dimethylsulfoxide (DMSO) and cetylpyridinium bromide (CPB) on the sensitivity of the fluorimetric determination was evaluated. Linear calibration plots were obtained for Sn concentrations between 1 and 10 mg L(-1), with a detection limit of 0.38 mg L(-1). In each analytical cycle 0.006 mg of HQSA and 0.47 mg of CPB were consumed and 1.5 mL of effluent was generated. The developed methodology was applied to the determination of Sn in juices of canned fruits and the results complied with those furnished by an electrothermal atomic absorption spectrometry comparison procedure, with relative deviations lower than 5.2%. The automatic procedure exhibited good precision (R.S.D.<1.4%) and the sampling rate was about 70 determinations per hour.

  2. Exploitation of a single interface flow system for on-line aqueous biphasic extraction.

    PubMed

    Silvestre, Cristina I C; Rodrigues, Sofia; Santos, João L M; Lima, José L F C; Zagatto, Elias A G

    2010-06-15

    The exploitation of aqueous biphasic extraction is proposed for the first time in flow analysis. This extraction strategy stands out for being environmentally attractive since it is based in the utilization of two immiscible phases that are intrinsically aqueous. The organic solvents of the traditional liquid-liquid extractions are no longer used, being replaced by non-toxic, non-flammable and non-volatile ones. A single interface flow analysis (SIFA) system was implemented to carry out the extraction process due to its favourable operational characteristics that include the high automation level and simplicity of operation, the establishment of a dynamic interface where the mass transfer occurred between the two immiscible aqueous phases, and the versatile control over the extraction process namely the extraction time. The application selected to demonstrate the feasibility of SIFA to perform this aqueous biphasic extraction was the pre-concentration of lead. After extraction, lead reacted with 8-hydroxyquinoline-5-sulfonic acid and the resulting product was determined by a fluorimetric detector included in the flow manifold. Therefore, the SIFA single interface was used both as extraction (enrichment) and reaction interface.

  3. Purification and partial characterization of a Nocardia brasiliensis extracellular protease.

    PubMed Central

    Zlotnik, H; Schramm, V L; Buckley, H R

    1984-01-01

    Nocardia brasiliensis possess proteolytic activities that can be readily detected in a variety of media. In a modified formulation of a growth medium originally used for Streptomyces aureofaciens, N. brasiliensis was found to secrete proteolytic enzymes, one of which was capable of hydrolyzing casein. This enzyme was purified to homogeneity from cell-free culture filtrates of N. brasiliensis. The purification procedure included ion-exchange chromatography on carboxymethyl-Sepharose, gel filtration on Sephadex G-100, and affinity chromatography, using a hemoglobin-Sepharose resin. The molecular weight of the N. brasiliensis protease was found to be 25,000 by gel filtration and 35,000 by sodium dodecyl sulfate-discontinuous gel electrophoresis. The enzyme is inhibited by o-phenanthroline and 8-hydroxyquinoline-5-sulfonic acid but is not affected by EDTA. Average values for its kinetic parameters were 0.288 mumol of hemoglobin solubilized per min per mg of enzyme for Vmax and 0.76 mM for Km, using hemoglobin as the substrate. Images PMID:6363390

  4. The effect of the hole injection layer on the performance of single layer organic light-emitting diodes

    SciTech Connect

    Wenjin, Zeng; Ran, Bi; Hongmei, Zhang E-mail: iamwhuang@njupt.edu.cn; Wei, Huang E-mail: iamwhuang@njupt.edu.cn

    2014-12-14

    Efficient single-layer organic light-emitting diodes (OLEDs) were reported based on a green fluorescent dye 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7–tetramethyl-1H,5H,11H-(1) benzopyropyrano (6,7-8-I,j)quinolizin-11-one (C545T). Herein, poly(3,4-ethylenedioxy thiophene) poly(styrene sulfonate) were, respectively, applied as the injection layer for comparison. The hole transport properties of the emission layer with different hole injection materials are well investigated via current-voltage measurement. It was clearly found that the hole injection layers (HILs) play an important role in the adjustment of the electron/hole injection to attain transport balance of charge carriers in the single emission layer of OLEDs with electron-transporting host. The layer of tris-(8-hydroxyquinoline) aluminum played a dual role of host and electron-transporting materials within the emission layer. Therefore, appropriate selection of hole injection layer is a key factor to achieve high efficiency OLEDs with single emission layer.

  5. Role-allocated combination of two types of hydrogen bonds towards constructing a breathing diamondoid porous organic salt.

    PubMed

    Yamamoto, Atsushi; Hasegawa, Tetsuya; Hamada, Tomoya; Hirukawa, Tomofumi; Hisaki, Ichiro; Miyata, Mikiji; Tohnai, Norimitsu

    2013-02-25

    A diamondoid porous organic salt (d-POS) composed of 8-hydroxyquinoline-5-sulfonic acid (HQS) and triphenylmethylamine (TPMA) shows reversible structure contraction and expansion ("breathing") in response to guest desorption and adsorption. This flexible structure is designed hierarchically by utilizing two different types of hydrogen bonds. X-ray crystallographic analysis reveals that the two types of hydrogen bonds are formed separately to play respective roles for constructing the d-POS. The strong charge-assisted hydrogen bond between the sulfonate anion of HQS and the ammonium cation of TPMA serves as a static node to provide a supramolecular cluster for a building block. In contrast, the complementary neutral hydrogen bond between the hydroxyl and quinolyl groups of HQS acts as a dynamic linker to connect the clusters. Consequently, these two types of hydrogen bonds yield the d-POS with one-dimensional channels through the formation of diamondoid networks. We clarify that the d-POS undergoes dynamic structure transformation that originates in the cleavage and reformation of the complementary neutral hydrogen bond during guest desorption and adsorption. From the comparative studies, it is also demonstrated that applying the complementary neutral hydrogen bond in the d-POS provides significant advantages in terms of the responsivity of the structure over applying other weak noncovalent interactions for the connection of the clusters. Furthermore, the resultant d-POS also modulates fluorescent profiles dynamically responsive to guest adsorption and desorption.

  6. XPS investigation of the photon degradation of Znq2 green organic phosphor

    NASA Astrophysics Data System (ADS)

    Duvenhage, Mart-Mari; Terblans, Jacobus J.; Ntwaeaborwa, Martin; Swart, Hendrik C.

    2016-01-01

    By substituting Al with Zn to form bis-(8-hydroxyquinoline) zinc (Znq2), the device performance of organic light emitting diodes (OLED) can be improved. Znq2 also has a more closed packed crystal structure that makes it less vulnerable to reactions with atmospheric oxygen and moisture leading to more stable and longer lasting devices. In this work the effect of photon degradation of Znq2 in air was investigated. Znq2 powder was synthesized using a co-precipitation method and recrystallized in acetone. The structure of the sample was confirmed to be Znq2·2H2O by X-ray diffraction. The photoluminescence (PL) emission data also confirmed that the Znq2·2H2O crystal form of Znq2 was present. To study the photon degradation, the sample was irradiated with a UV lamp for 400 h. The emission data was collected and the change in PL intensity with time was monitored. X-ray photoelectron spectroscopy was performed on the as prepared and photon-degraded samples. The Zn2p and N1s peaks showed no change after degradation. The O1s and C1s peaks confirmed that the phenoxide ring ruptured and that C=O and C-O species had formed.

  7. Simulations of emission from microcavity tandem organic light-emitting diodes

    SciTech Connect

    Biswas, Rana; Xu, Chun; Zhao, Weijun; Liu, Rui; Shinar, Ruth; Shinar, Joseph

    2011-01-01

    Microcavity tandem organic light-emitting diodes (OLEDs) are simulated and compared to experimental results. The simulations are based on two complementary techniques: rigorous finite element solutions of Maxwell's equations and Fourier space scattering matrix solutions. A narrowing and blue shift of the emission spectrum relative to the noncavity single unit OLED is obtained both theoretically and experimentally. In the simulations, a distribution of emitting sources is placed near the interface of the electron transport layer tris(8-hydroxyquinoline) Al (Alq{sub 3}) and the hole transport layer (N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine) ({alpha}-NPB). Far-field electric field intensities are simulated. The simulated widths of the emission peaks also agree with the experimental results. The simulations of the 2-unit tandem OLEDs shifted the emission to shorter wavelength, in agreement with experimental measurements. The emission spectra's dependence on individual layer thicknesses also agreed well with measurements. Approaches to simulate and improve the light emission intensity from these OLEDs, in particular for white OLEDs, are discussed.

  8. Determination of dissolved aluminum in water samples

    USGS Publications Warehouse

    Afifi, A.A.

    1983-01-01

    A technique has been modified for determination of a wide range of concentrations of dissolved aluminum (Al) in water and has been tested. In this technique, aluminum is complexed with 8-hydroxyquinoline at pH 8.3 to minimize interferences, then extracted with methyl isobutyl ketone (MIBK). The extract is analyzed colorimetrically at 395 nm. This technique is used to analyze two forms of monomeric Al, nonlabile (organic complexes) and labile (free, Al, Al sulfate, fluoride and hydroxide complexes). A detection limit 2 ug/L is possible with 25-ml samples and 10-ml extracts. The detection limit can be decreased by increasing the volume of the sample and (or) decreasing the volume of the methyl isobutyl ketone extract. The analytical uncertainty of this method is approximately + or - 5 percent. The standard addition technique provides a recovery test for this technique and ensures precision in samples of low Al concentrations. The average percentage recovery of the added Al plus the amount originally present was 99 percent. Data obtained from analyses of filtered standard solutions indicated that Al is adsorbed on various types of filters. However, the relationship between Al concentrations and adsorption remains linear. A test on standard solutions also indicated that Al is not adsorbed on nitric acid-washed polyethylene and polypropylene bottle wells. (USGS)

  9. Bias-induced photoluminescence quenching of single colloidal quantum dots embedded in organic semiconductors.

    PubMed

    Huang, Hao; Dorn, August; Nair, Gautham P; Bulović, Vladimir; Bawendi, Moungi G

    2007-12-01

    We demonstrate reversible quenching of the photoluminescence from single CdSe/ZnS colloidal quantum dots embedded in thin films of the molecular organic semiconductor N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) in a layered device structure. Our analysis, based on current and charge carrier density, points toward field ionization as the dominant photoluminescence quenching mechanism. Blinking traces from individual quantum dots reveal that the photoluminescence amplitude decreases continuously as a function of increasing forward bias even at the single quantum dot level. In addition, we show that quantum dot photoluminescence is quenched by aluminum tris(8-hydroxyquinoline) (Alq3) in chloroform solutions as well as in thin solid films of Alq3 whereas TPD has little effect. This highlights the importance of chemical compatibility between semiconductor nanocrystals and surrounding organic semiconductors. Our study helps elucidate elementary interactions between quantum dots and organic semiconductors, knowledge needed for designing efficient quantum dot organic optoelectronic devices. PMID:18034504

  10. Sharp green electroluminescence from 1H-pyrazolo[3,4-b]quinoline-based light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Tao, Y. T.; Balasubramaniam, E.; Danel, A.; Jarosz, B.; Tomasik, P.

    2000-09-01

    A multilayer organic light-emitting diode was fabricated using a fluorescent compound {6-N,N-diethylamino-1-methyl-3-phenyl-1H-pyrazolo[3,4-b]quinoline} (PAQ-NEt2) doped into the hole-transporting layer of NPB {4,4'-bis[N-(1-naphthyl-1-)-N-phenyl-amino]-biphenyl}, with the TPBI {2,2',2″-(1,3,5-phenylene)tris[1-phenyl-1H-benzimidazole]} as an electrontransporting material. At 16% PAQ-NEt2 doping concentration, the device gave a sharp, bright, and efficient green electroluminescence (EL) peaked at around 530 nm. The full width at half maximum of the EL is 60 nm, which is 60% of the green emission from typical NPB/AlQ [where AlQ=tris(8-hydroxyquinoline) aluminum] device. For the same concentration, a maximum luminance of 37 000 cd/m2 was obtained at 10.0 V and the maximum power, luminescence, and external quantum efficiencies were obtained 4.2 lm/W, 6.0 cd/A, and 1.6%, respectively, at 5.0 V.

  11. The solution structure of the copper clioquinol complex.

    PubMed

    Pushie, M Jake; Nienaber, Kurt H; Summers, Kelly L; Cotelesage, Julien J H; Ponomarenko, Olena; Nichol, Helen K; Pickering, Ingrid J; George, Graham N

    2014-04-01

    Clioquinol (5-chloro-7-iodo-8-hydroxyquinoline) recently has shown promising results in the treatment of Alzheimer's disease and in cancer therapy, both of which also are thought to be due to clioquinol's ability as a lipophilic copper chelator. Previously, clioquinol was used as an anti-fungal and anti-protozoal drug that was responsible for an epidemic of subacute myelo-optic neuropathy (SMON) in Japan during the 1960s, probably a myeloneuropathy arising from a clioquinol-induced copper deficiency. Previous X-ray absorption spectroscopy of solutions of copper chelates of clioquinol suggested unusual coordination chemistry. Here we use a combination of electron paramagnetic, UV-visible and X-ray absorption spectroscopies to provide clarification of the chelation chemistry between clioquinol and copper. We find that the solution structures for the copper complexes formed with stoichiometric and excess clioquinol are conventional 8-hydroxyquinolate chelates. Thus, the promise of clioquinol in new treatments for Alzheimer's disease and in cancer therapy is not likely to be due to any novel chelation chemistry, but rather due to other factors including the high lipophilicity of the free ligand and chelate complexes.

  12. Influences of Alq3 as electron extraction layer instead of Ca on the photo-stability of organic solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Zhiyong; Tian, Miaomiao; Wang, Ning

    2014-03-01

    Calcium (Ca) is not a desirable candidate as electron extraction layer (EEL) for long-term stability organic photovoltaics (OPVs) on account of its nature of active metal. In this paper, we has selected thieno[3,4-b]thiophene/benzodithiophene (PTB7) and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) as donor and acceptor, respectively, and the device architecture is Glass/ITO/poly(ethylenedioxythiophene):polystyrene sulphonate (PEDOT:PSS)/PTB7:PC71BM/EEL/Aluminum. For comparison, tris (8-hydroxyquinoline) aluminum (Alq3) and Ca were used as EEL to reveal their influence on the performance [power conversion efficiency (PCE), short-circuit current density (JSC), open-circuit voltage (VOC) and fill factor (FF)] of the OPVs. As a result, PCE of the device with Ca as EEL rapidly reduced over 60% after three days due to the poor stability of Ca. The device with Alq3 as EEL shows favorable stability owing to the PCE moderate declined less than 30% after one month. Furthermore, PCE of the device with Alq3 as EEL was fully comparable to that with Ca as EEL. Our results indicate that Alq3 is an alternative candidate for high-performance and long-term photo-stability OPVs.

  13. Titanium complex formation of organic ligands in titania gels.

    PubMed

    Nishikiori, Hiromasa; Todoroki, Kenta; Setiawan, Rudi Agus; Teshima, Katsuya; Fujii, Tsuneo; Satozono, Hiroshi

    2015-01-27

    Thin films of organic ligand-dispersing titania gels were prepared from titanium alkoxide sols containing ligand molecules by steam treatment without heating. The formation of the ligand-titanium complex and the photoinduced electron transfer process in the systems were investigated by photoelectrochemical measurements. The complex was formed between the 8-hydroxyquinoline (HQ) and titanium species, such as the titanium ion, on the titania nanoparticle surface through the oxygen and nitrogen atoms of the quinolate. A photocurrent was observed in the electrodes containing the complex due to the electron injection from the LUMO of the complex into the titania conduction band. A bidentate ligand, 2,3-dihydroxynaphthalene (DHN), formed the complex on the titania surface through dehydration between its two hydroxyl groups of DHN and two TiOH groups of the titania. The electron injection from the HOMO of DHN to the titania conduction band was observed during light irradiation. This direct electron injection was more effective than the two-step electron injection.

  14. Binary and ternary copper(II) complexes of a tridentate ONS ligand derived from 2-aminochromone-3 carboxaldehyde and thiosemicarbazide: Synthesis, spectral studies and antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Shebl, Magdy; Ibrahim, M. A.; Khalil, Saied M. E.; Stefan, S. L.; Habib, H.

    2013-11-01

    A tridentate ONS donor ligand, HL, was synthesized by the condensation of 2-aminochromone-3-carboxaldehyde with thiosemicarbazide. The structure of the ligand was elucidated by elemental analyses, IR, 1H and 13C NMR, electronic and mass spectra. Reaction of the ligand with several copper(II) salts, including AcO-, NO3-, SO42-, Cl-, Br- and ClO4- afforded different metal complexes that reflect the non-coordinating or weakly coordinating power of the ClO4- and Br- anions as compared to the strongly coordinating power of AcO-, SO42-, Cl- and NO3- anions. Also, the ligand was allowed to react with Cu(II) ion in the presence of a secondary ligand (L‧) [N,O-donor; 8-hydroxyquinoline or N,N-donor; 1,10-phenanthroline]. Characterization and structure elucidation of the prepared complexes were achieved by elemental and thermal analyses, IR, electronic, mass and EPR spectra as well as conductivity and magnetic susceptibility measurements. The EPR spin Hamiltonian parameters of some complexes were calculated. The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. The ligand and most of its metal complexes showed antibacterial activity towards Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Salmonella typhimurium and Escherichia coli), yeast (Candida albicans) and fungus (Aspergillus fumigatus).

  15. Separation and preconcentration of trace amounts of aluminum ions in surface water samples using different analytical techniques.

    PubMed

    Khan, Sumaira; Kazi, Tasneem G; Baig, Jameel A; Kolachi, Nida F; Afridi, Hassan I; Shah, Abdul Q; Kandhro, Ghulam A; Kumar, Sham

    2009-11-15

    A separation/preconcentration of aluminum (III) (Al(3+)) has been developed to overcome the problem of high matrix species, which may interfere with the determination of trace quantity of Al(3+) in natural water samples. The separation of Al(3+) in water samples was carried out from interfering cations by complexing them with 2-methyle 8-hyroxyquinoline (quinaldine) on activated silica. Whereas the separated trace amounts of Al(3+) was preconcentrated by cloud point extraction (CPE), as prior step to its determination by spectrofluorimetry (SPF) and flame atomic absorption spectrometry (FAAS). The Al(3+) react with 8-hydroxyquinoline (oxine) and then entrapped in non-ionic surfactant Triton X-114. The main factors affecting CPE efficiency, such as pH of sample solution, concentration of oxine and Triton X-114, equilibration temperature and time period for shaking were investigated in detail. The validity of separation/preconcentration of Al(3+) was checked by certified reference material of water (SRM-1643e). After optimization of the complexation and extraction conditions, a preconcentration factor of 20 was obtained for Al(3+) in 10 mL of natural water samples. The relative standard deviation for 6 replicates containing 100 microg L(-1) of Al(3+) was 5.41 and 4.53% for SPF and FAAS, respectively. The proposed method has been applied for determination of trace amount of Al(3+) in natural water samples with satisfactory results. PMID:19782206

  16. Prediction and measurement of effect of chelating selectivity on precipitation reactions.

    PubMed

    Kelly, J J; Sutton, D C

    1966-11-01

    A theoretical treatment of precipitation equilibrium in the presence of a chelating agent has been expanded to include the common ion effect on precipitation reactions. The extent of precipitation can be predicted over the full range of pH for any metal for which the solubility product of the precipitate and the stability constants for a complex are known. The expanded equation has been used in this investigation to predict the extent of precipitation for several metals in the presence of ethylenediaminetetra-acetic acid (EDTA) with common précipitants such as hydroxide, oxalate, sulphate, sulphide and 8-hydroxyquinoline, but may be applied to any system containing other chelating agents. The limits of precipitation in terms of pM', the negative logarithm of the concentration of unprecipitated metal ion, are presented graphically as a function of pH for a system containing axed amounts of precipitating and complexing agents. Measurements for observed reactions at two pH levels, 5 and 10, are compared with the calculated predictions of the equation. Thirty-five metals were investigated.

  17. A sequential injection system for the spectrophotometric determination of calcium, magnesium and alkalinity in water samples.

    PubMed

    Mesquita, Raquel B R; Rangel, António O S S

    2004-08-01

    A sequential injection methodology for the spectrophotometric determination of calcium, magnesium and alkalinity in water samples is proposed. A single manifold is used for the determination of the three analytes, and the same protocol sequence allows the sequential determination of calcium and magnesium (the sum corresponds to the water hardness). The determination of both metals is based on their reaction with cresolphtalein complexone; mutual interference is minimized by using 8-hydroxyquinoline for the determination of calcium and ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) for the determination of magnesium. Alkalinity determination is based on a reaction with acetic acid, and corresponding color change of Bromcresol Green. Working ranges of 0.5 - 5 mg dm(-3) for Ca, 0.5 - 10 mg dm(-3) for Mg, and 10 - 100 mg HCO3- dm(-3), for alkalinity have been achieved. The results for water samples were comparable to those of the reference methods and to a certified reference water sample. RSDs lower than 5% were obtained, a low reagent consumption and a reduced volume of effluent have been accomplished. The determination rate for calcium and magnesium is 80 h(-1), corresponding to 40 h(-1) per element, while 65 determinations of alkalinity per hour could be carried out.

  18. An organic light-emitting devices of highly efficient white phosphor using an electron/exciton blocker

    NASA Astrophysics Data System (ADS)

    Jiang, Wen-Long; Ding, Gui-Ying; Wang, Jin; Wang, Jing; Wang, Li-Zhong; Chang, Xi; Han, Qiang; Wang, Hong-Mei; Zhao, Xiao-Hong

    2008-01-01

    Highly efficient white phosphorescent organic light-emitting devices (WOLEDs) was fabricated using an electron/exciton blocker. The device structure is ITO/2T-NATA(25 nm)/ NPBX(25-dnm)/CBP:5%Ir(ppy)3:0.5%Rubrene(8 nm)/NPBX(dnm)/DPVBi(30 nm)/TPBi(20 nm)/Alq(10nm)/LiF(1nm)/Al, in which N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1, 1'-biphenyl-4,4'-diamine (NPBX) functions as a hole transport layer and electron/exciton blocker, 4,4,N,N'-dicarbazolebiphenyl (CBP) is host, 4,4'-bis(2,2-diphenyl vinyl)-1,1'-biphenyl (DPVBi) is blue fluorescent dye, 5,6,11,12,-tetraphenylnaphthacene (rubrene) is fluorescent dye, factris (2-phenylpyridine) iridium (Ir(ppy)3) is phosphorescent sensitizer and tris(8-hydroxyquinoline) aluminum (Alq3) is an electron transport layer. The WOLEDs have obtained white light emission by adjusting the thickness of NPBX, when the concentration of Ir(ppy)3 is 5-wt% and rubrene is 0.5-wt%, respectively, the thickness of the doped emissive layer is 8 nm, the WOLEDs show a maximum luminous efficiency is 11.2 cd/A with d of 10 nm at 7 V and a maximum luminance of 28170 cd/m2 at 17 V, the CIE coordinates is (0.37.0.42), which is in white region.

  19. ET-AAS determination of aluminium in dialysis concentrates after continuous flow solvent extraction.

    PubMed

    Komárek, J; Cervenka, R; Růzicka, T; Kubán, V

    2007-11-01

    Conditions of a continuous flow extraction (CFE) of aluminium acetylacetonate in acetylacetone and aluminium 8-hydroxyquinolinate into methylisobutylketone (lengths of reaction and extraction coils, flow rates of aqueous and organic phases and their flow rate ratio, pH of aqueous phase, lengths of coils for transport of aqueous and organic phases and effect of salts) were studied. The analytical signal of the aluminium chelates present in the organic phase was measured at 309.3 nm using atomic absorption spectrometry with electrothermal atomization (ET-AAS) at the flow rate ratio F aq/F org=3 for aqueous and organic phases. The five points calibration curves were linear (R2 0.9973 and 0.9987) up to 21 microgl(-1) Al with the limits of detection of 0.3 microgl(-1) and the recovery 100+/-2% and precision of 3% at 2-10-fold dilution of the dialysis concentrates. The acetylacetonate method was applied to the determination of aluminium in real dialysis concentrates. Aluminium in concentrations 5-6 microgl(-1) (R.S.D.s 5-10% in real samples) were found and the results were in the very good agreement with those obtained by an ET-AAS using preconcentration of Al(III) on a Spheron-Salicyl chelating sorbent (absolute and relative differences were under 0.4 microgl(-1) and 8.2%, respectively). PMID:17897803

  20. [Study on the Effects of Alq₃:CsF Composite Cathode Buffer Layer on the Performances of CuPc/C₆₀ Solar Cells].

    PubMed

    Zhao, Huan-bin; Sun, Qin-jun; Zhou, Miao; Gao, Li-yan; Hao, Yu-ying; Shi, Fang

    2016-02-01

    This paper introduces the methods improving the performance and stability of copper-phthalocyanine(CuPc) / fullerene (C₆₀) small molecule solar cells by using tris-(8-hydroxyquinoline) aluminum(Alq₃): cesium fluoride(CsF) composite cathode buffer layer. The device with Alq₃:CsF composite cathode buffer layer with a 4 wt. % CsF at a thickness of 5 nm exhibits a power conversion efficiency (PCE) of up to 0.76%, which is an improvement of 49%, compared to a device with single Alq₃ cathode buffer layer and half-lifetime of the cell in air at ambient circumstance without any encapsulation is almost 9.8 hours, 6 times higher than that of without buffer layer, so the stability is maintained. The main reason of the device performance improvement is that doping of CsF can adjust the interface energy alignment, optimize the electronic transmission characteristics of Alq₃ and improve the short circuit current and the fill factor of the device using ultraviolet-visible absorption, external quantum efficiency and single-electron devices. Placed composite cathode buffer layer devices with different time in the air, by comparing and analyzing current voltage curve, Alq₃:CsF can maintain a good stability as Alq₃. Alq₃:CsF layer can block the diffusion of oxygen and moisture so completely as to improve the lifetime of the device. PMID:27209725

  1. A Noncompetitive Inhibitor for Mycobacterium tuberculosis's Class IIa Fructose 1,6-Bisphosphate Aldolase

    PubMed Central

    Capodagli, Glenn C.; Sedhom, Wafik G.; Jackson, Mary; Ahrendt, Kateri A.; Pegan, Scott D.

    2014-01-01

    Class II fructose 1,6-bisphosphate aldolase (FBA) is an enzyme critical for bacterial, fungal, and protozoan glycolysis/gluconeogenesis. Importantly, humans lack this type of aldolase, having instead a class I FBA that is structurally and mechanistically distinct from class II FBAs. As such, class II FBA is considered a putative pharmacological target for the development of novel antibiotics against pathogenic bacteria such as Mycobacterium tuberculosis, the causative agent for tuberculosis (TB). To date, several competitive class II FBA substrate mimic-styled inhibitors have been developed; however, they lack either specificity, potency, or properties that limit their potential as possible therapeutics. Recently, through the use of enzymatic and structure-based assisted screening, we identified 8-hydroxyquinoline carboxylic acid (HCA) that has an IC50 of 10 ± 1 μM for the class II FBA present in M. tuberculosis (MtFBA). As opposed to previous inhibitors, HCA behaves in a noncompetitive manner, shows no inhibitory properties toward human and rabbit class I FBAs, and possesses anti-TB properties. Furthermore, we were able to determine the crystal structure of HCA bound to MtFBA to 2.1 Å. HCA also demonstrates inhibitory effects for other class II FBAs, including pathogenic bacteria such as methicillin-resistant Staphylococcus aureus. With its broad-spectrum potential, unique inhibitory characteristics, and flexibility of functionalization, the HCA scaffold likely represents an important advancement in the development of class II FBA inhibitors that can serve as viable preclinical candidates. PMID:24325645

  2. Sensitive imaging and effective capture of Cu(2+): Towards highly efficient theranostics of Alzheimer's disease.

    PubMed

    Cui, Zhaowen; Bu, Wenbo; Fan, Wenpei; Zhang, Jiawen; Ni, Dalong; Liu, Yanyan; Wang, Jing; Liu, Jianan; Yao, Zhenwei; Shi, Jianlin

    2016-10-01

    As a distinct feature of Alzheimer's disease (AD), the presence of excess metal ions in the brain is most probably one of the main causative factors for the aggregation of β-Amyloid (Aβ) proteins. The design of nanoprobes for detection and control of ion concentrations will be of great importance in predicting the progression of AD and simultaneously providing effective treatments. Herein, we report the design and synthesis of a novel yet smart nanoprobe that can sensitively detect the Cu(2+) concentration and concurrently capture Cu(2+) both in vitro and in vivo. The designed nanoprobe (UCHQ) combines two main components: upconversion nanoparticles (UCNPs) used for the detection and upconversion luminescence (UCL) imaging of Cu(2+) upon 980 nm exposure and the chelator 8-hydroxyquinoline-2-carboxylic acid (HQC) used for chelating Cu(2+) and AD therapy. The results show that the emission intensity of UCHQ is highly dependent on the Cu(2+) concentrations due to the luminescence resonance energy transfer (LRET) from UCNPs to HQC-bonded Cu(2+). Fascinatingly, the as-constructed UCHQs could be used for UCL imaging of Aβ both in cells and AD mice. Most importantly, UCHQs could not only inhibit the Aβ aggregation-induced apoptosis via capturing overmuch Cu(2+) but also accelerate the nontoxic structural transformation of Aβ. PMID:27454062

  3. Biofunctional constituent isolated from Citrullus colocynthis fruits and structure-activity relationships of its analogues show acaricidal and insecticidal efficacy.

    PubMed

    Jeon, Ju-Hyun; Lee, Hoi-Seon

    2014-08-27

    The acaricidal and insecticidal potential of the active constituent isolated from Citrullus colocynthis fruits and its structurally related analogues was evaluated by performing leaf disk, contact toxicity, and fumigant toxicity bioassays against Tetranychus urticae, Sitophilus oryzae, and Sitophilus zeamais adults. The active constituent of C. colocynthis fruits was isolated by chromatographic techniques and was identified as 4-methylquinoline on the basis of spectroscopic analyses. To investigate the structure-activity relationships, 4-methylquinoline and its structural analogues were tested against mites and two insect pests. On the basis of the LC50 values, 7,8-benzoquinoline was the most effective against T. urticae. Quinoline, 8-hydroxyquinoline, 2-methylquinoline, 4-methylquinoline, 6-methylquinoline, 8-methylquinoline, and 7,8-benzoquinoline showed high insecticidal activities against S. oryzae and S. zeamais regardless of the application method. These results indicate that introduction of a functional group into the quinoline skeleton and changing the position of the group have an important influence on the acaricidal and insecticidal activities. Furthermore, 4-methylquinoline isolated from C. colocynthis fruits, along with its structural analogues, could be effective natural pesticides for managing spider mites and stored grain weevils.

  4. Evaluation of different buffered peptone water (BPW) based enrichment broths for detection of Gram-negative foodborne pathogens from various food matrices.

    PubMed

    Margot, H; Zwietering, M H; Joosten, H; O'Mahony, Emer; Stephan, R

    2015-12-01

    This study evaluated the effects of changing the composition of the pre-enrichment medium buffered peptone water (BPW) on the growth of stressed and unstressed Gram-negative foodborne pathogens in a one-broth enrichment strategy. BPW supplemented with an available iron source and sodium pyruvate, along with low levels of 8-hydroxyquinoline and sodium deoxycholate (BPW-S) improved the recovery of desiccated Cronobacter spp. from powdered infant formula. Growth of Salmonella and STEC was comparable in all BPW variants tested for different food matrices. In products with high levels of Gram-negative background flora (e.g. sprouts), the target organisms could not be reliably detected by PCR in any of the BPW variants tested unless the initial level exceeded 10(3) cfu/10 g of sprouts. Based on these results we suggest BPW-S for a one-broth enrichment strategy of stressed Gram-negative foodborne pathogens from dry products. However, a one-broth enrichment strategy based on BPW variants tested in this evaluation is not recommended for produce with a high level of Gram-negative background flora due to very high detection limits. PMID:26267889

  5. Photoluminescence studies of organic phosphor coated diffusing surface using blue inorganic light-emitting diode as excitation source

    NASA Astrophysics Data System (ADS)

    Singh, Gyanendra; Singh Mehta, Dalip

    2013-02-01

    We report the studies on photoluminescence (PL) of organic phosphor coated on a diffusing surface using a blue inorganic light-emitting diode (LED) array as an excitation source. The organic phosphor composite coated diffuser was used to scatter the directional blue light from the LED array. Some of the blue light is absorbed by the organic phosphor composite and the phosphor molecules are excited and re-emit light at longer wavelengths due to the PL process. The output light consists of scattered blue light plus phosphor generated broadband yellow light, thus making white light. The diffuser was made up of a plastic substrate coated with an organic composite of small molecule fluorescent material zinc(II)bis(8-hydroxyquinoline) (Znq2) doped with different percentages of electro-phosphorescent metal complex iridium(III)bis(2-methyldibenzo-[f, h] quinoxaline) (acetylacetonate) ([Ir(MDQ)2(acac)]). By means of changing the concentration and the thickness of the phosphor composite material the colour coordinates of white light were achieved. The CIE coordinates and correlated colour temperature were calculated for various thicknesses and phosphor composite concentrations and the results are reported.

  6. Transfer of Copper from an Amyloid to a Natural Copper-Carrier Peptide with a Specific Mediating Ligand.

    PubMed

    Nguyen, Michel; Bijani, Christian; Martins, Nathalie; Meunier, Bernard; Robert, Anne

    2015-11-16

    The oxidative stress that arises from the catalytic reduction of dioxygen by Cu(II/I)-loaded amyloids is the major pathway for neuron death that occurs in Alzheimer's disease. In this work, we show that bis-8(aminoquinoline) ligands, copper(II) specific chelators, are able to catalytically extract Cu(II) from Cu-Aβ1-16 and then completely release Cu(I) in the presence of glutathione to provide a Cu(I)-glutathione complex, a biological intermediate that is able to deliver copper to apo forms of copper-protein complexes. These data demonstrate that bis-8(aminoquinolines) can perform the transfer of copper ions from the pathological Cu-amyloid complexes to regular copper-protein complexes. These copper-specific ligands assist GSH to recycle Cu(I) in an AD brain and consequently slow down oxidative damage that is due to copper dysregulation in Alzheimer's disease. Under the same conditions, we have shown that the copper complex of PBT2, a mono(8-hydroxyquinoline) previously used as a drug candidate, does not efficiently release copper in the presence of GSH. In addition, we report that GSH itself was unable to fully abstract copper ions from Cu-β-amyloid complexes.

  7. Strong Photo-Amplification Effects in Flexible Organic Capacitors with Small Molecular Solid-State Electrolyte Layers Sandwiched between Photo-Sensitive Conjugated Polymer Nanolayers

    PubMed Central

    Lee, Hyena; Kim, Jungnam; Kim, Hwajeong; Kim, Youngkyoo

    2016-01-01

    We demonstrate strong photo-amplification effects in flexible organic capacitors which consist of small molecular solid-state electrolyte layers sandwiched between light-sensitive conjugated polymer nanolayers. The small molecular electrolyte layers were prepared from aqueous solutions of tris(8-hydroxyquinoline-5-sulfonic acid) aluminum (ALQSA3), while poly(3-hexylthiophene) (P3HT) was employed as the light-sensitive polymer nanolayer that is spin-coated on the indium-tin oxide (ITO)-coated poly(ethylene terephthalate) (PET) film substrates. The resulting capacitors feature a multilayer device structure of PET/ITO/P3HT/ALQSA3/P3HT/ITO/PET, which were mechanically robust due to good adhesion between the ALQSA3 layers and the P3HT nanolayers. Results showed that the specific capacitance was increased by ca. 3-fold when a white light was illuminated to the flexible organic multilayer capacitors. In particular, the capacity of charge storage was remarkably (ca. 250-fold) enhanced by a white light illumination in the potentiostatic charge/discharge operation, and the photo-amplification functions were well maintained even after bending for 300 times at a bending angle of 180o. PMID:26846891

  8. Evaluation of different buffered peptone water (BPW) based enrichment broths for detection of Gram-negative foodborne pathogens from various food matrices.

    PubMed

    Margot, H; Zwietering, M H; Joosten, H; O'Mahony, Emer; Stephan, R

    2015-12-01

    This study evaluated the effects of changing the composition of the pre-enrichment medium buffered peptone water (BPW) on the growth of stressed and unstressed Gram-negative foodborne pathogens in a one-broth enrichment strategy. BPW supplemented with an available iron source and sodium pyruvate, along with low levels of 8-hydroxyquinoline and sodium deoxycholate (BPW-S) improved the recovery of desiccated Cronobacter spp. from powdered infant formula. Growth of Salmonella and STEC was comparable in all BPW variants tested for different food matrices. In products with high levels of Gram-negative background flora (e.g. sprouts), the target organisms could not be reliably detected by PCR in any of the BPW variants tested unless the initial level exceeded 10(3) cfu/10 g of sprouts. Based on these results we suggest BPW-S for a one-broth enrichment strategy of stressed Gram-negative foodborne pathogens from dry products. However, a one-broth enrichment strategy based on BPW variants tested in this evaluation is not recommended for produce with a high level of Gram-negative background flora due to very high detection limits.

  9. Importance of indium tin oxide surface acido basicity for charge injection into organic materials based light emitting diodes

    NASA Astrophysics Data System (ADS)

    Nüesch, F.; Forsythe, E. W.; Le, Q. T.; Gao, Y.; Rothberg, L. J.

    2000-06-01

    The influence of the indium tin oxide (ITO) electrode surface acido basicity on organic electroluminescent device characteristics is studied. As measured by photoelectron spectroscopy, acid and base treatments produce large work function shifts of the oxide compared to standard ITO treated by an oxygen plasma or water. The current onsets for triphenyldiamine (TPD) single layer diodes sandwiched between ITO and a silver electrode are in qualitative agreement with the work function of the hole injecting oxide electrode. However, saturated photovoltage measurements on single layer diodes built on acid and water treated ITO disagree with the work function obtained from photoelectron experiments. This is explained by protonation of the diamine layer close to the electrode surface producing a charged double layer. It suggests that even acidic surface hydroxyl groups of the oxide electrode are able to protonate the diamine layer, explaining the importance of plasma cleaning to remove surface hydroxyls. The same ITO treatments are investigated in tris(8-hydroxyquinoline) (Alq) aluminum single layer diodes as well as hybrid TPD/Alq light emitting devices. Implications of metal-oxide surface acido basicity on electrode treatment and molecular material design are discussed.

  10. Determination of lithium in rocks: Fluorometric method

    USGS Publications Warehouse

    White, C.E.; Fletcher, M.H.; Parks, J.

    1951-01-01

    The gravimetric method in general use for the determination of lithium is tedious, and the final weighed product often contains other alkali metals. A fluorometric method was developed to shorten the time required for the analysis and to assure that the final determination is for lithium alone. This procedure is based on the complex formed between lithium and 8-hydroxyquinoline. The fluorescence is developed in a slightly alkaline solution of 95% alcohol and measurement is made on a photoelectric fluorometer. Separation from the ore is carried out by the wet method or by the distillation procedure. Sodium and potassium are removed by alcohol and ether, but complete separation is not necessary. Comparison of analyzed samples shows excellent agreement with spectrographic and gravimetric methods. The fluorometric method is more rapid than the gravimetric and produces more conclusive results. Another useful application is in the preparation of standard lithium solutions from reagent quality salts when a known standard is available. In this case no separations are necessary.

  11. Influence of electron transport layer thickness on optical properties of organic light-emitting diodes

    SciTech Connect

    Liu, Guohong; Liu, Yong; Li, Baojun; Zhou, Xiang

    2015-06-07

    We investigate experimentally and theoretically the influence of electron transport layer (ETL) thickness on properties of typical N,N′-diphenyl-N,N′-bis(1-naphthyl)-[1,1′-biphthyl]-4,4′-diamine (NPB)/tris-(8-hydroxyquinoline) aluminum (Alq{sub 3}) heterojunction based organic light-emitting diodes (OLEDs), where the thickness of ETL is varied to adjust the distance between the emitting zone and the metal electrode. The devices showed a maximum current efficiency of 3.8 cd/A when the ETL thickness is around 50 nm corresponding to an emitter-cathode distance of 80 nm, and a second maximum current efficiency of 2.6 cd/A when the ETL thickness is around 210 nm corresponding to an emitter-cathode distance of 240 nm. We adopt a rigorous electromagnetic approach that takes parameters, such as dipole orientation, polarization, light emitting angle, exciton recombination zone, and diffusion length into account to model the optical properties of devices as a function of varying ETL thickness. Our simulation results are accurately consistent with the experimental results with a widely varying thickness of ETL, indicating that the theoretical model may be helpful to design high efficiency OLEDs.

  12. Determination of molybdenum in plants by vortex-assisted emulsification solidified floating organic drop microextraction and flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Oviedo, Jenny A.; Fialho, Lucimar L.; Nóbrega, Joaquim A.

    2013-08-01

    A fast and sensitive procedure for extraction and preconcentration of molybdenum in plant samples based on solidified floating organic drop microextraction combined with flame atomic absorption spectrometry and discrete nebulization was developed. 8-Hydroxyquinoline (8-HQ) was used as complexing agent. The experimental conditions established were: 0.5% m v- 1 of 8-HQ, 60 μL of 1-undecanol as the extractant phase, 2 min vortex extraction time, centrifugation for 2 min at 2000 rpm, 10 min into an ice bath and discrete nebulization by introducing 200 μL of solution. The calibration curve was linear from 0.02 to 4.0 mg L- 1 with a limit of detection of 4.9 μg L- 1 and an enhancement factor of 67. The relative standard deviations for ten replicate measurements of 0.05 and 1.0 mg L- 1 Mo were 6.0 and 14.5%, respectively. The developed procedure was applied for determining molybdenum in corn samples and accuracy was proved using certified reference materials.

  13. [Increase in yeast and bacterial sensitivity to inhibitors and riboflavin as affected by high sulfate and phosphate concentrations].

    PubMed

    Sibirnyĭ, A A; Shavlovskiĭ, G M

    1981-01-01

    Cultivation of the yeast Pichia guilliermondii in a medium with a high content of sulfate or phosphate ions (0.6 M and higher) increased its susceptibility to actinomycin D and 7-methyl-8-trifluoromethyl 10-(1'-D-ribityl)isoalloxazin, and analog of riboflavin, and decreased the requirement of the riboflavin-dependent mutant P7 in exogenous vitamin B2. The protoplasts of the yeast were also very susceptible to actinomycin D when they were incubated in a medium with a high sulfate concentration. Sulfate and phosphate ions elevated the susceptibility to actinomycin D in the following yeasts, apart from P. guilliermondii: Pichia pinus, Saccharomyces cerevisiae, Torulopsis candida, hansenula polymorpha, Schwanniomyces occidentalis, Candida utilis and Candida tropicalis. The growth of Escherichia coli was also very susceptible to actinomycin D when the bacterium was cultivated in medium with an elevated phosphate concentration (0.2 M). High phosphate or sulfate concentrations can be used in experiments aimed at studying the effect of transcription inhibitors (actinomycin D, 8-hydroxyquinoline) on the induction of alpha-glucosidase in P. guilliermondii. PMID:7017354

  14. Bias-induced photoluminescence quenching of single colloidal quantum dots embedded in organic semiconductors.

    PubMed

    Huang, Hao; Dorn, August; Nair, Gautham P; Bulović, Vladimir; Bawendi, Moungi G

    2007-12-01

    We demonstrate reversible quenching of the photoluminescence from single CdSe/ZnS colloidal quantum dots embedded in thin films of the molecular organic semiconductor N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) in a layered device structure. Our analysis, based on current and charge carrier density, points toward field ionization as the dominant photoluminescence quenching mechanism. Blinking traces from individual quantum dots reveal that the photoluminescence amplitude decreases continuously as a function of increasing forward bias even at the single quantum dot level. In addition, we show that quantum dot photoluminescence is quenched by aluminum tris(8-hydroxyquinoline) (Alq3) in chloroform solutions as well as in thin solid films of Alq3 whereas TPD has little effect. This highlights the importance of chemical compatibility between semiconductor nanocrystals and surrounding organic semiconductors. Our study helps elucidate elementary interactions between quantum dots and organic semiconductors, knowledge needed for designing efficient quantum dot organic optoelectronic devices.

  15. Synthesis and investigation of antimicrobial activity and spectrophotometric and dyeing properties of some novel azo disperse dyes based on naphthalimides.

    PubMed

    Shaki, Hanieh; Gharanjig, Kamaladin; Khosravi, Alireza

    2015-01-01

    A series of novel disperse dyes containing azo group were synthesized through a diazotization and coupling process. The 4-amino-N-2-aminomethylpyridine-1,8-naphthalimide was diazotized by nitrosylsulphuric acid and coupled with various aromatic amines such as N,N-diethylaniline, N,N-dihydroxyethylaniline, 8-hydroxyquinoline, and 2-methylindole. Chemical structures of the synthesized dyes were characterized by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), proton nuclear magnetic resonance ((1) H NMR), carbon nuclear magnetic resonance ((13) C NMR), elemental analysis, and ultraviolet-visible (UV-visible) spectroscopy. The spectrophotometric data of all dyes were evaluated in various solvents with different polarity. Eventually, the dyes were applied on polyamide fabrics in order to investigate their dyeing properties. The fastness properties of the dyed fabrics such as wash, light, and rubbing fastness degrees were measured by standard methods. Moreover, the color gamut of the synthesized dyes was measured on polyamide fabrics. Results indicated that some of the synthesized dyes were able to dye polyamide fabrics with deep shades. They had very good wash and rubbing fastness degrees and moderate-to-good light fastness on polyamide fabrics. The antibacterial and antifungal activities of the synthesized dyes were evaluated in soluble state and on the dyed fabrics. The results indicated that dye 2 containing N,N-dihydroxyethylaniline as coupler had the highest activity against all the bacteria and fungi used.

  16. New resin gel for uranium determination by diffusive gradient in thin films technique.

    PubMed

    Gregusova, Michaela; Docekal, Bohumil

    2011-01-17

    A new resin gel based on Spheron-Oxin(®) chelating ion-exchanger with anchored 8-hydroxyquinoline functional groups was tested for application in diffusive gradient in thin film technique (DGT) for determination of uranium. Selectivity of uranium uptake from model carbonate loaded solutions of natural water was studied under laboratory conditions and compared with selectivity of the conventional Chelex 100 based resin gel. The affinity of Spheron-Oxin(®) functional groups enables determination of the overall uranium concentration in water containing carbonates up to the concentration level of 10(2) mg L(-1). The effect of uranium binding to the polyacrylamide (APA) and agarose diffusive gels (AGE) was also studied. Uranium is probably bound in both gels by a weak interaction with traces of acrylic acid groups in the structure of APA gel and with pyruvic and sulfonic acid groups in the AGE gel. These sorption effects can be eliminated to the negligible level by prolonged deployment of DGT probes or by disassembling probes after the 1-2 days post-sampling period that is sufficient for release of uranium from diffusive gel and its sorption in resin gel. PMID:21167996

  17. Lifetime improvement mechanism in organic light-emitting diodes with mixed materials at a heterojunction interface

    NASA Astrophysics Data System (ADS)

    Minagawa, Masahiro; Takahashi, Noriko

    2016-02-01

    To investigate the lifetime improvement mechanism caused by mixing at the heterojunction interface, organic light-emitting diodes (OLEDs) with stacked and mixed 4,4‧-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl (α-NPD)/tris(8-hydroxyquinoline)aluminum (Alq3) interfaces were fabricated, and changes in their displacement current due to continuous operation were measured. A decrease in accumulated holes at the α-NPD/Alq3 interface was observed in the stacked configuration devices over longer operations. These results indicate that the injected hole density was reduced during continuous operation, implying that the carrier balance became uneven in the emission region. However, few accumulated holes and changes in the displacement current due to continuous operation were observed in the devices having the mixed layer. Therefore, it was deduced that the number of holes concentrated between the α-NPD and Alq3 layers was decreased by mixing at the heterojunction interface, and that the change in the number of holes was smaller during continuous operation, resulting in less degradation.

  18. Direct and selective flow-injection method for the simultaneous spectrophotometric determination of calcium and magnesium in red and white wines using online dilution based on "Zone Sampling".

    PubMed

    Themelis, D G; Tzanavaras, P D; Trellopoulos, A V; Sofoniou, M C

    2001-11-01

    The present work reports a selective and simple flow injection method for the direct and simultaneous determination of calcium and magnesium ions in red, rose, and white wines. Both ions react with methylthymol blue (MTB) at a strongly basic medium to form colored complexes that are monitored spectrophotometrically (lambda(max) = 610 nm). The simultaneous determination is achieved by online masking of magnesium by 8-hydroxyquinoline (8-HQ). Incorporating an online dilution mode based on the "zone sampling" technique in the FI system, the determination of both analytes was achieved without any pretreatment of the samples, in the range 0-350 mg L(-1) and 0-200 mg L(-1) for Ca(II) and Mg(II), respectively. The 3 sigma detection limits were quite satisfactory (2.1 and 1.8 mg L(-1) for Ca(II) and Mg(II) respectively), and the precision was 1.2% (at a mixture of 100.0 mg L(-1) Ca(II) + 100.0 mg L(-1) Mg(II), n = 12). A detailed study of interferences proved that the proposed method is highly selective. The application of the method to the direct analysis of red, rose, and white wines yielded excellent results compared with those obtained by using FAAS as a reference method (e(r) < 2.8%).

  19. Cloud point extraction-flame atomic absorption spectrometry method for preconcentration and determination of trace cadmium in water samples.

    PubMed

    Ning, Jinyan; Jiao, Yang; Zhao, Jiao; Meng, Lifen; Yang, Yaling

    2014-01-01

    A method based on cloud point extraction (CPE) separation/preconcentration of trace cadmium (Cd) as a prior step to its determination by flame atomic absorption spectrometry has been developed. Cadmium reacted with 8-hydroxyquinoline to form hydrophobic chelates, which were extracted into the micelles of nonionic surfactant oligoethylene glycol monoalkyl ether (Genapol X-080) in an alkaline medium. Octanol was used to depress the cloud point of Genapol X-080 in the extraction process. The chemical variables that affect the CPE, such as pH of complexation reaction, amount of chelating agent, Genapol X-080 and octanol were evaluated and optimized. Under optimized conditions, linearity was obeyed in the range of 10-500 μg/L, with the correlation coefficient of 0.9993. For 5 mL of sample solution, the enhancement factor was about 20. The limit of detection and limit of quantification of the method were 0.21 and 0.63 μg/L, respectively. The relative standard deviations (n = 6) was 3.2% for a solution containing 100 μg/L of Cd. The accuracy of the preconcentration system was evaluated by recovery measurements on spiked water samples. Recoveries of spiked samples varied in the range of 94.1-103.8%.

  20. Determination of cadmium(II), cobalt(II), nickel(II), lead(II), zinc(II), and copper(II) in water samples using dual-cloud point extraction and inductively coupled plasma emission spectrometry.

    PubMed

    Zhao, Lingling; Zhong, Shuxian; Fang, Keming; Qian, Zhaosheng; Chen, Jianrong

    2012-11-15

    A dual-cloud point extraction (d-CPE) procedure has been developed for simultaneous pre-concentration and separation of heavy metal ions (Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ion) in water samples by inductively coupled plasma optical emission spectrometry (ICP-OES). The procedure is based on forming complexes of metal ion with 8-hydroxyquinoline (8-HQ) into the as-formed Triton X-114 surfactant rich phase. Instead of direct injection or analysis, the surfactant rich phase containing the complexes was treated by nitric acid, and the detected ions were back extracted again into aqueous phase at the second cloud point extraction stage, and finally determined by ICP-OES. Under the optimum conditions (pH=7.0, Triton X-114=0.05% (w/v), 8-HQ=2.0×10(-4) mol L(-1), HNO3=0.8 mol L(-1)), the detection limits for Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ions were 0.01, 0.04, 0.01, 0.34, 0.05, and 0.04 μg L(-1), respectively. Relative standard deviation (RSD) values for 10 replicates at 100 μg L(-1) were lower than 6.0%. The proposed method could be successfully applied to the determination of Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ion in water samples.

  1. Improvement of the cloud point extraction of uranyl ions by the addition of ionic liquids.

    PubMed

    Gao, Song; Sun, Taoxiang; Chen, Qingde; Shen, Xinghai

    2013-12-15

    The cloud point extraction (CPE) of uranyl ions by different kinds of extractants in Triton X-114 (TX-114) micellar solution was investigated upon the addition of ionic liquids (ILs) with various anions, i.e., bromide (Br(-)), tetrafluoroborate (BF4(-)), hexafluorophosphate (PF6(-)) and bis[(trifluoromethyl)sulfonyl]imide (NTf2(-)). A significant increase of the extraction efficiency was found on the addition of NTf2(-) based ILs when using neutral extractant tri-octylphosphine oxide (TOPO), and the extraction efficiency kept high at both nearly neutral and high acidity. However, the CPE with acidic extractants, e.g., bis(2-ethylhexyl) phosphoric acid (HDEHP) and 8-hydroxyquinoline (8-HQ) which are only effective at nearly neutral condition, was not improved by ILs. The results of zeta potential and (19)F NMR measurements indicated that the anion NTf2(-) penetrated into the TX-114 micelles and was enriched in the surfactant-rich phase during the CPE process. Meanwhile, NTf2(-) may act as a counterion in the CPE of UO2(2+) by TOPO. Furthermore, the addition of IL increased the separation factor of UO2(2+) and La(3+), which implied that in the micelle TOPO, NTf2(-) and NO3(-) established a soft template for UO2(2+). Therefore, the combination of CPE and IL provided a supramolecular recognition to concentrate UO2(2+) efficiently and selectively.

  2. A Green Preconcentration Method for Determination of Cobalt and Lead in Fresh Surface and Waste Water Samples Prior to Flame Atomic Absorption Spectrometry

    PubMed Central

    Naeemullah; Kazi, Tasneem Gul; Shah, Faheem; Afridi, Hassan Imran; Khan, Sumaira; Arian, Sadaf Sadia; Brahman, Kapil Dev

    2012-01-01

    Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead (Pb) in fresh and wastewater samples. The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant. Experiments were conducted to assess the effect of different chemical variables such as pH, amounts of reagents (oxine and Triton X-114), temperature, incubation time, and sample volume. After phase separation, based on the cloud point, the surfactant-rich phase was diluted with acidic ethanol prior to its analysis by the flame atomic absorption spectrometry (FAAS). The enhancement factors 70 and 50 with detection limits of 0.26 μg L−1 and 0.44 μg L−1 were obtained for Co and Pb, respectively. In order to validate the developed method, a certified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with the certified values. The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and waste water sample. PMID:23227429

  3. Adhesion of Entamoeba histolytica trophozoites to human erythrocytes.

    PubMed Central

    López-Revilla, R; Cano-Mancera, R

    1982-01-01

    To understand the mechanism of Entamoeba histolytica adhesion, we characterized the binding of trophozoites to human erythrocytes (RBC) in suspension by measuring the kinetics of amoeba-RBC complex formation. Adhesion was very efficient, since most of the amoebae were complexed with RBC after only 5 min at 37 degrees C in mixtures containing 10(4) amoebae and 10(6) RBC per ml; the adhesion rate depended on amoeba and RBC concentrations, but not on the A, B, and O human blood groups, and was maximal at 37 degrees C and pH 7.3 in the presence of 4 mM Ca2+ and 1 mM Mg2+. Adhesion was prevented if trophozoites were fixed with glutaraldehyde, but only decreased slightly if RBC were previously fixed; it decreased in the absence of glucose and was inhibited as a function of the concentration of cytochalasin B and of the metabolic inhibitors bathophenanthroline and 8-hydroxyquinoline. From these results we conclude that E. histolytica adhesion is an active process that depends on the amoebal cytoskeleton and metabolic energy and on the mobility of both amoebal and RBC surface ligands. Images PMID:6286491

  4. Strong Photo-Amplification Effects in Flexible Organic Capacitors with Small Molecular Solid-State Electrolyte Layers Sandwiched between Photo-Sensitive Conjugated Polymer Nanolayers

    NASA Astrophysics Data System (ADS)

    Lee, Hyena; Kim, Jungnam; Kim, Hwajeong; Kim, Youngkyoo

    2016-02-01

    We demonstrate strong photo-amplification effects in flexible organic capacitors which consist of small molecular solid-state electrolyte layers sandwiched between light-sensitive conjugated polymer nanolayers. The small molecular electrolyte layers were prepared from aqueous solutions of tris(8-hydroxyquinoline-5-sulfonic acid) aluminum (ALQSA3), while poly(3-hexylthiophene) (P3HT) was employed as the light-sensitive polymer nanolayer that is spin-coated on the indium-tin oxide (ITO)-coated poly(ethylene terephthalate) (PET) film substrates. The resulting capacitors feature a multilayer device structure of PET/ITO/P3HT/ALQSA3/P3HT/ITO/PET, which were mechanically robust due to good adhesion between the ALQSA3 layers and the P3HT nanolayers. Results showed that the specific capacitance was increased by ca. 3-fold when a white light was illuminated to the flexible organic multilayer capacitors. In particular, the capacity of charge storage was remarkably (ca. 250-fold) enhanced by a white light illumination in the potentiostatic charge/discharge operation, and the photo-amplification functions were well maintained even after bending for 300 times at a bending angle of 180o.

  5. Synthesis and investigation of antimicrobial activity and spectrophotometric and dyeing properties of some novel azo disperse dyes based on naphthalimides.

    PubMed

    Shaki, Hanieh; Gharanjig, Kamaladin; Khosravi, Alireza

    2015-01-01

    A series of novel disperse dyes containing azo group were synthesized through a diazotization and coupling process. The 4-amino-N-2-aminomethylpyridine-1,8-naphthalimide was diazotized by nitrosylsulphuric acid and coupled with various aromatic amines such as N,N-diethylaniline, N,N-dihydroxyethylaniline, 8-hydroxyquinoline, and 2-methylindole. Chemical structures of the synthesized dyes were characterized by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), proton nuclear magnetic resonance ((1) H NMR), carbon nuclear magnetic resonance ((13) C NMR), elemental analysis, and ultraviolet-visible (UV-visible) spectroscopy. The spectrophotometric data of all dyes were evaluated in various solvents with different polarity. Eventually, the dyes were applied on polyamide fabrics in order to investigate their dyeing properties. The fastness properties of the dyed fabrics such as wash, light, and rubbing fastness degrees were measured by standard methods. Moreover, the color gamut of the synthesized dyes was measured on polyamide fabrics. Results indicated that some of the synthesized dyes were able to dye polyamide fabrics with deep shades. They had very good wash and rubbing fastness degrees and moderate-to-good light fastness on polyamide fabrics. The antibacterial and antifungal activities of the synthesized dyes were evaluated in soluble state and on the dyed fabrics. The results indicated that dye 2 containing N,N-dihydroxyethylaniline as coupler had the highest activity against all the bacteria and fungi used. PMID:25967675

  6. PET neuroimaging studies of [18F]CABS13 in a double transgenic mouse model of Alzheimer’s disease and non-human primates

    PubMed Central

    Liang, Steven H.; Holland, Jason P.; Stephenson, Nickeisha A.; Kassenbrock, Alina; Rotstein, Benjamin H.; Daignault, Cory P.; Lewis, Rebecca; Collier, Lee; Hooker, Jacob M.; Vasdev, Neil

    2016-01-01

    Fluorine-18 labeled 2-fluoro-8-hydroxyquinoline ([18F]CABS13) is a promising positron emission tomography (PET) radiopharmaceutical based on a metal chelator developed to probe the “metal hypothesis of Alzheimer’s disease”. Herein, a practical radiosynthesis of [18F]CABS13 was achieved by radiofluorination followed by deprotection of an O-benzyloxymethyl group. Automated production and formulation of [18F]CABS13 resulted in 19 ± 5% uncorrected radiochemical yield, relative to starting [18F]fluoride, with ≥95% chemical and radiochemical purities, and high specific activity (>2.5 Ci/μmol) within 80 minutes. Temporal PET neuroimaging studies were carried out in female transgenic B6C3- Tg(APPswe,PSEN1dE9)85Dbo/J (APP/PS1) and age-matched wild-type (WT) B6C3F1/J control mice at 3, 7 and 10 months of age. [18F]CABS13 showed an overall higher uptake and retention of radioactivity in the central nervous system of APP/PS1 mice versus WT mice with increasing age. However, PET/magnetic resonance imaging in normal non-human primates revealed that the tracer had low uptake in the brain and rapid formation of a hydrophilic radiometabolite. Identification of more metabolically stable 18F-hydroxyquinolines that can be readily accessed by the radiochemical strategy presented herein is underway. PMID:25776827

  7. Iron Chelators and Antioxidants Regenerate Neuritic Tree and Nigrostriatal Fibers of MPP+/MPTP-Lesioned Dopaminergic Neurons

    PubMed Central

    Aguirre, Pabla; Mena, Natalia P.; Carrasco, Carlos M.; Muñoz, Yorka; Pérez-Henríquez, Patricio; Morales, Rodrigo A.; Cassels, Bruce K.; Méndez-Gálvez, Carolina; García-Beltrán, Olimpo; González-Billault, Christian; Núñez, Marco T.

    2015-01-01

    Neuronal death in Parkinson’s disease (PD) is often preceded by axodendritic tree retraction and loss of neuronal functionality. The presence of non-functional but live neurons opens therapeutic possibilities to recover functionality before clinical symptoms develop. Considering that iron accumulation and oxidative damage are conditions commonly found in PD, we tested the possible neuritogenic effects of iron chelators and antioxidant agents. We used three commercial chelators: DFO, deferiprone and 2.2’-dypyridyl, and three 8-hydroxyquinoline-based iron chelators: M30, 7MH and 7DH, and we evaluated their effects in vitro using a mesencephalic cell culture treated with the Parkinsonian toxin MPP+ and in vivo using the MPTP mouse model. All chelators tested promoted the emergence of new tyrosine hydroxylase (TH)-positive processes, increased axodendritic tree length and protected cells against lipoperoxidation. Chelator treatment resulted in the generation of processes containing the presynaptic marker synaptophysin. The antioxidants N-acetylcysteine and dymetylthiourea also enhanced axodendritic tree recovery in vitro, an indication that reducing oxidative tone fosters neuritogenesis in MPP+-damaged neurons. Oral administration to mice of the M30 chelator for 14 days after MPTP treatment resulted in increased TH- and GIRK2-positive nigra cells and nigrostriatal fibers. Our results support a role for oral iron chelators as good candidates for the early treatment of PD, at stages of the disease where there is axodendritic tree retraction without neuronal death. PMID:26658949

  8. Comparative study of dielectric functions of complex organic heterostructures

    NASA Astrophysics Data System (ADS)

    Gordan, O. D.; Hermann, S.; Friedrich, M.; Zahn, D. R. T.

    2005-11-01

    Organic/organic heterostructures and mixed layers were prepared by organic molecular beam deposition (OMBD) in high vacuum (HV) on hydrogen passivated (111) oriented silicon. The substrates were kept at room temperature during the deposition. The organic superstructures consisting in alternative layers of tris-(8-hydroxyquinoline)-aluminum(III) (Alq3)/N,N-Di-[(1-naphthyl)-N,N-diphenyl]-(1,1-biphenyl)-4,4-diamine (-NPD) and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA)/copper phthalocyanine (CuPc) were investigated by means of spectroscopic ellipsometry in the 0.73-5 eV spectral range. Additionally reflection infra-red (IR) measurements were performed using p- and s-polarisation.Taking into account the dielectric function of the single layers the optical response of the Alq3/-NPD superstructure can be modeled assuming sharp interfaces. However, for the PTCDA/CuPc superstructure the optical response requires a more sophisticated approach than simply superimposing the responses of the individual layers. The deviation between simulated and experimental data is assigned to the molecular interaction at the interfaces between PTCDA and CuPc. This can affect the molecular orientation and the optical properties.

  9. Iron Chelators and Antioxidants Regenerate Neuritic Tree and Nigrostriatal Fibers of MPP+/MPTP-Lesioned Dopaminergic Neurons.

    PubMed

    Aguirre, Pabla; Mena, Natalia P; Carrasco, Carlos M; Muñoz, Yorka; Pérez-Henríquez, Patricio; Morales, Rodrigo A; Cassels, Bruce K; Méndez-Gálvez, Carolina; García-Beltrán, Olimpo; González-Billault, Christian; Núñez, Marco T

    2015-01-01

    Neuronal death in Parkinson's disease (PD) is often preceded by axodendritic tree retraction and loss of neuronal functionality. The presence of non-functional but live neurons opens therapeutic possibilities to recover functionality before clinical symptoms develop. Considering that iron accumulation and oxidative damage are conditions commonly found in PD, we tested the possible neuritogenic effects of iron chelators and antioxidant agents. We used three commercial chelators: DFO, deferiprone and 2.2'-dypyridyl, and three 8-hydroxyquinoline-based iron chelators: M30, 7MH and 7DH, and we evaluated their effects in vitro using a mesencephalic cell culture treated with the Parkinsonian toxin MPP+ and in vivo using the MPTP mouse model. All chelators tested promoted the emergence of new tyrosine hydroxylase (TH)-positive processes, increased axodendritic tree length and protected cells against lipoperoxidation. Chelator treatment resulted in the generation of processes containing the presynaptic marker synaptophysin. The antioxidants N-acetylcysteine and dymetylthiourea also enhanced axodendritic tree recovery in vitro, an indication that reducing oxidative tone fosters neuritogenesis in MPP+-damaged neurons. Oral administration to mice of the M30 chelator for 14 days after MPTP treatment resulted in increased TH- and GIRK2-positive nigra cells and nigrostriatal fibers. Our results support a role for oral iron chelators as good candidates for the early treatment of PD, at stages of the disease where there is axodendritic tree retraction without neuronal death. PMID:26658949

  10. White organic light-emitting diodes based on tandem structures

    NASA Astrophysics Data System (ADS)

    Guo, Fawen; Ma, Dongge

    2005-10-01

    White organic light-emitting diodes made of two electroluminescent (EL) units connected by a charge generation layer were fabricated. Thus, with a tandem structure of indium tin oxide/N ,N'-di(naphthalene-1-yl)-N ,N'-diphenyl-benzidine (NPB)/9,10-bis-(β-naphthyl)-anthrene (ADN)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/tris(8-hydroxyquinoline) aluminum (Alq3)/BCP:Li/V2O5/NPB/Alq3:4-(dicyanomethylene)-2-t-butyle-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)4H-pyran (DCJTB)/Alq3/LiF/Al, a stable white light with Commission Internationale De L'Eclairage chromaticity coordinates from (0.35, 0.32) at 18V to (0.36, 0.36) at 50V was generated. It was clearly seen that the EL spectra consist of red band at 600nm due to DCJTB, green band at 505nm due to Alq3, and blue band at 435nm due to ADN, and the current efficiency and brightness equal basically to the sum of the two EL units. As a result, the tandem devices showed white light emission with a maximum brightness of 10200cd /m2 at a bias of 40V and a maximum current efficiency of 10.7cd/A at a current density of 3.5mA/cm2.

  11. Vortex-assisted ionic liquid microextraction coupled to flame atomic absorption spectrometry for determination of trace levels of cadmium in real samples

    PubMed Central

    Chamsaz, Mahmoud; Atarodi, Atefe; Eftekhari, Mohammad; Asadpour, Saeid; Adibi, Mina

    2012-01-01

    A simple and rapid vortex assisted ionic liquid based liquid–liquid microextraction technique (VALLME) was proposed for preconcentration of trace levels of cadmium. According to this method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Cadmium preconcentration was mediated by chelation with the 8-hydroxyquinoline (oxine) reagent and an IL, 1-octyl-3-methylimidazolium hexafluorophosphate ([Omim][PF6]) was chosen as the extraction solvent to extract the hydrophobic complex. Several variables such as sample pH, concentration of oxine, volume of [Omim][PF6] and extraction time were investigated in details and optimum conditions were selected. Under the optimum conditions, the limit of detection (LOD) was 2.9 μg L−1 for Cd (ІІ) and relative standard deviation (RSD%) for five replicate determinations of 125 μg L−1 was 4.1%. The method was successfully applied to the determination of cadmium in tap water, apple and rice samples. PMID:25685399

  12. Electrochemical spectroscopic investigations on the interaction of an ytterbium complex with DNA and their analytical applications such as biosensor.

    PubMed

    Ilkhani, Hoda; Ganjali, Mohamad Reza; Arvand, Majid; Hejazi, Mohammad Saeid; Azimi, Fateme; Norouzi, Parviz

    2011-12-01

    Metal ion-DNA interactions are important in nature, often changing the genetic material's structure and function. A new Yb complex of YbCl(3) (tris(8-hydroxyquinoline-5-sulfonic acid) ytterbium) was synthesized and utilized as an electrochemical indicator for the detection of DNA oligonucleotide based on its interaction with Yb(QS)(3). Cyclic voltammetry (CV) and fluorescence spectroscopy were used to investigate the interaction of Yb(QS)(3) with ds-DNA. It was revealed that Yb(QS)(3) presented an excellent electrochemical activity on glassy carbon electrode (GCE) and could intercalate into the double helix of double-stranded DNA (ds-DNA). The binding mechanism of interaction was elucidated on glassy carbon electrode dipped in DNA solution and DNA modified carbon paste electrode by using differential pulse voltammetry and cyclic voltammetry. The binding ratio between this complex and ds-DNA was calculated to be 1:1. The extent of hybridization was evaluated on the basis of the difference between signals of Yb(QS)(3) with probe DNA before and after hybridization with complementary DNA. With this approach, this DNA could be quantified over the range from 1 × 10(-8) to 1.1 × 10(-7)M. The interaction mode between Yb(QS)(3) and DNA was found to be mainly intercalative interaction. These results were confirmed with fluorescence experiments.

  13. Monolayer Phases of a Dipolar Perylene Derivative on Au(111) and Surface Potential Build-Up in Multilayers.

    PubMed

    Niederhausen, Jens; Kersell, Heath R; Christodoulou, Christos; Heimel, Georg; Wonneberger, Henrike; Müllen, Klaus; Rabe, Jürgen P; Hla, Saw-Wai; Koch, Norbert

    2016-04-19

    9-(Bis-p-tert-octylphenyl)-amino-perylene-3,4-dicarboxy anhydride (BOPA-PDCA) is a strongly dipolar molecule representing a group of asymmetrically substituted perylenes that are employed in dye-sensitized solar cells and hold great promise for discotic liquid crystal applications. Thin BOPA-PDCA films with orientated dipole moments can potentially be used to tune the energy-level alignment in electronic devices and store information. To help assessing these prospects, we here elucidate the molecular self-assembly and electronic structure of BOPA-PCDA employing room temperature scanning tunneling microscopy and spectroscopy in combination with ultraviolet and X-ray photoelectron spectroscopies. BOPA-PCDA monolayers on Au(111) exclusively form in-plane antiferroelectric phases. The molecular arrangements, the increase of the average number of molecules per unit cell via ripening, and the rearrangement upon manipulation with the STM tip indicate an influence of the dipole moment on the molecular assembly and the rearrangement. A slightly preferred out-of-plane orientation of the molecules in the multilayer induces a surface potential of 1.2 eV. This resembles the giant surface potential effect that was reported for vacuum-deposited tris(8-hydroxyquinoline)aluminum and deemed applicable for data storage. Notably, the surface potential in the case of BOPA-PDCA can in part be reversibly removed by visible light irradiation. PMID:26991048

  14. Preparation of gallium-68 radiopharmaceuticals for positron tomography. Progress report, November 1, 1977-October 31, 1980

    SciTech Connect

    Welch, M.J.

    1980-06-01

    Although the germanium-68 ..-->.. gallium-68 generator is probably the only source of positron-emitting radionuclides that could enable the widespread application of positron tomography, the commercially available /sup 68/Ga//sup 68/Ge generator system suffers from several major disadvantages. The most important of these is that the generator is eluted with EDTA, which forms a very strong chelate with gallium. In order to produce radiopharmaceuticals other than /sup 68/Ga-EDTA, it is first necessary to break the stable EDTA complex and remove all traces of EDTA. This procedure adds several steps and a significant amount of time to procedures for preparing /sup 68/Ga-radiopharmaceuticals. We have developed a new generator using a solvent extraction system which will produce /sup 68/Ga-oxine (8-hydroxyquinoline), a weak chelate. Using this agent we have synthesized several /sup 68/Ga-radiopharmaceuticals and tested them in vitro and in vivo. We have also carried out some preliminary studies to compare generator systems which produce /sup 68/Ga in an ionic form. Attempts have been made using polarographic and chromatographic techniques, and in vivo distribution data to investigate the stability of radiogallium complexes with a series of potentially lipophilic complexing agents.

  15. Mono- and binuclear copper(II) complexes of new hydrazone ligands derived from 4,6-diacetylresorcinol: Synthesis, spectral studies and antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Shebl, Magdy; El-ghamry, Mosad A.; Khalil, Saied M. E.; Kishk, Mona A. A.

    Two new hydrazone ligands, H2L1 and H2L2, were synthesized by the condensation of 4,6-diacetylresorcinol with 3-hydrazino-5,6-diphenyl-1,2,4-triazine and isatin monohydrazone, respectively. The structures of the ligands were elucidated by elemental analyses, IR, 1H NMR, electronic and mass spectra. Reactions of the ligands with several copper(II) salts, including AcO-, NO3-, SO42-, Cl- and Br- afforded mono- and binuclear metal complexes. Also, the ligands were allowed to react with Cu(II) ion in the presence of a secondary ligand (L‧) [N,O-donor; 8-hydroxyquinoline, N,N-donor; 1,10-phenanthroline or O,O-donor; benzoylacetone]. Characterization and structure elucidation of the prepared complexes were achieved by elemental and thermal analyses, IR, electronic, mass and ESR spectra as well as conductivity and magnetic susceptibility measurements. The ESR spin Hamiltonian parameters of some complexes were calculated. The spectroscopic data showed that the H2L1 ligand acts as a neutral or monobasic tridentate ligand while the H2L2 ligand acts as a bis(monobasic tridentate) ligand. The coordination sites with the copper(II) ion are phenolic oxygen, azomethine nitrogen and triazinic nitrogen (H2L1 ligand) or isatinic oxygen (H2L2 ligand). The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. The ligands and some metal complexes showed antimicrobial activity.

  16. A retrievable and highly selective fluorescent probe for monitoring sulfide and imaging in living cells.

    PubMed

    Hou, Fengping; Huang, Liang; Xi, Pinxian; Cheng, Ju; Zhao, Xuefei; Xie, Guoqiang; Shi, Yanjun; Cheng, Fengjuan; Yao, Xiaojun; Bai, Decheng; Zeng, Zhengzhi

    2012-02-20

    A novel selective fluorescent chemosensor based on an 8-hydroxyquinoline-appended fluorescein derivative (L1) was synthesized and characterized. Once combined with Cu(2+), it displayed high specificity for sulfide anion. Among the various anions, only sulfide anion induced the revival of fluoresecence of L1, which was quenched by Cu(2+), resulting in "off-on"-type sensing of sulfide anion. What's more, the sensor was retrievable to indicate sulfide anions with Cu(2+), and S(2-), in turn, increased. With the addition of Cu(2+), compound L1 could give rise to a visible pink-to-yellow color change and green fluorescence quenching. The resulting yellow solution could change to pink and regenerate to green fluorescence immediately upon the addition of sulfide anion; however, no changes were observed in the presence of other anions, including CN(-), P(2)O(7)(4-), and other forms of sulfate, making compound L1 an extremely selective and efficient sulfide chemosensor. The signal transduction occurs via reversible formation-separation of complex L1Cu and CuS. What's more, the biological imaging study has demonstrated that the chemosensor can detect sulfur anions in biological systems at a relatively low concentration. PMID:22303885

  17. Six Zn(II) and Cd(II) coordination polymers assembled from a similar binuclear building unit: tunable structures and luminescence properties.

    PubMed

    Zhang, Liyan; Rong, Lulu; Hu, Guoli; Jin, Suo; Jia, Wei-Guo; Liu, Ji; Yuan, Guozan

    2015-04-21

    Six Zn(ii) and Cd(ii) coordination polymers were constructed by treating a 2-substituted 8-hydroxyquinolinate ligand containing a pyridyl group with zinc or cadmium salts, and characterized by a variety of techniques. Interestingly, based on a similar binuclear Zn(ii) or Cd(ii) building unit, the supramolecular structures of the six coordination polymers () exhibit an unprecedented structural diversification due to the different choices of metal salts. and represent a novel 2D framework containing 1D infinite right- and left-handed helical chains. and are 2D coordination frameworks based on binuclear Cd(ii) building units. For and , the L ligands can bridge binuclear building units forming a 1D infinite chain. Interestingly, the adjacent Cd2O2 planes of the 1D chain in are in parallel with each other, while the dihedral angle between the two Zn2O2 planes in is 83.43°. Photoluminescence properties revealed that the six coordination polymers exhibit redshifted emission maximum compared with the free ligand HL, which can be ascribed to an increased conformational rigidity and the fabrication of coplanar binuclear building units M2L2 in . Coordination polymers also display distinct fluorescence lifetimes and quantum yields because of their different metal centers and supramolecular structures.

  18. Strong Photo-Amplification Effects in Flexible Organic Capacitors with Small Molecular Solid-State Electrolyte Layers Sandwiched between Photo-Sensitive Conjugated Polymer Nanolayers.

    PubMed

    Lee, Hyena; Kim, Jungnam; Kim, Hwajeong; Kim, Youngkyoo

    2016-02-05

    We demonstrate strong photo-amplification effects in flexible organic capacitors which consist of small molecular solid-state electrolyte layers sandwiched between light-sensitive conjugated polymer nanolayers. The small molecular electrolyte layers were prepared from aqueous solutions of tris(8-hydroxyquinoline-5-sulfonic acid) aluminum (ALQSA3), while poly(3-hexylthiophene) (P3HT) was employed as the light-sensitive polymer nanolayer that is spin-coated on the indium-tin oxide (ITO)-coated poly(ethylene terephthalate) (PET) film substrates. The resulting capacitors feature a multilayer device structure of PET/ITO/P3HT/ALQSA3/P3HT/ITO/PET, which were mechanically robust due to good adhesion between the ALQSA3 layers and the P3HT nanolayers. Results showed that the specific capacitance was increased by ca. 3-fold when a white light was illuminated to the flexible organic multilayer capacitors. In particular, the capacity of charge storage was remarkably (ca. 250-fold) enhanced by a white light illumination in the potentiostatic charge/discharge operation, and the photo-amplification functions were well maintained even after bending for 300 times at a bending angle of 180(°).

  19. A green preconcentration method for determination of cobalt and lead in fresh surface and waste water samples prior to flame atomic absorption spectrometry.

    PubMed

    Naeemullah; Kazi, Tasneem Gul; Shah, Faheem; Afridi, Hassan Imran; Khan, Sumaira; Arian, Sadaf Sadia; Brahman, Kapil Dev

    2012-01-01

    Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead (Pb) in fresh and wastewater samples. The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant. Experiments were conducted to assess the effect of different chemical variables such as pH, amounts of reagents (oxine and Triton X-114), temperature, incubation time, and sample volume. After phase separation, based on the cloud point, the surfactant-rich phase was diluted with acidic ethanol prior to its analysis by the flame atomic absorption spectrometry (FAAS). The enhancement factors 70 and 50 with detection limits of 0.26 μg L(-1) and 0.44 μg L(-1) were obtained for Co and Pb, respectively. In order to validate the developed method, a certified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with the certified values. The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and waste water sample. PMID:23227429

  20. Biofunctional constituent isolated from Citrullus colocynthis fruits and structure-activity relationships of its analogues show acaricidal and insecticidal efficacy.

    PubMed

    Jeon, Ju-Hyun; Lee, Hoi-Seon

    2014-08-27

    The acaricidal and insecticidal potential of the active constituent isolated from Citrullus colocynthis fruits and its structurally related analogues was evaluated by performing leaf disk, contact toxicity, and fumigant toxicity bioassays against Tetranychus urticae, Sitophilus oryzae, and Sitophilus zeamais adults. The active constituent of C. colocynthis fruits was isolated by chromatographic techniques and was identified as 4-methylquinoline on the basis of spectroscopic analyses. To investigate the structure-activity relationships, 4-methylquinoline and its structural analogues were tested against mites and two insect pests. On the basis of the LC50 values, 7,8-benzoquinoline was the most effective against T. urticae. Quinoline, 8-hydroxyquinoline, 2-methylquinoline, 4-methylquinoline, 6-methylquinoline, 8-methylquinoline, and 7,8-benzoquinoline showed high insecticidal activities against S. oryzae and S. zeamais regardless of the application method. These results indicate that introduction of a functional group into the quinoline skeleton and changing the position of the group have an important influence on the acaricidal and insecticidal activities. Furthermore, 4-methylquinoline isolated from C. colocynthis fruits, along with its structural analogues, could be effective natural pesticides for managing spider mites and stored grain weevils. PMID:25110971

  1. Spin-dependent transport behavior in C{sub 60} and Alq{sub 3} based spin valves with a magnetite electrode (invited)

    SciTech Connect

    Zhang, Xianmin Mizukami, Shigemi; Ma, Qinli; Kubota, Takahide; Miyazaki, Terunobu; Oogane, Mikihiko; Naganuma, Hiroshi; Ando, Yasuo

    2014-05-07

    The spin-dependent transport behavior in organic semiconductors (OSs) is generally observed at low temperatures, which likely results from poor spin injection efficiency at room temperature from the ferromagnetic metal electrodes to the OS layer. Possible reasons for this are the low Curie temperature and/or the small spin polarization efficiency for the ferromagnetic electrodes used in these devices. Magnetite has potential as an advanced candidate for use as the electrode in spintronic devices, because it can achieve 100% spin polarization efficiency in theory, and has a high Curie temperature (850 K). Here, we fabricated two types of organic spin valves using magnetite as a high efficiency electrode. C{sub 60} and 8-hydroxyquinoline aluminum (Alq{sub 3}) were employed as the OS layers. Magnetoresistance ratios of around 8% and over 6% were obtained in C{sub 60} and Alq{sub 3}-based spin valves at room temperature, respectively, which are two of the highest magnetoresistance ratios in organic spin valves reported thus far. The magnetoresistance effect was systemically investigated by varying the thickness of the Alq{sub 3} layer. Moreover, the temperature dependence of the magnetoresistance ratios for C{sub 60} and Alq{sub 3}-based spin valves were evaluated to gain insight into the spin-dependent transport behavior. This study provides a useful method in designing organic spin devices operated at room temperature.

  2. Organic semiconductor/gold interface interactions: from physisorption on planar surfaces to chemical reactions with metal nanoparticles.

    PubMed

    Ligorio, Giovanni; Nardi, Marco Vittorio; Christodoulou, Christos; Koch, Norbert

    2015-08-24

    The interaction of gold nanoparticles (AuNPs) with prototypical organic semiconductors used in optoelectronics, namely, tris(8-hydroxyquinoline)aluminium (Alq3 ) and 4,4-bis[N-(1-naphthyl)-N-phenylamino]diphenyl (α-NPD), is investigated in situ by X-ray photoelectron spectroscopy (XPS). These AuNPs-on-molecule experiments are compared with the reversed molecule-on-Au cases. The molecules-on-Au systems show only weak interactions, and the evolution of the XP spectra is dominated by final-state effects. In contrast, in the AuNPs-on-molecules cases, both initial-state effects and final-state effects occur. Spectral features arising for both molecules and metal indicate charge transfer and the formation of organometallic complexes (initial-state effects). The energy shift in the metal emission underlines the size-induced nanometric nature of the molecule/Au interaction (final-state effects). Consequently, the chemical interaction between metals and organic semiconductors likely depends strongly on the deposition sequence in general.

  3. Efficient Biomimetic Hydroxylation Catalysis with a Bis(pyrazolyl)imidazolylmethane Copper Peroxide Complex.

    PubMed

    Wilfer, Claudia; Liebhäuser, Patricia; Hoffmann, Alexander; Erdmann, Hannes; Grossmann, Oleg; Runtsch, Leander; Paffenholz, Eva; Schepper, Rahel; Dick, Regina; Bauer, Matthias; Dürr, Maximilian; Ivanović-Burmazović, Ivana; Herres-Pawlis, Sonja

    2015-12-01

    Bis(pyrazolyl)methane ligands are excellent components of model complexes used to investigate the activity of the enzyme tyrosinase. Combining the N donors 3-tert-butylpyrazole and 1-methylimidazole results in a ligand that is capable of stabilising a (μ-η(2) :η(2) )-dicopper(II) core that resembles the active centre of tyrosinase. UV/Vis spectroscopy shows blueshifted UV bands in comparison to other known peroxo complexes, due to donor competition from different ligand substituents. This effect was investigated with the help of theoretical calculations, including DFT and natural transition orbital analysis. The peroxo complex acts as a catalyst capable of hydroxylating a variety of phenols by using oxygen. Catalytic conversion with the non-biological phenolic substrate 8-hydroxyquinoline resulted in remarkable turnover numbers. In stoichiometric reactions, substrate-binding kinetics was observed and the intrinsic hydroxylation constant, kox , was determined for five phenolates. It was found to be the fastest hydroxylation model system determined so far, reaching almost biological activity. Furthermore, Hammett analysis proved the electrophilic character of the reaction. This sheds light on the subtle role of donor strength and its influence on hydroxylation activity. PMID:26458073

  4. Chelating polymeric beads as potential therapeutics for Wilson's disease.

    PubMed

    Mattová, Jana; Poučková, Pavla; Kučka, Jan; Skodová, Michaela; Vetrík, Miroslav; Stěpánek, Petr; Urbánek, Petr; Petřík, Miloš; Nový, Zbyněk; Hrubý, Martin

    2014-10-01

    Wilson's disease is a genetic disorder caused by a malfunction of ATPase 7B that leads to high accumulation of copper in the organism and consequent toxic effects. We propose a gentle therapy to eliminate the excessive copper content with oral administration of insoluble non-resorbable polymer sorbents containing selective chelating groups for copper(II). Polymeric beads with the chelating agents triethylenetetramine, N,N-di(2-pyridylmethyl)amine, and 8-hydroxyquinoline (8HQB) were investigated. In a preliminary copper uptake experiment, we found that 8HQB significantly reduced copper uptake (using copper-64 as a radiotracer) after oral administration in Wistar rats. Furthermore, we measured organ radioactivity in rats to demonstrate that 8HQB radiolabelled with iodine-125 is not absorbed from the gastrointestinal tract after oral administration. Non-resorbability and the blockade of copper uptake were also confirmed with small animal imaging (PET/CT) in mice. In a long-term experiment with Wistar rats fed a diet containing the polymers, we have found that there were no signs of polymer toxicity and the addition of polymers to the diet led to a significant reduction in the copper contents in the kidneys, brains, and livers of the rats. We have shown that polymers containing specific ligands could potentially be novel therapeutics for Wilson's disease.

  5. Studies on quality and vase life of cut Gerbera jamesonii cv. 'Balance' flowers by silver nanoparticles and chlorophenol.

    PubMed

    Safa, Zakieh; Hashemabadi, Davood; Kaviani, Behzad; Nikchi, Narges; Zarchini, Mohammad

    2015-03-01

    Cut gerbera flowers are sensitive to microbial contamination and have a short vase life. Silver nanoparticles are used in various applications as an antimicrobial agent. An experiment was conducted to determine the effect of different concentrations of SNP and chlorophenol to extend the vase life and postharvest quality of gerbera (Gerberajamesonii cv. 'Balance') cut flowers. Cut gerbera flowers were kept in solutions containing 0, 5, 10 and 20 mg l(-1) SNP and/or 0, 5 and 10 mM chlorophenol for 24 hr; then held in vase solution containing 250 mg l(-1) 8-hydroxyquinoline sulphate and 3% sucrose. The maximum vase life (16.33 days) was observed in flowers held in solution containing 10 mg l(-1) SNP. The 5 mg l(-1) SNP plus 10 mM chlorophenol and 10 mg l(-1) SNP plus 5 mM chlorophenol inhibited bacterial growth in the vase solution. The minimum fresh weight loss (6.48 gr) during the vase period was observed for flowers kept in solution containing 20 mg l(-1)1 SNP. The results revealed that SNP and chlorophenol have the potential to extend vase life and enhanc the postharvest quality of cut gerbera cv. 'Balance' flowers.

  6. Bovine liver dihydropyrimidine amidohydrolase: pH dependencies of inactivation by chelators and steady-state kinetic properties.

    PubMed

    Lee, M H; Cowling, R A; Sander, E G; Pettigrew, D W

    1986-07-01

    Dihydropyrimidine amidohydrolase (EC 3.5.2.2) catalyzes the reversible hydrolysis of 5,6-dihydropyrimidines to the corresponding beta-ureido acids. Previous work has shown that incubation of this Zn2+ metalloenzyme with 2,6-dipicolinic acid, 8-hydroxyquinoline-5-sulfonic acid, or o-phenanthroline results in inactivation by Zn2+ removal by a reaction pathway involving formation of a ternary enzyme-Zn2+-chelator complex which subsequently dissociates to yield apoenzyme and the Zn2+-chelate (K. P. Brooks, E. A. Jones, B. D. Kim, and E. G. Sander, (1983) Arch. Biochem. Biophys. 226, 469-483). In the present work, the pH dependence of chelator inactivation is studied. The equilibrium constant for formation of the ternary complex is strongly pH dependent and increases with decreasing pH for all three chelators. There is a positive correlation between the value of the equilibrium constant observed for each chelator and the value of its stability constant for formation of Zn2+-chelate. The affinity of the chelators for the enzyme increases in the order 8-hydroxyquinoline-5-sulfonic acid greater than o-phenanthroline greater than 2,6-dipicolinic acid. The first-order rate constant for breakdown of the ternary complex to yield apoenzyme and Zn2+-chelate is invariant with pH for a given chelator but is different for each chelator, increasing in the reverse order. The pH dependence of the inactivation shows that two ionizable groups on the enzyme are involved in the inactivation. On the other hand, the steady-state kinetic behavior of the enzyme is well-described by ionization of a single group with a pK of 6.0 in the free enzyme. The basic form of the group is required for catalysis; protonation of the group decreases both Vmax and the apparent affinity for substrate. Conversely, binding of substrate decreases the pK of this group to about 5. L-Dihydroorotic acid is shown to be a competitive inhibitor of dihydropyrimidine amidohydrolase. Binding of L-dihydroorotic acid

  7. Porous dimanganese trioxide microflowers derived from microcoordinations for flexible solid-state asymmetric supercapacitors

    NASA Astrophysics Data System (ADS)

    Pang, Huan; Li, Xinran; Li, Bing; Zhang, Yizhou; Zhao, Qunxing; Lai, Wen-Yong; Huang, Wei

    2016-06-01

    Dimanganese trioxide microflowers are easily obtained from a Mn(ii) 8-hydroxyquinoline microcoordination after calcination in air. We also look into the possible formation mechanism of the flower-like morphology, and find that the reaction time affects the morphology of the coordination. Furthermore, the as-prepared porous Mn2O3 microflowers are made of many nanoplates which form many nanogaps and nanochannels. Interestingly, the assembled electrode based on the as-prepared porous Mn2O3 microflowers proves to be a high-performance electrode material for supercapacitors. The electrode shows a specific capacitance of 994 F g-1, which can work well even after 4000 cycles at 0.75 A g-1. More importantly, the porous Mn2O3 microflowers and activated carbons are assembled into a high-performance flexible solid-state asymmetric supercapacitor with a specific capacitance of 312.5 mF cm-2. The cycle test shows that the device can offer 95.6% capacity of the initial capacitance at 2.0 mA cm-2 after 5000 cycles with little decay. The maximum energy density of the device can achieve 6.56 mWh cm-3 and the maximum power density can also achieve 283.5 mW cm-3, which are among the best results for manganese based materials.Dimanganese trioxide microflowers are easily obtained from a Mn(ii) 8-hydroxyquinoline microcoordination after calcination in air. We also look into the possible formation mechanism of the flower-like morphology, and find that the reaction time affects the morphology of the coordination. Furthermore, the as-prepared porous Mn2O3 microflowers are made of many nanoplates which form many nanogaps and nanochannels. Interestingly, the assembled electrode based on the as-prepared porous Mn2O3 microflowers proves to be a high-performance electrode material for supercapacitors. The electrode shows a specific capacitance of 994 F g-1, which can work well even after 4000 cycles at 0.75 A g-1. More importantly, the porous Mn2O3 microflowers and activated carbons are

  8. Multi-Target Directed Donepezil-Like Ligands for Alzheimer's Disease.

    PubMed

    Unzeta, Mercedes; Esteban, Gerard; Bolea, Irene; Fogel, Wieslawa A; Ramsay, Rona R; Youdim, Moussa B H; Tipton, Keith F; Marco-Contelles, José

    2016-01-01

    HIGHLIGHTS ASS234 is a MTDL compound containing a moiety from Donepezil and the propargyl group from the PF 9601N, a potent and selective MAO B inhibitor. This compound is the most advanced anti-Alzheimer agent for preclinical studies identified in our laboratory.Derived from ASS234 both multipotent donepezil-indolyl (MTDL-1) and donepezil-pyridyl hybrids (MTDL-2) were designed and evaluated as inhibitors of AChE/BuChE and both MAO isoforms. MTDL-2 showed more high affinity toward the four enzymes than MTDL-1.MTDL-3 and MTDL-4, were designed containing the N-benzylpiperidinium moiety from Donepezil, a metal- chelating 8-hydroxyquinoline group and linked to a N-propargyl core and they were pharmacologically evaluated.The presence of the cyano group in MTDL-3, enhanced binding to AChE, BuChE and MAO A. It showed antioxidant behavior and it was able to strongly complex Cu(II), Zn(II) and Fe(III).MTDL-4 showed higher affinity toward AChE, BuChE.MTDL-3 exhibited good brain penetration capacity (ADMET) and less toxicity than Donepezil. Memory deficits in scopolamine-lesioned animals were restored by MTDL-3.MTDL-3 particularly emerged as a ligand showing remarkable potential benefits for its use in AD therapy. Alzheimer's disease (AD), the most common form of adult onset dementia, is an age-related neurodegenerative disorder characterized by progressive memory loss, decline in language skills, and other cognitive impairments. Although its etiology is not completely known, several factors including deficits of acetylcholine, β-amyloid deposits, τ-protein phosphorylation, oxidative stress, and neuroinflammation are considered to play significant roles in the pathophysiology of this disease. For a long time, AD patients have been treated with acetylcholinesterase inhibitors such as donepezil (Aricept®) but with limited therapeutic success. This might be due to the complex multifactorial nature of AD, a fact that has prompted the design of new Multi-Target-Directed Ligands

  9. Multi-Target Directed Donepezil-Like Ligands for Alzheimer's Disease

    PubMed Central

    Unzeta, Mercedes; Esteban, Gerard; Bolea, Irene; Fogel, Wieslawa A.; Ramsay, Rona R.; Youdim, Moussa B. H.; Tipton, Keith F.; Marco-Contelles, José

    2016-01-01

    HIGHLIGHTS ASS234 is a MTDL compound containing a moiety from Donepezil and the propargyl group from the PF 9601N, a potent and selective MAO B inhibitor. This compound is the most advanced anti-Alzheimer agent for preclinical studies identified in our laboratory.Derived from ASS234 both multipotent donepezil-indolyl (MTDL-1) and donepezil-pyridyl hybrids (MTDL-2) were designed and evaluated as inhibitors of AChE/BuChE and both MAO isoforms. MTDL-2 showed more high affinity toward the four enzymes than MTDL-1.MTDL-3 and MTDL-4, were designed containing the N-benzylpiperidinium moiety from Donepezil, a metal- chelating 8-hydroxyquinoline group and linked to a N-propargyl core and they were pharmacologically evaluated.The presence of the cyano group in MTDL-3, enhanced binding to AChE, BuChE and MAO A. It showed antioxidant behavior and it was able to strongly complex Cu(II), Zn(II) and Fe(III).MTDL-4 showed higher affinity toward AChE, BuChE.MTDL-3 exhibited good brain penetration capacity (ADMET) and less toxicity than Donepezil. Memory deficits in scopolamine-lesioned animals were restored by MTDL-3.MTDL-3 particularly emerged as a ligand showing remarkable potential benefits for its use in AD therapy. Alzheimer's disease (AD), the most common form of adult onset dementia, is an age-related neurodegenerative disorder characterized by progressive memory loss, decline in language skills, and other cognitive impairments. Although its etiology is not completely known, several factors including deficits of acetylcholine, β-amyloid deposits, τ-protein phosphorylation, oxidative stress, and neuroinflammation are considered to play significant roles in the pathophysiology of this disease. For a long time, AD patients have been treated with acetylcholinesterase inhibitors such as donepezil (Aricept®) but with limited therapeutic success. This might be due to the complex multifactorial nature of AD, a fact that has prompted the design of new Multi-Target-Directed Ligands

  10. A Planar, Chip-Based, Dual-Beam Refractometer Using an Integrated Organic Light Emitting Diode (OLED) Light Source and Organic Photovoltaic (OPV) Detectors

    PubMed Central

    Ratcliff, Erin L.; Veneman, P. Alex; Simmonds, Adam; Zacher, Brian; Huebner, Daniel

    2010-01-01

    We present a simple chip-based refractometer with a central organic light emitting diode (OLED) light source and two opposed organic photovoltaic (OPV) detectors on an internal reflection element (IRE) substrate, creating a true dual-beam sensor platform. For first-generation platforms, we demonstrate the use of a single heterojunction OLED based on electroluminescence emission from an Alq3/TPD heterojunction (tris-(8-hydroxyquinoline)aluminum/N,N′-Bis(3-methylphenyl)-N,N′-diphenylbenzidine) and light detection with planar heterojunction pentacene/C60 OPVs. The sensor utilizes the considerable fraction of emitted light from conventional thin film OLEDs that is coupled into guided modes in the IRE instead of into the forward (display) direction. A ray-optics description is used to describe light throughput and efficiency-limiting factors for light coupling from the OLED into the substrate modes, light traversing through the IRE substrate, and light coupling into the OPV detectors. The arrangement of the OLED at the center of the chip provides for two sensing regions, a “sample” and “reference” channel, with detection of light by independent OPV detectors. This configuration allows for normalization of the sensor response against fluctuations in OLED light output, stability, and local fluctuations (temperature) which might influence sensor response. The dual beam configuration permits significantly enhanced sensitivity to refractive index changes relative to single-beam protocols, and is easily integrated into a field-portable instrumentation package. Changes in refractive index (ΔR.I.) between 10−2 and 10−3 R.I. units could be detected for single channel operation, with sensitivity increased to ΔR.I. ≈ 10−4 units when the dual beam configuration is employed. PMID:20218580

  11. Light-Dependent Reduction of Hydrogen Peroxide by Ruptured Pea Chloroplasts 1

    PubMed Central

    Jablonski, Peter P.; Anderson, John W.

    1982-01-01

    Ruptured pea (Pisum sativum cv. Massey Gem) chloroplasts exhibited ascorbate peroxidase activity as determined by H2O2-dependent oxidation of ascorbate and ascorbate-dependent reduction of H2O2. The ratio of ascorbate peroxidase to NADP-glyceraldehyde 3-phosphate dehydrogenase activity was constant during repeated washing of isolated chloroplasts. This indicates that the ascorbate peroxidase is a chloroplast enzyme. The pH optimum of ascorbate peroxidase activity was 8.2 and the Km value for ascorbate was 0.6 millimolar. Pyrogallol, glutathione, and NAD(P)H did not substitute for ascorbate in the enzyme catalyzed reaction. The enzyme was inhibited by NaN3, KCN, and 8-hydroxyquinoline but not ZnCl2 or iodoacetate. The ascorbate peroxidase activity of sonicated chloroplasts was inhibited by light but not in the presence of substrate concentrations of ascorbate. Illuminated ruptured chloroplasts, in the presence of 50 micromolar NADP(H), 2 millimolar l-ascorbate, and substrate concentrations of oxidized or reduced glutathione, catalyzed O2 evolution when H2O2 was added. Since the reaction was not inhibited by 0.1 millimolar NaN3 and did not occur in the dark, it was concluded that catalase was not involved. Light-plus-H2O2-dependent O2 evolution consisted of two distinct phases. The first phase was ascorbate-dependent and typically represented 10% of the total amount of O2 evolved. The second phase was dependent on ascorbate and glutathione. The properties of the second phase were consistent with the operation of light-coupled glutathione reductase sequentially coupled to glutathione dehydrogenase and ascorbate peroxidase. PMID:16662413

  12. Comparison of kinetic properties of amine oxidases from sainfoin and lentil and immunochemical characterization of copper/quinoprotein amine oxidases.

    PubMed

    Zajoncová, L; Frébort, I; Luhová, L; Sebela, M; Galuszka, P; Pec, P

    1999-01-01

    Kinetic properties of novel amine oxidase isolated from sainfoin (Onobrychis viciifolia) were compared to those of typical plant amine oxidase (EC 1.4.3.6) from lentil (Lens culinaris). The amine oxidase from sainfoin was active toward substrates, such as 1,5-diaminopentane (cadaverine) with K(m) of 0.09 mM and 1,4-diaminobutane (putrescine) with K(m) of 0.24 mM. The maximum rate of oxidation for cadaverine at saturating concentration was 2.7 fold higher than that of putrescine. The amine oxidase from lentil had the maximum rate for putrescine comparable to the rate of sainfoin amine oxidase with the same substrate. Both amine oxidases, like other plant Cu-amine oxidases, were inhibited by substrate analogs (1,5-diamino-3-pentanone, 1,4-diamino-2-butanone and aminoguanidine), Cu2+ chelating agents (diethyltriamine, 1,10-phenanthroline, 8-hydroxyquinoline, 2,2'-bipyridyl, imidazole, sodium cyanide and sodium azide), some alkaloids (L-lobeline and cinchonine), some lathyrogens (beta-aminopropionitrile and aminoacetonitrile) and other inhibitors (benzamide oxime, acetone oxime, hydroxylamine and pargyline). Tested by Ouchterlony's double diffusion in agarose gel, polyclonal antibodies against the amine oxidase from sainfoin, pea and grass pea cross-reacted with amine oxidases from several other Fabaceae and from barley (Hordeum vulgare) of Poaceae, while amine oxidase from the filamentous fungus Aspergillus niger did not cross-react at all. However, using Western blotting after SDS-PAGE with rabbit polyclonal antibodies against the amine oxidase from Aspergillus niger, some degree of similarity of plant amine oxidases from sainfoin, pea, field pea, grass pea, fenugreek, common melilot, white sweetclover and Vicia panonica with the A. niger amine oxidase was confirmed. PMID:10092944

  13. Highly luminescent material based on Alq3:Ag nanoparticles.

    PubMed

    Salah, Numan; Habib, Sami S; Khan, Zishan H

    2013-09-01

    Tris (8-hydroxyquinoline) aluminum (Alq3) is an organic semiconductor molecule, widely used as an electron transport layer, light emitting layer in organic light-emitting diodes and a host for fluorescent and phosphorescent dyes. In this work thin films of pure and silver (Ag), cupper (Cu), terbium (Tb) doped Alq3 nanoparticles were synthesized using the physical vapor condensation method. They were fabricated on glass substrates and characterized by X-ray diffraction, scanning electron microscope (SEM), energy dispersive spectroscopy, atomic force microscope (AFM), UV-visible absorption spectra and studied for their photoluminescence (PL) properties. SEM and AFM results show spherical nanoparticles with size around 70-80 nm. These nanoparticles have almost equal sizes and a homogeneous size distribution. The maximum absorption of Alq3 nanoparticles is observed at 300 nm, while the surface plasmon resonant band of Ag doped sample appears at 450 nm. The PL emission spectra of Tb, Cu and Ag doped Alq3 nanoparticles show a single broad band at around 515 nm, which is similar to that of the pure one, but with enhanced PL intensity. The sample doped with Ag at a concentration ratio of Alq3:Ag = 1:0.8 is found to have the highest PL intensity, which is around 2 times stronger than that of the pure one. This enhancement could be attributed to the surface plasmon resonance of Ag ions that might have increased the absorption and then the quantum yield. These remarkable result suggest that Alq3 nanoparticles incorporated with Ag ions might be quite useful for future nano-optoelectronic devices. PMID:23653126

  14. Precise isotopic analysis of Mo in seawater using multiple collector-inductively coupled mass spectrometry coupled with a chelating resin column preconcentration method.

    PubMed

    Nakagawa, Yusuke; Firdaus, M Lutfi; Norisuye, Kazuhiro; Sohrin, Yoshiki; Irisawa, Keita; Hirata, Takafumi

    2008-12-01

    It is widely recognized that the natural isotopic variation of Mo can provide crucial information about the geochemical circulation of Mo, and the ocean is an important reservoir of Mo. To obtain precise isotopic data on Mo in seawater samples using multiple collector-inductively coupled plasma mass spectrometry (MC-ICPMS), we have developed a preconcentration technique using 8-hydroxyquinoline bonded covalently to a vinyl polymer resin (TSK-8HQ). By optimizing the procedure, Mo in seawater could be effectively separated from matrix elements such as alkali, alkaline earth, and transition metals. With this technique, even with a 50-fold enrichment factor, the changes in the 98Mo/95Mo ratio during preconcentration were smaller than twice the standard deviation (SD) in this study. Mass discrimination of Mo isotopes during the measurement was externally corrected for by normalizing 86Sr/88Sr to 0.1194 using an exponential law. We evaluated delta98/95Mo to a precision of +/- 0.08 per thousand (+/-2 SD); this value was found to be less than one-third of previous reported values. Moreover, we were able to determine an accurate ratio for every pair of stable Mo isotopes, which was impossible with previous methods owing to the isobaric interference from the external elements (Zr and Ru). In this study, delta92/98Mo in seawater was first determined so that it had the smallest relative error. We applied the proposed method to four kinds of seawater samples. The Mo compositions were constant among them, with average delta98/95Mo and delta92/98Mo values of 2.45 +/- 0.11 and -4.94 +/- 0.09 per thousand (+/-2 SD), respectively. Our data indicate that seawater is enriched in heavy Mo isotopes than previously reported. PMID:19551942

  15. Curcumin reduces the toxic effects of iron loading in rat liver epithelial cells

    PubMed Central

    Messner, Donald J.; Sivam, Gowsala; Kowdley, Kris V.

    2008-01-01

    Background/aims Iron overload can cause liver toxicity and increase the risk of liver failure or hepatocellular carcinoma in humans. Curcumin (diferuloylmethane), a component of the food spice turmeric, has antioxidant, iron binding, and hepatoprotective properties. The aim of this study was to quantify its effects on iron overload and resulting downstream toxic effects in cultured T51B rat liver epithelial cells. Methods T51B cells were loaded with ferric ammonium citrate (FAC) with or without the iron delivery agent 8-hydroxyquinoline. Cytotoxicity was measured by MTT assay. Iron uptake and iron bioavailability were documented by chemical assay, quench of calcein fluorescence, and ferritin induction. Reactive oxygen species (ROS) were measured by fluorescence assay using 2′,7′-dichlorodihydrofluorescein diacetate. Oxidative stress signaling to jnk, c-jun, and p38 was measured by western blot with phospho-specific antibodies. Results Curcumin bound iron, but did not block iron uptake or bioavailability in T51B cells given FAC. However, it reduced cytotoxicity, blocked generation of ROS, and eliminated signaling to cellular stress pathways caused by iron. Inhibition was observed over a wide range of FAC concentrations (50 – 500 μM), with an apparent IC50 in all cases between 5 and 10 μM curcumin. In contrast, desferoxamine blocked both iron uptake and toxic effects of iron at concentrations that depended on the FAC concentration. Effects of curcumin also differed from those of α-tocopherol, which did not bind iron and was less effective at blocking iron-stimulated ROS generation. Conclusions Curcumin reduced iron-dependent oxidative stress and iron toxicity in T51B cells without blocking iron uptake. PMID:18492020

  16. Chromosome number and cytogenetics of Euphorbia heterophylla L.

    PubMed

    Aarestrup, J R; Karam, D; Fernandes, G W

    2008-01-01

    Euphorbia heterophylla L. (Euphorbiaceae) is a herbaceous species of great economic importance due to its invasive potential and consequent damage to agriculture and pasture land. For the first time, we provide information on its chromosome number, morphology, and behavior of mitotic chromosomes. Seeds were germinated and submitted to four treatments to obtain metaphases: 0.5% colchicine for 2 to 5 h, at ambient temperature; 0.5% colchicine for 16 to 24 h; 0.0029 M 8-hydroxyquinoline (8-HQ) for 2 to 5 h at ambient temperature, and 0.0029 M 8-HQ for 16 to 24 h at 4 degrees C. The material was then fixed in methanol:acetic acid (3:1) and kept at -20 degrees C for 24 h. Roots were macerated in the enzyme solution of Flaxzyme (NOVO FERMENT)-distilled water (1:40) at 34 degrees C for 2 h and later fixed again. Chromosome preparations were obtained by the dissociation of the apical meristems. The best chromosome preparations were obtained with the use of 8-HQ for 21 h 30 min at 4 degrees C. E. heterophylla showed 2n = 28 chromosomes. The short arm of the largest pair of chromosomes of the complement (pair number 1) displayed a secondary constriction while the nucleolus was observed in the interphasic cell. Structural rearrangements were also observed in the E. heterophylla L. genome. The genomic instability associated with polyploidy may be the result of selection shaped by environmental adaptations and/or human-induced manipulation through agricultural practices. PMID:18393225

  17. Neutrophil killing of human umbilical vein endothelial cells is oxygen radical-mediated and enhanced by TNF-. alpha

    SciTech Connect

    Dame, M.K.; Varani, J.; Weinberg, J.M.; Ward, P.A. )

    1991-03-11

    Human umbilical vein endothelial cells are sensitive to killing by activated human neutrophils. Killing is inhibited in the presence of catalase and deferoxamine mesylate but not soybean trypsin inhibitor. Reagent hydrogen peroxide can substitute for activated neutrophils in producing endothelial cell injury. These data suggest that lethal injury is due to the production of oxygen radicals by activated neutrophils. In these respects, the human umbilical vein endothelial cells are similar to rat pulmonary artery endothelial cells in that pretreatment with TNF-{alpha} increases sensitivity to injury by activated neutrophils. In part, the increased endothelial cell sensitivity to killing by neutrophils may be due to up-regulation of surface adhesion molecules. However, it was observed that cells passaged more than two times in culture did not demonstrate increased killing after treatment with TNF-{alpha} while up-regulation of neutrophil adhesion could be detected through several additional passages. Although the human umbilical vein endothelial cells are qualitatively similar to rat pulmonary artery endothelial cells in their sensitivity to killing, they are quantitatively much more resistant. What accounts for the relative resistance of the human umbilical vein endothelial cells is not fully understood. In the rat pulmonary artery endothelial cells, killing is known to be dependent on an intraendothelial source of iron. Pre-treatment of the human umbilical vein endothelial cells with 8-hydroxyquinoline-bound iron increased their sensitivity to oxidant injury. These data suggest that the availability of iron within the human umbilical vein endothelial cells may be a limiting factor in sensitivity to oxygen radical-mediated injury.

  18. Determination of manganese- and manganese-containing fungicides with lucigenin-Tween-20-enhanced chemiluminescence detection.

    PubMed

    Yaqoob, Mohammad; Asghar, Mohammad; Nabi, Abdul

    2015-11-01

    A flow-injection (FI) method is reported for the determination of Mn(II), maneb and mancozeb fungicides based on the catalytic effect of Mn(II) on the oxidation of lucigenin and dissolved oxygen in a basic solution. The Tween-20 surfactant has been reported for first time to enhance lucigenin chemiluminescence (CL) intensity in the presence of Mn(II) (53%) and maneb and mancozeb (89%). The calibration graphs were linear in the concentration range of 0.001-1.5 mg L(-1) (R(2) = 0.9982 (n = 11) with a limit of detection (S/N = 3) of 0.1 µg L(-1) for Mn(II) and 0.01-3.0 mg L(-1) [R(2) = 0.9989 and R(2) = 0.9992 (n = 6)] with a limit of detection (S/N =3) of 1.0 µg L(-1) for maneb and mancozeb respectively. Injection throughputs of 90 and 120 h(-1) for Mn(II) and maneb and mancozeb respectively, and relative standard deviations of 1.0-3.4% were obtained in the concentration range studied. The experimental variables, e.g., reagents concentrations, flow rates, sample volume, and photomultiplier tube voltage, were optimized and potential interferences were investigated. The analysis of Mn(II) in river water reference materials (SLRS-4 and SLRS-5) showed good agreement with the certified values incorporating an on-line 8-hydroxyquinoline chelating column in the manifold for removing interfering metal ions. Recoveries for maneb and mancozeb were in the range of 92 ± 5 to 104 ± 3% and 91 ± 2 to 100 ± 4% (n = 3) respectively. The effect of 30 other pesticides (fungicides, herbicides and insecticides) was also examined in the lucigenin-Tween-20 CL system. PMID:25640332

  19. Thermal detection of trapped charge carriers in organic transport materials

    NASA Astrophysics Data System (ADS)

    von Malm, Norwin; Steiger, Juergen; Finnberg, Torsten; Schmechel, Roland; von Seggern, Heinz

    2003-03-01

    The effect of trap states on the transport and luminescence properties of organic light emitting diodes (OLEDs) is studied. For trap level detection energy resolved thermally stimulated current (TSC) measurements known as fractional glow are utilized to determine the density of occupied states (DOOS) in various organic semiconductors such as the small molecule systems Alq3 [aluminum tris(8-hydroxyquinoline)], 1-NaphDATA {4,4',4"-tris-[N-(1-naphtyl)-N-phenylamino]-triphenylamine} and α-NPD [N,N'-di-(1-naphthyl)-N,N'-diphenylbenzidine] and the polymeric semiconductor MDMO-PPV {poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene]}. Characteristic differences in the trap spectra are obtained and interpreted in terms of possible structural and compositional origins of the investigated materials. In order to judge the formation process of traps and their practical consequences on the charge carrier transport I-V and L-V characteristics of 1-NaphDATA doped α-NPD devices and α-NPD doped 1-NaphDATA devices were compared to respective non-doped samples. A clearly reduced current and luminescence was found only in the former case. It was possible to conclude that the detected electronic trap states either act as hole traps or as scattering centers. Furthermore, pulsed transport studies on ITO/α-NPD/Alq3/Al devices show thte critical influence of traps on the dynamical performance of the charge transport. In a two-pulse experiment the carrier injection and trap depletion can be separated.

  20. Synthesis and characterization of binary and ternary complexes of Co(II), Ni(II), Cu(II) and Zn(II) ions based on 4-aminotoluene-3-sulfonic acid.

    PubMed

    Faheim, Abeer A; Abdou, Safaa N; Abd El-Wahab, Zeinab H

    2013-03-15

    Salicylidene (4-aminotoluene-3-sulfonic acid) Schiff base ligand H(2)L, and its binary and ternary Co(II), Ni(II), Cu(II) and Zn(II) complexes using 8-hydroxyquinoline (8-HOqu) and 2-aminopyridine (2-Ampy) as secondary ligands have been synthesised and characterized via elemental analysis, spectral data (IR, (1)H NMR, mass and solid reflectance), molar conductance, magnetic moment, TG-DSC measurements and XRPD analysis. Correlation of all spectroscopic data suggest that H(2)L ligand acts as monoanionic terdentate ligand with ONO sites coordinating to the metal ions via deprotonated phenolic-O, azomethine-N and sulfonate-O while 2-Ampy behaves as a neutral monodentate ligand via amino group-N and 8-HOqu behaves as a monoanionic bidentate ligand through the ring-N and deprotonated phenolic-O. The thermal behavior of these complexes shows that the coordinated water molecules were eliminated from the complexes at relatively higher temperatures than the hydrated water and there are two routes in removal of coordinated water molecules. All complexes have mononuclear structure and the tetrahedral, square planar or an octahedral geometry have been proposed. The ligand and its complexes have been screened for their antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Salmonella typhimurium, Candida albicans and Aspergillus fumigatus. Among the synthesised compounds, the binary and ternary Ni(II) complexes, (2, 8 and 10) and ternary Zn(II) complex, (12) were found to be very effective against Candida albicans and Bacillus subtilis than all other complexes with MICs of 2 and 8 μg/mL, respectively.

  1. EFFECT OF CHELATING AGENTS ON THE GROWTH OF ESCHERICHIA COLI IN SEAWATER.

    PubMed

    JONES, G E

    1964-03-01

    Jones, Galen E. (Scripps Institution of Oceanography, University of California, La Jolla). Effect of chelating agents on the growth of Escherichia coli in seawater. J. Bacteriol. 87:483-499. 1964.-Escherichia coli did not grow at 37 C, or grew only after a prolonged lag phase in filter-sterilized basal seawater medium (synthetic or natural seawater supplemented with glucose, NH(4)Cl, and K(2)HPO(4)). When this basal medium was enriched with 0.01% or less organic matter, such as casein hydrolysate, peptone, or yeast extract, growth always occurred after a short lag phase. Adding 10(-5)m cysteine or autoclaving the seawater gave a similar effect. A variety of organic chelating agents (histidine, glycine, methionine, glycylglycine, 8-hydroxyquinoline, thioglycolic acid, o-phenanthroline, disodium ethylenediaminetetraacetic acid, etc.) reversed the toxicity of filter-sterilized basal seawater medium in concentrations predictable from stability constants. Even metal-complexing agents such as Na(2)S(2)O(3), Na(2)S, and NaCN in appropriate concentrations reversed toxicity. The quality of the distilled water and the treatment of glassware had a significant effect on the growth of E. coli in basal seawater medium. It was concluded that iodate is probably not the toxic substance for E. coli in seawater, since relatively high concentrations were stimulatory. The inhibition resulting from the individual salts of synthetic seawater was proportional to their concentration; NaCl was most inhibitory. This toxicity is believed to be derived from trace impurities in the reagent-grade chemicals used to prepare synthetic seawater. Evidence was also found for the toxicity of heavy metals in natural seawater. Heavy metals in seawater appear to inhibit growth but not respiration. PMID:14127563

  2. Inactivation of botulinum and tetanus toxins by chelators.

    PubMed Central

    Bhattacharyya, S D; Sugiyama, H

    1989-01-01

    Purified type A botulinum toxin of about 10(6) mouse 50% lethal doses per ml was greater than 99.9% inactivated when incubated at pH 7.4 for 30 min at 37 degrees C in 20 mM 1,10-phenanthroline (PTL) or 2,2'-dipyridyl (DPD) and was 96% inactivated when incubated in 70 mM 8-hydroxyquinoline-5-sulfonic acid (HQL), but was not affected when incubated in 200 mM EDTA. When used as a representative of the chelating agents, PTL inactivated greater than or equal to 99.9% of toxicity in the culture filtrate of C. botulinum type A, B, and E strains. Highly purified tetanus toxin at 2.5 x 10(5) 50% lethal doses per ml lost all toxicity in 40 mM PTL or 150 mM DPD but was not detectably affected by 100 mM HQL (the highest concentration possible). Toxin inactivation by 20 mM PTL was completely blocked when the PTL was prereacted with an equimolar amount of Zn2+ and significantly reduced when it was preincubated with one-third its molar amount of Fe2+. DPD at 20 mM had little toxin-inactivating potency when preincubated with an equimolar amount of Zn2+ and only some of this potency when preincubated with an equimolar amount of Fe2+. Toxicity was not recovered by adding Zn2+ or Fe2+ to PTL-treated toxin. Neutron activation analysis of type A toxin showed that for each toxin molecule present, there was 1 atom of Fe, 0.4 atom of Zn, and 22 to 55 atoms each of Ca and Mg. The biological activity of botulinum toxin seems to depend on a metal component, which is likely to be Fe. PMID:2506129

  3. Significance of physicochemical forms of storage in microalgae in predicting copper transfer to filter-feeding oysters (Crassostrea gigas).

    PubMed

    Amiard-Triquet, Claude; Berthet, Brigitte; Joux, Lamia; Perrein-Ettajani, Hanane

    2006-02-01

    Copper distribution has been examined in two microalgae (Haslea ostrearia, Diatom; Tetraselmis suecica, Prasinophyceae) exposed to Cu at 30 microg/L(-1). Exchangeable copper linked at the cell surface was desorbed using 8-hydroxyquinoline-5-sulfonate as complexing agent. Then, incorporated copper was separated between soluble and insoluble fractions. In addition, algae were resuspended in acid solutions, the pHs of which covered the range existing in the digestive tract of bivalves. Considering that the soluble fraction is the most easily transferred in the food chain and that exchangeable Cu is easily desorbed, the percentages of Cu potentially available in microalgae have been assessed. These percentages have been compared with those retained in oysters Crassostrea gigas fed with contaminated microalgae in previous studies. In H. ostrearia, the potentially available fraction of Cu (90%) was very similar to the percentage retained by oysters (93%) when the bivalves were acclimated to this food for 3 weeks. Only half (21%) of the potentially available Cu of T. suecica (42%) was readily assimilated in oysters after 3 weeks. This is in agreement with the results of the desorption tests at physiological pHs which showed that only 15-25% of Cu was lost, despite solubilization of other constituents of T. suecica as demonstrated by the decrease in their dry weight. Bioavailability determined from metal speciation in food allows a relevant prediction of the trophic transfer in the case of H. ostrearia, but caution is recommended in generalizing this mode of assessment as shown in the case of T. suecica.

  4. Mg2+ binding and structural stability of mature and in vitro synthesized unmodified Escherichia coli tRNAPhe.

    PubMed

    Serebrov, V; Vassilenko, K; Kholod, N; Gross, H J; Kisselev, L

    1998-06-01

    Mature tRNAPhe from Escherichia coli and the transcript of its gene lacking modified nucleotides were compared by a variety of physical techniques. Melting experiments revealed that at a low Mg2+level the transcript was partially denatured, while the mature tRNA possessed intact tertiary interactions. Mg2+binding to both tRNAs was studied by CD and UV techniques as well as by using the Mg2+-sensitive fluorescence indicator, 8-hydroxyquinoline 5-sulfonic acid. Both tRNA forms exhibited a single strong Mg2+-binding site, its dissociation constant was 10-fold higher for the transcript. Conformational changes in response to Mg2+ addition measured by CD and UV spectrometry revealed no difference for the estimated binding cooperativity and strong differences for affinities of Mg2+-binding sites for the two tRNA forms. Conformational transitions in mature and in in vitro synthesized tRNA required the binding of two Mg2+ ions per molecule and therefore should be associated not only with a single strong binding site. The Mg2+ dependence of Stokes radii measured by gel-filtration revealed insignificant differences between the overall sizes of the two tRNA forms at physiological Mg2+ levels (>1 mM). Taken together, these results suggest that modified nucleotides stabilize tertiary interactions and increase the structure stability without affecting the mechanism of Mg2+binding and overall folding of the tRNA molecule. This conclusion is supported by the known biological activity of the E. coli tRNAPhe gene transcript.

  5. Characterization of the folate salvage enzyme p-aminobenzoylglutamate hydrolase in plants.

    PubMed

    Bozzo, Gale G; Basset, Gilles J C; Naponelli, Valeria; Noiriel, Alexandre; Gregory, Jesse F; Hanson, Andrew D

    2008-01-01

    Folates break down in vivo to give pterin and p-aminobenzoylglutamate (pABAGlu) fragments, the latter usually having a polyglutamyl tail. Pilot studies have shown that plants can hydrolyze pABAGlu and its polyglutamates to p-aminobenzoate, a folate biosynthesis precursor. The enzymatic basis of this hydrolysis was further investigated. pABAGlu hydrolase activity was found in all species and organs tested; activity levels implied that the proteins responsible are very rare. The activity was located in cytosol/vacuole and mitochondrial fractions of pea (Pisum sativum L.) leaves, and column chromatography of the activity from Arabidopsis tissues indicated at least three peaks. A major activity peak from Arabidopsis roots was purified 86-fold by a three-column procedure; activity loss during purification exceeded 95%. Size exclusion chromatography gave a molecular mass of approximately 200 kDa. Partially purified preparations showed a pH optimum near 7.5, a Km value for pABAGlu of 370 microM, and activity against folic acid. Activity was relatively insensitive to thiol and serine reagents, but was strongly inhibited by 8-hydroxyquinoline-5-sulfonic acid and stimulated by Mn2+, pointing to a metalloenzyme. The Arabidopsis genome was searched for proteins similar to Pseudomonas carboxypeptidase G, which contains zinc and is the only enzyme yet confirmed to attack pABAGlu. The sole significant matches were auxin conjugate hydrolase family members and the At4g17830 protein. None was found to have significant pABAGlu hydrolase activity, suggesting that this activity resides in hitherto unrecognized enzymes. The finding that Arabidopsis has folate-hydrolyzing activity points to an enzymatic component of folate degradation in plants.

  6. Identification and characterization of a metalloprotease activity from Helicobacter pylori.

    PubMed Central

    Windle, H J; Kelleher, D

    1997-01-01

    Helicobacter pylori produces a metalloprotease with a native molecular size of approximately 200 kDa, as determined by size-exclusion chromatography. Subcellular distribution studies demonstrated that the activity was associated with the outer membrane fraction of the bacterium. In addition, the protease was secreted by the bacterium when grown in liquid culture. The enzyme activity was measured by hydrolysis of azocasein and biotinylated casein and exhibited optimal caseinolytic activity at pH 8.0 (37 degrees C). The activity was inhibited by EDTA, 1,10-phenanthroline, phosphoramidon, pyridine-2,6-dicarboxylic acid, and 8-hydroxyquinoline-5-sulfonic acid (HQSA). Inhibition by HQSA was reversed by zinc, whereas inhibition due to EDTA was reversed by excess calcium, thus indicating that the enzyme was a zinc-dependent, calcium-stabilized endoproteinase. Furthermore, titration with Zn2+ of a desalted, active-site zinc-chelated preparation of the protease demonstrated that Zn2+ was essential for activity. Leupeptin, phenylmethylsulfonyl fluoride, E-64, pepstatin A, dithiothreitol, and 2-mercaptoethanol had no effect on enzymatic activity. Addition of Ca2+ or Mg2+ to the incubation medium resulted in approximately a twofold stimulation of the azocaseinolytic activity of the enzyme. The protease was stably expressed since it was active even after repeated subculture of the bacterium. Bovine serum albumin, hide powder azure, and elastin-Congo red remained intact even after prolonged exposure to the enzyme. The surface expression of this metalloprotease activity raises the possibility that this enzyme may be involved in the proteolysis of a variety of host proteins in vivo and thereby contributes to gastric pathology. PMID:9234765

  7. TrzN from Arthrobacter aurescens TC1 Is a Zinc Amidohydrolase

    PubMed Central

    Shapir, Nir; Pedersen, Charlotte; Gil, Omer; Strong, Lisa; Seffernick, Jennifer; Sadowsky, Michael J.; Wackett, Lawrence P.

    2006-01-01

    TrzN, the broad-specificity triazine hydrolase from Arthrobacter and Nocardioides spp., is reportedly in the amidohydrolase superfamily of metalloenzymes, but previous studies suggested that a metal was not required for activity. To help resolve that conundrum, a double chaperone expression system was used to produce multimilligram quantities of functionally folded, recombinant TrzN. The TrzN obtained from Escherichia coli (trzN) cells cultured with increasing zinc in the growth medium showed corresponding increases in specific activity, and enzyme obtained from cells grown with 500 μM zinc showed maximum activity. Recombinant TrzN contained 1 mole of Zn per mole of TrzN subunit. Maximally active TrzN was not affected by supplementation with most metals nor by EDTA, consistent with previous observations (E. Topp, W. M. Mulbry, H. Zhu, S. M. Nour, and D. Cuppels, Appl. Environ. Microbiol. 66:3134-3141, 2000) which had led to the conclusion that TrzN is not a metalloenzyme. Fully active native TrzN showed a loss of greater than 90% of enzyme activity and bound zinc when treated with the metal chelator 8-hydroxyquinoline-5-sulfonic acid. While exogenously added zinc or cobalt restored activity to metal-depleted TrzN, cobalt supported lower activity than did zinc. Iron, manganese, nickel, and copper did not support TrzN activity. Both Zn- and Co-TrzN showed different relative activities with different s-triazine substrates. Co-TrzN showed a visible absorption spectrum characteristic of other members of the amidohydrolase superfamily replaced with cobalt. PMID:16885454

  8. Mg2+ binding and structural stability of mature and in vitro synthesized unmodified Escherichia coli tRNAPhe.

    PubMed Central

    Serebrov, V; Vassilenko, K; Kholod, N; Gross, H J; Kisselev, L

    1998-01-01

    Mature tRNAPhe from Escherichia coli and the transcript of its gene lacking modified nucleotides were compared by a variety of physical techniques. Melting experiments revealed that at a low Mg2+level the transcript was partially denatured, while the mature tRNA possessed intact tertiary interactions. Mg2+binding to both tRNAs was studied by CD and UV techniques as well as by using the Mg2+-sensitive fluorescence indicator, 8-hydroxyquinoline 5-sulfonic acid. Both tRNA forms exhibited a single strong Mg2+-binding site, its dissociation constant was 10-fold higher for the transcript. Conformational changes in response to Mg2+ addition measured by CD and UV spectrometry revealed no difference for the estimated binding cooperativity and strong differences for affinities of Mg2+-binding sites for the two tRNA forms. Conformational transitions in mature and in in vitro synthesized tRNA required the binding of two Mg2+ ions per molecule and therefore should be associated not only with a single strong binding site. The Mg2+ dependence of Stokes radii measured by gel-filtration revealed insignificant differences between the overall sizes of the two tRNA forms at physiological Mg2+ levels (>1 mM). Taken together, these results suggest that modified nucleotides stabilize tertiary interactions and increase the structure stability without affecting the mechanism of Mg2+binding and overall folding of the tRNA molecule. This conclusion is supported by the known biological activity of the E. coli tRNAPhe gene transcript. PMID:9592160

  9. Inactivation of botulinum and tetanus toxins by chelators.

    PubMed

    Bhattacharyya, S D; Sugiyama, H

    1989-10-01

    Purified type A botulinum toxin of about 10(6) mouse 50% lethal doses per ml was greater than 99.9% inactivated when incubated at pH 7.4 for 30 min at 37 degrees C in 20 mM 1,10-phenanthroline (PTL) or 2,2'-dipyridyl (DPD) and was 96% inactivated when incubated in 70 mM 8-hydroxyquinoline-5-sulfonic acid (HQL), but was not affected when incubated in 200 mM EDTA. When used as a representative of the chelating agents, PTL inactivated greater than or equal to 99.9% of toxicity in the culture filtrate of C. botulinum type A, B, and E strains. Highly purified tetanus toxin at 2.5 x 10(5) 50% lethal doses per ml lost all toxicity in 40 mM PTL or 150 mM DPD but was not detectably affected by 100 mM HQL (the highest concentration possible). Toxin inactivation by 20 mM PTL was completely blocked when the PTL was prereacted with an equimolar amount of Zn2+ and significantly reduced when it was preincubated with one-third its molar amount of Fe2+. DPD at 20 mM had little toxin-inactivating potency when preincubated with an equimolar amount of Zn2+ and only some of this potency when preincubated with an equimolar amount of Fe2+. Toxicity was not recovered by adding Zn2+ or Fe2+ to PTL-treated toxin. Neutron activation analysis of type A toxin showed that for each toxin molecule present, there was 1 atom of Fe, 0.4 atom of Zn, and 22 to 55 atoms each of Ca and Mg. The biological activity of botulinum toxin seems to depend on a metal component, which is likely to be Fe.

  10. Bioavailability of iron sensed by a phytoplanktonic Fe-bioreporter.

    PubMed

    Hassler, Christel S; Twiss, Michael R

    2006-04-15

    This study describes a short-term (12 h) evaluation of iron (Fe) bioavailability to an Fe-dependent cyanobacterial bioreporter derived from Synechococcus PCC 7942. Several synthetic ligands with variable conditional stability constants for Fe(lll) (K* of 10(19.8) to 10(30.9)), in addition to several defined natural Fe-binding ligands and a fulvic acid of aquatic origin (Suwannee River), were used to elucidate the forms of Fe that are discerned by this phytoplanktonic microbe: Fe-HEBD (log conditional stability constant, K*, = 28.1, HEBD = N,N'-di(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid monohydrochloride hydrate), Fe-HDFB (K* = 30.9, DFB = desferroxamine B), Fe-ferrichrome (K* = 23.2), Fe-DTPA (K* = 21.1, DTPA = diethylenetrinitrilopentaacetic acid), Fe-(8HQS)2 (K* = 20.4, 8HQS = 8-hydroxyquinoline-5-sulfonic acid), Fe-CDTA (K* = 19.8, CDTA = trans-1,2-cyclohexylenedinitrilotetraacetic acid), and Fe-EDTA (K* = 19.2). Iron bioavailability sensed by the bioreporter was related to diffusion limitation and activity of high-affinity transporters rather than by siderophore secretion. Iron complexed with a K* < 23.2 contributes to the bioavailable pool; bioavailability could be explained by disjunctive ligand exchange considerations and fully, partially, and nonbioavailable complexes could be distinguished according to their conditional stability constant. The use of Fe-bioreporters provides a relevant measurement of bioavailability to an important group of primary producers in freshwaters (cyanobacteria) and is thus a promising technique for understanding Fe cycling in aquatic systems.

  11. A Novel Method for Dissolved Phosphorus Analysis

    NASA Astrophysics Data System (ADS)

    Berry, J. M.; Spiese, C. E.

    2012-12-01

    High phosphorus loading is a major problem in the Great Lakes watershed. Phosphate enters waterways via both point and non-point sources (e.g., runoff, tile drainage, etc.), promoting eutrophication, and ultimately leading to algal blooms, hypoxia and loss of aquatic life. Quantification of phosphorus loading is typically done using the molybdenum blue method, which is known to have significant drawbacks. The molybdenum blue method requires strict control on time, involves toxic reagents that have limited shelf-life, and is generally unable to accurately measure sub-micromolar concentrations. This study aims to develop a novel reagent that will overcome many of these problems. Ethanolic europium(III) chloride and 8-hydroxyquinoline-5-sulfonic acid (hqs) were combined to form the bis-hqs complex (Eu-hqs). Eu-hqs was synthesized as the dipotassium salt via a simple one-pot procedure. This complex was found to be highly fluorescent (λex = 360 nm, λem = 510 nm) and exhibited a linear response upon addition of monohydrogen phosphate. The linear response ranged from 0.5 - 25 μM HPO42- (15.5 - 775 μg P L-1). It was also determined that Eu-hqs formed a 1:1 complex with phosphate. Maximum fluorescence was found at a pH of 8.50, and few interferences from other ions were found. Shelf-life of the reagent was at least one month, twice as long as most of the molybdenum blue reagent formulations. In the future, field tests will be undertaken in local rivers, lakes, and wetlands to determine the applicability of the complex to real-world analysis.

  12. Identification and characterization of a metalloprotease activity from Helicobacter pylori.

    PubMed

    Windle, H J; Kelleher, D

    1997-08-01

    Helicobacter pylori produces a metalloprotease with a native molecular size of approximately 200 kDa, as determined by size-exclusion chromatography. Subcellular distribution studies demonstrated that the activity was associated with the outer membrane fraction of the bacterium. In addition, the protease was secreted by the bacterium when grown in liquid culture. The enzyme activity was measured by hydrolysis of azocasein and biotinylated casein and exhibited optimal caseinolytic activity at pH 8.0 (37 degrees C). The activity was inhibited by EDTA, 1,10-phenanthroline, phosphoramidon, pyridine-2,6-dicarboxylic acid, and 8-hydroxyquinoline-5-sulfonic acid (HQSA). Inhibition by HQSA was reversed by zinc, whereas inhibition due to EDTA was reversed by excess calcium, thus indicating that the enzyme was a zinc-dependent, calcium-stabilized endoproteinase. Furthermore, titration with Zn2+ of a desalted, active-site zinc-chelated preparation of the protease demonstrated that Zn2+ was essential for activity. Leupeptin, phenylmethylsulfonyl fluoride, E-64, pepstatin A, dithiothreitol, and 2-mercaptoethanol had no effect on enzymatic activity. Addition of Ca2+ or Mg2+ to the incubation medium resulted in approximately a twofold stimulation of the azocaseinolytic activity of the enzyme. The protease was stably expressed since it was active even after repeated subculture of the bacterium. Bovine serum albumin, hide powder azure, and elastin-Congo red remained intact even after prolonged exposure to the enzyme. The surface expression of this metalloprotease activity raises the possibility that this enzyme may be involved in the proteolysis of a variety of host proteins in vivo and thereby contributes to gastric pathology.

  13. TrzN from Arthrobacter aurescens TC1 Is a zinc amidohydrolase.

    PubMed

    Shapir, Nir; Pedersen, Charlotte; Gil, Omer; Strong, Lisa; Seffernick, Jennifer; Sadowsky, Michael J; Wackett, Lawrence P

    2006-08-01

    TrzN, the broad-specificity triazine hydrolase from Arthrobacter and Nocardioides spp., is reportedly in the amidohydrolase superfamily of metalloenzymes, but previous studies suggested that a metal was not required for activity. To help resolve that conundrum, a double chaperone expression system was used to produce multimilligram quantities of functionally folded, recombinant TrzN. The TrzN obtained from Escherichia coli (trzN) cells cultured with increasing zinc in the growth medium showed corresponding increases in specific activity, and enzyme obtained from cells grown with 500 muM zinc showed maximum activity. Recombinant TrzN contained 1 mole of Zn per mole of TrzN subunit. Maximally active TrzN was not affected by supplementation with most metals nor by EDTA, consistent with previous observations (E. Topp, W. M. Mulbry, H. Zhu, S. M. Nour, and D. Cuppels, Appl. Environ. Microbiol. 66:3134-3141, 2000) which had led to the conclusion that TrzN is not a metalloenzyme. Fully active native TrzN showed a loss of greater than 90% of enzyme activity and bound zinc when treated with the metal chelator 8-hydroxyquinoline-5-sulfonic acid. While exogenously added zinc or cobalt restored activity to metal-depleted TrzN, cobalt supported lower activity than did zinc. Iron, manganese, nickel, and copper did not support TrzN activity. Both Zn- and Co-TrzN showed different relative activities with different s-triazine substrates. Co-TrzN showed a visible absorption spectrum characteristic of other members of the amidohydrolase superfamily replaced with cobalt.

  14. Zinc is essential for binding of p56(lck) to CD4 and CD8alpha.

    PubMed

    Lin, R S; Rodriguez, C; Veillette, A; Lodish, H F

    1998-12-01

    Binding of the protein tyrosine kinase p56(lck) to T-cell co-receptors CD4 and CD8alpha is necessary for T-lymphocyte development and activation. Association of p56(lck) with CD4 requires two conserved cysteine residues in the cytosolic domain of CD4 and two in the amino terminus of p56(lck), consistent with the notion that these four residues coordinate a single metal atom (1-5). Here we demonstrate that Zn2+ is essential for complex formation. In an in vitro binding reaction, Zn2+ mediates p56(lck) association with a glutathione S-transferase (GST) fusion protein containing the cytosolic domains of CD4 or CD8alpha; no other metals tested support binding. Treatment of preformed GST-CD4.p56(lck) dimers with the Zn2+ chelators 1,10-O-phenanthroline or 8-hydroxyquinoline-5-sulfonic acid results in dissociation of GST-CD4 from p56(lck), consistent with the finding of Huse et al. (5) that Zn2+ is contained within similar complexes. Furthermore, we show that, within live cells, CD4.p56(lck) and CD8alpha.p56(lck) interactions occur in a zinc-dependent fashion. Specifically, pretreatment of the human Jurkat T-cell line with membrane permeable zinc chelators disrupts CD4.p56(lck) complexes, and treatment of COS cells co-expressing CD8alpha and p56(lck) with such chelators likewise leads to dissociation of CD8alpha.p56(lck) complexes. CD4. p56(lck) and CD8alpha.p56(lck) represent the first examples of intracellular proteins that require zinc as a bridge for heterodimerization.

  15. Angiotensin I-converting enzyme inhibitors potentiate bradykinin's inotropic effects independently of blocking its inactivation.

    PubMed

    Minshall, R D; Erdös, E G; Vogel, S M

    1997-08-01

    The positive inotropic effects of bradykinin (BK) and 2 analogs resistant to angiotensin I-converting enzyme (ACE) were potentiated on isolated guinea pig atrial preparations by enalaprilat. The stable BK analogs, dextran-BK and [Hyp3-Tyr(Me)8]-BK, were as active as BK. Pretreatment for 5 min with enalaprilat augmented the maximal positive inotropic effect of [Hyp3-Tyr(Me)8]-BK 2.8-fold, from 19% to 53% and that of BK from 28% to 42% over baseline; inotropic responses to dextran-BK (1 microM) were similarly increased. The activity of atrial ACE, a zinc-requiring enzyme, was completely inhibited by 8-hydroxyquinoline-5-sulfonic acid (QSA, 10 mM), which raised the maximal inotropic effect of BK to 39% above baseline. This value rose to 67% when in addition to QSA, 1 microM enalaprilat was added; enalaprilat thus, potentiated the effects of BK independently of enzyme inhibition. The positive inotropic effects to BK and its analogs decline with time in the presence of these agonists. After 10 min of exposure, the response to 1 microM [Hyp3-Tyr(Me)8]-BK decreased to about half, and after 20 min, to 0. Enalaprilat, when present in the tissue bath, prevented the decline in inotropy; even after tachyphylaxis occurred, it reversed this decrease in activity when added. The effects of 1 microM [Hyp3-Tyr(Me)8]-BK, in the absence or presence of enalaprilat, were abolished by the BK B2 receptor antagonist icatibant (0.75 microM). The results indicate that ACE inhibitors, by potentiating the BK effects and blocking BK B2-receptor desensitization, may contribute to the beneficial cardiac effects of BK independently of blocking its inactivation.

  16. Anions Influence the Relaxation Dynamics of Mono-μ3-OH-Capped Triangular Dysprosium Aggregates.

    PubMed

    Zhang, Li; Zhang, Peng; Zhao, Lang; Wu, Jianfeng; Guo, Mei; Tang, Jinkui

    2015-06-01

    A family of four Dy3 triangular circular helicates, namely, [Dy3(HL)3(μ3-OH)(CH3OH)2(H2O)4]Cl1.5(OH)0.5·0.5H2O (1), [Dy3(HL)3(μ3-OH)(CH3OH)3(H2O)2Cl]Cl·CH3OH (2), [Dy3(HL)3(μ3-OH)(CH3OH)3(H2O)2(NO3)](NO3) (3), and [Dy3(HL)3(μ3-OH)(CH3OH)4(ClO4)](ClO4) (4), were assembled by the reaction of a new acylhydrazone ligand H3L [(3-hydroxy)-N'-((8-hydroxyquinolin-2-yl)methylene)picolinohydrazide] with different dysprosium(III) salts. These compounds represent the first examples of μ-Oacylhydrazone-bridged triangular Dy3 SMMs reported to date. Alternating-current magnetic susceptibility measurements revealed that compounds 1 and 2 show typical SMM behavior with the occurrence of multiple relaxation processes, whereas frequency-dependent relaxation signals without χ″ peaks were observed in 3 and 4 under zero dc field. Such distinct dynamic behaviors are attributed to the different sizes of the terminal coordination solvent/anions (H2O, Cl(-), NO3(-), and ClO4(-) for 1-4, respectively) at the Dy3 site. Here, similar deviations from the ideal monocapped square-antiprismatic (C4v) geometry defined by SHAPE software were observed around local Dy centers in 1 and 2, whereas the situation was completely different in 3 and 4 as a result of the presence of relatively large anions in the limited space defined by three intercrossing rigid hydrazone ligands. PMID:25984586

  17. A series of dinuclear Dy(iii) complexes bridged by 2-methyl-8-hydroxylquinoline: replacement on the periphery coordinated β-diketonate terminal leads to different single-molecule magnetic properties.

    PubMed

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

    2016-03-01

    A series of HMq-bridged dinuclear dysprosium complexes, namely, [Dy(acac)2(CH3OH)]2(μ-HMq)2 (1), [Dy(DBM)2]2(μ-HMq)2(n-C6H14) (2), [Dy(hmac)2]2(μ-HMq)2 (3) and [Dy(hfac)3]2(μ-HMq)2 (4) (HMq = 2-methyl-8-hydroxyquinoline, acac = acetylacetone, DBM = dibenzoylmethane, hmac = hexamethylacetylacetonate and hfac = hexafluoroacetylacetonate), were structurally and magnetically characterized. X-ray crystallographic analyses of the structures reveal that HMq serves as the effective bridge to link two Dy(III) centers by means of the phenoxyl oxygen and nitrogen atoms and the periphery β-diketonate ligands complete the coordination sphere by bidentate oxygen atoms. The different substituents on the β-diketonate terminal lead to different coordination models mostly due to the steric hindrance of these substituents, and the electron-withdrawing or donating effects likely influence the strength of the ligand fields and the Dy(III) ion anisotropy. Measurements of alternating-current (ac) susceptibility on complexes 1-4 reveal that complexes 3 and 4 display significant zero-field single-molecule magnetic (SMM) behavior with barrier energy Ueff/kB = 14.8 K, τ0 = 1.8 × 10(-5) s and Ueff/kB = 9.2 K, τ0 = 1.7 × 10(-5) s, respectively, whereas 1 and 2 exhibit field-induced SMM behavior, and these differences are attributed to the alteration on the periphery β-diketonate ligands. Their distinct slow magnetic relaxation behaviors were related to their different individual Dy(III) ion magnetic anisotropy and intramolecular coupling, which were confirmed by ab initio calculations. PMID:26905041

  18. The effects of ultra-thin cerium fluoride film as the anode buffer layer on the electrical characteristics of organic light emitting diodes

    NASA Astrophysics Data System (ADS)

    Lu, Hsin-Wei; Tsai, Cheng-Che; Hong, Cheng-Shong; Kao, Po-Ching; Juang, Yung-Der; Chu, Sheng-Yuan

    2016-11-01

    In this study, the efficiency of organic light-emitting diodes (OLEDs) was enhanced by depositing a CeF3film as an ultra-thin buffer layer between the indium tin oxide (ITO) electrode and α-naphthylphenylbiphenyldiamine (NPB) hole transport layer, with the structure configuration ITO/CeF3 (0.5, 1, and 1.5 nm)/α-naphthylphenylbiphenyl diamine (NPB) (40 nm)/tris(8-hydroxyquinoline) aluminum (Alq3) (60 nm)/lithium fluoride (LiF) (1 nm)/Al (150 nm). The enhancement mechanism was systematically investigated via several approaches. The X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy results revealed the formation of the UV-ozone treated CeF3 film. The work function increased from 4.8 eV (standard ITO electrode) to 5.22 eV (0.5-nm-thick UV-ozone treated CeF3 film deposited on the ITO electrode). The surface roughness of the UV-ozone treated CeF3 film was smoother than that of the standard ITO electrode. Further, the UV-ozone treated CeF3 film increased both the surface energy and polarity, as determined from contact angle measurements. In addition, admittance spectroscopy measurements showed an increased capacitance and conductance of the OLEDs. Accordingly, the turn-on voltage decreased from 4.2 V to 3.6 V at 1 mA/cm2, the luminance increased from 7588 cd/m2 to 24760 cd/m2, and the current efficiency increased from 3.2 cd/A to 3.8 cd/A when the 0.5-nm-thick UV-ozone treated CeF3 film was inserted into the OLEDs.

  19. SG-HQ2 inhibits mast cell-mediated allergic inflammation through suppression of histamine release and pro-inflammatory cytokines.

    PubMed

    Je, In-Gyu; Kim, Hui-Hun; Park, Pil-Hoon; Kwon, Taeg Kyu; Seo, Seung-Yong; Shin, Tae-Yong; Kim, Sang-Hyun

    2015-05-01

    In this study, we investigated the effect of 3,4,5-trihydroxy-N-(8-hydroxyquinolin-2-yl)benzamide) (SG-HQ2), a synthetic analogue of gallic acid (3,4,5-trihydroxybenzoic acid), on the mast cell-mediated allergic inflammation and the possible mechanism of action. Mast cells play major roles in immunoglobulin E-mediated allergic responses by the release of histamine, lipid-derived mediators, and pro-inflammatory cytokines. We previously reported the potential effects of gallic acid using allergic inflammation models. For incremental research, we synthesized the SG-HQ2 by the modification of functional groups from gallic acid. SG-HQ2 attenuated histamine release by the reduction of intracellular calcium in human mast cells and primary peritoneal mast cells. The inhibitory efficacy of SG-HQ2 was similar with gallic acid. Enhanced expression of pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin-1β, interleukin-4, and interleukin-6 in activated mast cells was significantly diminished by SG-HQ2 100 times lower concentration of gallic acid. This inhibitory effect was mediated by the reduction of nuclear factor-κB. In animal models, SG-HQ2 inhibited compound 48/80-induced serum histamine release and immunoglobulin E-mediated local allergic reaction, passive cutaneous anaphylaxis. Our results indicate that SG-HQ2, an analogue of gallic acid, might be a possible therapeutic candidate for mast cell-mediated allergic inflammatory diseases through suppression of histamine release and pro-inflammatory cytokines.

  20. Oxidation of hydroxylamine by cytochrome P-460 of the obligate methylotroph Methylococcus capsulatus Bath.

    PubMed Central

    Zahn, J A; Duncan, C; DiSpirito, A A

    1994-01-01

    An enzyme capable of the oxidation of hydroxylamine to nitrite was isolated from the obligate methylotroph Methylococcus capsulatus Bath. The absorption spectra in cell extracts, electron paramagnetic resonance spectra, molecular weight, covalent attachment of heme group to polypeptide, and enzymatic activities suggest that the enzyme is similar to cytochrome P-460, a novel iron-containing protein previously observed only in Nitrosomonas europaea. The native and subunit molecular masses of the M. capsulatus Bath protein were 38,900 and 16,390 Da, respectively; the isoelectric point was 6.98. The enzyme has approximately one iron and one copper atom per subunit. The electron paramagnetic resonance spectrum of the protein showed evidence for a high-spin ferric heme. In contrast to the enzyme from N. europaea, a 13-nm blue shift in the soret band of the ferrocytochrome (463 nm in cell extracts to 450 nm in the final sample) occurred during purification. The amino acid composition and N-terminal amino acid sequence of the enzyme from M. capsulatus Bath was similar but not identical to those of cytochrome P-460 of N. europaea. In cell extracts, the identity of the biological electron acceptor is as yet unestablished. Cytochrome c-555 is able to accept electrons from cytochrome P-460, although the purified enzyme required phenazine methosulfate for maximum hydroxylamine oxidation activity (specific activity, 366 mol of O2 per s per mol of enzyme). Hydroxylamine oxidation rates were stimulated approximately 2-fold by 1 mM cyanide and 1.5-fold by 0.1 mM 8-hydroxyquinoline. Images PMID:7928947

  1. Self-assembled systems of water soluble metal 8-hydroxyquinolates with surfactants and conjugated polyelectrolytes.

    PubMed

    Burrows, Hugh D; Costa, Telma; Ramos, M Luisa; Valente, Artur J M; Stewart, Beverly; Justino, Licinia L G; Almeida, Aline I A; Catarina, Nathanny Lessa; Mallavia, Ricardo; Knaapila, Matti

    2016-06-22

    We have studied the interaction of 8-hydroxyquinoline-5-sulfonate (8-HQS) with the metal ions Al(iii) and Zn(ii) in aqueous solution in the presence of tetraalkylammonium surfactants using UV/vis absorption, fluorescence, NMR spectroscopy and electrical conductivity measurements, complemented by DFT calculations and molecular dynamics (MD) simulations. Under appropriate conditions, complexes between 8-HQS and metal ions form rapidly, and have similar electronic, spectroscopic and photophysical properties to the corresponding metal quinolates, such as Alq3. These interact with the cationic surfactants, leading to marked increases in fluorescence intensity. However, significant differences are seen in the behavior of the two metal ions. With aluminium, a stable [Al(8-QS)3](3-) anion is formed, and interacts, predominantly through electrostatic interactions, with the surfactant, without disrupting the metal ion coordination sphere. In contrast, with Zn(ii), there is a competition between the metal ion and surfactants in the interaction with 8-HQS, although the [Zn(8-QS)2(H2O)2](2-) species is stable at appropriate pH and surfactant concentration. The studies are extended to systems with the conjugated polyelectrolyte (CPE) poly-(9,9-bis(6-N,N,N-trimethylammonium)hexyl)-fluorene-phenylene bromide (HTMA-PFP), which has a similar alkylammonium chain to the surfactants. Mixing metal salt, 8-HQS and HTMA-PFP in the presence of a nonionic surfactant leads to the formation of a metal complex/CPE supramolecular assembly between the conjugated polyelectrolyte and the metal/8-HQS complex, as demonstrated by electronic energy transfer. The potential of these systems in sensing, light harvesting, and electron injection/transport layers in organic semiconductor devices is discussed. PMID:26817700

  2. Supramolecular structure and substituents effect on the spectral studies of dioxouranium(VI) azodyes complexes

    NASA Astrophysics Data System (ADS)

    Diab, M. A.; El-Bindary, A. A.; El-Sonbati, A. Z.; Salem, O. L.

    2012-01-01

    The synthesis of several coordination azo compounds of dioxouranium(VI) heterochelates with bidentate azo compounds derived from 4-alkylphenylazo-5-sulfo-8-hydroxyquinoline (HL n) ligands, are described. The ligands and structural composition of azo complexes were confirmed and characterized by various physico-chemical techniques. The bonding sites of the azo compounds are deduced from IR and 1H NMR spectra and the ligands were found to bond to the UO22+ ion in a bidentate fashion. The ligands obtained contain N dbnd N and phenolic functional groups in different positions with respect to the quinoline group. IR spectra show that the azo compounds (HL n) acts as a monobasic bidentate ligand by coordinating via the azo nitrogen atom of azodye ( sbnd N dbnd N sbnd ) and oxygen atom of the phenolic group forming thereby a six-membered chelating ring and concomitant formation of an intramolecular hydrogen bond. The υ3 frequency of UO22+ has been shown to be an excellent molecular probe for studying the coordinating power of the ligands. The values of υ3 of the prepared complexes containing UO22+ were successfully used to calculate the force constant, FUO (1n 10 -8 N/Å) and the bond length RUO (in Å) of the U sbnd O bond. A strategy based upon both theoretical and experimental investigations has been adopted. The theoretical aspects are described in terms of the well-known theory of 5d-4f transitions. Wilson's, matrix method, Badger's formula, and Jones and El-Sonbati equations were used to calculate the U sbnd O bond distances from the values of the stretching and interaction force constants. The most probable correlation between U sbnd O force constant to U sbnd O bond distance were satisfactorily discussed in term of Badger's rule and the equations suggested by Jones and El-Sonbati. The effect of Hamette's constant is also discussed.

  3. Utility of solid-phase spectrophotometry to determine trace amounts of zinc in environmental and biological samples.

    PubMed

    Amin, Alaa S

    2011-11-15

    A solid-phase spectrophotometric analysis has been proposed for preconcentration and determination of Zn(II) in real samples. The procedure is based on sorption of zinc(II) as 5-(2-benzothiazolylazo)-8-hydroxyquinoline (BTAHQ) complex on dextran-type anion-exchange gel (Sephadex DEAE A-25). The influences of the analytical parameters, including pH of the aqueous solution, amounts of BTAHQ, and sample volume, were investigated. The absorbance of the gel at 675 and 750 nm, packed in a 1.0-mm cell, was measured directly. The molar absorptivities were found to be 2.50×10(7) and 9.55×10(7)L mol(-1) cm(-1) for 500 and 1000 ml, respectively. Calibration was linear over the range of 0.05-1.10 μg L(-1) with a relative standard deviation of less than 1.60% (n=10). The detection and quantification limits of the 500-ml sample method were 12 and 40 ng L(-1) on using 50 mg. For the 1000-ml sample, the detection and quantification limits were 7.5 and 25 ng L(-1) using a 50-mg exchanger. Increasing the sample volume can enhance sensitivity. No considerable interferences were observed from other investigated anions and cations on the Zn(II) determination. The proposed method was applied to determine zinc in environmental samples, including natural water, food, certified reference materials, meat, and biological samples, comparing the results simultaneously with those obtained using a flame atomic absorption spectrophotometer, whereby the validity of the method was tested. PMID:21820999

  4. Alginate microbead-encapsulated silver complexes for selective delivery of broad-spectrum silver-based microbicides.

    PubMed

    Damelin, Leonard H; Fernandes, Manuel A; Tiemessen, Caroline T

    2015-10-01

    In sub-Saharan Africa, human immunodeficiency virus (HIV) infections are predominantly acquired via heterosexual contact, and women are at greatest risk of being infected. This region also has the highest rates of sexually transmitted infections (STIs) per capita worldwide; STIs are strongly associated with increased HIV transmission. Therefore, there is an urgent requirement for microbicides that are active against HIV and STIs. Silver compounds exhibit broad antimicrobial activity, making them potentially ideal broad-spectrum microbicides. However, for silver compounds to be effective microbicides, they must be active within seminal fluid and the delivery vehicle used must protect the silver microbicide from vaginal fluid components but selectively release it during intercourse and/or following ejaculation. In this study, silver complexes were synthesised from the ligands saccharin, benzimidazole and 8-hydroxyquinoline and their microbicidal activity was assessed. We show that a silver saccharinate-benzimidazole complex (AgSB) exhibited activity against HIV-1, herpes simplex virus type 2 (HSV-2) and Neisseria gonorrhoeae at concentrations significantly below LD(50) levels for the vaginal mucosal cell line SiHa. Furthermore, we show that alginate microbeads are stable in vaginal fluid simulant but rapidly dissolve in seminal fluid simulant. Finally, we have established that microbead-encapsulated AgSB, dissolved in seminal fluid simulant, is active against the above pathogens, albeit at higher concentrations for HIV-1. This research therefore highlights, for the first time, the potential use of silver complexes encapsulated in alginate microbeads as a novel system for the delivery and selective release of broad-spectrum silver-based microbicides within the vaginal milieu during sexual intercourse/after ejaculation.

  5. X-rays sensing properties of MEH-PPV, Alq₃ and additive components: a new organic dosimeter as a candidate for minimizing the risk of accidents of patients undergoing radiation oncology.

    PubMed

    Schimitberger, T; Ferreira, G R; Akcelrud, L C; Saraiva, M F; Bianchi, R F

    2013-01-01

    In this paper, we report our experimental design in searching a smart and easy-to-read dosimeter used to detect 6 MV X-rays for improving patient safety in radiation oncology. The device was based on an organic emissive solutions of poly(2-methoxy-5(2'-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV), aluminum-tris-(8-hydroxyquinoline) (Alq₃) and additive components which were characterized by UV-Vis absorption, photoluminescence and CIE color coordinate diagram. The optical properties of MEH-PPV/Alq₃ solutions have been examined as function of radiation dose over the range of 0-100 Gy. It has shown that MEH-PPV/Alq₃ solutions are specifically sensitive to X-rays, since the effect of radiation on this organic system is strongly correlated with the efficient spectral overlap between Alq₃ emission and the absorption of degraded MEH-PPV, which alters the color and photoemission of MEH-PPV/Alq₃ mixtures from red to yellow, and then to green. The rate of this change is more sensitive when MEH-PPV/Alq₃ is irradiated in the presence of benzoyl peroxide than when in the presence of hindered phenolic stabilizers, respectively, an accelerator and an inhibitor to activate or inhibit free radical formation. This gives rise to optimize the response curve of the dosimeter. It is clear from the experimental results that organic emissive semiconductors have potential to be used as dedicated and low-cost dosimeters to provide an independent check of beam output of a linear accelerator and therefore to give patients the opportunity to have information on the dose prescription or equipment-related problems a few minutes before being exposed to radiation.

  6. Alginate microbead-encapsulated silver complexes for selective delivery of broad-spectrum silver-based microbicides.

    PubMed

    Damelin, Leonard H; Fernandes, Manuel A; Tiemessen, Caroline T

    2015-10-01

    In sub-Saharan Africa, human immunodeficiency virus (HIV) infections are predominantly acquired via heterosexual contact, and women are at greatest risk of being infected. This region also has the highest rates of sexually transmitted infections (STIs) per capita worldwide; STIs are strongly associated with increased HIV transmission. Therefore, there is an urgent requirement for microbicides that are active against HIV and STIs. Silver compounds exhibit broad antimicrobial activity, making them potentially ideal broad-spectrum microbicides. However, for silver compounds to be effective microbicides, they must be active within seminal fluid and the delivery vehicle used must protect the silver microbicide from vaginal fluid components but selectively release it during intercourse and/or following ejaculation. In this study, silver complexes were synthesised from the ligands saccharin, benzimidazole and 8-hydroxyquinoline and their microbicidal activity was assessed. We show that a silver saccharinate-benzimidazole complex (AgSB) exhibited activity against HIV-1, herpes simplex virus type 2 (HSV-2) and Neisseria gonorrhoeae at concentrations significantly below LD(50) levels for the vaginal mucosal cell line SiHa. Furthermore, we show that alginate microbeads are stable in vaginal fluid simulant but rapidly dissolve in seminal fluid simulant. Finally, we have established that microbead-encapsulated AgSB, dissolved in seminal fluid simulant, is active against the above pathogens, albeit at higher concentrations for HIV-1. This research therefore highlights, for the first time, the potential use of silver complexes encapsulated in alginate microbeads as a novel system for the delivery and selective release of broad-spectrum silver-based microbicides within the vaginal milieu during sexual intercourse/after ejaculation. PMID:26184337

  7. Hydroxyquinoline derived vanadium(IV and V) and copper(II) complexes as potential anti-tuberculosis and anti-tumor agents.

    PubMed

    Correia, Isabel; Adão, Pedro; Roy, Somnath; Wahba, Mohamed; Matos, Cristina; Maurya, Mannar R; Marques, Fernanda; Pavan, Fernando R; Leite, Clarice Q F; Avecilla, Fernando; Costa Pessoa, João

    2014-12-01

    Several mixed ligand vanadium and copper complexes were synthesized containing 8-hydroxyquinoline (8HQ) and a ligand such as picolinato (pic(-)), dipicolinato (dipic(2-)) or a Schiff base. The complexes were characterized by spectroscopic techniques and by single-crystal X-ray diffraction in the case of [V(V)O(L-pheolnaph-im)(5-Cl-8HQ)] and [V(V)O(OMe)(8HQ)2], which evidenced the distorted octahedral geometry of the complexes. The electronic absorption data showed the presence of strong ligand to metal charge transfer bands, significant solvent effects, and methoxido species in methanol, which was further confirmed by (51)V-NMR spectroscopy. The structures of [Cu(II)(dipic)(8HQ)]Na and [V(IV)O(pic)(8HQ)] were confirmed by EPR spectroscopy, showing only one species in solution. The biological activity of the compounds was assessed through the minimal inhibitory concentration (MIC) of the compounds against Mycobacterium tuberculosis (Mtb) and the cytotoxic activity against the cisplatin sensitive/resistant ovarian cells A2780/A2780cisR and the non-tumorigenic HEK cells (IC50 values). Almost all tested vanadium complexes were very active against Mtb and the MICs were comparable to, or better than, the MICs of drugs, such as streptomycin. The activity of the complexes against the A2780 cell line was dependent on incubation time presenting IC50 values in the 3-14 μM (at 48 h) range. In these conditions, the complexes were significantly (*P<0.05-**P<0.001) more active than cisplatin (22 μM), in the A2780 cells and even surpassing its activity in the cisplatin-resistant cells A2780cisR (2.4-8 μM vs. 75.4; **P<0.001). In the non-tumorigenic HEK cells poor selectivity toward cancer cells for most of the complexes was observed, as well as for cisplatin.

  8. Synthesis, magnetic, spectral, and antimicrobial studies of Cu(II), Ni(II) Co(II), Fe(III), and UO 2(II) complexes of a new Schiff base hydrazone derived from 7-chloro-4-hydrazinoquinoline

    NASA Astrophysics Data System (ADS)

    El-Behery, Mostafa; El-Twigry, Haifaa

    2007-01-01

    A new hydrazone ligand, HL, was prepared by the reaction of 7-chloro-4-hydrazinoquinoline with o-hydroxybenzaldehyde. The ligand behaves as monoprotic bidentate. This was accounted for as the ligand contains a phenolic group and its hydrogen atom is reluctant to be replaced by a metal ion. The ligand reacted with Cu(II), Ni(II), Co(II), Fe(III), and UO 2(II) ions to yield mononuclear complexes. In the case of Fe(III) ion two complexes, mono- and binuclear complexes, were obtained in the absence and presence of LiOH, respectively. Also, mixed ligand complexes were obtained from the reaction of the metal cations Cu(II), Ni(II) and Fe(III) with the ligand (HL) and 8-hydroxyquinoline (8-OHqu) in the presence of LiOH, in the molar ratio 1:1:1:1. It is clear that 8-OHqu behaves as monoprotic bidentate ligand in such mixed ligand complexes. The ligand, HL, and its metal complexes were characterized by elemental analyses, IR, UV-vis, mass, and 1H NMR spectra, as well as magnetic moment, conductance measurements, and thermal analyses. All complexes have octahedral configurations except Cu(II) complex which has an extra square-planar geometry, while Ni(II) mixed complex has also formed a tetrahedral configuration and UO 2(II) complex which formed a favorable pentagonal biprymidial geometry. Magnetic moment of the binuclear Fe(III) complex is quite low compared to calculated value for two iron ions complex and thus shows antiferromagnetic interactions between the two adjacent ferric ions. The HL and metal complexes were tested against one stain Gram positive bacteria ( Staphylococcus aureus), Gram negative bacteria ( Escherichia coli), and fungi ( Candida albicans). The tested compounds exhibited higher antibacterial acivities.

  9. A new dispersive liquid-liquid microextraction using ionic liquid based microemulsion coupled with cloud point extraction for determination of copper in serum and water samples.

    PubMed

    Arain, Salma Aslam; Kazi, Tasneem Gul; Afridi, Hassan Imran; Arain, Mariam Shahzadi; Panhwar, Abdul Haleem; Khan, Naeemullah; Baig, Jameel Ahmed; Shah, Faheem

    2016-04-01

    A simple and rapid dispersive liquid-liquid microextraction procedure based on ionic liquid assisted microemulsion (IL-µE-DLLME) combined with cloud point extraction has been developed for preconcentration copper (Cu(2+)) in drinking water and serum samples of adolescent female hepatitits C (HCV) patients. In this method a ternary system was developed to form microemulsion (µE) by phase inversion method (PIM), using ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) and nonionic surfactant, TX-100 (as a stabilizer in aqueous media). The Ionic liquid microemulsion (IL-µE) was evaluated through visual assessment, optical light microscope and spectrophotometrically. The Cu(2+) in real water and aqueous acid digested serum samples were complexed with 8-hydroxyquinoline (oxine) and extracted into IL-µE medium. The phase separation of stable IL-µE was carried out by the micellar cloud point extraction approach. The influence of of different parameters such as pH, oxine concentration, centrifugation time and rate were investigated. At optimized experimental conditions, the limit of detection and enhancement factor were found to be 0.132 µg/L and 70 respectively, with relative standard deviation <5%. In order to validate the developed method, certified reference materials (SLRS-4 Riverine water) and human serum (Sero-M10181) were analyzed. The resulting data indicated a non-significant difference in obtained and certified values of Cu(2+). The developed procedure was successfully applied for the preconcentration and determination of trace levels of Cu(2+) in environmental and biological samples. PMID:26761783

  10. SG-HQ2 inhibits mast cell-mediated allergic inflammation through suppression of histamine release and pro-inflammatory cytokines

    PubMed Central

    Je, In-Gyu; Kim, Hui-Hun; Park, Pil-Hoon; Kwon, Taeg Kyu

    2015-01-01

    In this study, we investigated the effect of 3,4,5-trihydroxy-N-(8-hydroxyquinolin-2-yl)benzamide) (SG-HQ2), a synthetic analogue of gallic acid (3,4,5-trihydroxybenzoic acid), on the mast cell-mediated allergic inflammation and the possible mechanism of action. Mast cells play major roles in immunoglobulin E-mediated allergic responses by the release of histamine, lipid-derived mediators, and pro-inflammatory cytokines. We previously reported the potential effects of gallic acid using allergic inflammation models. For incremental research, we synthesized the SG-HQ2 by the modification of functional groups from gallic acid. SG-HQ2 attenuated histamine release by the reduction of intracellular calcium in human mast cells and primary peritoneal mast cells. The inhibitory efficacy of SG-HQ2 was similar with gallic acid. Enhanced expression of pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin-1β, interleukin-4, and interleukin-6 in activated mast cells was significantly diminished by SG-HQ2 100 times lower concentration of gallic acid. This inhibitory effect was mediated by the reduction of nuclear factor-κB. In animal models, SG-HQ2 inhibited compound 48/80-induced serum histamine release and immunoglobulin E-mediated local allergic reaction, passive cutaneous anaphylaxis. Our results indicate that SG-HQ2, an analogue of gallic acid, might be a possible therapeutic candidate for mast cell-mediated allergic inflammatory diseases through suppression of histamine release and pro-inflammatory cytokines. PMID:25349218

  11. Mono- and binuclear copper(II) complexes of new hydrazone ligands derived from 4,6-diacetylresorcinol: Synthesis, spectral studies and antimicrobial activity.

    PubMed

    Shebl, Magdy; El-ghamry, Mosad A; Khalil, Saied M E; Kishk, Mona A A

    2014-05-21

    Two new hydrazone ligands, H2L(1) and H2L(2), were synthesized by the condensation of 4,6-diacetylresorcinol with 3-hydrazino-5,6-diphenyl-1,2,4-triazine and isatin monohydrazone, respectively. The structures of the ligands were elucidated by elemental analyses, IR, (1)H NMR, electronic and mass spectra. Reactions of the ligands with several copper(II) salts, including AcO(-), NO3(-), SO4(2-), Cl(-) and Br(-) afforded mono- and binuclear metal complexes. Also, the ligands were allowed to react with Cu(II) ion in the presence of a secondary ligand (L') [N,O-donor; 8-hydroxyquinoline, N,N-donor; 1,10-phenanthroline or O,O-donor; benzoylacetone]. Characterization and structure elucidation of the prepared complexes were achieved by elemental and thermal analyses, IR, electronic, mass and ESR spectra as well as conductivity and magnetic susceptibility measurements. The ESR spin Hamiltonian parameters of some complexes were calculated. The spectroscopic data showed that the H2L(1) ligand acts as a neutral or monobasic tridentate ligand while the H2L(2) ligand acts as a bis(monobasic tridentate) ligand. The coordination sites with the copper(II) ion are phenolic oxygen, azomethine nitrogen and triazinic nitrogen (H2L(1) ligand) or isatinic oxygen (H2L(2) ligand). The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. The ligands and some metal complexes showed antimicrobial activity. PMID:24607473

  12. Optoelectronic Properties of Color-Tunable Mixed Ligand-Based Light-Emitting Zinc Complexes

    NASA Astrophysics Data System (ADS)

    Singh, Devender; Bhagwan, Shri; Saini, Raman Kumar; Tanwar, Vijeta; Nishal, Vandna

    2016-10-01

    A series of mixed ligand-based zinc complexes (Zn1-Zn5); [(8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn1), [(5-chloro-8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn2), [(5,7-dichloro-8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn3), [(2-methyl-8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn4) and [(5,7-dimethyl-8-hydroxyquinolinato)(2-(2-hydroxyphenyl)benzimidazolato)zinc(II)] (Zn5) were synthesized and characterized. The photophysical properties of zinc complexes were examined by ultraviolet-visible absorption and photoluminescence emission spectroscopy. All prepared metal complexes produced intense luminescence on excitation with a UV light source. In this study, the color-tunable characteristics of metal complexes were investigated by introducing the electron-donating and electron-withdrawing groups on the 8-hydroxyquinoline ligand. The emission spectra of metal complexes showed emission wavelength at 500 nm for [ZnHBI(q)], 509 nm for [ZnHBI(Clq)], 504 nm for [Zn(HBI)(Cl2q)], 496 nm for [ZnHBI (Meq)] and 573 nm for [ZnHBI(Me2Q)] materials. A temperature-dependent PL spectrum was used to study the emission profile of zinc complex and observed that variation in the temperature altered the position and the intensity of emission peak. The synthesized metal complex also exhibited good thermal stability (>300°C). Photophysical characteristics of color-tunable light-emitting zinc complexes suggested that these materials could be efficiently used for emissive display device applications.

  13. Copper Capture in a Thioether-Functionalized Porous Polymer Applied to the Detection of Wilson's Disease.

    PubMed

    Lee, Sumin; Barin, Gokhan; Ackerman, Cheri M; Muchenditsi, Abigael; Xu, Jun; Reimer, Jeffrey A; Lutsenko, Svetlana; Long, Jeffrey R; Chang, Christopher J

    2016-06-22

    Copper is an essential nutrient for life, but at the same time, hyperaccumulation of this redox-active metal in biological fluids and tissues is a hallmark of pathologies such as Wilson's and Menkes diseases, various neurodegenerative diseases, and toxic environmental exposure. Diseases characterized by copper hyperaccumulation are currently challenging to identify due to costly diagnostic tools that involve extensive technical workup. Motivated to create simple yet highly selective and sensitive diagnostic tools, we have initiated a program to develop new materials that can enable monitoring of copper levels in biological fluid samples without complex and expensive instrumentation. Herein, we report the design, synthesis, and properties of PAF-1-SMe, a robust three-dimensional porous aromatic framework (PAF) densely functionalized with thioether groups for selective capture and concentration of copper from biofluids as well as aqueous samples. PAF-1-SMe exhibits a high selectivity for copper over other biologically relevant metals, with a saturation capacity reaching over 600 mg/g. Moreover, the combination of PAF-1-SMe as a material for capture and concentration of copper from biological samples with 8-hydroxyquinoline as a colorimetric indicator affords a method for identifying aberrant elevations of copper in urine samples from mice with Wilson's disease and also tracing exogenously added copper in serum. This divide-and-conquer sensing strategy, where functional and robust porous materials serve as molecular recognition elements that can be used to capture and concentrate analytes in conjunction with molecular indicators for signal readouts, establishes a valuable starting point for the use of porous polymeric materials in noninvasive diagnostic applications.

  14. Seasonal change in the level and the chemical forms of aluminum in soil solution under a Japanese cedar forest.

    PubMed

    Umemura, Tomonari; Usami, Yosuke; Aizawa, Sho-ichi; Tsunoda, Kin-ichi; Satake, Ken-ichi

    2003-12-30

    The level of dissolved aluminum and its chemical forms in soil solutions consecutively collected by a porous cup vacuum sampler were monitored over a period from January 2001 to December 2001 at a Japanese cedar (Cryptomeria japonica) forestry area susceptible to acid deposition to characterize current soil dynamics and to evaluate potential tree damages. Distinction and characterization of Al species with differential toxicities were performed by two complementary speciation techniques; cation-exchange HPLC with fluorometric detection using 8-hydroxyquinoline-5-sulfonic acid (HQS) and size-fractionation/inductively coupled plasma atomic emission spectrometry (ICP-AES). The concentrations of free Al (mainly Al3+ and Al(OH)2+) and inert Al (existing as the complexed and/or colloidal forms) ranged between 0-150 microM and 10-50 microM, respectively. The concentrations of inert Al were mostly below 40 microM during an annual cycle and showed no marked seasonal variation, while free Al concentrations showed a clear tendency to increase in the spring and summer seasons (in the period from April to August) probably due to the enhanced activity of microbial nitrification and the resultant soil acidification. Major cations and anions were also regularly determined and their seasonal changes were correlated with that of the dissolved Al concentration. Correlations between total Al (mainly existing as free Al) and the related species (and environmental conditions) were as follows: Al and Mg (R=0.96, P<0.01), Al and Ca (R=0.97, P<0.01), Al and NO3- (R=0.68, P<0.01), Al and temperature (R=0.68, P<0.01), Al and solution pH (R=-0.61, P<0.01), solution pH and NO3- (R=-0.65, P<0.01).

  15. The role of heavy metal ions on spin transport in organic semiconductors

    NASA Astrophysics Data System (ADS)

    Chen, B. B.; Wang, S.; Jiang, S. W.; Yu, Z. G.; Wan, X. G.; Ding, H. F.; Wu, D.

    2015-01-01

    It is generally believed that spin-orbit coupling (SOC) strength and the associated spin relaxation can be enhanced by introducing heavy metal ions in organic semiconductors. Here, we systematically study the spin transport in two organic semiconductors, tris(2-phenylpyridine)iridium (Ir(ppy)3) and tris-(8-hydroxyquinoline) aluminum (Alq3), which have similar chemical structures except that Ir(ppy)3 contains a heavy metal ion Ir. As expected, the photoluminescence spectroscopy measurements show that the SOC strength in Ir(ppy)3 is several orders of magnitude larger than in Alq3. Surprisingly, the spin diffusion length in Ir(ppy)3, deduced from magnetoresistance measurements in Ir(ppy)3-based organic spin valves, is longer than in Alq3. Considering the lower carrier mobility in Ir(ppy)3, the spin relaxation time in Ir(ppy)3 is much longer than in Alq3, implying that the SOC strength in Ir(ppy)3 is weaker than in Alq3. The seemingly contradictory results of photoluminescence spectroscopy and magneto-transport can be explained by the SOC strength depending on the electronic states of a material. The weak SOC strength in Ir(ppy)3 observed in magneto-transport measurements is due to the strong ligand field induced orbital moment quenching for Ir3+ and the polarons transporting in the ligands. However, the excitons involved in photoluminescence spectroscopy overlap with the Ir ion and transforms Ir3+ to Ir4+, which has non-zero spin and orbital moments and hence results in high SOC strength.

  16. Evaluation of several holding solutions for prolonging vase-life and keeping quality of cut sweet pea flowers (Lathyrus odoratus L.).

    PubMed

    Elhindi, Khalid M

    2012-04-01

    Cut spikes of sweet pea (Lathyrus odoratus L.) were kept in 2% sucrose, 200 ppm 8-hydroxyquinoline sulfate (8-HQS), pulsing treatment with 200 ppm 8-HQS in combination with 2% sucrose for 12 h, pulsing the spikes with 0.2 mM silver thiosulfate (STS) for 1 h and pulsing with 0.2 mM STS for 1 h followed by 2% sucrose solution. Therefore, this study aimed to see their effects on keeping quality and vase-life of the cut flowers. A control (deionized water) and a standard preservative were also included in the experiment. The results showed that all treatments had improved the keeping quality and vase-life of the cut flowers comparing to control ones. Among all these treatments, the 8-HQS combined with 2% sucrose showed the best water uptake, water balance, percentage of maximum increase in fresh weight of the cut flower stems and vase-life which was extended up to 17 days. Moreover, this keeping solution retarded the chlorophyll as well as carbohydrate degradation. However, anthocyanin concentrations were increased by treatments with sucrose alone or STS followed by sucrose during the postharvest life. It has been concluded that 200 ppm 8-HQS combined with 2% sucrose solution has the potential to be used as a commercial cut flower preservative solution to delay flower senescence, enhance post harvest quality and prolong the vase-life of sweet pea cut flowers.

  17. Copper Capture in a Thioether-Functionalized Porous Polymer Applied to the Detection of Wilson's Disease.

    PubMed

    Lee, Sumin; Barin, Gokhan; Ackerman, Cheri M; Muchenditsi, Abigael; Xu, Jun; Reimer, Jeffrey A; Lutsenko, Svetlana; Long, Jeffrey R; Chang, Christopher J

    2016-06-22

    Copper is an essential nutrient for life, but at the same time, hyperaccumulation of this redox-active metal in biological fluids and tissues is a hallmark of pathologies such as Wilson's and Menkes diseases, various neurodegenerative diseases, and toxic environmental exposure. Diseases characterized by copper hyperaccumulation are currently challenging to identify due to costly diagnostic tools that involve extensive technical workup. Motivated to create simple yet highly selective and sensitive diagnostic tools, we have initiated a program to develop new materials that can enable monitoring of copper levels in biological fluid samples without complex and expensive instrumentation. Herein, we report the design, synthesis, and properties of PAF-1-SMe, a robust three-dimensional porous aromatic framework (PAF) densely functionalized with thioether groups for selective capture and concentration of copper from biofluids as well as aqueous samples. PAF-1-SMe exhibits a high selectivity for copper over other biologically relevant metals, with a saturation capacity reaching over 600 mg/g. Moreover, the combination of PAF-1-SMe as a material for capture and concentration of copper from biological samples with 8-hydroxyquinoline as a colorimetric indicator affords a method for identifying aberrant elevations of copper in urine samples from mice with Wilson's disease and also tracing exogenously added copper in serum. This divide-and-conquer sensing strategy, where functional and robust porous materials serve as molecular recognition elements that can be used to capture and concentrate analytes in conjunction with molecular indicators for signal readouts, establishes a valuable starting point for the use of porous polymeric materials in noninvasive diagnostic applications. PMID:27285482

  18. A new dispersive liquid-liquid microextraction using ionic liquid based microemulsion coupled with cloud point extraction for determination of copper in serum and water samples.

    PubMed

    Arain, Salma Aslam; Kazi, Tasneem Gul; Afridi, Hassan Imran; Arain, Mariam Shahzadi; Panhwar, Abdul Haleem; Khan, Naeemullah; Baig, Jameel Ahmed; Shah, Faheem

    2016-04-01

    A simple and rapid dispersive liquid-liquid microextraction procedure based on ionic liquid assisted microemulsion (IL-µE-DLLME) combined with cloud point extraction has been developed for preconcentration copper (Cu(2+)) in drinking water and serum samples of adolescent female hepatitits C (HCV) patients. In this method a ternary system was developed to form microemulsion (µE) by phase inversion method (PIM), using ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) and nonionic surfactant, TX-100 (as a stabilizer in aqueous media). The Ionic liquid microemulsion (IL-µE) was evaluated through visual assessment, optical light microscope and spectrophotometrically. The Cu(2+) in real water and aqueous acid digested serum samples were complexed with 8-hydroxyquinoline (oxine) and extracted into IL-µE medium. The phase separation of stable IL-µE was carried out by the micellar cloud point extraction approach. The influence of of different parameters such as pH, oxine concentration, centrifugation time and rate were investigated. At optimized experimental conditions, the limit of detection and enhancement factor were found to be 0.132 µg/L and 70 respectively, with relative standard deviation <5%. In order to validate the developed method, certified reference materials (SLRS-4 Riverine water) and human serum (Sero-M10181) were analyzed. The resulting data indicated a non-significant difference in obtained and certified values of Cu(2+). The developed procedure was successfully applied for the preconcentration and determination of trace levels of Cu(2+) in environmental and biological samples.

  19. Different materials as a cathode modification layer on the impact of organic solar cells

    NASA Astrophysics Data System (ADS)

    Zhong, Jian; Huang, Qiuyan; Yu, Junsheng; Jiang, Yadong

    2010-10-01

    Organic thin film solar cells based on conjugated polymer or small molecules have showed an interesting approach to energy conversion since Tang reported a single donor-accepter hetero-junction solar cell. The power conversion efficiency of organic solar cells has increased steadily over last decade. Small-molecular weight organic double heterojunction donor-acceptor layer organic solar cells (OSC) with a structure of indium-tin-oxide (ITO)/CuPc(200Å)/C60(400Å)/x/Ag(1000Å), using CuPc(copper Phthalocyanine)as donor layer, and Alq3(8-Hydroxyquinoline aluminum salt), BCP(Bromocresol purple sodium salt) and Bphen(4'7-diphyenyl-1,10-phenanthroline) as cathode modification layer, respectively were fabricated. The performance of OSC was studied as a function of the different materials as an cathode modification layer to optimize the structure. The current-voltage characteristic of the solar cell under AM1.5 solar illumination at an intensity of 100 mw/cm2 showed that the power conversion efficiency (PCE) was dependent of the different materials of the cathode modification layer. the efficiency along with the different materials as an cathode modification layer will diminish under that standard solar illumination(AM1.5)was obtained. Using a double heterostructure of ITO/CuPc(200Å)/C60(400Å)/Alq3(60Å)/Ag(1000Å) with high-vacuum evaporation technology, the efficiency was 0.587%.the efficiency was 0.967% when the material of the cathode modification layer was BCP, with the structure of ITO/CuPc(200Å)/C60(400Å)/BCP(35Å)/Ag(1000Å), and the efficiency was 0.742% when the material of the cathode modification layer was Bphen, with the structure of ITO/CuPc(200Å)/C60(400Å)/ Bphen(50Å)/Ag(1000Å).Using different materials as a cathode modification layer, it can be seen that the material which matches the energy level could even eventually be able to improve the energy conversion efficiency more.

  20. Alkane biosynthesis by decarbonylation of aldehyde catalyzed by a microsomal preparation from Botryococcus braunii.

    PubMed

    Dennis, M W; Kolattukudy, P E

    1991-06-01

    The final step in the synthesis of n-hydrocarbons in an animal and a higher plant involves enzymatic decarbonylation of aldehydes to the corresponding alkanes by loss of the carbonyl carbon. Whether such a novel reaction is involved in hydrocarbon synthesis in the colonial microalga, Botryococcus braunii, which is known to produce unusually high levels (up to 32% of dry weight) of n-C27, C29, and C31 alka-dienes and -trienes, was investigated. Dithioerythritol severely inhibited the incorporation of [1-14C]acetate into these hydrocarbons with accumulation of the label in the aldehyde fraction in the B. braunii cells. Microsomal preparations of the alga synthesized alkane from fatty acid and aldehyde in the absence of O2. Conversion of fatty acid to alkane required CoA, ATP, and NADH, whereas conversion of aldehyde to alkane did not require the addition of cofactors. That the alkane synthesis involves a decarbonylation was shown by the production of CO and heptadecane from octadecanal. CO was identified by adsorption to RhCl[(C6H6)3P]3. The decarbonylase had a pH optimum at 7.0, an apparent Km of 65 microM, a Vmax of 1.36 nmol/min/mg and was inhibited by the metal chelators EDTA, O-phenanthroline and 8-hydroxyquinoline. It was stimulated nearly threefold by 2 mM ascorbate and inhibited by the presence of O2. A partial (28%) retention of the aldehydic hydrogen of [1-3H]octadecanal in the heptadecane was observed; the remaining 3H was lost to H2O. The microsomal preparation also catalyzed the oxidation of 14CO to 14CO2, with a pH optimum of 7.0. This accounts for the nonstoichiometry of CO to heptadecane observed. In vivo studies with 14CO showed that the label was incorporated into metabolic products. This metabolic conversion of CO, not found in the previously examined hydrocarbon synthesizing systems, may be necessary for organisms that produce large amounts of hydrocarbons such as the present alga. The mechanism of the decarbonylation and the nature of the

  1. Microsomal preparation from an animal tissue catalyzes release of carbon monoxide from a fatty aldehyde to generate an alkane.

    PubMed

    Cheesbrough, T M; Kolattukudy, P E

    1988-02-25

    Alkanes are widely distributed in nature and impaired alkane synthesis was implicated in certain neurological disorders. However, the mechanism of synthesis of alkanes in animals is unknown. Our search to find a convenient animal tissue to study alkane biosynthesis resulted in the finding that the uropygial gland (a modified sebaceous gland) of the eared grebe (Podiceps nigricollis) produces large amounts of alkanes. These alkanes, which constitute 35-41% of the total lipid produced, are mainly C21, C23, C25, and C27 n-alkanes. Cell free homogenates of this tissue synthesized alkanes from both fatty acid and aldehyde in the absence of O2. Differential centrifugation of the homogenates indicated that this activity was located in the microsomal fraction. With isolated microsomes conversion of fatty acid to alkane required CoA, ATP, and NADH whereas conversion of an aldehyde to alkane did not require the addition of cofactors. That the final step in alkane synthesis is a decarbonylation was shown by the stoichiometric production of heptadecane and CO from octadecanal. CO was identified by adsorption to RhCl [(C6H6)3P]3 and oxidation of the trapped CO to CO2 by watergas shift reaction. The enzyme preparation also catalyzed incorporation of 14C from 14CO into octadecanal showing the reversible nature of the decarbonylase. This decarbonylase had a sharp pH optimum at 7.0, a Kapp of 180 microM and a V1/2 of 90 rho mol/min/mg protein for octadecanal. The enzyme was inhibited by the metal chelators EDTA, O-phenanthroline, and 8-hydroxyquinoline, but not by KCN. It was stimulated nearly 3-fold by 5 microM 2-mercaptoethanol and inhibited by the presence of O2. During the conversion of [1-3H]octadecanal to heptadecane, 3H was lost to water and 3H from 3H2O was incorporated into the alkane generated from unlabeled octadecanal. The mechanism of the decarbonylation and the nature of the enzyme remain to be elucidated.

  2. Degradation in organic light emitting devices

    NASA Astrophysics Data System (ADS)

    Dinh, Vincent Vinh

    This thesis is about the fundamental causes of degradation in tris(8-Hydroxyquinoline) Aluminum (Alq3)-based organic light emitting diodes (OLEDs). Degradation typically occurs when a current is forced through an insulating material. Since the insulator does not support conduction waves (in its ground state), chemical restructuring must occur to accommodate the current. OLEDs have many technical advantages over the well known semiconductor-based light emitting diodes (LEDs). OLEDs have quantum efficiencies ˜1% (˜10 times higher than the LEDs), and operational power thresholds ˜.05mW (˜100 lower than the LEDs). OLEDs are preferred in power limited and portable devices; devices such as laptops and displays consume ˜1/4 of the supplied power---any power saving is significant. Other advantages, like better compliance to curved surfaces and ease of fabrication, give the OLEDs an even greater edge over the LEDs. OLEDs must have at least comparable or better lifetimes to remain attractive. Typical OLEDs last several 100hrs compared to the several 1000hrs for the LEDs. For reliable OLED application, it is necessary to understand the above breakdown mechanism. In this thesis, we attempt to understand the breakdown by looking at how OLEDs are made, how they work, and when they don't. In the opening sections, we give an overview of OLEDs and LEDs, especially how sustained luminescence is achieved through current circulation. Then in Chapter 2, we look at the basic components in the OLEDs. In Chapter 3 we look at how a hole material (like poly-vinyl carbazole or PVK) establishes an excitonic environment for the sustained luminescence in Alq3. We then approximate how potential is distributed when a simple luminescence system is in operation. In Chapter 4, we look at ways of measuring this distribution via the OLED impedance. Finally in Chapter 5, we look at the OLED stability under light emission conditions via PVK and Alq3 photoemission and photoabsorption spectra

  3. Calorimetric studies of the interactions of metalloenzyme active site mimetics with zinc-binding inhibitors.

    PubMed

    Robinson, Sophia G; Burns, Philip T; Miceli, Amanda M; Grice, Kyle A; Karver, Caitlin E; Jin, Lihua

    2016-07-19

    The binding of drugs to metalloenzymes is an intricate process that involves several interactions, including binding of the drug to the enzyme active site metal, as well as multiple interactions between the drug and the enzyme residues. In order to determine the free energy contribution of Zn(2+) binding by known metalloenzyme inhibitors without the other interactions, valid active site zinc structural mimetics must be formed and binding studies need to be performed in biologically relevant conditions. The potential of each of five ligands to form a structural mimetic with Zn(2+) was investigated in buffer using Isothermal Titration Calorimetry (ITC). All five ligands formed strong 1 : 1 (ligand : Zn(2+)) binary complexes. The complexes were used in further ITC experiments to study their interaction with 8-hydroxyquinoline (8-HQ) and/or acetohydroxamic acid (AHA), two bidentate anionic zinc-chelating enzyme inhibitors. It was found that tetradentate ligands were not suitable for creating zinc structural mimetics for inhibitor binding in solution due to insufficient coordination sites remaining on Zn(2+). A stable binary complex, [Zn(BPA)](2+), which was formed by a tridentate ligand, bis(2-pyridylmethyl)amine (BPA), was found to bind one AHA in buffer or a methanol : buffer mixture (60 : 40 by volume) at pH 7.25 or one 8-HQ in the methanol : buffer mixture at pH 6.80, making it an effective structural mimetic for the active site of zinc metalloenzymes. These results are consistent with the observation that metalloenzyme active site zinc ions have three residues coordinated to them, leaving one or two sites open for inhibitors to bind. Our findings indicate that Zn(BPA)X2 can be used as an active site structural mimetic for zinc metalloenzymes for estimating the free energy contribution of zinc binding to the overall inhibitor active site interactions. Such use will help aid in the rational design of inhibitors to a variety of zinc metalloenzymes

  4. Optical, electrical, and magnetic field studies of organic materials for light emitting diodes and photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Basel, Tek Prasad

    We studied optical, electrical, and magnetic field responses of films and devices based on organic semiconductors that are used for organic light emitting diodes (OLEDs) and photovoltaic (OPV) solar cell applications. Our studies show that the hyperfine interaction (HFI)-mediated spin mixing is the key process underlying various magnetic field effects (MFE) and spin transport in aluminum tris(8-hydroxyquinoline)[Alq3]-based OLEDs and organic spin-valve (OSV). Conductivity-detected magnetic resonance in OLEDs and magneto-resistance (MR) in OSVs show substantial isotope dependence. In contrast, isotope-insensitive behavior in the magneto-conductance (MC) of same devices is explained by the collision of spin ½ carriers with triplet polaron pairs. We used steady state optical spectroscopy for studying the energy transfer dynamics in films and OLEDs based on host-guest blends of the fluorescent polymer and phosphorescent molecule. We have also studied the magnetic-field controlled color manipulation in these devices, which provide a strong proof for the `polaron-pair' mechanism underlying the MFE in organic devices. The critical issue that hampers organic spintronics device applications is significant magneto-electroluminescence (MEL) at room temperature (RT). Whereas inorganic spin valves (ISVs) show RT magneto-resistance, MR>80%, however, the devices do not exhibit electroluminescence (EL). In contrast, OLEDs show substantive EL emission, and are particularly attractive because of their flexibility, low cost, and potential for multicolor display. We report a conceptual novel hybrid organic/inorganic spintronics device (h-OLED), where we employ both ISV with large MR at RT, and OLED that has efficient EL emission. We investigated the charge transfer process in an OPV solar cell through optical, electrical, and magnetic field measurements of thin films and devices based on a low bandgap polymer, PTB7 (fluorinated poly-thienothiophene-benzodithiophene). We found that

  5. Inductively coupled plasma-optical emission spectrometry/mass spectrometry for the determination of Cu, Ni, Pb and Zn in seawater after ionic imprinted polymer based solid phase extraction.

    PubMed

    Otero-Romaní, Jacobo; Moreda-Piñeiro, Antonio; Bermejo-Barrera, Pilar; Martin-Esteban, Antonio

    2009-08-15

    The capabilities of a synthesized ionic imprinted polymer (IIP), originally prepared for Ni recognition/pre-concentration from seawater, have been evaluated for other trace elements pre-concentration. The polymer has been synthesized by the precipitation polymerization technique using a ternary pre-polymerization complex formed by the template (Ni), the monomer (2-(diethylamino) ethyl methacrylate, DEM) and a non-vinylated chelating agent (8-hydroxyquinoline, 8-HQ). Since the complexing agent (8-HQ) is trapped into the polymeric matrix, but is not linked to the polymer chains, specific interactions between the functional groups (present in the monomer and the complexing agent) and other trace elements rather than Ni may occur. Results have shown that the IIP offers imprinting properties for the template (Ni(II)) and also for Cu(II), Pb(II), Zn(II), As(V) and Cd(II), with analytical recoveries close to 100% for all elements except for As(V) and Cd(II) (around 70%), whereas the non-imprinted polymer (NIP) did not show affinity for any trace element. In addition, the polymer does not interact with alkaline or alkaline-earth metals, so Na, K, Mg and Ca from the seawater salt matrix could be effectively removed. Variables affecting the IIP-solid phase extraction (SPE) process (pH, load flow rate and concentration and volume of the eluting solution) were completely studied. Inductively coupled plasma-optical emission spectrometry (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) have been used as multi-element detectors. Acidified seawater samples must only be treated to fix an alkaline pH (8.5+/-0.5) and passed through IIP-SPE cartridges. After seawater sample loading (250 mL), analytes were eluted with 2.5 mL of 2.0M nitric acid, offering a pre-concentration factor of 100. Therefore, the limits of detection (LODs) of the method were 0.14, 0.15, 0.18 and 0.03 microg L(-1), for Ni, Cu, Pb and Zn, respectively, when using ICP-OES detection and 0.0022, 0

  6. Further phenotypic characterization of pso mutants of Saccharomyces cerevisiae with respect to DNA repair and response to oxidative stress.

    PubMed

    Pungartnik, Cristina; Picada, Jaqueline; Brendel, Martin; Henriques, João A P

    2002-03-31

    The sensitivity responses of seven pso mutants of Saccharomyces cerevisiae towards the mutagens N-nitrosodiethylamine (NDEA), 1,2:7,8-diepoxyoctane (DEO), and 8-hydroxyquinoline (8HQ) further substantiated their allocation into two distinct groups: genes PSO1 (allelic to REV3), PSO2 (SNM1), PSO4 (PRP19), and PSO5 (RAD16) constitute one group in that they are involved in repair of damaged DNA or in RNA processing whereas genes PSO6 (ERG3) and PSO7 (COX11) are related to metabolic steps protecting from oxidative stress and thus form a second group, not responsible for DNA repair. PSO3 has not yet been molecularly characterized but its pleiotropic phenotype would allow its integration into either group. The first three PSO genes of the DNA repair group and PSO3, apart from being sensitive to photo-activated psoralens, have another common phenotype: they are also involved in error-prone DNA repair. While all mutants of the DNA repair group and pso3 were sensitive to DEO and NDEA the pso6 mutant revealed WT or near WT resistance to these mutagens. As expected, the repair-proficient pso7-1 and cox11-Delta mutant alleles conferred high sensitivity to NDEA, a chemical known to be metabolized via redox cycling that yields hydroxylamine radicals and reactive oxygen species. All pso mutants exhibited some sensitivity to 8HQ and again pso7-1 and cox11-Delta conferred the highest sensitivity to this drug. Double mutant snm1-Delta cox11-Delta exhibited additivity of 8HQ and NDEA sensitivities of the single mutants, indicating that two different repair/recovery systems are involved in survival. DEO sensitivity of the double mutant was equal or less than that of the single snm1-Delta mutant. In order to determine if there was oxidative damage to nucleotide bases by these drugs we employed an established bacterial test with and without metabolic activation. After S9-mix biotransformation, NDEA and to a lesser extent 8HQ, lead to significantly higher mutagenesis in an Escherichia

  7. AS-2, a novel inhibitor of p53-dependent apoptosis, prevents apoptotic mitochondrial dysfunction in a transcription-independent manner and protects mice from a lethal dose of ionizing radiation

    SciTech Connect

    Morita, Akinori; Ariyasu, Shinya; Wang, Bing; Asanuma, Tetsuo; Onoda, Takayoshi; Sawa, Akiko; Tanaka, Kaoru; Takahashi, Ippei; Togami, Shotaro; Nenoi, Mitsuru; Inaba, Toshiya; Aoki, Shin

    2014-08-08

    Highlights: • A bidentate HQ derivative, AS-2, suppresses p53-dependent apoptosis by DNA damage. • AS-2 does not significantly affect nuclear p53 response. • UV-excited blue emission of AS-2 clearly showed its extranuclear localization. • AS-2 prevents mitochondrial dysfunction despite the increase of mitochondrial p53. • AS-2 protects mice from a radiation dose that causes lethal hematopoietic syndrome. - Abstract: In a previous study, we reported that some tetradentate zinc(II) chelators inhibit p53 through the denaturation of its zinc-requiring structure but a chelator, Bispicen, a potent inhibitor of in vitro apoptosis, failed to show any efficient radioprotective effect against irradiated mice because the toxicity of the chelator to mice. The unsuitability of using tetradentate chelators as radioprotectors prompted us to undertake a more extensive search for p53-inhibiting agents that are weaker zinc(II) chelators and therefore less toxic. Here, we show that an 8-hydroxyquinoline (8HQ) derivative, AS-2, suppresses p53-dependent apoptosis through a transcription-independent mechanism. A mechanistic study using cells with different p53 characteristics revealed that the suppressive effect of AS-2 on apoptosis is specifically mediated through p53. In addition, AS-2 was less effective in preventing p53-mediated transcription-dependent events than pifithrin-μ (PFTμ), an inhibitor of transcription-independent apoptosis by p53. Fluorescence visualization of the extranuclear distribution of AS-2 also supports that it is ineffective on the transcription-dependent pathway. Further investigations revealed that AS-2 suppressed mitochondrial apoptotic events, such as the mitochondrial release of intermembrane proteins and the loss of mitochondrial membrane potential, although AS-2 resulted in an increase in the mitochondrial translocation of p53 as opposed to the decrease of cytosolic p53, and did not affect the apoptotic interaction of p53 with Bcl-2. AS-2 also

  8. Experimental and theoretical approach of photophysical properties of lanthanum(III) and erbium(III) complexes of tris(methoxymethyl)-5-oxine podant.

    PubMed

    Akbar, Rifat; Baral, Minati; Kanungo, B K

    2014-08-14

    With the aim of evaluating the coordination behavior of a novel polydentate tripodal ligand, 5-[[3-[(8-hydroxy-5-quinolyl)methoxy]-2-[(8-hydroxy-5-quinolyl)methoxymethyl]-2-methyl propoxy]methyl]quinolin-8-ol (TMOM5OX), towards La(III) and Er(III) metal ions, the detailed investigations of photophysical properties by theoritical and experimental (potentiometric, UV-visible and fluorescence spectrophotometry) methods were carried out. TMOM5OX has been found to form protonated complex [Ln(H4L)](4+) (Ln=La or Er) below pH 3.8, which consecutively deprotonates through one-proton processes with rise of pH. The formation constants (logβ) of neutral complexes have been determined to be 36.42 (LaL) and 35.76, 37.62 (for ErL and ErL2, respectively) and the pLn (pLn=-log[Ln(3+)]) values of 24.6 and 27.1 for La(III) and Er(III) ions, respectively, calculated at pH 7.4, indicating TMOM5OX is a good lanthanide synthetic chelator. The absorption spectroscopy of these complexes show marked spectral variations due to characteristic lanthanide transitions, which support the use of TMOM5OX as a sensitive optical pH based sensor to detect Ln(III) metal ions in biological systems. In addition, these complexes have also been shown to exhibit strong green fluorescence allowing simultaneous sensing within the visible region under physiological pH in competitive medium for both La(III) and Er(III) ions. The intense fluorescence from these compounds were revealed to intermittently get quenched under acidic and basic conditions due to the photoinduced intramolecular electron transfer from excited 8-hydroxyquinoline (8-HQ) moiety to metal ion, just an opposite process. This renders these compounds the OFF-ON-OFF type of pH-dependent fluorescent sensors. The complexes coordination geometries were optimized using the sparkle/PM6 model and the theoretical spectrophotometric studies were carried out in order to validate the experimental findings, based on ZINDO/S methodology at configuration

  9. Experimental and theoretical approach of photophysical properties of lanthanum(III) and erbium(III) complexes of tris(methoxymethyl)-5-oxine podant

    NASA Astrophysics Data System (ADS)

    Akbar, Rifat; Baral, Minati; Kanungo, B. K.

    2014-08-01

    With the aim of evaluating the coordination behavior of a novel polydentate tripodal ligand, 5-[[3-[(8-hydroxy-5-quinolyl)methoxy]-2-[(8-hydroxy-5-quinolyl)methoxymethyl]-2-methyl propoxy]methyl]quinolin-8-ol (TMOM5OX), towards La(III) and Er(III) metal ions, the detailed investigations of photophysical properties by theoritical and experimental (potentiometric, UV-visible and fluorescence spectrophotometry) methods were carried out. TMOM5OX has been found to form protonated complex [Ln(H4L)]4+ (Ln = La or Er) below pH 3.8, which consecutively deprotonates through one-proton processes with rise of pH. The formation constants (log β) of neutral complexes have been determined to be 36.42 (LaL) and 35.76, 37.62 (for ErL and ErL2, respectively) and the pLn (pLn = -log[Ln3+]) values of 24.6 and 27.1 for La(III) and Er(III) ions, respectively, calculated at pH 7.4, indicating TMOM5OX is a good lanthanide synthetic chelator. The absorption spectroscopy of these complexes show marked spectral variations due to characteristic lanthanide transitions, which support the use of TMOM5OX as a sensitive optical pH based sensor to detect Ln(III) metal ions in biological systems. In addition, these complexes have also been shown to exhibit strong green fluorescence allowing simultaneous sensing within the visible region under physiological pH in competitive medium for both La(III) and Er(III) ions. The intense fluorescence from these compounds were revealed to intermittently get quenched under acidic and basic conditions due to the photoinduced intramolecular electron transfer from excited 8-hydroxyquinoline (8-HQ) moiety to metal ion, just an opposite process. This renders these compounds the OFF-ON-OFF type of pH-dependent fluorescent sensors. The complexes coordination geometries were optimized using the sparkle/PM6 model and the theoretical spectrophotometric studies were carried out in order to validate the experimental findings, based on ZINDO/S methodology at configuration

  10. Tuning the hydrolytic aqueous chemistry of osmium arene complexes with N,O-chelating ligands to achieve cancer cell cytotoxicity.

    PubMed

    Peacock, Anna F A; Parsons, Simon; Sadler, Peter J

    2007-03-21

    Potential biological and medical applications of organometallic complexes are hampered by a lack of knowledge of their aqueous solution chemistry. We show that the hydrolytic and aqueous solution chemistry of half-sandwich OsII arene complexes of the type [(eta6-arene)Os(XY)Cl] can be tuned with XY chelating ligands to achieve cancer cell cytoxicity comparable to carboplatin. Complexes containing arene = p-cymene, XY = N,O-chelating ligands glycinate (1), L-alaninate (2), alpha-aminobutyrate (3), beta-alaninate (4), picolinate (5), or 8-hydroxyquinolinate (7) were synthesized. Although, 1-4 and 7 hydrolyzed rapidly (

  11. Small molecules with ambipolar transporting properties for efficient OLEDs

    NASA Astrophysics Data System (ADS)

    Duan, Lian; Wei, Peng; Qiu, Yong

    2007-11-01

    For stable and efficienct organic light-emitting diodes, it is essential to find molecules with high photoluminescent efficiency, little self-quenching and balanced charge transporting properties. Recently, we've designed and synthesized some highly emissive naphtho[2,3-c][1,2,5]thiadiazole (NTD) derivatives and naphtho[2,3-c][1,2,5]selenadiazole (NSeD) derivatives with unusual ambipolar transporting properties. The ambipolar transporting properties of the NTDs were explained by Marcus theory with carrier reorganization energies and charge-transfer integrals. We obtained high quality single crystals of 4,9-di(biphenyl-4-yl)-naphtho[2,3-c][1,2,5]thiadiazole (NTD02) and 4,9-bis(4-(2,2-diphenylvinyl)phenyl)-naphtho[2,3-c][1,2,5]thiadiazole (NTD05). They have disordered NTD rings' orientation with the opposite directions in the center of the molecule because of NTD's planar configuration and the single-bond connection with the phenyl substituents. The packing structure of NTD02 shows the planar arrangement of NTD rings, forming a "charge transporting channel". Quantum calculation also confirms that the π-π stacking interaction in NTD derivatives benefits the charge transporting via intermolecular hopping on NTD rings. The hole and electron mobilities of NTD05 are 7.16×10 -4 cm2/VÂ.s and 6.19×10 -4 cm2/V•s at an electronic field E = 2.0×10 5 V/cm, respectively. The hole mobility of NTD05 is close to that of N,N'-diphenyl-N,N'-bis(1-naphthyl)(1,1'-biphenyl)-4,4'-diamine (NPB) and the electron mobility of NTD05 is two orders-of-magnitude higher than that of tris(8-hydroxyquinoline) aluminum (Alq 3). For the NTD derivatives, NTD05 also shows the best performance in non-doped OLEDs. CIE coordinates of (0.65, 0.35) and a peak efficiency of 2.4% are achieved for a double layer OLED with NPB as the hole transporting layer and NTD05 as the emitting layer. Moreover, we get ultimate red emission with CIE coordinates of (0.71, 0.29) for some of the NSeD based non

  12. Ultrahigh density array of vertically aligned small-molecular organic nanowires on arbitrary substrates.

    PubMed

    Starko-Bowes, Ryan; Pramanik, Sandipan

    2013-01-01

    In recent years π-conjugated organic semiconductors have emerged as the active material in a number of diverse applications including large-area, low-cost displays, photovoltaics, printable and flexible electronics and organic spin valves. Organics allow (a) low-cost, low-temperature processing and (b) molecular-level design of electronic, optical and spin transport characteristics. Such features are not readily available for mainstream inorganic semiconductors, which have enabled organics to carve a niche in the silicon-dominated electronics market. The first generation of organic-based devices has focused on thin film geometries, grown by physical vapor deposition or solution processing. However, it has been realized that organic nanostructures can be used to enhance performance of above-mentioned applications and significant effort has been invested in exploring methods for organic nanostructure fabrication. A particularly interesting class of organic nanostructures is the one in which vertically oriented organic nanowires, nanorods or nanotubes are organized in a well-regimented, high-density array. Such structures are highly versatile and are ideal morphological architectures for various applications such as chemical sensors, split-dipole nanoantennas, photovoltaic devices with radially heterostructured "core-shell" nanowires, and memory devices with a cross-point geometry. Such architecture is generally realized by a template-directed approach. In the past this method has been used to grow metal and inorganic semiconductor nanowire arrays. More recently π-conjugated polymer nanowires have been grown within nanoporous templates. However, these approaches have had limited success in growing nanowires of technologically important π-conjugated small molecular weight organics, such as tris-8-hydroxyquinoline aluminum (Alq3), rubrene and methanofullerenes, which are commonly used in diverse areas including organic displays, photovoltaics, thin film transistors

  13. Ultrahigh Density Array of Vertically Aligned Small-molecular Organic Nanowires on Arbitrary Substrates

    PubMed Central

    Starko-Bowes, Ryan; Pramanik, Sandipan

    2013-01-01

    In recent years π-conjugated organic semiconductors have emerged as the active material in a number of diverse applications including large-area, low-cost displays, photovoltaics, printable and flexible electronics and organic spin valves. Organics allow (a) low-cost, low-temperature processing and (b) molecular-level design of electronic, optical and spin transport characteristics. Such features are not readily available for mainstream inorganic semiconductors, which have enabled organics to carve a niche in the silicon-dominated electronics market. The first generation of organic-based devices has focused on thin film geometries, grown by physical vapor deposition or solution processing. However, it has been realized that organic nanostructures can be used to enhance performance of above-mentioned applications and significant effort has been invested in exploring methods for organic nanostructure fabrication. A particularly interesting class of organic nanostructures is the one in which vertically oriented organic nanowires, nanorods or nanotubes are organized in a well-regimented, high-density array. Such structures are highly versatile and are ideal morphological architectures for various applications such as chemical sensors, split-dipole nanoantennas, photovoltaic devices with radially heterostructured "core-shell" nanowires, and memory devices with a cross-point geometry. Such architecture is generally realized by a template-directed approach. In the past this method has been used to grow metal and inorganic semiconductor nanowire arrays. More recently π-conjugated polymer nanowires have been grown within nanoporous templates. However, these approaches have had limited success in growing nanowires of technologically important π-conjugated small molecular weight organics, such as tris-8-hydroxyquinoline aluminum (Alq3), rubrene and methanofullerenes, which are commonly used in diverse areas including organic displays, photovoltaics, thin film transistors

  14. Quinoline-n-butylcyanoacrylate-based nanoparticles for brain targeting for the diagnosis of Alzheimer's disease.

    PubMed

    Kulkarni, Padmakar V; Roney, Celeste A; Antich, Peter P; Bonte, Frederick J; Raghu, Anjanapura V; Aminabhavi, Tejraj M

    2010-01-01

    A survey of research activity on nanoparticles (NPs) based on polymeric devices that could cross the blood-brain barrier (BBB) is given along with the presentation of our own data on the development of NPs of n-butyl-2-cyanoacrylate (BCA) for brain delivery to aid the early diagnosis of Alzheimer's disease (AD), a neurodegenerative disorder of the elderly people, the most prevalent form of dementia. Typical data are presented on in vivo detection of amyloid peptides (A beta) (amyloid plaques) that are used as targets for developing the biological markers for the diagnosis of AD. In order to develop efficient in vivo probes, polymeric n-butyl-2-cyanoacrylate (PBCA) NPs have been prepared and encapsulated with the radio-labeled amyloid affinity drug (125)I-clioquinol (CQ, 5-chloro-7-iodo-8-hydroxyquinoline) to improve the transport to brain and amyloid plaque retention of (125)I-CQ using the NPs of PBCA. The (125)I-CQ discriminately binds to the AD post-mortem brain tissue homogenates versus control. (125)I-CQ-PBCA NPs labeled the A beta plaques from the AD human post-mortem frontal cortical sections on paraffin-fixed slides. Storage phosphor imaging verified preferential uptake by AD brain sections compared to cortical control sections. The (125)I-CQ-PBCA NPs crossed the BBB in wild type mouse, giving an increased brain uptake measured in terms of % ID/g i.e., injected dose compared to (125)I-CQ. Brain retention of (125)I-CQ-PBCA NPs was significantly increased in the AD transgenic mice (APP/PS1) and in mice injected with aggregated A beta 42 peptide versus age-matched wild type controls. The results of this study are verified by in vivo storage phosphor imaging and validated by histopathological staining of plaques and select metal ions, viz. Fe(2+) and Cu(2+). The (125)I-CQ-PBCA NPs had more efficient brain entry and rapid clearance in normal mice and enhanced the retention in AD mouse brain demonstrating the ideal in vivo imaging characteristics. The (125)I

  15. Differential modulation of Alzheimer's disease amyloid beta-peptide accumulation by diverse classes of metal ligands.

    PubMed

    Caragounis, Aphrodite; Du, Tai; Filiz, Gulay; Laughton, Katrina M; Volitakis, Irene; Sharples, Robyn A; Cherny, Robert A; Masters, Colin L; Drew, Simon C; Hill, Andrew F; Li, Qiao-Xin; Crouch, Peter J; Barnham, Kevin J; White, Anthony R

    2007-11-01

    Biometals have an important role in AD (Alzheimer's disease) and metal ligands have been investigated as potential therapeutic agents for treatment of AD. In recent studies the 8HQ (8-hydroxyquinoline) derivative CQ (clioquinol) has shown promising results in animal models and small clinical trials; however, the actual mode of action in vivo is still being investigated. We previously reported that CQ-metal complexes up-regulated MMP (matrix metalloprotease) activity in vitro by activating PI3K (phosphoinositide 3-kinase) and JNK (c-jun N-terminal kinase), and that the increased MMP activity resulted in enhanced degradation of secreted Abeta (amyloid beta) peptide. In the present study, we have further investigated the biochemical mechanisms by which metal ligands affect Abeta metabolism. To achieve this, we measured the effects of diverse metal ligands on cellular metal uptake and secreted Abeta levels in cell culture. We report that different classes of metal ligands including 8HQ and phenanthroline derivatives and the sulfur compound PDTC (pyrrolidine dithiocarbamate) elevated cellular metal levels (copper and zinc), and resulted in substantial loss of secreted Abeta. Generally, the ability to inhibit Abeta levels correlated with a higher lipid solubility of the ligands and their capacity to increase metal uptake. However, we also identified several ligands that potently inhibited Abeta levels while only inducing minimal change to cellular metal levels. Metal ligands that inhibited Abeta levels [e.g. CQ, 8HQ, NC (neocuproine), 1,10-phenanthroline and PDTC] induced metal-dependent activation of PI3K and JNK, resulting in JNK-mediated up-regulation of metalloprotease activity and subsequent loss of secreted Abeta. The findings in the present study show that diverse metal ligands with high lipid solubility can elevate cellular metal levels resulting in metalloprotease-dependent inhibition of Abeta. Given that a structurally diverse array of ligands was assessed, the

  16. Tyrosinase and catechol oxidase activity of copper(I) complexes supported by imidazole-based ligands: structure-reactivity correlations.

    PubMed

    Wendt, Franziska; Näther, Christian; Tuczek, Felix

    2016-09-01

    Four new imidazole-based ligands, 4-((1H-imidazol-4-yl)methyl)-2-phenyl-4,5-dihydrooxyzole (L OL 1), 4-((1H-imidazol-4-yl)methyl)-2-(tert-butyl)-4,5-dihydrooxyzole (L OL 2), 4-((1H-imidazol-4-yl)methyl)-2-methyl-4,5-dihydrooxyzole (L OL 3), and N-(2,2-dimethylpropylidene)-2-(1-trityl-1H-imidazol-4-yl-)ethyl amine (L imz 1), have been synthesized. The corresponding copper(I) complexes [Cu(I)(L OL 1)(CH3CN)]PF6 (CuL OL 1), [Cu(I)(L OL 2)(CH3CN)]PF6 (CuL OL 2), [Cu(I)(L OL 3)(CH3CN)]PF6 (CuL OL 3), [Cu(I)(L imz 1)(CH3CN)2]PF6 (CuL imz 1) as well as the Cu(I) complex derived from the known ligand bis(1-methylimidazol-2-yl)methane (BIMZ), [Cu(I)(BIMZ)(CH3CN)]PF6 (CuBIMZ), are screened as catalysts for the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC-H2) to 3,5-di-tert-butylquinone (3,5-DTBQ). The primary reaction product of these oxidations is 3,5-di-tert-butylsemiquinone (3,5-DTBSQ) which slowly converts to 3,5-DTBQ. Saturation kinetic studies reveal a trend of catalytic activity in the order CuL OL 3 ≈ CuL OL 1 > CuBIMZ > CuL OL 2 > CuL imz 1. Additionally, the catalytic activity of the copper(I) complexes towards the oxygenation of monophenols is investigated. As substrates 2,4-di-tert-butylphenol (2,4-DTBP-H), 3-tert-butylphenol (3-TBP-H), 4-methoxyphenol (4-MeOP-H), N-acetyl-L-tyrosine ethyl ester monohydrate (NATEE) and 8-hydroxyquinoline are employed. The oxygenation products are identified and characterized with the help of UV/Vis and NMR spectroscopy, mass spectrometry, and fluorescence measurements. Whereas the copper complexes with ligands containing combinations of imidazole and imine functions or two imidazole units (CuL imz 1 and CuBIMZ) are found to exhibit catalytic tyrosinase activity, the systems with ligands containing oxazoline just mediate a stoichiometric conversion. Correlations between the structures of the complexes and their reactivities are discussed. PMID:27333775

  17. Photometric flow injection determination of phosphate on a PDMS microchip using an optical detection system assembled with an organic light emitting diode and an organic photodiode.

    PubMed

    Liu, Rong; Ishimatsu, Ryoichi; Yahiro, Masayuki; Adachi, Chihaya; Nakano, Koji; Imato, Toshihiko

    2015-01-01

    A compact photometric detector was constructed from an organic light emitting diode (OLED) based on a europium complex, europium(diben-zoylmethanato)3(bathophenanthroline) (Eu(DBM)3bath), as the light source and an organic photodiode (OPD) fabricated from a hetero-junction of two layers of copper phthalocyanine (CuPc)/fullerene (C60) as the photo-detector on a microchip prepared from poly(dimethylsiloxan) (PDMS) and was applied to the determination of phosphate. The OLED and the OPD were fabricated by a vapor deposition method on an indium tin oxide (ITO) coated glass substrate with the following layered structure; Glass (0.7 mm)/ITO (110 nm)/4,4'-bis[N-(1-naphthyl)-N-phenyl amino]-biphenyl (α-NPD) (30 nm)/4,4'-di(N-carbazolyl)biphenyl (CBP): Eu(3+) (8 wt%, 30 nm)/bathocuproine (BCP) (30 nm)/aluminum tris(8-hydroxyquinoline) (Alq3) (25 nm)/magnesium and silver (MgAg) (100 nm)/Ag (10nm) and Glass (0.7 mm)/ITO (110 nm)/CuPc (35 nm)/C60 (50 nm)/BCP (10 nm)/Ag (50 nm), respectively. The OLED based on the europium complex emitted a sharp light at the wavelength of 612 nm with a full width at half maximum (FWHM) of 8 nm. The performance of the photometric detector assembled was evaluated based on measurements of the absorbance of different concentrations of malachite green (MG) solutions for a batch system with 1cm long path length. The molar absorptive coefficient of the MG solution, calculated from the photocurrent of the OPD, was in good agreement with the value reported in the literature. A microchip with two inlets and one outlet U-shaped channel was prepared by a conventional photolithograph method. The OLED and the OPD were configured so as to face each other through the PDMS microchip in parallel in order to align the light axis of the OLED and the OPD with the flow cell (optical path length of 5mm), which was located at the end of outlet. For the determination of phosphate, an ion-association reaction between MG and a molybdenum-phosphate complex was utilized

  18. Photometric flow injection determination of phosphate on a PDMS microchip using an optical detection system assembled with an organic light emitting diode and an organic photodiode.

    PubMed

    Liu, Rong; Ishimatsu, Ryoichi; Yahiro, Masayuki; Adachi, Chihaya; Nakano, Koji; Imato, Toshihiko

    2015-01-01

    A compact photometric detector was constructed from an organic light emitting diode (OLED) based on a europium complex, europium(diben-zoylmethanato)3(bathophenanthroline) (Eu(DBM)3bath), as the light source and an organic photodiode (OPD) fabricated from a hetero-junction of two layers of copper phthalocyanine (CuPc)/fullerene (C60) as the photo-detector on a microchip prepared from poly(dimethylsiloxan) (PDMS) and was applied to the determination of phosphate. The OLED and the OPD were fabricated by a vapor deposition method on an indium tin oxide (ITO) coated glass substrate with the following layered structure; Glass (0.7 mm)/ITO (110 nm)/4,4'-bis[N-(1-naphthyl)-N-phenyl amino]-biphenyl (α-NPD) (30 nm)/4,4'-di(N-carbazolyl)biphenyl (CBP): Eu(3+) (8 wt%, 30 nm)/bathocuproine (BCP) (30 nm)/aluminum tris(8-hydroxyquinoline) (Alq3) (25 nm)/magnesium and silver (MgAg) (100 nm)/Ag (10nm) and Glass (0.7 mm)/ITO (110 nm)/CuPc (35 nm)/C60 (50 nm)/BCP (10 nm)/Ag (50 nm), respectively. The OLED based on the europium complex emitted a sharp light at the wavelength of 612 nm with a full width at half maximum (FWHM) of 8 nm. The performance of the photometric detector assembled was evaluated based on measurements of the absorbance of different concentrations of malachite green (MG) solutions for a batch system with 1cm long path length. The molar absorptive coefficient of the MG solution, calculated from the photocurrent of the OPD, was in good agreement with the value reported in the literature. A microchip with two inlets and one outlet U-shaped channel was prepared by a conventional photolithograph method. The OLED and the OPD were configured so as to face each other through the PDMS microchip in parallel in order to align the light axis of the OLED and the OPD with the flow cell (optical path length of 5mm), which was located at the end of outlet. For the determination of phosphate, an ion-association reaction between MG and a molybdenum-phosphate complex was utilized

  19. Charge transport and injection in amorphous organic electronic materials

    NASA Astrophysics Data System (ADS)

    Tse, Shing Chi

    This thesis presents how we use various measuring techniques to study the charge transport and injection in organic electronic materials. Understanding charge transport and injection properties in organic solids is of vital importance for improving performance characteristics of organic electronic devices, including organic-light-emitting diodes (OLEDs), photovoltaic cells (OPVs), and field effect transistors (OFETs). The charge transport properties of amorphous organic materials, commonly used in organic electronic devices, are investigated by the means of carrier mobility measurements. Transient electroluminescence (EL) technique was used to evaluate the electron mobility of an electron transporting material--- tris(8-hydroxyquinoline) aluminum (Alq3). The results are in excellent agreement with independent time-of-flight (TOF) measurements. Then, the effect of dopants on electron transport was also examined. TOF technique was also used to examine the effects of tertiary-butyl (t-Bu) substitutions on anthracene derivatives (ADN). All ADN compounds were found to be ambipolar. As the degree of t-Bu substitution increases, the carrier mobilities decrease progressively. The reduction of carrier mobilities with increasing t-butylation can be attributed to a decrease in the charge-transfer integral or the wavefunction overlap. In addition, from TOF measurements, two naphthylamine-based hole transporters, namely, N,N'-diphenyl-N,N'-bis(1-naphthyl)(1,1'-biphenyl)-4,4'diamine (NPB) and 4,4',4"-tris(n-(2-naphthyl)-n-phenyl-amino)-triphenylamine (2TNATA) were found to possess electron-transporting (ET) abilities. An organic light-emitting diode that employed NPB as the ET material was demonstrated. The electron conducting mechanism of NPB and 2TNATA in relation to the hopping model will be discussed. Furthermore, the ET property of NPB applied in OLEDs will also be examined. Besides transient EL and TOF techniques, we also use dark-injection space-charge-limited current