Science.gov

Sample records for 8-hydroxyquinoline

  1. 8-Hydroxyquinolines in medicinal chemistry: A structural perspective.

    PubMed

    Oliveri, Valentina; Vecchio, Graziella

    2016-09-14

    8-Hydroxyquinolines are heterocyclic compounds characterized by a moderate metal-binding affinity. The interest in 8-hydroxyquinolines has grown exponentially in the last two decades as they are privileged structures for the design of new drug candidates that exert a host of biological effects on various targets. The study of biological activities such as neuroprotection, anticancer, antibacterial, antifungal activity has been further promoted by the synthetic versatility of 8-hydroxyquinoline, which allows the generation of a large number of derivatives. These include numerous multifunctional analogues having the metal-binding motif of 8-hydroxyquinoline. In this review, we have summarized 8-hydroxyquinolines, 8-hydroxyquinoline-like compounds, 8-hydroxyquinoline-loaded nanoparticle systems with respect to their biological activities, interaction with metal ions and mechanisms of action. PMID:27191619

  2. DFT studies and vibrational spectra of isoquinoline and 8-hydroxyquinoline

    NASA Astrophysics Data System (ADS)

    Krishnakumar, V.; Ramasamy, R.

    2005-02-01

    The geometry, frequency and intensity of the vibrational bands of isoquinoline (IQ) and 8-hydroxyquinoline (8-HQ) were obtained by the density functional theory (DFT) calculations with the B3LYP functional and 6-31 G* basis set. The vibrational spectral data obtained from the solid phase mid and far FT-IR and FT-Raman spectra of IQ and 8-HQ are assigned based on the results of the normal coordinate calculations. The observed and the calculated spectra are found to be in good agreement.

  3. Polynorbornene derived 8-hydroxyquinoline paper strips for ultrasensitive chemical nerve agent surrogate sensing.

    PubMed

    Sarkar, Santu; Shunmugam, Raja

    2014-08-11

    The detection of nerve agent simulants is achieved by the photoinduced electron transfer (PET) mechanism. A "turn-on" fluorescence response upon phosphorylation at 8-hydroxyquinoline of norbornene-based triazolyl functionalized 8-hydroxyquinoline () followed by intramolecular rearrangement provides very intense green emission. The detection limit of polymer () coated paper strips is 25 ppb with instantaneous response. PMID:24948420

  4. Design and synthesis of 8-hydroxyquinoline-based radioprotective agents.

    PubMed

    Ariyasu, Shinya; Sawa, Akiko; Morita, Akinori; Hanaya, Kengo; Hoshi, Misato; Takahashi, Ippei; Wang, Bing; Aoki, Shin

    2014-08-01

    In radiation therapy, adverse side effects are often induced due to the excessive cell death that occurs in radiosensitive normal cells. The radiation-induced cell death of normal cells is caused, at least in part, by apoptosis, which undergoes via activation of p53 and increase in the p53 protein, a zinc-containing transcriptional factor, in response to cellular damage. Therefore, radioprotective drugs that can protect normal cells from radiation and thus suppress adverse side effects would be highly desirable. We report herein on the radioprotective activity of 8-hydroxyquinoline (8HQ) derivatives that were initially designed so as to interact with the Zn(2+) in p53. Indeed, the 5,7-bis(methylaminosulfonyl)-8HQ and 8-methoxyquinoline derivatives considerably protected MOLT-4 cells against γ-ray radiation (10 Gy), accompanied by a low cytotoxicity. However, mechanistic studies revealed that the interaction of these drugs with p53 is weak and the mechanism for inhibiting apoptosis appears to be different from that of previously reported radioprotectors such as bispicen, which inhibits apoptosis via the denaturation of p53 as well as by blocking both transcription-dependent and -independent apoptotic pathways. PMID:25002230

  5. 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.

  6. Gelation Behavior of 5-Chloro-8-hydroxyquinoline, an Antituberculosis Agent in Aqueous Alcohol Solutions

    PubMed Central

    Kolehmainen, Erkki; Salo, Hannu; Korpela, Jukka

    2012-01-01

    It was shown that 5-chloro-8-hydroxyquinoline, an antituberculosis agent, gels aqueous alcohol solutions efficiently. Thermal stability and gel-to-sol transition temperature of 1% gel in CD3OD/D2O (2:1) was studied by 1H-NMR. Fibrous structures of four xerogels have been characterized by scanning electron microscope. PMID:27029417

  7. Synthesis, antimicrobial, and antiviral activities of some new 5-sulphonamido-8-hydroxyquinoline derivatives.

    PubMed

    Kassem, Emad M; El-Sawy, Eslam R; Abd-Alla, Howaida I; Mandour, Adel H; Abdel-Mogeed, Dina; El-Safty, Mounir M

    2012-06-01

    A series of fused pyranopyrazole and pyranoimidazole, namely 5-(3,6-diamino-4-aryl-5-carbonitrile-pyrano(2,3-c)pyrazol-2-yl)sulphonyl-8-hydroxyquinolines (5a-e), 5-(6-amino-4-aryl-5-carbonitrile-pyrano(2,3-c)pyrazol-3-yl)sulphonamido-8-hydroxyquinolines (6a-e), 5-(2-thioxo-4-aryl-5-carbonitrile-6-amino-pyrano(2,3-d)imidazol-2-yl)sulphonyl-8-hydroxyquinolines (10a-e), and 5-(2-oxo-4-aryl-5-carbonitrile-6-amino-pyrano(2,3-d)imidazol-2-yl) sulphonyl-8-hydroxyquinolines (11a-e), have been prepared via condensation of some arylidine malononitriles with 5-sulphonamido-8-hydroxyquinoline derivatives 3, 4, 8 and 9. All the synthesized compounds were screened for their antimicrobial activities, and most of the tested compounds showed potent inhibition growth activity towards Escherichia coli, Pseudomonas aeruginosa (Gramnegative bacteria). Furthermore, six selected compounds were tested for their antiviral activity against avian paramyxovirus type1 (APMV-1) and laryngotracheitis virus (LTV), and the results showed that a concentration range of 3-4 μg per mL of compounds 2, 3, and 4 showed marked viral inhibitory activity for APMV-1 of 5000 tissue culture infected dose fifty (TCID(50)) and LTV of 500 TCID(50) in Vero cell cultures based on their cytopathic effect. Chicken embryo experiments show that compounds 2, 3, and 4 possess high antiviral activity in vitro with an inhibitory concentration fifty (IC(50)) range of 3-4 μg per egg against avian APMV-1 and LTV and their toxic concentration fifty (CC(50)) of 200-300 μg per egg. PMID:22870804

  8. Magnetic susceptibility of Alq 3 powder, pure and Al-doped 8-hydroxyquinoline

    NASA Astrophysics Data System (ADS)

    Burke, Franklyn; Abid, Mohamed; Stamenov, Plamen; Coey, J. M. D.

    2010-05-01

    Single-crystal nanowires several microns long and 100-200 nm in diameter were grown by physical vapour deposition from mixed Alq 3/γ-Al 2O 3 powder. The crystals are orthorhombic Al-doped 8-hydroxyquinoline. The molar susceptibility is -3×10 -9 at room temperature, and it shows a Curie-law upturn below about 50 K. The approach to saturation at low temperature indicates a density of S={1}/{2} defects 4×10 -4 per formula unit. Pure 8-hydroxyquinoline and aluminium (Alq 3) behave similarly. Pressed pellets exhibit much increased paramagnetic susceptibility due to iron ions scavanged from the steel die. Subsequent melting of these samples produces a ferromagnetic signal of order 0.01 A m 2 kg -1, which is attributed to metallic iron nanoclusters in the organic material.

  9. 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.

  10. The design of 8-hydroxyquinoline tetracyclic lactams as HIV-1 integrase strand transfer inhibitors.

    PubMed

    Velthuisen, Emile J; Johns, Brian A; Temelkoff, David P; Brown, Kevin W; Danehower, Susan C

    2016-07-19

    A novel series of HIV-1 integrase strand transfer inhibitors were designed using the venerable two-metal binding pharmacophore model and incorporating structural elements from two different literature scaffolds. This manuscript describes a number of 8-hydroxyquinoline tetracyclic lactams with exceptional antiviral activity against HIV-1 and little loss of potency against the IN signature resistance mutations Q148K and G140S/Q148H. PMID:27092410

  11. New approach to synthesize 8-hydroxyquinoline-based complexes with Zn2+ and their luminescent properties

    NASA Astrophysics Data System (ADS)

    Wang, Ruifang; Cao, Yali; Jia, Dianzeng; Liu, Lang; Li, Fang

    2013-12-01

    In this paper, zinc(II) bis-(8-hydroxyquinoline) dihydrate (ZnQ2·2H2O) and zinc(II) bis-(2-methyl-8-hydroxyquinoline) monohydrate (Zn(MQ)2·H2O) were successfully prepared by a room-temperature solid-state chemical reaction using zinc acetate (Zn(CH3COO)2·2H2O), 8-hydroxyquinoline (HQ) and 2-methyl-8-hydroxyquinoline (2-methyl-8-HQ) as the starting materials. The results of X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and thermal analysis (TG/DSC) demonstrated that the chemical composition of the products were ZnQ2·2H2O and Zn(MQ)2·H2O. The scanning electron microscopy (SEM) images and the transmission electron microscopy (TEM) images showed that the products ZnQ2·2H2O and Zn(MQ)2·H2O had sheet-like morphology with a thickness of about 50 nm. The UV-vis absorption spectra of ZnQ2·2H2O and Zn(MQ)2·H2O indicated that they existed charge transfer from the metal to the ligand (MLCT bands). The room-temperature photoluminescence (PL) spectra of ZnQ2·2H2O revealed that the sample possessed largely blue shift compared with the previous reports. Besides, the two complexes presented a consistent decline situation along with the decline concentration in chloroform solution, which due to solvate effect and structural similarity. The fluorescence quantum yields were measured at 36.58% and 0.07%, and the emission colors were blue-green and light-blue, respectively. The fluorescence quantum yield of ZnQ2·2H2O was higher than some reported similar structure. The method was believed to largely facilitate the fabrication and application of organometallic complex nanomaterials.

  12. Growth and spectroscopic characterization of a new organic nonlinear optical crystal—8-hydroxyquinoline

    NASA Astrophysics Data System (ADS)

    Krishnakumar, V.; Nagalakshmi, R.; Janaki, P.

    2005-04-01

    A novel organic nonlinear optical crystal 8-hydroxyquinoline having good optical quality has been grown by slow evaporation solution technique using methanol as solvent. The morphology of the grown crystals were identified by X-ray diffraction method. Solubility studies were made under various solvents and solvent mixtures at different temperatures. Functional groups present in the grown material have been identified using FTIR and FT Raman spectra. Transparency was tested using UV-vis spectrophotometer and the second harmonic generation was also verified.

  13. Novel 8-Hydroxyquinoline Derivatives as Multitarget Compounds for the Treatment of Alzheimer's Disease.

    PubMed

    Prati, Federica; Bergamini, Christian; Fato, Romana; Soukup, Ondrej; Korabecny, Jan; Andrisano, Vincenza; Bartolini, Manuela; Bolognesi, Maria Laura

    2016-06-20

    We discovered a small series of hit compounds that show multitargeting activities against key targets in Alzheimer's disease (AD). The compounds were designed by combining the structural features of the anti-AD drug donepezil with clioquinol, which is able to chelate redox-active metals, thus decreasing metal-driven oxidative phenomena and β-amyloid (Aβ)-mediated neurotoxicity. The majority of the new hybrid compounds selectively target human butyrylcholinesterase at micromolar concentrations and effectively inhibit Aβ self-aggregation. In addition, compounds 5-chloro-7-((4-(2-methoxybenzyl)piperazin-1-yl)methyl)-8-hydroxyquinoline (1 b), 7-((4-(2-methoxybenzyl)piperazin-1-yl)methyl)-8-hydroxyquinoline (2 b), and 7-(((1-benzylpiperidin-4-yl)amino)methyl)-5-chloro-8-hydroxyquinoline (3 a) are able to chelate copper(II) and zinc(II) and exert antioxidant activity in vitro. Importantly, in the case of 2 b, the multitarget profile is accompanied by high predicted blood-brain barrier permeability, low cytotoxicity in T67 cells, and acceptable toxicity in HUVEC primary cells. PMID:26880501

  14. Spin Polarization Properties of Na Doped Meridianal Tris(8-Hydroxyquinoline) Aluminum Studied by First Principles Calculations

    NASA Astrophysics Data System (ADS)

    Ren, Jun-Feng; Yuan, Xiao-Bo; Hu, Gui-Chao

    2014-04-01

    We theoretically investigate the electronic structure and spin polarization properties of Na-doped meridianal tris(8-hydroxyquinoline) aluminum (Alq3) by first principles calculations. It is found that the spin density is distributed mainly in the Alq3 part in the Alq3:Na complex. Electron charge transfer takes place from the Na atom to the Alq3 molecule, which induces asymmetric changing of the molecule bond lengths, thus the spin density distribution becomes asymmetric. Spin polarization of the complex originates from the preferable filling of the spin-split nitrogen and carbon p-orbitals because of the different bond length changes of the Alq3 molecule upon Na doping.

  15. 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

  16. Preconcentration of some metal ions with lanthanum-8-hydroxyquinoline co-precipitation system.

    PubMed

    Feist, Barbara; Mikula, Barbara

    2014-03-15

    A method of separation and preconcentration of cadmium, copper, nickel, lead and zinc at trace level using 8-hydroxyquinoline as a chelating agent and lanthanum(III) as a carrier element is proposed. The heavy metals were determined after preconcentration by inductively coupled plasma optical emission spectrometry (ICP-OES). The results were compared with those obtained using flame atomic absorption spectrometry (F-AAS). The influence of several parameters such as pH, amount of lanthanum(III) as a carrier element, amount of 8-hydroxyquinoline, duration of co-precipitation was examined. Moreover, effects of inorganic matrix on recovery of the determined elements were studied. The detection limits (DL) for ICP-OES were 0.31, 2.9, 1.4, 3.2 and 1.2 μg L(-1) for Cd, Cu, Ni, Pb and Zn, respectively, whereas for F-AAS DL were 0.63, 1.1, 3.2, 2.7 and 0.74 μg L(-1). The recovery of the method for the determined elements was better than 94% with relative standard deviation between 0.63% and 2.9%. The preconcentration factor was 60. The proposed method was successfully applied for determination of Cd, Cu, Ni, Pb, and Zn in plant materials. Accuracy of the proposed method was verified using certified reference material (NCS ZC85006 Tomato). PMID:24206710

  17. 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

  18. 5-Carboxy-8-hydroxyquinoline is a Broad Spectrum 2-Oxoglutarate Oxygenase Inhibitor which Causes Iron Translocation

    PubMed Central

    Aik, WeiShen; Che, Ka Hing; Li, Xuan Shirley; Kristensen, Jan B. L.; King, Oliver N. F.; Chan, Mun Chiang; Yeoh, Kar Kheng; Choi, Hwanho; Walport, Louise J.; Thinnes, Cyrille C.; Bush, Jacob T.; Lejeune, Clarisse; Rydzik, Anna M.; Rose, Nathan R.; Bagg, Eleanor A.; McDonough, Michael A.; Krojer, Tobias; Yue, Wyatt W.; Ng, Stanley S.; Olsen, Lars; Brennan, Paul E.; Oppermann, Udo; Muller-Knapp, Susanne; Klose, Robert J.; Ratcliffe, Peter J.; Schofield, Christopher J.; Kawamura, Akane

    2015-01-01

    2-Oxoglutarate and iron dependent oxygenases are therapeutic targets for human diseases. Using a representative 2OG oxygenase panel, we compare the inhibitory activities of 5-carboxy-8-hydroxyquinoline (IOX1) and 4-carboxy-8-hydroxyquinoline (4C8HQ) with that of two other commonly used 2OG oxygenase inhibitors, N-oxalylglycine (NOG) and 2,4-pyridinedicarboxylic acid (2,4-PDCA). The results reveal that IOX1 has a broad spectrum of activity, as demonstrated by the inhibition of transcription factor hydroxylases, representatives of all 2OG dependent histone demethylase subfamilies, nucleic acid demethylases and γ-butyrobetaine hydroxylase. Cellular assays show that, unlike NOG and 2,4-PDCA, IOX1 is active against both cytosolic and nuclear 2OG oxygenases without ester derivatisation. Unexpectedly, crystallographic studies on these oxygenases demonstrate that IOX1, but not 4C8HQ, can cause translocation of the active site metal, revealing a rare example of protein ligand-induced metal movement PMID:26682036

  19. Vinyl polymer agglomerate based transition metal cation chelating ion-exchange resin containing the 8-hydroxyquinoline functional group

    SciTech Connect

    Landing, W.M.; Haraldsson, C.; Paxeus, N.

    1986-12-01

    A simple synthetic route has been developed for the immobilization of 8-hydroxyquinoline onto Fractogel TSK, a highly porous, mechanically and chemically stable, hydrophilic organic resin gel. The product exhibits an exchange capacity comparable to the highest values reported for silica-immobilized 8-hydroxyquinoline but is more stable at high pH. The resin's selectivity and efficiency of collection of cationic metal species from freshwater and seawater were investigated. The resin was used in a column sequence to obtain concentration and speciation data for Al, Mn, Fe, Co, Cu, Zn, and Cd in an organic-rich freshwater sample.

  20. Kinetics of the complexation of ferric iron with 8-hydroxyquinoline and KELEX 100

    SciTech Connect

    Ki, K.Y; Lemert, R.M.; Chang, H.K.

    1987-01-01

    The complexation reactions of ferric iron with 8-Hydroxyquinoline and KELEX-100 in both aqueous and methanol solutions were studied by using a stopped-flow spectrophotometer. In the aqueous solutions, the observed rate law was found to be first-order with respect to both iron(III) and oxine and inverse-first-order with respect to the hydrogen ion. While in the methanol solution, the rate law was first-order with respect to iron(III) and KELEX-100. Reaction pathes with the formation of the first complex, FeAS , from either FeT or Fe(OH)S were proposed to explain the observed rate law. The activation energies were found to be 5.5 kcal/g-mole and 15 kcal/g-mole for the aqueous and methanol solutions, respectively.

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

    NASA Astrophysics Data System (ADS)

    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

    2014-01-01

    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.

  2. Synthesis, structure, and spectral and electrochemical properties of chromium(III) tris-(8-hydroxyquinolinate).

    PubMed

    Freitas, Ana R; Silva, Mónica; Ramos, M Luísa; Justino, Licínia L G; Fonseca, Sofia M; Barsan, Madalina M; Brett, Christopher M A; Silva, M Ramos; Burrows, Hugh D

    2015-07-01

    The kinetically inert chromium(III) tris-(8-hydroxyquinolinate), Crq3, has been synthesized, crystallized from 90% methanol-water, and characterized by MALDI-TOF mass spectrometry, thermogravimetry, FTIR, NMR spectroscopy, and X-ray powder diffraction. It is formed as a methanol solvate, but the solvent can be removed by heating. Large paramagnetic shifts and spectral broadening in (1)H NMR spectra indicate electron delocalization between the metal and the ligand. DFT calculations show it is present as the meridional isomer, with the HOMO largely based on one of the metal 3d orbitals and the LUMO essentially localized on the ligands. Cyclic voltammetry (CV) in acetonitrile solutions shows four oxidation peaks and two, less intense reduction waves on the first scan. The HOMO energy determined from the first oxidation peak is fairly close to that obtained by DFT, in agreement with this being mainly metal based. Although the number of peaks decreases on subsequent CV scans, the complex shows markedly enhanced electrochemical stability compared with aluminium(III) tris-(8-hydroxyquinolinate). Solution UV/visible absorption and solid diffuse reflectance spectra have a weak, long wavelength band, assigned to the metal based d-d transition, in addition to the normal, ligand based bands seen in metal quinolates. The energy of the lowest energy band is identical to the HOMO-LUMO separation obtained by cyclic voltammetry, in agreement with the above description. The compound is only weakly luminescent, in contrast to many other metal quinolates, due to the lowest energy transition being metal rather than ligand based. The potential of this compound as an electron transporting/hole blocking layer in optoelectronic devices is indicated. PMID:26030802

  3. Synthesis of highly luminescent cobalt(ii)-bis(8-hydroxyquinoline) nanosheets as isomeric aromatic amine probes

    NASA Astrophysics Data System (ADS)

    Li, Haibing; Li, Yuling

    2009-09-01

    Highly luminescent and water-soluble cobalt(ii)-bis(8-hydroxyquinoline) (CoQ2) nanosheets have been successfully synthesized via a simple, rapid sonochemical method. The water-soluble CoQ2 nanosheets were characterized by luminescence spectroscopy, UV-vis spectroscopy, FT-IR spectroscopy and transmission electron microscopy (TEM). The CoQ2 nanosheets allow highly sensitive and selective determination of p-nitroaniline via fluorescence quenching. Under optimal conditions, the relative fluorescence intensities of nanosheets decreased linearly with increasing p-nitroaniline. However, the sensitivity of CoQ2 nanosheets toward other aromatic amines including o-diaminobenzene, m-diaminobenzene, p-diaminobenzene, p-toluidine, o-nitroaniline, m-nitroaniline, p-chloroaniline and aniline is negligible. It is found that p-nitroaniline can quench the luminescence of CoQ2 nanosheets in a concentration-dependent manner that is best described by a Stern-Volmer-type equation. The possible underlying mechanism is discussed.Highly luminescent and water-soluble cobalt(ii)-bis(8-hydroxyquinoline) (CoQ2) nanosheets have been successfully synthesized via a simple, rapid sonochemical method. The water-soluble CoQ2 nanosheets were characterized by luminescence spectroscopy, UV-vis spectroscopy, FT-IR spectroscopy and transmission electron microscopy (TEM). The CoQ2 nanosheets allow highly sensitive and selective determination of p-nitroaniline via fluorescence quenching. Under optimal conditions, the relative fluorescence intensities of nanosheets decreased linearly with increasing p-nitroaniline. However, the sensitivity of CoQ2 nanosheets toward other aromatic amines including o-diaminobenzene, m-diaminobenzene, p-diaminobenzene, p-toluidine, o-nitroaniline, m-nitroaniline, p-chloroaniline and aniline is negligible. It is found that p-nitroaniline can quench the luminescence of CoQ2 nanosheets in a concentration-dependent manner that is best described by a Stern-Volmer-type equation

  4. 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

  5. Synthesis and photophysics of novel 8-hydroxyquinoline aluminum metal dye with hole transfer groups.

    PubMed

    Wang, Xiaoju; Feng, Liheng; Chen, Zhaobin

    2008-12-15

    A novel luminescent dye metal complex, (CZHQ)3Al, with 8-hydroxyquinoline aluminum and hole-transporting carbazole units was designed and synthesized. The (CZHQ)3Al optical properties were carefully investigated by UV-vis absorption and fluorescence spectra in diluent solution. The results showed that the luminescent quantum yield of (CZHQ)3Al was 0.62 in DMSO and it emitted red-light with the band gap of 2.89 eV estimated from the onset absorption. In addition, the light-emission of (CZHQ)3Al can be quenched by electron acceptor (dimethylterephalate), where the process followed the Stern-Volmer equation. However, the fluorescent intensities of (CZHQ)3Al were slowly increased with the addition of electron donor (N,N-dimethylaniline). Furthermore, the molecular interactions of (CZHQ)3Al with fullerene (C60) and carbon nanotubes (CNTs) were also respectively investigated, which indicated the metal dye can be used as new fluorescent probe. PMID:18550423

  6. DFT studies of the bonding mechanism of 8-hydroxyquinoline and derivatives on the (111) aluminum surface.

    PubMed

    Chiter, Fatah; Lacaze-Dufaure, Corinne; Tang, Hao; Pébère, Nadine

    2015-09-14

    The 8-hydroxyquinoline (8-HQ) molecule is an efficient corrosion inhibitor for aluminum and is also used in organic electronic devices. In this paper, the adsorption modes of 8-HQ and its derivatives (tautomer, dehydrogenated and hydrogenated species) on the Al(111) surface are characterized using dispersion corrected density functional theory calculations. The 8-HQ molecule is physisorbed and is chemisorbed on the aluminum surface with similar adsorption energy (-0.86 eV to -1.11 eV) and these adsorption modes are stabilized by vdW interactions. The binding of the dehydrogenated species is the strongest one (adsorption energy of -3.27 eV to -3.45 eV), followed by the tautomer molecule (-2.16 eV to -2.39 eV) and the hydrogenated molecule (-1.71 eV) that bind weaker. In all the chemisorbed configurations there is a strong electronic transfer from the Al substrate to the adsorbate (0.72 e to 2.16 e). The adsorbate is strongly distorted and its deformation energy is high (0.55 eV to 2.77 eV). The analysis of the projected density of states onto the orbitals of the molecule and the electronic density variation upon adsorption (Δρ) between the molecule and the surface account for covalent bonding. PMID:26243038

  7. 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.

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

    PubMed

    Liang, Steven H; Southon, Adam G; Fraser, Benjamin H; Krause-Heuer, Anwen M; Zhang, Bo; Shoup, Timothy M; Lewis, Rebecca; Volitakis, Irene; Han, Yifeng; Greguric, Ivan; Bush, Ashley I; Vasdev, Neil

    2015-09-10

    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 (18)F. PMID:26396692

  9. Vibrational spectroscopic investigations, ab initio and DFT studies on 7-bromo-5-chloro-8-hydroxyquinoline.

    PubMed

    Arjunan, V; Mohan, S; Ravindran, P; Mythili, C V

    2009-05-01

    The Fourier transform infrared (FTIR) and FT-Raman spectra of 7-bromo-5-chloro-8-hydroxyquinoline (BCHQ) have been measured in the range 4000-400 and 4000-100cm(-1), respectively. Complete vibrational assignment and analysis of the fundamental modes of the compound were carried out using the observed FTIR and FT-Raman data. The geometry was optimised without any symmetry constrains using the DFT/B3LYP and HF methods with 6-31G** basis set. The vibrational frequencies which were determined experimentally are compared with those obtained theoretically from ab initio HF and density functional theory (DFT) gradient calculations employing the HF/6-31G** and B3LYP/6-31G** methods for the optimised geometry of the compound. The structural parameters and normal modes of vibration obtained from HF and DFT methods are in good agreement with the experimental data. Normal coordinate analysis was also carried out with ab initio force fields utilising Wilson's FG matrix method. PMID:19112045

  10. Vibrational spectroscopic investigations, ab initio and DFT studies on 7-bromo-5-chloro-8-hydroxyquinoline

    NASA Astrophysics Data System (ADS)

    Arjunan, V.; Mohan, S.; Ravindran, P.; Mythili, C. V.

    2009-05-01

    The Fourier transform infrared (FTIR) and FT-Raman spectra of 7-bromo-5-chloro-8-hydroxyquinoline (BCHQ) have been measured in the range 4000-400 and 4000-100 cm -1, respectively. Complete vibrational assignment and analysis of the fundamental modes of the compound were carried out using the observed FTIR and FT-Raman data. The geometry was optimised without any symmetry constrains using the DFT/B3LYP and HF methods with 6-31G** basis set. The vibrational frequencies which were determined experimentally are compared with those obtained theoretically from ab initio HF and density functional theory (DFT) gradient calculations employing the HF/6-31G** and B3LYP/6-31G** methods for the optimised geometry of the compound. The structural parameters and normal modes of vibration obtained from HF and DFT methods are in good agreement with the experimental data. Normal coordinate analysis was also carried out with ab initio force fields utilising Wilson's FG matrix method.

  11. White light emission from exciplex using tris-(8-hydroxyquinoline)aluminum as chromaticity-tuning layer

    SciTech Connect

    Feng, Jing; Li, Feng; Gao, Wenbao; Liu, Shiyong; Liu, Yu; Wang, Yue

    2001-06-18

    We demonstrate efficient organic white light-emitting devices (LEDs), using N,N{prime}-diphenyl-N,N{prime}-bis(1-naphthyl){endash}(1,1{prime}-biphenyl)-4,4{prime}-diamine (NPB) as the hole-transporting layer, 1,6-bis(2-hydroxyphenyl)pyridine boron complex [(dppy)BF] as the emitting layer, tris-(8-hydroxyquinoline)aluminum (Alq) as the electron-transporting and chromaticity-tuning layer. The white light comes from exciplex emission at the solid-state interface between (dppy)BF and NPB in addition to the exciton emission from NPB and (dppy)BF, respectively. The chromaticity of white emission can be tuned by adjusting the thickness of the Alq layer. The white LEDs with an Alq thickness of 15 nm exhibit a maximum luminescence of 2000 cd/m2 and efficiency of 0.58 lm/W, and the Commission Internationale De l{close_quote}Eclairage coordinates of resulting emission vary from (0.29,0.33) to (0.31,0.35) with increasing forward bias from 10 to 25 V. The region is very close to the equienergy white point (0.33,0.33). {copyright} 2001 American Institute of Physics.

  12. Room temperature ferromagnetic properties of Al-doped bis(8-hydroxyquinoline)cobalt (Coq2) molecules

    NASA Astrophysics Data System (ADS)

    Jiang, Feng; Wei, Fangfang; Yuan, Huimin; Xie, Wanfeng; Pang, Zhiyong; Zhang, Xijian

    2015-08-01

    Room temperature ferromagnetic properties were obtained in an originally paramagnetic molecule bis(8-hydroxyquinoline)cobalt (Coq2) by doping a nonmagnetic element aluminum. The Al-doped Coq2 films with the thicknesses of about 200 nm were prepared on Si substrates by co-evaporating pure Coq2 powders (99%) and Al wires (99%) simultaneously at a base pressure of 1.9×10-4 Pa. The magnetic properties of the films were measured at different temperatures by using a Quantum Design superconducting quantum interference device (SQUID). The obtained maximum coercive field is about 250 Oe at 300 K. The electronic structures of Al-doped Coq2 were studied by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) analysis. The FTIR and XPS spectra indicate that the doped Al atoms prefer to interact with N and O atoms in Coq2 molecules. XAFS analysis shows that the Coq2 molecule does not decompose during the co-evaporating process. The ferromagnetism of the film is attributed to the interactions between Al and N p states in lowest unoccupied molecular orbitals (LUMO).

  13. Isotope effect in the spin response of aluminum tris(8-hydroxyquinoline) based devices

    NASA Astrophysics Data System (ADS)

    Nguyen, Tho D.; Basel, T. P.; Pu, Y.-J.; Li, X.-G.; Ehrenfreund, E.; Vardeny, Z. V.

    2012-06-01

    We studied the spin response of various magnetic field effects and magnetotransport in both protonated and deuterated aluminum tris(8-hydroxyquinoline) [Alq3]-based organic light emitting diodes and spin-valve devices. Both conductivity-detected magnetic resonance in diodes and magnetoresistance in spin valves show substantial isotope dependence pointing to the importance of the hyperfine interaction (HFI) in the spin response of spin ½ charge polarons in Alq3. In addition, the low field (B < 20 mT) magnetoelectroluminescence (MEL) response is also isotope sensitive, showing that HFI-induced spin mixing of polaron-pairs spin sublevels dominates this response too. However, the magnetoconductance (MC) response was found to be much less sensitive to isotope exchange at low fields, in agreement with previous studies. The disparity between the isotope sensitivity of MC and MEL responses in Alq3 indicates that the HFI in the MC response is overwhelmed by an isotope independent spin mixing mechanism. We propose that collisions of spin ½ carriers—with triplet species such as polaron pairs may be the main spin mixing mechanism in the low field MC response in Alq3 diodes.

  14. Chemistry between magnesium and multiple molecules in tris(8-hydroxyquinoline) aluminum films.

    PubMed

    Meloni, Simone; Palma, Amedeo; Schwartz, Jeffrey; Kahn, Antoine; Car, Roberto

    2003-07-01

    Metal organic contacts are at the basis of devices such as organic light emitting diodes (OLEDs). Here, we report a theoretical investigation of the chemical interaction between a Mg atom and an organic film made of tris(8-hydroxyquinoline)aluminum (Alq3) molecules. The latter is modeled either by an isolated molecule or by a bulk crystal. Using first-principles molecular dynamics for structural optimization, we find that an isolated Alq3 molecule and a Mg atom form an ion-pair. However, when the metal atom interacts with molecules in a bulk crystalline environment, we find that an organometallic complex is energetically preferred over the ion-pair. The complex formation is an effect of the environment which makes possible the interaction of the metal atom with several adjacent molecules. Here, our calculated O(1s) and N(1s) core level shifts agree well with recent experimental data on Alq3 films exposed to Mg. Our results resolve the apparent contradiction between experiment and predictions made in previous calculations in which a single Alq3 molecule was used to model a thin film. PMID:12822992

  15. 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.

  16. 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).

  17. 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

  18. TAME5OX, abiotic siderophore analogue to enterobactin involving 8-hydroxyquinoline subunits: thermodynamic and photophysical studies.

    PubMed

    Akbar, Rifat; Baral, Minati; Kanungo, B K

    2015-05-01

    The synthesis, thermodynamic and photophysical properties of trivalent metal complexes of biomimetic nonadentate analogue, 5,5'-(2-(((8-hydroxyquinolin-5-yl)methylamino)methyl)-2-methylpropane-1,3-diyl)bis(azanediyl)bis(methylene)diquinolin-8-ol (TAME5OX), have been described. Combination of absorption and emission spectrophotometry, potentiometry, electrospray mass spectrometry, IR, and theoretical investigation were used to fully characterize metal (Fe(+3), Al(+3) and Cr(+3)) chelates of TAME5OX. In solution, TAME5OX forms protonated complexes [M(H3L)](3+) below pH 3.4, which consecutively deprotonates through one to three-proton processes with rise of pH. The formation constants (Logβ11n) of neutral complexes formed at or above physiological pH, have been determined to be 30.18, 23.27 and 22.02 with pM values of 31.16, 18.07 and 18.12 for Fe(+3), Al(+3) and Cr(+3) ions, respectively, calculated at pH 7.4, indicating TAME5OX is a powerful among synthetic metal chelator. The results clearly demonstrate that the ligand in a tripodal orchestration firmly binds these ions over wide pH range and forms distorted octahedral complexes. The binding and the coordination event could be monitored from absorption and fluorescence spectroscopy. The high thermodynamic stability in water at physiological pH of ferric complex of TAME5OX indicates that these complexes are resistant to hydrolysis and therefore are well suited for the development of device for applications as probes. The ligand displays high sensitive fluorescence enhancement to Al(3+) at pH 7.4, in water. Moreover, TAME5OX can distinguish Al(3+) from Fe(3+) and Cr(3+) via two different sensing mechanisms: photoinduced electron transfer (PET) for Al(3+) and internal charge transfer (ICT) for Fe(3+) and Cr(3+). Density functional theory was employed for optimization and evaluation of vibrational modes, NBO analysis, excitation and emission properties of the different species of metal complexes observed by solution

  19. TAME5OX, abiotic siderophore analogue to enterobactin involving 8-hydroxyquinoline subunits: Thermodynamic and photophysical studies

    NASA Astrophysics Data System (ADS)

    Akbar, Rifat; Baral, Minati; Kanungo, B. K.

    2015-05-01

    The synthesis, thermodynamic and photophysical properties of trivalent metal complexes of biomimetic nonadentate analogue, 5,5‧-(2-(((8-hydroxyquinolin-5-yl)methylamino)methyl)-2-methylpropane-1,3-diyl)bis(azanediyl)bis(methylene)diquinolin-8-ol (TAME5OX), have been described. Combination of absorption and emission spectrophotometry, potentiometry, electrospray mass spectrometry, IR, and theoretical investigation were used to fully characterize metal (Fe+3, Al+3 and Cr+3) chelates of TAME5OX. In solution, TAME5OX forms protonated complexes [M(H3L)]3+ below pH 3.4, which consecutively deprotonates through one to three-proton processes with rise of pH. The formation constants (Log β11n) of neutral complexes formed at or above physiological pH, have been determined to be 30.18, 23.27 and 22.02 with pM values of 31.16, 18.07 and 18.12 for Fe+3, Al+3 and Cr+3 ions, respectively, calculated at pH 7.4, indicating TAME5OX is a powerful among synthetic metal chelator. The results clearly demonstrate that the ligand in a tripodal orchestration firmly binds these ions over wide pH range and forms distorted octahedral complexes. The binding and the coordination event could be monitored from absorption and fluorescence spectroscopy. The high thermodynamic stability in water at physiological pH of ferric complex of TAME5OX indicates that these complexes are resistant to hydrolysis and therefore are well suited for the development of device for applications as probes. The ligand displays high sensitive fluorescence enhancement to Al3+ at pH 7.4, in water. Moreover, TAME5OX can distinguish Al3+ from Fe3+ and Cr3+ via two different sensing mechanisms: photoinduced electron transfer (PET) for Al3+ and internal charge transfer (ICT) for Fe3+ and Cr3+. Density functional theory was employed for optimization and evaluation of vibrational modes, NBO analysis, excitation and emission properties of the different species of metal complexes observed by solution studies.

  20. Stable 8-hydroxyquinolinate-based podates as efficient sensitizers of lanthanide near-infrared luminescence.

    PubMed

    Comby, Steve; Imbert, Daniel; Chauvin, Anne-Sophie; Bünzli, Jean-Claude G

    2006-01-23

    New polydentate ligands (e.g., Tsox and TsoxMe) have been synthesized to take advantage of the chelating effect of bidentate 8-hydroxyquinolinate subunits connected to a N,N,N',N'-tetraaminopropyl-1,2-ethylenediamine framework and with the aim of sensitizing the NIR luminescence of Nd(III) and Yb(III) ions. Ten pK(a)'s have been determined and the interaction between the ligands and Ln(III) ions in dilute aqueous solution has been probed both by potentiometric and spectrophotometric titrations. These studies have been mostly performed with the Eu(III) ion, which is in the middle of the lanthanide series, and extended to other ions (La(III), Er(III), Lu(IIII)). Stable complexes with Ln(III) ions are formed (pLn in the range of 14-16), the four chromophoric units being coordinated to the metal center, exploiting the entropic effect generated by the anchor. The monometallic complexes [Ln(H(2)L)](3)(-) exist as the major species at physiological pH regardless of the lanthanide used. Lifetime determinations of the Nd((4)F(3/2)) and Yb((2)F(5/2)) excited levels in both H(2)O and D(2)O at buffered pH point to the absence of water molecules bound in the inner coordination sphere of the Ln(III). Photophysical properties of the free ligands and of their lanthanide complexes have been investigated in buffered aqueous solutions both at room temperature and 77 K. The low-energy triplet state makes energy transfers from the ligand to the metal ions possible; this leads to a sizable sensitization of the Nd(III)- or Yb(III)-centered luminescence ( = 0.02% and = 0.18%) for Tsox chelates. Methylation of the amide functions removes the quenching mechanism induced by the proximate N-H vibrations and increases both the lifetimes and quantum yields of the TsoxMe chelates ( = 0.04% and = 0.37%). In fact, TsoxMe yields one of the most luminescent Yb(III) compounds known in water, and this ligand appears to be suitable for the development of NIR probes for bioanalyses. PMID:16411709

  1. 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.

  2. Formation of stacked luminescent complex of 8-hydroxyquinoline molecules on hydroxyapatite coating by using cold isostatic pressing.

    PubMed

    Matsuya, Takehiko; Otsuka, Yuichi; Tagaya, Motohiro; Motozuka, Satoshi; Ohnuma, Kiyoshi; Mutoh, Yoshiharu

    2016-01-01

    Cold isostatic pressing successfully formed a chelate complex of 8-hydroxyquinoline (8 Hq) molecules on plasma-sprayed hydroxyapatite (HAp) coating by solid-state reaction. The complex emits a fluorescence peak at approximately 500 nm by UV irradiation. The red shift of the fluorescence was newly observed in the cases of highly compressed complex due to π - π stacking of aromatic ring in the molecular structure of 8 Hq. The immersed complex coating in Simulated Body Fluid (SBF) demonstrated amorphous apatite precipitation and kept its fluorescence property. PMID:26478295

  3. Bipolar resistive switching based on bis(8-hydroxyquinoline) cadmium complex: Mechanism and non-volatile memory application

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Yang, Ting; Xie, Ji-Peng; Lü, Wen-Li; Fan, Guo-Ying; Liu, Su

    2013-07-01

    Stable and persistent bipolar resistive switching was observed in an organic diode with the structure of indium-tin oxide (ITO)/bis(8-hydroxyquinoline) cadmium (Cdq2)/Al. Aggregate formation and electric field driven trapping and de-trapping of charge carriers in the aggregate states that lie in the energy gap of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the organic molecule were proposed as the mechanism of the observed bipolar resistive switching, and this was solidly supported by the results of AFM investigations. Repeatedly set, read, and reset measurements demonstrated that the device is potentially applicable in non-volatile memories.

  4. 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.

  5. One pot synthesis of functionalized SBA-15 by using an 8-hydroxyquinoline-5-sulfonamide-modified organosilane as precursor.

    PubMed

    Badiei, Alireza; Goldooz, Hassan; Ziarani, Ghodsi Mohammadi; Abbasi, Alireza

    2011-05-01

    A novel functionalized SBA-15 mesoporous material was prepared through co-condensation of tetraethylorthosilicate with an 8-hydroxyquinoline-5-sulfonamide-modified organosilane precursor in the presence of P123 as structure-directing agent. After removal of template, the obtained material was characterized by powder X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FT-IR), thermal analysis (TGA-DTA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and elemental analysis. Then, aluminum quinolate complex was attached covalently to this functionalized SBA-15 by using coordinating ability of grafted 8-HQ and its emission spectra showed a slightly blue shift in comparison with AlQ(3) complex. PMID:21349532

  6. In situ monitoring of thermal crystallization of ultrathin tris(8-hydroxyquinoline) aluminum films using surface-enhanced Raman scattering.

    PubMed

    Muraki, Naoki

    2014-01-01

    Thermal crystallization of 3, 10, and 60 nm-thick tris(8-hydroxyquinoline)aluminum (Alq3) films is studied using surface-enhanced Raman scattering with a constant heating rate. An abrupt higher frequency shift of the quinoline-stretching mode is found to be an indication of a phase transition of Alq3 molecules from amorphous to crystalline. While the 60 nm-thick film shows the same crystallization temperature as a bulk sample, the thinner films were found to have a lower crystallization temperature and slower rate of crystallization. Non-isothermal kinetics analysis is performed to quantify kinetic properties such as the Avrami exponent constants and crystallization rates of ultrathin Alq3 films. PMID:24405952

  7. Experimental and DFT studies of (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinoline: Electronic and vibrational properties

    NASA Astrophysics Data System (ADS)

    Sun, Wenqi; Yuan, Guozan; Liu, Jingxin; Ma, Li; Liu, Chengbu

    2013-04-01

    The title molecule (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinoline (DPEQ) was synthesized and characterized by FT-IR, UV-vis, NMR spectroscopy. The molecular geometry, vibrational frequencies and gauge independent atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the compound in the ground state have been calculated by using the density functional theory (DFT) method. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. The calculated results indicate that the theoretical vibrational frequencies, 1H and 13C NMR chemical shift values show good agreement with experimental data. The electronic properties like UV-vis spectral analysis and HOMO-LUMO analysis of DPEQ have been reported and compared with experimental data. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping electron density isosurface with molecular electrostatic potential (MEP).

  8. Synthesis, crystal structures and fluorescent properties of two new 7-iodo-8-hydroxyquinoline-5-sulfonic acid-containing polymers

    NASA Astrophysics Data System (ADS)

    Lu, Yongguang; Cheng, Wei; Meng, Xiangru; Hou, Hongwei

    2008-03-01

    Two new coordination polymers [Zn(IHQS)(4,4'-bipy) 1/2(H 2O) 2] n ( 1) and [Mn(IHQS)(4,4'-bipy) 1/2(H 2O) 2] n ( 2) (IHQS = 7-iodo-8-hydroxyquinoline-5-sulfonic acid) have been synthesized and characterized by single crystal X-ray diffraction. Both of them display one-dimensional chain framework in which the cage-like dimeric units formed by two metal ions, two IHQS anions and four water molecules are bridged by 4,4'-bipy. The hydrogen bonds and weak C--I···X (X = N, O, S) interactions extend the one-dimensional chains into three-dimensional supramolecular frameworks. The fluorescent properties of both polymers and IHQS were measured in solid state at room temperature. The results indicated that the emission spectra of the two polymers could be assigned to intraligand transition.

  9. 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

  10. 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

  11. 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.

  12. Thermally stimulated luminescence of naphthyl-substituted benzidine derivative and tris-8-(hydroxyquinoline) aluminum with and without metal layers

    SciTech Connect

    Forsythe, E.W.; Morton, D.C.; Gao, Y.

    1998-07-01

    Multilayer organic light emitting devices based on tris-8-(hydroxyquinoline) aluminum (Alq{sub 3}) and a naphthyl-substituted benzidine derivative (NPB) have demonstrated practical electroluminescence with a wide range of color. Trap states in these materials play an important role in the carrier transport as well as the light emission process. The authors report the first observation of thermally stimulated luminescence (TSL) from Alq{sub 3} and NPB. The TSL spectra from 8K to 300K were used to determine the trap states in Alq{sub 3} and NPB. The results for Alq{sub 3} show a significant trap distribution at 156K, which corresponds to a mean trap depth ranging from 0.18 to 0.12 eV, whereas the trap states in NPB are centered from 0.15 eV to 0.01 eV. The authors have used TSL to study the trap state properties of thin metal layers in the Alq{sub 3} films. In addition, they report photoluminescence as a function of temperature for Alq{sub 3}. TSL spectroscopy provides a technique to study the trap states in a specific layer of the device structure.

  13. Synthesis, characterization and antibacterial activity of mixed ligand dioxouranium complexes of 8-hydroxyquinoline and some amino acids.

    PubMed

    Patil, Sunil S; Shaikh, Manzoor M

    2012-01-01

    Mixed ligand complexes of dioxouranium(VI) of the type [UO2(Q)(L)-2H2O] have been synthesized using 8-hydroxyquinoline (HQ) as a primary ligand and N- and/or O- donor amino acids (HL) such as L-lysine, L-aspartic acid and L-cysteine as secondary ligands. The metal complexes have been characterized on the basis of elemental analysis, electrical conductance, room temperature magnetic susceptibility measurements, spectral and thermal studies. The electrical conductance studies of the complexes in DMF in 10(-3) M concentration indicate their non-electrolytic nature. Room temperature magnetic susceptibility measurements revealed diamagnetic nature of the complexes. Electronic absorption spectra of the complexes show intra-ligand and charge transfer transitions, respectively. Bonding of the metal ion through N- and O- donor atoms of the ligands is revealed by IR studies and the chemical environment of the protons is also confirmed by NMR studies. The thermal analysis data of the complexes indicate the presence of coordinated water molecules. The agar cup and tube dilution methods have been used to study the antibacterial activity of the complexes against the pathogenic bacteria S. aureus, C. diphtherinae, S. typhi and E. coli. PMID:22876610

  14. 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.

  15. 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

  16. Ligand Field Affected Single-Molecule Magnet Behavior of Lanthanide(III) Dinuclear Complexes with an 8-Hydroxyquinoline Schiff Base Derivative as Bridging Ligand.

    PubMed

    Wang, Wen-Min; Zhang, Hong-Xia; Wang, Shi-Yu; Shen, Hai-Yun; Gao, Hong-Ling; Cui, Jian-Zhong; Zhao, Bin

    2015-11-16

    New dinuclear lanthanide(III) complexes based on an 8-hydroxyquinoline Schiff base derivative and β-diketonate ligands, [Ln2(hfac)4(L)2] (Ln(III) = Gd (1), Tb (2), Dy (3), Ho (4), Er (5)), [Ln2(tfac)4(L)2] (Ln(III) = Gd (6), Tb (7), Dy (8), Ho (9)), and [Dy(bfac)4(L)2·C7H16] (10) (L = 2-[[(4-fluorophenyl)imino] methyl]-8-hydroxyquinoline, hfac = hexafluoroacetylacetonate, tfac = trifluoroacetylacetonate, and bfac = benzoyltrifluoroacetone), have been synthesized. The single-crystal X-ray diffraction data show that complexes 1-10 are phenoxo-O-bridged dinuclear complexes; each eight-coordinated center Ln(III) ion is in a slightly distorted dodecahedral geometry with two bidentate β-diketonate coligands and two μ2-O bridging 8-hydroxyquinoline Schiff base derivative ligands. The magnetic study reveals that 1 and 6 display cryogenic magnetic refrigeration properties, whereas complexes 3, 8, and 10 show different SMM behaviors with energy barriers of 6.77 K for 3, 19.83 K for 8, and 25.65 K for 10. Meanwhile, slow magnetic relaxation was observed in 7, while no out-of-phase alternating-current signals were found for 2. The different dynamic magnetic behaviors of two Tb2 complexes and the three Dy2 complexes mainly derive from the tiny crystal structure changes around the Ln(III) ions. It is also proved that the β-diketonate coligands can play an important role in modulating magnetic dynamics of the lanthanide 8-hydroxyquinoline Schiff base derivative system. PMID:26516660

  17. 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.

  18. 8-Hydroxyquinoline Schiff-base compounds as antioxidants and modulators of copper-mediated Aβ peptide aggregation.

    PubMed

    Gomes, Luiza M F; Vieira, Rafael P; Jones, Michael R; Wang, Michael C P; Dyrager, Christine; Souza-Fagundes, Elaine M; Da Silva, Jeferson G; Storr, Tim; Beraldo, Heloisa

    2014-10-01

    One of the hallmarks of Alzheimer's disease (AD) in the brain are amyloid-β (Aβ) plaques, and metal ions such as copper(II) and zinc(II) have been shown to play a role in the aggregation and toxicity of the Aβ peptide, the major constituent of these extracellular aggregates. Metal binding agents can promote the disaggregation of Aβ plaques, and have shown promise as AD therapeutics. Herein, we describe the syntheses and characterization of an acetohydrazone (8-H2QH), a thiosemicarbazone (8-H2QT), and a semicarbazone (8-H2QS) derived from 8-hydroxyquinoline. The three compounds are shown to be neutral at pH7.4, and are potent antioxidants as measured by a Trolox Equivalent Antioxidant Capacity (TEAC) assay. The ligands form complexes with Cu(II), 8-H2QT in a 1:1 metal:ligand ratio, and 8-H2QH and 8-H2QS in a 1:2 metal:ligand ratio. A preliminary aggregation inhibition assay using the Aβ1-40 peptide showed that 8-H2QS and 8-H2QH inhibit peptide aggregation in the presence of Cu(II). Native gel electrophoresis/Western blot and TEM images were obtained to give a more detailed picture of the extent and pathways of Aβ aggregation using the more neurotoxic Aβ1-42 in the presence and absence of Cu(II), 8-H2QH, 8-H2QS and the drug candidate PBT2. An increase in the formation of oligomeric species is evident in the presence of Cu(II). However, in the presence of ligands and Cu(II), the results match those for the peptide alone, suggesting that the ligands function by sequestering Cu(II) and limiting oligomer formation in this assay. PMID:25019963

  19. 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

  20. 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

  1. 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.

  2. Combined effects of one 8-hydroxyquinoline/picolinate and "CH"/N substitutions on the geometry, electronic structure and optical properties of mer-Alq(3).

    PubMed

    Gahungu, Godefroid; Zhang, Jingping; Ntakarutimana, Vestine; Gahungu, Nestor

    2010-01-14

    With the aim of evaluating the combined effect of one 8-hydroxyquinoline (q)/picolinate (p) and "CH"/N substitutions on the molecular geometry, electronic structure, and optical properties of tris-(8-hydroxyquinoline)aluminum [Alq(3)], the density functional theory (B3LYP) and time-dependent density functional theory (TD-B3LYP), using the 6-31G(d) and 3-21+G(d,p) basis sets were applied on Alq(3), Alq(2)p, and its "CH"/N-substitution derivatives. A comparison of the optimized ground-state (S(0)) geometries has shown that the molecular shape is conserved upon such a substitution. On the basis of the frontier molecular orbital and gap energy (E(g)) calculations, it was shown that, comparatively to the pristine Alq(2)p (and to the original parent Alq(3)), the HOMO and LUMO are stabilized, the net effect being an increasing or a decreasing E(g), depending on the position of the substituted group. The substitution of q(B) by p (from Alq(3) to Alq(2)p) was also found to induce the same feature. Starting from the S(0) and S(1) (first excited state) geometries, the effect of the substitution on the absorption (and emission) spectra was evaluated. It was found that the "CH"/N substitution in different positions on the two 8-hydroxyquinoline ligands may also constitute an efficient approach of tuning the Alq(2)p emitting color. In comparison with both Alq(3) and Alq(2)p, an important blue shift was predicted for the 5-substituted derivative, an important red shift being observed for the 4-substituted one. Also, relatively significant blue and red shifts were predicted for the 7- and 2-substituted derivatives. Finally, revisiting the correlation between the spectrum shifts and the metal-ligand bonding, our recent findings (2) were confirmed. PMID:19904976

  3. Aqueous Co(II) adsorption using 8-hydroxyquinoline anchored γ-Fe2O3@chitosan with Co(II) as imprinted ions.

    PubMed

    Hossein Beyki, Mostafa; Shemirani, Farzaneh; Shirkhodaie, Mahsa

    2016-06-01

    A novel, bio-based 8-hydroxyquinoline (8-HQ) anchored magnetic chitosan using Co(II) as imprinted ions was prepared and applied for selective removal of Co(II) from aqueous solutions. At first, γ-Fe2O3 has been synthesized by solvent free precipitation route and then combined with 8-hydroxyquinoline anchored chitosan using epichlorohydrin (EPH) as crosslinking agent. The FT- IR spectra showed that 8-HQ has been successfully anchored onto chitosan structure. Moreover, TEM analysis confirmed that the nanocomposite has core-shell structure. The experimental results showed that equilibrium time was 10min moreover, the maximum adsorption capacity of Co(II) with non-imprinted and surface imprinted polymer at pH 8 were 66.6 and 100mgg(-1), respectively. The selectivity coefficient of Co(II) ions relative to Cd(II), Ni(II) and Pb(II) were 11, 42 and 2, respectively. Prepared biosorbent represented good stability and good repeatability after three cycle of sorption and desorption using 0.5molL-(1) of HNO3 as eluent. Kinetic and thermodynamic behavior were also investigated and result showed that cobalt adsorption followed second order model and endothermic path. PMID:26944662

  4. 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

  5. Seven phenoxido-bridged complexes encapsulated by 8-hydroxyquinoline Schiff base derivatives and β-diketone ligands: single-molecule magnet, magnetic refrigeration and luminescence properties.

    PubMed

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

    2016-02-28

    Seven dinuclear complexes based on 8-hydroxyquinoline Schiff base derivatives and β-diketone ligands, [RE2(hfac)4L2] (RE = Y (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6) and Lu (7); hfac(-) = hexafluoroacetylacetonate; HL = 2-[(4-chloro-phenylimino)-methyl]-8-hydroxyquinoline), have been synthesized, and structurally and magnetically characterized. Complexes 1-7 have similar dinuclear structures, in which each RE(III) ion is eight coordinated by two L(-) and two hfac(-) ligands in a distorted dodecahedron geometry. The luminescence spectra indicate that complex 3 exhibits characteristic Tb(III) ion luminescence, while 1 and 7 show HL ligand luminescence. The magnetic studies reveal that 2 features a magnetocaloric effect with the magnetic entropy change of -ΔSm = 16.83 J kg(-1) K(-1) at 2 K for ΔH = 8 T, and 4 displays slow magnetic relaxation behavior with the anisotropic barrier of 6.7 K and pre-exponential factor τ0 = 5.3 × 10(-6) s. PMID:26792239

  6. 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.

  7. 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.

  8. Characterization of gold-thiol-8-hydroxyquinoline self-assembled monolayers for selective recognition of aluminum ion using voltammetry and electrochemical impedance spectroscopy.

    PubMed

    Shervedani, Reza Karimi; Rezvaninia, Zeinab; Sabzyan, Hassan; Boeini, Hassan Zali

    2014-05-12

    Gold electrode surface is modified via covalent attachment of a synthesized thiol functionalized with 8-hydroxyquinoline, p-((8-hydroxyquinoline)azo) benzenethiol (SHQ), for the first time. The behavior of the nanostructured electrode surface (Au-SHQ) is characterized by electrochemical techniques including cyclic and differential pulse voltammetry (CV and DPV), and electrochemical impedance spectroscopy (EIS). The modified surface is stable in a wide range of potentials and pHs. A surface pKa of 6.0±0.1 is obtained for Au-SHQ electrode using surface acid/base titration curves constructed by CV and EIS measurements as a function of pH. These results helped to determine the charge state of the surface as a function of pH. The gold modified electrode surface showed good affinity for sensing the Al(III) ion at pH 5.5. The sensing process is based on (i) accumulation and complex formation between Al(III) from the solution phase and 8HQ function on the Au electrode surface (recognition step) and (ii) monitoring the impedance of the Au-SHQ-Al(III) complex against redox reaction rate of parabenzoquinone (PBQ) (signal transduction step). The PBQ is found to be a more suitable probe for this purpose, after testing several others. Thus, the sensor was tested for quantitative determination of Al(III) from the solution phase. At the optimized conditions, a linear response, from 1.0×10(-11) to 1.2×10(-5) M Al(III) in semi-logarithmic scale, with a detection limit of 8.32×10(-12) M and mean relative standard deviation of 3.2% for n=3 at 1.0×10(-7) M Al(III) is obtained. Possible interferences from coexisting cations and anions are also studied. The results show that many ions do not interfere significantly with the sensor response for Al(III). Validity of the method and applicability of the sensor are successfully tested by determination of Al(III) in human blood serum samples. PMID:24767148

  9. 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 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. PMID:27044670

  10. 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.

  11. 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

  12. Detection of charge storage on molecular thin films of tris(8-hydroxyquinoline) aluminum (Alq3) by Kelvin force microscopy: a candidate system for high storage capacity memory cells.

    PubMed

    Paydavosi, Sarah; Aidala, Katherine E; Brown, Patrick R; Hashemi, Pouya; Supran, Geoffrey J; Osedach, Timothy P; Hoyt, Judy L; Bulović, Vladimir

    2012-03-14

    Retention and diffusion of charge in tris(8-hydroxyquinoline) aluminum (Alq(3)) molecular thin films are investigated by injecting electrons and holes via a biased conductive atomic force microscopy tip into the Alq(3) films. After the charge injection, Kelvin force microscopy measurements reveal minimal changes with time in the spatial extent of the trapped charge domains within Alq(3) films, even for high hole and electron densities of >10(12) cm(-2). We show that this finding is consistent with the very low mobility of charge carriers in Alq(3) thin films (<10(-7) cm(2)/(Vs)) and that it can benefit from the use of Alq(3) films as nanosegmented floating gates in flash memory cells. Memory capacitors using Alq(3) molecules as the floating gate are fabricated and measured, showing durability over more than 10(4) program/erase cycles and the hysteresis window of up to 7.8 V, corresponding to stored charge densities as high as 5.4 × 10(13) cm(-2). These results demonstrate the potential for use of molecular films in high storage capacity nonvolatile memory cells. PMID:22332966

  13. 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.

  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. 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

  16. 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.

  17. A Fluorescent Sensor for Al(III) and Colorimetric Sensor for Fe(III) and Fe(II) Based on a Novel 8-Hydroxyquinoline Derivative.

    PubMed

    Lashgari, Negar; Badiei, Alireza; Mohammadi Ziarani, Ghodsi

    2016-09-01

    A novel 8-hydroxyquinoline-based fluorescent and colorimetric chemosensor was designed, synthesized and fully characterized. The sensor showed high selectivity and sensitivity toward Al(3+) over other tested cations in EtOH/H2O (1:99, v/v) medium. The increase in fluorescence intensity was linearly proportional to the concentration of Al(3+) with a detection limit of 7.38 × 10(-6) M. Moreover, the sensor exhibited an obvious color change from yellow to black in the presence of Fe(2+) and Fe(3+) in EtOH/THF (99:1, v/v) solution. The absorbance changes showed a linear response to iron ions with the detection limits of 4.24 × 10(-7) M and 5.60 × 10(-7) M for Fe(2+) and Fe(3+), respectively. Thus, this chemosensor provides a novel approach for selectively recognition of Al(3+), Fe(3+) and Fe(2+) among environmentally relevant metal ions. PMID:27444961

  18. 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.

  19. 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.

  20. 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. PMID:26827866

  1. JLK1486, a Bis 8-Hydroxyquinoline-Substituted Benzylamine, Displays Cytostatic Effects in Experimental Gliomas through MyT1 and STAT1 Activation and, to a Lesser Extent, PPARγ Activation12

    PubMed Central

    Bruyère, Céline; Madonna, Sébastien; Van Goietsenoven, Gwendoline; Mathieu, Véronique; Dessolin, Jean; Kraus, Jean-Louis; Lefranc, Florence; Kiss, Robert

    2011-01-01

    Gliomas account for 5% to 7% of all solid cancers in adults and up to 30% of solid cancers in children; glioblastomas are the most malignant type of glioma and often have dismal prognoses. The alkylating agent temozolomide provides the greatest chemotherapeutic benefits currently available; however, glioblastoma patients cannot be cured. Novel drugs that efficiently combat glioblastomas are therefore of great interest. We report here that JLK1486, an 8-hydroxyquinoline-substituted benzylamine, could represent a novel chemical scaffold to reach this goal. Indeed, JLK1486 mediated anticancer activity in vivo (through intravenous as well as oral routes of administrations) in an orthotopic xenograft model and displayed efficiency similar to that of temozolomide. The therapeutic benefits of JLK1486 seem to relate to its ability to activate various transcription factors (including Myt1, STAT1, and peroxisome proliferator-activated receptor γ) in glioma cells. These transcription factors are implicated in the control of glioma cell proliferation, and the resultant global effect of their activation by JLK1486 was cytostatic, not cytotoxic. Thus, the current study opens the door for the development of novel compounds to combat glioblastoma using 8-hydroxyquinoline benzylamine analogs. PMID:21633668

  2. Analytical performance of a lab-made concomitant metal analyzer to generate volatile species of Ag, Au, Cd, Cu, Ni, Sn and Zn using 8-hydroxyquinoline as a reaction media.

    PubMed

    Villanueva-Alonso, Julia; Peña-Vázquez, Elena; Bermejo-Barrera, Pilar

    2012-10-15

    This study evaluated the main parameters affecting Ag, Au, Cd, Cu, Ni, Sn and Zn vapor generation using a lab-made concomitant metal analyzer (CMA) as a reaction chamber and gas-liquid separator. The modifier used in the reaction media was 8-hydroxyquinoline, and Inductively-Coupled Plasma Optical Emission Spectrometry was used as detection technique. The performance of the lab-made concomitant analyzer was compared with the performance of a continuous flow gas-liquid separator and of a cyclonic spray chamber. Standards were prepared in acid media and included 1 mg L(-1) of Co as a catalyzer. The optimum concentrations of the reagents in the standards were: 450 mg L(-1) of 8-hydroxyquinoline and 0.4 M nitric acid. The optimum concentration of sodium borohydride to generate the vapors was 2.25% (w/v) (prepared in 0.4% (w/v) NaOH). The volatile species were swept from the CMA to the torch by an argon flow of 0.6 mL min(-1). The use of the CMA led to an improvement of the detection limits for some elements compared to conventional nebulization: 1.1 μg L(-1) for Ag, 7.0 μg L(-1) for Au and 4.3 μg L(-1) for Sn. The limit of detection for Cu was 1.4 μg L(-1) and for Ni 22.5 μg L(-1). The direct mixing of the reagents on the spray chamber was not effective for Cd and Zn; a deviation of the linearity was observed for these elements. PMID:23141310

  3. CoFe2O4 nano-particles functionalized with 8-hydroxyquinoline for dispersive solid-phase micro-extraction and direct fluorometric monitoring of aluminum in human serum and water samples.

    PubMed

    Abdolmohammad-Zadeh, Hossein; Rahimpour, Elaheh

    2015-06-30

    A simple dispersive solid-phase micro-extraction method based on CoFe2O4 nano-particles (NPs) functionalized with 8-hydroxyquinoline (8-HQ) with the aid of sodium dodecyl sulfate (SDS) was developed for separation of Al(III) ions from aqueous solutions. Al(III) ions are separated at pH 7 via complex formation with 8-HQ using the functionalized CoFe2O4 nano-particles sol solution as a dispersed solid-phase extractor. The separated analyte is directly quantified by a spectrofluorometric method at 370nm excitation and 506nm emission wavelengths. A comparison of the fluorescence of Al(III)-8-HQ complex in bulk solution and that of Al(III) ion interacted with 8-HQ/SDS/CoFe2O4 NPs revealed a nearly 5-fold improvement in intensity. The experimental factors influencing the separation and in situ monitoring of the analyte were optimized. Under these conditions, the calibration graph was linear in the range of 0.1-300ngmL(-1) with a correlation coefficient of 0.9986. The limit of detection and limit of quantification were 0.03ngmL(-1) and 0.10ngmL(-1), respectively. The inter-day and intra-day relative standard deviations for six replicate determinations of 150ngmL(-1) Al(III) ion were 2.8% and 1.7%, respectively. The method was successfully applied to direct determine Al(III) ion in various human serum and water samples. PMID:26041520

  4. 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

  5. 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.

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

    PubMed

    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 P2(1). 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. PMID:25589396

  7. 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

  8. 8-Hydroxyquinoline-based inhibitors of the Rce1 protease disrupt Ras membrane localization in human cells.

    PubMed

    Mohammed, Idrees; Hampton, Shahienaz E; Ashall, Louise; Hildebrandt, Emily R; Kutlik, Robert A; Manandhar, Surya P; Floyd, Brandon J; Smith, Haley E; Dozier, Jonathan K; Distefano, Mark D; Schmidt, Walter K; Dore, Timothy M

    2016-01-15

    Ras converting enzyme 1 (Rce1) is an endoprotease that catalyzes processing of the C-terminus of Ras protein by removing -aaX from the CaaX motif. The activity of Rce1 is crucial for proper localization of Ras to the plasma membrane where it functions. Ras is responsible for transmitting signals related to cell proliferation, cell cycle progression, and apoptosis. The disregulation of these pathways due to constitutively active oncogenic Ras can ultimately lead to cancer. Ras, its effectors and regulators, and the enzymes that are involved in its maturation process are all targets for anti-cancer therapeutics. Key enzymes required for Ras maturation and localization are the farnesyltransferase (FTase), Rce1, and isoprenylcysteine carboxyl methyltransferase (ICMT). Among these proteins, the physiological role of Rce1 in regulating Ras and other CaaX proteins has not been fully explored. Small-molecule inhibitors of Rce1 could be useful as chemical biology tools to understand further the downstream impact of Rce1 on Ras function and serve as potential leads for cancer therapeutics. Structure-activity relationship (SAR) analysis of a previously reported Rce1 inhibitor, NSC1011, has been performed to generate a new library of Rce1 inhibitors. The new inhibitors caused a reduction in Rce1 in vitro activity, exhibited low cell toxicity, and induced mislocalization of EGFP-Ras from the plasma membrane in human colon carcinoma cells giving rise to a phenotype similar to that observed with siRNA knockdowns of Rce1 expression. Several of the new inhibitors were more effective at mislocalizing K-Ras compared to a potent farnesyltransferase inhibitor (FTI), which is significant because of the preponderance of K-Ras mutations in cancer. PMID:26706114

  9. A chelating ion exchanger for gallium recovery from alkaline solution using 5-palmitoyl-8-hydroxyquinoline immobilized on a nonpolar adsorbent

    SciTech Connect

    Filik, H.; Apak, R.

    1998-06-01

    The recently developed method of gallium recovery from alkaline solution by alkanoyl oxine/chloroform extraction has been improved by immobilizing palmitoyl oxine on hydrophobic macroporous styrene-divinylbenzene copolymer Amberlite XAD-2 and passing the GA-containing alkaline solution of pH 13.5 through the synthesized resin column. The developed column showed reasonable efficiency after successive passages, and the selectivity of Ga over Al was very high, suggesting the utilizibility of the method in Ga recovery from the basic aluminate liquor of the Bayer process. The Ga capacity of the oxine-based resin was 3.94 {micro}mol/g. Two mg Ga retained on 10 g resin could be eluted with 25 mL of 2 N HCl at a throughput rate of 2 mL/min. The developed process has prospective use in Ga separation from Al in a strongly alkaline solution.

  10. 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.

  11. Investigations into the bovine serum albumin binding and fluorescence properties of Tb (III) complex of a novel 8-hydroxyquinoline ligand

    NASA Astrophysics Data System (ADS)

    Zhao, Mingming; Tang, Ruiren; Xu, Shuai

    2015-01-01

    A novel ligand, 2-methyl-6-(8-quinolinyl)-dicarboxylate pyridine (L), and its corresponding Tb (III) complex, Na4Tb(L)2Cl4·3H2O, were successfully prepared and characterized. The luminescence spectra showed that the ligand L was an efficient sensitizer for Tb (III) luminescence. The interaction of the complex with bovine serum albumin (BSA) was investigated through fluorescence spectroscopy under physiological conditions. The Stern-Volmer analysis indicated that the fluorescence quenching was resulted from static mechanism. The binding sites (n) approximated 1.0 and this meant that interaction of Na4Tb(L)2Cl4·3H2O with BSA had single binding site. The results showed van der Waals interactions and hydrogen bonds played major roles in the binding reaction. Furthermore, circular dichroism (CD) spectra indicated that the conformation of BSA was changed.

  12. Energy alignment and trap states in dye-doped tris-8-(hydroxyquinoline) aluminum light-emitting devices

    NASA Astrophysics Data System (ADS)

    Forsythe, Eric W.; Morton, David C.; Le, Quoc T.; Yan, Li; Nuesch, F.; Tang, Ching W.; Gao, Yongli

    1999-05-01

    Thermally stimulated luminescence has used to directly measure the trap states in intrinsic Alq3 and Alq3 doped with coumarin 6. For Alq3 doped with coumarin 6, we observe an increase in the trap energy from 0.25eV for undoped Alq3 to 0.32eV for doping concentrations as high as 2 percent. The origin of these trap states may be related to the relative energy level alignment between the Alq3 host and coumarin dopant. Using UV photoemission spectroscopy, we have measured the solid state energy alignment of the highest occupied molecular orbitals between Alq3 and coumarin 6. Finally, we report I-V curves for single layer devices as a function of doping with Al/LiF top and bottom contacts. The charge transport shows the trap states induced in the Alq3 films due to the presence of the coumarin 6 molecules decrease the carrier mobility and increase the energetic disorder. These results can be directly observed from the measured I-V curves.

  13. The urinary antibiotic 5-nitro-8-hydroxyquinoline (Nitroxoline) reduces the formation and induces the dispersal of Pseudomonas aeruginosa biofilms by chelation of iron and zinc.

    PubMed

    Sobke, A; Klinger, M; Hermann, B; Sachse, S; Nietzsche, S; Makarewicz, O; Keller, P M; Pfister, W; Straube, E

    2012-11-01

    Since cations have been reported as essential regulators of biofilm, we investigated the potential of the broad-spectrum antimicrobial and cation-chelator nitroxoline as an antibiofilm agent. Biofilm mass synthesis was reduced by up to 80% at sub-MIC nitroxoline concentrations in Pseudomonas aeruginosa, and structures formed were reticulate rather than compact. In preformed biofilms, viable cell counts were reduced by 4 logs at therapeutic concentrations. Complexation of iron and zinc was demonstrated to underlie nitroxoline's potent antibiofilm activity. PMID:22926564

  14. Unravelling the role of the central metal ion in the electronic structure of tris(8-hydroxyquinoline) metal chelates: photoemission spectroscopy and hybrid functional calculations.

    PubMed

    Bisti, F; Stroppa, A; Donarelli, M; Anemone, G; Perrozzi, F; Picozzi, S; Ottaviano, L

    2012-11-29

    The electronic structures of tris(8-hydroxyquinolinato)-erbium(III) (ErQ(3)) and tris(8-hydroxyquinolinato)-aluminum(III) (AlQ(3)) have been studied by means of core level and valence band photoemission spectroscopy with the theoretical support of hybrid Heyd-Scuseria-Ernzerhof density functional theory, to investigate the role played by the central metal atom. A lower binding energy (0.2 eV and 0.3 eV, respectively) of the O 1s and N 1s core levels has been observed for ErQ(3) with respect to AlQ(3). Differences in the valence band spectra, mainly related to the first two peaks next to the highest occupied molecular orbital (HOMO), have been ascribed to an energetic shift (to 0.4 eV lower energies for ErQ(3)) of the σ molecular orbital between the oxygen atoms and the central metal atom. A lower (by 0.5 eV) ionization energy has been measured for the ErQ(3). The interpretation of these results is based on a reduced interaction between the central metal atom and the ligands in ErQ(3), with increased electronic charge around the ligands, due to the higher ionic radius and the lower electronegativity of Er with respect to Al. PMID:23106099

  15. Influence of an external magnetic field on the singlet and triplet emissions of tris-(8-hydroxyquinoline)aluminum(III) (Alq3)

    NASA Astrophysics Data System (ADS)

    Gärditz, Christoph; Mückl, Anton G.; Cölle, Michael

    2005-11-01

    The effect of a magnetic field on the triplet emission in Alq3 was investigated by measuring the delayed electroluminescence (EL) and the phosphorescence in Alq3-based organic light-emitting diodes and amorphous films, respectively. The change of the delayed EL intensity in amorphous Alq3 is explained by Merrifield's theory of mutual triplet-triplet annihilation known for molecular crystals. The intensity of the instantaneous EL shows an increase of up to +4.8% depending on the magnetic-field strength, which is due to the influence of the magnetic-field on the charge balance factor and thus on the injection of minority charge carriers.

  16. The novel mitochondrial iron chelator 5-((methylamino)methyl)-8-hydroxyquinoline protects against mitochondrial-induced oxidative damage and neuronal death.

    PubMed

    Mena, Natalia P; García-Beltrán, Olimpo; Lourido, Fernanda; Urrutia, Pamela J; Mena, Raúl; Castro-Castillo, Vicente; Cassels, Bruce K; Núñez, Marco T

    2015-08-01

    Abundant evidence indicates that iron accumulation, oxidative damage and mitochondrial dysfunction are common features of Huntington's disease, Parkinson's disease, Friedreich's ataxia and a group of disorders known as Neurodegeneration with Brain Iron Accumulation. In this study, we evaluated the effectiveness of two novel 8-OH-quinoline-based iron chelators, Q1 and Q4, to decrease mitochondrial iron accumulation and oxidative damage in cellular and animal models of PD. We found that at sub-micromolar concentrations, Q1 selectively decreased the mitochondrial iron pool and was extremely effective in protecting against rotenone-induced oxidative damage and death. Q4, in turn, preferentially chelated the cytoplasmic iron pool and presented a decreased capacity to protect against rotenone-induced oxidative damage and death. Oral administration of Q1 to mice protected substantia nigra pars compacta neurons against oxidative damage and MPTP-induced death. Taken together, our results support the concept that oral administration of Q1 is a promising therapeutic strategy for the treatment of NBIA. PMID:26051278

  17. Controlling hole-transport in aluminum tris (8-hydroxyquinoline), Alq3-based organic light emitting diodes to improve the device lifetime by an oxidized transport layer

    NASA Astrophysics Data System (ADS)

    Mathai, Mathew K.; Papadimitrakopoulos, Fotios; Hsieh, Bing R.

    2004-06-01

    A salt containing polymer, called an oxidized transport layer (OTL), was investigated for hole injection and transport into Alq3-based multilayered organic light emitting diode (OLED) devices. The OTL comprises an aryldiamine containing hole transport polymer binder with a corresponding low molecular weight radical cation salt. We demonstrate herein that the OTL behaves like a tunable resistor for holes, and its hole-transport properties can be controlled by the salt concentration and thickness of the OTL. Based on a careful analysis of the current density-voltage (J-V) device characteristics as a function of the above parameters, electron/hole currents were balanced to minimize oxidative degradation of Alq3. It was found that an OLED device (ITO/OTL/NPB/Alq3/CsF/Al) with a 5000 Å thick OTL at 5% salt concentration operated with a half-life exceeding 1000 h at a constant current of 10 mA/cm2. Similar devices with 2.5% and 10% salt doping showed an order of magnitude lower half-life attributed to unbalanced carrier concentrations. Moreover, by demonstrating that the majority of the field drops across the Alq3 layer, the doping level as opposed to OTL thickness was established as the primary contributor controlling hole transport in these OLEDs. This beneficial behavior is, however, observed only above a certain OTL thickness in the vicinity of 5000 Å.

  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. PMID:27124771

  19. 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. PMID:26575324

  20. 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...

  1. 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...

  2. Vibrational spectra of the Ga(III) complexes with oxine and clioquinol

    NASA Astrophysics Data System (ADS)

    Wagner, Claudia C.; González-Baró, Ana C.; Baran, Enrique J.

    2011-09-01

    The FTIR and FT-Raman spectra of the gallium(III) complexes of 8-hydroxyquinoline (oxine) and 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol), were recorded and briefly discussed by comparison with the spectra of the uncoordinated ligands and with some related species.

  3. 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

  4. 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.

  5. Hydroxyquinolines inhibit ribonucleic acid-dependent deoxyribonucleic acid polymerase and inactivate Rous sarcoma virus and herpes simplex virus.

    PubMed

    Rohde, W; Mikelens, P; Jackson, J; Blackman, J; Whitcher, J; Levinson, W

    1976-08-01

    8-Hydroxyquinoline and several of its derivatives inactivate the transforming ability of Rous sarcoma virus and inhibit its ribonucleic acid-dependent deoxyribonucleic acid polymerase activity. The copper complex of these metal-binding ligands is as active as the free ligand. The activity of the 8-hydroxyquinolines is approximately 50-fold more effective than another group of metal-binding compounds that we have tested, the thiosemicarbazones. In contrast to the potency of the 8-hydroxyquinolines to inactivate Rous sarcoma virus, no intracellular inhibition of transformation could be demonstrated at a concentration that did not affect the growth and appearance of the cells. Cellular deoxyribonucleic acid synthesis was inhibited to a greater extent than was ribonucleic acid or protein synthesis. The phenomenon of "concentration quenching" was observed with high concentrations of drug, causing less inhibition of deoxyribonucleic acid synthesis than was observed with lower concentrations. Herpes simplex virus type 1 was inactivated also by the 8-hydroxyquinolines and their copper complexes. No intracellular inhibition of plaque formation was observed. Treatment with 8-hydroxyquinoline sulfate had no effect on the resolution of herpetic keratitis in rabbits. Some 8-hydroxyquinolines bind to deoxyribonucleic acid in the presence of copper, a phenomenon that may be important in their antiviral activity. PMID:185949

  6. Simultaneous determination of chromium(III), aluminum(III), and iron(II) in tannery sludge acid extracts by reversed-phase high-performance liquid chromatography

    SciTech Connect

    Lopez, A.; Passino, R.; Tiravanti, G. ); Rotunno, T.; Palmisano, F.; Zambonin, P.G. )

    1991-07-01

    A new chromatographic method for the simultaneous determination of Cu(II), Zn(II), Cr(III), Al(III), and Fe(III) or Fe(II) has been developed. The method is based on precolumn formation of stable metal-8-hydroxyquinoline chelates, their separation on a C-18 reversed-phase column by HPLC, and their UV-vis detection at 400 nm. The experimental conditions giving the highest chelate yields resulted: pH 4.2; T = 90C; reaction time 30 min; reaction mixture composition methanol (66.7%)/acetonitrile (13.3%)/water (20%) (v/v/v) plus 10 mM 8-hydroxyquinoline. The mobile-phase composition giving the best resolution of Cr(III)- and Al(III)-8-hydroxyquinoline chromatographic peaks has been optimized by the simplex algorithm: acetonitrile (13.5%)/methanol (29%)/0.1 acetate buffer pH 6.8 (13.5%) (v/v/v) plus 100 mM 8-hydroxyquinoline. The method has been applied to synthetic solutions as well as, after sample pretreatment on XAD-7 resin, to real sulfuric acid extracts of tannery sludges. As for this latter matrix, additional information on Cr and Fe oxidation states has been obtained, combining the proposed method with atomic absorption spectroscopy and ion chromatography.

  7. 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…

  8. 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

  9. 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

  10. Structural aspects of adducts of N-phthaloylglycine and its derivatives

    NASA Astrophysics Data System (ADS)

    Barooah, Nilotpal; Sarma, Rupam J.; Batsanov, Andrei S.; Baruah, Jubaraj B.

    2006-06-01

    N-phthaloylglycine forms 2:1 adduct with 1,3-dihydroxybenzene and 1:2 adduct with 2-aminopyrimidine. Whereas N-phthaloylglycine form salts with 2,6-diaminopyridine and with 8-hydroxyquinoline. The 1:1 adduct of N, N'-bis(glycinyl)pyromellitic diimide with dimethylsulphoxide, 2-aminopyrimidine and 4,4'-dihydroxybiphenyl are prepared and characterised. The reaction of N, N'-bis(glycinyl)pyromellitic diimide with 2,6-diaminopyridine gives corresponding salt.

  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. Analysis of metal ions in crude oil by reversed-phase high performance liquid chromatography using short column.

    PubMed

    Salar Amoli, H; Porgam, A; Bashiri Sadr, Z; Mohanazadeh, F

    2006-06-16

    In this study a rapid, simultaneous analysis of V, Ni, Fe and Cu in crude oil was achieved by high performance liquid chromatography using 10 cm length reversed-phase C18 column. Since the amount of metal ions is at a very low level, in this work, solvent extraction of metals by a ligand such as 8-hydroxyquinoline from acidic media was investigated with some modification to previous procedures. Average extraction recoveries were 99, 85, 94 and 96 for V, Ni, Fe and Cu, respectively. The proposed method was successfully applied to the crude oil which was obtained from Koshk area in southern Iran. Fast analysis of metal ion in reversed-phase short column was achieved with methanol/water (55/45, v/v) and the detection limits measured as three times the background noise were obtained. Also it was shown that if small amount of 8-hydroxyquinoline was added to the mobile phase, the peak height and the peak symmetry were improved. A typical chromatogram for the separation of the 8-hydroxyquinoline complexes of V (V), Ni (II), Fe (III) and Cu (II) in crude oil was obtained in less than 4 min. PMID:16723133

  13. Aluminum surface corrosion and the mechanism of inhibitors using pH and metal ion selective imaging fiber bundles.

    PubMed

    Szunerits, Sabine; Walt, David R

    2002-02-15

    The localized corrosion behavior of a galvanic aluminum copper couple was investigated by in situ fluorescence imaging with a fiber-optic imaging sensor. Three different, but complementary methods were used for visualizing remote corrosion sites, mapping the topography of the metal surface, and measuring local chemical concentrations of H+, OH-, and Al3+. The first method is based on a pH-sensitive imaging fiber, where the fluorescent dye SNAFL was covalently attached to the fiber's distal end. Fluorescence images were acquired as a function of time at different areas of the galvanic couple. In a second method, the fluorescent dye morin was immobilized on the fiber-optic imaging sensor, which allowed the in situ localization of corrosion processes on pure aluminum to be visualized over time by monitoring the release of Al3+. The development of fluorescence on the aluminum surface defined the areas associated with the anodic dissolution of aluminum. We also investigated the inhibition of corrosion of pure aluminum by CeCl3 and 8-hydroxyquinoline. The decrease in current, the decrease in the number of active sites on the aluminum surface, and the faster surface passivation are all consistent indications that cerium chloride and 8-hydroxyquinoline inhibit corrosion effectively. From the number and extent of corrosion sites and the release of aluminum ions monitored with the fiber, it was shown that 8-hydroxyquinoline is a more effective inhibitor than cerium chloride. PMID:11866069

  14. 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.

  15. Electroluminescence from self-organized ``microdomes''

    NASA Astrophysics Data System (ADS)

    Karthaus, Olaf; Adachi, Chihaya; Kurimura, Shigeya; Oyamada, Takahito

    2004-06-01

    The preparation of a self-organized, microstructured organic electroluminescent device is reported. A dewetting process is used to form (sub)micrometer-sized dewetted patches ("domes") of a hole transport material (tolyl-phenyl-diaminobiphenyl, TPD) on an indium-tin-oxide electrode. The domes are regular in size and spacing. Evaporation of an electron transport material (tris-8-hydroxyquinoline aluminum, Alq3) and an Mg/Ag top electrode leads to a device with electroluminescing spots of micrometer dimensions and a spacing of a few micrometers.

  16. 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

  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. 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.

  19. 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

  20. Repulsive tip tilting as the dominant mechanism for hydrogen bond-like features in atomic force microscopy imaging

    NASA Astrophysics Data System (ADS)

    Lee, Alex J.; Sakai, Yuki; Kim, Minjung; Chelikowsky, James R.

    2016-05-01

    Experimental atomic force microscopy (AFM) studies have reported distinct features in regions with little electron density for various organic systems. These unexpected features have been proposed to be a direct visualization of intermolecular hydrogen bonding. Here, we apply a computational method using ab initio real-space pseudopotentials along with a scheme to account for tip tilting to simulate AFM images of the 8-hydroxyquinoline dimer and related systems to develop an understanding of the imaging mechanism for hydrogen bonds. We find that contrast for the observed "hydrogen bond" feature comes not from the electrostatic character of the bonds themselves but rather from repulsive tip tilting induced by neighboring electron-rich atoms.

  1. 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. PMID:24863364

  2. Magnetic field effects in singlet-polaron quenching in molecularly doped fluorescence organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Xu, Kai; Ma, Dongge

    2014-08-01

    The magnetic field effects of electroluminescence (MEL) in 4-[dicyanomethylene]-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran(DCJTB) doped tri-(8-hydroxyquinoline)-aluminum (Alq3) based organic light-emitting diodes were investigated. A linear decrease in MEL with the increase of magnetic field was observed at high magnetic field (>20 mT) in this doping devices, which has been attributed to the singlet-polaron quenching effect. It was found that the singlet-polaron quenching is magnetic field dependent. Our results showed that singlet-polaron quenching commonly exists in fluorescence OLEDs and induces the linear decrease in MEL.

  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. 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.

  5. (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.

  6. 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.

  7. Electrical properties and switching mechanisms of flexible organic-inorganic bistable devices

    NASA Astrophysics Data System (ADS)

    Onlaor, K.; Tunhoo, B.; Thiwawong, T.; Nukeaw, J.

    2013-08-01

    The electrical properties of flexible organic-inorganic bistable devices fabricated with aluminum (Al) sandwiched between tris-(8-hydroxyquinoline) aluminum (Alq3) and zinc selenide (ZnSe) layers were investigated. Current-voltage (I-V) measurements were conducted under conditions before, during, and after bending while changing the bending distance of the base plastic polyethylene terephthalate (PET) systematically. The maximum ON/OFF current ratios of the flexible bistable devices at flat and bent conditions were approximately 2.7×104 and 1.9×104, respectively. The conduction mechanisms in both ON and OFF states were analyzed by a theoretical model.

  8. 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.

  9. Laser-induced luminescence in hybrid nanofilms

    NASA Astrophysics Data System (ADS)

    Saifutyarov, R. R.; Khomyakov, A. V.; Akkuzina, A. A.; Avetisov, R. I.; Petrova, O. B.; Avetisov, I. Kh.; Kravchenko, S. V.

    2015-07-01

    Tris(8-hydroxyquinoline) boron (Bq3) was synthesized by a high-temperature exchange reaction. Bq3 powders containing various polymorphous modifications were synthesized, and their photoluminescent characteristics were analyzed. Films of Alq3/B2O3/Al hybrid materials (HMs) were deposited on glass substrates by vacuum thermal evaporation. It is shown that local heating by a diode laser (785 nm) with an intensity of 150 W/cm2 for one second causes irreversible transformation in the HM film structure. The chromaticity coordinates of the photoluminescence of laser-irradiated regions considerably differ from those of the initial HM film luminescence.

  10. 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

  11. On prediction of OH stretching frequencies in intramolecularly hydrogen bonded systems

    NASA Astrophysics Data System (ADS)

    Hansen, Poul Erik; Spanget-Larsen, Jens

    2012-06-01

    OH stretching frequencies are investigated for a series of non-tautomerizing systems with intramolecular hydrogen bonds. Effective OH stretching wavenumbers are predicted by the application of empirical correlation procedures based on the results of B3LYP/6-31G(d) theoretical calculations in the harmonic and PT2 anharmonic approximations, as well as on experimental NMR parameters, i.e., proton chemical shifts (δH) and two-bond deuterium isotope effects on 13C chemical shifts (2ΔCOD). The procedures are applied in a discussion of the spectra of 2,6-dihydroxy-4-methylbenzaldehyde and 8-hydroxyquinoline N-oxide. The spectrum of the former displays a broad, composite band between 3500 and 2500 cm-1 which can be assigned to overlapping monomer and dimer contributions. In the latter case, the results support a reassignment of the OH stretching band of 8-hydroxyquinoline N-oxide; the reassignment is supported by correlation with the IR spectra of a series of substituted derivatives.

  12. Process for the extended use of strip acid employed in the reclamation of battery acid fluid from expanded lead-acid batteries

    SciTech Connect

    Spitz, R.A.; Bricker, M.

    1991-04-23

    This patent describes a method for recycling contaminated sulfuric acid from lead acid batteries to reclaimed sulfuric acid for reuse in the batteries by removing contaminating iron impurities. It includes diluting the contaminated sulfuric acid to a concentration between 150 and 230 grams per liter; filtering the sulfuric acid through a first filter means to remove solid impurities; oxidizing the sulfuric acid to assure that the iron contaminants are substantially in a ferric form; removing the iron contaminants from the sulfuric acid through liquid-liquid extracting using an extraction agent comprising mixture of a mono- or di-alkyl phosphoric acid and a metal chelation collector selected from the group consisting of a 8- hydroxyquinoline substituted in the No. 7 position with a long chain aliphatic hydrocarbon radical and an oil-soluble 2-hydroxy benzophenoneoxime, a modifier which maintains solubility of the phosphoric acid and the metal chelation collector and enhances phase disengagement, and a water immiscible carrier, the molar ratio of the 8-hydroxyquinoline and the phosphoric acid being between 1:1::1:4, respectively; wherein the ratio of extraction agent to water immiscible carrier is greater than 10:90; the extraction performed at a volumetric ratio between 4:1::1:4, and repeated until the contaminating iron impurities are substantially reduced.

  13. 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

  14. New fluorescence reactions in DNA cytochemistry. 2. Microscopic and spectroscopic studies on fluorescent aluminum complexes

    SciTech Connect

    Del Castillo, P.; Llorente, A.R.; Gomez, A.; Gosalvez, J.; Goyanes, V.J.; Stockert, J.C. )

    1990-02-01

    Metal-dye complexes are widely applied in light microscopic techniques for chromatin staining (e.g., hematoxylin and carmine), but fluorescent complexes between phosphate-binding cations and suitable ligands have been little used. Preformed and postformed Al complexes with different anionic dyes induced strong and selective fluorescence reactions in nuclei from chicken blood smears, frozen sections, paraffin-embedded sections and Epon-embedded sections of mouse and rat tissues, mitotic chromosomes, meiotic chromosomes and kinetoplasts of Trypanosoma cruzi epimastigotes. The DNA-dependent fluorescence of these structures showed a very low fading rate. The emission colors were related to the ligand. The most suitable compounds for forming fluorescent Al chelates were 8-hydroxyquinoline, morin, nuclear fast red and purpurin. Staining with diluted carmine solutions and InCl3 mordanting, followed by 8-hydroxyquinoline, also induced chromatin fluorescence. After treating isolated mouse chromosomes with the preformed complex Al-nuclear fast red, x-ray microanalysis indicated a P:Al:dye binding ratio of about 40:15:1. The selectivity, stability and easy formation of these fluorescent Al complexes are obvious advantages for their use as new cytochemical probes in cytologic studies.

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

    PubMed

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

    2014-01-01

    Novel mixed ligand bivalent copper complexes [Cu. L. A. ClO 4 ] 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)/2,2(1)-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

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. Control of catalytic hydrotreating selectivity with ammonia

    SciTech Connect

    Satterfield, C.N.; Lee, Chung M.

    1990-01-01

    Research continued on catalytic hydrotreating selectivity with ammonia. In the last quarterly we presented results of the hydrodenitrogenation (HDN) of 8-OH quinoline 8-hydroxyquinoline (8HQ) and showed that three routes are involved beyond those encountered in the HDN of quinoline. We have now developed a new kinetic model for this reaction, which is adapted from Satterfield and Smith (1986) as applied to quinoline. Some basic assumptions of the model include: (1) the Langmuir-Hinshelwood kinetic model with all sites occupied is applicable, (2) the dehydrogenation rates of 5,6,7,8-tetrahydroquinoline (BzTHQ) and decahydroquinoline (DHQ) to quinoline (Q) and 1,2,3,4-tetrahydroquinoline (PyTHQ) are small enough to be neglected, and (3) the clean hydrocarbon products are not appreciably adsorbed. 2 refs., 3 figs., 1 tab.

  2. Dendrite-like Co3O4 nanostructure and its applications in sensors, supercapacitors and catalysis.

    PubMed

    Pang, Huan; Gao, Feng; Chen, Qun; Liu, Rongmei; Lu, Qingyi

    2012-05-21

    Dendrite-like Co(3)O(4) nanostructure, made up of many nanorods with diameters of 15-20 nm and lengths of 2-3 μm, has been successfully prepared by calcining the corresponding nanostructured Co-8-hydroxyquinoline coordination precursor in air. The Co(3)O(4) nanostructure was evaluated as an electrochemical sensor for H(2)O(2) detection and the results reveal that it has good linear dependence and high sensitivity to H(2)O(2) concentration changes. As an electrode material of a supercapacitor, it was found that the nanostructured Co(3)O(4) electrode exhibits high specific capacitance and long cycle life. The Co(3)O(4) nanostructure also has good catalytic properties and is steadily active for CO oxidation, giving 100% CO conversion at low temperatures. The multifunctional Co(3)O(4) nanostructure would be a promising functional nanomaterial applied in multi industrialized fields. PMID:22453646

  3. Properties of 4-dicyanomethylene-2-methyl-6-(p-dimethyl-aminostyryl)-4H-pyran-doped Alq layers as optically pumped lasers

    NASA Astrophysics Data System (ADS)

    Jakabovič, J.; Lengyel, O.; Kováč, J.; Wong, T. C.; Lee, C. S.; Lee, S. T.

    2003-08-01

    The optical properties of tris-(8-hydroxyquinoline) aluminum (Alq) doped with 4-dicyanomethylene-2-methyl-6-(p-dimethyl-aminostyryl)-4H-pyran (DCM) in solutions and in solid films were studied by measuring the steady-state excitation and spontaneous emission spectra. The emission peak in the solid films shifted from 628 to 659 nm as the doping concentration of DCM changed from 0.9% to 11%. The optically pumped waveguide lasers were fabricated by coevaporation of Alq films with 1.3 wt % DCM onto gallium arsenide (GaAs) substrates using silicon dioxide (SiO2) and magnesium fluoride (MgF2) as cladding layers. Both types of waveguide laser structures showed optical confinement and simulated emission at a threshold pumping energy near 1.4 μJ. The result suggests a thin MgF2 may be used as a confinement layer that has the advantage of preparation by low-temperature evaporation.

  4. Tip relaxation in atomic force microscopy imaging simulations to resolve intermolecular bonds

    NASA Astrophysics Data System (ADS)

    Lee, Alex; Sakai, Yuki; Chelikowsky, Jim

    Experimental noncontact atomic force microscopy (AFM) studies have reported distinct lines in regions with no electron density for a variety of systems. The appearance of these lines is unexpected because Pauli repulsion is thought to be the dominant factor in the AFM imaging mechanism. These lines have been proposed to represent intermolecular bonding. Recent theoretical studies have shown that accounting for tip probe relaxation can sharpen images and highlight features that make simulations more comparable to experiment. We will apply a similar tip relaxation scheme to our computational method-which uses an ab initio real-space pseudopotential formalism with frozen density embedding theory added-to the study of dibenzo[a,h]thianthrene and an 8-hydroxyquinoline dimer to develop our interpretation of imaged intermolecular bonds. Work is supported by the DOE under DOE/DE-FG02-06ER46286 and by the Welch Foundation under Grant F-1837. Computational resources were provided by NERSC and XSEDE.

  5. Excitonic singlet-triplet ratios in molecular and polymeric organic materials

    NASA Astrophysics Data System (ADS)

    Baldo, Marc; Agashe, Shashank; Forrest, Stephen

    2002-03-01

    A simple technique is described for the determination of the internal efficiency and excitonic singlet-triplet formation statistics of electroluminescent organic thin films. The internal efficiency is measured by optically exciting a luminescent film within an electroluminescent device under reverse bias. This gives minimum singlet fractions of (0.20+/-0.03) and (0.19+/-0.04) for tris(8-hydroxyquinoline) aluminum (Alq3) and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), respectively. These results are discussed in terms of the current understanding of exciton formation within organic materials. We also present measurements of the out-coupling fraction, or the fraction of photons emitted in the forward direction, as a function of the position of the emitting layer within a microcavity.

  6. Nanomolar colorimetric quantitative detection of Fe(3+) and PPi with high selectivity.

    PubMed

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

    2016-04-15

    A novel rhodamine and 8-hydroxyquinoline-based derivative was synthesized, which is shown to act as a colorimetric chemosensor for Fe(3+) 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 (<1min). Fe(3+) can be detected quantitatively in the concentration range from 6.7 to 16μM and the detection limit (LOD) on UV-vis response of the sensor can be as low as 15nM. The 'in situ' prepared Fe(3+) complex (1⋅Fe) showed high selectivity toward PPi against many common anions, and sensitivity (the LOD can be as low as 71nM). In addition, both the chemosensor and the 'in situ' prepared Fe(3+) complex are reusable for the detection of Fe(3+) and PPi respectively. PMID:26878355

  7. Unusual Cyclodextrin Derivatives as a New Avenue to Modulate Self- and Metal-Induced Aβ Aggregation.

    PubMed

    Oliveri, Valentina; Bellia, Francesco; Pietropaolo, Adriana; Vecchio, Graziella

    2015-09-28

    Mounting evidence suggests an important role of cyclodextrins in providing protection in neurodegenerative disorders. Metal dyshomeostasis is reported to be a pathogenic factor in neurodegeneration because it could be responsible for damage involving oxidative stress and protein aggregation. As such, metal ions represent an effective target. To improve the metal-binding ability of cyclodextrin, we synthesized three new 8-hydroxyquinoline-cyclodextrin conjugates with difunctionalized cyclodextrins. In particular, the 3-difunctionalized regioisomer represents the first example of cyclodextrin with two pendants at the secondary rim, resulting in a promising compound. The derivatives have significant antioxidant capacity and the powerful activity in inhibiting self-induced amyloid-β aggregation seems to be led by synergistic effects of both cyclodextrin and hydroxyquinoline. Moreover, the derivatives are also able to complex metal ions and to inhibit metal-induced protein aggregation. Therefore, these compounds could have potential as therapeutic agents in diseases related to protein aggregation and metal dyshomeostasis. PMID:26298549

  8. 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.

  9. Metal ions, Alzheimer's disease and chelation therapy.

    PubMed

    Budimir, Ana

    2011-03-01

    In the last few years, various studies have been providing evidence that metal ions are critically involved in the pathogenesis of major neurological diseases (Alzheimer, Parkinson). Metal ion chelators have been suggested as potential therapies for diseases involving metal ion imbalance. Neurodegeneration is an excellent target for exploiting the metal chelator approach to therapeutics. In contrast to the direct chelation approach in metal ion overload disorders, in neurodegeneration the goal seems to be a better and subtle modulation of metal ion homeostasis, aimed at restoring ionic balance. Thus, moderate chelators able to coordinate deleterious metals without disturbing metal homeostasis are needed. To date, several chelating agents have been investigated for their potential to treat neurodegeneration, and a series of 8-hydroxyquinoline analogues showed the greatest potential for the treatment of neurodegenerative diseases. PMID:21406339

  10. Derivative analysis of potentiometric titration data to obtain protonation constants

    SciTech Connect

    Chen, J.F.; Xia, Y.X.; Choppin, G.R.

    1996-11-15

    A methodology is described to calibrate glass electrodes and to analyze potentiometric titration data to calculate protonation constants. The analysis uses the variation of dV/dpH with titrant addition in terms of two physical parameters which involve the concentrations of H{sup +}, OH{sup -}, and H{sub m}A. The data for titration of acetic acid and 8-hydroxyquinoline in 0.10-5.0 m NaCl media are analyzed by this method to obtain the stoichiometric protonation constants of the acids, the ionization constants of water, and the parameters s and b in the pH electrode calibration equation, pcH = spH{sub m} + b, where pcH = -log[H{sup +}], pH{sub m} is the pH meter reading. 31 refs., 3 figs., 6 tabs.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    `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) (Alq3) 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:Alq3 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.

  13. Low driving voltage and high stability organic light-emitting diodes with rhenium oxide-doped hole transporting layer

    NASA Astrophysics Data System (ADS)

    Leem, Dong-Seok; Park, Hyung-Dol; Kang, Jae-Wook; Lee, Jae-Hyun; Kim, Ji Whan; Kim, Jang-Joo

    2007-07-01

    The authors report a promising metal oxide-doped hole transporting layer (HTL) of rhenium oxide (ReO3)-doped N ,N'-diphenyl-N ,N'-bis (1,1'-biphenyl)-4,4'-diamine (NPB). The tris(8-hydroxyquinoline) aluminum-based organic light-emitting diodes with ReO3-doped NPB HTL exhibit driving voltage of 5.2-5.4V and power efficiency of 2.2-2.3lm/W at 20mA/cm2, which is significantly improved compared to those (7.1V and 2.0lm/W, respectively) obtained from the devices with undoped NPB. Furthermore, the device with ReO3-doped NPB layer reveals the prolonged lifetime than that with undoped NPB. Details of ReO3 doping effects are described based on the UV-Vis absorption spectra and characteristics of hole-only devices.

  14. Substrate temperature controls molecular orientation in two-component vapor-deposited glasses.

    PubMed

    Jiang, J; Walters, D M; Zhou, D; Ediger, M D

    2016-04-01

    Vapor-deposited glasses can be anisotropic and molecular orientation is important for organic electronics applications. In organic light emitting diodes (OLEDs), for example, the orientation of dye molecules in two-component emitting layers significantly influences emission efficiency. Here we investigate how substrate temperature during vapor deposition influences the orientation of dye molecules in a model two-component system. We determine the average orientation of a linear blue light emitter 1,4-di-[4-(N,N-diphenyl)amino]styryl-benzene (DSA-Ph) in mixtures with aluminum-tris(8-hydroxyquinoline) (Alq3) by spectroscopic ellipsometry and IR dichroism. We find that molecular orientation is controlled by the ratio of the substrate temperature during deposition and the glass transition temperature of the mixture. These findings extend recent results for single component vapor-deposited glasses and suggest that, during vapor deposition, surface mobility allows partial equilibration towards orientations preferred at the free surface of the equilibrium liquid. PMID:26922903

  15. Comparative study of metal or oxide capped indium-tin oxide anodes for organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Qiu, Chengfeng; Xie, Zhilang; Chen, Haiying; Wong, Man; Kwok, Hoi Sing

    2003-03-01

    Indium-tin oxide capped with a variety of nanometer-thick metal or oxide buffer layers has been investigated as anodes in organic light-emitting diodes based on N,N'-diphenyl-N,N' bis(3-methyl-phenyl-1,1'-biphenyl-4,4'-diamine/tris-8-hydroxyquinoline aluminum. Although high work-function metal buffer layers led to enhancement in hole-injection efficiency, none of the metals investigated gave rise to improvement in current or power efficiency. On the other hand, diodes with some of the oxide buffer layers exhibited improvement not only in hole injection but also in power efficiency. In particular, when 1 nm thick praseodymium oxide was used as the cap layer, more than double the power efficiency was obtained.

  16. Role of ultrathin Alq3 and LiF layers in conjugated polymer light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Deng, X. Y.; Tong, S. W.; Hung, L. S.; Mo, Y. Q.; Cao, Y.

    2003-05-01

    We report that an ultrathin layer of tris-(8-hydroxyquinoline) aluminum (Alq3) interposed between a bilayer cathode of LiF/Al and an emissive layer can significantly improve electroluminescence efficiency in a polymer light-emitting device (PLED). At a current density of 35 mA/cm2, a poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenyl-enevinylene] (MEH-PPV)-based PLED with a cathode of Alq3/LiF/Al has a quantum efficiency of 2.5%, considerably higher than that of a MEH-PPV-based PLED with a bare Al or a LiF/Al cathode. Interfacial characteristics of MEH-PPV/LiF/Al and MEH-PPV/Alq3/LiF/Al were investigated by photoelectron spectroscopy, and the results were used to explain the difference in device performance.

  17. 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.

  18. Exploiting Innate Immune Cell Activation of a Copper-Dependent Antimicrobial Agent during Infection

    PubMed Central

    Festa, Richard A.; Helsel, Marian E.; Franz, Katherine J.; Thiele, Dennis J.

    2014-01-01

    SUMMARY Recalcitrant microbial infections demand new therapeutic options. Here we present an approach that exploits two prongs of the host immune cell antimicrobial response: the oxidative burst and the compartmentalization of copper (Cu) within phagolysosomes. The prochelator QBP is a nontoxic protected form of 8-hydroxyquinoline (8HQ) in which a pinanediol boronic ester blocks metal ion coordination by 8HQ. QBP is deprotected via reactive oxygen species produced by activated macrophages, creating 8HQ and eliciting Cu-dependent killing of the fungal pathogen Cryptococcus neoformans in vitro and in mouse pulmonary infection. 8HQ ionophoric activity increases intracellular Cu, overwhelming the Cu-resistance mechanisms of C. neoformans to elicit fungal killing. The Cu-dependent antimicrobial activity of 8HQ against a spectrum of microbial pathogens suggests that this strategy may have broad utility. The conditional activation of Cu ionophores by innate immune cells intensifies the hostile antimicrobial environment and represents a promising approach to combat infectious disease. PMID:25088681

  19. 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.

  20. 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

  1. 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.

  2. Recovery of gallium(III) from strongly alkaline media using a Kelex-100-loaded ion-exchange resin

    SciTech Connect

    Nakayama, Morio; Egawa, Hiroaki

    1997-10-01

    Kelex-100 [7-(4-ethyl-1-methyloctyl)-8-hydroxyquinoline] is an important liquid-chelating ion exchanger in hydrometallurgy and a highly selective extractant for gallium (Ga). In this study, Kelex-100-loaded ion-exchange resins were prepared for the recovery of Ga(III) from sodium aluminate solutions (Bayer solution) used in the Bayer process. When macroporous type ion-exchange resins were used as polymer matrices for loading Kelex-100, the physical pore structure and the ion-exchange group significantly affected the adsorption of Ga(III) from strongly alkaline media on the Kelex-100-loaded resin. In particular, the Kelex-100-loaded carboxylic type resin having a macroporous structure showed a high capacity for Ga(III) in concentrated NaOH solution and effectively recovered Ga(III) from the Bayer solution containing large amounts of aluminum(III).

  3. “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

  4. 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.

  5. 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.

  6. 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. PMID:26725969

  7. The charge-trapping and triplet-triplet annihilation processes in organic light-emitting diodes: A duty cycle dependence study on magneto-electroluminescence

    NASA Astrophysics Data System (ADS)

    Peng, Qiming; Chen, Ping; Li, Feng

    2013-01-01

    We studied the magneto-electroluminescence (MEL) in tri-(8-hydroxyquinoline)-aluminum (Alq3)-based organic light-emitting devices through both steady-state and transient methods. As the magnetic field increases, the MEL exhibits a rapid rise, followed by the saturation tendency at all voltages in the steady-state measurement, but in the transient measurement it first increases to a maximum and then decreases to negative values when the driving voltages are higher than 8V. Furthermore, we found that the MEL strongly depends on the duty cycle of the pulse voltage. Finally, by employing the triplet-triplet annihilation model combined with the charge trapping effects, we explained the duty cycle dependence of MELs.

  8. Heterocyclic Aromatic N-Oxidation in the Biosynthesis of Phenazine Antibiotics from Lysobacter antibioticus.

    PubMed

    Zhao, Yangyang; Qian, Guoliang; Ye, Yonghao; Wright, Stephen; Chen, Haotong; Shen, Yuemao; Liu, Fengquan; Du, Liangcheng

    2016-05-20

    Heterocyclic aromatic N-oxides often have potent biological activities, but the mechanism for aromatic N-oxidation is unclear. Six phenazine antibiotics were isolated from Lysobacter antibioticus OH13. A 10 gene cluster was identified for phenazine biosynthesis. Mutation of LaPhzNO1 abolished all N-oxides, while non-oxides markedly increased. LaPhzNO1 is homologous to Baeyer-Villiger flavoproteins but was shown to catazlye phenazine N-oxidation. LaPhzNO1 and LaPhzS together converted phenazine 1,6-dicarboxylic acid to 1,6-dihydroxyphenazine N5,N10-dioxide. LaPhzNO1 also catalyzed N-oxidation of 8-hydroxyquinoline. PMID:27145204

  9. 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.

  10. Surface complexation reaction for phase transfer of hydrophobic quantum dot from nonpolar to polar medium.

    PubMed

    Bhandari, Satyapriya; Roy, Shilaj; Pramanik, Sabyasachi; Chattopadhyay, Arun

    2014-09-01

    Chemical reaction between oleate-capped Zn(x)Cd(1-x)S quantum dots (Qdots) and 8-hydroxyquinoline (HQ) led to formation of a surface complex, which was accompanied by transfer of hydrophobic Qdots from nonpolar (hexane) to polar (water) medium with high efficiency. The stability of the complex on the surface was achieved via involvement of dangling sulfide bonds. Moreover, the transferred hydrophilic Qdots--herein called as quantum dot complex (QDC)--exhibited new and superior optical properties in comparison to bare inorganic complexes with retention of the dimension and core structure of the Qdots. Finally, the new and superior optical properties of water-soluble QDC make them potentially useful for biological--in addition to light emitting device (LED)--applications. PMID:25133937

  11. 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.

  12. Time-resolved spin-dependent processes in magnetic field effects in organic semiconductors

    NASA Astrophysics Data System (ADS)

    Peng, Qiming; Li, Xianjie; Li, Feng

    2012-12-01

    We investigated the time-resolved magnetic field effects (MFEs) in tri-(8-hydroxyquinoline)-aluminum (Alq3) based organic light-emitting diodes (OLEDs) through the transient electroluminescence (EL) method. The values of magneto-electroluminescence (MEL) decrease with the time, and the decreasing slope is proportional to the driving voltage. Specifically, negative MELs are seen when the driving voltage is high enough (V > 11 V). We propose a model to elucidate the spin-dependent processes and theoretically simulate the time-resolved MELs. In particular, this dynamic analysis of time-resolved MELs reveals that the intersystem crossing between singlet and triplet electron-hole pairs and the triplet-triplet annihilation are responsible for the time-resolved MELs at the beginning and enduring periods of the pulse, respectively.

  13. Comparison of two lab-made spray chambers based on MSIS™ for simultaneous metal determination using vapor generation-inductively coupled plasma optical emission spectroscopy.

    PubMed

    Fuentes-Cid, A; Villanueva-Alonso, J; Peña-Vázquez, E; Bermejo-Barrera, P

    2012-10-24

    The objective of this study is to evaluate the performance of two lab-made systems based on the Multimode Introduction System (MSIS™) and the modified MSIS™, to generate and introduce vapors of Ag, Cu, Cd, Cu, Ni, Sn, Zn, and also Au in the ICP torch. An univariate procedure was used to select the optimized working conditions (Ar flow, sample, reductant and waste flows, and reagent concentrations). Optimum conditions for working with modified MSIS were: nitric acid concentration 0.35 M, 8-hydroxyquinoline concentration: 40 mg L(-1), sodium borohydride concentration: 1.75% (w/v)+0.4% (w/v) NaOH, argon purge flow to sweep the vapors to the torch: 1.2 L min(-1), sample flow and sodium borohydride flows: 2.3 L min(-1); waste flow: 7.7 mL min(-1). For the optimum working conditions for lab-made MSIS in dual mode the concentration of 8-hydroxyquinoline was 225 mg L(-1), the Ar purge flow was 0.75 L min(-1), and the conventional nebulization flow was 2.3 L min(-1). The sensitivity obtained was higher using the lab-made MSIS than using the lab-made modified MSIS or a forced outlet gas-liquid separator. The limits of detection were better for Au, Cd, Sn than those obtained using conventional nebulization; the measurements were precise (RSDs≤5% in dual mode) and a good accuracy was obtained in the determination of Cd, Cu, Ni and Zn in a wastewater reference material using aqueous calibration and the lab-made MSIS in dual mode. PMID:23036464

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    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.

  15. 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

  16. Synthesis of new pyridinoazacrown ethers containing aromatic and heteroaromatic proton ionizable substituents

    SciTech Connect

    Bordunov, A.V.; Hellier, P.C.; Bradshaw, J.S.

    1995-09-22

    Methods for the synthesis of pyridinocrowns functionalized with various proton ionizable groups have been elaborated. Sixteen new ligands containing pyridine rings as part of the macrocycle or as a side arm have been prepared. Different interactive abilities of the OH and NH functions of 3,9-dioxa-6-azaundecane-1,11-diol (3) in strong base allowed the synthesis of pyridinoazacrowns 1 and 2 by cyclization with 2,6-bis((tosyloxy)methyl)pyridine (4) and THP- protected 4-hydroxy-2,6-bis((tosyloxy)methyl)pyridine (5). Pyridinoazacrown 1 was functionalized with different proton ionizable side arms by treatment first with formaldehyde in methanol to form the N-methoxymethyl derivative 6 and then treating 6 with 5-chloro-8-hydroxyquinoline or the appropriate substituted phenol. Pyridinoaza-18-crown-6 ligands containing p-methylphenol (7), p-methoxphenol (8), p-chlorophenol (9), p-fluorophenol (10), p-cyanophenol (11), 2-formyl-4-bromophenol (12), or 5-chloro-8-hydroxyquinoline (13) groups were prepared by this process. Pyridinoazacrowns 1 and 2 were alkylated with 2-hydroxy-5-nitrobenzyl chloride or 5-chloro-8-methoxy-2-(bromomethyl)quinoline followed by removal of the protecting groups to form p-nitrophenol- and 5-chloro-8-hydroxy-2-quinolinyl-substituted ligands (16, 18, and 21). Macrocycles 22 and 23 containing proton ionizable triazole and phenol functions inside the macrocyclic cavity and a pyridine side arm were prepared by cyclization of the appropriate dihalide with 6-(2{prime}-pyridylmethyl)-3,9-dioxa-6-azaundecane-1,11-diol followed by cleavage of the THP or methoxy protecting groups. Preliminary complexation data show that the phenol-substituted pyridinoaza-18-crown-6 ligands form strong complexes with various metal cations and exhibit high selectivity toward Ag{sup +}. Macrocycle 16 containing a p-nitrophenol substituent formed a complex with benzylamine. The crystal structures for 16 and its benzylamine complex are also given here.

  17. 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).

  18. Radiolytic and cellular reduction of a novel hypoxia-activated cobalt(III) prodrug of a chloromethylbenzindoline DNA minor groove alkylator.

    PubMed

    Ahn, G-One; Botting, K Jane; Patterson, Adam V; Ware, David C; Tercel, Moana; Wilson, William R

    2006-06-14

    Metabolic reduction can be used to activate prodrugs in hypoxic regions of tumours, but reduction by ionising radiation is also theoretically attractive. Previously, we showed that a cobalt(III) complex containing 8-hydroxyquinoline (8-HQ) and cyclen ligands releases 8-HQ efficiently on irradiation in hypoxic solutions [Ahn G-O, Ware DC, Denny WA, Wilson WR. Optimization of the auxiliary ligand shell of cobalt(III)(8-hydroxyquinoline) complexes as model hypoxia-selective radiation-activated prodrugs. Radiat Res 2004;162:315-25]. Here we investigate an analogous Co(III) complex containing the potent DNA minor groove alkylator azachloromethylbenzindoline (azaCBI, 1) to determine whether it releases 1 on radiolytic and/or enzymatic reduction under hypoxia. Monitoring by HPLC, the azaCBI ligand in the Co(III)(cyclen)(azaCBI) complex (2) slowly hydrolysed in aqueous solution, in contrast to the free ligand 1 which readily converted to its reactive cyclopropyl form. Irradiation of 2 (30-50 microM) in hypoxic solutions released 1 with yields of 0.57 micromol/J in formate buffer and 0.13 micromol/J in human plasma. Using bioassay methods, cytotoxic activation by irradiation of 2 at 1 microM in hypoxic plasma was readily detectable at clinically relevant doses (> or = 1 Gy), with a estimated yield of 1 of 0.075 micromol/J. Release of 1 from 2 was also observed in hypoxic HT29 cultures without radiation, with subsequent conversion of 1 to its O-glucuronide. Surprisingly, overexpression of human cytochrome P450 reductase in A549 cells did not increase the rate of metabolic reduction of 2, suggesting that other reductases and/or non-enzymatic reductants are responsible. Thus the cobalt(III) complex 2 is a promising prodrug capable of being activated to release a very potent cytotoxin when reduced by either ionising radiation or cells under hypoxic conditions. PMID:16620789

  19. 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.

  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. 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

  2. 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

  3. [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

  4. Mono, bi- and trinuclear metal complexes derived from new benzene-1,4-bis(3-pyridin-2-ylurea) ligand. Spectral, magnetic, thermal and 3D molecular modeling studies

    NASA Astrophysics Data System (ADS)

    El-ghamry, Mosad A.; Saleh, Akila A.; Khalil, Saied M. E.; Mohammed, Amira A.

    2013-06-01

    New bis (pyridylurea) ligand, H2L, was synthesized by the reaction of ethylpyridine-2-carbamate (EPC) and p-phenylenediamine. The ligand was characterized by elemental analysis, IR, 1H NMR, electronic and mass spectra. Reaction of the prepared ligand with Co2+, Ni2+, Cu2+, Fe3+, VO2+ and UO22+ ions afforded mono, bi- and trinuclear metal complexes. Also, new mixed ligand complexes of the ligand H2L and 8-hydroxyquinoline (8-HQ) with Co2+, Ni2+, Cu2+ and Fe3+ ions were synthesized. The ligand behaves as bi- and tetradentate toward the transition metal ions, coordination via the pyridine sbnd N, the carbonyl sbnd O and/or the amidic sbnd N atoms in a non, mono- and bis-deprotonated form. The complexes were characterized by elemental and thermal analyses, IR, electronic and mass spectra as well as conductance and magnetic susceptibility measurements. The results showed that the metal complexes exhibited different geometrical arrangements such as square planar, tetrahedral, octahedral and square pyramidal arrangements. The Coats-Redfern equation was used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition steps of some complexes. 3D molecular modeling of the ligand, H2L and a representative complex were studied.

  5. Low-voltage top-emitting organic light-emitting devices with an organic double-heterojunction structure

    NASA Astrophysics Data System (ADS)

    Xie, Wenfa; Wu, Zhijun; Hu, Wei; Zhao, Yi; Li, Chuannan; Liu, Shiyong

    2005-05-01

    We demonstrate low-voltage top-emitting organic light-emitting devices with a narrow recombination zone confined by an organic double-heterojunction structure. The devices had a configuration of Al/Glass/ITO/m-MTDATA/NPB/Alq3/TPBI/Alq3/LiF/Al/Ag. In these devices, 4,4',4''-tris(3-methylphenylphenylamino)-triphenylamine (m-MTDATA), N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biph-enyl-4,4'-diamine (NPB), 2,2',2''-(1,3,5-phenylene)tris(1-phenyl-1H-benzimidazole) (TPBI) and tris (8-hydroxyquinoline) aluminium (Alq3) were used as the hole injection, hole transporting, hole blocking and emission/electron-transporting layers, respectively. They exhibit low driving voltages, for instance, ~200 cd m-2 at the voltage of 4 V. The maximum efficiency and luminance of the device are 1.628 cd A-1 and 9573 cd m-2.

  6. Nondoped-type red organic electroluminescent devices based on a 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran ultrathin layer

    NASA Astrophysics Data System (ADS)

    Xie, Wenfa; Liu, Shiyong

    2006-03-01

    Nondoped-type red organic electroluminescent devices based on a 4-(dicyanomethylene) -2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) ultrathin layer have been fabricated. When the ultrathin DCJTB layer is inserted between N, N'-bis-(1-naphthyl)-N, N'-diphenyl-1,1'-biph-enyl-4,4'-diamine (NPB) and tri-(8-hydroxyquinoline) aluminium (Alq3) (type A device), the emission from Alq3 is mixed with the emission from DCJTB and the colour purity of the device becomes poor. When utilizing the Alq3 (5 nm)/TPBI (45 nm) (TPBI: 2,2',2''-(1,3,5-phenylene)tris (1-phenyl-1 H-benzimidazole)) bilayer as a hole/exciton blocking and electron transporting layer (type B device), the emission from Alq3 disappears. We attribute it to the excitons confinement effect by the Alq3 (5 nm)/TPBI (45 nm) bilayer. The type B device with 0.2 nm DCJTB has a maximum efficiency of 2.20 cd A-1 and a luminance of 280 cd m-2 is achieved at 20 mA cm-2 with an EL efficiency of 1.41 cd A-1, and the CIE coordinates are (0.628, 0.369).

  7. LETTER TO THE EDITOR: High colour rendering index non-doped-type white organic light-emitting devices with a RGB-stacked multilayer structure

    NASA Astrophysics Data System (ADS)

    Xie, Wenfa; Zhao, Yi; Li, Chuannan; Liu, Shiyong

    2005-12-01

    A non-doped-type white organic light-emitting device with high colour rendering index has been reported. The structure of the device is ITO/NPB (50 nm)/TPBI (3 nm)/Alq3 (d nm)/DCM2 (0.1 nm)/TPBI (40 - d nm)/Alq3 (10 nm)/LiF/Al, where NPB is N, N'-bis-(1-naphthyl)-N, N'-diphenyl-1, 1'-biph-enyl-4, 4'-diamine, TPBI is 2, 2', 2''-(1, 3, 5-phenylene) tris(1-phenyl-1H-benzimidazole), Alq3 is tris (8-hydroxyquinoline) aluminium, DCM2 is [2-methyl-6-[2-(2, 3, 6, 7-tetrahydro-1H, 5H-benzo[ij] quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene] propane-dinitrile. Through the optimization of d, pure white emission with CIE coordinates of (0.3198, 0.3400) at 9 V was obtained, at which the colour temperature and colour rendering index were 6080 K and 97, respectively. The CIE coordinates of the device change from (0.4552, 0.3867) at 4 V to (0.2864, 0.2865) at 19 V that are well in the white region. Its maximum luminance was 10 855 cd m-2 at 19 V and maximum power efficiency was 1.31 lm W-1 at 5 V.

  8. A novel dichromate-sensitive fluorescent nano-chemosensor using new functionalized SBA-15.

    PubMed

    Hosseini, Morteza; Gupta, Vinod Kumar; Ganjali, Mohammad Reza; Rafiei-Sarmazdeh, Zahra; Faridbod, Farnoush; Goldooz, Hassan; Badiei, Ali Reza; Norouzi, Parviz

    2012-02-17

    A novel fluorescence nano-chemosensor for Cr(2)O(7)(2-) anion has been developed by assembly of fluorescent aluminum complex of 8-hydroxyquinoline (AlQ(x)) within the channels of modified SBA-15. SBA-SPS-AlQ(x) shows a fluorescence emission at 486 nm. The observed remarkable fluorescence of SBA-SPS-AlQ(x) quenches in presence of Cr(2)O(7)(2-) anion. The results showed that this fluorescent nano-material can be a useful chemo-sensor for determination of dichromate anions in aqueous solutions. The linear detecting range of fluorescent nano-chemosensor for Cr(2)O(7)(2-) anion was 0.16-2.9 μmol L(-1). The lowest limit of detection (LDL) was also found to be 0.2 ng mL(-1) in aqueous solutions. SBA-SPS-AlQ(x) showed selectively and sensitively fluorescent quenching response toward Cr(2)O(7)(2-) ion in comparison with I(3)(-), NO(3)(-), CN(-), CO(3)(2-), Br(-), Cl(-), F(-), H(2)PO(4)(-) and SO(4)(2-) ions, which was because of the higher stability of its inorganic complex with dichromate ion. PMID:22244170

  9. 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.

  10. 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.

  11. Red organic light emitting device based on TPP and a new host material

    NASA Astrophysics Data System (ADS)

    Janghouri, Mohammad; Mohajerani, Ezeddin; Amini, Mostafa M.; Najafi, Ezzatollah

    2014-02-01

    A novel coating method for fabrication of red OLEDs by using a new host material has been developed with the aid of a single furnace. The host material, zinc complex, was prepared from the reaction of zinc acetate and 2-methyl-8-hydroxyquinoline and after characterization by UV-vis, FT-IR, and 1H NMR spectroscopes was used as an emitting material in the fabrication of OLEDs. Since meso-tetraphenylporphyrin (TPP) and zinc complex have a close molecular weight, both materials were evaporated from a single furnace. Devices with TPP and structures of ITO/PEDOT:PSS (55 nm)/PVK (90 nm)/zinc complex:TPP (65 nm)/Al (180 nm) were fabricated; Without TPP green and with TPP red emission was achieved. The device with 2 % TPP that doped into the zinc complex showed the purest red emission among all devices. The device showed the CIE coordinates of 0.70 and 0.28 at 14 V and a maximum luminance of about 94.2 cd/m2. This new method is a promising candidate for fabrication of low cost red OLEDs with a more homogeneous layer.

  12. 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

  13. 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.

  14. A Cell-Permeable Ester Derivative of the JmjC Histone Demethylase Inhibitor IOX1

    PubMed Central

    Schiller, Rachel; Scozzafava, Giuseppe; Tumber, Anthony; Wickens, James R; Bush, Jacob T; Rai, Ganesha; Lejeune, Clarisse; Choi, Hwanho; Yeh, Tzu-Lan; Chan, Mun Chiang; Mott, Bryan T; McCullagh, James S O; Maloney, David J; Schofield, Christopher J; Kawamura, Akane

    2014-01-01

    The 2-oxoglutarate (2OG)-dependent Jumonji C domain (JmjC) family is the largest family of histone lysine demethylases. There is interest in developing small-molecule probes that modulate JmjC activity to investigate their biological roles. 5-Carboxy-8-hydroxyquinoline (IOX1) is the most potent broad-spectrum inhibitor of 2OG oxygenases, including the JmjC demethylases, reported to date; however, it suffers from low cell permeability. Here, we describe structure–activity relationship studies leading to the discovery of an n-octyl ester form of IOX1 with improved cellular potency (EC50 value of 100 to 4 μm). These findings are supported by in vitro inhibition and selectivity studies, docking studies, activity versus toxicity analysis in cell cultures, and intracellular uptake measurements. The n-octyl ester was found to have improved cell permeability; it was found to inhibit some JmjC demethylases in its intact ester form and to be more selective than IOX1. The n-octyl ester of IOX1 should find utility as a starting point for the development of JmjC inhibitors and as a use as a cell-permeable tool compound for studies investigating the roles of 2OG oxygenases in epigenetic regulation. PMID:24504543

  15. 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

  16. Effect of desiccant on the performance of green organic light-emitting device

    NASA Astrophysics Data System (ADS)

    Zhong, Jian; Gao, Zhuo; Yu, Junsheng; Jiang, Yadong

    2011-01-01

    A green organic light-emitting diodes (OLED) with a multilayer structure of indium-tin oxide (ITO)/copper-phthalocyanine (CuPc) (200Å)/ N,N'-bis(1-naphthyl)- N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α-NPD) (600Å)/ N'- diphenyl- N,N'-tris(8-hydroxyquinoline) aluminium (Alq3) (400Å):10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7- tetrahydro-1 H,5 H,11 H-( l)benzopyropyrano(6,7,8-i, j)quinolizin-11-one (C545T) (2%)/Alq3 (200Å)/LiF (10Å)/Al (1000Å) was prepared via vacuum thermal evaporation. To reduce the impact of water vapor and oxygen on the device, we encapsulated it with a kind of specific and efficient desiccant, called DESIPASTE, under the protection of high-purity nitrogen. By analyzing a series of optical characteristics of OLEDs, the results showed that this desiccant can improve the brightness about 500 and 250 cd/m2 at same driving voltage and current density, respectively. The electroluminescent (EL) spectra were hardly affected except a very weak blue shift of broadband emission peak. It turns out that encapsulation with DESIPASTE is a simple and efficient way to improve the performance of OLED.

  17. Operating longevity of organic light-emitting diodes with perylene derivatives as aggregating light-emitting-layer additives: Expansion of the emission zone

    NASA Astrophysics Data System (ADS)

    Jarikov, Viktor V.; Young, Ralph H.; Vargas, J. Ramon; Brown, Christopher T.; Klubek, Kevin P.; Liao, Liang-Sheng

    2006-11-01

    We describe aggregating perylene derivatives as light-emitting-layer (LEL) additives in organic light-emitting diodes (OLEDs). These molecules readily form emissive aggregates when added to the LEL. In the resulting devices, the aggregates show moderate external quantum efficiencies of 0.9%-1.7%, which can be improved to 2.7%-4.0% by further adding a proper dopant. Importantly, addition of these polycyclic aromatic hydrocarbons increases the half-life (t50) of undoped and doped OLEDs by 30-150 times. Thus, 11cd/A green and 5.2cd/A red devices are produced that have pure color, Commission Internationale de l'Eclairage 1931 2° color chromaticity coordinates (CIEx ,y) 0.32, 0.63 and 0.64, 0.36, respectively, and t50 of 30 000 and 200 000h, respectively, upon operation at 40mA/cm2. A possible link between the thickness of the emission zone and the lifetime increase is illustrated by comparing aluminum 8-hydroxyquinoline chelate (Alq3) as an LEL host versus an Alq3+dibenzo[b ,k]perylene mixed host using C545T as an emissive probe. The comparison suggests that the emission zone and probably the electron-hole recombination zone are expanded for the mixed host.

  18. Diffusivity and mobility of non-equilibrium carriers in organic semiconductors: Existence of critical field determining temperature dependence

    NASA Astrophysics Data System (ADS)

    Tripathi, Durgesh C.; Sinha, Dhirendra K.; Mohapatra, Y. N.

    2013-10-01

    The role of disorder in controlling diffusivity and mobility of charge-carriers in the hopping regime of transport within a potential landscape has become especially significant for organic semiconductors. The temperature and field dependence of diffusivity (D) and mobility (μ) of injected charge-carriers have been simultaneously measured using electroluminescence transients for representative organic thin-films of tris(8-hydroxyquinoline) aluminum (III) (Alq3) and poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO). Significantly, the field dependence of diffusivity at different temperatures is similar except for a shift of a critical field beyond which it shows a sharp increase. The critical field is shown to be linearly decreasing with temperature ultimately vanishing at a characteristic limit T∗, and the slope is a measure of the localization length. The normalization of diffusivity is used to demonstrate the role of field in controlling temperature dependence. The scheme has been used to neatly decouple contributions from energetic (diagonal) and positional (off-diagonal) disorder thus enabling independent experimental determination of all the parameters of standard and correlated versions of Gaussian disorder model. The results demonstrate the validity of Gaussian disorder model even for non-equilibrium carriers, and that the parameters can be obtained with appropriate scaling of the field in such cases.

  19. 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. PMID:19615516

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

    PubMed

    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. PMID:27221767

  1. 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. PMID:25535798

  2. Photonic nanosensor for colorimetric detection of metal ions.

    PubMed

    Yetisen, Ali K; Montelongo, Yunuen; Qasim, Malik M; Butt, Haider; Wilkinson, Timothy D; Monteiro, Michael J; Yun, Seok Hyun

    2015-01-01

    The real-time sensing of metal ions at point of care requires integrated sensors with low energy and sample consumption, reversibility, and rapid recovery. Here, we report a photonic nanosensor that reversibly and quantitatively reports on variation in the concentrations of Pb(2+) and Cu(2+) ions in aqueous solutions (<500 μL) in the visible region of the spectrum (λ(max) ≈ 400-700 nm). A single 6 ns laser pulse (λ = 532 nm) was used to pattern an ∼10 μm thick photosensitive recording medium. This formed periodic AgBr nanocrystal (ø ∼ 5-20 nm) concentrated regions, which produced Bragg diffraction upon illumination with a white light source. The sensor functionalized with 8-hydroxyquinoline allowed sensing through inducing Donnan osmotic pressure and tuning its lattice spacing. The sensor quantitatively measured Pb(2+) and Cu(2+) ion concentrations within the dynamic range of 0.1-10.0 mM with limits of detection of 11.4 and 18.6 μM in under 10 min. The sensor could be reset in 3 min and was reused at least 100 times without compromising its accuracy. The plasmonic nanosensor represents a simple and label-free analytical platform with potential scalability for applications in medical diagnostics and environmental monitoring. PMID:25710792

  3. Organic semiconductor lasers as integrated light sources for optical sensor systems

    NASA Astrophysics Data System (ADS)

    Punke, Martin; Woggon, Thomas; Stroisch, Marc; Ebenhoch, Bernd; Geyer, Ulf; Karnutsch, Christian; Gerken, Martina; Lemmer, Uli; Bruendel, Mathias; Wang, Jing; Weimann, Thomas

    2007-09-01

    We demonstrate the feasibility of organic semiconductor lasers as light sources for lab-on-a-chip systems. These lasers are based on a 1D- or 2D-photonic crystal resonator structure providing optical feedback in the active laser material that is deposited on top, e.g. aluminum tris(8-hydroxyquinoline) (Alq 3) doped with the laser dye 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM). We investigated different fabrication methods for the resonator structures, like thermal nanoimprint, UV nanoimprint, and laser interference lithography. Different substrate materials commonly used in lab-on-a-chip systems, e.g. PMMA, Topas, and Ormocer were deployed. By changing the distributed feedback grating periodicity, we demonstrate a tuning range for a single material system of more than 120 nm. The investigated organic semiconductor lasers are optically pumped. External optical pumping provides a feasible way for one-time-use chips. Our recent success of pumping organic lasers with a low-cost laser diode also renders hand-held systems possible. As a further step towards the integration of organic lasers in sensor systems, we demonstrate the coupling of an organic laser into polymeric waveguides which can be combined with microfluidic channels. The integrated organic lasers and the waveguides are both fabricated on the same polished PMMA substrate using thermal nanoimprint lithography and deep-UV modification, respectively. We could demonstrate the guiding of the laser light in single-mode waveguides.

  4. Determination of minor elements in water by emission spectroscopy

    USGS Publications Warehouse

    Barnett, Paul R.; Mallory, E.C.

    1971-01-01

    With the emission spectrograph, the analyst is able to determine many minor elements simultaneously in water samples. Spectrographic methods differ chiefly in techniques of preconcentrating the elements. For waters with dissolved solids of less than 1,000 milligrams per liter, the method of evaporating to dryness and determining the elements in the dried residue is sensitive, precise, and reasonably accurate. The lower limits of detection vary with the quantity of dissolved solids. Twenty-four elements are determined by this method. For waters with more than 1,000 milligrams per liter of dissolved solids, it is necessary to separate the minor elements from the major constituents before spectrographically determining the former, in order to achieve adequate lower limits of detection. Such procedures generally require more time than the residue method. In the first of two such procedures given, 21 of the metallic elements are precipitated with thioacetamide prior to spectrographic determination. In an alternate procedure, 18 elements are precipitated quantitatively with complexing reagents 8-hydroxyquinoline, tannic acid, and thioanlide. This method is faster than the thioacetamide method, but at the sacrifice of some elements. A Fortran IV computer program for processing densitometric data is given in the section 'Computer Program.'

  5. Anion-directed self-assembly of two half-sandwich ruthenium-based metallamacrocycles as catalysts for water oxidation.

    PubMed

    Yu, Wei-Bin; He, Qing-Ya; Shi, Hua-Tian; Yuan, Guozan; Wei, Xianwen

    2015-01-01

    The binuclear [η(6) -(cymene)Ru(L)]2 (OTf)2 (TfO(-) =trifluoromethanesulfonate) and tetranuclear [η(6) -(cymene)Ru(L)]4 (NO3 )4 metallacycles were prepared by treating the pyridyl-substituted 8-hydroxyquinoline ligand (E)-2-[2-(pyridin-3-yl)vinyl]quinolin-8-ol (HL) with [(p-cymene)Ru(μ-Cl)Cl]2 in the presence of AgOTf or AgNO3 . The molecular structures of these complexes were confirmed by single-crystal X-ray diffraction, which revealed that both complexes have macrocycle frameworks induced by the TfO(-) and NO3 (-) counteranions, respectively. The electrochemical properties of the two metallacycles were investigated by cyclic voltammetry, which showed that they have great potential as catalysts for water oxidation. Good efficiency was obtained by utilizing the nitrate complex as a water oxidation catalyst in the presence of a Ce(IV) salt as an oxidant at high pH values. PMID:25303729

  6. 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. PMID:23142057

  7. 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.

  8. Processing of functional polymers and organic thin films by the matrix-assisted pulsed laser evaporation (MAPLE) technique

    NASA Astrophysics Data System (ADS)

    Piqué, A.; Wu, P.; Ringeisen, B. R.; Bubb, D. M.; Melinger, J. S.; McGill, R. A.; Chrisey, D. B.

    2002-01-01

    The matrix-assisted pulsed laser evaporation (MAPLE) technique has been successfully used to deposit highly uniform thin films of various functional materials such as non-linear optical (NLO) organic materials, conductive polymers, luminescent organic molecules and several types of proteinaceous compounds. MAPLE is a laser evaporation technique for growing thin films of organic and polymeric materials which involves directing a pulsed laser beam (λ=193 nm; fluence=0.01-0.5 J cm -2) onto a frozen target (-40 to -160 °C) consisting of a solute polymeric or organic compound dissolved in a solvent matrix. Using MAPLE, thin films of N-(4-nitrophenyl)-( L)-prolinol or NPP, an NLO material; polypyrrole, a conductive polymer; and tris-(8-hydroxyquinoline) aluminum or Alq3, a luminescent organic compound, have been separately deposited with minor (in the case of Alq3) or no degradation (for the NPP and polypyrrole) to their optical and electrical properties. The MAPLE process has also been used to deposit discrete thin film micro-arrays of biotinylated bovine serum albumin (BSA). The deposited BSA films, after washing with a blocking protein and fluorescently tagged streptavidin, fluoresce when exposed to UV. This fluorescence indicates that the biochemical specificity of the transferred biotinylated protein is unaffected by the MAPLE process. These results demonstrate that the MAPLE technique can be used for growing thin films of functional polymer and active biomaterials.

  9. 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.

  10. Electron and spin transport studies of gated lateral organic devices

    NASA Astrophysics Data System (ADS)

    Alborghetti, S.; Coey, J. M. D.; Stamenov, P.

    2012-12-01

    In view of the many, often contradictory, reports of magneto-resistance (MR) in spin valve stacks containing a layer of organic semiconductor, mostly of the small molecule variety, we have investigated interdigitated lateral structures with an organic layer deposited in the narrow gap between two ferromagnetic electrodes, which are well-suited for studying charge and spin transport in novel (high resistivity) semiconducting materials. For the channel material we used three different organic semiconductors, the small molecule tris-(8-hydroxyquinoline) aluminum (Alq3), single crystals of pentacene, and the conductive polymer poly(3-hexylthiophene) (P3HT). The channel length was 80 nm. Temperature-dependent current-voltage characteristics reveal that in all instances the current is limited by field-assisted thermionic injection over an energy barrier at the metal/organic interface. No measurable magneto-resistance was observed down to 7 K. The interface energy barrier, together with the vastly different electronic structure of metals and organics close to the Fermi level, preclude spin injection. Nonetheless, unlike the case of inorganic semiconductors, the insertion of an artificial tunnel barrier at the contact did not improve spin injection. Gate-dependent measurements exhibited short-channel effects and transistor operation with on/off ratios of 103, but no magneto-resistance. We suggest the observations are a consequence of the formation of bipolaron-states at increasing carrier concentration.

  11. 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

    2016-01-01

    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 180(°). PMID:26846891

  12. 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.

  13. Coordination properties of a metal chelator clioquinol to Zn(2+) studied by static DFT and ab initio molecular dynamics.

    PubMed

    Rodríguez-Santiago, Luis; Alí-Torres, Jorge; Vidossich, Pietro; Sodupe, Mariona

    2015-05-28

    Several lines of evidence supporting the role of metal ions in amyloid aggregation, one of the hallmarks of Alzheimer's disease (AD), have turned metal ion chelation into a promising therapeutic treatment. The design of efficient chelating ligands requires proper knowledge of the electronic and molecular structure of the complexes formed, including their hydration properties. Among various potential chelators, clioquinol (5-chloro-7-iodo-8-hydroxyquinoline, CQH) has been evaluated with relative success in in vitro experiments and even in phase 2 clinical trials. Clioquinol interacts with Zn(ii) to lead to a binary metal/ligand 1 : 2 stoichiometric complex in which the phenolic group of CQH is deprotonated, resulting in Zn(CQ)2 neutral complexes, to which additional water molecules may coordinate. In the present work, the coordinative properties of clioquinol in aqueous solution have been analyzed by means of static, minimal cluster based DFT calculations and explicit solvent ab initio molecular dynamics simulations. Results from static calculations accounting for solvent effects by means of polarized continuum models suggest that the preferred metal coordination environment is tetrahedral Zn(CQ)2, whereas ab initio molecular dynamics simulations point to quasi degenerate penta Zn(CQ)2(H2O) and hexa Zn(CQ)2(H2O)2 coordinated complexes. The possible reasons for these discrepant results are discussed. PMID:25939963

  14. Cathode Formed by Thermal Evaporation of Ba:Al Alloy and Estimations of Barrier Height in an Organic LED

    NASA Astrophysics Data System (ADS)

    Ding, Lei; Zhang, Fang-Hui

    2011-06-01

    It is demonstrated that barium and aluminum alloy synthesized by melting in a glass tube under low vacuum is applicable for organic laser emitting diodes (LEDs) as a thin film cathode. The alloy film obtained by the thermal evaporation of pre-synthesized alloy is used in a single-boat organic LED device with the structure: indium tin oxide (ITO)/4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl(NPB)/tris-(8-hydroxyquinoline) aluminum(Alq3)/barium:aluminum alloy. The experimental results show that devices with this alloy film cathode exhibit better current density-voltage-luminance characteristics than those with a conventional pure Al cathode, and more weight of barium in aluminum leads to better performance of the devices. Characteristics of current density versus voltage for the electron-only devices are fitted by the Richardson—Schottky emission model, indicating that the electron injection barrier has a decrease of about 0.3 eV by this alloy cathode.

  15. 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

  16. 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.

  17. 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

  18. Encapsulating MAl 2O 4:Eu 2+, Dy 3+ (M = Sr, Ca, Ba) phosphors with triethanolamine to enhance water resistance

    NASA Astrophysics Data System (ADS)

    Ji, Ping Ting; Chen, Xiang Ying; Wu, Ye Qin

    2011-12-01

    Traditional aluminates phosphors with persistent luminescence are chemically unstable to water or moisture. Thus, how to improve the water-resistance of these phosphors is becoming a key issue in their practical applications. In this work, a series of alkaline earth aluminate phosphors including MAl 2O 4:Eu 2+, Dy 3+ (M = Sr, Ca, Ba) have been prepared by a co-precipitation synthesis and postannealing approach, using 8-hydroxyquinoline and sodium oxalate as precipitants. The samples before and after encapsulation were well characterized by means of XRPD, FESEM, FT-IR, TGA-DTG and PL techniques as well as water resistance measurements. The precipitants involved can react with Al 3+ and Sr 2+ (or Ca 2+, Ba 2+) to form complex compounds in aqueous solution, which further convert into porous phosphors by postannealing method under reducing atmosphere. Next, triethanolamine encapsulation at room temperature was conducted onto their surfaces to improve the water resistance. The results reveal that the encapsulation of aluminate phosphors with triethanolamine can effectively enhance the water resistance, and minimally affect on persistent phosphorescence.

  19. Multi-objective optimization of microcavity OLEDs with DBR mirror

    NASA Astrophysics Data System (ADS)

    Lu, Albert W.; Chan, J.; Ng, Alan Man Ching; Djurišić, A. B.; Rakić, A. D.

    2007-02-01

    In this work, the emission efficiency and spectral shift with respect to viewing angle were optimized by optimizing the design of the multi-layer top mirror of a microcavity OLED device. We first established criteria for the emission side mirror in order to optimize light intensity and spectral shift with viewing angle. Then we designed mirror using metallic and dielectric layers based on the target defined. The electroluminescence emission spectra of a microcavity OLED consisting of widely used organic materials, N,N'-di(naphthalene-1-yl)-N,N'-diphenylbenzidine (NPB) as a hole transport layer and tris (8-hydroxyquinoline) (Alq 3) as emitting and electron transporting layer was then calculated. Silver was used as the anode and back reflection mirror for the microcavity OLED. The simulation was performed for both the conventional LiF/Al cathode/top mirror and the optimized 5-layered top mirror. Our results indicate that by following the design procedure outlined, we simultaneously optimize the device for better light intensity and spectral shift with viewing angle.

  20. [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

  1. 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.

  2. 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.

  3. White electrophosphorescent devices based on tricolour emissive layers

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Hua, Yulin; Wu, Xiaoming; Zhang, Guohui; Hui, Juanli; Zhang, Lijuan; Liu, Qian; Ma, Liang; Yin, Shougen; Petty, M. C.

    2008-01-01

    We demonstrate high efficiency, white organic light-emitting devices based on a structure using multiple emissive layers and fabricated without a hole-injecting layer. 2,5,8,11-tetra-tertbutylperylene (TBPe) was used as the blue fluorescent layer and the overall device configuration was indium tin oxide (ITO)/N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB)/4,4'-N, N'-dicarbazole-biphenyl (CBP): bis[1-(phenyl)isoquinoline] iridium (III) acetylanetonate [Ir(piq)2(acac)]/CBP:fac-tris(2-phenylpyridine) iridium [Ir(ppy)3]/CBP: TBPe/2, 9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/(8-hydroxyquinoline) aluminium (Alq3)/LiF/Al. This structure possessed a maximum luminous efficiency of 14.2 cd A-1 at a current density of 4 mA cm-2 and a maximum brightness of 40 520 cd m-2 at 25 V. The Commission Internationale de L'Eclairage coordinates changed only from (0.27, 0.38) to (0.33, 0.38), with the brightness varying from 100 to 25 640 cd m-2, as the applied voltage was increased from 10 to 23 V.

  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. Segmented sediment probe for diffusive gradient in thin films technique.

    PubMed

    Docekal, Bohumil; Gregusova, Michaela

    2012-01-21

    A new modification of a constrained sediment probe was tested for application in the diffusive gradient in thin films technique (DGT). The sediment probes packed with agarose based resin and diffusive gels were exposed under laboratory conditions to well-mixed test solutions of cadmium and nickel as model elements. The reproducibility of metal uptake in segments (strips) of resin gel with anchored 8-hydroxyquinoline functional groups (Spheron-Oxin® ion exchanger) was studied. The relative yield of uptake of metals in resin gel strips, determined as the ratio of the time-averaged DGT-measured metal concentration and the concentration of a metal in the test solution, showed that the effective sampling area was larger than the geometric area of the resin gel strip. This relative yield is in very good agreement with the theoretical value obtained by the Finite Element Method (FEM) in calculation of diffusion processes. The performance of the modified constrained probe is demonstrated by an example of uranium, iron and manganese depth profiling in a spiked sediment core. Utilization of the new segmented sediment probe in the DGT technique is very simple. Its application does not require special devices and labor-intensive procedures. It can provide sediment depth profiles of metals with the resolution down to the millimetre level. PMID:22116834

  6. 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

  7. 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).

  8. Ligand substitution reactions of a phenolic quinolyl hydrazone; oxidovanadium (IV) complexes

    PubMed Central

    2011-01-01

    Background Quinoline ring has therapeutic and biological activities. Quinolyl hydrazones constitute a class of excellent chelating agents. Recently, the physiological and biological activities of quinolyl hydrazones arise from their tendency to form metal chelates with transition metal ions. In this context, we have aimed to study the competency effect of a phenolic quinolyl hydrazone (H2L; primary ligand) with some auxiliary ligands (Tmen, Phen or Oxine; secondary ligands) towards oxidovanadium (IV) ions. Results Mono- and binuclear oxidovanadium (IV) - complexes were obtained from the reaction of a phenolic quinolyl hydrazone with oxidovanadium (IV)- ion in absence and presence of N,N,N',N'- tetramethylethylenediamine (Tmen), 1,10-phenanthroline (Phen) or 8-hydroxyquinoline (Oxine). The phenolic quinolyl hydrazone ligand behaves as monobasic bidentate (NO- donor with O- bridging). All the obtained complexes have the preferable octahedral geometry except the oxinato complex (2) which has a square pyramid geometry with no axial interaction; the only homoleptic complex in this study. Conclusion The ligand exchange (substitution/replacement) reactions reflect the strong competency power of the auxiliary aromatic ligands (Phen/Oxine) compared to the phenolic quinolyl hydrazone (H2L) towards oxidovanadium (IV) ion; (complexes 2 and 3). By contrast, in case of the more flexible aliphatic competitor (Tmen), an adduct was obtained (4). The obtained complexes reflect the strength of the ligand field towards the oxidovanadium (IV)- ion; Oxine or Phen >> phenolic hydrazone (H2L) > Tmen. PMID:21846387

  9. 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)

  10. 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

  11. 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.

  12. Behavior of charge carriers and excitons in multilayer organic light-emitting diodes made from a polysilane polymer as monitored with electroluminescence

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroyuki; Hoshino, Satoshi

    1996-01-01

    Using electroluminescence (EL) as a monitor, we have investigated the behavior of charge carriers injected from electrodes and excitons generated by the recombination of charge carriers in multilayer organic light-emitting diodes (LEDs) using poly(methylphenylsilane) (PMPS) as a hole transporting material. Our multilayer LEDs have two or three functional organic layers including Coumarin 6 [3-(2'-benzothiazolyl)-7-diethylaminocoumarin, abbreviated as C6] and/or tris-(8-hydroxyquinoline) aluminum layers as well as a PMPS layer. When the LEDs were fabricated, two parameters of the C6 layer were changed, the layer thickness (30-120 nm) and the dye concentration (1-100 wt %). We employed a combined analysis of the dependence of the EL spectra on the thickness and dye concentration of the C6 layer, the dye-selective fluorescence spectra and the current-voltage-EL characteristics, to reveal the thickness of the electron-hole capture zone and the behavior of charge carriers and excitons during operation in these LEDs.

  13. Effects of doping dyes on the electroluminescent characteristics of multilayer organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroyuki; Hoshino, Satoshi

    1996-06-01

    We report the effects of dyes doped in the emitting layer on the electroluminescent characteristics of multilayer organic light-emitting diodes (LEDs) using a polysilane polymer, poly(methylphenylsilane) (PMPS), as the hole transporting material. We formed the emitting layer by dispersing in poly(styrene) (PS), one of four dyes whose fluorescence ranged from blue to orange. Two- or three-layer LEDs were prepared by combining PMPS and dye doped PS layers with the indium tin oxide and aluminum used for the hole and electron injecting electrodes, respectively. The three-layer LEDs had an additional vacuum-deposited tris-(8-hydroxyquinoline) aluminum layer. The electroluminescent (EL) characteristics of these multilayer organic LEDs, such as the current-voltage-EL intensity curve, the relative EL efficiency, and the EL emitting species, exhibit a marked dependence on the emitting dye. The observed dependence can be described consistently in terms of the dependence of the charge carrier trapping efficiency on the emitting dyes.

  14. Light Emitting Heterojunctions Based on Fully Conjugated Heterocyclic Aromatic Rigid-rod Polymer PBT

    NASA Astrophysics Data System (ADS)

    Bai, S. J.; Wu, C. C.; Cheng, H. Y.; Wang, W.

    2003-03-01

    Poly(p-phenylenebenzobisthiazole), PBT, is a heterocyclic aromatic rigid-rod polymer having a fully conjugated backbone, excellent stabilities and opto-electronic properties. We investigated multi-layer heterojunctions of PBT and low molar compounds of 3-(2-benzothiazoly)-7-(diethylamino), C6, and tris-(8-hydroxyquinoline) aluminum, Alq3, using PBT as a hole injecting and transporting material. A PBT polymer with an intrinsic viscosity of 18.0 dL/g was dissolved in Lewis acid and spin-coated onto an indium-tin-oxide (ITO) substrate. The acid was removed via coagulation. The low molar compounds were evaporated onto the ITO substrate or the thin PBT film on the ITO substrate. UV-Vis absorption spectra over 200 to 800 nm revealed different band gaps for PBT, C6 and Alq3. Scanning electron microscopy determined that the resultant PBT and low molar compound layer thicknesses were about 23 nm and 50 nm, respectively. Aluminum was evaporated onto the multilayer heterojunction as an electron injector for electroluminescence response leading to a lower I-V threshold voltage and a higher emission brightness. This was mainly because of significant balance in the numbers of the hole and the electron injected and transported in the heterojunctions.

  15. Identification of Xylem Occlusions Occurring in Cut Clematis (Clematis L., fam. Ranunculaceae Juss.) Stems during Their Vase Life

    PubMed Central

    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. PMID:22919351

  16. [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

  17. 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

  18. 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.

  19. 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.

  20. 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. PMID:24815561

  1. 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.

  2. Characterization of the second prosthetic group of the flavoenzyme NADH-acceptor reductase (component C) of the methane mono-oxygenase from Methylococcus capsulatus (Bath).

    PubMed Central

    Colby, J; Dalton, H

    1979-01-01

    1. A new two-step purification is described that routinely yields 100mg quantities of component C for biochemical studies. 2. Chemical analyses show component C purified by this procedure to contain 2 g-atoms of iron, 2 mol of acid-labile sulphide (S) and 1 mol of FAD per mol of protein. 3. The Fe-S core of component C was extruded by treating the protein with p-methoxybenzenethiol in hexamethyl phosphoramide/50mM-Tris/HCl buffer, pH 8.5 (4:1, v/v), under anaerobic conditions. The spectral properties of the extruded core suggest that component C contains 1 mol of [2Fe-2S(S-Cys)4] centre per mol of protein. 4. E.p.r. spectroscopy confirms the presence of a Fe-S centre in component C. 5. Component C catalyses the reduction by NADH of ferricyanide, 2,6-dichlorophenol-indophenol or horse heart cytochrome c, with specific activities of 50--230 units/mg of protein. 6. The optimum pH for the NADH-acceptor reductase activity is 8.5--9.0, and the apparent Km values for NADH and NADPH are 0.05mM and 15.5mM respectively. 7. Unlike methane mono-oxygenase activity, NADH-acceptor reductase activity of component C is not inhibited by 8-hydroxyquinoline or by acetylene. PMID:220953

  3. 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

  4. 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.

  5. Novel insight into antimicrobial resistance and sensitivity phenotypes associated to qac and norA genotypes in Staphylococcus aureus.

    PubMed

    Marchi, Emmanuela; Furi, Leonardo; Arioli, Stefania; Morrissey, Ian; Di Lorenzo, Valeria; Mora, Diego; Giovannetti, Luciana; Oggioni, Marco Rinaldo; Viti, Carlo

    2015-01-01

    Staphylococcus aureus strains harboring QacA, QacB, QacC, QacG transporters and norA promoter up-regulating mutations were characterized by phenotype microarray (PM), standard methods for susceptibility testing, and ethidium bromide efflux assays, in order to increase knowledge on phenotypes associated to efflux pumps and their substrates. PM data and standard susceptibility testing lead to the identification of new potential efflux targets, such as guanidine hydrochloride or 8-hydroxyquinoline for QacA and QacC pumps, respectively. The identification of compounds to which the presence of efflux pumps induced increased susceptibility opens new perspectives for potential adjunct anti-resistance treatment (i.e. strains bearing QacB transporters showed increased susceptibility to thioridazine, amitriptyline and orphenadrine). Although the tested isolates were characterized by high degree of heterogeneity, a hallmark of clinical isolates, direct ethidium bromide efflux assays were effective in highlighting differences in efflux efficiency among strains. These data add to characterization of substrate specificity in the different classes of staphylococcal multidrug efflux systems conferring specific substrate profiles and efflux features to each of them. PMID:25081379

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

    NASA Astrophysics Data System (ADS)

    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 1H, 13C and 93Nb 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 93Nb NMR spectra of 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. 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

  9. Synthesis, characterization and antibacterial studies on some mixed ligand thorium complexes with N- and O-donor ligands.

    PubMed

    Patil, Sunil S; Thakur, Ganesh A; Shaikh, Manzoor M

    2011-01-01

    Mixed ligand Th(IV) complexes of the type [M(Q)(L)(NO3)2] x 2H2O have been synthesized using 8-hydroxyquinoline (HQ) as a primary ligand and N- and/or O- donor amino acids (HL) such as L-threonine, L-tryptophan and L-isoleucine as secondary ligands. The metal complexes have been characterized on the basis of elemental analysis, electrical conductance, room temperature magnetic susceptibility measurements, spectral and thermal studies. The electrical conductance studies of the complexes in DMF in 10(-3). M concentration indicate their non-electrolytic nature. Room temperature magnetic susceptibility measurements revealed diamagnetic nature of the complexes. Electronic absorption spectra of the complexes show intra-ligand and charge transfer transitions, respectively. Bonding of the metal ion through N- and O-donor atoms of the ligands revealed by IR studies and the chemical environment of the protons is also confirmed by NMR studies. The thermal analysis data of the complexes indicate the presence of crystalline water molecules. The tube dilution method has been used to study the antibacterial activity of the complexes against the pathogenic bacteria S. aureus, C. diphtheriae, S. typhi and E. coli. PMID:22125953

  10. Mediation of donor–acceptor distance in an enzymatic methyl transfer reaction

    PubMed Central

    Zhang, Jianyu; Kulik, Heather J.; Martinez, Todd J.; Klinman, Judith P.

    2015-01-01

    Enzymatic methyl transfer, catalyzed by catechol-O-methyltransferase (COMT), is investigated using binding isotope effects (BIEs), time-resolved fluorescence lifetimes, Stokes shifts, and extended graphics processing unit (GPU)-based quantum mechanics/molecular mechanics (QM/MM) approaches. The WT enzyme is compared with mutants at Tyr68, a conserved residue that is located behind the reactive sulfur of cofactor. Small (>1) BIEs are observed for an S-adenosylmethionine (AdoMet)-binary and abortive ternary complex containing 8-hydroxyquinoline, and contrast with previously reported inverse (<1) kinetic isotope effects (KIEs). Extended GPU-based computational studies of a ternary complex containing catecholate show a clear trend in ground state structures, from noncanonical bond lengths for WT toward solution values with mutants. Structural and dynamical differences that are sensitive to Tyr68 have also been detected using time-resolved Stokes shift measurements and molecular dynamics. These experimental and computational results are discussed in the context of active site compaction that requires an ionization of substrate within the enzyme ternary complex. PMID:26080432

  11. 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

  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. 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

  14. 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

  15. Mechanism of ionophoric transport of indium-111 cations through a lipid bilayer membrane

    SciTech Connect

    Choi, H.O.; Hwang, K.J.

    1987-01-01

    The use of mobile ionophores to facilitate the transport of /sup 111/In through a lipid bilayer membrane has broad applications in liposome technology and cell labeling. However, the mechanism of such ionophore-mediated transport of /sup 111/In through a lipid bilayer membrane is not completely clear. The present report describes the correlations of the behaviors of ionophoric loading of /sup 111/In into liposomes with the lipophilicity and the indium-binding affinity of three ionophores, namely, 8-hydroxyquinoline, acetylacetone, and tropolone. Our results suggest that the mechanism of the ionophoric transport of /sup 111/In through a lipid bilayer membrane involves the rapid exchange of /sup 111/In cations among the ionophores in both the aqueous solution and the lipid bilayer. Furthermore, the effectiveness of an ionophore in facilitating the transport of /sup 111/In from the external aqueous compartment to the entrapped nitrilotriacetic acid depends not only on the lipophilicity of the (/sup 111/In)ionophore complex, but also on the lipophilicity of the free ionophore itself and the competition of /sup 111/In between nitrilotriacetic acid inside the inner aqueous compartment of the liposome and the ionophore imbedded in the lipid bilayer membrane of the liposome.

  16. Surprisingly bright near-infrared luminescence and short radiative lifetimes of ytterbium in hetero-binuclear Yb-Na chelates.

    PubMed

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

    2009-08-17

    New heterobinuclear lanthanide complexes with benzoxazole-substituted 8-hydroxyquinolines, [Ln(ligand)(2)(mu-ligand)(2)Na] (Ln: Yb, Lu), have been prepared and their structure established by X-ray crystallography, (1)H NMR spectroscopy, and photophysical studies. The complexes display efficient ligand-sensitized near-infrared luminescence of ytterbium at 925-1075 nm with lifetimes and quantum yields as high as 22 micros and 3.7%, in the solid state, and 20 micros and 2.6% in CH(2)Cl(2) solution, respectively. These quantum yields are the highest reported to date for ytterbium complexes with organic ligands containing C-H bonds. A long-wavelength and intense intraligand charge-transfer transition (lambda(max) = 446-456 nm; epsilon approximately 1.2 x 10(4) M(-1) cm(-1)) allows for the excitation of infrared luminescence with visible light up to 600 nm. Remarkable features of these complexes include (i) quantitative ligand-to-Yb(III) energy transfer resulting in high overall efficiency of the ytterbium luminescence, (ii) unusually short radiative lifetime of the Yb(III) ion, 706-745 micros for solutions in CH(2)Cl(2), calculated from the f-f absorption spectra, and 513-635 micros estimated for solid state samples from quantum yield and lifetime data, and (iii) the unexpected large influence of second-sphere composition on the radiative lifetime of ytterbium. PMID:19555059

  17. A highly selective fluorescent probe for pyrophosphate detection in aqueous solutions.

    PubMed

    Ganjali, M R; Hosseini, M; Aboufazeli, F; Faridbod, F; Goldooz, H; Badiei, A R

    2012-01-01

    A novel and simple fluorescence enhancement method is introduced for selective pyrophosphate (PPi) sensing in an aqueous solution. The method is based on a 1:1 metal complex formation between tris(8-hydroxyquinoline-5-sulphonate) thulium(III) [Tm(QS)(3)] and PPi ion. The linear response covers a concentration range of 1.6 × 10(-7) -1.0 × 10(-5)  mol/L PPi and the detection limit is 2.3 × 10(-8)  mol/L. The association constant of Tm(QS)(3) -PPi complex was calculated as 2.6 × 10(5)  mol/L. Tm(QS)(3) shows a selective and sensitive fluorescence enhancement toward PPi ion in comparison with I(3)(-), NO(3)(-), CN(-), CO(3)(2-), Br(-), Cl(-), F(-), H(2) PO(4) (-) and SO(4)(2-), which is attributed to higher stability of the inorganic complex between pyrophosphate ion and Tm(QS)(3). PMID:21735538

  18. 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.

  19. PET neuroimaging studies of [(18)F]CABS13 in a double transgenic mouse model of Alzheimer's disease and nonhuman primates.

    PubMed

    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

    2015-04-15

    Fluorine-18 labeled 2-fluoro-8-hydroxyquinoline ([(18)F]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 [(18)F]CABS13 was achieved by radiofluorination followed by deprotection of an O-benzyloxymethyl group. Automated production and formulation of [(18)F]CABS13 resulted in 19 ± 5% uncorrected radiochemical yield, relative to starting [(18)F]fluoride, with ≥95% chemical and radiochemical purities, and high specific activity (>2.5 Ci/μmol) within 80 min. Temporal PET neuroimaging studies were carried out in female transgenic B6C3-Tg(APPswe,PSEN 1dE9)85Dbo/J (APP/PS1) and age-matched wild-type (WT) B6C3F1/J control mice at 3, 7, and 10 months of age. [(18)F]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 nonhuman primates revealed that the tracer had low uptake in the brain and rapid formation of a hydrophilic radiometabolite. Identification of more metabolically stable (18)F-hydroxyquinolines that can be readily accessed by the radiochemical strategy presented herein is underway. PMID:25776827

  20. 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

  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. 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

  3. Structural diversity in binuclear complexes of alkaline earth metal ions with 4,6-diacetylresorcinol

    NASA Astrophysics Data System (ADS)

    Shebl, Magdy; Khalil, Saied M. E.; Taha, A.; Mahdi, M. A. N.

    2012-11-01

    A new series of binuclear and mixed-ligand complexes with the general formula: [M 2(LO)yClz]; where M = Mg(II), Ca(II), Sr(II) and Ba(II); H2L = 4,6-diacetylresorcinol, the secondary ligand L' = acetylacetone (acac), 8-hydroxyquinoline (8-HQ) or 2,2'-bipyridyl (Bipy), n = 0-2, m = 1, 2, x = 0, 1, 2, 4, y = 0, 2, 4, 5 and z = 0-2; have been synthesized. They have been characterized by the analytical and spectral methods (IR, 1H NMR and mass) as well as TGA and molar conductivity measurements. The spectroscopic and conductance data suggested that the H2L ligand behaves as a neutral, monobasic or dibasic tetradentate ligand, depending on the basicity of the secondary ligand, through the two phenolic and two carbonyl groups. Binuclear octahedral geometry has been assigned to all of the prepared complexes in various molar ratios 2:2; 2:2:2; 1:2:1 and 1:2:4 (L:M:L'). Molecular orbital calculations were performed for the ligands and their complexes using Hyperchem 7.52 program on the bases of PM3 level and the results were correlated with the experimental data. The ligand and some of its alkaline metal(II) complexes showed antibacterial activity towards some of Gram-positive and Gram-negative bacteria, yeast (Candida albicans) and fungus (Aspergillus fumigatus).

  4. Small Molecular White Organic Light Emitting Devices with Single Emission Zone

    NASA Astrophysics Data System (ADS)

    Duan, Yu; Jiang, Wenlong; Li, Jiang; Chen, Gang; Zhao, Yi; Hou, Jingying; Liu, Shiyong

    2004-11-01

    An organic white-light-emitting device has been demonstrated by mixing two colors from a single emissive layer. The device structure included indium tin oxide glass (ITO) substrate/30 nm 4,4',4''-tris{N,-(3-methylphenyl)-N-phenylamino}triphenylamine (m-MTDATA) as hole injection layer/10 nm N,N-diphenyl-N,N-bis1-naphthy l-1,1-biphenyl-4,4-diamine (NPB) as hole transparent layer/30 nm bis [2-(2-hydroxyphenyl)-pyridine]beryllium (Bepp2) doped with 0.2% rubrene as emitting layer/40 nm tris-8-hydroxyquinoline aluminum (Alq3) as electron transport layer/0.8 nm LiF/aluminum (Al). A stable white emission Commission Internationale de 1’Eclairage (CIE) chromaticity coordinate range from (0.38, 0.36) to (0.31, 0.31) for forward bias voltage which changing from 6 to 17 V has been achieved. Its maximum luminance was 29000 cd/m2 at 15v, and the maximum power and current efficiencies were 3.0 lm/W at 5 V and 6.3 cd/A at 7 V, respectively.

  5. 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. PMID:26137864

  6. 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. PMID:22919351

  7. Hydroxyapatite microparticles as feedback-active reservoirs of corrosion inhibitors.

    PubMed

    Snihirova, D; Lamaka, S V; Taryba, M; Salak, A N; Kallip, S; Zheludkevich, M L; Ferreira, M G S; Montemor, M F

    2010-11-01

    This work contributes to the development of new feedback-active anticorrosion systems. Inhibitor-doped hydroxyapatite microparticles (HAP) are used as reservoirs, storing corrosion inhibitor to be released on demand. Release of the entrapped inhibitor is triggered by redox reactions associated with the corrosion process. HAP were used as reservoirs for several inhibiting species: cerium(III), lanthanum(III), salicylaldoxime, and 8-hydroxyquinoline. These species are effective corrosion inhibitors for a 2024 aluminum alloy (AA2024), used here as a model metallic substrate. Dissolution of the microparticles and release of the inhibitor are triggered by local acidification resulting from the anodic half-reaction during corrosion of AA2024. Calculated values and experimentally measured local acidification over the aluminum anode (down to pH = 3.65) are presented. The anticorrosion properties of inhibitor-doped HAP were assessed using electrochemical impedance spectroscopy. The microparticles impregnated with the corrosion inhibitors were introduced into a hybrid silica-zirconia sol-gel film, acting as a thin protective coating for AA2024, an alloy used for aeronautical applications. The protective properties of the sol-gel films were improved by the addition of HAP, proving their applicability as submicrometer-sized reservoirs of corrosion inhibitors for active anticorrosion coatings. PMID:20942404

  8. 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.

  9. 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

  10. 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.

  11. Hygiene in the prevention of udder infections. IV. Evaluation of teat dips with excised cows' teats.

    PubMed

    Philpot, W N; Boddie, R L; Pankey, J W

    1978-07-01

    Suspensions of Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli, and Pseudomonas aeruginosa were used to contaminate teats excised from cows. Commercially available teat dips were applied for evaluation of comparative germicidal activity. Iodophors, sodium hypochlorite, and sodium dichloro-s-triazenetrione were highly effective against all four test organisms. Quarternary ammonium, chlorhexidine, and cetylpyridinium chloride were effective against Staphylococcus aureus, and Streptococcus agalactiae but not Escherichia coli and Pseudomonas aeruginosa. Bronopol and 8-hydroxyquinoline sulfate were marginally effective on the two Gram positive organisms and ineffective on the two Gram negatives. Three of the dips were ineffective against all four pathogens; two were in nonaqueous bases, and the other was a blend of pine oil and antibodies with udder origin. In other trials, iodophor at .3% titratable iodine was highly effective against Staphylococcus aureus and Streptococcus agalactiae. Products containing .5 and 1% iodophor maintained effectiveness after each was used to dip 140 teats under conditions of commercial dairying. Logarithmic reduction in the geometric mean number of organisms recovered from teats was more meaningful for evaluating data than percent reduction. PMID:100535

  12. Biocidal activity of some Mannich base cationic derivatives.

    PubMed

    Negm, Nabel A; Morsy, Salwa M I; Said, Medhat M

    2005-11-01

    A novel series of cationic surfactants was prepared based on Mannich base (produced from the condensation of piperidine and/or morpholine as secondary amine and paraformaldehyde in the presence of 8-hydroxyquinoline). The chemical structures of the synthesized cationic surfactants were confirmed using elemental analyses, FTIR spectroscopy and 1H NMR. Surface activities of the prepared surfactants were measured including: surface tension (gamma), critical micelle concentration (CMC), effectiveness (pi(CMC)), efficiency (Pc20), maximum surface excess (Gamma(max)), minimum surface area (A(min)), interfacial tension (gamma(IT)), emulsification power and foaming power at 25 degrees C. The structural influences on their surface activities and adsorption free energy were discussed. The synthesized cationic surfactants were evaluated for their biocidal activity towards Gram +ve bacteria (Staph. Cocu., Bacillus), Gram -ve bacteria (Salmonella, E. coli), fungi (A. terrus., A. flav.) and yeast (Candida) at 1.0, 2.5 and 5.0mg/mL, respectively. The target compounds showed good inhibition towards Gram +ve bacteria, Gram -ve bacteria and yeast. Meanwhile, excellent fungicidal results were obtained against the various types of fungi under investigation. PMID:16154748

  13. 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.

  14. 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

  15. Light-emitting carbazole derivatives for electroluminescent materials

    NASA Astrophysics Data System (ADS)

    Lin, Jiann T.; Thomas, K. R. J.; Tao, Yu-Tai; Ko, Chung-Wen

    2002-02-01

    Amorphous carbazole derivatives containing peripheral diarylamines at the 3- and 6-positions and an ethyl or aryl substituent at the 9-position of the carbazole moiety have been synthesized. These new carbazole compounds (carbs) possess high glass transition temperatures (Tg: 120- 194 degree(s)C) and high thermal decomposition temperatures (Td>450 degree(s)C). The compounds are weakly to moderately luminescent with the emission wavelength ranging from green to blue. Two types of light-emitting diodes (LED) were constructed from carb:(I)ITO/carb/TPBI/Mg:Ag and (II)ITO/carb/Alq3/Mg:Ag, where TPBI and Alq3 are 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene and tris(8- hydroxyquinoline) aluminum, respectively. In type I devices the carb functions as the hole-transporting as well as emitting material. In type II devices either carb and/or Alq3 is the light emitting material. Several green light-emitting devices exhibit exceptional maximum brightness and the physical performance is superior to those of typical green-light-emitting devices of the structure ITO/diamine/Alq3/Mg:Ag. Relation between the LUMO of the carb and the performance of the light-emitting diode is discussed.

  16. 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

  17. 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

  18. 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

  19. 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

  20. Red electrophosphorescence from a soluble binaphthol derivative as host and iridium complex as guest.

    PubMed

    Gong, Xiong; Benmansour, Hadjar; Bazan, Guillermo C; Heeger, Alan J

    2006-04-13

    The investigation of the optical properties, carrier injection, and transport into a soluble small molecule, 6,6'-dicarbazolyl-2,2'-dihexyloxy-1,1'-binaphthol (BA), was reported. The results demonstrated that BA is a blue-emitting molecule, which can be used as a host for the fabrication of electrophosphorescent light-emitting diodes (LEDs). The single-layer electrophosphorescent LEDs fabricated from toluene solution containing BA with tris[2,5-bis-2'-(9',9'-dihexylfluorene)pyridine-kappa(2)NC(3)(')]iridium(III) [Ir(HFP)(3)] emitted red light from Ir(HFP)(3) triplet emission. The results from photoluminescence (PL) and electroluminescence (EL) demonstrated that the dominated operational mechanism in EL was charge trapping rather than Förster transfer, which was the dominated mechanism in PL. The single-layer OLEDs with 1wt % of Ir(HFP)(3) have a luminance (L) of 1000 cd/m(2) at 22 V and a luminous efficiency (LE) of 0.88 cd/A at 11 mA/cm(2). Double-layer electrophosphorescent LEDs fabricated by casting the emitting layer from a solution of BA blended with Ir(HFP)(3) and subsequently thermally depositing tris(8-hydroxyquinoline) aluminum (Alq(3)) film as an electron injection and transport layer yielded L = 1830 cd/m(2) at 30 V and LE = 2.47 cd/A at 18 mA/cm(2). These results demonstrated that electrophosphorescent LEDs can be fabricated from BA via solution processing and that L and LE can be enhanced by changing the device architecture with the goal of better balancing the electron and hole currents. PMID:16599508

  1. 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

  2. Tuning hole-injection barriers at organic/metal interfaces exploiting the orientation of a molecular acceptor interlayer

    NASA Astrophysics Data System (ADS)

    Niederhausen, J.; Amsalem, P.; Frisch, J.; Wilke, A.; Vollmer, A.; Rieger, R.; Müllen, K.; Rabe, J. P.; Koch, N.

    2011-10-01

    Ultraviolet photoelectron spectroscopy was used to demonstrate organic/metal-contact charge injection barrier tuning by exploiting the orientation-dependent work function ϕ of a molecular acceptor [hexaazatriphenylene-hexanitrile (HATCN)] interlayer on Ag(111). The work function ϕ of a flat-lying HATCN monolayer on Ag was 4.6 eV (similar to a pristine Ag electrode), whereas a layer of edge-on HATCN on Ag exhibited ϕ of 5.5 eV (comparable to a pristine Au electrode). The hole-injection barriers (HIBs) between HATCN-modified electrodes and the organic semiconductors tris(8-hydroxyquinoline)aluminum (Alq3) and N,N'-bis(1-naphtyhl)-N,N'-diphenyl-1,1'-biphenyl-4.4'-diamine (α-NPD) were reduced by more than 1 eV compared to pristine Ag and Au electrodes. Noteworthy, the HIBs determined with the flat-lying HATCN interlayer were lower than those obtained for pristine Ag substrates (ϕ of both electrodes is 4.6 eV), and the HIBs with the edge-on HATCN on Ag were lower than those found for pristine Au (ϕ of both electrodes ca. 5.4 eV). This shows that acceptor interlayers are beneficial for charge injection in electronic devices even when the molecularly modified electrode ϕ is comparable to that of a pristine metal surface. It is argued that the molecularly modified electrodes are electronically more rigid than their pristine metal counterparts, i.e., the electron spill-out at the organic-terminated surface is less pronounced compared to Ag and Au surfaces.

  3. Synthesis of a monofunctional platinum compound and its activity alone and in combination with phytochemicals in ovarian tumor models.

    PubMed

    Arzuman, Laila; Beale, Philip; Yu, Jun Qing; Proschogo, Nick; Huq, Fazlul

    2014-12-01

    Currently used platinum drugs fail to provide long-term cure for ovarian cancer mainly because of acquired drug resistance. In this study, a new monofunctional planaramineplatinum(II) complex, namely tris(8-hydroxyquinoline)monochloroplatinum(II) chloride (coded as LH3), was synthesised and investigated for its activity against human ovarian A2780, cisplatin-resistant A2780 (A2780(cisR)) and ZD0473-resistant A2780 (A2780(ZD0473R)) cancer cell lines, alone and in combination with the phytochemicals curcumin, genistein and resveratrol. Cellular levels of glutathione in A2780 and A2780(cisR) cell lines before and after treatment with LH3 and its combinations with genistein and curcumin were also determined. Interaction of the compounds with salmon sperm DNA, pBR322 plasmid DNA and damage to DNA in A2780 and A2780(cisR) cells due to interaction with LH3-alone and in combination with phytochemicals were also investigated. LH3 was found to be much more active than cisplatin against the resistant tumor models and greatest synergism in activity was observed when combinations of LH3 with genistein and curcumin were administered as a bolus. For combinations of LH3 with the phytochemicals, platinum accumulation and the level of Pt-DNA binding were found to be greater in the resistant A2780(cisR) cell line than in the parental A2780 cell line. Greater activity of LH3 than cisplatin against the resistant ovarian cell lines indicates that it may have the potential for development as a novel anticancer drug and that its combination with phytochemicals can serve to further enhance drug efficacy. PMID:25503135

  4. 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

  5. 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

  6. 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

  7. Effects of novel neuroprotective and neurorestorative multifunctional drugs on iron chelation and glucose metabolism.

    PubMed

    Pollak, Yulia; Mechlovich, Danit; Amit, Tamar; Bar-Am, Orit; Manov, Irena; Mandel, Silvia A; Weinreb, Orly; Meyron-Holtz, Esther G; Iancu, Theodore C; Youdim, Moussa B H

    2013-01-01

    Iron accumulation and iron-related oxidative stress are involved in several pathological conditions and provide a rationale for the development of iron chelators as novel promising therapeutic strategies. Thus, we have recently synthesized multifunctional non-toxic, brain permeable iron chelating compounds, M30 and HLA20, possessing the neuroprotective N-propargyl moiety of the anti-Parkinsonian drug, monoamine oxidase (MAO)-B inhibitor, rasagiline and the antioxidant-iron chelating moiety of an 8-hydroxyquinoline derivative of the iron chelator, VK28. Here, we examined the hepatic regulatory effects of these novel compounds using two experimental approaches: chelation activity and glucose metabolism parameters. The present study demonstrated that M30 and HLA20 significantly decreased intracellular iron content and reduced ferritin expression levels in iron-loaded hepatoma Hep3B cells. In electron microscopy analysis, M30 was shown to reduce the electron-dense deposits of siderosomes by ~30 %, as well as down-regulate cytosolic ferritin particles observed in iron-overloaded cells. In vivo studies demonstrated that M30 administration (1 mg/kg, P.O. three times a week) reduced hepatic ferritin levels; increased hepatic insulin receptor and glucose transporter-1 levels and improved glucose tolerance in C57BL/6 mice and in a mouse model of type-2 diabetes, the ob/ob (leptin(-/-)). The results clearly indicate that the novel multifunctional drugs, especially M30, display significant capacity of chelating intracellular iron and regulating glucose metabolism parameters. Such effects can have therapeutic significance in conditions with abnormal local or systemic iron metabolism, including neurological diseases. PMID:22446839

  8. Efficient implementation of core-excitation Bethe-Salpeter equation calculations

    NASA Astrophysics Data System (ADS)

    Gilmore, K.; Vinson, John; Shirley, E. L.; Prendergast, D.; Pemmaraju, C. D.; Kas, J. J.; Vila, F. D.; Rehr, J. J.

    2015-12-01

    We present an efficient implementation of the Bethe-Salpeter equation (BSE) method for obtaining core-level spectra including X-ray absorption (XAS), X-ray emission (XES), and both resonant and non-resonant inelastic X-ray scattering spectra (N/RIXS). Calculations are based on density functional theory (DFT) electronic structures generated either by ABINIT or QuantumESPRESSO, both plane-wave basis, pseudopotential codes. This electronic structure is improved through the inclusion of a GW self energy. The projector augmented wave technique is used to evaluate transition matrix elements between core-level and band states. Final two-particle scattering states are obtained with the NIST core-level BSE solver (NBSE). We have previously reported this implementation, which we refer to as OCEAN (Obtaining Core Excitations from Ab initio electronic structure and NBSE) (Vinson et al., 2011). Here, we present additional efficiencies that enable us to evaluate spectra for systems ten times larger than previously possible; containing up to a few thousand electrons. These improvements include the implementation of optimal basis functions that reduce the cost of the initial DFT calculations, more complete parallelization of the screening calculation and of the action of the BSE Hamiltonian, and various memory reductions. Scaling is demonstrated on supercells of SrTiO3 and example spectra for the organic light emitting molecule Tris-(8-hydroxyquinoline)aluminum (Alq3) are presented. The ability to perform large-scale spectral calculations is particularly advantageous for investigating dilute or non-periodic systems such as doped materials, amorphous systems, or complex nano-structures.

  9. Highly selective and sensitive fluorescent paper sensor for nitroaromatic explosive detection.

    PubMed

    Ma, Yingxin; Li, Hao; Peng, Shan; Wang, Leyu

    2012-10-01

    Rapid, sensitive, and selective detection of explosives such as 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrophenol (TNP), especially using a facile paper sensor, is in high demand for homeland security and public safety. Although many strategies have been successfully developed for the detection of TNT, it is not easy to differentiate the influence from TNP. Also, few methods were demonstrated for the selective detection of TNP. In this work, via a facile and versatile method, 8-hydroxyquinoline aluminum (Alq(3))-based bluish green fluorescent composite nanospheres were successfully synthesized through self-assembly under vigorous stirring and ultrasonic treatment. These polymer-coated nanocomposites are not only water-stable but also highly luminescent. Based on the dramatic and selective fluorescence quenching of the nanocomposites via adding TNP into the aqueous solution, a sensitive and robust platform was developed for visual detection of TNP in the mixture of nitroaromatics including TNT, 2,4-dinitrotoluene (DNT), and nitrobenzene (NB). Meanwhile, the fluorescence intensity is proportional to the concentration of TNP in the range of 0.05-7.0 μg/mL with the 3σ limit of detection of 32.3 ng/mL. By handwriting or finger printing with TNP solution as ink on the filter paper soaked with the fluorescent nanocomposites, the bluish green fluorescence was instantly and dramatically quenched and the dark patterns were left on the paper. Therefore, a convenient and rapid paper sensor for TNP-selective detection was fabricated. PMID:22946839

  10. 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.

  11. 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

  12. 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

  13. EFFECT OF CHELATING AGENTS ON THE GROWTH OF ESCHERICHIA COLI IN SEAWATER1

    PubMed Central

    Jones, Galen E.

    1964-01-01

    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, NH4Cl, and K2HPO4). 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 10−5m 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 Na2S2O3, Na2S, 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

  14. Brain catalase in the streptozotocin-rat model of sporadic Alzheimer's disease treated with the iron chelator-monoamine oxidase inhibitor, M30.

    PubMed

    Sofic, E; Salkovic-Petrisic, M; Tahirovic, I; Sapcanin, A; Mandel, S; Youdim, M; Riederer, P

    2015-04-01

    Low intracerebroventricular (icv) doses of streptozotocin (STZ) produce regionally specific brain neurochemical changes in rats that are similar to those found in the brain of patients with sporadic Alzheimer's disease (sAD). Since oxidative stress is thought to be one of the major pathologic processes in sAD, catalase (CAT) activity was estimated in the regional brain tissue of animals treated intracerebroventricularly with STZ and the multitarget iron chelator, antioxidant and MAO-inhibitor M30 [5-(N-methyl-N-propargylaminomethyl)-8-hydroxyquinoline]. Five-day oral pre-treatment of adult male Wistar rats with 10 mg/kg/day M30 dose was followed by a single injection of STZ (1 mg/kg, icv). CAT activity was measured colorimetrically in the hippocampus (HPC), brain stem (BS) and cerebellum (CB) of the control, STZ-, M30- and STZ + M30-treated rats, respectively, 4 weeks after the STZ treatment. STZ-treated rats demonstrated significantly lower CAT activity in all three brain regions in comparison to the controls (p < 0.05 for BS and CB, p < 0.01 for HPC). M30 pre-treatment of the control rats did not influence the CAT activity in HPC and CB, but significantly increased it in BS (p < 0.05). M30 pre-treatment of STZ-treated rats significantly increased CAT activity in the HPC in comparison to the STZ treatment alone (p < 0.05) and normalized to the control values. These findings are in line with the assumption that reactive oxygen species contribute to the pathogenesis of STZ in a rat model of sAD and indicate that multifunctional iron chelators such as M30 might also have beneficial effects in this non-transgenic sAD model. PMID:25252744

  15. Phase transfer hollow fiber liquid phase microextraction combined with electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of trace heavy metals in environmental and biological samples.

    PubMed

    Guo, Xueqin; He, Man; Chen, Beibei; Hu, Bin

    2012-11-15

    A new method of phase transfer hollow fiber liquid phase microextraction (PT-HF-LPME) combined with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) has been developed for the determination of trace Co, Pd, Cd and Bi in environmental and biological samples. In PT-HF-LPME, an intermediate solvent (1-butanol) was added into the sample solution to ensure the maximum contact area between the target metal ions and the chelating reagent (8-hydroxyquinoline, 8-HQ), which accelerated the formation of 8-HQ-metal complexes and their subsequent extraction by extraction solvent (toluene). The experimental parameters affecting the extraction efficiency of PT-HF-LPME for the target metals were studied by simplex optimization and orthogonal array design (OAD) experiments. Under the optimized conditions, the enrichment factors for Co, Pd, Cd and Bi were 110, 393, 121 and 111-fold, respectively, the limits of detection (LODs, 3σ) ranged from 3.7 to 8.3 ng L(-1). The relative standard deviations (RSDs, c=0.5 ng mL(-1), n=7) were 8.7, 6.2, 12.4 and 12.9% for Co, Pd, Cd and Bi, respectively. To validate the accuracy of the proposed method, two Certified Reference Materials of GSBZ50009-88 Environment Water and GBW09103 Human Urine were analyzed, and the results obtained for Cd were in good agreement with the certified values. Finally, the developed method was successfully applied to the analysis of Co, Pd, Cd and Bi in lake water and human urine samples. PMID:23158357

  16. 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

  17. Partial purification and some properties of a latent CO2 reductase from green potato tuber chloroplasts.

    PubMed

    Arora, S; Ramaswamy, N K; Nair, P M

    1985-12-16

    We have partially purified the CO2 reductase, present in green potato tuber chloroplasts, as a latent form. Illumination of the chloroplasts in the absence of substrate, bicarbonate, activated the enzyme, which could then be obtained in soluble forms. Purification of the enzyme was achieved by (NH4)2SO4 fractionation (0-30%) and adsorption and elution from a DEAE-Sephadex A-50 column. The final preparation showed 15-fold purification and 50% recovery of the activity. The pH optimum for CO2 reductase was 8.0. Hepes and Tricine buffers showed maximum activity whereas Tris/phosphate or borate failed to show any activity. The enzyme reaction was sensitive to the presence of metal ions like Fe3+, Hg2+, Cu2+, Mo6+ and Zn2+, however, a threefold activation was observed with Fe2+. The metal requirement for CO2 reductase was evident from the observed inhibition by metal chelators like o-phenanthroline, alpha, alpha'-dipyridyl, bathocuproine, 8-hydroxyquinoline etc. Out of these o-phenanthroline was the strongest inhibitor and its concentration for 50% inhibition was 40 microM. The presence of Fe2+ ions in the reaction mixture protected the enzyme from heat denaturation upto 50 degrees C. Maximum enzyme activity was observed at 15 degrees C. The enzyme activity showed a 30-s lag period and the maximum was reached in 90 s. Supplementation of sodium dithionite in the reaction activated enzyme activity threefold, suggesting involvement of dithiol groups in the catalytic activity. There was strong inhibition by -SH inhibitors like 5,5'-dithiobis(2-nitrobenzoic acid) and N-ethylmaleimide and -SH reagents like dithiothreitol, 2-mercaptoethanol and cysteine. Various nucleotide coenzyme tried inhibited the enzyme strongly. PMID:3841062

  18. Streptomyces sp. JS520 produces exceptionally high quantities of undecylprodigiosin with antibacterial, antioxidative, and UV-protective properties.

    PubMed

    Stankovic, Nada; Radulovic, Vanja; Petkovic, Milos; Vuckovic, Ivan; Jadranin, Milka; Vasiljevic, Branka; Nikodinovic-Runic, Jasmina

    2012-12-01

    A Gram-positive, red-pigment-producing bacterial strain, designated JS520 was isolated from the pristine sediment from the cave on mountain Miroc in Serbia. Strain was confirmed to belong to Streptomyces genus based on phenotypic and genetic analysis. Streptomyces sp. JS520 has the ability to produce exceptionally high amounts of deep red pigment into both solid and liquid media. Liquid chromatography and mass spectroscopy of the purified pigments revealed the major component to be undecylprodigiosin (93 %) with minor component being oxidatively cyclized derivative. The pigment production was affected by medium composition, temperature, pH, and the aeration rate. By medium optimization, yields of undecylprodigiosin of 138 mg l(-1) were achieved, what is the highest level of undecylprodigiosin production reported for the members of Gram-positive Streptomyces genus. Purified pigment had antimicrobial properties against bacterial Bacillus and Micrococcus species (50 μg ml(-1)) and against Candida albicans species (100-200 μg ml(-1) range). The ability to affect auto-oxidation of the linoleic acid was demonstrated for the purified undecylprodigiosin, suggesting antioxidative properties of this pigment. Multiple ecophysiological roles of the pigment were revealed by comparing cultures grown under pigment-producing and pigment-nonproducing conditions. Cells grown under undecylprodigiosin-producing conditions could tolerate presence of hydrogen peroxide exhibiting three times smaller zones of inhibition at 100 mM H(2)O(2). Undecylprodigiosin-producing cells were also less susceptible to tetracycline, kanamycin, chloramphenicol, and 8-hydroxyquinoline. While the growth of the cells not producing pigment was completely inhibited by 15 min of exposure to ultraviolet light (254 nm), cells producing undecylprodigiosin and cells supplied with purified pigment in vitro showed survival rates at 22 and 8 %, respectively. PMID:22767180

  19. Hole transporting material 5, 10, 15-tribenzyl-5H-diindolo[3, 2-a:3‧, 2‧-c]-carbazole for efficient optoelectronic applications as an active layer

    NASA Astrophysics Data System (ADS)

    Zheng, Yan-Qiong; J. Potscavage, William, Jr.; Zhang, Jian-Hua; Wei, Bin; Huang, Rong-Juan

    2015-02-01

    In order to explore the novel application of the transparent hole-transporting material 5,10,15-tribenzyl-5H-diindolo[3,2-a:3‧,2‧-c]-carbazole (TBDI), in this article TBDI is used as an active layer but not a buffer layer in a photodetector (PD), organic light-emitting diode (OLED), and organic photovoltaic cell (OPV) for the first time. Firstly, the absorption and emission spectra of a blend layer comprised of TBDI and electron-transporting material bis-(2-methyl-8-quinolinate) 4-phenylphenolate (BAlq) are investigated. Based on the absorption properties, an organic PD with a peak absorption at 320 nm is fabricated, and a relatively-high detectivity of 2.44 × 1011 cm·Hz1/2/W under 320-nm illumination is obtained. The TBDI/tris (8-hydroxyquinoline) aluminum (Alq3) OLED device exhibits a comparable external quantum efficiency and current efficiency to a traditional 4, 4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD)/Alq3 OLED. A C70-based Schottky junction with 5 wt%-TBDI yields a power conversion efficiency of 5.0%, which is much higher than 1.7% for an α-NPD-based junction in the same configuration. These results suggest that TBDI has some promising properties which are in favor of the hole-transporting in Schottky junctions with a low-concentration donor. Project supported by the Funding Program for World-Leading Innovative R & D on Science and Technology (FIRST) from JSPS, the Fund from the Science and Technology Commission of Shanghai Municipality, China (Grant Nos. 14DZ2280900 and 14XD1401800), and the Natural Science Foundation of Shanghai (Grant No. 15ZR1416600).

  20. Large volume preconcentration and determination of nanomolar concentrations of iron in seawater using a renewable cellulose 8-hydroquinoline sorbent microcolumn and universal approach of post-column eluate utilization in a Lab-on-Valve system.

    PubMed

    Horstkotte, Burkhard; Chocholouš, Petr; Solich, Petr

    2016-04-01

    We report on a Lab-On-Valve (LOV) configuration for analyte preconcentration from milliliter sample volumes using confluent mixing in the holding coil for in-line addition of loading buffer. The system was applied to the spectrophotometric determination of iron(II) in acidified seawater using 1,10-phenanthroline as color reagent. A cellulose-based chelating sorbent containing 8-hydroxyquinoline was used for the first time in LOV and excellent retention behavior and loading capacity were found. The flow system employs a syringe pump for handling all solutions (sorbent suspension, loading buffer, water, eluent, and color reagent) and a peristaltic pump for sample propulsion and includes a fit-for-purpose 14 cm long detection glass flow cell and a bubble trap for in-line carrier degasification. Advantage was taken of the LOV flow-through port to keep the eluted analytes for re-aspiration for subsequent chromogenic reaction. In effect, a universal analyzer configuration and preconcentration procedure was developed, which is combinable with other analytes, sorbents, and reagents. Among the studied parameters were the compositions, pH, volumes, and flow rates of loading buffer, eluent, and color reagent, as well as the microcolumn size, repeatability, and system stability. Reproducibility of 4.1% RSD over the entire working range, a LOD of down to 5 nmol L(-1), sampling frequency of 12h(-1), and linearity up to 1 µmol L(-1) for 3.3 mL of sample were obtained and applicability to real samples was demonstrated. It was proven that both Fe(III) and Fe(II) were retained and yielded similar recovery and sensitivity values. The method was applied to coastal seawater samples and spiking experiments yielded recovery values close to 100%. PMID:26838402

  1. 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

    NASA Astrophysics Data System (ADS)

    Faheim, Abeer A.; Abdou, Safaa N.; Abd El-Wahab, Zeinab H.

    2013-03-01

    Salicylidene (4-aminotoluene-3-sulfonic acid) Schiff base ligand H2L, 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, 1H NMR, mass and solid reflectance), molar conductance, magnetic moment, TG-DSC measurements and XRPD analysis. Correlation of all spectroscopic data suggest that H2L 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.

  2. 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.

  3. 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.

  4. An Interplay Between Infrared Multiphoton Dissociation Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry and Density Functional Theory Computations in the Characterization of a Tripodal Quinolin-8-Olate Gd(III) Complex

    NASA Astrophysics Data System (ADS)

    De Bonis, Margherita; Bianco, Giuliana; Amati, Mario; Belviso, Sandra; Cataldi, Tommaso R. I.; Lelj, Francesco

    2013-04-01

    A new hexadentate, tripodal 8-hydroxyquinoline based ligand (QH3) and its gadolinium(III) tris-chelated (GdQ) complex with hemicage structure was investigated by using high resolution Fourier-transform ion cyclotron resonance mass spectrometry (FTICRMS). The protonated adduct of the free ligand and its hemicage tripodal Gd(III) complex, [GdQ + H]+, were first observed in experiments of electrospray ionization (ESI) with a linear ion trap (LTQ) mass spectrometer and further investigated by using high resolution FTICRMS. Gas-phase dissociation of the protonated Gd(III) complex, by infrared multiphoton dissociation (IRMPD) FTICR MS, demonstrated a fragmentation pattern with six main product cluster ions labeled as [Fn]+ ( n = 1 up to 6). These product ions suggest the elimination of 7-amino-alkyl or 7-alkyl chains of the hemicage moiety. High resolution MS conditions allowed the elucidation of the fragmentation pattern and product ion structures along with the determination, among the isotopic pattern of Gd, of the chemical compositions of closely related species, which differ in terms of hydrogen content. Among the Gd six naturally stable isotopes, 158Gd is the most abundant, and its peak within each cluster was used as a reference for distinguishing each product ions. Computational DFT investigations were applied to give support to some hypothesis of fragmentation pathways, which could not have been easily justified on the basis of the experimental work. Furthermore, computational studies suggested the coordination geometry of the protonated parent complex and the five- and four-coordinated complexes, which derive from its fragmentation. Furthermore, experimental and computational evidences were collected about the octet spin state of the parent compound.

  5. Speciation analysis of chromium by separation on a 5-palmitoyl oxine-functionalized XAD-2 resin and spectrophotometric determination with diphenylcarbazide.

    PubMed

    Filik, Hayati; Doğutan, Melek; Apak, Reşat

    2003-07-01

    The method developed in this work for the separation and preconcentration of Cr(III) is based on its retention by an Amberlite XAD-2 copolymer resin functionalized with 5-palmitoyl-8-hydroxyquinoline (oxine), abbreviated XAD-POx, with the ligand covalently bound to the copolymer. Cr(III) sorption was quantitative within the pH range 4.5-7.0 and Cr(VI) was not retained. The Cr(III) held by the resin column was eluted with a hot solution of H(2)O(2) in pH>or=9.0 aqueous NH(3)-NH(4)Cl buffer, and Cr oxidized to CrO(4)(2-) was rejected by the chelating cation-exchanger column. Any Cr(VI) originally present with Cr(III) could be reduced with an acidic solution of H(2)O(2), and retained by the column yielding total Cr results, Cr(VI) being determined from the difference. The resin showed a maximal preconcentration factor of 60 for Cr(III), the LOD and LOQ being 9.3 and 30.1 nmol L(-1), respectively. The developed preconcentration-speciation analysis was finished with a diphenylcarbazide (DPC) spectrophotometric procedure suitable for conventional laboratories. The resin showed excellent salt tolerance, enabling Cr analysis in seawater, and was stable over extended use. All the interferents of this procedure that normally occur in an electroplating effluent, a blended coal CRM, and a standard steel sample could be removed by the recommended procedure, by use of partial and total selectivity at the adsorption and desorption stages, respectively, enabling preconcentration and colorimetric determination of chromium in various complex matrices. PMID:12819851

  6. Optical properties of organic films, multilayers and plasmonic metal-organic waveguides fabricated by organic molecular beam deposition

    NASA Astrophysics Data System (ADS)

    Wickremasinghe, Niranjala D.

    In this thesis, the optical properties of tris (8-hydroxyquinoline) aluminum (Alq3) and 3,5,9,10-perylentetracarboxylic dianhydride (PTCDA) organic films, PTCDA/ Alq3 multilayers and plasmonic Alq3 -metal waveguides are investigated. The organic films and heterostructures used for this work were fabricated by organic molecular beam deposition (OMBD). We investigated the quenching of the light emission in Alq3 films grown on a Si substrate as a function of cw laser excitation intensity at varying temperatures from 15 to 300 K. The saturation of the singlet-singlet annihilation coefficient was measured with spectrally-integrated (SI) photoluminescence (PL) using a photodiode. The bimolecular quenching coefficient was further studied with time-resolved (TR) PL as a function of 100 fs pulse fluences. The PL quenching is attributed to the annihilation of trapped excitons at Alq3 nanocrystal grain boundaries. The saturation is explained by the limited density of available trapping states at the grain boundaries. Our interpretation is supported by structural investigations of ultrathin Alq3 films with atomic force microscopy (AFM), scanning electron microscopy (SEM) and by comparing the experimental data with calculations using a coupled rate equation model. The wavelength dispersion of the refractive indices of PTCDA and Alq 3 layers and of PTCDA/Alq3 multilayer waveguides grown on Pyrex substrates was investigated. The m-line technique, an evanescent prism coupling technique, was used to determine the layers' thickness and the in-plane (TE modes) and normal (TM modes) refractive indices. The potential for controlling the refractive index dispersion and anisotropy by tailored organic multilayer waveguides is discussed.

  7. 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

  8. 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

  9. 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

  10. Clioquinol-zinc chelate: a candidate causative agent of subacute myelo-optic neuropathy.

    PubMed Central

    Arbiser, J. L.; Kraeft, S. K.; van Leeuwen, R.; Hurwitz, S. J.; Selig, M.; Dickersin, G. R.; Flint, A.; Byers, H. R.; Chen, L. B.

    1998-01-01

    BACKGROUND: 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol) was used clinically three decades ago as an oral antiparasitic agent and to increase intestinal absorption of zinc in patients with acrodermatitis enteropathica, a genetic disorder of zinc absorption. Use of clioquinol was epidemiologically linked to subacute myelo-optic neuropathy (SMON), characterized by peripheral neuropathy and blindness, which affected 10,000 patients in Japan. Discontinuation of oral clioquinol use led to elimination of SMON, however, the mechanism of how clioquinol induces neurotoxicity is unclear. MATERIALS AND METHODS: We tested the effect of clioquinol-metal chelates on neural crest-derived melanoma cells. The effect of clioquinol chelates on cells was further studied by electron microscopy and by a mitochondrial potential-sensitive fluorescent dye. RESULTS: Of the ions tested, only clioquinol-zinc chelate demonstrated cytotoxicity. The cytotoxicity of clioquinol-zinc chelate was extremely rapid, suggesting that its primary effect was on the mitochondria. Electron microscopic analysis demonstrated that clioquinol-zinc chelate caused mitochondrial damage. This finding was further confirmed by the observation that clioquinol-zinc chelate caused a decrease in mitochondrial membrane potential. CONCLUSIONS: We demonstrate that clioquinol, in the presence of zinc, is converted to a potent mitochondrial toxin. The phenomenon of clioquinol mediated toxicity appears to be specific to zinc and is not seen with other metals tested. Since clioquinol has been shown to cause increased systemic absorption of zinc in humans, it is likely that clioquinol-zinc chelate was present in appreciable levels in patients with SMON and may be the ultimate causative toxin of SMON. Images Fig. 2 Fig. 3 PMID:9848083

  11. Effect of the electric field during annealing of organic light emitting diodes for improving its on/off ratio.

    PubMed

    Sharma, Rahul K; Katiyar, Monica; Rao, I V Kameshwar; Unni, K N Narayanan; Deepak

    2016-01-28

    If an organic light emitting diode is to be used as part of a matrix addressed array, it should exhibit low reverse leakage current. In this paper we present a method to improve the on/off ratio of such a diode by simultaneous application of heat and electric field post device fabrication. A green OLED with excellent current efficiency was seen to be suffering from a poor on/off ratio of 10(2). After examining several combinations of annealing along with the application of a reverse bias voltage, the on/off ratio of the same device could be increased by three orders of magnitude, specifically when the device was annealed at 80 °C under reverse bias (-15 V) followed by slow cooling also under the same bias. Simultaneously, the forward characteristics of the device were relatively unaffected. The reverse leakage in the OLED is mainly due to the injection of minority carriers in the hole transport layer (HTL) and the electron transport layer (ETL), in this case, of holes in tris-(8-hydroxyquinoline)aluminum(Alq3) and electrons in 4,4',4''-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA). Hence, to investigate these layers adjacent to the electrodes, we fabricated their single layer devices. The possibility of bulk traps present adjacent to electrodes providing states for injection was ruled out after estimating the trap density both before and after the reverse biased annealing. The temperature independent current in reverse bias ruled out the possibility of thermionic injection. The origin of the reverse bias current is attributed to the availability of interfacial hole levels in Alq3 at the cathode work function level in the as-fabricated device; the suppression of the same being attributed to the fact that these levels in Alq3 are partly removed after annealing under an electric field. PMID:26725927

  12. Synthesis, spectroscopic studies, molecular modeling and antimicrobial activity of binuclear Co(II) and Cu(II) complexes of 4,6-diacetylresorcinol

    NASA Astrophysics Data System (ADS)

    Shebl, Magdy; Khalil, Saied M. E.; Taha, A.; Mahdi, M. A. N.

    2013-09-01

    Reactions of 4,6-diacetylresorcinol with different cobalt(II) and copper(II) salts viz., OAc-, Cl-, NO3- and SO42-, yielded a new series of binuclear metal complexes. Reactions of the ligand with these metal ions in the presence of a secondary ligand (L‧) [O,O-donor; acetylacetone, N,O-donor; 8-hydroxyquinoline or N,N-donor; 1,10-phenanthroline and N,N,N‧,N‧-tetramethylethylenediamine] in 1:2:2 (L:M:L‧) molar ratio yielded mixed-ligand complexes with different molar ratios. The metal complexes were characterized by elemental and thermal analyses, IR, electronic, ESR and mass spectra as well as conductivity and magnetic susceptibility measurements. The analytical and spectroscopic data suggested that the H2L ligand behaves as a neutral, monobasic or dibasic tetradentate ligand, depending on the type of the anion and secondary ligand used, through the two phenolic and two carbonyl groups. Electronic spectra, magnetic and conductivity measurements showed that all complexes are octahedral with non-electrolytic nature. The profile of ESR spectra of copper(II) complexes suggested the octahedral geometry and the spin Hamiltonian parameters of the complexes were calculated and discussed. Molecular orbital calculations were performed for metal complexes using Hyperchem 7.52 program on the bases of PM3 level and the results correlated with the experimental data. The free ligand and some of its metal complexes showed antimicrobial activity towards some of Gram-positive and Gram-negative bacteria, yeast (Candida albicans) and fungus (Aspergillus fumigatus).

  13. Rat liver cysteine dioxygenase (cysteine oxidase). Further purification, characterization, and analysis of the activation and inactivation.

    PubMed

    Yamaguchi, K; Hosokawa, Y; Kohashi, N; Kori, Y; Sakakibara, S; Ueda, I

    1978-02-01

    Rat liver cysteine dioxygenase has been purified to homogeneity. It is a single subunit protein having a molecular weight of 22,500 +/- 1,000, with a pI of 5.5. The enzyme purified was catalytically inactive and activated by anaerobic incubation with either L-cysteine or its analogues such as carboxymethyl-L-cysteine, carboxyethyl-L-cysteine, S-methyl-L-cysteine, D-cysteine, cysteamine, N-acetyl-L-cysteine, and DL-homocysteine. The enzyme thus activated with L-cysteine was rapidly inactivated under aerobic condition. This rapid inactivation was observed at 0 degrees C where no formation of either the reaction product cysteine sulfinate or the autoxidation product of cysteine, cystine, was detected. Further analysis shows that the inactivation of the activated enzyme was due to oxygen but unrelated to either the presence of substrate, enzyme turnover or accumulation of inhibitor produced during assay. A distinct rat liver cytoplasmic protein, called protein-A, could completely prevented the enzyme from the aerobic inactivation. The loss of activity during assay in the absence of protein-A was shown to be a first order decay process. From the plots of log(deltaproduct/min) versus time, the initial velocity (VO) and the velocity at 7 min (V7) were obtained. The apparent Km value for L-cysteine in the absence of protein-A was calculated from the initial velocity as 4.5 X 10(-4)M. Protein-A did not alter the apparent Km value for L-cysteine. The chelating agents such as o-phenanthroline, alpha,alpha'-dipyridyl, bathophenanthroline, 8-hydroxyquinoline, EGTA, and EDTA strongly inhibited the enzyme activity when these chelating agents were added before preactivation. The purified cystein dioxygenase contains 1 atom of iron per mol of enzyme protein. By the activation procedure, the enzyme became less susceptible to the heat denaturation, the inhibitory effects of chelating agents and the tryptic digestion. PMID:632231

  14. Phosphonate ester hydrolysis catalyzed by two lanthanum ions. Intramolecular nucleophilic attack of coordinated hydroxide and lewis acid activation

    SciTech Connect

    Tsubouchi, A.; Bruice, T.C.

    1995-07-19

    (8-Hydroxy-2-quinolyl)methyl (8-hydroxy-2-quinolyl)methyl phosphonate (I) has been synthesized as a model compound and investigated in terms of catalysis of hydrolysis by two metal ions in concert. Removal of one of two 8-hydroxyquinoline ligands of I to provide (8-hydroxy-2-quinolyl)methylmethylphosphonate (II) leads to the formation of the 1:1 complex (II)La, which is hydrolytically inert but subject to catalysis by free La{sup 3+}. From thermodynamic studies of metal ion complexation and comparison of the kinetics of hydrolysis of I and II in the presence of metal ions, we conclude the following. The phosphonate ester I forms a hydrolytically active 1:2 complex (I)La{sub 2} with La{sup 3+} but inert 1:1 complexes with Zn{sup 2+}, Ni{sup 2+}, Co{sup 2+}, Cu{sup 2+}, and Al{sup 3+}. The La{sup 3+} in the (I)La{sub 2} complex serve to (i) facilitate the formation of metal ligated hydroxide as an intramolecule nucleophile; (ii) stabilize the transition state of the hydrolysis by neutralization of the phosphonate negative charge; and (iii) interact with an incipient oxyanion of the leaving alcohol. The two La{sup 3+} functions operate in concert and provide nearly 10{sup 13} rate enhancement. Consequently the 1:2 complex (I)La{sub 2}(OH{sub 2}){sub n-1}(OH) may serve as a model for the 3`-5` exonuclease reaction of E. coli DNA polymerase I. 39 refs., 7 figs., 3 tabs.

  15. Synthesis, spectroscopic studies, molecular modeling and antimicrobial activity of binuclear Co(II) and Cu(II) complexes of 4,6-diacetylresorcinol.

    PubMed

    Shebl, Magdy; Khalil, Saied M E; Taha, A; Mahdi, M A N

    2013-09-01

    Reactions of 4,6-diacetylresorcinol with different cobalt(II) and copper(II) salts viz., OAc(-), Cl(-), NO3(-) and SO4(2-), yielded a new series of binuclear metal complexes. Reactions of the ligand with these metal ions in the presence of a secondary ligand (L') [O,O-donor; acetylacetone, N,O-donor; 8-hydroxyquinoline or N,N-donor; 1,10-phenanthroline and N,N,N',N'-tetramethylethylenediamine] in 1:2:2 (L:M:L') molar ratio yielded mixed-ligand complexes with different molar ratios. The metal complexes were characterized by elemental and thermal analyses, IR, electronic, ESR and mass spectra as well as conductivity and magnetic susceptibility measurements. The analytical and spectroscopic data suggested that the H2L ligand behaves as a neutral, monobasic or dibasic tetradentate ligand, depending on the type of the anion and secondary ligand used, through the two phenolic and two carbonyl groups. Electronic spectra, magnetic and conductivity measurements showed that all complexes are octahedral with non-electrolytic nature. The profile of ESR spectra of copper(II) complexes suggested the octahedral geometry and the spin Hamiltonian parameters of the complexes were calculated and discussed. Molecular orbital calculations were performed for metal complexes using Hyperchem 7.52 program on the bases of PM3 level and the results correlated with the experimental data. The free ligand and some of its metal complexes showed antimicrobial activity towards some of Gram-positive and Gram-negative bacteria, yeast (Candida albicans) and fungus (Aspergillus fumigatus). PMID:23743042

  16. 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. PMID:23295217

  17. 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

  18. 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

  19. 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

  20. 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.

    PubMed

    Morita, Akinori; Ariyasu, Shinya; Wang, Bing; Asanuma, Tetsuo; Onoda, Takayoshi; Sawa, Akiko; Tanaka, Kaoru; Takahashi, Ippei; Togami, Shotaro; Nenoi, Mitsuru; Inaba, Toshiya; Aoki, Shin

    2014-08-01

    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 protected mice that had been exposed to a lethal dose of ionizing radiation. Our findings indicate that some types of bidentate 8HQ chelators could serve as radioprotectors with no substantial toxicity in vivo. PMID:25026551

  1. Gallium-68 chemistry for labeling platelets, proteins and lipoproteins

    SciTech Connect

    Yano, Y.; Budinger, T.F.; Ebbe, S.N.; Mathis, C.A.; Moore, D.H.; Singh, M.; Brennan, K.; Moyer, B.R.; Nichols, A.

    1984-07-01

    Generator produced gallium-68 is a convenient useful radionuclide for positron emission tomography (PET) investigations. Gallium-68 labeled platelets and low density lipoproteins would be useful agents for PET studies of thrombosis and atherosclerosis in cardiovascular disease. To label these agents with Ga-68, we have studied the effects of trace metal contaminants in 1 N HCl elutions of Ga-68 from germanium-68 absorbed on a stannic oxide column. Studies were conducted on the formation and characteristics of Ga-68 complexes with the ligands 8-hydroxyquinoline, tropolone, and mercaptopyridine-N-oxide (MPO). Various parameters such as pH, buffers, concentration of ligand, and incubation or stability with time were investigated. High performance liquid chromatography and instant thin layer chromatography were used to analyze the Ga-68 ligand preparations. Platelets separated from human, dog, and rabbit plasma were incubated with the Ga-68 complexes and the labeling yields and in vivo survival were determined. The accumulation of the platelets in the ballon catheter scraped aorta of the rabbit was determined by PET imaging studies, tissue counting in a gamma well counter, and en-face autoradiography of the arterial wall. The Ga-68 complexes of MPO gave 40 to 60% labeling efficiency of rabbit platelets which accumulated about fourfold more in the damaged aorta compared to the normal. Gallium-68 was attached to low density lipoproteins (LDL) with the bifunctional chelate of DTPA. Low pressure gel column chromatography and HPLC were used to preparatively separate and analyze the Ga-68 LDL for uptake studies in the healing endothelium of the scraped aorta rabbit model. The Ga-68 LDL labeling yield was 80 to 85% with a radiochemical purity 90 to 95%. 22 references, 10 figures, 4 tables.

  2. 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

  3. An OFF-ON chemosensor for biological and environmental applications: sensing Cd2+ in water using catanionic vesicles and in living cells.

    PubMed

    Bencini, Andrea; Caddeo, Francesco; Caltagirone, Claudia; Garau, Alessandra; Hurstouse, Mike B; Isaia, Francesco; Lampis, Sandrina; Lippolis, Vito; Lopez, Francesco; Meli, Valeria; Monduzzi, Maura; Mostallino, Maria Cristina; Murgia, Sergio; Puccioni, Stefano; Schmidt, Judith; Secci, Pietro Paolo; Talmon, Yeshayahu

    2013-11-28

    A new OFF-ON fluorescent chemosensor (L(1)) for Cd(2+) recognition based on a 5-chloro-8-hydroxyquinoline pendant arm derivative of 1,4,7-triazacyclononane ([9]aneN3) will be presented and its photochemical features in an MeCN-H2O 1 : 1 (v/v) mixture, in pure water, after inclusion within catanionic vesicles, and in living cells will be discussed. The coordination properties of L(1) both in solution and in the solid state were preliminarily studied and its selectivity towards Cd(2+)versus a set of different metal ions (Cu(2+), Zn(2+), Cd(2+), Pb(2+), Al(3+), Hg(2+), Co(2+), Ni(2+), Mn(2+), Mg(2+), K(+), Ca(2+), Ag(+), and Na(+)) was verified in MeCN-H2O 1 : 1 (v/v). In water, upon addition of increasing amounts of Cd(2+) to L(1) an enhancement of the fluorescence emission was detected. To overcome this serious drawback, L(1) was dissolved in an innovative catanionic vesicular solution based on sodium bis(2-ethylhexyl) sulfosuccinate, a traditional surfactant, and 1-dodecyl-3-methylimidazolium bromide, an ionic liquid. When enclosed within the vesicle bilayers in water, L(1) restored its fluorescence emission property upon addition of Cd(2+). Remarkably, L(1) enters the cellular membrane of living cells thus allowing the detection of intracellular Cd(2+). These findings encourage the application of this new fluorescent chemosensor in real samples for histological and environmental analyses. PMID:24113906

  4. 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

    2016-06-01

    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.

  5. Fast detection and quantification of Escherichia coli using the base principle of the microbial fuel cell.

    PubMed

    Kim, Taegyu; Han, Jong-In

    2013-11-30

    Escherichia coli is an important microbial indicator of fecal contamination, making accurate quantitative detection of E. coli a key to ensuring public health. In this study, a microbial fuel cell (MFC) was used as a detection unit of an E. coli sensor, and specific enzymes expressed in E. coli, such as β-D-galactosidase (GAL) and β-D-glucuronidase (GUS), were exploited as biological detection elements. As substrates, 4-aminophenyl-β-D-galactopyranoside (4-APGal) were used for GAL detection, whereas 8-hydroxyquinoline glucuronide (8-HQG) and 4-nitrophenyl β-D-glucuronide (PNPG) were used for GUS detection. Once these substrates were hydrolyzed by GAL or GUS, they became electrochemically active products, which were, in turn, oxidized on the anode of the MFC reactor. The power output of the MFC reactor increased sharply when E. coli in the reactor reached the critical concentration. Accordingly, the time required to reach the highest voltage output was recorded as a detection time (DT), and a negative linear relationship was established between DT and the logarithm of the initial concentration of E. coli in the samples studied. The DTs of laboratory samples were 140 min and 560 min for initial concentrations of 1.9 × 10(7) CFU/mL and 42 CFU/mL at 44.5 °C. Moreover, the DTs for GUS assays were further shortened by induction with methyl β-D-glucuronide sodium salt (MetGlu). The quantitative relationship between DTs and initial E. coli concentrations established from replicate laboratory sample assays allowed estimation of the E. coli concentration in environmental samples, but with approximately 100 min of lag time. The lag time was also observed with E. coli samples that were prepared by starving cells in a laboratory. PMID:24095789

  6. 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

  7. Ground state spectroscopy of hydroxyquinolines: evidence for the formation of protonated species in water-rich dioxane-water mixtures.

    PubMed

    Abou-Zied, Osama K; Husband, John; Al-Lawatia, Najla; Steinbrecher, Thomas B

    2014-01-01

    We have recently used 6-, 7-, and 8-hydroxyquinolines (HQs) as fluorescent probes to study the binding mechanism in one of the drug binding sites of human serum albumin. In the present work we study the absorption spectra of the HQ molecules in neat and binary mixtures of dioxane and water in order to identify the different tautomeric species in the ground state. This study should help in identifying the environment in nanocavities of macromolecules when HQs are used as local reporters. The enol form is shown to be the only tautomer for the three HQs in dioxane and water, with the exception of 7HQ in which both the enol and the zwitterion tautomers exist in equilibrium in water. The results are confirmed by the density functional theory (DFT) calculations using the B3LYP method with a 6-311++G(2d,p) basis set. In water-rich dioxane mixtures, all HQs are protonated. The results were confirmed by comparing the absorption spectra in binary solvents with those in acidic and basic aqueous solutions, and by DFT calculations of the Franck-Condon S1 ← S0 transitions. The number of water molecules solvating the polar sites in each HQ molecule was estimated from the spectral change in the binary solvent mixtures, and structures were calculated by DFT. Mapping the water density around the polar sites in each HQ using molecular dynamics (MD) simulations shows well-defined hydrogen bonds around the N-heteroatom in each HQ molecule. Water density is only well-defined around the hydroxyl group in 8HQ. The MD simulations indicate free rotation of the OH group in 6HQ and 7HQ, and the stability of the cis-isomer in 8HQ. The results point to the unique spectral signatures of 7HQ in water which make this molecule a potential probe to detect the presence of water in nanocavities of macromolecules, and to the ability of the three HQs to detect acidic media in binding sites. PMID:24158492

  8. Novel bimodal porous N-(2-aminoethyl)-3-aminopropyltrimethoxysilane-silica monolithic capillary microextraction and its application to the fractionation of aluminum in rainwater and fruit juice by electrothermal vaporization inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Zheng, Fei; Hu, Bin

    2008-01-01

    A novel bimodal porous N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AAPTS)-silica monolithic capillary was prepared by sol-gel technology, and used as capillary microextraction (CME) column for aluminum fractionation by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV)-ICP-MS with the use of polytetrafluoroethylene (PTFE) slurry as fluorinating agent. The extraction behaviors of different Al species were studied and it was found that in the pH range of 4-7, labile monomeric Al (free Al 3+, Al-OH and Al-F) could be retained quantitatively on the monolithic capillary, while non-labile monomeric Al (Al-Cit and Al-EDTA) passed through the capillary directly. The labile monomeric Al retained on monolithic capillary was eluted with 10 μL 1 mol L - 1 HCl and the elution was introduced into the ETV for fluorination assisted ETV-ICP-MS determination. The total monomeric Al fraction was also determined by AAPTS-silica monolithic CME-fluorination-assisted electrothermal vaporization (FETV)-ICP-MS after the sample solution was adjusted to pH 8.8. Non-labile monomeric Al was obtained by subtracting labile monomeric Al from the total monomeric Al. Under the optimized conditions, the relative standard deviation (R.S.D) was 6.2% ( C = 1 μg L - 1 , n = 7; sample volume, 5 mL), and the limit of detection was 1.6 ng L - 1 for Al with an enrichment factor of 436 fold and a sampling frequency of 9 h - 1 . The prepared AAPTS-silica monolithic capillary showed an excellent pH tolerance and solvent stability and could be used for more than 250 times without decreasing adsorption efficiency. The developed method was applied to the fraction of Al in rainwater and fruit juice, and the results demonstrated that the established system had advantages over the existing 8-hydroxyquinoline (8-HQ) chelating system for Al fractionation such as wider pH range, higher tolerance of interference and better regeneration.

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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.

  14. Synchrotron-based soft X-ray spectroscopic studies of the electronic structure of organic semiconducting molecules

    NASA Astrophysics Data System (ADS)

    Demasi, Alexander

    Organic molecules have been the subject of many scientific studies due to their potential for use in a new generation of optoelectronic and semiconducting devices, such as organic photovoltaics and organic light emitting diodes. These studies are motivated by the fact that organic semiconductor devices have several advantages over traditional inorganic semiconductor devices. Unlike inorganic semiconductors, where the electronic properties are a result of the deliberate introduction of dopants to the material, the properties of organic semiconductors are often intrinsic to the molecules themselves. As a result, organic semiconductor devices are frequently less susceptible to contamination by impurities than their inorganic counterparts, which results in the relatively lower cost of producing such devices. Accurate experimental determination of the bulk and surface electronic structure of organic semiconductors is a prerequisite in developing a comprehensive understanding of such materials. The organic materials studied in this thesis were N,N-Ethylene-bis(1,1,1trifluoropentane-2,4-dioneiminato)-copper(ii) (abbreviated Cu-TFAC), aluminum tris-8hydroxyquinoline (A1g3), lithium quinolate (Liq), tetracyanoquinodimethane (TCNQ), and tetrafluorotetracyanoquinodimethane (F4TCNQ). The electronic structures of these materials were measured with several synchrotron-based x-ray spectroscopies. X-ray photoemission spectroscopy was used to measure the occupied total density of states and the core-level states of the aforementioned materials. X-ray absorption spectroscopy (XAS) was used to probe the element-specific unoccupied partial density of states (PDOS); its angle-resolved variant was used to measure the orientation of the molecules in a film and, in some circumstances, to gauge the extent of an organic film's crystallinity. Most notably, x-ray emission spectroscopy (XES) measures the element- specific occupied PDOS and, when aided by XAS, resonant XES can additionally be

  15. 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

  16. 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

  17. Analysis of phosphate esters in plant material

    PubMed Central

    Isherwood, F. A.; Barrett, F. C.

    1967-01-01

    1. A critical study was made of the quantitative extraction of nucleotide and sugar phosphates from plant tissue by either boiling aqueous ethanol or cold trichloroacetic acid. The effect of the extraction technique on the inactivation of the enzymes in the plant tissue and the possibility of adsorption of the phosphate esters on the cell wall were especially considered. 2. In the recommended method the plant tissue was frozen in liquid nitrogen, ground to a powder and then blended with cold aqueous trichloroacetic acid containing 8-hydroxyquinoline to prevent adsorption. 3. The extract contained large amounts of trichloroacetic acid, cations, chloride, sugars, amino acids, hydroxy organic acids, phytic acid, orthophosphoric acid and high-molecular-weight material including some phosphorus-containing compounds. All of these were removed as they were liable to interfere with the chromatographic or enzymic assay of the individual nucleotide or sugar phosphates. 4. The procedure was as follows: the last traces of trichloroacetic acid were extracted with ether after the solution had been passed through a column of Dowex AG 50 in the hydrogen form to remove all cations. High-molecular-weight compounds were removed by ultrafiltration and low-molecular-weight solutes by a two-stage chromatography on cellulose columns with organic solvents. In the first stage, sugars, amino acids, chloride and phytic acid were separated by using a basic solvent (propan-1-ol–water–aqueous ammonia) and, in the second stage, the organic acids and orthophosphoric acid were separated by using an acidic solvent (di-isopropyl ether–formic acid–2-methylpropan-2-ol–water). The final solution of nucleotide and sugar phosphates was substantially free from other solutes and was suitable for the detection of individual phosphate esters by either chromatography or enzymic assay. 5. The recovery of d-glucose 6-phosphate or adenosine 5′-triphosphate added to a trichloroacetic acid extract

  18. Soft x-ray spectroscopic studies of the electronic structure of organic semiconductors

    NASA Astrophysics Data System (ADS)

    Zhang, Yufeng

    -ray scattering (RIXS) features. These observations and comparisons with other organic semiconductors, such as Tri (8-hydroxyquinoline) aluminum (Alq3), and metal oxides, such as V2O3, not only help to deepen our understanding of the optical and electrical properties of Pc's, but also provide valuable information for the studies of other materials.

  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

  20. 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