DNA-Binding Interaction Studies of Microwave Assisted Synthesized Sulfonamide Substituted 8-Hydroxyquinoline Derivatives.

PubMed

Dixit, Ritu B; Patel, Tarosh S; Vanparia, Satish F; Kunjadiya, Anju P; Keharia, Harish R; Dixit, Bharat C

2011-01-01

Sulfonamide substituted 8-hydroxyquinoline derivatives were prepared using a microwave synthesizer. The interaction of sulfonamide substituted 8-hydroxyquinoline derivatives and their transition metal complexes with Plasmid (pUC 19) DNA and Calf Thymus DNA were investigated by UV spectroscopic studies and gel electrophoresis measurements. The interaction between ligand/metal complexes and DNA was carried out by increasing the concentration of DNA from 0 to 12 μl in UV spectroscopic study, while the concentration of DNA in gel electrophoresis remained constant at 10 μl. These studies supported the fact that, the complex binds to DNA by intercalation via ligand into the base pairs of DNA. The relative binding efficacy of the complexes to DNA was much higher than the binding efficacy of ligands, especially the complex of Cu-AHQMBSH had the highest binding ability to DNA. The mobility of the bands decreased as the concentration of the complex was increased, indicating that there was increase in the interaction between the metal ion and DNA. Complexes of AHQMBSH were excellent for DNA binding as compared to HQMABS.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2013-12-04

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

Dispersive electron transport in tris(8-hydroxyquinoline) aluminum (Alq3) probed by impedance spectroscopy.

PubMed

Berleb, Stefan; Brütting, Wolfgang

2002-12-31

Electron transport in tris(8-hydroxyquinoline) aluminum (Alq3) is investigated by impedance spectroscopy under conditions of space-charge limited conduction (SCLC). Existing SCLC models are extended to include the field dependence of the charge carrier mobility and energetically distributed trap states. The dispersive nature of electron transport is revealed by a frequency-dependent mobility with a dispersion parameter alpha in the range 0.4-0.5, independent of temperature. This indicates that positional rather than energetic disorder is the dominant mechanism for the dispersive transport of electrons in Alq3.

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

Electronic structure and magnetism in transition metals doped 8-hydroxy-quinoline aluminum.

PubMed

Baik, Jeong Min; Shon, Yoon; Lee, Seung Joo; Jeong, Yoon Hee; Kang, Tae Won; Lee, Jong-Lam

2008-10-15

We report the room-temperature ferromagnetism in transition metals (Co, Ni)-doped 8-hydroxy-quinoline aluminum (Alq3) by thermal coevaporation of high purity metal and Alq3 powders. For 5% Co-doped Alq3, a maximum magnetization of approximately 0.33 microB/Co at 10 K was obtained and ferromagnetic behavior was observed up to 300 K. The Co atoms interact chemically with O atoms and provide electrons to Alq3, forming new states acting as electron trap sites. From this, it is suggested that ferromagnetism may be associated with the strong chemical interaction of Co atoms and Alq3 molecules.

High-efficiency tris(8-hydroxyquinoline)aluminum (Alq3) complexes for organic white-light-emitting diodes and solid-state lighting.

PubMed

Pérez-Bolívar, César; Takizawa, Shin-ya; Nishimura, Go; Montes, Victor A; Anzenbacher, Pavel

2011-08-08

Combinations of electron-withdrawing and -donating substituents on the 8-hydroxyquinoline ligand of the tris(8-hydroxyquinoline)aluminum (Alq(3)) complexes allow for control of the HOMO and LUMO energies and the HOMO-LUMO gap responsible for emission from the complexes. Here, we present a systematic study on tuning the emission and electroluminescence (EL) from Alq(3) complexes from the green to blue region. In this study, we explored the combination of electron-donating substituents on C4 and C6. Compounds 1-6 displayed the emission tuning between 478 and 526 nm, and fluorescence quantum yield between 0.15 and 0.57. The compounds 2-6 were used as emitters and hosts in organic light-emitting diodes (OLEDs). The highest OLED external quantum efficiency (EQE) observed was 4.6%, which is among the highest observed for Alq(3) complexes. Also, the compounds 3-5 were used as hosts for red phosphorescent dopants to obtain white light-emitting diodes (WOLED). The WOLEDs displayed high efficiency (EQE up to 19%) and high white color purity (color rendering index (CRI≈85). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improved luminescence intensity and stability of thermal annealed ZnO incorporated Alq3 composite films.

PubMed

Cuba, M; Muralidharan, G

2015-11-01

The 30 wt% of ZnO (weight percentage of ZnO has been optimised) incorporated tris- (8-hydroxyquinoline)aluminum (Alq3) has been synthesised and coated on to glass substrates using dip coating method. The structural and optical properties of the Alq3/ZnO composite film after thermal annealing from 50 to 300 °C insteps 50° has been studied and reported. XRD pattern reveals the presence of crystalline ZnO in all the annealed films. The films annealed above 150 °C reveal the presence of crystalline Alq3 along with crystalline ZnO. The FTIR spectra confirm the presence of hydroxyquinoline and ZnO vibration in all the annealed composite films. The composite films annealed above 150 °C show a partial sublimation and degradation of hydroxyquinoline compounds. The ZnO incorporated composite films (Alq3/ZnO) exhibit two emission peaks, one corresponding to ZnO at 487 nm and another at 513 nm due to Alq3. The films annealed at 200 °C exhibit maximum photoluminescence (PL) intensity than pristine film at 513 nm when excited at 390 nm.

8-hydroxyquinoline inhibition of DNA synthesis and intragenic recombination during yeast meiosis.

PubMed

Mills, D

1978-06-14

Complete inhibition of sporulation was observed in two strains of Saccharomyces cerevisiae to which 8-hydroxyquinoline was added at a final concentration of 5 microgram/ml during the initial 4 to 6 h of sporulation. The cells were most sensitive to the inhibitor during 4 to 6 interval beginning at approximately 2 h (T2). Its addition during that interval resulted in 70 to 80% lethality in strain 4579 and about 40% in API at T24. When present from T0 onward, 5 microgram/ml of 8-hydroxyquinoline severely inhibited premeiotic DNA replication and reduced the frequency of intragenic recombination at the ade 2 and leu 2 loci by 70 and 100%, respectively, relative to control cultures which did not have the inhibitor present. During the period when the cells were most sensitive, the incorporation of 14C-leucine into protein and 14C-adenine into RNA was not inhibited nor was the polysome content affected. At 150 microgram/ml of inhibitor, incorporation of labeled precursors into RNA and protein were inhibited and the percentage of active ribosomes was reduced by 35% within 45 min, but neither transcription or translation appeared to be completely inhibited at this concentration of the inhibitor.

New record of Scedosporium dehoogii from Chile: Phylogeny and susceptibility profiles to classic and novel putative antifungal agents.

PubMed

Alvarez, Eduardo; Sanhueza, Camila

Scedosporium species are considered emerging agents causing illness in immunocompromised patients. In Chile, only Scedosporium apiospermum, Scedosporium boydii and Lomentospora prolificans haven been reported previously. The study aimed to characterize genetically Scedosporium dehoogii strains from Chilean soil samples, and assessed the antifungal susceptibility profile to classic and novel putative antifungal molecules. In 2014, several samples were obtained during a survey of soil fungi in urban areas from Chile. Morphological and phylogenetic analyses of the internal transcribed spacer region (ITS), tubulin (TUB), and calmodulin (CAL) sequences were performed. In addition, the susceptibility profiles to classic antifungal and new putative antifungal molecules were determined. Four strains of Scedosporium dehoogii were isolated from soil samples. The methodology confirmed the species (reported here as a new record for Chile). Antifungal susceptibility testing demonstrates the low activity of terpenes (α-pinene and geraniol) against this species. Voriconazole (VRC), posaconazole (PSC), and the hydroxyquinolines (clioquinol, and 5,7-dibromo-8-hydroxyquinoline) showed the best antifungal activity. Our results demonstrate that Scedosporium dehoogii is present in soil samples from Chile. This study shows also that hydroxyquinolines have potential as putative antifungal molecules. Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

Unraveling the Mechanism of the Photodeprotection Reaction of 8-Bromo- and 8-Chloro-7-hydroxyquinoline Caged Acetates

PubMed Central

Ma, Jiani; Rea, Adam C; An, Huiying; Ma, Chensheng; Guan, Xiangguo; Li, Ming-De; Su, Tao; Yeung, Chi Shun; Harris, Kyle T; Zhu, Yue; Nganga, Jameil L; Fedoryak, Olesya D; Dore, Timothy M; Phillips, David Lee

2012-01-01

Abstract Photoremovable protecting groups (PPGs) when conjugated to biological effectors forming “caged compounds” are a powerful means to regulate the action of physiologically active messengers in vivo through 1-photon excitation (1PE) and 2-photon excitation (2PE). Understanding the photodeprotection mechanism is important for their physiological use. We compared the quantum efficiencies and product outcomes in different solvent and pH conditions for the photolysis reactions of (8-chloro-7-hydroxyquinolin-2-yl)methyl acetate (CHQ-OAc) and (8-bromo-7-hydroxyquinolin-2-yl)methyl acetate (BHQ-OAc), representatives of the quinoline class of phototriggers for biological use, and conducted nanosecond time-resolved spectroscopic studies using transient emission (ns-EM), transient absorption (ns-TA), transient resonance Raman (ns-TR2), and time-resolved resonance Raman (ns-TR3) spectroscopies. The results indicate differences in the photochemical mechanisms and product outcomes, and reveal that the triplet excited state is most likely on the pathway to the product and that dehalogenation competes with release of acetate from BHQ-OAc, but not CHQ-OAc. A high fluorescence quantum yield and a more efficient excited-state proton transfer (ESPT) in CHQ-OAc compared to BHQ-OAc explain the lower quantum efficiency of CHQ-OAc relative to BHQ-OAc. PMID:22511356

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.

Novel acid mono azo dye compound: Synthesis, characterization, vibrational, optical and theoretical investigations of 2-[(E)-(8-hydroxyquinolin-5-yl)-diazenyl]-4,5-dimethoxybenzoic acid

NASA Astrophysics Data System (ADS)

Saçmacı, Mustafa; Çavuş, Hatice Kanbur; Arı, Hatice; Şahingöz, Recep; Özpozan, Talat

2012-11-01

Novel acid mono azo dye, 2-[(E)-(8-hydroxyquinolin-5yl)-diazenyl]-4,5-dimethoxybenzoic acid (HQD), was synthesized by coupling diazonium salt solution of 2-amino-4,5-dimethoxybenzoic acid (DMA) with 8-hydroxyquinoline (HQ). This dye was characterized by UV-vis, IR & Raman, 1H and 13C NMR spectroscopic techniques and elemental analysis. The normal coordinate analysis of HQD was also performed to assign each band in vibrational spectra. DFT (B3LYP and B3PW91) calculations were employed to optimize the geometry, to interpret NMR spectra, to calculate and to determine the stable tautomeric structure of the compound. Natural Bond Orbital (NBO) analysis was performed to investigate intramolecular interactions. The vibrational spectral data obtained from solid phase IR & Raman spectra were assigned based on the results of the theoretical calculations. UV-vis spectroscopic technique was employed to obtain the optical band gap of HQD. The analysis of the optical absorption data revealed the existence of direct and indirect transitions in the optical band gaps. The optical band gaps of HQD have been found 1.95 and 1.90 eV for direct and indirect transitions, respectively.

Formation and Entrapment of Tris(8-hydroxyquinoline)aluminum from 8-Hydroxyquinoline in Anodic Porous Alumina

PubMed Central

Yamaguchi, Shohei; Matsui, Kazunori

2016-01-01

The formation and entrapment of tris(8-hydroxyquinoline)aluminum (Alq3) molecules on the surface of anodic porous alumina (APA) immersed in an ethanol solution of 8-hydroxyquinoline (HQ) were investigated by absorption, fluorescence, and Raman spectroscopies. The effects of the selected APA preparation conditions (galvanostatic or potentiostatic anodization method, anodizing current and voltage values, one- or two-step anodizing process, and sulfuric acid electrolyte concentration) on the adsorption and desorption of Alq3 species were examined. Among the listed parameters, sulfuric acid concentration was the most important factor in determining the Alq3 adsorption characteristics. The Alq3 content measured after desorption under galvanostatic conditions was 2.5 times larger than that obtained under potentiostatic ones, regardless of the adsorbed quantities. The obtained results suggest the existence of at least two types of adsorption sites on the APA surface characterized by different magnitudes of the Alq3 bonding strength. The related fluorescence spectra contained two peaks at wavelengths of 480 and 505 nm, which could be attributed to isolated Alq3 species inside nanovoids and aggregated Alq3 clusters in the pores of APA, respectively. The former species were attached to the adsorption sites with higher binding energies, whereas the latter ones were bound to the APA surface more weakly. Similar results were obtained for the Alq3 species formed from the HQ solution, which quantitatively exceeded the number of the Alq3 species adsorbed from the Alq3 solution. Alq3 molecules were formed in the HQ solution during the reaction of HQ molecules with the Al3+ ions in the oxide dissolution zone near the oxide/electrolyte interface through the cracks and the Al3+ ions adsorbed on surface of pore and cracks. In addition, it was suggested that HQ molecules could penetrate the nanovoids more easily than Alq3 species because of their smaller sizes, which resulted in higher magnitudes of the adsorption. PMID:28773840

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.

A matrix-focused structure-activity and binding site flexibility study of quinolinol inhibitors of botulinum neurotoxin serotype A.

PubMed

Harrell, William A; Vieira, Rebecca C; Ensel, Susan M; Montgomery, Vicki; Guernieri, Rebecca; Eccard, Vanessa S; Campbell, Yvette; Roxas-Duncan, Virginia; Cardellina, John H; Webb, Robert P; Smith, Leonard A

2017-02-01

Our initial discovery of 8-hydroxyquinoline inhibitors of BoNT/A and separation/testing of enantiomers of one of the more active leads indicated considerable flexibility in the binding site. We designed a limited study to investigate this flexibility and probe structure-activity relationships; utilizing the Betti reaction, a 36 compound matrix of quinolinol BoNT/A LC inhibitors was developed using three 8-hydroxyquinolines, three heteroaromatic amines, and four substituted benzaldehydes. This study has revealed some of the most effective quinolinol-based BoNT/A inhibitors to date, with 7 compounds displaying IC 50 values ⩽1μM and 11 effective at ⩽2μM in an ex vivo assay. Published by Elsevier Ltd.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Hongtao; Desai, P.; Kreouzis, T.

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 aremore » holes.« less

Effects of pure plant secondary metabolites on methane production, rumen fermentation and rumen bacteria populations in vitro.

PubMed

Joch, M; Mrázek, J; Skřivanová, E; Čermák, L; Marounek, M

2018-04-29

In this study, the effects of seven pure plant secondary metabolites (PSMs) on rumen fermentation, methane (CH 4 ) production and rumen bacterial community composition were determined. Two in vitro trials were conducted. In trial 1, nine concentrations of 8-hydroxyquinoline, α-terpineol, camphor, bornyl acetate, α-pinene, thymoquinone and thymol were incubated on separate days using in vitro 24-hr batch incubations. All compounds tested demonstrated the ability to alter rumen fermentation parameters and decrease CH 4 production. However, effective concentrations differed among individual PSMs. The lowest concentrations that reduced (p < .05) CH 4 production were as follows: 8 mg/L of 8-hydroxyquinoline, 120 mg/L of thymoquinone, 240 mg/L of thymol and 480 mg/L of α-terpineol, camphor, bornyl acetate and α-pinene. These concentrations were selected for use in trial 2. In trial 2, PSMs were incubated in one run. Methane was decreased (p < .05) by all PSMs at selected concentrations. However, only 8-hydroxyquinoline, bornyl acetate and thymoquinone decreased (p < .05) CH 4 relative to volatile fatty acids (VFAs). Based on denaturing gradient gel electrophoresis analysis, different PSMs changed the composition of bacterial communities to different extents. As revealed by Ion Torrent sequencing, the effects of PSMs on relative abundance were most pronounced in the predominant families, especially in Lachnospiraceae, Succinivibrionaceae, Prevotellaceae, unclassified Clostridiales and Ruminococcaceae. The CH 4 production was correlated negatively (-.72; p < .05) with relative abundance of Succinivibrionaceae and positively with relative abundance of Ruminococcaceae (.86; p < .05). In summary, this study identified three pure PSMs (8hydroxyquinoline, bornyl acetate and thymoquinone) with potentially promising effects on rumen CH 4 production. The PSMs tested in this study demonstrated considerable impact on rumen bacterial communities even at the lowest concentrations that decreased CH 4 production. The findings from this study may help to elucidate how PSMs affect rumen bacterial fermentation. © 2018 Blackwell Verlag GmbH.

Evaluation of 8-Hydroxyquinoline Derivatives as Hits for Antifungal Drug Design.

PubMed

Pippi, Bruna; Reginatto, Paula; Machado, Gabriella da Rosa Monte; Bergamo, Vanessa Zafaneli; Lana, Daiane Flores Dalla; Teixeira, Mario Lettieri; Franco, Lucas Lopardi; Alves, Ricardo José; Andrade, Saulo Fernandes; Fuentefria, Alexandre Meneghello

2017-10-01

Clioquinol is an 8-hydroxyquinoline derivative that was widely used from the 1950s to 1970s as an oral antiparasitic agent. In 1970, the oral forms were withdrawn from the market due to reports of toxicity, but topical formulations for antifungal treatment remained available. Thus, the purpose of this study was to evaluate the toxicity, anti-Candida and antidermatophyte activity and to determine pharmacodynamic characteristics of clioquinol and other 8-hydroxyquinoline derivatives (8-hydroxy-5-quinolinesulfonic acid and 8-hydroxy-7-iodo-5-quinolinesulfonic acid). Antifungal activity was tested by broth microdilution and the fungicidal or fungistatic effect was checked by a time-kill assay. Permeation and histopathological evaluation were performed in Franz diffusion cells with ear skin of pigs and examined under light microscopy. An HET-CAM test was used to determine the potential irritancy. The three compounds were active against all isolates showing anti-Candida and antidermatophyte activity, with MIC ranges of 0.031-2 μg/ml, 1-512 μg/ml, and 2-1024 μg/ml for clioquinol, 8-hydroxy-5-quinolinesulfonic acid, and 8-hydroxy-7-iodo-5-quinolinesulfonic acid, respectively. All compounds showed fungistatic effect for Candida, 8-hydroxy-5-quinolinesulfonic acid, and 8-hydroxy-7-iodo-5-quinolinesulfonic acid showed a fungicidal effect for M. canis and T. mentagrophytes, and clioquinol showed a fungicidal effect only for T. mentagrophytes. Furthermore, they presented a fungicidal effect depending on the time and concentration. The absence of lesions was observed in histopathological evaluation and no compound was irritating. Moreover, clioquinol and 8-hydroxy-5-quinolinesulfonic acid accumulated in the epithelial tissue, and 8-hydroxy-7-iodo-5-quinolinesulfonic acid had a high degree of permeation. In conclusion, 8-hydroxyquinoline derivatives showed antifungal activity and 8-hydroxy-5-quinolinesulfonic acid demonstrated the potential for antifungal drug design. © The Author 2017. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Electronic structure of the organic semiconductor Alq3 (aluminum tris-8-hydroxyquinoline) from soft x-ray spectroscopies and density functional theory calculations.

PubMed

DeMasi, A; Piper, L F J; Zhang, Y; Reid, I; Wang, S; Smith, K E; Downes, J E; Peltekis, N; McGuinness, C; Matsuura, A

2008-12-14

The element-specific electronic structure of the organic semiconductor aluminum tris-8-hydroxyquinoline (Alq(3)) has been studied using a combination of resonant x-ray emission spectroscopy, x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory (DFT) calculations. Resonant and nonresonant x-ray emission spectroscopy were used to measure directly the carbon, nitrogen and oxygen 2p partial densities of states in Alq(3), and good agreement was found with the results of DFT calculations. Furthermore, resonant x-ray emission at the carbon K-edge is shown to be able to measure the partial density of states associated with individual C sites. Finally, comparison of previous x-ray emission studies and the present data reveal the presence of clear photon-induced damage in the former.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 (Nd 3+), sodium (Na+), HDEHP, water, and lactate in the TALSPEAK liquid-liquid extraction system was explored under varied Nd 3+ 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 Nd 3+, Na +,more » lactate, and equilibrium pH were modeled using the SXLSQI software to obtain logKNd and logKNa extraction constants under selected conditions. Results showed that high Nd 3+ loading of the HDEHP led to Nd 3+ 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 (La 3+) for Nd 3+ 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 phase that becomes heterogeneous by the micellization of surfactants through the increase of temperature. To better understand the behavior of europium (Eu 3+) and 8-hydroxyquinoline under cloud point extraction conditions, potentiometric and spectrophotometric titrations coupled with modeling with Hyperquad and SQUAD computer programs were performed to assess europium (Eu 3+) and 8-hydroxyquinoline speciation. Experiments in both water and a 1wt% Triton X-114/water mixed solvent were compared to understand the effect of Triton X-114 on the system speciation. Results indicated that increased solvation of 8-hydroxyquinoline by the mixed solvent lead to more stable complexes involving 8-hydroxyquinoline than in water, whereas competition between hydroxide and Triton X-114 for Eu 3+ led to lower stability hydrolysis complexes in the mixed solvent than in water. Lanthanide speciation is challenging due to the trivalent oxidation state that leads to multiple ligand complexes, including some mixed complexes. The complexity of the system demands well-designed and precise experiments that capture the nuances of the chemistry. This work increased the understanding of lanthanide speciation in the explored systems, but more work is required to produce a comprehensive understanding of the speciation involved.« less

Coordination-supported organic polymers: mesoporous inorganic–organic materials with preferred stability

DOE PAGES

Chen, Dong; Zhang, Pengfei; Fang, Qianrong; ...

2018-01-01

A simple and versatile strategy is developed for the synthesis of coordination-supported organic polymers(COPs) via coordination between Al 3+ and 5-amino-8-hydroxyquinoline together with organic imine- or imide-based polycondensation.

Coordination-supported organic polymers: mesoporous inorganic–organic materials with preferred stability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Dong; Zhang, Pengfei; Fang, Qianrong

A simple and versatile strategy is developed for the synthesis of coordination-supported organic polymers(COPs) via coordination between Al 3+ and 5-amino-8-hydroxyquinoline together with organic imine- or imide-based polycondensation.

Electronic Structure of the Organic Semiconductor Alq3 (aluminum tris-8-hydroxyquinoline) from Soft X-ray Spectroscopies and Density Functional Theory Calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeMasi, A.; Piper, L; Zhang, Y

2008-01-01

The element-specific electronic structure of the organic semiconductor aluminum tris-8-hydroxyquinoline (Alq3) has been studied using a combination of resonant x-ray emission spectroscopy, x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory (DFT) calculations. Resonant and nonresonant x-ray emission spectroscopy were used to measure directly the carbon, nitrogen and oxygen 2p partial densities of states in Alq3, and good agreement was found with the results of DFT calculations. Furthermore, resonant x-ray emission at the carbon K-edge is shown to be able to measure the partial density of states associated with individual C sites. Finally, comparison of previous x-ray emission studiesmore » and the present data reveal the presence of clear photon-induced damage in the former.« less

Modulating the single-molecule magnet behaviour in phenoxo-O bridged Dy2 systems via subtle structural variations

NASA Astrophysics Data System (ADS)

Wang, Wen-Min; Zhao, Xiao-Yu; Qiao, Hui; Bai, Li; Han, Hong-Fei; Fang, Ming; Wu, Zhi-Lei; Zou, Ji-Yong

2017-09-01

In search of simple approaches to rationally modulate the single-molecule magnet behaviour in polynuclear lanthanide compound, a new system containing two structurally closely related dinuclear dysprosium complexes, namely [Dy2(hfac)4L2] (1) and [Dy2(hfac)4L‧2] (2) (hfac = hexafluoroacetylacetonate, HL = 2-[4-methylaniline-imino]methyl]-8-hydroxyquinoline and HL' = 2-[(3,4-dimethylaniline)-imino]methyl]-8-hydroxyquinoline), are successfully synthesized and the structure-dependent magnetic properties are investigated. The two Dy2 compounds display only slight variations in the coordination geometries of the center Dy(III) ion but display remarkably different single-molecule magnet behaviors with the anisotropic barriers (ΔE/kB) of 9.91 K for 1 and 20.57 K for 2. The different magnetic relaxation behaviors of the two Dy2 complexes mainly originate from the different chemical environments of the central DyIII ions.

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.

Surface Raman spectroscopy of the interface of tris-(8-hydroxyquinoline) aluminum with Mg.

PubMed

Davis, Robert J; Pemberton, Jeanne E

2009-07-29

Surface Raman spectroscopy in ultrahigh vacuum is used to interrogate interfaces formed between tris-(8-hydroxyquinoline) aluminum (Alq(3)) and vapor-deposited Mg. The Raman spectral results for deposition of Mg mass thicknesses between 5 and 20 A indicate formation of a complex interfacial region composed primarily of Mg-Alq(3) adducts and small-grained amorphous or nanocrystalline graphite, the presence of which may have a significant effect on the electronic properties of this metal-organic interface. The observed shifts in nu(ring), nu(C-N), nu(Al-N), and nu(Al-O) modes along with the appearance of nu(Mg-C) and nu(Mg-O) modes suggest a structure for the Mg-Alq(3) adduct in which Mg is bound to the O and C atoms of Alq(3). In addition, several intense, broad modes are observed that are consistent with partial graphitization of the Alq(3) film.

Analysis of molybdenum, tungsten, and vanadium in surface water of the Atlantic Ocean using solid phase extraction with 8-hydroxyquinoline and ICP MS determination

NASA Astrophysics Data System (ADS)

Rimskaya-Korsakova, M. N.; Berezhnaya, E. D.; Dubinin, A. V.

2017-07-01

An analytical technique is proposed to determine ultratrace concentrations of Mo, V, and W found in seawater using mass spectrometry with inductively coupled plasma (ICP MS) after preliminary concentration by solid-phase extraction of metal complexes with 8-hydroxyquinoline (8-HQ) on C18 octadecyl silica. The technique utilizes 150 mL of a water sample. A preconcentration factor 50 is obtained. The detection limits are 0.25 nmol/kg, 0.041 nmol/kg, and 5 pmol/kg for Mo, V, and W, respectively. Dissolved Mo, V, and Wconcentrations in surface seawater from Atlantic Ocean transect were determined. The concentrations ranges along the transect were: 91-108 nmol/kg for Mo, 28-35 nmol/kg for V, and 55-75 pmol/kg for W. The Mo/W ratio varied from 1300 to 1800.

Covalent Organic Framework Functionalized with 8-Hydroxyquinoline as a Dual-Mode Fluorescent and Colorimetric pH Sensor.

PubMed

Chen, Long; He, Linwei; Ma, Fuyin; Liu, Wei; Wang, Yaxing; Silver, Mark A; Chen, Lanhua; Zhu, Lin; Gui, Daxiang; Diwu, Juan; Chai, Zhifang; Wang, Shuao

2018-05-09

Real-time and accurate detection of pH in aqueous solution is of great significance in chemical, environmental, and engineering-related fields. We report here the use of 8-hydroxyquinoline-functionalized covalent organic framework (COF-HQ) for dual-mode pH sensing. In the fluorescent mode, the emission intensity of COF-HQ weakened as the pH decreased, and also displayed a good linear relationship against pH in the range from 1 to 5. In addition, COF-HQ showed discernible color changes from yellow to black as the acidity increased and can be therefore used as a colorimetric pH sensor. All these changes are reversible and COF-HQ can be recycled for multiple detection runs owing to its high hydrolytical stability. It can be further assembled into a mixed matrix membrane for practical applications.

Extraction of Pm(III) and Gd(III) by 8-hydroxyquinoline and some related amines in chloroform from nitrate medium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shehata, F.A.; Khalifa, S.M.; El-Dessouky, S.I.

1993-10-01

The extraction of the trivalent radioactive lanthanides (Ln), Pm and Gd from nitrate aqueous medium by 8-hydroxyquinoline (HOX) and/or trilaurylamine (TLA), trioctylamine (TOA), tributylamine (TBA), tripropylamine (TPA) or triallylamine (TAA),L, in chloroform was investigated. The chemical formulae of the extracted organic phase species for both lanthanides were found Ln.NO{sub 3}.(OX){sub 2} for the chelate and Ln.NO{sub 3}(OX){sub 2}.L for the adduct. The respective extraction and formation constants were evaluated. The synergic extraction of Pm and Gd by HOX-amine was investigated as a function of temperature. The thermodynamic parameters, free energy change, enthalpy change and entropy change were evaluated. The stoichiometrymore » of the extracted organic phase species was established and the different data obtained were discussed. 15 refs., 8 figs., 2 tabs.« less

8-Hydroxyquinolines Are Boosting Agents of Copper-Related Toxicity in Mycobacterium tuberculosis.

PubMed

Shah, Santosh; Dalecki, Alex G; Malalasekera, Aruni P; Crawford, Cameron L; Michalek, Suzanne M; Kutsch, Olaf; Sun, Jim; Bossmann, Stefan H; Wolschendorf, Frank

2016-10-01

Copper (Cu) ions are likely the most important immunological metal-related toxin utilized in controlling bacterial infections. Impairment of bacterial Cu resistance reduces viability within the host. Thus, pharmacological enhancement of Cu-mediated antibacterial toxicity may lead to novel strategies in drug discovery and development. Screening for Cu toxicity-enhancing antibacterial molecules identified 8-hydroxyquinoline (8HQ) to be a potent Cu-dependent bactericidal inhibitor of Mycobacterium tuberculosis The MIC of 8HQ in the presence of Cu was 0.16 μM for replicating and nonreplicating M. tuberculosis cells. We found 8HQ's activity to be dependent on the presence of extracellular Cu and to be related to an increase in cell-associated labile Cu ions. Both findings are consistent with 8HQ acting as a Cu ionophore. Accordingly, we identified the 1:1 complex of 8HQ and Cu to be its active form, with Zn, Fe, or Mn neither enhancing nor reducing its Cu-specific action. This is remarkable, considering that the respective metal complexes have nearly identical structures and geometries. Finally, we found 8HQ to kill M. tuberculosis selectively within infected primary macrophages. Given the stark Cu-dependent nature of 8HQ activity, this is the first piece of evidence that Cu ions within macrophages may bestow antibacterial properties to a Cu-dependent inhibitor of M. tuberculosis In conclusion, our findings highlight the metal-binding ability of the 8-hydroxyquinoline scaffold to be a potential focus for future medicinal chemistry and highlight the potential of innate immunity-inspired screening platforms to reveal molecules with novel modes of action against M. tuberculosis. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Hydrogen bond assisted interaction of glutamine with chromium (III) complex of 8-hydroxyquinoline: Experimental and theoretical studies

NASA Astrophysics Data System (ADS)

Narayanan, Jayanthi; Carlos-Alberto, Aguilar H.; Arturo, Lazarini M.; Höpfl, Herbert; Enrique-Fernando, Velazquez C.; Fernando, Rocha A.; Fernando-Toyohiko, Wakida K.; Velazquez-Lopez, José E.; Lesli, Arroyo O.

2018-03-01

Chromium (III) complex [Cr (hq)3;C2H5OH] of 8-hydroxyquinoline (hq) was prepared and its structure was resolved by X-ray diffraction analysis at low-temperature, showing that Cr3+ ion presents in distorted octahedral geometry, and it is consistent with the DFT optimized structure. It was observed that solvent ethanol is involved a hydrogen bond with 8-hydroxyquinoline anion. Furthermore, the molecular orbital contributions to spectral bands observed for the complex were determined by TD-DFT. The interaction of [Cr (hq)3;C2H5OH] with glutamine (Gln) or asparagine (Asn) shows that the complex binds effectively with glutamine through hydrogen bonding (H2N+-HṡṡṡOethanol) to form a possible stable adduct [Cr (hq)3;C2H5OH)Gln], yielding its binding constant 10,000 times greater (1.4315 M-1) than that for Asn (5.0 × 10-4 M-1). This is apparently due to the formation of stable secondary coordination sphere through the hydrogen bond between the metal complex with Gln. This observation is good agreement with the total molecular energy as well as with the molecular orbital study, i.e. in the DFT calculation, a lower total molecular energy (-8299,549.441 kcal/mmol) for [Cr (hq)3;C2H5OH) Gln] was obtained than that resulted for [Cr (hq)3;C2H5OH)Asn] (-8194,799.867 kcal/mmol), establishing ethanol effectively stabilizes the interaction between glutamine and the complex. Finally, antibacterial properties of [Cr (hq)3;C2H5OH] against Gram positive Bacillus cereus and Gram negative Escherichia coli was also studied, and compared its bacterial growths for its adducts of glutamine or of asparagine.

Nanowires of metal (Cd, Cu) halide complexes with 8-hydroxyquinoline for photoelectrochemical and electrochemiluminescence sensing

NASA Astrophysics Data System (ADS)

Huang, Shan; Pang, Guangming; Li, Xiangkui; Li, Jianping; Pan, Hongcheng

2017-12-01

Metal-hydroxyquinoline-halogen (MqX, M = Cd, Cu; q = 8-hydroxyquinoline; X = Cl, Br, I) nanowires are synthesized via a sonochemical-assisted method. The elemental analysis (EA), inductively coupled plasma-optical emission spectroscopy (ICP-AES), and X-ray photoelectron spectroscopy (XPS) support an M/q/X ratio of 1:1:1. The electron microscope images reveal a typical CdqX and CuqX nanowire diameter of 30-50 nm and a nanowire length of 400-600 nm. In addition, the synthesis of the MqX nanowires is only observed when there is an excess of halide ions (X/q molar ratio of 3 or greater). This halide deficiency results in the formation of micrometer-sized Mq2 sheets. We demonstrated the conversion of the MqX nanowires to Mq2 micro-sheets in an ultrasonic bath of 1 M 8-Hq ethanol solutions (50%, w/ w) at 50 °C for 2 h, but not vice versa. The MqX nanowires exhibited excellent properties for photoluminescence, electrochemiluminescence (ECL), and photoelectrochemistry (PEC). The CdqBr and CdqI nanowires were coated onto a glass carbon and a fluorine-doped tin oxide glass electrode to develop the above ECL and PEC methods for the detection of H2O2 and Cu2+, respectively. In the range of 2 to 14 μM, the ECL intensity of the CdqBr nanowires was inversely proportional to the concentration of H2O2 with a detection limit of 0.26 μM. For Cu2+ sensing, the photocurrent of the CdqI nanowires exhibited a linear response to Cu2+ over the range of 2 to 16 μM of which a detection limit of 0.2 μM was observed.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, Min; Xiao, Teng; Liu, Rui

2011-10-11

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

Write once read many memory device from Tris-8 (-hydroxyquinoline) aluminum and Indium tin oxide nano particles

NASA Astrophysics Data System (ADS)

Aneesh, J.; Predeep, P.

2011-10-01

Consequent to the fast increase in data storage requirements new materials and device structures are explored in a war footing. Organic memory devices are attracting lot of interest among the researchers and are becoming a hot topic of investigations. This study is an attempt to develop a tri-layer organic memory device using indium tin oxide (ITO) nanoparticles as charge trapping middle layer between tris-8(-hydroxyquinoline)aluminum (Alq3) layers employing spin coating technique. Device switching is studied by applying a current-voltage (I-V) sweep. On increasing the applied bias the device switched from the initial high resistance (OFF) state to a low resistance (ON) state at a switch on voltage of around 4 V. ON/OFF ratio is of the order of 100 at a read voltage of 2 V. The device is found to remain in the low resistance state on further scans, showing the applicability of this device as a write once read many times (WORM) memory.

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

PubMed

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). Copyright © 2013 Elsevier B.V. All rights reserved.

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).

Generation and decay dynamics of triplet excitons in Alq3 thin films under high-density excitation conditions.

PubMed

Watanabe, Sadayuki; Furube, Akihiro; Katoh, Ryuzi

2006-08-31

We studied the generation and decay dynamics of triplet excitons in tris-(8-hydroxyquinoline) aluminum (Alq3) thin films by using transient absorption spectroscopy. Absorption spectra of both singlet and triplet excitons in the film were identified by comparison with transient absorption spectra of the ligand molecule (8-hydroxyquinoline) itself and the excited triplet state in solution previously reported. By measuring the excitation light intensity dependence of the absorption, we found that exciton annihilation dominated under high-density excitation conditions. Annihilation rate constants were estimated to be gammaSS = (6 +/- 3) x 10(-11) cm3 s(-1) for single excitons and gammaTT = (4 +/- 2) x 10(-13) cm3 s(-1) for triplet excitons. From detailed analysis of the light intensity dependence of the quantum yield of triplet excitons under high-density conditions, triplet excitons were mainly generated through fission from highly excited singlet states populated by singlet-singlet exciton annihilation. We estimated that 30% of the highly excited states underwent fission.

Luminance mechanisms in green organic light-emitting devices fabricated utilizing tris(8-hydroxyquinoline)aluminum/4,7-diphenyl-1, 10-phenanthroline multiple heterostructures acting as an electron transport layer.

PubMed

Choo, Dong Chul; Seo, Su Yul; Kim, Tae Whan; Jin, You Young; Seo, Ji Hyun; Kim, Young Kwan

2010-05-01

The electrical and the optical properties in green organic light-emitting devices (OLEDs) fabricated utilizing tris(8-hydroxyquinoline)aluminum (Alq3)/4,7-diphenyl-1,10-phenanthroline (BPhen) multiple heterostructures acting as an electron transport layer (ETL) were investigated. The operating voltage of the OLEDs with a multiple heterostructure ETL increased with increasing the number of the Alq3/BPhen heterostructures because more electrons were accumulated at the Alq3/BPhen heterointerfaces. The number of the leakage holes existing in the multiple heterostructure ETL of the OLEDs at a low voltage range slightly increased due to an increase of the internal electric field generated from the accumulated electrons at the Alq3/BPhen heterointerface. The luminance efficiency of the OLEDs with a multiple heterostructure ETL at a high voltage range became stabilized because the increase of the number of the heterointerface decreased the quantity of electrons accumulated at each heterointerface.

Photoluminescence of Alq3 - and Tb-activated aluminium-tris(8-hydroxyquinoline) complex for blue chip-excited OLEDs.

PubMed

Yawalkar, P W; Dhoble, S J; Thejo Kalyani, N; Atram, R G; Kokode, N S

2013-01-01

The tris(8-hydroxyquinoline)-aluminium complex is the most important and widely studied as electron transporting and green light emitting material. Alq(3) and Tb(x) Al((1-x)) q(3) have been synthesized (where x = 0.1, 0.3, 0.5, 0.7 and 0.9) and blended films of Alq(3) and Tb(x) Al((1-x)) q(3) with PMMA and PS at different percentage weight (wt%) concentrations (e.g., 0.1, 1, 5, 10, 25 and 50 wt%) have been prepared. The synthesized materials and their blended thin films have been characterized by a photoluminescence (PL) technique; the synthesis and PL characterization are reported in this paper. The synthesized metal complex shows bright emission of green light with blue light excitation (440 nm) and the prepared Tb(x) Al((1-x)) q(3) phosphor may be applicable in blue chip-excited OLEDs for the newly developed wallpaper lighting technology. Copyright © 2012 John Wiley & Sons, Ltd.

Spectral and time-resolved properties of photoinduced hydroxyquinolines doped thin polymer films

NASA Astrophysics Data System (ADS)

Mehata, Mohan Singh

2018-01-01

Quinoline and its derivatives have a wide range of biological and pharmacological activities. Quinoline ring is used to design functional materials (quinoline derivatives) for OLEDs and field-induce electrooptics. It possesses antibacterial, antifungal, antimalarial, cardiotonic, anthelmintic, anti-inflammatory, anticonvulsant and analgesic activity. Here, we have examined photoexcitation dynamics of 6-hydroxyquinoline (6-HQ) doped in polymer films of polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA) and cellulose acetate (CA) at atmospheric conditions. The absorption maximum of 6-HQ in polymer films was observed at 333 ± 1 nm, whereas fluorescence (FL) maximum fell in the range of 365-371 nm. In PVA film, in addition to the typical FL, a band maximum at 432 nm appeared as a result of an excited-state intermolecular proton transfer (ESIPT) reaction facilitated in the hydrogen-bonded complex formed in the ground state between 6-HQ:PVA. The multi-exponential decay behavior of 6-HQ in all the three polymer films indicates a nanoscale heterogeneity of the polymer environments.

Synthesis, structural elucidation, solvatochromism and spectroscopic properties of some azo dyes derived from 6-chloro-4-hydroxyquinoline-2(1H)-one

NASA Astrophysics Data System (ADS)

Rufchahi, E. O. Moradi; Gilani, A. Ghanadzadeh; Taghvaei, V.; Karimi, R.; Ramezanzade, N.

2016-03-01

Malondianilide (I) derived from p-chloroaniline was cyclized to 6-chloro-4-hydroxyquinoline-2(1H)-one (II) in moderately good yield using polyphosphoric acid as catalyst. This compound was then coupled with some diazotized aromatic amines to give the corresponding azo disperse dyes 1-12. A systematic study of the effect of solvent, acid, base and pH upon the electronic absorption spectra of the dyes 1-12 was carried out. In DMSO, DMF, CH3CN, CHCl3, EtOH and acidic media (CH3COOH, acidified EtOH) these dyes that theoretically may be involved in azo-hydrazone tautomerism have been detected only as hydrazone tautomers T1 and T2. The acidic dissociation constants of the dyes were measured in 80 vol% ethanol-water solution at room temperature and ionic strength of 0.1. The results were correlated by the Hammett-type equation using the substituent constants σx.

Kinetics of the substitution of dehydroacetic acid in tris (dehydroacetato) Fe(III) complex by 8-hydroxyquinoline, di- and tetra-hydroxyquinone

NASA Astrophysics Data System (ADS)

Fouad, D. M.; Ismail, N. M.; El-Gahami, M. A.; Ibrahim, S. A.

2007-06-01

The ligand substitution reactions of dehydroacetic acid (Hdha) in [Fe(dha) 3] with second ligand such as 8-hydroxyquinoline (Hquin), 1,4-dihydroxyanthraquinone (H 2dhaq) and 1,4,5,8-tetra-hydroxyanthraquinone (H 4thaq) were investigated spectrophotometrically by in low polarity solvents like benzene, chloroform and dichloromethane. It is deduced that the substitution reaction takes place through one successive step. The reaction was performed at four different temperatures (5-25) °C, and it exhibits a first order dependence on the concentration of the starting complex. The observed rate constant depends on the concentration of both leaving and entering ligands. The evaluation of the kinetic data gives activation parameters which support an associative mechanism in the transition states and the higher rate of substitution of the dha in Fe(dha) 3 complex is due to entropy effect. The solid complexes were synthesized and characterized by elemental analysis, IR and UV-vis spectral techniques.

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...

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…

Efficient Molecular Organic Light-Emitting Diodes Based on Silole Derivatives

DTIC Science & Technology

2003-01-01

TPD) and tris-(8-hydroxyquinoline) aluminum ( Alq3 ), commonly used in MOLEDs, have hole and electron mobilities that differ by a factor of ~1000 (~10...and subsequent device degradation. In addition to the widely used electron transporter Alq3 , [8] derivatives of nathrolines, [7] oxadiazoles, [9

Discovery of covalent inhibitors for MIF tautomerase via cocrystal structures with phantom hits from virtual screening

DOE Office of Scientific and Technical Information (OSTI.GOV)

McLean, Larry R.; Zhang, Ying; Li, Hua

Biochemical and X-ray crystallographic studies confirmed that hydroxyquinoline derivatives identified by virtual screening were actually covalent inhibitors of the MIF tautomerase. Adducts were formed by N-alkylation of the Pro-1 at the catalytic site with a loss of an amino group of the inhibitor.

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.

Plutonium Extraction by the Formation of Insoluble Salts; EXTRACTION DU PLUTONIUM PAR FORMATION DE SELS INSOLUBLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ganivet, M.

1960-06-29

The aim of this work is to convert Pu IV nitrate in solution into an insoluble salt. Three methods have been studied: 1) the conventional oxalic acid method was improved; 2) precipitation with 8-hydroxyquinoline was tried; 3) the hydrogen peroxide method was adapted to the eluates of the ionic resins from Marcoule. The yield from the oxalic process has been increased (loss of Pu in the mother-liquor brought from 200 mg/l to 20 mg/l). The study of Pu IV precipitation by 8-hydroxyquinoline has shown that the yield is excellent (Pu concentration in the mother-liquor less than 5 mg/h), but decontaminationmore » from impurities is nil. Finally, experiments on the precipitation by hydrogen peroxide of Pu IV solutions at the concentrations normally obtained from the anionic resins at Marcoule have given us good yields (Pu concentration in the mother-liquor less than 7 mg/l), and the purification is better than that obtained by oxalic acid (1000 ppm total impurities after a precipitation). (author)« less

Preconcentration of Zr, Hf, Nb, Ta and W in seawater using solid-phase extraction on TSK-8-hydroxyquinoline resin and determination by inductively coupled plasma-mass spectrometry.

PubMed

Firdaus, M Lutfi; Norisuye, Kazuhiro; Sato, Taishi; Urushihara, Shouhei; Nakagawa, Yusuke; Umetani, Shigeo; Sohrin, Yoshiki

2007-02-05

Here, we present the first simultaneous preconcentration and determination of ultratrace (pmol kg(-1) level) Zr, Hf, Nb, Ta and W in seawater, both in the form of dissolved and acid-dissolvable species. 8-Hydroxyquinoline (8HQ) bonded covalently to a vinyl polymer resin, TSK-8HQ, was used in a chelating adsorbent column to concentrate the metals. The greatest advantage of this resin is its endurance to 5M HF, since this is an effective eluent for all five metals. The analytes were successfully concentrated from 250 mL seawater with a 50-fold concentration factor through the column extraction and evaporation. The detection limit was 0.009-0.15 pmol kg(-1). The procedure blank determined using ultra pure water as a sample was 0.005-0.37 pmol kg(-1). The five metals were quantitatively recovered from seawater with good precision (2-4%). The effect of sample pH, sample flow rate, eluent composition and sample pretreatment were carefully studied. This method was applied to seawater.

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.

Improvement of amplified spontaneous emission performance by doping tris(8-hydroxyquinoline) aluminum (Alq3) in dye-doped polymer thin films.

PubMed

Lu, Wu; You, Han; Fang, Junfeng; Ma, Dongge

2007-04-20

A well-known red fluorescent dye 4-(dicy-anomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) was codoped with an electron transport organic molecule tris(8-hydroxyquinoline) aluminum (Alq(3)) in a host matrix of polystyrene (PS), and the amplified spontaneous emission (ASE) was studied by optically pumping. It was found that the ASE performance was significantly improved by the introduction of Alq(3). The Alq(3):DCJTB:PS blending thin films showed a low threshold (2.4 microJ/pulse) and a high net gain coefficient (109.95 cm(-1)) compared with the pure DCJTB:PS system (threshold of 15.2 microJ/pulse and gain of 35.94 cm(-1)). The improvement of the ASE performance was considered to be attributable to the effective Föster energy transfer from Alq(3) to DCJTB. Our results demonstrate that the Alq(3):DCJTB could be a promising candidate as gain medium for red organic diode lasers.

Spinterface between tris(8-hydroxyquinoline)metal(III) molecules and magnetic surfaces: a first-principles study

NASA Astrophysics Data System (ADS)

Jiang, W.; Wang, Jingying; Dougherty, Daniel; Liu, Feng; Feng Liu Team; Daniel Dougherty Team

Using first-principles calculations, we have systematically investigated the hybridization between tris(8-hydroxyquinoline)metal(III) (Mq3, M = Fe, Cr, Al) molecules and magnetic substrates (Co and Cr). Mq3 with different central metal elements but the same organic framework has dramatically different interaction with different magnetic substrates, which affect the interface state significantly. AFM coupling was observed between magnetic Mq3 molecules and ferromagnetic (Co) as well as antiferromagnetic (Cr) substrate, manifested with a superexchange and direct exchange interaction, respectively. Such strong magnetic interfacial coupling may open a gap around the Fermi level and significantly change interface transport properties. Nonmagnetic Alq3 molecule was found to enhance the interface spin polarization due to hybridization between the lowest unoccupied molecular orbitals (LUMO) of Alq3 and metallic surface state. These findings will help better understand spinterface and shed new light on future application of Mq3 molecules in spintronics devices. This work was support by NSF-MRSEC (DMR-1121252) and DOE-BES (DE-FG02-04ER46148).

Synthesis, Characterization, and Antibacterial Studies of Mixed Ligand Dioxouranium Complexes with 8-Hydroxyquinoline and Some Amino Acids

PubMed Central

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

2011-01-01

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 amino acids (HL) such as L-threonine, L-tryptophan, and L-isoleucine as secondary ligands. The metal complexes have been characterized by elemental analysis, electrical conductance, magnetic susceptibility measurements, and spectral and thermal studies. The electrical conductance studies of the complexes indicate their nonelectrolytic nature. Magnetic susceptibility measurements revealed diamagnetic nature of the complexes. Electronic absorption spectra of the complexes show intraligand 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 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. diphtheriae, S. typhi, and E. coli. PMID:22389843

Evolution from a natural flavones nucleus to obtain 2-(4-Propoxyphenyl)quinoline derivatives as potent inhibitors of the S. aureus NorA efflux pump.

PubMed

Sabatini, Stefano; Gosetto, Francesca; Manfroni, Giuseppe; Tabarrini, Oriana; Kaatz, Glenn W; Patel, Diixa; Cecchetti, Violetta

2011-08-25

Overexpression of efflux pumps is an important mechanism by which bacteria evade the effects of substrate antimicrobial agents. Inhibition of such pumps is a promising strategy to circumvent this resistance mechanism. NorA is a Staphylococcus aureus efflux pump that confers reduced susceptibility to many structurally unrelated agents, including fluoroquinolones, resulting in a multidrug resistant phenotype. In this work, a series of 2-phenyl-4(1H)-quinolone and 2-phenyl-4-hydroxyquinoline derivatives, obtained by modifying the flavone nucleus of known efflux pump inhibitors (EPIs), were synthesized in an effort to identify more potent S. aureus NorA EPIs. The 2-phenyl-4-hydroxyquinoline derivatives 28f and 29f display potent EPI activity against SA-1199B, a strain that overexpresses norA, in an ethidium bromide efflux inhibition assay. The same compounds, in combination with ciprofloxacin, were able to completely restore its antibacterial activity against both S. aureus SA-K2378 and SA-1199B, norA-overexpressing strains. © 2011 American Chemical Society

Self-assembly of five 8-hydroxyquinolinate-based complexes: tunable core, supramolecular structure, and photoluminescence properties.

PubMed

Yuan, Guozan; Shan, Weilong; Qiao, Xuelong; Ma, Li; Huo, Yanping

2014-07-01

Five new Zn(II) complexes, namely [Zn(3)(L)(6)] (1), [Zn(2)(Cl)(2)(L)(2) (py)(2)] (2), [Zn(2)(Br)(2) (L)(2)(py)(2)] (3), [Zn(L)(2)(py)] (4), and [Zn(2)(OAc)(2)(L)(2)(py)(2)] (5), were prepared by the solvothermal reaction of ZnX(2) (X(-) =Cl(-), Br(-), F(-), and OAc(-)) salts with a 8-hydroxyquinolinate ligand (HL) that contained a trifluorophenyl group. All of the complexes were characterized by elemental analysis, IR spectroscopy, and powder and single-crystal X-ray crystallography. The building blocks exhibited unprecedented structural diversification and their self-assembly afforded one mononuclear, three binuclear, and one trinuclear Zn(II) structures in response to different anions and solvent systems. Complexes 1-5 featured four types of supramolecular network controlled by non-covalent interactions, such as π⋅⋅⋅π-stacking, C-H⋅⋅⋅π, hydrogen-bonding, and halogen-related interactions. Investigation of their photoluminescence properties exhibited disparate emission wavelengths, lifetimes, and quantum yields in the solid state. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Anticlostridial agent 8-hydroxyquinoline improves the isolation of faecal bifidobacteria on modified Wilkins-Chalgren agar with mupirocin.

PubMed

Novakova, J; Vlkova, E; Salmonova, H; Pechar, R; Rada, V; Kokoska, L

2016-04-01

The need for suitable selective cultivation media for the isolation of Bifidobacterium spp. continues to be a real concern in the field of intestinal microbiology. Isolation of bifidobacteria from human and animal faecal samples using selective agar plating may be problematic especially in samples with increased clostridial counts than bifidobacterial counts. Due to the absence of anticlostridial agents in existing selective media, clostridia can displace bifidobacteria resulting in incorrect estimation of their counts. Therefore, we supplemented the existing selective medium 'modified Wilkins Chalgren agar with mupirocin' (MWM) with 90 mg l(-1) of 8-hydroxyquinoline (8HQ), which was recently proved to act selectively against clostridia. The newly composed 'modified Wilkins-Chalgren agar with 8HQ' (MWMQ) was tested on pure bifidobacterial and clostridial strains, their mixtures, and using faecal samples of mammalian origin; its selectivity was evaluated by genus-specific identification of isolates. The results demonstrated that the presence of 8HQ in this agar eliminated the growth of nonbifidobacterial strains on MWMQ compared to that on MWM, whereas the recovery of bifidobacterial counts was at satisfactory levels. In conclusion, MWMQ could be recommended for bifidobacterial isolation from human and animal faeces especially when bifidobacteria are not numerically dominant and there are chances of clostridial contamination. Routine isolation of bifidobacteria from mammalian faeces does not use a reliable selective agar with an anticlostridial agent. Overgrowth of clostridia may result in incorrect estimation of bifidobacterial counts. Thus, in order to improve the selectivity of existing media for bifidobacterial isolation, we chose the modified Wilkins-Chalgren agar with mupirocin and supplemented it with 8-hydroxyquinoline (8HQ), a molecule that shows anticlostridial activity without affecting the growth of bifidobacteria. This newly composed medium showed enhanced selectivity and specificity compared to the original medium and therefore, can be recommended for the isolation of bifidobacteria from mammal faeces. © 2016 The Society for Applied Microbiology.

Multifunctional (3-in-1) cancer theranostics applications of hydroxyquinoline-appended polyfluorene nanoparticles† †Electronic supplementary information (ESI) available: Synthesis, characterization, stability, optical properties, imaging, drug delivery, etc. See DOI: 10.1039/c7sc03321d

PubMed Central

Chowdhury, Sayan Roy; Mukherjee, Sudip; Das, Sourav

2017-01-01

The accumulation of fluorescent hydroxyquinoline-affixed polyfluorene (PF-HQ) nanoparticles and their utility for multi-color bio-imaging and drug delivery for cancer treatment are reported. The formation of nanoparticles (PF-HQ) containing hydrophobic pockets via three-dimensional growth of a polymeric backbone in a higher water fraction (THF : H2O = 1 : 9) was observed. The nanoparticles showed incredible dual-state optical and fluorescence properties, which were further explored in multi-color cell imaging in both cancer and normal cells. The cell viability assay in various normal cells confirmed the biocompatible nature of PF-HQ, which was further supported by an ex vivo (chick chorioallantoic membrane assay) model. This encouraged us to fabricate PF-HQ-based new drug delivery systems (DDS: PF-HQ–DOX) upon conjugation with the FDA-approved anti-cancer drug doxorubicin (DOX) by filling the hydrophobic pockets of the polymer nanoparticles. The enhanced anti-cancer activity of the DDS (PF-HQ–DOX) compared with that of free DOX was observed in mouse melanoma cancer cells (B16F10) and a subcutaneous mouse (C57BL6/J) melanoma tumor model upon administration of PF-HQ–DOX. Ex vivo biodistribution studies using a fluorescence quantification method demonstrated the enhanced accumulation of DOX in tumor tissues in the PF-HQ–DOX-treated group compared to that of the free drug, signifying the drug delivery efficacy of the delivery system by a passive targeting manner. Based on the above biological data (in vitro and in the pre-clinical model), these robust and versatile fluorescent hydroxyquinoline-affixed polyfluorene (PF-HQ) nanoparticles could be effectively utilized for multifunctional biomedical applications (as they are biocompatible and can be used for bio-imaging and as a drug delivery vehicle). PMID:29568419

Characterization of Alq3 thin films by a near-field microwave microprobe.

PubMed

Hovsepyan, Artur; Lee, Huneung; Sargsyan, Tigran; Melikyan, Harutyun; Yoon, Youngwoon; Babajanyan, Arsen; Friedman, Barry; Lee, Kiejin

2008-09-01

We observed tris-8-hydroxyquinoline aluminum (Alq3) thin films dependence on substrate heating temperatures by using a near-field microwave microprobe (NFMM) and by optical absorption at wavelengths between 200 and 900 nm. The changes of absorption intensity at different substrate heating temperatures are correlated to the changes in the sheet resistance of Alq3 thin films.

Facile solution synthesis of hexagonal Alq3 nanorods and their field emission properties.

PubMed

Hu, Jin-Song; Ji, Heng-Xing; Cao, An-Min; Huang, Zheng-Xi; Zhang, Yang; Wan, Li-Jun; Xia, An-Dong; Yu, Da-Peng; Meng, Xiang-Min; Lee, Shuit-Tong

2007-08-07

A facile self-assembly growth route assisted by surfactant has been developed to synthesize tris(8-hydroxyquinoline)aluminium (Alq(3)) nanorods with regular hexagonal shape and good crystallinity, which exhibit field-emission characteristics with a very low turn-on field of ca. 3.1 V microm(-1) and a high field-enhancement factor of ca. 1300.

An artificial guanine that binds cytidine through the cooperative interaction of metal coordination and hydrogen bonding.

PubMed

Mancin, Fabrizio; Chin, Jik

2002-09-18

Cd(II) complex of L binds selectively to cytidine in DMSO with an equilibrium constant of 117 M-1 (where LH is 2-aminomethyl-8-hydroxyquinoline). In contrast, the Zn(II) complex of L does not bind appreciably to any of the four nucleobases under the same condition used for the Cd(II) complex.

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...

Intermolecular interactions in the solid state structures of neutral and N-protonated 5-alkoxymethyl-8-hydroxyquinolines

NASA Astrophysics Data System (ADS)

Schulze, Mathias M.; Böhme, Uwe; Schwarzer, Anke; Weber, Edwin

2017-04-01

A series of five different alkoxymethyl substituted derivatives of 8-hydroxyquinoline was synthesised both in protonated (1a-1e) and neutral (2a-2e) form. The alkoxymethyl groups are MeO (1a, 2a), EtO (1b, 2b), n-PrO (1c, 2c), iso-PrO (1d, 2d), n-BuO (1e, 2e). The compounds were characterised by single crystal X-ray diffraction and spectroscopic methods. Hirshfeld surface analysis was performed to analyse the crystal packing quantitatively. Topological analysis of the electron density distribution delivers information about the strength of the hydrogen bonds. The overall results reveal a main difference between the charged (1a-1d) and uncharged (2a-2e) compounds in the orientation of the hydroxyl group resulting in a different cyclic dimer formation. In both cases the structures are dominated by hydrogen bonding (1a-1d: Osbnd H⋯Cl, Nsbnd H⋯Cl and 2a-2e: Osbnd H⋯N). Furthermore, all crystal structures show π involved interactions though taking only a minor part in the packing of the molecules.

"CH"/N substituted mer-Gaq3 and mer-Alq3 derivatives: an effective approach for the tuning of emitting color.

PubMed

Gahungu, Godefroid; Zhang, Jingping

2005-09-22

Equilibrium geometry configurations of the "CH"/N substituted Alq3 and Gaq3 derivatives are calculated by density functional theory (B3LYP/6-31G). The frontier molecular orbital and gap energy calculations for all complexes have been performed at the HF/6-31G level. It was shown that, compared to the pristine molecules, the HOMO and LUMO are stabilized, the net effect being however an increasing/decreasing of the gap (Eg) depending on the position of the substituted group. On the basis of the equilibrium geometries, the effect of the substitution on the absorption and emission spectra was evaluated using TDB3LYP/3-21G. It was shown that the change of "CH"/N substituted position on 8-hydroxyquinoline ligand is a powerful approach for the tuning of emitting color. An important blue shift was predicted for 5-substituted 8-hydroxyquinoline derivatives, an important red one being observed for 4-substituted ones. Interestingly, relatively significant blue and red shifts were also predicted for the 7- and 2-substituted derivatives. In this work, the correlation between the spectrum shifts and the metal-ligand bonding is also discussed.

Speciation of aluminum in drink samples by 8-hydroxyquinoline loaded silylanization silica gel microcolumn separation with off-line ICP-MS detection.

PubMed

Chen, Jie; Huang, Chaozhang; Hu, Bin; Jiang, Zucheng

2004-11-17

A technique using a flow injection microcolumn separation coupled with ICP-MS detection has been developed for the speciation of Al in drink samples. The retention behaviors of different Al species were studied with 8-hydroxyquinoline (8-HQ) loaded silylanization silica gel as the packing material and inorganic acid (HNO3) as the elution. The results indicated that in a pH range of 5.0 to 8.0, all labile monomeric Al species were retained on the microcolumn while nonlabile monomeric Al species were directly passed through the column. Various Al species after separation were detected by ICP-MS. The detection limit of 0.2 ng mL(-1) and a relative standard deviation (RSD) of 4.2% at 10 ng mL(-1) (n = 11) were achieved, and the recoveries for the spiked samples were 95-108%. The proposed method has been applied to the analysis of Al species in tea infusions, coffee, and tap waters with satisfactory results. The results obtained by this method were compared with that obtained by the cation exchange microcolumn separation and ICP-MS detection system, and some valuable conclusions were drawn.

Experimental and theoretical studies of structural and photophysical properties of a novel heteroleptic cyclometalated iridium(III) complex with 8-hydroxyquinoline-phenylazo ligand

NASA Astrophysics Data System (ADS)

Maity, Amit; Sinha, Debopam; Rajak, Kajal Krishna

2018-04-01

One novel heteroleptic iridium(III) complex with cyclometalated 2-phenylquinoline(2-phq) was synthesized by the stoichiometric reaction of [Ir(2-phq)2Cl]2, i.e, Bis-[μ-chlorodi-(2-phenylquinoline)iridium(III)] and HL ligand, where L- is deprotonated form of azo ligand prepared from 8-hydroxyquinoline and aniline in a 1:1 proportion of dichloromethane and ethanol solvent at argon atmosphere in presence of mild base triethylamine in stoichiometric ratio. The prepared complex was characterized by 1H NMR, ESI-mass spectrometry, IR spectroscopy and most accurately by X-ray single crystallography. The photo physical properties like absorption and emission, i.e, photoluminescence in liquid state as well as solid state were studied exclusively. The experimental electrochemical study was also done with cyclic voltammetry. The theoretical investigations of the photo physical properties were done by DFT and TDDFT calculations. The ground state excitation transitions of the complex arise from 1ILCT and 1MLCT transition. The UV-Vis and photoluminescence transition was also investigated by NTO analysis. The triplet state emission transition was characterized by 3MLCT and some portion of 3ILCT transition.

Iron chelating ligand for iron overload diseases.

PubMed

Ozbolat, G; Tuli, A

2018-01-01

Iron overloads are a serious clinical condition in the health of humans and are therefore a key target in drug development. In this study, iron(III) complex of 8-hydroxyquinoline-5 sulphonic acid was synthesized and structurally characterized in its solid state and solution state by FT-IR, UV-Vis, elemental analysis, magnetic susceptibility and 1H-NMR. The catalase activities of complex were investigated. It was showed that the complex has the catalase activity. It is suggested that this type of complex may constitute a new and interesting basis for the future search for new and more potential drugs. The electrochemical behaviour patterns of the ligand and complex were examined as supporting electrolyte and platinum electrode for cyclic voltammetry. The electrochemistry studies showed that the reductions in free ligand and complex take place differently.The cytotoxicity was evaluated by MTT assay. The complex exhibited a very high cytotoxic activity and showed a cytotoxic effect that was much better than that of the ligand.The observed cytotoxicity could be pursued to obtain a potential drug. These results indicate that using the 8-hydroxyquinoline-5 sulphonic acid for this aim in further studies is appropriate (Tab. 1, Fig. 4, Ref. 18). Text in PDF www.elis.sk.

Photosynthetic Complexes: Molecularly Activated Bioswitches and Agents for Light Powered Molecular Circuitry

DTIC Science & Technology

2004-09-11

we can alter its mechanical interactions with 5.OeV: , Alq3 5.0eV’ ETL BCP polar or charged samples by, for example, aligning polar -P700-: ,p...tris(8-hydroxyquinoline) aluminum, 0.4Alq3-.21 Alq3 is transparent at the characteristic A = 680 nm a absorption peak of PSI. Alq 3 is also a

Permeation Studies of CW Agents with Fabric Treated with 8-Hydroxyquinoline

DTIC Science & Technology

2017-12-01

Jeffery R. Owens AIR FORCE CIVIL ENGINEER CENTER AFCEC/CXAE, Tyndall AFB, FL 32403-5320 December 2017 Approved for public release: distribution...P.O. Box 68, Gunpowder, MD 21010-0068 Universal Technology Corp.; 139 Barnes Drive Suite 2 Tyndall AFB, FL 32404-5325 Air Force Civil Engineer ...moisture transport. The garment prevents exposure to outside chemical weapons agents (CWAs) by reacting or reducing permeation of the CWA. By

Maskless Nanoscale Writing of Nanoparticle-Polymer Composites and Nanoparticle Assemblies using Thermal Nanoprobes

DTIC Science & Technology

2009-09-14

the otherwise difficult to deposit Alq3 using a p(VDF-TrFE) carrier. The Alq3 retains its ability to fluoresce after deposition. (h) SEM of the...aluminum tris(8-hydroxyquinoline) ( Alq3 ) ∼0.9 P(VDF-TrFE) 1 zinc diethyldithiocarbamate ∼1.2 P(VDF-TrFE) 1 CdSe-ZnS core-shell 2-4 PE 1 dodecanethiol

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

PubMed

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

2009-07-17

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

Pseudomonas aeruginosa quorum sensing molecules correlate with clinical status in cystic fibrosis.

PubMed

Barr, Helen L; Halliday, Nigel; Cámara, Miguel; Barrett, David A; Williams, Paul; Forrester, Douglas L; Simms, Rebecca; Smyth, Alan R; Honeybourne, David; Whitehouse, Joanna L; Nash, Edward F; Dewar, Jane; Clayton, Andrew; Knox, Alan J; Fogarty, Andrew W

2015-10-01

Pseudomonas aeruginosa produces quorum sensing signal molecules that are potential biomarkers for infection.A prospective study of 60 cystic fibrosis patients with chronic P. aeruginosa, who required intravenous antibiotics for pulmonary exacerbations, was undertaken. Clinical measurements and biological samples were obtained at the start and end of the treatment period. Additional data were available for 29 of these patients when they were clinically stable.Cross-sectionally, quorum sensing signal molecules were detectable in the sputum, plasma and urine of 86%, 75% and 83% patients, respectively. They were positively correlated between the three biofluids. Positive correlations were observed for most quorum sensing signal molecules in sputum, plasma and urine, with quantitative measures of pulmonary P. aeruginosa load at the start of a pulmonary exacerbation. Plasma concentrations of 2-nonyl-4-hydroxy-quinoline (NHQ) were significantly higher at the start of a pulmonary exacerbation compared to clinical stability (p<0.01). Following the administration of systemic antibiotics, plasma 2-heptyl-4-hydroxyquinoline (p=0.02) and NHQ concentrations (p<0.01) decreased significantly.In conclusion, quorum sensing signal molecules are detectable in cystic fibrosis patients with pulmonary P. aeruginosa infection and are positively correlated with quantitative measures of P. aeruginosa. NHQ correlates with clinical status and has potential as a novel biomarker for P. aeruginosa infection. Copyright ©ERS 2015.

Controlled manipulation of the Co-Alq3 interface by rational design of Alq3 derivatives.

PubMed

Großmann, Nicolas; Magri, Andrea; Laux, Martin; Stadtmüller, Benjamin; Thielen, Philip; Schäfer, Bernhard; Fuhr, Olaf; Ruben, Mario; Cinchetti, Mirko; Aeschlimann, Martin

2016-11-15

Recently, research has revealed that molecules can be used to steer the local spin properties of ferromagnetic surfaces. One possibility to manipulate ferromagnetic-metal-molecule interfaces in a controlled way is to synthesize specific, non-magnetic molecules to obtain a desired interaction with the ferromagnetic substrate. Here, we have synthesized derivatives of the well-known semiconductor Alq 3 (with q = 8-hydroxyquinolinate), in which the 8-hydroxyquinolinate ligands are partially or completely replaced by similar ligands bearing O- or N-donor sets. The goal of this study was to investigate how the presence of (i) different donor atom sets and (ii) aromaticity in different conjugated π-systems influences the spin properties of the metal-molecule interface formed with a Co(100) surface. The spin-dependent metal-molecule-interface properties have been measured by spin-resolved photoemission spectroscopy, backed up by DFT calculations. Overall, our results show that, in the case of the Co-molecule interface, chemical synthesis of organic ligands leads to specific electronic properties of the interface, such as exciton formation or highly spin-polarized interface states. We find that these properties are even additive, i.e. they can be engineered into one single molecular system that incorporates all the relevant ligands.

Influence of high hydrostatic pressure on Alq3, Gaq3, and Inq3 (q = 8-hydroxyquinoline).

PubMed

Hernández, Ignacio; Gillin, William P

2009-10-29

We have studied the spectroscopic properties of OLED materials Alq(3), Gaq(3) and Inq(3) (q = 8-hydroxyquinoline) under pressure. We discuss the results in terms of the influence of structural modifications, the isomeric state and the enhancement of the intermolecular interaction. As-grown Alq(3), Gaq(3), Inq(3) containing meridional (mer) isomer experience a red shift of nearly 90 nm (2400 cm(-1)) in the 0-8 GPa range. Abrupt changes in the photoluminescence occur during compression at intermediate pressures for all materials. We assign them to a phase transition, its critical pressure depending on the central cation. All three samples experience an amorphization at P approximately 6 GPa, with associated changes in the spectroscopic properties. The pressure-induced phase transitions present hysteresis to ambient conditions. Photoluminescence lifetime decreases in all cases in the explored pressure range. In the case of facial isomer containing polymorphs of Alq(3), luminescence does not change its energy significantly. The most significant spectroscopic change observed in fac-isomer containing materials corresponds to gamma-Alq(3), which presents a low energy component that gains relative importance when pressure is increased. We ascribe this phenomenon to the presence of sensitized mer isomer impurities.

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. © 2012 American Chemical Society

Pseudomonas aeruginosa quorum sensing molecules correlate with clinical status in cystic fibrosis

PubMed Central

Halliday, Nigel; Cámara, Miguel; Barrett, David A.; Williams, Paul; Forrester, Douglas L.; Simms, Rebecca; Smyth, Alan R.; Honeybourne, David; Whitehouse, Joanna L.; Nash, Edward F.; Dewar, Jane; Clayton, Andrew; Knox, Alan J.; Fogarty, Andrew W.

2015-01-01

Pseudomonas aeruginosa produces quorum sensing signal molecules that are potential biomarkers for infection. A prospective study of 60 cystic fibrosis patients with chronic P. aeruginosa, who required intravenous antibiotics for pulmonary exacerbations, was undertaken. Clinical measurements and biological samples were obtained at the start and end of the treatment period. Additional data were available for 29 of these patients when they were clinically stable. Cross-sectionally, quorum sensing signal molecules were detectable in the sputum, plasma and urine of 86%, 75% and 83% patients, respectively. They were positively correlated between the three biofluids. Positive correlations were observed for most quorum sensing signal molecules in sputum, plasma and urine, with quantitative measures of pulmonary P. aeruginosa load at the start of a pulmonary exacerbation. Plasma concentrations of 2-nonyl-4-hydroxy-quinoline (NHQ) were significantly higher at the start of a pulmonary exacerbation compared to clinical stability (p<0.01). Following the administration of systemic antibiotics, plasma 2-heptyl-4-hydroxyquinoline (p=0.02) and NHQ concentrations (p<0.01) decreased significantly. In conclusion, quorum sensing signal molecules are detectable in cystic fibrosis patients with pulmonary P. aeruginosa infection and are positively correlated with quantitative measures of P. aeruginosa. NHQ correlates with clinical status and has potential as a novel biomarker for P. aeruginosa infection. PMID:26022946

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

PubMed

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

2010-10-15

A cloud point extraction (CPE) method has been developed for the determination of trace quantity of vanadium ions in pharmaceutical formulations (PF), dialysate (DS) and parenteral solutions (PS). The CPE of vanadium (V) using 8-hydroxyquinoline (oxine) as complexing reagent and mediated by nonionic surfactant (Triton X-114) was investigated. The parameters that affect the extraction efficiency of CPE, such as pH of sample solution, concentration of oxine and Triton X-114, equilibration temperature and time period for shaking were investigated in detail. The validity of CPE of V was checked by standard addition method in real samples. The extracted surfactant-rich phase was diluted with nitric acid in ethanol, prior to subjecting electrothermal atomic absorption spectrometry. Under these conditions, the preconcentration of 50 mL sample solutions, allowed raising an enrichment factor of 125-fold. The lower limit of detection obtained under the optimal conditions was 42 ng/L. The proposed method has been successfully applied to the determination of trace quantity of V in various pharmaceutical preparations with satisfactory results. The concentration ranges of V in PF, DS and PS samples were found in the range of 10.5-15.2, 0.65-1.32 and 1.76-6.93 microg/L, respectively. 2010 Elsevier B.V. All rights reserved.

Accelerating Quinoline Biodegradation and Oxidation with Endogenous Electron Donors.

PubMed

Bai, Qi; Yang, Lihui; Li, Rongjie; Chen, Bin; Zhang, Lili; Zhang, Yongming; Rittmann, Bruce E

2015-10-06

Quinoline, a recalcitrant heterocyclic compound, is biodegraded by a series of reactions that begin with mono-oxygenations, which require an intracellular electron donor. Photolysis of quinoline can generate readily biodegradable products, such as oxalate, whose bio-oxidation can generate endogenous electron donors that ought to accelerate quinoline biodegradation and, ultimately, mineralization. To test this hypothesis, we compared three protocols for the biodegradation of quinoline: direct biodegradation (B), biodegradation after photolysis of 1 h (P1h+B) or 2 h (P2h+B), and biodegradation by adding oxalate commensurate to the amount generated from photolysis of 1 h (O1+B) or 2 h (O2+B). The experimental results show that P1h+B and P2h+B accelerated quinoline biodegradation by 19% and 50%, respectively, compared to B. Protocols O1+B and O2+B also gave 19% and 50% increases, respectively. During quinoline biodegradation, its first intermediate, 2-hydroxyquinoline, accumulated gradually in parallel to quinoline loss but declined once quinoline was depleted. Mono-oxygenation of 2-hydroxyquinoline competed with mono-oxygenation of quinoline, but the inhibition was relieved when extra electrons donors were added from oxalate, whether formed by UV photolysis or added exogenously. Rapid oxalate oxidation stimulated both mono-oxygenations, which accelerated the overall quinoline oxidation that provided the bulk of the electron donor.

8-Hydroxyquinoline and hydroxamic acid inhibitors of botulinum neurotoxin BoNT/A.

PubMed

Dickerson, Tobin J; Smith, Garry R; Pelletier, Jeffrey C; Reitz, Allen B

2014-01-01

We describe here the state of the art of certain aspects concerning potential small molecule therapy directed toward botulism, by inhibition of the zinc-protease containing light chain (LC) of botulinum neurotoxin BoNT/A from the anaerobic bacillus Clostridium botulinum. Botulinum neurotoxins (BoNTs) are comprised of eight serologically-distinct proteins (A - H), several of which are further divided, such as BoNT/A which has five subtypes. The BoNTs are the most toxic substances known to mankind, causing a form of flaccid paralysis that can be rapid and is often lethal. BoNT/A is comprised of a ~100 kDa heavy chain (HC) attached via a single disulfide Cys-Cys bond to a ~50 kDa LC. The HC mediates transport to and uptake by presynaptic glutamatergic neurons, where the LC cleaves the protein SNAP-25 and thus prevents vesicular trafficking and release of acetylcholine. The Zn-endoprotease activity of the LC of BoNT/A is a target for the development of small molecule inhibitors of BoNT/A-mediated toxicity. A variety of BoNT/A LC inhibitors have been described to date and we focus here primarily on the Zn-binding 8-hydroxyquinoline structural type as well as some of the previously-described hydroxamic acids.

Oligonucleotide assisted light-emitting Alq3 microrods: energy transfer effect with fluorescent dyes.

PubMed

Cui, Chunzhi; Park, Dong Hyuk; Kim, Jeongyong; Joo, Jinsoo; Ahn, Dong June

2013-06-14

Oligonucleotide assisted tri(8-hydroxyquinoline) aluminium (Alq3) microrods were prepared for the first time. When hybridized with oligonucleotide labeled by Cy3 fluorescent dye, a significant photoluminescence variation of the Alq3 microrods was observed due to Förster resonance energy transfer, unlike when Cy5-oligonucleotide was used. Versatile nucleotide manipulation would open up wider applications of Alq3-based materials, based on this fundamental observation.

SEPARATION PROCESS USING COMPLEXING AND ADSORPTION

DOEpatents

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

1958-06-01

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

Gold(III) complexes with hydroxyquinoline, aminoquinoline and quinoline ligands: Synthesis, cytotoxicity, DNA and protein binding studies.

PubMed

Martín-Santos, Cecilia; Michelucci, Elena; Marzo, Tiziano; Messori, Luigi; Szumlas, Piotr; Bednarski, Patrick J; Mas-Ballesté, Rubén; Navarro-Ranninger, Carmen; Cabrera, Silvia; Alemán, José

2015-12-01

In this article, we report on the synthesis and the chemical and biological characterization of novel gold(III) complexes based on hydroxyl- or amino-quinoline ligands that are evaluated as prospective anticancer agents. To gain further insight into their reactivity and possible mode of action, their interactions with model proteins and standard nucleic acid molecules were investigated. Copyright © 2015 Elsevier Inc. All rights reserved.

Encapsulation of anticancer drug copper bis(8-hydroxyquinoline) in hydroxyapatite for pH-sensitive targeted delivery and slow release.

PubMed

Weerasuriya, D R K; Wijesinghe, W P S L; Rajapakse, R M G

2017-02-01

There is a conspicuous progress in increasing anticancer drug delivery through the utilization of nanoparticles (NPs) as drug delivery agents. Hydroxyapatite (HA) gives improved clinical effectiveness of drugs by reducing systemic toxicity and broadening the spectrum of drug delivery since it is biocompatible and it can be targeted towards tumor cells. Herein, investigation of the potential of enhancing controlled drug release of the template model drug, copper bis-(8-hydroxyquinoline), by encapsulating it in hollow hydroxyapatite nano-carriers, is presented. Hydroxyapatite nanoparticles are synthesized by following four different routes to optimize its efficacy of drug loading. Copper bis-(8-hydroxyquinoline) is encapsulated by Method (a) which was effected by stirring the model drug and porous HA NPs in colloidal solution and Method (b) which was done during synthesis of hydroxyapatite nanoparticles in a solution of the model drug. In synthesizing nanoporous HA NPs, calcium carbonate is used as a template to create voids in HA. In each method, Ca/P ratio was ensured to be kept at 1.67:1. Appealing results are reported for the encapsulated product which was prepared by Method (a2). Method (a) was done at three different molar ratios of PO 4 3- :CO 3 2- and best result was obtained for that utilized 2.003:1 molar ratio (Method (a2).). It produced 98.67% of encapsulation efficiency and 2.9522mg/g of drug loading capacity. Release kinetics was studied at a range of pH values; the lower the pH of the medium the higher is the drug release. For instance, when considering the product which exhibited high encapsulation efficiency and high drug loading capacity, at pH3.5 during the first 8h it elicited about 13% of release, at pH5.0 about 8% release while at pH6.0 it was just 2.5%. During the 24-hour span, pH3.5 exhibited about 23.8%, at pH5.0 approximately 9% with an increasing trend of release and at pH6.0 showed a value just above 2.5%. As such, acidity of the cancerous cells can be made use to increase the drug slow-release kinetics at the vicinity of the cancer cells. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation of 8-hydroxyquinoline derivatives as potential antibiotics against Staphylococcus aureus.

PubMed

Lam, Kim-Hung; Gambari, Roberto; Lee, Kenneth Ka-Ho; Chen, Yi-Xin; Kok, Stanton Hon-Lung; Wong, Raymond Siu-Ming; Lau, Fung-Yi; Cheng, Chor-Hing; Wong, Wai-Yeung; Bian, Zhao-Xiang; Chan, Albert Sun-Chi; Tang, Johnny Cheuk-On; Chui, Chung-Hin

2014-01-01

This work describes the preparation of quinoline compounds as possible anti-bacterial agents. The synthesized quinoline derivatives show anti-bacterial activity towards Staphylococcus aureus. It is interesting to observe that the synthetic 5,7-dibromo-2-methylquinolin-8-ol (4) shows a similar minimum inhibitory concentration of 6.25μg/mL as compared to that of methicillin (3.125μg/mL) against Staphylococcus aureus. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

PubMed

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

2013-11-15

Vanadium(V) ions as 8-hydroxyquinoline chelates were loaded on multiwalled carbon nanotubes (MWNTs) in a mini chromatographic column. Vanadium was determined by graphite furnace atomic absorption spectrometry (GFAAS). Various analytical parameters including pH of the working solutions, amounts of 8-hydroxyquinoline, eluent type, sample volume, and flow rates were investigated. The effects of matrix ions and some transition metals were also studied. The column can be reused 250 times without any loss in its sorption properties. The preconcentration factor was found as 100. Detection limit (3 s) and limit of quantification (10 s) for the vanadium in the optimal conditions were observed to be 0.012 µg L(-1) and 0.040 μg L(-1), respectively. The capacity of adsorption was 9.6 mg g(-1). Relative standard deviation (RSD) was found to be 5%. The validation of the method was confirmed by using NIST SRM 1515 Apple leaves, NIST SRM 1570a Spinach leaves and GBW 07605 Tea certified reference materials. The procedure was applied to the determination of vanadium in tap water and bottled drinking water samples. The procedure was also successfully applied to microwave digested food samples including black tea, coffee, tomato, cabbage, zucchini, apple and chicken samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Chemical Modification and Detoxification of the Pseudomonas aeruginosa Toxin 2-Heptyl-4-hydroxyquinoline N-Oxide by Environmental and Pathogenic Bacteria.

PubMed

Thierbach, Sven; Birmes, Franziska S; Letzel, Matthias C; Hennecke, Ulrich; Fetzner, Susanne

2017-09-15

2-Heptyl-4-hydroxyquinoline N-oxide (HQNO), a major secondary metabolite and virulence factor produced by the opportunistic pathogen Pseudomonas aeruginosa, acts as a potent inhibitor of respiratory electron transfer and thereby affects host cells as well as microorganisms. In this study, we demonstrate the previously unknown capability of environmental and pathogenic bacteria to transform and detoxify this compound. Strains of Arthrobacter and Rhodococcus spp. as well as Staphylococcus aureus introduced a hydroxyl group at C-3 of HQNO, whereas Mycobacterium abscessus, M. fortuitum, and M. smegmatis performed an O-methylation, forming 2-heptyl-1-methoxy-4-oxoquinoline as the initial metabolite. Bacillus spp. produced the glycosylated derivative 2-heptyl-1-(β-d-glucopyranosydyl)-4-oxoquinoline. Assaying the effects of these metabolites on cellular respiration and on quinol oxidase activity of membrane fractions revealed that their EC 50 values were up to 2 orders of magnitude higher than that of HQNO. Furthermore, cellular levels of reactive oxygen species were significantly lower in the presence of the metabolites than under the influence of HQNO. Therefore, the capacity to transform HQNO should lead to a competitive advantage against P. aeruginosa. Our findings contribute new insight into the metabolic diversity of bacteria and add another layer of complexity to the metabolic interactions which likely contribute to shaping polymicrobial communities comprising P. aeruginosa.

Uranium(VI) Complexes with a Calix[4]arene‐Based 8‐Hydroxyquinoline Ligand: Thermodynamic and Structural Characterization Based on Calorimetry, Spectroscopy, and Liquid–Liquid Extraction

PubMed Central

Bauer, Anne; Jäschke, Astrid; Schöne, Sebastian; Barthen, Robert; März, Juliane; Patzschke, Michael; Kersting, Berthold; Fahmy, Karim; Oertel, Jana; Brendler, Vinzenz; Stumpf, Thorsten

2018-01-01

Abstract The environmental aspects of ore processing and waste treatment call for an optimization of applied technologies. There, understanding of the structure and complexation mechanism on a molecular scale is indispensable. Here, the complexation of UVI with a calix[4]arene‐based 8‐hydroxyquinoline ligand was investigated by applying a wide range of complementary methods. In solution, the formation of two complex species was proven with stability constants of log ß 1:1=5.94±0.02 and log ß 2:1=6.33±0.01, respectively. The formation of the 1:1 complex was found to be enthalpy driven [ΔH 1:1=(−71.5±10.0) kJ mol−1; TΔS 1:1=(−37.57±10.0) kJ mol−1], whereas the second complexation step was found to be endothermic and entropy driven [ΔH 2:1=(32.8±4.0) kJ mol−1; TΔS 2:1=(68.97±4.0) kJ mol−1]. Moreover, the molecular structure of [UO2(H6L)(NO3)](NO3) (1) was determined by single‐crystal X‐ray diffraction. Concluding, radiotoxic UVI was separated from a EuIII‐containing solution by the calix[4]arene‐based ligand in solvent extractions. PMID:29930893

Visible and NIR photoluminescence properties of a series of novel lanthanide-organic coordination polymers based on hydroxyquinoline-carboxylate ligands.

PubMed

Gai, Yan-Li; Xiong, Ke-Cai; Chen, Lian; Bu, Yang; Li, Xing-Jun; Jiang, Fei-Long; Hong, Mao-Chun

2012-12-17

A series of novel two-dimensional (2D) lanthanide coordination polymers with 4-hydroxyquinoline-2-carboxylate (H(2)hqc) ligands, [Ln(Hhqc)(3)(H(2)O)](n)·3nH(2)O (Ln = Eu (1), Tb (2), Sm (3), Nd (4), and Gd (5)) and [Ln(Hhqc)(ox)(H(2)O)(2)](n) (Ln = Eu (6), Tb (7), Sm (8), Tm (9), Dy (10), Nd (11), Yb (12), and Gd (13); H(2)ox = oxalic acid), have been synthesized under hydrothermal conditions. Complexes 1-5 are isomorphous, which can be described as a two-dimensional (2D) hxl/Shubnikov network based on Ln(2)(CO(2))(4) paddle-wheel units, and the isomorphous complexes 6-13 feature a 2D decker layer architecture constructed by Ln-ox infinite chains cross-linked alternatively by bridging Hhqc(-) ligands. The room-temperature photoluminescence spectra of complexes Eu(III) (1 and 6), Tb(III) (2 and 7), and Sm(III) (3 and 8) exhibit strong characteristic emissions in the visible region, whereas Nd(III) (4 and 11) and Yb(III) (12) complexes display NIR luminescence upon irradiation at the ligand band. Moreover, the triplet state of H(2)hqc matches well with the emission level of Eu(III), Tb(III), and Sm(III) ions, which allows the preparation of new optical materials with enhanced luminescence properties.

Absorption spectra of 4f electron transitions of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid and diethylamine systems and its analytical application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Naixing; Qi Ping

1992-06-01

In this paper the absorption spectra of 4f electron transitions of the systems of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid and diethylamine have been studied by normal and third-derivative spectrophotometry. Their molar absorptivities are 80 1.mol{sup {minus}1}.cm{sup {minus}1} for neodymium and 65 1.mol{sup {minus}1}.cm{sup {minus}1} for erbium. Use of the third-derivative spectra, eliminates the interference by other rare earths and increases the sensitivity for Nd and Er. The derivative molar absorptivities are 390 1.mol{sup {minus}1}.cm{sup {minus}1} for Nd and 367 1.mol{sup {minus}1}.cm{sup {minus}1} for Er. The calibration graphs were linear up to 11.8 {mu}g/ml of Nd and 12.3 {mu}g/ml ofmore » Er, respectively. The relative standard deviations evaluated from eleven independent determinations of 7.2 {mu}g/ml (for Nd) and 8.3 {mu}g/ml (for Er) are 1.3% and 1.4%, respectively. The detection limits are 0.2 {mu}g/ml for Nd and 0.3 {mu}g/ml for Er. The method has been developed for determining those two elements in mixture of lanthanides by means of the third-derivative spectra and the analytical results obtained are satisfactory.« less

Direct Printing of Organic Electronics at the Nanometer Scale

DTIC Science & Technology

2006-02-01

patterning as seen in Figure 3. Also, a flat film OVJP grown Alq3 NPD OLED was shown to be competitive with VTE with quantum efficiencies of 0.84%. 0 0...a tris(8-hydroxyquinoline)- aluminum ( Alq3 ) electron transport and emitting layer. The OLEDs exhibited an external 8 quantum efficiency of (0.84...parameter analyzer and a Newport Model 2932-C dual-channel power meter. An OLED having the layer structure: ITO/60nm NPD/60nm Alq3 /LiF:Al was deposited

A Diarylethene Derived Chemosensor for Colorimetric Sensing of Cu2+

NASA Astrophysics Data System (ADS)

Pu, Shouzhi; Sun, Qi; Zheng, Chunhong

2017-07-01

A diarylethene bearing a 8-hydroxyquinoline-linked salicylhydrazide Schift base unit has been synthesized. In CH3CN, the conpound displayed a highly selective and sensitive response to Cu2+ via perceptible color and UV-vis absorbance changes among the other tested metal ions. In the presence of Cu2+, the peak at 341 nm disappeared and concomitantly a new charge transfer absorption band emerged at 381 and 450 nm. Moreover, the compound formed host-guest complexe in 1:1 stoichiometry.

Further characterization of Bacillus subtilis antibiotic biosensors and their use for antibacterial mode-of-action studies.

PubMed

Mariner, Katherine R; Ooi, Nicola; Roebuck, Deborah; O'Neill, Alex J; Chopra, Ian

2011-04-01

We further examined the usefulness of previously reported Bacillus subtilis biosensors for antibacterial mode-of-action studies. The biosensors could not detect the tRNA synthetase inhibitors mupirocin, indolmycin, and borrelidin, some inhibitors of peptidoglycan synthesis, and most membrane-damaging agents. However, the biosensors confirmed the modes of action of several RNA polymerase inhibitors and DNA intercalators and provided new insights into the possible modes of action of ciprofloxacin, anhydrotetracycline, corralopyronin, 8-hydroxyquinoline, and juglone.

Highly effective synthesis of a cobalt(ii) metal-organic coordination polymer by using continuous flow chemistry.

PubMed

Gong, Chunhua; Zhang, Junyong; Zeng, Xianghua; Xie, Jingli

2016-12-20

The coordination polymer [Co 2 L 4 (H 2 O) 2 ]·CH 3 CN·H 2 O (HL = (E)-2-[2-(4-chlorophenyl)vinyl]-8-hydroxyquinoline) has been achieved with 95% yield by using an Asia flow synthesis system (chip reactor). Compared with the conventional batch-type methods such as diffusion, reflux and solvothermal reactions, higher yielding reactions carried out in a flow reactor have demonstrated that this technique is a powerful strategy to obtain coordination compounds.

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. 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)/2,21-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

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

NASA Astrophysics Data System (ADS)

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

2010-03-01

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

Ground-State Charge-Density Distribution in a Crystal of the Luminescent ortho-Phenylenediboronic Acid Complex with 8-Hydroxyquinoline.

PubMed

Jarzembska, Katarzyna N; Kamiński, Radosław; Durka, Krzysztof; Woźniak, Krzysztof

2018-05-10

This contribution is devoted to the first electron density studies of a luminescent oxyquinolinato boron complex in the solid state. ortho-Phenylenediboronic acid mixed with 8-hydroxyquinoline in dioxane forms high-quality single crystals via slow solvent evaporation, which allows successful high resolution data collection (sin θ/λ = 1.2 Å -1 ) and charge density distribution modeling. Particular attention has been paid to the boron-oxygen fragment connecting the two parts of the complex, and to the solvent species exhibiting anharmonic thermal motion. The experiment and theory compared rather well in terms of atomic charges and volumes, except for the boron centers. Boron atoms, as expected, constitute the most electron-deficient species in the complex molecule, whereas the neighboring oxygen and carbon atoms are the most significantly negatively charged ones. This part of the molecule appears to be very much involved in the charge transfer occurring between the acid fragment and oxyquinoline moiety leading to the observed fluorescence, as supported by the time-dependent density functional theory (TDDFT) results and the generated transition density maps. TDDFT calculations indicated that p-type atomic orbitals contributing to the HOMO-1, HOMO, and LUMO play the major role in the lowest energy transitions, and enabled further comparison with the charge density features, which is discussed in details. Furthermore, the results confirmed the known fact the Q ligand character is most important for the spectroscopic properties of this class of complexes.

In Vitro Selective Growth-Inhibitory Effect of 8-Hydroxyquinoline on Clostridium perfringens versus Bifidobacteria in a Medium Containing Chicken Ileal Digesta.

PubMed

Skrivanova, Eva; Van Immerseel, Filip; Hovorkova, Petra; Kokoska, Ladislav

2016-01-01

Clostridium perfringens-induced necrotic enteritis is generally controlled by antibiotics. However, because of increasing antibiotic resistance, other antibacterial agents are required, preferably ones that do not affect the beneficial intestinal microbiota of the host. This study evaluated the in vitro selective growth-inhibitory effect of 8-hydroxyquinoline (8HQ) on C. perfringens vs. bifidobacteria in a medium containing chicken ileal digesta. Prior to the experiments, the minimum inhibitory concentrations of 8HQ and penicillin G were determined by broth microdilution assay. The minimum inhibitory concentration values of 8HQ for C. perfringens were 16-32 times lower than the values for bifidobacteria. Treatment of autoclaved and non-autoclaved chicken ileal digesta with 8HQ showed a selective anticlostridial effect. After incubation of C. perfringens with autoclaved ileal digesta for 3 h, all 8HQ concentrations tested (32-2048 μg/mL) significantly reduced C. perfringens bacterial count. In contrast, the same treatment had no or only a slight effect on bifidobacteria counts. Unlike 8HQ, penicillin G did not exhibit any selectivity. Similar results were obtained after incubation for 24 h. In non-autoclaved ileal digesta, all 8HQ concentrations tested significantly reduced C. perfringens bacterial counts after incubation for 30 min and 3 h, while no effect was observed on bifidobacteria. These results suggest that 8HQ may serve as a prospective veterinary compound for use against necrotic enteritis in poultry.

A Molecular Beam Deposition of DNA Nanometer Films

DTIC Science & Technology

2007-01-01

device structure consists of ITO/PEDOT:PSS (50 nm)/NPB (30 nm)/ Alq3 (40 nm)/BCP (20 nm)/ Alq3 (10 nm)/Li:Al, while the Bi- OLED has an additional DNA...layer; DNA- CTMA is an electron blocking layer (EBL); NPB is used as hole transport layer; Alq3 is used for both the electron transport layer and the...N,N’-bis(naphthalen-1-yl)-N,N’- bis(phenyl)benzidine)], Alq3 [tris-(8-hydroxyquinoline) aluminum] and BCP [2,9- Dimethyl-4,7-diphenyl-1,10

Emission color tuning in AlQ3 complexes with extended conjugated chromophores.

PubMed

Pohl, Radek; Anzenbacher, Pavel

2003-08-07

[reaction: see text] A new method for the synthesis of 5-arylethynyl-8-hydroxyquinoline ligands using Sonogashira-Hagihara coupling was developed. The electronic nature of arylethynyl substituents affects the emission color and quantum yield of the resulting Al(III) complex. Photophysical properties of the metallocomplexes correspond to the electron-withdrawing/-donating character of the arylethynyl substituents. Optical properties of such Al(III) complexes correlate with the Hammett constant values of the respective substituents. This strategy offers a powerful tool for the preparation of electroluminophores with predictable photophysical properties.

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

PubMed

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

2009-01-01

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

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

Effects of a tacrine-8-hydroxyquinoline hybrid (IQM-622) on Aβ accumulation and cell death: involvement in hippocampal neuronal loss in Alzheimer's disease.

PubMed

Antequera, Desiree; Bolos, Marta; Spuch, Carlos; Pascual, Consuelo; Ferrer, Isidro; Fernandez-Bachiller, María Isabel; Rodríguez-Franco, María Isabel; Carro, Eva

2012-06-01

Several studies have implicated the enzyme acetylcholinesterase (AChE) as well as several biometals in the pathogenesis of Alzheimer's disease (AD). A multifunctional molecule, the hybrid tacrine-8-hydroxyquinoline (named IQM-622), displays cholinergic, antioxidant, copper-complexing and neuroprotective properties. Using in vitro and in vivo models, we investigated the modulating effects of IQM-622 on amyloid β-protein (Aβ)-induced pathology as well as on chemically induced neurodegeneration by domoic acid. In the first experimental model, we observed a significant decrease in brain Aβ deposits in IQM-622-treated APP/Ps1 mice for four weeks. Moreover, IQM-622 promoted the degradation of intracellular Aβ in astrocytes, and protected against Aβ toxicity in cultured astrocytes and neurons. These findings suggest that the neuroprotective effect of IQM-622 is not only related to AChE inhibition, but also involves other mechanisms, including the modulation of Aβ-degradation pathways in AD brain. In this study we also compare the neuronal loss in CA1 hippocampal field of AD patients and of mice treated with domoic acid, giving similar patterns. Thus, we used a second experimental model by killing hippocampal neurons by domoic acid damage, in which IQM-622 increased survival in the CA1 and dentate gyrus regions of the hippocampus. Our observations suggest that administration of IQM-622 may have significant beneficial effects in neurodegenerative diseases, including AD, which course with acute or progressive neuronal death. Copyright © 2012. Published by Elsevier Inc.

CP/MAS 13C NMR characterization of the isomeric states and intermolecular packing in tris(8-hydroxyquinoline) aluminum(III) (Alq3).

PubMed

Kaji, Hironori; Kusaka, Yasunari; Onoyama, Goro; Horii, Fumitaka

2006-04-05

The isomeric states and intermolecular packing of tris(8-hydroxyquinoline) aluminum(III) (Alq(3)) in the alpha-, gamma-, and delta-crystalline forms and in the amorphous state, which are important for understanding the light-emitting and electron-transport properties, have been analyzed by CP/MAS (13)C NMR. This simple NMR experiment shows that the isomeric state of alpha- and amorphous Alq(3) is meridional, whereas that of gamma- and delta-Alq(3) is facial. In the amorphous Alq(3), the inclusion of facial isomers has been under debate. Our experiments show that meridional isomers are dominant in the amorphous Alq(3), although the existence of facial isomers cannot be completely denied. The local structure of amorphous Alq(3) is similar to that of alpha-Alq(3) and is significantly different from those of gamma- and delta-Alq(3). Among these Alq(3) samples, the effect of intermolecular interaction is not found only for gamma-Alq(3). This finding can explain the good solvent solubility of gamma-Alq(3), compared with the other crystalline forms. It is also shown that the structures are locally disordered not only for amorphous Alq(3) but also for alpha-Alq(3), although clear X-ray diffraction peaks are observed for alpha-Alq(3). In contrast, the local structures of gamma- and delta-Alq(3) are well defined. A clear relation is found between the spectral patterns of CP/MAS (13)C NMR and the fluorescence wavelengths; the samples, which consist of facial isomers, show blue-shifted fluorescence compared with those of meridionals.

NMR Reveals Double Occupancy of Quinone-type Ligands in the Catalytic Quinone Binding Site of the Na+-translocating NADH:Quinone Oxidoreductase from Vibrio cholerae*

PubMed Central

Nedielkov, Ruslan; Steffen, Wojtek; Steuber, Julia; Möller, Heiko M.

2013-01-01

The sodium ion-translocating NADH:quinone oxidoreductase (Na+-NQR) from the pathogen Vibrio cholerae exploits the free energy liberated during oxidation of NADH with ubiquinone to pump sodium ions across the cytoplasmic membrane. The Na+-NQR consists of four membrane-bound subunits NqrBCDE and the peripheral NqrF and NqrA subunits. NqrA binds ubiquinone-8 as well as quinones with shorter prenyl chains (ubiquinone-1 and ubiquinone-2). Here we show that the quinone derivative 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), a known inhibitor of the bc1 and b6f complexes found in mitochondria and chloroplasts, also inhibits quinone reduction by the Na+-NQR in a mixed inhibition mode. Tryptophan fluorescence quenching and saturation transfer difference NMR experiments in the presence of Na+-NQR inhibitor (DBMIB or 2-n-heptyl-4-hydroxyquinoline N-oxide) indicate that two quinone analog ligands are bound simultaneously by the NqrA subunit with very similar interaction constants as observed with the holoenzyme complex. We conclude that the catalytic site of quinone reduction is located on NqrA. The two ligands bind to an extended binding pocket in direct vicinity to each other as demonstrated by interligand Overhauser effects between ubiquinone-1 and DBMIB or 2-n-heptyl-4-hydroxyquinoline N-oxide, respectively. We propose that a similar spatially close arrangement of the native quinone substrates is also operational in vivo, enhancing the catalytic efficiency during the final electron transfer steps in the Na+-NQR. PMID:24003222

Photoluminescence and Coordination Behaviour of Lanthanide Complexes of Tris (Aminomethyl)Ethane-5-Oxine in Aqueous Solution.

PubMed

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

2017-01-01

Photophysical properties of a multidentate tripodal ligand, 5,5'-(2-(((8-hydroxyquinolin-5-yl) methylamino)methyl)-2-methylpropane-1,3-diyl) bis (azanediyl)bis (methylene)diquinolin-8-ol, (TAME5OX), with La 3+ and Er 3+ ions have been examined for photonics applications. The change in behavior in electronic spectra of these complexes reveals the use of TAME5OX as a sensitive optical pH based sensor to detect Ln 3+ ions whereas indication of strong green fluorescence allows simultaneous sensing within the visible region in competitive medium. The intense fluorescence intermittently gets quenched under acidic and basic conditions due to photoinduced intramolecular electron transfer from the excited 8-hydroxyquinoline (8-HQ) moiety to the metal ion. This renders these compounds the OFF-ON-OFF type of pH-dependent fluorescent sensor. The thermodynamic stability and coordination behaviour of the chelator with the said lanthanide ions have also been probed by potentiometric, UV - visible and fluorescence spectrophotometric method. TAME5OX forms protonated complex [Ln (H 4 L)] 4+ below pH ~4.0 which sequentially deprotonates through one proton process with increase of pH. The stability constants of neutral complexes have been determined to be in the range log β 110  = 32-34 and pLn in the range of 14-20, indicating TAME5OX is a good synthetic lanthanide chelator. Theoretical spectra were also calculated by ZINDO/s methodology at single excitations (CIS) level on PM7 as sparkle energy-minimized geometries.

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.

Synthesis and antiplasmodial evaluation of novel (4-aminobutyloxy)quinolines.

PubMed

Vandekerckhove, Stéphanie; Müller, Christian; Vogt, Dieter; Lategan, Carmen; Smith, Peter J; Chibale, Kelly; De Kimpe, Norbert; D'hooghe, Matthias

2013-01-01

A variety of 5-, 6- and 8-(4-aminobutyloxy)quinolines as novel oxygen analogues of known 4- and 8-(4-aminobutylamino)quinoline antimalarial drugs was generated from hydroxyquinolines through a three-step approach with a rhodium-catalyzed hydroformylation as the key step. Antiplasmodial assays of these new quinolines revealed micromolar potency for all representatives against a chloroquine-sensitive strain of Plasmodium falciparum, and three compounds showed submicromolar activity against a chloroquine-resistant strain of P. falciparum with IC(50)-values ranging between 150 and 680 nM. Copyright © 2012 Elsevier Ltd. All rights reserved.

Erbium Doped Quantum Dot and Si:O and Plasmon Resonance Enabled Quantum Dot Nanoscale Lasers

DTIC Science & Technology

2009-08-31

electroluminescence has to be coupled with a high-Q cavity for lasing. Alq3 PEDOT:PSS ITO — • MEHPPV +PbSe QDs . • •A iz^————— Gold (Au...PEDOT:PSS on the ITO anode and Alq3 /Ca/Al cathode. The inset is a SEM image of the L3 defect photonic crystal microcavity in silicon. Outer air holes at...consisting of tris(8-hydroxyquinoline)aluminum ( Alq3 ), calcium, and aluminum. The device heterostructure is schematically shown in Fig. 5(a). The ITO

Structure of Co-Doped Alq3 thin films investigated by grazing incidence X-ray absorption fine structure and Fourier transform infrared spectroscopy.

PubMed

Lin, Liang; Pang, Zhiyong; Fang, Shaojie; Wang, Fenggong; Song, Shumei; Huang, Yuying; Wei, Xiangjun; Yu, Haisheng; Han, Shenghao

2011-02-10

The structural properties of Co-doped tris(8-hydroxyquinoline)aluminum (Alq(3)) have been studied by grazing incidence X-ray absorption fine structure (GIXAFS) and Fourier transform infrared spectroscopy (FTIR). GIXAFS analysis suggests that there are multivalent Co-Alq(3) complexes and the doped Co atoms tend to locate at the attraction center with respect to N and O atoms and bond with them. The FTIR spectra indicate that the Co atoms interact with the meridional (mer) isomer of Alq(3) rather than forming inorganic compounds.

Sonochemical fabrication of 8-hydroxyquinoline aluminum (Alq3) nanoflowers with high electrogenerated chemiluminescence.

PubMed

Mao, Chang-Jie; Wang, Dan-Chen; Pan, Hong-Cheng; Zhu, Jun-Jie

2011-03-01

Well-defined Alq(3) nanoflowers were fabricated via a facile and fast sonochemical route. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the structure and shape of the as-prepared product. The results showed that the resulting Alq(3) was composed of nanobelts with thickness about 50 nm, average widths of 200 nm, and length up to 10 μm. The Alq(3) nanoflowers exhibited good electrogenerated chemiluminescence behavior. Copyright © 2010 Elsevier B.V. All rights reserved.

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 Central

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

2012-01-01

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

[Susceptibility of enterococci to natural and synthetic iron chelators].

PubMed

Lisiecki, Paweł; Mikucki, Jerzy

2002-01-01

A total of 79 strains of enterococci belonging to 10 species were tested for susceptibility to natural and synthetic iron chelators. All strains produced siderophores. These enterococci were susceptible to three synthetic iron chelators only: 8-hydroxyquinoline, disodium versenate (EDTA) and o-phenanthroline. They were resistant to all other synthetic chelators: ethylenediamine-di(o-hydroxyphenylacetic acid) (EDDHA), nitrilotriacetate, 2,2'-bipiridyl, salicylic acid, 8-hydroxy-5-sulphonic acid and to all natural chelators: ovotransferrine, human apotransferrine, horse apoferritine, desferrioxamine B, ferrichrome and rhodotorulic acid. The relations between susceptibility/resistance, iron assimilation and structure and stability constants of iron chelators were discussed.

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).

Infrared Spectrum and UV-Induced Photochemistry of Matrix-Isolated 5-Hydroxyquinoline.

PubMed

Kuş, Nihal; Sagdinc, Seda; Fausto, Rui

2015-06-18

The structure, infrared spectrum, and photochemistry of 5-hydroxyquinoline (5HQ) were studied by matrix isolation infrared spectroscopy, complemented by theoretical calculations performed at the DFT(B3LYP)/6-311++G(d,p) level of approximation. According to the calculations, the trans conformer of 5HQ (with the OH group pointing to the opposite direction of the pyridine ring of the molecule) is more stable than the cis form (by ∼8.8 kJ mol(-1)). The main factors determining the relative stability of the two conformers were rationalized through natural bond orbital (NBO) and charge density analyses. The compound was trapped in solid nitrogen at 10 K, and its infrared spectra registered and interpreted, showing the sole presence in the matrix of the more stable trans conformer. Broadband in situ UV irradiations (λ ≥ 288 nm and λ ≥ 235 nm) allowed for the observation of different chemical transformations, which started by excitation to the S1 state of 5HQ, followed by homolytic cleavage of the O-H bond, and subsequent reattachment of the H atom to the 5HQ radical to form quinolin-5(6H)-one and quinolin-5(8H)-one. The first of these two quinolinones was found to convert to open-ring isomeric ketenes, especially when irradiation was performed at higher energy, whereas the second is rather stable under the used experimental conditions. As a whole, the observed photochemistry of matrix-isolated 5HQ closely matches those previously reported for phenol and thiophenol. A detailed mechanistic interpretation for the observed photochemical processes is here proposed, which received support from time-dependent DFT calculations.

Molecular mechanics approach for design and conformational studies of macrocyclic ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rohini,; Akbar, Rifat; Kanungo, B. K., E-mail: b.kanungo@gmail.com

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 andmore » 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.« less

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

PubMed

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

2008-02-01

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

Development and validation of an automated enzyme assay for paracetamol (acetaminophen).

PubMed

Morris, H C; Overton, P D; Ramsay, J R; Campbell, R S; Hammond, P M; Atkinson, T; Price, C P

1990-02-28

A rapid, enzymatic assay for serum or plasma paracetamol has been developed with the potential for adaptation to a wide range of clinical analysers. The method involves the action of an amidase enzyme to produce 4-aminophenol from paracetamol, which in turn reacts with 8-hydroxyquinoline in the presence of manganese ions to form a blue dye. Two stable reagents are used and excellent precision is achieved over the drug concentration range 0-2.5 mmol/l. The method, which is complete within 6 min, has been validated using a Monarch centrifugal analyser and shows no significant interference from endogenous serum compounds, drugs or paracetamol metabolites.

Control of Alq3 wetting layer thickness via substrate surface functionalization.

PubMed

Tsoi, Shufen; Szeto, Bryan; Fleischauer, Michael D; Veinot, Jonathan G C; Brett, Michael J

2007-06-05

The effects of substrate surface energy and vapor deposition rate on the initial growth of porous columnar tris(8-hydroxyquinoline)aluminum (Alq3) nanostructures were investigated. Alq3 nanostructures thermally evaporated onto as-supplied Si substrates bearing an oxide were observed to form a solid wetting layer, likely caused by an interfacial energy mismatch between the substrate and Alq3. Wetting layer thickness control is important for potential optoelectronic applications. A dramatic decrease in wetting layer thickness was achieved by depositing Alq3 onto alkyltrichlorosilane-derivatized Si/oxide substrates. Similar effects were noted with increasing deposition rates. These two effects enable tailoring of the wetting layer thickness.

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.

Spectral broadening in electroluminescence of white organic light-emitting diodes based on complementary colors

NASA Astrophysics Data System (ADS)

Kim, Young Min; Park, Young Wook; Choi, Jin Hwan; Ju, Byeong Kwon; Jung, Jae Hoon; Kim, Jai Kyeong

2007-01-01

The authors report the optical and electroluminescent (EL) properties of white organic light-emitting diodes (OLEDs) which have two emitters with similar structures: 1, 1, 4, 4-tetraphenyl-1, 3-butadiene and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline have an emission peak of 400nm around the near ultraviolet, and tris-(8-hydroxyquinoline) aluminum doped with 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran has an emission peak of 580nm producing a yellow color. The EL spectra of the white OLED have shown a broadening through visual range from 400to780nm. This spectral broadening is related to an exciplex emission at the organic solid interface.

Improved performance of organic light-emitting diodes with MoO3 interlayer by oblique angle deposition.

PubMed

Liu, S W; Divayana, Y; Sun, X W; Wang, Y; Leck, K S; Demir, H V

2011-02-28

We fabricated and demonstrated improved organic light emitting diodes (OLEDs) in a thin film architecture of indium tin oxide (ITO)/ molybdenum trioxide (MoO3) (20 nm)/N,N'-Di(naphth-2-yl)-N,N'-diphenyl-benzidine (NPB) (50 nm)/ tris-(8-hydroxyquinoline) (Alq3) (70 nm)/Mg:Ag (200 nm) using an oblique angle deposition technique by which MoO3 was deposited at oblique angles (θ) with respect to the surface normal. It was found that, without sacrificing the power efficiency of the device, the device current efficiency and external quantum efficiency were significantly enhanced at an oblique deposition angle of θ=60° for MoO3.

Effects of morphological control on the characteristics of vertical-type OTFTs using Alq3.

PubMed

Kim, Young Do; Park, Jong Wook; Kang, In Nam; Oh, Se Young

2008-09-01

We have fabricated vertical-type organic thin-film transistors (OTFTs) using tris-(8-hydroxyquinoline) aluminum (Alq(3)) as an n-type active material. Vertical-type OTFT using Alq(3) has a layered structure of Al(source electrode)/Alq(3)(active layer)/Al(gate electrode)/Alq(3)(active layer)/ITO glass(drain electrode). Alq(3) thin films containing various surface morphologies could be obtained by the control of evaporation rate and substrate temperature. The effects of the morphological control of Alq(3) thin layer on the grain size and the flatness of film surface were investigated. The characteristics of vertical-type OTFT significantly influenced the growth condition of Alq(3) layer.

Maximizing the value of gate capacitance in field-effect devices using an organic interface layer

NASA Astrophysics Data System (ADS)

Kwok, H. L.

2015-12-01

Past research has confirmed the existence of negative capacitance in organics such as tris (8-Hydroxyquinoline) Aluminum (Alq3). This work explored using such an organic interface layer to enhance the channel voltage in the field-effect transistor (FET) thereby lowering the sub-threshold swing. In particular, if the values of the positive and negative gate capacitances are approximately equal, the composite negative capacitance will increase by orders of magnitude. One concern is the upper frequency limit (∼100 Hz) over which negative capacitance has been observed. Nonetheless, this frequency limit can be raised to kHz when the organic layer is subjected to a DC bias.

Intrinsic mobility limit for anisotropic electron transport in Alq3.

PubMed

Drew, A J; Pratt, F L; Hoppler, J; Schulz, L; Malik-Kumar, V; Morley, N A; Desai, P; Shakya, P; Kreouzis, T; Gillin, W P; Kim, K W; Dubroka, A; Scheuermann, R

2008-03-21

Muon spin relaxation has been used to probe the charge carrier motion in the molecular conductor Alq3 (tris[8-hydroxy-quinoline] aluminum). At 290 K, the magnetic field dependence of the muon spin relaxation corresponds to that expected for highly anisotropic intermolecular electron hopping. Intermolecular mobility in the fast hopping direction has been found to be 0.23+/-0.03 cm2 V-1 s(-1) in the absence of an electric- field gradient, increasing to 0.32+/-0.06 cm2 V-1 s(-1) in an electric field gradient of 1 MV m(-1). These intrinsic mobility values provide an estimate of the upper limit for mobility achievable in bulk material.

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.

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.

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. Copyright © 2016 Elsevier B.V. All rights reserved.

Monitoring underlying epoxy-coated St-37 corrosion via 8-hydroxyquinoline as a fluorescent indicator

NASA Astrophysics Data System (ADS)

Roshan, Shamim; Sarabi Dariani, Ali Asghar; Mokhtari, Javad

2018-05-01

In the present study, successful performance of 8-hydroxyquinoline (8-HQ) as a ferric ion sensitive indicator is described. 8-HQ was used in epoxy coating because of its desirable properties. It doesn't exhibit premature fluorescence when mixed with coating precursors. Additionally it shows fluorescence turn-on mechanism upon chelate formation with Fe2+/Fe3+ ions produced during anodic reaction. The effect of different concentrations of 8-HQ (0.05, 0.1, 0.5 and 1 wt.%) incorporated in the epoxy coating on corrosion detection as well as optical and electrochemical behavior of the applied coating were studied. The fluorescence property of 8-HQ/Fe3+ solutions was evaluated by using fluorometer. The UV-Visible spectroscopy was used to investigate the effect of 8-HQ presence in the coating on transparency of the free films of the samples. The corrosion detection was performed by fluorescence microscope and the anti-corrosion performance of coated samples containing different concentrations of 8-HQ was studied using salt spray standard test and electrochemical impedance spectroscopy (EIS). The results of UV-Visible spectroscopy demonstrated that increasing 8-HQ concentration causes a slight decrease in coating transparency. According to the results of electrochemical impedance spectroscopy (EIS) measurements, the polarization resistance of the coated St-37 sample containing 0.1 wt.% 8-HQ was about 109 Ohm cm2 after 6 weeks immersion in corrosive electrolyte, while St-37 plates coated with other 8-HQ concentrations showed decreased resistance levels of about 106 Ohm cm2, during the same immersion period. Based on fluorescence microscopic investigation, as a result of incorporating 8-HQ into the epoxy matrix, fluorescence could be observed in regions where Fe2+/Fe3+ ions were produced through anodic reactions. This method is capable of detecting corrosion in situ at early stages before the metal surface suffers serious damages.

Flame atomic absorption spectrometric determination of heavy metals in aqueous solution and surface water preceded by co-precipitation procedure with copper(II) 8-hydroxyquinoline

NASA Astrophysics Data System (ADS)

Ipeaiyeda, Ayodele Rotimi; Ayoade, Abisayo Ruth

2017-12-01

Co-precipitation procedure has widely been employed for preconcentration and separation of metal ions from the matrices of environmental samples. This is simply due to its simplicity, low consumption of separating solvent and short duration for analysis. Various organic ligands have been used for this purpose. However, there is dearth of information on the application of 8-hydroxyquinoline (8-HQ) as ligand and Cu(II) as carrier element. The use of Cu(II) is desirable because there is no contamination and background adsorption interference. Therefore, the objective of this study was to use 8-HQ in the presence of Cu(II) for coprecipitation of Cd(II), Co(II), Cr(III), Ni(II) and Pb(II) from standard solutions and surface water prior to their determinations by flame atomic absorption spectrometry (FAAS). The effects of pH, sample volume, amount of 8-HQ and Cu(II) and interfering ions on the recoveries of metal ions from standard solutions were monitored using FAAS. The water samples were treated with 8-HQ under the optimum experimental conditions and metal concentrations were determined by FAAS. The metal concentrations in water samples not treated with 8-HQ were also determined. The optimum recovery values for metal ions were higher than 85.0%. The concentrations (mg/L) of Co(II), Ni(II), Cr(III), and Pb(II) in water samples treated with 8-HQ were 0.014 ± 0.002, 0.03 ± 0.01, 0.04 ± 0.02 and 0.05 ± 0.02, respectively. These concentrations and those obtained without coprecipitation technique were significantly different. Coprecipitation procedure using 8-HQ as ligand and Cu(II) as carrier element enhanced the preconcentration and separation of metal ions from the matrix of water sample.

Real-space identification of intermolecular bonding with atomic force microscopy.

PubMed

Zhang, Jun; Chen, Pengcheng; Yuan, Bingkai; Ji, Wei; Cheng, Zhihai; Qiu, Xiaohui

2013-11-01

We report a real-space visualization of the formation of hydrogen bonding in 8-hydroxyquinoline (8-hq) molecular assemblies on a Cu(111) substrate, using noncontact atomic force microscopy (NC-AFM). The atomically resolved molecular structures enable a precise determination of the characteristics of hydrogen bonding networks, including the bonding sites, orientations, and lengths. The observation of bond contrast was interpreted by ab initio density functional calculations, which indicated the electron density contribution from the hybridized electronic state of the hydrogen bond. Intermolecular coordination between the dehydrogenated 8-hq and Cu adatoms was also revealed by the submolecular resolution AFM characterization. The direct identification of local bonding configurations by NC-AFM would facilitate detailed investigations of intermolecular interactions in complex molecules with multiple active sites.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Alex J.; Sakai, Yuki; Kim, Minjung

2016-05-09

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 frommore » repulsive tip tilting induced by neighboring electron-rich atoms.« less

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

NASA Astrophysics Data System (ADS)

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

2016-02-01

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

Electron Transport in Paracoccus Halodenitrificans and the Role of Ubiquinone

NASA Technical Reports Server (NTRS)

Hochstein, L. I.; Cronin, S. E.

1983-01-01

The membrane-bound NADH oxidase of Paracoccus halodenitrificans was inhibited by dicoumarol, 2-n-heptyl-4-hydroxyquinoline-N-oxide (HQNO), and exposure to ultraviolet light (at 366 nm). When the membranes were extracted with n-pentane, NADH oxidase activity was lost. Partial restoration was achieved by adding the ubiquinone fraction extracted from the membranes. Succinate oxidation was not inhibited by dicoumarol or HQNO but was affected by ultraviolet irradiation or n-pentane extraction. However, the addition of the ubiquinone fraction to the n-pentane-extracted membranes did not restore enzyme activity. These observations suggested the reducing equivalents from succinate entered the respiratory chain on the oxygen side of the HQNO-sensitive site and probably did not proceed through a quinone.

Electron transport in Paracoccus halodenitrificans and the role of Ubiquinone

NASA Technical Reports Server (NTRS)

Hochstein, L. I.; Cronin, S. E.

1984-01-01

The membrane-bound NADH oxidase of Paracoccus halodenitrificans was inhibited by dicoumarol, 2-n-heptyl-4-hydroxyquinoline-N-oxide (HQNO), and exposure to ultraviolet light (at 366 nm). When the membranes were extracted with n-pentane, NADH oxidase activity was lost. Partial restoration was achieved by adding the ubiquinone fraction extracted from the membranes. Succinate oxidation was not inhibited by dicoumarol or HQNO but was affected by ultraviolet irradiation or n-pentane extraction. However, the addition of the ubiquinone fraction to the n-pentane-extracted membranes did not restore enzyme activity. These observations suggested the reducing equivalents from succinate entered the respiratory chain on the oxygen side of the HQNO-sensitive site and probably did not proceed through a quinone.

Tunable electroluminescent color for 2, 5-diphenyl -1, 4-distyrylbenzene with two trans-double bonds

NASA Astrophysics Data System (ADS)

Cheng, Gang; Zhang, Yingfang; Zhao, Yi; Liu, Shiyong; Xie, Zengqi; Xia, Hong; Hanif, Muddasir; Ma, Yuguang

2005-07-01

Exciplex emission is observed in electroluminescent (EL) spectrum of an organic light-emitting device (OLED), where 2, 5-diphenyl -1, 4-distyrylbenzene with two trans-double bonds (trans-DPDSB), (8-hydroxyquinoline) aluminum, and N,N'-diphenyl-N,N'-bis(1-naphthyl)-(1,1'-biphenyl)-4,4'-diamine (NPB) are used as light-emitting, electron-transporting, and hole-transporting layers, respectively. This emission can be dramatically weakened by inserting a hole-injecting layer of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) between the hole-transporting layer and the anode. Consequently, EL color of this OLED is tuned from white to blue. This phenomenon may result from the improvement of hole injection, which shifts the major recombination zone from the NPB/trans-DPDSB interface to the trans-DPDSB layer.

Site-directed mutagenesis of conserved cysteine residues in NqrD and NqrE subunits of Na+-translocating NADH:quinone oxidoreductase.

PubMed

Fadeeva, M S; Bertsova, Y V; Verkhovsky, M I; Bogachev, A V

2008-02-01

Each of two hydrophobic subunits of Na+-translocating NADH:quinone oxidoreductase (NQR), NqrD and NqrE, contain a pair of strictly conserved cysteine residues within their transmembrane alpha-helices. Site-directed mutagenesis showed that substitutions of these residues in NQR of Vibrio harveyi blocked the Na+-dependent and 2-n-heptyl-4-hydroxyquinoline N-oxide-sensitive quinone reductase activity of the enzyme. However, these mutations did not affect the interaction of NQR with NADH and menadione. It was demonstrated that these conserved cysteine residues are necessary for the correct folding and/or the stability of the NQR complex. Mass and EPR spectroscopy showed that NQR from V. harveyi bears only a 2Fe-2S cluster as a metal-containing prosthetic group.

Effects of interfacial stability between electron transporting layer and cathode on the degradation process of organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Chu, Ta-Ya; Lee, Yong-Han; Song, Ok-Keun

2007-11-01

The authors have demonstrated that the increase of electron injection barrier height between tris(8-hydroxyquinoline)aluminum (Alq3) and LiF /Al cathode is one of the most critical parameters to determine the reliability of organic light-emitting diode with the typical structure of indium tin oxide/N ,N'-bis(naphthalen-1-yl)-N ,N'-bis(phenyl) benzidine/Alq3/LiF /Al. The electrical properties of several devices (hole only, electron only, and integrated double-layered devices) have been measured in the function of operating time to analyze the bulk and interface property changes. Bulk properties of trap energy and mobility in an organic layer have been estimated by using trap-charge-limited currents and transient electroluminescence measurements.

Thermometric titration studies of mixed ligand complexes of thorium.

PubMed

Kugler, G C; Carey, G H

1970-10-01

Mixed-ligand chelates consisting of two different multidentate ligands linked to a central thorium(IV) ion have been prepared in aqueous solution and their heats of formation studied thermo metrically. Pyrocatechol, tiron, chromotropic acid, potassium hydrogen phthalate, 8-hydroxyquinoline-S-sulphonic acid, iminodiacetic acid, 5-sulphosalicylic acid and salicylic acid were used as the secondary ligands, while ethylenediaminetetra-acetate and 1, 2-diaminocyclohexane-N,N,N',N'-tetra-acetate were used as primary ligands. DeltaH values for the overall reactions are given, and where possible, the DeltaH and DeltaS values for the specific secondary ligand addition were calculated. The overall stability of the mixed-ligand chelates and the enhanced stability of EDTA mixed chelates relative to the analogous DCTA chelates were found to be due to entropy rather than enthalpy effects.

Controlled Self-Assembly of Low-Dimensional Alq3 Nanostructures from 1D Nanowires to 2D Plates via Intermolecular Interactions

NASA Astrophysics Data System (ADS)

Gu, Jianmin; Yin, Baipeng; Fu, Shaoyan; Jin, Cuihong; Liu, Xin; Bian, Zhenpan; Li, Jianjun; Wang, Lu; Li, Xiaoyu

2018-03-01

Due to the intense influence of the shape and size of the photon building blocks on the limitation and guidance of optical waves, an important strategy is the fabrication of different structures. Herein, organic semiconductor tris-(8-hydroxyquinoline)aluminium (Alq3) nanostructures with controllable morphology, ranging from one-dimensional nanowires to two-dimensional plates, have been prepared through altering intermolecular interactions with employing the anti-solvent diffusion cooperate with solvent-volatilization induced self-assembly method. The morphologies of the formed nanostructures, which are closely related to the stacking modes of the molecules, can be exactly controlled by altering the polarity of anti-solvents that can influence various intermolecular interactions. The synthesis strategy reported here can potentially be extended to other functional organic nanomaterials.

High performance organic ultraviolet photodetectors based on m-MTDATA

NASA Astrophysics Data System (ADS)

Zhao, Zhongli; Bai, Xiaofeng; Shang, Yubin; Yang, Jikai; Li, Baozeng; Song, De

2018-02-01

We demonstrate highly efficient organic ultraviolet photodetectors using 4,4',4'' -tris[3-methyl-pheny(phenyl) amino] triphenylamine (m-MTDATA) and aluminum Tris(8-Hydroxyquinolinate) Synonym Alq3). The optimized photodetector delivers a photocurrent of 1.40 mA/cm2 at10 V, corresponding to a response of 127 mA/W under an illumination of 375 nm UV light irradiation with an intensity of 10.5 mW/cm2 and a detectivity of 2.15×1011 cm Hz1/2 /W. The high response is attributed to the larger band offset at m-MTDATA/ Alq3 heterojunction, the suppression of radiative decay of m-MTDATA and efficient electron transfer from m-MTDATA to Alq3. The working mechanism of harvesting high performance is also discussed in detail.

Vibrational spectroscopic studies of an organic non-linear optical crystal 8-hydroxyquinolinium picrate

NASA Astrophysics Data System (ADS)

Krishna Kumar, V.; Nagalakshmi, R.

2007-04-01

8-Hydroxyquinolinium picrate (8-HQP) was synthesized by the addition of equimolar quantities of 8-hydroxyquinoline (8-HQ) and picric acid (PA). Single crystals were grown from N, N dimethyl formamide (DMF) by restricted evaporation method at room temperature. The solubility of 8-HQP was determined in different solvents at various temperatures. The structural characterization of the grown crystals was carried out by X-ray diffraction. Vibrational modes were classified on the basis of group theoretical analysis and the spectral bands were compared with those of parent compounds in order to propose a tentative assignment by recording FT-IR, FT-Raman and polarized Raman spectra in different crystal orientations. The crystal possess lower cut-off at 230 nm and good transparency as confirmed by optical transmittance studies.

Enzymatic properties of the membrane-bound NADH oxidase system in the aerobic respiratory chain of Bacillus cereus.

PubMed

Kim, Man Suk; Kim, Young Jae

2004-11-30

Membranes prepared from Bacillus cereus KCTC 3674, grown aerobically on a complex medium, oxidized NADH exclusively, whereas deamino-NADH was little oxidized. The respiratory chain-linked NADH oxidase exhibited an apparent K(m) value of approximately 65 microM for NADH. The maximum activity of the NADH oxidase was obtained at about pH 8.5 in the presence of 0.1 M KCl (or NaCl). Respiratory chain inhibitor 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) inhibited the activity of the NADH oxidase by about 90% at a concentration of 40 microM. Interestingly, rotenone and capsaicin inhibited the activity of the NADH oxidase by about 60% at a concentration of 40 microM and the activity was also highly sensitive to Ag(+).

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.

Hepatocyte or serum albumin protein carbonylation by oxidized fructose metabolites: Glyceraldehyde or glycolaldehyde as endogenous toxins?

PubMed

Dong, Qiang; Yang, Kai; Wong, Stephanie M; O'Brien, Peter J

2010-10-06

Excessive sugar intake in animal models may cause tissue damage associated with oxidative and carbonyl stress cytotoxicity as well as inflammation. Fructose became a 100-fold more cytotoxic if hepatocytes were exposed to a non-toxic infusion of H(2)O(2) so as to simulate H(2)O(2) released by Kupffer cells or infiltrating immune cells. In order to determine the molecular mechanisms involved, protein carbonylation of fructose and its metabolites were determined using the 2,4-dinitrophenylhydrazine method. In a cell-free system, fructose was found to carbonylate bovine serum albumin (BSA) only if low concentrations of FeII/H(2)O(2) were added. Protein carbonylation by the fructose metabolites glyceraldehyde or glycolaldehyde was also markedly increased by FeII/H(2)O(2). The protein carbonylation may be attributed to glyoxal formation by hydroxyl radicals as the glyoxal trapping agent aminoguanidine or hydroxyl radical scavengers prevented protein carbonylation. Glyoxal was also much more effective than other carbonyls at causing protein carbonylation. When BSA was replaced by isolated rat hepatocytes, fructose metabolite glyceraldehyde in the presence of non-toxic 2 microM FeII:8-hydroxyquinoline (HQ) and a H(2)O(2) generating system (glucose/glucose oxidase) markedly increased cytotoxicity, protein carbonylation and reactive oxygen species (ROS)/H(2)O(2) formation. Furthermore this was prevented by hydroxyl radical scavengers or aminoguanidine, a glyoxal scavenger. CuII: 8-hydroxyquinoline increased H(2)O(2) induced hepatocyte protein carbonylation less but was prevented by aminoguanidine. However, cytotoxicity and protein carbonylation induced by glyceraldehyde/CuII:HQ/H(2)O(2) were not affected by hydroxyl radical scavengers. Although fatty liver induced by an excessive sugar diet in animal models has been proposed as the first hit for non-alcoholic steatohepatitis (NASH) we propose that oxidative stress induced by the oxidation of fructose or fructose metabolites catalysed by Fenton FeII/H(2)O(2) could be a 'second hit'. A perpetual cycle of oxidative stress in hepatocytes could lead to cytotoxicity and contribute to NASH development. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

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

PubMed

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

2015-05-05

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 studies. Copyright © 2015 Elsevier B.V. All rights reserved.

In vivo distribution of human milk leucocytes after ingestion by newborn baboons.

PubMed Central

Jain, L; Vidyasagar, D; Xanthou, M; Ghai, V; Shimada, S; Blend, M

1989-01-01

The in vivo distribution of enterally administered human milk leucocytes labelled with indium hydroxyquinoline (111In) was studied in premature baboons. The animals were killed at 72 hours of age and tissue samples examined for radioactivity. Maximum activity was found in the luminal contents, and activity in the liver and spleen was higher than in bone marrow, the site where free isotope is normally deposited. These findings suggest that some intact milk leucocytes may cross from the gastrointestinal tract into the neonatal circulation. Also the high activity in gastrointestinal tissue that had been washed several times indicates that leucocytes adhere to mucosa or lie intramurally. We speculate that the presence of leucocytes in the gastrointestinal tract 60 hours after a single breast feed can provide an important defence mechanism against infection. PMID:2774634

Cloud point extraction: an alternative to traditional liquid-liquid extraction for lanthanides(III) separation.

PubMed

Favre-Réguillon, Alain; Draye, Micheline; Lebuzit, Gérard; Thomas, Sylvie; Foos, Jacques; Cote, Gérard; Guy, Alain

2004-06-17

Cloud point extraction (CPE) was used to extract and separate lanthanum(III) and gadolinium(III) nitrate from an aqueous solution. The methodology used is based on the formation of lanthanide(III)-8-hydroxyquinoline (8-HQ) complexes soluble in a micellar phase of non-ionic surfactant. The lanthanide(III) complexes are then extracted into the surfactant-rich phase at a temperature above the cloud point temperature (CPT). The structure of the non-ionic surfactant, and the chelating agent-metal molar ratio are identified as factors determining the extraction efficiency and selectivity. In an aqueous solution containing equimolar concentrations of La(III) and Gd(III), extraction efficiency for Gd(III) can reach 96% with a Gd(III)/La(III) selectivity higher than 30 using Triton X-114. Under those conditions, a Gd(III) decontamination factor of 50 is obtained.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Sijie; Gillin, W. P., E-mail: w.gillin@qmul.ac.uk; Materials Research Institute and School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS

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 aluminiummore » 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.« less

Respiration-linked proton translocation coupled to anaerobic reduction of manganese(IV) and iron(III) in Shewanella putrefaciens MR-1.

PubMed Central

Myers, C R; Nealson, K H

1990-01-01

An oxidant pulse technique, with lactate as the electron donor, was used to study respiration-linked proton translocation in the manganese- and iron-reducing bacterium Shewanella putrefaciens MR-1. Cells grown anaerobically with fumarate or nitrate as the electron acceptor translocated protons in response to manganese (IV), fumarate, or oxygen. Cells grown anaerobically with fumarate also translocated protons in response to iron(III) and thiosulfate, whereas those grown with nitrate did not. Aerobically grown cells translocated protons only in response to oxygen. Proton translocation with all electron acceptors was abolished in the presence of the protonophore carbonyl cyanide m-chlorophenylhydrazone (20 microM) and was partially to completely inhibited by the electron transport inhibitor 2-n-heptyl-4-hydroxyquinoline N-oxide (50 microM). PMID:2172208

Vacuum-deposited, nonpolymeric flexible organic light-emitting devices.

PubMed

Gu, G; Burrows, P E; Venkatesh, S; Forrest, S R; Thompson, M E

1997-02-01

We demonstrate mechanically flexible, organic light-emitting devices (OLED's) based on the nonpolymetric thin-film materials tris-(8-hydroxyquinoline) aluminum (Alq(3)) and N, N(?) -diphenyl- N, N(?) -bis(3-methylphenyl)1- 1(?) biphenyl-4, 4(?) diamine (TPD). The single heterostructure is vacuum deposited upon a transparent, lightweight, thin plastic substrate precoated with a transparent, conducting indium tin oxide thin film. The flexible OLED performance is comparable with that of conventional OLED's deposited upon glass substrates and does not deteriorate after repeated bending. The large-area (~1 - cm>(2)) devices can be bent without failure even after a permanent fold occurs if they are on the convex substrate surface or over a bend radius of ~0.5>cm if they are on the concave surface. Such devices are useful for ultralightweight, flexible, and comfortable full-color flat panel displays.

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).

Bio-recognitive photonics of a DNA-guided organic semiconductor

PubMed Central

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riku, C.; Kee, Y. Y.; Ong, T. 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 employedmore » to compute the current density-applied voltage-luminance characteristics, distribution of the electric field, carrier concentrations and recombination rate.« less

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.

Tandem organic light-emitting diodes with KBH4 doped 9,10-bis(3-(pyridin-3-yl)phenyl) anthracene connected to the charge generation layer.

PubMed

Duan, Lian; Tsuboi, Taiju; Qiu, Yong; Li, Yanrui; Zhang, Guohui

2012-06-18

Tandem organic light emitting diodes (OLEDs) are ideal for lighting applications due to their low working current density at high brightness. In this work, we have studied an efficient electron transporting layer of KBH(4) doped 9,10-bis(3-(pyridin-3-yl)phenyl)anthracene (DPyPA) which is located adjacent to charge generation layer of MoO(3)/NPB. The excellent transporting property of the DPyPA:KBH(4) layer helps the tandem OLED to achieve a lower voltage than the tandem device with the widely used tris-(8-hydroxyquinoline)aluminum:Li. For the tandem white OLED with a fluorescent blue unit and a phosphorescent yellow unit, we've achieved a high current efficiency of 75 cd/A, which can be further improved to 120 cd/A by attaching a diffuser layer.

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

PubMed

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

2013-01-01

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

Low intrinsic carrier density LSMO/Alq3/AlOx/Co organic spintronic devices

NASA Astrophysics Data System (ADS)

Riminucci, Alberto; Graziosi, Patrizio; Calbucci, Marco; Cecchini, Raimondo; Prezioso, Mirko; Borgatti, Francesco; Bergenti, Ilaria; Dediu, Valentin Alek

2018-04-01

The understanding of spin injection and transport in organic spintronic devices is still incomplete, with some experiments showing magnetoresistance and others not detecting it. We have investigated the transport properties of a large number of tris-(8-hydroxyquinoline)aluminum-based organic spintronic devices with an electrical resistance greater than 5 MΩ that did not show magnetoresistance. Their transport properties could be described satisfactorily by known models for organic semiconductors. At high voltages (>2 V), the results followed the model of space charge limited current with a Poole-Frenkel mobility. At low voltages (˜0.1 V), that are those at which the spin valve behavior is usually observed, the charge transport was modelled by nearest neighbor hopping in intra-gap impurity levels, with a charge carrier density of n0 = (1.44 ± 0.21) × 1015 cm-3 at room temperature. Such a low carrier density can explain why no magnetoresistance was observed.

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

PubMed

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

2016-01-04

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.

ON THE RELATIVE STABILITY OF ALUMINUM, TITANIUM, VANADIUM, IRON, AND COPPER TARTRATE COMPLEXES IN ALKALI MEDIA (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pyatnitskii, I.V.; Kostyshina, A.P.

1959-06-01

The stability of aluminum, copper, iron, titunium, and vanadium tartrate complexes was determined using bond magnitudes as criteria (the ratio between the concentrations of complexed and free ions at a certain standard acid condition). A method is suggested for determining the ratio of the bonds combining the complexes of two metals. The partition constaats of aluminum, copper, iron(III), and vanadium hydroxyquinolinates between the aqueous solution and chloroform were 2.6 x 10/sup -33/, 7.3 x 10/sup -23/, 1.5 x 10/sup -37/, and 4.2 x 10/sup -23/, respectively. The relative stability of copper and iron turtrate complexes in alkali solution (pH 13)more » and aluminum, iron(III), titunium, and vanadium(IV) tartrate complexes in ammonium solution (pH 9.5) was determined. (R.V.J.)« less

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.

Microscopic Simulations of Charge Transport in Disordered Organic Semiconductors

PubMed Central

2011-01-01

Charge carrier dynamics in an organic semiconductor can often be described in terms of charge hopping between localized states. The hopping rates depend on electronic coupling elements, reorganization energies, and driving forces, which vary as a function of position and orientation of the molecules. The exact evaluation of these contributions in a molecular assembly is computationally prohibitive. Various, often semiempirical, approximations are employed instead. In this work, we review some of these approaches and introduce a software toolkit which implements them. The purpose of the toolkit is to simplify the workflow for charge transport simulations, provide a uniform error control for the methods and a flexible platform for their development, and eventually allow in silico prescreening of organic semiconductors for specific applications. All implemented methods are illustrated by studying charge transport in amorphous films of tris-(8-hydroxyquinoline)aluminum, a common organic semiconductor. PMID:22076120

Organic bistable memory devices based on MoO3 nanoparticle embedded Alq3 structures.

PubMed

Abhijith, T; Kumar, T V Arun; Reddy, V S

2017-03-03

Organic bistable memory devices were fabricated by embedding a thin layer of molybdenum trioxide (MoO 3 ) between two tris-(8-hydroxyquinoline)aluminum (Alq 3 ) layers. The device exhibited excellent switching characteristics with an ON/OFF current ratio of 1.15 × 10 3 at a read voltage of 1 V. The device showed repeatable write-erase capability and good stability in both the conductance states. These conductance states are non-volatile in nature and can be obtained by applying appropriate voltage pulses. The effect of MoO 3 layer thickness and its location in the Alq 3 matrix on characteristics of the memory device was investigated. The field emission scanning electron microscopy (FE-SEM) images of the MoO 3 layer revealed the presence of isolated nanoparticles. Based on the experimental results, a mechanism has been proposed for explaining the conductance switching of fabricated devices.

Surface morphology and interdiffusion of LiF in Alq3-based organic light-emitting devices.

PubMed

Lee, Young Joo; Li, Xiaolong; Kang, Da-Yeon; Park, Seong-Sik; Kim, Jinwoo; Choi, Jeong-Woo; Kim, Hyunjung

2008-09-01

Highly efficient organic light-emitting devices (OLEDs) have been realized by insertion of a thin insulating lithium fluoride (LiF) layer between aluminum (Al) cathode and an electron transport layer, tris-(8-hydroxyquinoline) aluminum (Alq(3)). In this paper, we study the surface morphology of LiF on Alq(3) by synchrotron X-ray scattering and atomic force microscopy (AFM) as a function of thickness of LiF. We also study the interdiffusion of LiF into Al cathode as well as into Alq(3) layer as a function of temperature. Initially, LiF molecules are distributed randomly as clusters on the Alq(3) layer and then gradually form a layer as increasing LiF thickness. The interdiffusion of LiF into Al occurs more actively than into Alq(3) in annealing process. LiF on Alq(3) induces the ordering of Al to (111) direction strongly with increasing LiF thickness.

[Optical and morphological investigation on the interaction of dual dopants in poly (N-vinylcarzole)].

PubMed

Zhang, Ting; Xu, Zheng; Teng, Feng; Qian, Lei; Wang, Yong-Sheng; Xu, Xu-Rong

2006-05-01

The effect of optical and electrical properties of poly(N-vinylcarzole) (PVK) doped with two dyes, i. e. 8-tris-hydroxyquinoline (Alq3) and 4-(dicyanomethylene)-2-tert-butyl-6 (1, 1, 7, 7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB), on the energy transfer and charge trapping processes was investigated. The phase separation in blends film at different doping concentration was also studied. More homogeneous dispersion of dyes in PVK with increasing doping concentration was showed. The results indicate that there is a certain interaction of Alq3 and DCJTB in this dual-doped system. It is the incorporation of DCJTB that untangled the aggregation of Alq3 owing to the interaction of DCJTB and Alq3. But for higher doping concentration, DCJTB results in an isolated charge transport channel that decreases the electroluminescence (EL) operating voltage.

Manipulating Refractive Index in Organic Light-Emitting Diodes.

PubMed

Salehi, Amin; Chen, Ying; Fu, Xiangyu; Peng, Cheng; So, Franky

2018-03-21

In a conventional organic light-emitting diode (OLED), only a fraction of light can escape to the glass substrate and air. Most radiation is lost to two major channels: waveguide modes and surface plasmon polaritons. It is known that reducing the refractive indices of the constituent layers in an OLED can enhance light extraction. Among all of the layers, the refractive index of the electron transport layer (ETL) has the largest impact on light extraction because it is the layer adjacent to the metallic cathode. Oblique angle deposition (OAD) provides a way to manipulate the refractive index of a thin film by creating an ordered columnar void structure. In this work, using OAD, the refractive index of tris(8-hydroxyquinoline)aluminum (Alq3) can be tuned from 1.75 to 1.45. With this low-index ETL deposited by OAD, the resulting phosphorescent OLED shows nearly 30% increase in light extraction efficiency.

Arsenic species analysis in porewaters and sediments using hydride generation atomic fluorescence spectrometry.

PubMed

Liao, Meng-xia; Deng, Tian-long

2006-01-01

It was observed that the atomic fluorescence emission due to As(V) could has a 10% to 40% of fluorescence emission signal during the determination of As(III) in the mixture of As(III) and As(V). Besides, interferes from heavy metals such as Pb(lIl), Cu(ll) can cause severe increase of the signals as compared to the insignificant effects caused by Cd(II), Zn(ll), Mn(II) and Fe(Ill). On the basis of further studies, the masking agent of 8-hydroxyquinoline was used as an efficient agent to eliminate interference of As(V) emission and the heavy metal of Cu2+ and Pb2+ in the measurements of arsenic species. After a series standard additions and CRM researches, a sensitive and interference-free analytical procedure was developed for the speciation of arsenic in samples of porewaters and sediments in Poyang Lake, China.

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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]styrylbenzene (DSA-Ph) in mixtures with aluminum-tris(8-hydroxyquinoline) (Alq 3) by spectroscopic ellipsometry and IR dichroism. We find that molecular orientation is controlled by the ratio of the substrate temperature during deposition and the glassmore » transition temperature of the mixture. Furthermore, 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.« less

Organic bistable memory devices based on MoO3 nanoparticle embedded Alq3 structures

NASA Astrophysics Data System (ADS)

Abhijith, T.; Kumar, T. V. Arun; Reddy, V. S.

2017-03-01

Organic bistable memory devices were fabricated by embedding a thin layer of molybdenum trioxide (MoO3) between two tris-(8-hydroxyquinoline)aluminum (Alq3) layers. The device exhibited excellent switching characteristics with an ON/OFF current ratio of 1.15 × 103 at a read voltage of 1 V. The device showed repeatable write-erase capability and good stability in both the conductance states. These conductance states are non-volatile in nature and can be obtained by applying appropriate voltage pulses. The effect of MoO3 layer thickness and its location in the Alq3 matrix on characteristics of the memory device was investigated. The field emission scanning electron microscopy (FE-SEM) images of the MoO3 layer revealed the presence of isolated nanoparticles. Based on the experimental results, a mechanism has been proposed for explaining the conductance switching of fabricated devices.

Synthesis and characterization of organic/inorganic heterostructure films for hybrid light emitting diode

NASA Astrophysics Data System (ADS)

Toyama, Toshihiko; Ichihara, Tokuyuki; Yamaguchi, Daisuke; Okamoto, Hiroaki

2007-10-01

Thin-film light emitting devices based on organic materials have been gathering attentions for applying a flat-panel display and a solid-state lighting. Alternatively, inorganic technologies such as Si-based thin-film technology have been growing almost independently. It is then expected that combining the Si-based thin-film technology with the organic light emitting diode (OLED) technology will develop innovative devices. Here, we report syntheses of the hybrid light emitting diode (LED) with a heterostructure consisting of p-type SiC x and tris-(8-hydroxyquinoline) aluminum films and characterization for the hybrid LEDs. We present the energy diagram of the heterostructure, and describe that the use of high dark conductivities of the p-type SiC x as well as inserting wide-gap intrinsic a-SiC x at the p-type SiC x/Alq interface are effective for improving device performance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marousky, F.J.; Woltz, S.S.

The influence of soluble fluoride and a floral preservative (600 ppm 8-hydroxyquinoline citrate + 4% sucrose) on floret opening and quality of cut gladiolus was investigated using several cultivars. All cultivars evaluated showed distinct petal margin deterioration and necrosis at 1 ppm F. Many cultivars showed distinct petal margin discoloration and deterioration with accompanying bract and leaf margin deterioration in 4 days at 0.25 ppm fluoride. Colored flowering cultivars showed more fluoride injury than white or yellow flowering cultivars. Petal margin deterioration was most severe when spikes were continuously exposed to water containing fluoride. Florets on Victory spikes held inmore » water containing fluoride did not open as fully as those on spikes held in water. Floral preservative increased the number of open flowers and sustained floret quality. However, the preservative did not overcome the deleterious effects of fluoride in vase water. 13 references, 2 figures, 4 tables.« less

Plastic lab-on-a-chip for fluorescence excitation with integrated organic semiconductor lasers.

PubMed

Vannahme, Christoph; Klinkhammer, Sönke; Lemmer, Uli; Mappes, Timo

2011-04-25

Laser light excitation of fluorescent markers offers highly sensitive and specific analysis for bio-medical or chemical analysis. To profit from these advantages for applications in the field or at the point-of-care, a plastic lab-on-a-chip with integrated organic semiconductor lasers is presented here. First order distributed feedback lasers based on the organic semiconductor tris(8-hydroxyquinoline) aluminum (Alq3) doped with the laser dye 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyril)-4H-pyrane (DCM), deep ultraviolet induced waveguides, and a nanostructured microfluidic channel are integrated into a poly(methyl methacrylate) (PMMA) substrate. A simple and parallel fabrication process is used comprising thermal imprint, DUV exposure, evaporation of the laser material, and sealing by thermal bonding. The excitation of two fluorescent marker model systems including labeled antibodies with light emitted by integrated lasers is demonstrated.

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.

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 intensity in metal complexes with 8-HQS by inhibiting ligand exchange using surfactant complexation for applications in either sensing or optoelectronics.

[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, and from 100.42% to 103.01% by ICP-OES determination for Li. The recovery ranged from 95.91% to 99.98% by FAAS determination for Ag, and ranged from 98.04% to 99.98% for FAAS determination of Li. The recovery was from 98.00% to 101.00 by VS determination for Ag, the analysis results all meet the analysis requirement.

Kinetics of transient electroluminescence in organic light emitting diodes

NASA Astrophysics Data System (ADS)

Shukla, Manju; Kumar, Pankaj; Chand, Suresh; Brahme, Nameeta; Kher, R. S.; Khokhar, M. S. K.

2008-08-01

Mathematical simulation on the rise and decay kinetics of transient electroluminescence (EL) in organic light emitting diodes (OLEDs) is presented. The transient EL is studied with respect to a step voltage pulse. While rising, for lower values of time, the EL intensity shows a quadratic dependence on (t - tdel), where tdel is the time delay observed in the onset of EL, and finally attains saturation at a sufficiently large time. When the applied voltage is switched off, the initial EL decay shows an exponential dependence on (t - tdec), where tdec is the time when the voltage is switched off. The simulated results are compared with the transient EL performance of a bilayer OLED based on small molecular bis(2-methyl 8-hydroxyquinoline)(triphenyl siloxy) aluminium (SAlq). Transient EL studies have been carried out at different voltage pulse amplitudes. The simulated results show good agreement with experimental data. Using these simulated results the lifetime of the excitons in SAlq has also been calculated.

Highly efficient organic electroluminescent diodes realized by efficient charge balance with optimized electron and hole transport layers

NASA Astrophysics Data System (ADS)

Khan, M. A.; Xu, Wei; Wei, Fuxiang; Bai, Yu; Jiang, X. Y.; Zhang, Z. L.; Zhu, W. Q.

2007-11-01

Highly efficient organic electroluminescent devices (OLEDs) were developed based on 4,7-diphenyl-1, 10-phenanthroline (BPhen) as the electron transport layer (ETL), tris-(8-hydroxyquinoline) aluminum (Alq 3) as the emission layer (EML) and N,Ń-bis-[1-naphthy(-N,Ńdiphenyl-1,1'-biphenyl-4,4'-diamine)] (NPB) as the hole transport layer (HTL). The typical device structure was glass substrate/ ITO/ NPB/ Alq 3/ BPhen/ LiF/ Al. Since BPhen possesses a considerable high electron mobility of 5×10 -4 cm 2 V -1 s -1, devices with BPhen as ETL can realize an extremely high luminous efficiency. By optimizing the thickness of both HTL and ETL, we obtained a highly efficient OLED with a current efficiency of 6.80 cd/A and luminance of 1361 cd/m 2 at a current density of 20 mA/cm 2. This dramatic improvement in the current efficiency has been explained on the principle of charge balance.

pH-sensitive fluorescent sensors based on europium(III) complexes.

PubMed

Zhang, Xiaolin; Jiao, Yang; Jing, Xu; Wu, Hongmei; He, Guangjie; Duan, Chunying

2011-03-21

New europium(III) complexes Eu(TTA)(2)-DSQ and Eu(TTA)(3)-DR1 were designed and synthesized as new fluorescent pH probes (where HDSQ = 5-(dimethylamino)-N-(4-(2-((8-hydroxyquinolin-2-yl)methylene)hydrazinecarbonyl)phenyl)naphthalene-1-sulfonamide, DR1 = N(1)-(4-(dimethylamino)benzylidene)-N(2)-(rhodamine-6G) lactamethylene-diamine and TTA = thiophentrifluoroacetone). Eu(TTA)(2)-DSQ exhibited high sensitivity in monitoring pH changes in neutral aqueous solution with negligible background fluorescence. Eu(TTA)(3)-DR1 comprised a green light emitting Rhodamine 6G fluorophore and a Eu(III) moiety as the origin of red light. These pH-sensitive emitter components have pK(a) values of 5.0 and 7.2 respectively, and exhibit isolated protonated steps within one molecule. Luminescence titrations demonstrate that Eu(TTA)(3)-DR1 was able to detect pH values at both near neutral pH and acidic pH ranges, and was also able to detect pH in both cultured cells and in vivo.

Photophysics of a coumarin based Schiff base in solvents of varying polarities

NASA Astrophysics Data System (ADS)

Ghosh, Saptarshi; Roy, Nayan; Singh, T. Sanjoy; Chattopadhyay, Nitin

2018-01-01

The present work reports detailed photophysics of a coumarin based Schiff base, namely, (E)-7-(((8-hydroxyquinolin-2-yl)methylene)amino)-4-methyl-2H-chromen-2-one (HMC) in different solvents of varying polarity exploiting steady state absorption, fluorescence and time resolved fluorescence spectroscopy. The dominant photophysical features of HMC are discussed in terms of emission from an intramolecular charge transfer (ICT) excited state. Molecular orbital (MO) diagrams as obtained from DFT based computational analysis confirms the occurrence of charge transfer from 8‧-hydroxy quinoline moiety of the molecule to the coumarin part. The notable difference in the photophysical response of HMC from its analogous coumarin (C480) lies in a lower magnitude of fluorescence quantum yield of the former, particularly in the solvents of low polarity, which is rationalized by considering the higher rate of non-radiative decay of HMC in apolar solvents. Phosphorescence emission as well as phosphorescence lifetime of HMC has also been reported in 77 K frozen matrix.

Light emission in forward and reverse bias operation in OLED with amorphous silicon carbon nitride thin films

NASA Astrophysics Data System (ADS)

Reyes, R.; Cremona, M.; Achete, C. A.

2011-01-01

Amorphous silicon carbon nitride (a-SiC:N) thin films deposited by magnetron sputtering were used in the structure of an organic light emitting diode (OLED), obtaining an OLED operating in forward and reverse bias mode. The device consist of the heterojunction structure ITO/a-SiC:N/Hole Transport Layer (HTL)/ Electron Transport Layer (ETL)/a-SiC:N/Al. As hole transporting layer was used a thin film of 1-(3-methylphenyl)-1,2,3,4 tetrahydroquinoline - 6 - carboxyaldehyde - 1,1'- diphenylhydrazone (MTCD), while the tris(8-hydroxyquinoline aluminum) (Alq3) is used as electron transport and emitting layer. A significant increase in the voltage operation compared to the conventional ITO/MTCD/Alq3/Al structure was observed, so the onset of electroluminescence occurs at about 22 V in the forward and reverse bias mode of operation. The electroluminescence spectra is similar in both cases, only slightly shifted 0.14 eV to lower energies in relation to the conventional device.

Conformal and highly luminescent monolayers of Alq3 prepared by gas-phase molecular layer deposition.

PubMed

Räupke, André; Albrecht, Fabian; Maibach, Julia; Behrendt, Andreas; Polywka, Andreas; Heiderhoff, Ralf; Helzel, Jonatan; Rabe, Torsten; Johannes, Hans-Hermann; Kowalsky, Wolfgang; Mankel, Eric; Mayer, Thomas; Görrn, Patrick; Riedl, Thomas

2014-01-22

The gas-phase molecular layer deposition (MLD) of conformal and highly luminescent monolayers of tris(8-hydroxyquinolinato)aluminum (Alq3) is reported. The controlled formation of Alq3 monolayers is achieved for the first time by functionalization of the substrate with amino groups, which serve as initial docking sites for trimethyl aluminum (TMA) molecules binding datively to the amine. Thereby, upon exposure to 8-hydroxyquinoline (8-HQ), the self-limiting formation of highly luminescent Alq3 monolayers is afforded. The growth process and monolayer formation were studied and verified by in situ quartz crystal monitoring, optical emission and absorption spectroscopy, and X-ray photoelectron spectroscopy. The nature of the MLD process provides an avenue to coat arbitrarily shaped 3D surfaces and porous structures with high surface areas, as demonstrated in this work for silica aerogels. The concept presented here paves the way to highly sensitive luminescent sensors and dye-sensitized metal oxides for future applications (e.g., in photocatalysis and solar cells).

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

PubMed Central

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

2011-01-01

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

Molecular origin of differences in hole and electron mobility in amorphous Alq3--a multiscale simulation study.

PubMed

Fuchs, Andreas; Steinbrecher, Thomas; Mommer, Mario S; Nagata, Yuki; Elstner, Marcus; Lennartz, Christian

2012-03-28

In order to determine the molecular origin of the difference in electron and hole mobilities of amorphous thin films of Alq(3) (meridional Alq(3) (tris(8-hydroxyquinoline) aluminium)) we performed multiscale simulations covering quantum mechanics, molecular mechanics and lattice models. The study includes realistic disordered morphologies, polarized site energies to describe diagonal disorder, quantum chemically calculated transfer integrals for the off-diagonal disorder, inner sphere reorganization energies and an approximative scheme for outer sphere reorganization energies. Intermolecular transfer rates were calculated via Marcus-theory and mobilities were simulated via kinetic Monte Carlo simulations and by a Master Equation approach. The difference in electron and hole mobility originates from the different localization of charge density in the radical anion (more delocalized) compared to the radical cation (more confined). This results in higher diagonal disorder for holes and less favourable overlap properties for the hole transfer integrals leading to an overall higher electron mobility.

Lithium hydride doped intermediate connector for high-efficiency and long-term stable tandem organic light-emitting diodes.

PubMed

Ding, Lei; Tang, Xun; Xu, Mei-Feng; Shi, Xiao-Bo; Wang, Zhao-Kui; Liao, Liang-Sheng

2014-10-22

Lithium hydride (LiH) is employed as a novel n-dopant in the intermediate connector for tandem organic light-emitting diodes (OLEDs) because of its easy coevaporation with other electron transporting materials. The tandem OLEDs with two and three electroluminescent (EL) units connected by a combination of LiH doped 8-hydroxyquinoline aluminum (Alq3) and 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN) demonstrate approximately 2-fold and 3-fold enhancement in current efficiency, respectively. In addition, no extra voltage drop across the intermediate connector is observed. Particularly, the lifetime (T75%) in the tandem OLED with two and three EL units is substantially improved by 3.8 times and 7.4 times, respectively. The doping effect of LiH into Alq3, the charge injection, and transport characteristics of LiH-doped Alq3 are further investigated by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoemission spectroscopy (XPS).

Desferrioxamine and desferrioxamine-caffeine as carriers of aluminum and gallium to microbes via the Trojan Horse Effect.

PubMed

Huayhuaz, Jesus Antonio Alvarado; Vitorino, Hector Aguilar; Campos, Othon Souto; Serrano, Silvia Helena Pires; Kaneko, Telma Mary; Espósito, Breno Pannia

2017-05-01

Iron acquisition by bacteria and fungi involves in several cases the promiscuous usage of siderophores. Thus, antibiotic resistance from these microorganisms can be circumvented through a strategy of loading toxic metals into siderophores (Trojan Horse Effect). Desferrioxamine (dfo) and its cell-permeant derivative desferrioxamine-caffeine (dfcaf) were complexed with aluminum or gallium for this purpose. The complexes Me(dfo) and Me(dfcaf) (Me=Al 3+ and Ga 3+ ) were synthesized and characterized by mass spectroscopy and cyclic voltammetry. Their relative stabilities were studied through competitive equilibria with fluorescent probes calcein, fluorescein-desferrioxamine and 8-hydroxyquinoline. Me(dfo) and Me(dfcaf) were consistently more toxic than free Me 3+ against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans, demonstrating the Trojan Horse Effect. Wide spectrum antimicrobial action can be obtained by loading non-essential or toxic metal ions to microbes via a convenient siderophore carrier. Copyright © 2017 Elsevier GmbH. All rights reserved.

The Blue-Shift of Photoluminescence Spectra of Zinc Complexes of 8-Hydroxyquinoline by Addition of ZnO Nanoparticles

NASA Astrophysics Data System (ADS)

Keshmiri, Laleh; Elahi, Seyed Mohammad; Jafari, Mohammad Reza; Jafari, Fatemeh; Parhizgar, Sara Sadat

2018-02-01

In this research, an organo-metallic complex based on zinc ions (Znq2), which can be used in organic light-emitting diodes, was investigated. Nanoparticles of ZnO were produced and added to the Znq2 complex. By means of x-ray diffraction, the structure of Znq2 complex and ZnO nanoparticles and the energy levels of them were determined from cyclic-voltammetry analysis. From thermal gravimetric studies, it was found that the complexes have a high thermal stability in the air atmosphere. The purity of samples was confirmed by Fourier transform infrared spectroscopy. The maximum intensity of the photoluminescence spectrum of Znq2 occurred at 565 nm and showed a blue shift to 511 nm by adding ZnO nanoparticles to the Znq2 complex. The optical and electrical properties of the Znq2 and the mixture of Znq2 and ZnO nano powders were studied in order to find any possible applications in organic light emitting devices.

D.C. electrical conductivity and conduction mechanism of some azo sulfonyl quinoline ligands and uranyl complexes.

PubMed

El-Ghamaz, N A; Diab, M A; El-Sonbati, A Z; Salem, O L

2011-12-01

Supramolecular coordination of dioxouranium(VI) heterochelates 5-sulphono-7-(4'-X phenylazo)-8-hydroxyquinoline HL(n) (n=1, X=CH(3); n=2, X=H; n=3, X=Cl; n=4, X=NO(2)) have been prepared and characterized with various physico-chemical techniques. The infrared spectral studies showed a monobasic bidentate behavior with the oxygen and azonitrogen donor system. The temperature dependence of the D.C. electrical conductivity of HL(n) ligands and their uranyl complexes has been studied in the temperature range 305-415 K. The thermal activation energies E(a) for HL(n) compounds were found to be in the range 0.44-0.9 eV depending on the nature of the substituent X. The complexation process decreased E(a) values to the range 0.043-045 eV. The electrical conduction mechanism has been investigated for all samples under investigation. It was found to obey the variable range hopping mechanism (VRH). Copyright © 2011 Elsevier B.V. All rights reserved.

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.

Effect of Zinc Oxide Doping on Electroluminescence and Electrical Behavior of Metalloporphyrins-Doped Samarium Complex

NASA Astrophysics Data System (ADS)

Janghouri, Mohammad; Amini, Mostafa M.

2018-02-01

Samarium complex [(Sm(III)] as a new host material was used for preparation of red organic light-emitting diodes (OLEDs). Devices with configurations of indium-doped tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):(poly(styrenesulfonate) (PEDOT:PSS (50 nm)/polyvinyl carbazole (PVK):[zinc oxide (ZnO)] (50 nm)/[(Sm(III)]:[zinc(II) 2,3-tetrakis(dihydroxyphenyl)-porphyrin and Pt(II) 2,3-dimethoxyporphyrin] (60 nm)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) (15 nm)/Al (150 nm) have been fabricated and investigated. An electroplex occurring at the (PVK/Sm: Pt(II) 2,3-dimethoxyporphyrin) interface has been suggested when ZnO nanoparticles were doped in PVK. OLED studies have revealed that the photophysical characteristics and electrical behavior of devices with ZnO nanoparticles are much better than those of devices with pure PVK. The efficiency of devices based on [(Sm(III)] was superior than that of known aluminum tris(8-hydroxyquinoline) (Alq3) and also our earlier reports on red OLEDs under the same conditions.

Dipole-modified graphene with ultrahigh gas sensibility

NASA Astrophysics Data System (ADS)

Jia, Ruokun; Xie, Peng; Feng, Yancong; Chen, Zhuo; Umar, Ahmad; Wang, Yao

2018-05-01

This study reports the supramolecular assembly of functional graphene-based materials with ultrahigh gas sensing performances which are induced by charge transfer enhancement. Two typical Donor-π-Accepter (D-π-A) structure molecules 4-aminoquinoline (4AQ, μ = 3.17 Debye) and 4-hydroxyquinoline (4HQ, μ = 1.98 Debye), with different charge transfer enhancing effects, were selected to modify reduce oxide graphene (rGO) via supramolecular assembly. Notably, compared to the 4HQ-rGO, the 4AQ-rGO exhibits more significant increase of gas response (Ra/Rg = 3.79) toward 10 ppm NO2, which is ascribed to the larger dipole moment (μ) of 4AQ and hence the more intensive enhancing effect of charge transfer on the interface of rGO. Meanwhile, 4AQ-rGO sensors also reveal superior comprehensive gas sensing performances, including excellent gas sensing selectivity, linearity, repeatability and stability. It is believed that the present work demonstrates an effective supramolecular approach of modifying rGO with strong dipoles to significantly improve gas sensing properties of graphene-based materials.

SPR sensors for monitoring the degradation processes of Eu(dbm)3(phen) and Alq3 thin films under atmospheric and UVA exposure

NASA Astrophysics Data System (ADS)

Del Rosso, T.; Zaman, Q.; Cremona, M.; Pandoli, O.; Barreto, A. R. J.

2018-06-01

The degradation processes of tris(8-hydroxyquinoline) (Alq3) and tris(dibenzoylmethane) mono(1,10-phenanthroline)europium(III) (Eu(dbm)3(phen)) thin films are investigated by the use of AFM, photoluminescence and SPR spectroscopy. The plasmonic sensors are operated both in air and nitrogen environments, where they are irradiated with controlled doses of UVA radiation. AFM results don't reveal the formation of heterogeneous phases and crystallization under air exposure. The organic thin films change their refractive index under both types of exposure and act as a protective layer against oxidation for the SiO2/MPTS/metal interface of the plasmonic sensors. SPR measurements reveal a strict correlation between the refractive index increase and quenching of the photoluminescence of the organic thin films. The results are promising for the development of compact plasmonic UVA dosimeters in the surface plasmon coupled emission configuration (SPCE) with lanthanide β-diketonate complex materials (patent pending).

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

Evidence for alkali metal formation at a cathode interface of organic electroluminescent devices by thermal decomposition of alkali metal carboxylates during their vapor deposition

NASA Astrophysics Data System (ADS)

Ganzorig, Chimed; Fujihira, Masamichi

2004-11-01

This study examines the possibility of thermal decomposition of Na salts of acetate, benzoate, and fluoride during vacuum vapor deposition using a quartz crystal microbalance to measure negative frequency shift (Δf) caused by increasing mass deposited from the same amount of source materials. Cs acetate is also examined. We compare the negative frequency shift-source current (Δf -I) curves of the Na salts with those of organic materials such as tris(8-hydroxyquinoline)aluminum and N ,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine. CH3COONa and C6H5COONa exhibit much lower Δf than the organic materials. CH3COOCs gives much larger Δf than CH3COONa due to the higher atomic weight of Cs. These exhibit clear evidence for alkali metal formation by thermal decomposition during vapor deposition of alkali metal carboxylates.

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

DOE PAGES

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

2016-02-22

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]styrylbenzene (DSA-Ph) in mixtures with aluminum-tris(8-hydroxyquinoline) (Alq 3) by spectroscopic ellipsometry and IR dichroism. We find that molecular orientation is controlled by the ratio of the substrate temperature during deposition and the glassmore » transition temperature of the mixture. Furthermore, 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.« less

Optimation and Determination of Fe-Oxinate Complex by Using High Performance Liquid Chromatography

NASA Astrophysics Data System (ADS)

Oktavia, B.; Nasra, E.; Sary, R. C.

2018-04-01

The need for iron will improve the industrial processes that require iron as its raw material. Control of industrial iron waste is very important to do. One method of iron analysis is to conduct indirect analysis of iron (III) ions by complexing with 8-Hydroxyquinoline or oxine. In this research, qualitative and quantitative tests of iron (III) ions in the form of complex with oxine. The analysis was performed using HPLC at a wavelength of 470 nm with an ODS C18 column. Three methods of analysis were performed: 1) Fe-oxinate complexes were prepared in an ethanol solvent so no need for separation anymore, (2) Fe-oxinate complexes were made in chloroform so that a solvent extraction was required before the complex was injected into the column while the third complex was formed in the column, wherein the eluent contains the oxide and the metal ions are then injected. The resulting chromatogram shows that the 3rd way provides a better chromatogram for iron analysis.

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carvalho, R. S.; Ávila, H. C.; Cremona, M., E-mail: cremona@fis.puc-rio.br

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 OMARmore » 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.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wenjin, Zeng; Ran, Bi; Hongmei, Zhang, E-mail: iamhmzhang@njupt.edu.cn, 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 hostmore » 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.« less

Improved electron injection in spin coated Alq3 incorporated ZnO thin film in the device for solution processed OLEDs

NASA Astrophysics Data System (ADS)

Dasi, Gnyaneshwar; Ramarajan, R.; Thangaraju, Kuppusamy

2018-04-01

We deposit tris-(8-hydroxyquinoline)aluminum (Alq3) incorporated zinc oxide (ZnO) thin films by spin coating method under the normal ambient. It showed the higher transmittance (90% at 550 nm) when compared to that (80% at 550 nm) of spin coated pure ZnO film. SEM studies show that the Alq3 incorporation in ZnO film also enhances the formation of small sized particles arranged in the network of wrinkles on the surface. XRD reveals the improved crystalline properties upon Alq3 inclusion. We fabricate the electron-only devices (EODs) with the structure of ITO/spin coated ZnO:Alq3 as ETL/Alq3 interlayer/LiF/Al. The device showed the higher electron current density of 2.75 mA/cm2 at 12V when compared to that (0.82 mA/cm2 at 12V) of the device using pure ZnO ETL. The device results show that it will be useful to fabricate the low-cost solution processed OLEDs for future lighting and display applications.

Stabilities and Biological Activities of Vanadium Drugs: What is the Nature of the Active Species?

PubMed

Levina, Aviva; Lay, Peter A

2017-07-18

Diverse biological activities of vanadium(V) drugs mainly arise from their abilities to inhibit phosphatase enzymes and to alter cell signaling. Initial interest focused on anti-diabetic activities but has shifted to anti-cancer and anti-parasitic drugs. V-based anti-diabetics are pro-drugs that release active components (e.g., H 2 VO 4 - ) in biological media. By contrast, V anti-cancer drugs are generally assumed to enter cells intact; however, speciation studies indicate that nearly all drugs are likely to react in cell culture media during in vitro assays and the same would apply in vivo. The biological activities are due to V V and/or V IV reaction products with cell culture media, or the release of ligands (e.g., aromatic diimines, 8-hydroxyquinolines or thiosemicarbazones) that bind to essential metal ions in the media. Careful consideration of the stability and speciation of V complexes in cell culture media and in biological fluids is essential to design targeted V-based anti-cancer therapies. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optically active charge transfer in hybrids of Alq3 nanoparticles and MoS2 monolayer

NASA Astrophysics Data System (ADS)

Ghimire, Ganesh; Dhakal, Krishna P.; Neupane, Guru P.; Jo, Seong Gi; Kim, Hyun; Seo, Changwon; Lee, Young Hee; Joo, Jinsoo; Kim, Jeongyong

2017-05-01

Organic/inorganic hybrid structures have been widely studied because of their enhanced physical and chemical properties. Monolayers of transition metal dichalcogenides (1L-TMDs) and organic nanoparticles can provide a hybridization configuration between zero- and two-dimensional systems with the advantages of convenient preparation and strong interface interaction. Here, we present such a hybrid system made by dispersing π-conjugated organic (tris (8-hydroxyquinoline) aluminum(III)) (Alq3) nanoparticles (NPs) on 1L-MoS2. Hybrids of Alq3 NP/1L-MoS2 exhibited a two-fold increase in the photoluminescence of Alq3 NPs on 1L-MoS2 and the n-doping effect of 1L-MoS2, and these spectral and electronic modifications were attributed to the charge transfer between Alq3 NPs and 1L-MoS2. Our results suggested that a hybrid of organic NPs/1L-TMD can offer a convenient platform to study the interface interactions between organic and inorganic nano objects and to engineer optoelectronic devices with enhanced performance.

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

NASA Astrophysics Data System (ADS)

Minagawa, Masahiro; Takahashi, Noriko

2016-02-01

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

Control of resonant wavelength from organic light-emitting materials by use of a Fabry-Perot microcavity structure.

PubMed

Jung, Boo Young; Kim, Nam Young; Lee, Changhee; Hwangbo, Chang Kwon; Seoul, Chang

2002-06-01

We report the fabrication of Fabry-Perot microcavity structures with the organic light-emitting material tris-(8-hydroxyquinoline) aluminum (Alq3) and derive their optical properties by measuring their photoluminescence (PL) and absorption. Silver and a TiO2-SiO2 multilayer were used as metal and dielectric reflectors, respectively, in a Fabry-Perot microcavity structure. Three types of microcavity were prepared: type A consisted of [air[Ag[Alq3]Ag]glass]; type B, of [air[dielectric[Alq3]dielectric]glass]; and type C, of [air[Ag[Alq2]dielectric]glass]. A bare Alq3 film of [air[Alq3]glass] had its PL peak near 514 nm, and its full width at half-maximum (FWHM) was 80 nm. The broad FWHM of a bare Alq3 film was reduced to 15-27.5, 7-10.5, and 16-16.6 nm for microcavity types A, B, and C, respectively. Also, we could control the PL peak of the microcavity structure by changing the spacer thickness, the amount of phase change on reflection, and the angle of incidence.

Optically active charge transfer in hybrids of Alq3 nanoparticles and MoS2 monolayer.

PubMed

Ghimire, Ganesh; Dhakal, Krishna P; Neupane, Guru P; Gi Jo, Seong; Kim, Hyun; Seo, Changwon; Hee Lee, Young; Joo, Jinsoo; Kim, Jeongyong

2017-05-05

Organic/inorganic hybrid structures have been widely studied because of their enhanced physical and chemical properties. Monolayers of transition metal dichalcogenides (1L-TMDs) and organic nanoparticles can provide a hybridization configuration between zero- and two-dimensional systems with the advantages of convenient preparation and strong interface interaction. Here, we present such a hybrid system made by dispersing π-conjugated organic (tris (8-hydroxyquinoline) aluminum(III)) (Alq 3 ) nanoparticles (NPs) on 1L-MoS 2 . Hybrids of Alq 3 NP/1L-MoS 2 exhibited a two-fold increase in the photoluminescence of Alq 3 NPs on 1L-MoS 2 and the n-doping effect of 1L-MoS 2 , and these spectral and electronic modifications were attributed to the charge transfer between Alq 3 NPs and 1L-MoS 2 . Our results suggested that a hybrid of organic NPs/1L-TMD can offer a convenient platform to study the interface interactions between organic and inorganic nano objects and to engineer optoelectronic devices with enhanced performance.

New cyclometalated Iridium(III) beta-dicetone complex as phosphorescent dopant in Organic light emitting devices

NASA Astrophysics Data System (ADS)

Ivanov, P.; Petrova, P.; Stanimirov, S.; Tomova, R.

2017-01-01

A new Bis[4-(benzothiazolato-N,C2‧-2-yl)-N,N-dimethylaniline]Iridium(III) acetylacetonate (Me2N-bt) 2Ir(acac) was synthesized and identified by 1H NMR and elemental analysis. The application of the new compound as a dopant in the hole transporting layer (HTL) of Organic light emitting diode (OLED) structure: HTL/EL/ETL, where HTL was N,N’-bis(3-methylphenyl)-N,N’-diphenylbenzidine (TPD), incorporated in Poly(N-vinylcarbazole) (PVK) matrix, EL - electroluminescent layer of Bis(8-hydroxy-2-methylquinoline)-(4-phenylpheno-xy)aluminum (BAlq) and ETL - electron-transporting layer of Tris-(8-hydroxyquinoline) aluminum (Alq3) or Bis[2-(2-benzothiazoly) phenolato]zinc (Zn(btz)2). We established that the electroluminescent spectra of OLEDs at different concentrations of the dopant were basically the sum of the greenish-blue emission of BAlq and yellowish-green emission of Ir complex. It was found that with increasing of the dopant concentration the relative electroluminescent intensity of Iridium complex emission increased and this of BAlq decreased and as a result the fine tuning of OLED color was observed.

Induction of expression and co-localization of heat shock polypeptides with the polyalanine expansion mutant of poly(A)-binding protein N1 after chemical stress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Qishan; Bag, Jnanankur

Formation of nuclear inclusions consisting of aggregates of a polyalanine expansion mutant of nuclear poly(A)-binding protein (PABPN1) is the hallmark of oculopharyngeal muscular dystrophy (OPMD). OPMD is a late onset autosomal dominant disease. Patients with this disorder exhibit progressive swallowing difficulty and drooping of their eye lids, which starts around the age of 50. Previously we have shown that treatment of cells expressing the mutant PABPN1 with a number of chemicals such as ibuprofen, indomethacin, ZnSO{sub 4}, and 8-hydroxy-quinoline induces HSP70 expression and reduces PABPN1 aggregation. In these studies we have shown that expression of additional HSPs including HSP27, HSP40,more » and HSP105 were induced in mutant PABPN1 expressing cells following exposure to the chemicals mentioned above. Furthermore, all three additional HSPs were translocated to the nucleus and probably helped to properly fold the mutant PABPN1 by co-localizing with this protein.« less

Preferential deprotonation and conformational stability of dicarboxylic acids: A packing effect

NASA Astrophysics Data System (ADS)

Barooah, Nilotpal; Singh, W. Marjit; Baruah, Jubaraj B.

2008-03-01

Crystal structures of a series of salts of (6-carboxymethyl-1,3,5,7-tetraoxo-3,5,6,7-tetrahydro-1 H-pyrrolo[3,4- f]isoindol-2-yl)-acetic acid ( 1) and 2-carboxymethyl-1,3-dioxo-2,3-dihydro-1 H-isoinodole-5-carboxylic acid ( 2) with different polynuclear nitrogen containing heterocyclic compounds, namely, quinoline, 1,10-phenanthroline and 8-hydroxyquinoline are determined. In the case of salt of 1 with quinolinium and 1,10-phenanthrolinium cations syn disposition between the carboxylate anion and carboxylic acid groups is observed; whereas in the case of the 8-hydroxyquinolinium salt of 1, it is the anti disposition. It is also found that the solid state structure of 1,10-phenanthrolinium salt of 2 has deprotonation at the aromatic end, whereas in 8-hydroxy-quinolinium salt of 2 is formed by deprotonation of carboxylic acid group on the aliphatic side. The dicarboxylic acid 2 forms 1:2 co-crystals with quinoline. From crystallographic study it is shown that the weak interactions become prominent in stabilising the observed conformers and also in stabilising specific deprotonated species.

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.

Newly Designed Quinolinol Inhibitors Mitigate the Effects of Botulinum Neurotoxin A in Enzymatic, Cell-Based, and ex Vivo Assays.

PubMed

Bremer, Paul T; Adler, Michael; Phung, Cecilia H; Singh, Ajay K; Janda, Kim D

2017-01-12

Botulinum neurotoxin A (BoNT/A) is one of the most deadly toxins and is the etiological agent of the potentially fatal condition, botulism. Herein, we investigated 8-hydroxyquinoline (quinolin-8-ol) as a potential inhibitor scaffold for preventing the deadly neurochemical effects of the toxin. Quinolinols are known chelators that can disrupt the BoNT/A metalloprotease zinc-containing active site, thus impeding its proteolysis of the endogenous protein substrate, synaptosomal-associated protein 25 (SNAP-25). By use of this information, the structure-activity relationship (SAR) of the quinolinol-5-sulfonamide scaffold was explored through preparation of a crude sulfonamide library and evaluation of the library in a BoNT/A LC enzymatic assay. Potency optimization of the sulfonamide hit compounds was undertaken as informed by docking studies, granting a lead compound with a submicromolar K i . These quinolinol analogues demonstrated inhibitory activity in a cell-based model for SNAP-25 cleavage and an ex vivo assay for BoNT/A-mediated muscle paralysis.

Study of electron mobility in small molecular SAlq by transient electroluminescence method

NASA Astrophysics Data System (ADS)

Kumar, Pankaj; Jain, S. C.; Kumar, Vikram; Chand, Suresh; Kamalasanan, M. N.; Tandon, R. P.

2007-12-01

The study of electron mobility of bis(2-methyl 8-hydroxyquinoline) (triphenyl siloxy) aluminium (SAlq) by transient electroluminescence (EL) is presented. An EL device is fabricated in bilayer, ITO/N,N'-diphenyl-N, N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD)/SAlq/LiF/Al configuration. The temporal evaluation of the EL with respect to the step voltage pulse is characterized by a delay time followed by a fast initial rise, which is followed by a slower rise. The delay time between the applied electrical pulse and the onset of EL is correlated with the carrier mobility (electron in our case). Transient EL studies for SAlq have been carried out at different temperatures and different applied electric fields. The electron mobility in SAlq is found to be field and temperature dependent and calculated to be 6.9 × 10-7 cm2 V-1 s-1 at 2.5 × 106 V cm-1 and 308 K. The EL decays immediately as the voltage is turned off and does not depend on the amplitude of the applied voltage pulse or dc offset.

Photo-physics study of an hydroxy-quinoline derivative as inhibitor of Pim-1 kinase: ultraviolet-visible linear dichroism spectroscopy and quantum chemical calculations.

PubMed

Lamhasni, T; Ait Lyazidi, S; Hnach, M; Haddad, M; Desmaële, D; Spanget-Larsen, J; Nguyen, D D; Ducasse, L

2013-09-01

The photophysical properties of the antiviral 7-nicotinoyl-styrylquinoline (MB96) were investigated by means of UV-Vis linear dichroism (LD) spectroscopy on molecular samples aligned in stretched polyvinylalcohol (PVA), supported by time dependent density functional theory (TD-DFT) calculations. Experimentally, the directions of the transitions moments with respect to the long axis of the molecule were deduced from the orientation K factors, determined by means of "trial-and-error" procedure. The absorption spectrum presents two parts. The main transition in the lowest energy part, observed around 365 nm and showing the highest K value 0.8, is longitudinally in-plane polarized. The highest energy part which is extended between 230 and 320 nm, large, diffuse, and of weak intensity, shows estimated K values between 0.2 and 0.5. This complex structure is transversally polarized with some contamination by the longitudinal character of the first strong band. The TD-DFT results agree fairly well with the LD measurements. Copyright © 2013 Elsevier B.V. All rights reserved.

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 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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02267g

Composition, Characterization and Antibacterial activity of Mn(II), Co(II),Ni(II), Cu(II) Zn(II) and Cd(II) mixed ligand complexes Schiff base derived from Trimethoprim with 8-Hydroxy quinoline

NASA Astrophysics Data System (ADS)

Numan, Ahmed T.; Atiyah, Eman M.; Al-Shemary, Rehab K.; Ulrazzaq, Sahira S. Abd

2018-05-01

New Schiff base ligand 2-((4-amino-5-(3, 4, 5-trimethoxybenzyl) pyrimidin-2-ylimino) (phenyl)methyl)benzoic acid] = [HL] was synthesized using microwave irradiation trimethoprim and 2-benzoyl benzoic acid. Mixed ligand complexes of Mn((II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) are reacted in ethanol with Schiff base ligand [HL] and 8-hydroxyquinoline [HQ] then reacted with metal salts in ethanol as a solvent in (1:1:1) ratio. The ligand [HL] is characterized by FTIR, UV-Vis, melting point, elemental microanalysis (C.H.N), 1H-NMR, 13C-NMR, and mass spectra. The mixed ligand complexes are characterized by infrared spectra, electronic spectra, (C.H.N), melting point, atomic absorption, molar conductance and magnetic moment measurements. These measurements indicate that the ligand [HL] coordinates with metal (II) ion in a tridentate manner through the oxygen and nitrogen atoms of the ligand, octahedral structures are suggested for these complexes. Antibacterial activity of the ligands [HL], [HQ] and their complexes are studied against (gram positive) and (gram negative) bacteria.

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

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

PubMed

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

2016-02-05

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

Quantitative Determining of Ultra-Trace Aluminum Ion in Environmental Samples by Liquid Phase Microextraction Assisted Anodic Stripping Voltammetry.

PubMed

Zhang, Liuyang; Luo, Jinju; Shen, Xinyu; Li, Chunya; Wang, Xian; Nie, Bei; Fang, Huaifang

2018-05-10

Direct detecting of trace amount Al(III) in aqueous solution by stripping voltammetry is often frustrated by its irreversible reduction, resided at −1.75 V (vs. Ag/AgCl reference), which is in a proximal potential of proton reduction. Here, we described an electroanalytical approach, combined with liquid phase microextraction (LPME) using ionic liquid (IL), to quantitatively assess trace amount aluminum in environmental samples. The Al(III) was caged by 8-hydroxyquinoline, forming a superb hydrophobic metal⁻chelate, which sequentially transfers and concentrates in the bottom layer of IL-phase during LPME. The preconcentrated Al(III) was further analyzed by a square-wave anodic stripping voltammetry (SW-ASV). The resulting Al-deposited electrodes were characterized by scanning electron microscopy and powder X-ray diffraction, showing the intriguing amorphous nanostructures. The method developed provides a linear calibration ranging from 0.1 to 1.2 ng L −1 with a correlation coefficient of 0.9978. The LOD attains as low as 1 pmol L −1 , which reaches the lowest report for Al(III) detection using electroanalytical techniques. The applicable methodology was implemented for monitoring Al(III) in commercial distilled water.

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. Copyright © 2011 Elsevier B.V. All rights reserved.

Atomistic simulation on charge mobility of amorphous tris(8-hydroxyquinoline) aluminum (Alq3): origin of Poole-Frenkel-type behavior.

PubMed

Nagata, Yuki; Lennartz, Christian

2008-07-21

The atomistic simulation of charge transfer process for an amorphous Alq(3) system is reported. By employing electrostatic potential charges, we calculate site energies and find that the standard deviation of site energy distribution is about twice as large as predicted in previous research. The charge mobility is calculated via the Miller-Abrahams formalism and the master equation approach. We find that the wide site energy distribution governs Poole-Frenkel-type behavior of charge mobility against electric field, while the spatially correlated site energy is not a dominant mechanism of Poole-Frenkel behavior in the range from 2x10(5) to 1.4x10(6) V/cm. Also we reveal that randomly meshed connectivities are, in principle, required to account for the Poole-Frenkel mechanism. Charge carriers find a zigzag pathway at low electric field, while they find a straight pathway along electric field when a high electric field is applied. In the space-charge-limited current scheme, the charge-carrier density increases with electric field strength so that the nonlinear behavior of charge mobility is enhanced through the strong charge-carrier density dependence of charge mobility.

Chemical failure modes of AlQ3-based OLEDs: AlQ3 hydrolysis.

PubMed

Knox, John E; Halls, Mathew D; Hratchian, Hrant P; Schlegel, H Bernhard

2006-03-28

Tris(8-hydroxyquinoline)aluminum(III), AlQ3, is used in organic light-emitting diodes (OLEDs) as an electron-transport material and emitting layer. The reaction of AlQ3 with trace H2O has been implicated as a major failure pathway for AlQ3-based OLEDs. Hybrid density functional calculations have been carried out to characterize the hydrolysis of AlQ3. The thermochemical and atomistic details for this important reaction are reported for both the neutral and oxidized AlQ3/AlQ3+ systems. In support of experimental conclusions, the neutral hydrolysis reaction pathway is found to be a thermally activated process, having a classical barrier height of 24.2 kcal mol(-1). First-principles infrared and electronic absorption spectra are compared to further characterize AlQ3 and the hydrolysis pathway product, AlQ2OH. The activation energy for the cationic AlQ3 hydrolysis pathway is found to be 8.5 kcal mol(-1) lower than for the neutral reaction, which is significant since it suggests a role for charge imbalance in promoting chemical failure modes in OLED devices.

Coumarin derivatives bearing benzoheterocycle moiety: synthesis, cholinesterase inhibitory, and docking simulation study

PubMed Central

Hirbod, Kimia; Jalili-baleh, Leili; Nadri, Hamid; ebrahimi, Seyed esmaeil Sadat; Moradi, Alireza; Pakseresht, Bahar; Foroumadi, Alireza; Shafiee, Abbas; Khoobi, Mehdi

2017-01-01

Objective(s): To investigate the efficiency of a novel series of coumarin derivatives bearing benzoheterocycle moiety as novel cholinesterase inhibitors. Materials and Methods: Different 7-hydroxycoumarin derivatives were synthesized via Pechmann or Knoevenagel condensation and conjugated to different benzoheterocycle (8-hydroxyquinoline, 2-mercaptobenzoxazole or 2-mercaptobenzimidazole) using dibromoalkanes 3a-m: Final compounds were evaluated against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) by Ellman’s method. Kinetic study of AChE inhibition and ligand-protein docking simulation were also carried out for the most potent compound 3b. Results: Some of the compounds revealed potent and selective activity against AChE. Compound 3b containing the quinoline group showed the best activity with an IC50 value of 8.80 μM against AChE. Kinetic study of AChE inhibition revealed the mixed-type inhibition of the enzyme by compound 3b. Ligand-protein docking simulation also showed that the flexibility of the hydrophobic five carbons linker allows the quinoline ring to form π-π interaction with Trp279 in the PAS. Conclusion: We suggest these synthesized compounds could become potential leads for AChE inhibition and prevention of AD symptoms. PMID:28868119

Investigation of iron(III) reduction and trace metal interferences in the determination of dissolved iron in seawater using flow injection with luminol chemiluminescence detection.

PubMed

Ussher, Simon J; Milne, Angela; Landing, William M; Attiq-ur-Rehman, Kakar; Séguret, Marie J M; Holland, Toby; Achterberg, Eric P; Nabi, Abdul; Worsfold, Paul J

2009-10-12

A detailed investigation into the performance of two flow injection-chemiluminescence (FI-CL) manifolds (with and without a preconcentration column) for the determination of sub-nanomolar dissolved iron (Fe(II)+Fe(III)), following the reduction of Fe(III) by sulphite, in seawater is described. Kinetic experiments were conducted to examine the efficiency of reduction of inorganic Fe(III) with sulphite under different conditions and a rigorous study of the potential interference caused by other transition metals present in seawater was conducted. Using 100microM concentrations of sulphite a reduction time of 4h was sufficient to quantitatively reduce Fe(III) in seawater. Under optimal conditions, cobalt(II) and vanadium(IV)/(III) were the major positive interferences and strategies for their removal are reported. Specifically, cobalt(II) was masked by the addition of dimethylglyoxime to the luminol solution and vanadium(IV) was removed by passing the sample through an 8-hydroxyquinoline column in a low pH carrier stream. Manganese(II) also interfered by suppression of the CL response but this was not significant at typical open ocean concentrations.

Determination of As, Cd, Hg and Pb in herbs using slurry sampling electrothermal vaporisation inductively coupled plasma mass spectrometry.

PubMed

Lin, Mei-Ling; Jiang, Shiuh-Jen

2013-12-01

Inductively coupled plasma mass spectrometry coupled with ultrasonic slurry sampling electrothermal vaporisation (USS-ETV-ICP-MS) has been applied to determine As, Cd, Hg and Pb in 0.5% m/v slurries of several herb samples. 1% m/v 8-Hydroxyquinoline was used as the modifier to enhance the ion signals. The influences of instrument operating conditions, slurry preparation and interferences on the ion signals were reported. This method has been applied to the determination of As, Cd, Hg and Pb in NIST SRM 1547 peach leaves and SRM 1573a tomato leaves reference materials and three herb samples purchased from the local market and ground to 150 μm. The analysis results of the standard reference materials agreed with the certified values which are at sub μg g(-1) levels. Precision between sample replicates was better than 4% for all the determinations. The method detection limits estimated from standard addition curves were about 0.3, 0.1, 0.1 and 0.2 ng g(-1) for As, Cd, Hg and Pb, respectively, in original herb samples. Copyright © 2013 Elsevier Ltd. All rights reserved.

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. Copyright © 2014 Elsevier GmbH. All rights reserved.

Therapeutic targeting of oxygen-sensing prolyl hydroxylases abrogates ATF4-dependent neuronal death and improves outcomes after brain hemorrhage in several rodent models

PubMed Central

Karuppagounder, Saravanan S.; Alim, Ishraq; Khim, Soah J.; Bourassa, Megan W.; Sleiman, Sama F.; John, Roseleen; Thinnes, Cyrille C.; Yeh, Tzu-Lan; Demetriades, Marina; Neitemeier, Sandra; Cruz, Dana; Gazaryan, Irina; Killilea, David W.; Morgenstern, Lewis; Xi, Guohua; Keep, Richard F.; Schallert, Timothy; Tappero, Ryan V.; Zhong, Jian; Cho, Sunghee; Maxfield, Frederick R.; Holman, Theodore R.; Culmsee, Carsten; Fong, Guo-Hua; Su, Yijing; Ming, Guo-li; Song, Hongjun; Cave, John W.; Schofield, Christopher J.; Colbourne, Frederick; Coppola, Giovanni; Ratan, Rajiv R.

2017-01-01

Disability or death due to intracerebral hemorrhage (ICH) is attributed to blood lysis, liberation of iron, and consequent oxidative stress. Iron chelators bind to free iron and prevent neuronal death induced by oxidative stress and disability due to ICH, but the mechanisms for this effect remain unclear. We show that the hypoxia-inducible factor prolyl hydroxylase domain (HIF-PHD) family of iron-dependent, oxygen-sensing enzymes are effectors of iron chelation. Molecular reduction of the three HIF-PHD enzyme isoforms in the mouse striatum improved functional recovery after ICH. A low-molecular-weight hydroxyquinoline inhibitor of the HIF-PHD enzymes, adaptaquin, reduced neuronal death and behavioral deficits after ICH in several rodent models without affecting total iron or zinc distribution in the brain. Unexpectedly, protection from oxidative death in vitro or from ICH in vivo by adaptaquin was associated with suppression of activity of the prodeath factor ATF4 rather than activation of an HIF-dependent prosurvival pathway. Together, these findings demonstrate that brain-specific inactivation of the HIF-PHD metalloenzymes with the blood-brain barrier-permeable inhibitor adaptaquin can improve functional outcomes after ICH in several rodent models. PMID:26936506

Molecular Signature of Pseudomonas aeruginosa with Simultaneous Nanomolar Detection of Quorum Sensing Signaling Molecules at a Boron-Doped Diamond Electrode

NASA Astrophysics Data System (ADS)

Buzid, Alyah; Shang, Fengjun; Reen, F. Jerry; Muimhneacháin, Eoin Ó.; Clarke, Sarah L.; Zhou, Lin; Luong, John H. T.; O'Gara, Fergal; McGlacken, Gerard P.; Glennon, Jeremy D.

2016-07-01

Electroanalysis was performed using a boron-doped diamond (BDD) electrode for the simultaneous detection of 2-heptyl-3-hydroxy-4-quinolone (PQS), 2-heptyl-4-hydroxyquinoline (HHQ) and pyocyanin (PYO). PQS and its precursor HHQ are two important signal molecules produced by Pseudomonas aeruginosa, while PYO is a redox active toxin involved in virulence and pathogenesis. This Gram-negative and opportunistic human pathogen is associated with a hospital-acquired infection particularly in patients with compromised immunity and is the primary cause of morbidity and mortality in cystic fibrosis (CF) patients. Early detection is crucial in the clinical management of this pathogen, with established infections entering a biofilm lifestyle that is refractory to conventional antibiotic therapies. Herein, a detection procedure was optimized and proven for the simultaneous detection of PYO, HHQ and PQS in standard mixtures, biological samples, and P. aeruginosa spiked CF sputum samples with remarkable sensitivity, down to nanomolar levels. Differential pulse voltammetry (DPV) scans were also applicable for monitoring the production of PYO, HHQ and PQS in P. aeruginosa PA14 over 8 h of cultivation. The simultaneous detection of these three compounds represents a molecular signature specific to this pathogen.

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 (MTDL) based on the “one molecule, multiple targets” paradigm. Thus, in this context, different series of novel multifunctional molecules with antioxidant, anti-amyloid, anti-inflammatory, and metal-chelating properties able to interact with multiple enzymes of therapeutic interest in AD pathology including acetylcholinesterase, butyrylcholinesterase, and monoamine oxidases A and B have been designed and assessed biologically. This review describes the multiple targets, the design rationale and an in-house MTDL library, bearing the N-benzylpiperidine motif present in donepezil, linked to different heterocyclic ring systems (indole, pyridine, or 8-hydroxyquinoline) with special emphasis on compound ASS234, an N-propargylindole derivative. The description of the in vitro biological properties of the compounds and discussion of the corresponding structure-activity-relationships allows us to highlight new issues for the identification of more efficient MTDL for use in AD therapy. PMID:27252617

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Guohong; Liu, Yong; Li, Baojun

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 takesmore » 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.« less

Effect of thermal annealing on the structural and optical properties of tris-(8-hydroxyquinoline)aluminum(III) (Alq3 ) films.

PubMed

Cuba, M; Muralidharan, G

2015-05-01

Tris-(8-hydroxyquionoline)aluminum (Alq3 ) was synthesized and coated on to a glass substrate using the dip coating method. The structural and optical properties of the Alq3 film after thermal annealing from 50°C to 300°C in 50° steps was studied. The films have been prepared with 2 to 16 layers (42-324 nm). The thickness and thermal annealing of Alq3 films were optimized for maximum luminescence yield. The Fourier transform infrared spectrum confirms the formation of quinoline with absorption in the region 700 - 500/cm. Partial sublimation and decomposition of quinoline ion was observed with the Alq3 films annealed at 300°C. The X-ray diffraction pattern of the Alq3 film annealed at 50°C to 150°C reveals the amorphous nature of the films. The Alq3 film annealed above 150°C were crystalline nature. Film annealed at 150°C exhibits a photoluminescence intensity maximum at 512 nm when excited at 390 nm. The Alq3 thin film deposited with 10 layers (220 nm) at 150°C exhibited maximum luminescence yield. Copyright © 2014 John Wiley & Sons, Ltd.

Measurement of Magnetic Exchange in Asymmetric Lanthanide Dimetallics: Toward a Transferable Theoretical Framework.

PubMed

Giansiracusa, Marcus J; Moreno-Pineda, Eufemio; Hussain, Riaz; Marx, Raphael; Martínez Prada, María; Neugebauer, Petr; Al-Badran, Susan; Collison, David; Tuna, Floriana; van Slageren, Joris; Carretta, Stefano; Guidi, Tatiana; McInnes, Eric J L; Winpenny, Richard E P; Chilton, Nicholas F

2018-02-21

Magnetic exchange interactions within the asymmetric dimetallic compounds [hqH 2 ][Ln 2 (hq) 4 (NO 3 ) 3 ]·MeOH, (Ln = Er(III) and Yb(III), hqH = 8-hydroxyquinoline) have been directly probed with EPR spectroscopy and accurately modeled by spin Hamiltonian techniques. Exploitation of site selectivity via doping experiments in Y(III) and Lu(III) matrices yields simple EPR spectra corresponding to isolated Kramers doublets, allowing determination of the local magnetic properties of the individual sites within the dimetallic compounds. CASSCF-SO calculations and INS and far-IR measurements are all employed to further support the identification and modeling of the local electronic structure for each site. EPR spectra of the pure dimetallic compounds are highly featured and correspond to transitions within the lowest-lying exchange-coupled manifold, permitting determination of the highly anisotropic magnetic exchange between the lanthanide ions. We find a unique orientation for the exchange interaction, corresponding to a common elongated oxygen bridge for both isostructural analogs. This suggests a microscopic physical connection to the magnetic superexchange. These results are of fundamental importance for building and validating model microscopic Hamiltonians to understand the origins of magnetic interactions between lanthanides and how they may be controlled with chemistry.

Therapeutic targeting of oxygen-sensing prolyl hydroxylases abrogates ATF4-dependent neuronal death and improves outcomes after brain hemorrhage in several rodent models

DOE PAGES

Karuppagounder, Saravanan S.; Alim, Ishraq; Khim, Soah J.; ...

2016-03-02

Disability or death due to intracerebral hemorrhage (ICH) is attributed to blood lysis, liberation of iron and consequent oxidative stress. Iron chelators bind to free iron and prevent neuronal death induced by oxidative stress and disability due to ICH, but the mechanisms for this effect remain unclear. Here we show that the hypoxia-inducible factor prolyl-hydroxylase (HIF- PHD) family of iron-dependent oxygen sensing enzymes are effectors of iron chelation. Molecular reduction of the three HIF-PHD enzyme isoforms in mouse striatum improved functional recovery following ICH. A low molecular weight hydroxyquinoline inhibitor of the HIF-PHDs, adaptaquin, reduced neuronal death and behavioral deficitsmore » following ICH in several rodent models without affecting total iron or zinc distribution in the brain. Unexpectedly, protection from oxidative death in vitro or from ICH in vivo by adaptaquin was associated with suppression of expression of the prodeath factor ATF4 rather than activation of a HIF-dependent prosurvival pathway. In conclusion, together these findings demonstrate that brain-specific inactivation of the HIF-PHD metalloenzymes with the blood-brain barrier permeable inhibitor adaptaquin can improve functional outcomes following ICH in multiple rodent species.« less

Precipitation of thin-film organic single crystals by a novel crystal growth method using electrospray and ionic liquid film

NASA Astrophysics Data System (ADS)

Ueda, Hiroyuki; Takeuchi, Keita; Kikuchi, Akihiko

2018-04-01

We report an organic single crystal growth technique, which uses a nonvolatile liquid thin film as a crystal growth field and supplies fine droplets containing solute from the surface of the liquid thin film uniformly and continuously by electrospray deposition. Here, we investigated the relationships between the solute concentration of the supplied solution and the morphology and size of precipitated crystals for four types of fluorescent organic low molecule material [tris(8-hydroxyquinoline)aluminum (Alq3), 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), N,N‧-bis(3-methylphenyl)-N,N‧-diphenylbenzidine (TPD), and N,N-bis(naphthalene-1-yl)-N,N-diphenyl-benzidine (NPB)] using an ionic liquid as the nonvolatile liquid. As the concentration of the supplied solution decreased, the morphology of precipitated crystals changed from dendritic or leaf shape to platelike one. At the solution concentration of 0.1 mg/ml, relatively large platelike single crystals with a diagonal length of over 100 µm were obtained for all types of material. In the experiment using ionic liquid and dioctyl sebacate as nonvolatile liquids, it was confirmed that there is a clear positive correlation between the maximum volume of the precipitated single crystal and the solubility of solute under the same solution supply conditions.

IZO deposited by PLD on flexible substrate for organic heterostructures

NASA Astrophysics Data System (ADS)

Socol, M.; Preda, N.; Stanculescu, A.; Breazu, C.; Florica, C.; Rasoga, O.; Stanculescu, F.; Socol, G.

2017-05-01

In:ZnO (IZO) thin films were deposited on flexible plastic substrates by pulsed laser deposition (PLD) method. The obtained layers present adequate optical and electrical properties competitive with those based on indium tin oxide (ITO). The figure of merit (9 × 10-3 Ω-1) calculated for IZO layers demonstrates that high quality coatings can be prepared by this deposition technique. A thermal annealing (150 °C for 1 h) or an oxygen plasma etching (6 mbar for 10 min.) were applied to the IZO layers to evaluate the influence of these treatments on the properties of the transparent coatings. Using vacuum evaporation, organic heterostructures based on cooper phthalocyanine (CuPc) and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) were deposited on the untreated and treated IZO layers. The optical and electrical properties of the heterostructures were investigated by UV-Vis, FTIR and current-voltage ( I- V) measurements. For the heterostructure fabricated on IZO treated in oxygen plasma, an improvement in the current value with at least one order of magnitude was evidenced in the I- V characteristics recorded in dark conditions. Also, an increase in the current value for the heterostructure deposited on untreated IZO layer can be achieved by adding an organic layer such as tris-8-hydroxyquinoline aluminium (Alq3).

Therapeutic targeting of oxygen-sensing prolyl hydroxylases abrogates ATF4-dependent neuronal death and improves outcomes after brain hemorrhage in several rodent models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karuppagounder, Saravanan S.; Alim, Ishraq; Khim, Soah J.

Disability or death due to intracerebral hemorrhage (ICH) is attributed to blood lysis, liberation of iron and consequent oxidative stress. Iron chelators bind to free iron and prevent neuronal death induced by oxidative stress and disability due to ICH, but the mechanisms for this effect remain unclear. Here we show that the hypoxia-inducible factor prolyl-hydroxylase (HIF- PHD) family of iron-dependent oxygen sensing enzymes are effectors of iron chelation. Molecular reduction of the three HIF-PHD enzyme isoforms in mouse striatum improved functional recovery following ICH. A low molecular weight hydroxyquinoline inhibitor of the HIF-PHDs, adaptaquin, reduced neuronal death and behavioral deficitsmore » following ICH in several rodent models without affecting total iron or zinc distribution in the brain. Unexpectedly, protection from oxidative death in vitro or from ICH in vivo by adaptaquin was associated with suppression of expression of the prodeath factor ATF4 rather than activation of a HIF-dependent prosurvival pathway. In conclusion, together these findings demonstrate that brain-specific inactivation of the HIF-PHD metalloenzymes with the blood-brain barrier permeable inhibitor adaptaquin can improve functional outcomes following ICH in multiple rodent species.« less

Effects of intracellular iron overload on cell death and identification of potent cell death inhibitors.

PubMed

Fang, Shenglin; Yu, Xiaonan; Ding, Haoxuan; Han, Jianan; Feng, Jie

2018-06-11

Iron overload causes many diseases, while the underlying etiologies of these diseases are unclear. Cell death processes including apoptosis, necroptosis, cyclophilin D-(CypD)-dependent necrosis and a recently described additional form of regulated cell death called ferroptosis, are dependent on iron or iron-dependent reactive oxygen species (ROS). However, whether the accumulation of intracellular iron itself induces ferroptosis or other forms of cell death is largely elusive. In present study, we study the role of intracellular iron overload itself-induced cell death mechanisms by using ferric ammonium citrate (FAC) and a membrane-permeable Ferric 8-hydroxyquinoline complex (Fe-8HQ) respectively. We show that FAC-induced intracellular iron overload causes ferroptosis. We also identify 3-phosphoinositide-dependent kinase 1 (PDK1) inhibitor GSK2334470 as a potent ferroptosis inhibitor. Whereas, Fe-8HQ-induced intracellular iron overload causes unregulated necrosis, but partially activates PARP-1 dependent parthanatos. Interestingly, we identify many phenolic compounds as potent inhibitors of Fe-8HQ-induced cell death. In conclusion, intracellular iron overload-induced cell death form might be dependent on the intracellular iron accumulation rate, newly identified cell death inhibitors in our study that target ferroptosis and unregulated oxidative cell death represent potential therapeutic strategies against iron overload related diseases. Copyright © 2018 Elsevier Inc. All rights reserved.

Luminescence of five-coordinated nickel(ii) complexes with substituted-8-hydroxyquinolines and macrocyclic ligands.

PubMed

Santana, M Dolores; García-Bueno, Rocío; García, Gabriel; Pérez, José; García, Luis; Monge, Miguel; Laguna, Antonio

2010-02-21

A series of heteroleptic quinolinolate pentacoordinated nickel(ii) complexes, [Ni(mcN(3))(R(1),R(2),R(3)-8-hq)](PF(6)), were synthesized and characterized by spectroscopic methods. Single-crystal X-ray diffraction studies for [(Me(3)-mcN(3))Ni(N,O-2-CN-8-hq)][PF(6)] (6a), [(Me(4)-mcN(3))Ni(N,O-8-hq)][PF(6)] (2b) and [(Me(4)-mcN(3))Ni(N,O-5,7-I(2)-8-hq)][PF(6)] (5b) indicate that these complexes consist of a square-pyramidal ligand arrangement containing one chelating quinolinolate and one macrocyclic ligand (mcN(3)). Variation of the substituents on quinolinolate ligands imposes obvious electronic or structural effects on the nickel atom. These chromophores absorb moderately in the visible region and emit in the yellowish-green spectral region from a quinolinolate-centered intraligand charge-transfer excited state. The emission maxima are in the range 520-548 nm, with quantum yields between 0.11 and 1.63%, in deoxygenated organic solvents at room temperature. TD-DFT calculations allow exploration of the photophysical properties of complex [(Me(4)-mcN(3))Ni(N,O-8-hq)][PF(6)] and reveal the influence of the quinolinolate ligand on the HOMO/LUMO energies and oscillator strengths.

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)

The Agr quorum-sensing system regulates fibronectin binding but not hemolysis in the absence of a functional electron transport chain.

PubMed

Pader, Vera; James, Ellen H; Painter, Kimberley L; Wigneshweraraj, Sivaramesh; Edwards, Andrew M

2014-10-01

Staphylococcus aureus is responsible for numerous chronic and recurrent infections, which are frequently associated with the emergence of small-colony variants (SCVs) that lack a functional electron transport chain. SCVs exhibit enhanced expression of fibronectin-binding protein (FnBP) and greatly reduced hemolysin production, although the basis for this is unclear. One hypothesis is that these phenotypes are a consequence of the reduced Agr activity of SCVs, while an alternative is that the lack of a functional electron transport chain and the resulting reduction in ATP production are responsible. Disruption of the electron transport chain of S. aureus genetically (hemB and menD) or chemically, using 2-n-heptyl-4-hydroxyquinoline N-oxide (HQNO), inhibited both growth and Agr activity and conferred an SCV phenotype. Supplementation of the culture medium with synthetic autoinducing peptide (sAIP) significantly increased Agr expression in both hemB mutant strains and S. aureus grown with HQNO and significantly reduced staphylococcal adhesion to fibronectin. However, sAIP did not promote hemolysin expression in hemB mutant strains or S. aureus grown with HQNO. Therefore, while Agr regulates fibronectin binding in SCVs, it cannot promote hemolysin production in the absence of a functional electron transport chain. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Molecular Signature of Pseudomonas aeruginosa with Simultaneous Nanomolar Detection of Quorum Sensing Signaling Molecules at a Boron-Doped Diamond Electrode

PubMed Central

Buzid, Alyah; Shang, Fengjun; Reen, F. Jerry; Muimhneacháin, Eoin Ó; Clarke, Sarah L.; Zhou, Lin; Luong, John H. T.; O’Gara, Fergal; McGlacken, Gerard P.; Glennon, Jeremy D.

2016-01-01

Electroanalysis was performed using a boron-doped diamond (BDD) electrode for the simultaneous detection of 2-heptyl-3-hydroxy-4-quinolone (PQS), 2-heptyl-4-hydroxyquinoline (HHQ) and pyocyanin (PYO). PQS and its precursor HHQ are two important signal molecules produced by Pseudomonas aeruginosa, while PYO is a redox active toxin involved in virulence and pathogenesis. This Gram-negative and opportunistic human pathogen is associated with a hospital-acquired infection particularly in patients with compromised immunity and is the primary cause of morbidity and mortality in cystic fibrosis (CF) patients. Early detection is crucial in the clinical management of this pathogen, with established infections entering a biofilm lifestyle that is refractory to conventional antibiotic therapies. Herein, a detection procedure was optimized and proven for the simultaneous detection of PYO, HHQ and PQS in standard mixtures, biological samples, and P. aeruginosa spiked CF sputum samples with remarkable sensitivity, down to nanomolar levels. Differential pulse voltammetry (DPV) scans were also applicable for monitoring the production of PYO, HHQ and PQS in P. aeruginosa PA14 over 8 h of cultivation. The simultaneous detection of these three compounds represents a molecular signature specific to this pathogen. PMID:27427496

The Agr Quorum-Sensing System Regulates Fibronectin Binding but Not Hemolysis in the Absence of a Functional Electron Transport Chain

PubMed Central

Pader, Vera; James, Ellen H.; Painter, Kimberley L.; Wigneshweraraj, Sivaramesh

2014-01-01

Staphylococcus aureus is responsible for numerous chronic and recurrent infections, which are frequently associated with the emergence of small-colony variants (SCVs) that lack a functional electron transport chain. SCVs exhibit enhanced expression of fibronectin-binding protein (FnBP) and greatly reduced hemolysin production, although the basis for this is unclear. One hypothesis is that these phenotypes are a consequence of the reduced Agr activity of SCVs, while an alternative is that the lack of a functional electron transport chain and the resulting reduction in ATP production are responsible. Disruption of the electron transport chain of S. aureus genetically (hemB and menD) or chemically, using 2-n-heptyl-4-hydroxyquinoline N-oxide (HQNO), inhibited both growth and Agr activity and conferred an SCV phenotype. Supplementation of the culture medium with synthetic autoinducing peptide (sAIP) significantly increased Agr expression in both hemB mutant strains and S. aureus grown with HQNO and significantly reduced staphylococcal adhesion to fibronectin. However, sAIP did not promote hemolysin expression in hemB mutant strains or S. aureus grown with HQNO. Therefore, while Agr regulates fibronectin binding in SCVs, it cannot promote hemolysin production in the absence of a functional electron transport chain. PMID:25092909

Electrochemical oxidation of quinoline aqueous solution on β-PbO2 anode and the evolution of phytotoxicity on duckweed.

PubMed

Ma, Xiangjuan; Bian, Lixia; Ding, Jingfeng; Wu, Yaping; Xia, Huilong; Li, Jionghui

2017-04-01

Electrochemical oxidation of quinoline on a β-PbO 2 electrode modified with fluoride resin and the comprehensive toxicity of intermediates formed during oxidation on duckweed were investigated in detail. The results showed that quinoline was initially hydroxylated at the C-2 and C-8 positions by hydroxyl radicals (·OH) electro-generated on a β-PbO 2 anode, yielding 2(1H)-quinolinone and 8-hydroxyquinoline, then undergoing ring cleavage to form pyridine, nicotinic acid, pyridine-2-carboxaldehyde and acetophenone, which were ultimately converted to biodegradable organic acids. NO 3 - was the final form of quinoline-N. The growth of duckweed exposed to the oxidized quinoline solution was gradually inhibited with the decrease in pH and the formation of intermediates. However, the growth inhibition of duckweed could be eliminated beyond 120 min of oxidation, indicating the comprehensive toxicity of the quinoline solution reduced when the amount of quinoline removed was above 80%. Additionally, the adjustment of the pH to 7.5 and the addition of nutrients to the treated quinoline solution before culturing duckweed could obviously alleviate the inhibition on duckweed. Thus, partial electrochemical degradation of quinoline offers a cost-effective and clean alternative for pretreatment of wastewater containing nitrogen-heterocyclic compounds before biological treatment. The duckweed test presents a simple method for assessing the comprehensive toxicity of intermediates.

Label-free molecular imaging of bacterial communities of the opportunistic pathogen Pseudomonas aeruginosa

NASA Astrophysics Data System (ADS)

Baig, Nameera; Polisetti, Sneha; Morales-Soto, Nydia; Dunham, Sage J. B.; Sweedler, Jonathan V.; Shrout, Joshua D.; Bohn, Paul W.

2016-09-01

Biofilms, such as those formed by the opportunistic human pathogen Pseudomonas aeruginosa are complex, matrix enclosed, and surface-associated communities of cells. Bacteria that are part of a biofilm community are much more resistant to antibiotics and the host immune response than their free-floating counterparts. P. aeruginosa biofilms are associated with persistent and chronic infections in diseases such as cystic fibrosis and HIV-AIDS. P. aeruginosa synthesizes and secretes signaling molecules such as the Pseudomonas quinolone signal (PQS) which are implicated in quorum sensing (QS), where bacteria regulate gene expression based on population density. Processes such as biofilms formation and virulence are regulated by QS. This manuscript describes the powerful molecular imaging capabilities of confocal Raman microscopy (CRM) and surface enhanced Raman spectroscopy (SERS) in conjunction with multivariate statistical tools such as principal component analysis (PCA) for studying the spatiotemporal distribution of signaling molecules, secondary metabolites and virulence factors in biofilm communities of P. aeruginosa. Our observations reveal that the laboratory strain PAO1C synthesizes and secretes 2-alkyl-4-hydroxyquinoline N-oxides and 2-alkyl-4-hydroxyquinolones in high abundance, while the isogenic acyl homoserine lactone QS-deficient mutant (ΔlasIΔrhlI) strain produces predominantly 2-alkyl-quinolones during biofilm formation. This study underscores the use of CRM, along with traditional biological tools such as genetics, for studying the behavior of microbial communities at the molecular level.

Bacterial dissimilatory reduction of arsenic(V) to arsenic(III) in anoxic sediments

USGS Publications Warehouse

Dowdle, P.R.; Laverman, A.M.; Oremland, R.S.

1996-01-01

Incubation of anoxic salt marsh sediment slurries with 10 mM As(V) resulted in the disappearance over time of the As(V) in conjunction with its recovery as As(III). No As(V) reduction to As(III) occurred in heat- sterilized or formalin-killed controls or in live sediments incubated in air. The rate of As(V) reduction in slurries was enhanced by addition of the electron donor lactate, H2, or glucose, whereas the respiratory inhibitor/uncoupler dinitrophenol, rotenone, or 2-heptyl-4-hydroxyquinoline N-oxide blocked As(V) reduction. As(V) reduction was also inhibited by tungstate but not by molybdate, sulfate, or phosphate. Nitrate inhibited As(V) reduction by its action as a preferred respiratory electron acceptor rather than as a structural analog of As(V). Nitrate-respiring sediments could reduce As(V) to As(III) once all the nitrate was removed. Chloramphenicol blocked the reduction of As(V) to As(III) in nitrate- respiring sediments, suggesting that nitrate and arsenate were reduced by separate enzyme systems. Oxidation of [2-14C]acetate to 14CO2 by salt marsh and freshwater sediments was coupled to As(V). Collectively, these results show that reduction of As(V) in sediments proceeds by a dissimilatory process. Bacterial sulfate reduction was completely inhibited by As(V) as well as by As(III).

Addressing the efficiency roll-off in a fluorescent OLED by facile electron transport layer doping and carrier confinement

NASA Astrophysics Data System (ADS)

Soman, Anjaly; M, Manuraj; Unni, K. N. Narayanan

2018-05-01

Organic light emitting diodes (OLEDs) often face the issue of decreasing power efficiency with increasing brightness. Loss of charge carrier balance is one of the factors contributing to the efficiency roll-off. We demonstrate that by using a combination of doped electron transport layer (ETL) and a specially chosen electron blocking layer (EBL) having high hole mobility, this efficiency roll-off can be effectively suppressed. A tris-(8-hydroxyquinoline) aluminium (Alq3) based OLED has been fabricated with 2,3,6,7-Tetrahydro-1,1,7,7,-tetramethyl-1H, 5H,11H-10-(2-benzothiazolyl) quinolizino-[9,9a, 1n gh]coumarin (C545T) as the emissive dopant. Bulk doping of the ETL with lithium fluoride (LiF) was optimized to increase the luminous intensity as well as the current efficiency. An EBL with high hole mobility introduced between the EML and the hole transport layer (HTL) improved the performance drastically, and the device brightness at 9 V got improved by a factor of 2.5 compared to that of the control device. While increasing the brightness from 100 cd/m2 to 1000 cd/m2, the power efficiency drop was 47% for the control device whereas only a drop of 15% was observed for the modified device. The possible mechanisms for the enhanced performance are discussed.

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).

Uncertainty Estimation for the Determination of Ni, Pb and Al in Natural Water Samples by SPE-ICP-OES

NASA Astrophysics Data System (ADS)

Ghorbani, A.; Farahani, M. Mahmoodi; Rabbani, M.; Aflaki, F.; Waqifhosain, Syed

2008-01-01

In this paper we propose uncertainty estimation for the analytical results we obtained from determination of Ni, Pb and Al by solidphase extraction and inductively coupled plasma optical emission spectrometry (SPE-ICP-OES). The procedure is based on the retention of analytes in the form of 8-hydroxyquinoline (8-HQ) complexes on a mini column of XAD-4 resin and subsequent elution with nitric acid. The influence of various analytical parameters including the amount of solid phase, pH, elution factors (concentration and volume of eluting solution), volume of sample solution, and amount of ligand on the extraction efficiency of analytes was investigated. To estimate the uncertainty of analytical result obtained, we propose assessing trueness by employing spiked sample. Two types of bias are calculated in the assessment of trueness: a proportional bias and a constant bias. We applied Nested design for calculating proportional bias and Youden method to calculate the constant bias. The results we obtained for proportional bias are calculated from spiked samples. In this case, the concentration found is plotted against the concentration added and the slop of standard addition curve is an estimate of the method recovery. Estimated method of average recovery in Karaj river water is: (1.004±0.0085) for Ni, (0.999±0.010) for Pb and (0.987±0.008) for Al.

Effect of encapsulation technology on organic light emitting diode lifetime

NASA Astrophysics Data System (ADS)

Zhong, Jian; Gao, Zhuo; Gao, Juan; Dai, Ke; Chen, Jiule

2012-03-01

A kind of green organic light-emitting diodes (OLED) was prepared via vacuum thermal evaporation, of which the multilayer structure was indium-tin oxide (ITO)/copper-phthalocyanine (CuPc) (200 Å)/ N,N'-bis(1-naphthyl)- N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine ( α-NPD) (600 Å)/ N'-diphenyl- N,N'-tris(8-hydroxyquinoline) aluminium (Alq3) (400 Å):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 (200 Å)/LiF (10 Å)/Al (1000 Å). And we used both traditional glass encapsulation and thin film encapsulation (TFE) technologies to protect the device, reducing impact of vapor and oxygen. Organic film offered an excellent surface morphology, while inorganic film was nearly a perfect barrier to vapor and oxygen. Both of them constituted the encapsulation unit of TFE. According to the results of acceleration life test, the operation lifetime of device using TFE was 22% less than that of device using traditional glass cap encapsulation. So, the technology of TFE should be optimized further, and the quality of TFE needs a great improvement. There is a long way to go and a lot of hard work before realizing flexible display with OLED, but the dream will be true one day.

Numerical study of the light output intensity of the bilayer organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Lu, Feiping

2017-02-01

The structure of organic light-emitting diodes (OLEDs) is one of most important issues that influence the light output intensity (LOI) of OLEDs. In this paper, based on a simple but accurate optical model, the influences of hole and electron transport layer thickness on the LOI of bilayer OLEDs, which with N,N0- bis(naphthalen-1-yl)-N,N0- bis(phenyl)- benzidine (NPB) or N,N'- diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4-diamine (TPD) as hole transport layer, with tris(8-hydroxyquinoline) aluminum (Alq3) as electron transport and light emitting layers, were investigated. The laws of LOI for OLEDs under different organic layer thickness values were obtained. The results show that the LOI of devices varies in accordance with damped cosine or sine function as the increasing of organic layer thickness, and the results show that the bilayer OLEDs with the structure of Glass/ITO/NPB (55 nm)/Alq3 (75 nm)/Al and Glass/ITO/TPB (60 nm)/Alq3 (75 nm)/Al have most largest LOI. When the thickness of Alq3 is less than 105 nm, the OLEDs with TPD as hole transport layer have larger LOI than that with NPB as hole transport layer. The results obtained in this paper can present an in-depth understanding of the working mechanism of OLEDs and help ones fabricate high efficiency OLEDs.

Statistical Paradigm for Organic Optoelectronic Devices: Normal Force Testing for Adhesion of Organic Photovoltaics and Organic Light-Emitting Diodes.

PubMed

Vasilak, Lindsay; Tanu Halim, Silvie M; Das Gupta, Hrishikesh; Yang, Juan; Kamperman, Marleen; Turak, Ayse

2017-04-19

In this study, we assess the utility of a normal force (pull-test) approach to measuring adhesion in organic solar cells and organic light-emitting diodes. This approach is a simple and practical method of monitoring the impact of systematic changes in materials, processing conditions, or environmental exposure on interfacial strength and electrode delamination. The ease of measurement enables a statistical description with numerous samples, variant geometry, and minimal preparation. After examining over 70 samples, using the Weibull modulus and the characteristic breaking strength as metrics, we were able to successfully differentiate the adhesion values between 8-tris(hydroxyquinoline aluminum) (Alq 3 ) and poly(3-hexyl-thiophene) and [6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) interfaces with Al and between two annealing times for the bulk heterojunction polymer blends. Additionally, the Weibull modulus, a relative measure of the range of flaw sizes at the fracture plane, can be correlated with the roughness of the organic surface. Finite element modeling of the delamination process suggests that the out-of-plane elastic modulus for Alq 3 is lower than the reported in-plane elastic values. We suggest a statistical treatment of a large volume of tests be part of the standard protocol for investigating adhesion to accommodate the unavoidable variability in morphology and interfacial structure found in most organic devices.

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.

Influence of reagents reacting with metal, thiol and amino sites of catalytic activity and l-phenylalanine inhibition of rat intestinal alkaline phosphatase

PubMed Central

Fishman, William H.; Ghosh, Nimai K.

1967-01-01

1. Studies on the inactivation of rat intestinal alkaline phosphatase by several metal-binding agents, namely EDTA, 8-hydroxyquinoline, pyridine-2,6-dicarboxylic acid, αα′-bipyridyl, o-phenanthroline and sodium cyanide, indicated the functional role of a metal, probably zinc, in the catalysis. The metal ligands lowered stereospecific uncompetitive inhibition of the enzyme by l-phenylalanine by an extent that paralleled the decline in enzyme activity. 2. The thiol reagents p-hydroxymercuribenzoate, iodoacetamide and iodine inactivated rat intestinal phosphatase. The enzyme could be protected from inactivation by either cysteine or substrate. The l-phenylalanine inhibition remained unchanged only in the presence of moderately inactivating concentrations of the thiol reagents. 3. Inactivation of the enzyme by the amino-group-blocking reagent, O-methylisourea, provided ample evidence for the participation in the catalysis of the ∈-amino group of lysine. At the same time, l-phenylalanine inhibition remained unaltered even when the enzyme was strongly inactivated. This ∈-amino-group-blocked enzyme exhibited no change in migration in starch gel, in contrast with enzyme treated with acetic anhydride, formaldehyde or succinic anhydride. The Michaelis constant of the enzyme was enhanced by such modifications, but the optimum pH remained the same. 4. d-Phenylalanine acted as a competitive or `co-operative' activator for intestinal alkaline phosphatase after it had been modified by acetylation. PMID:16742542

A homogeneous cell-based assay for measurement of endogenous paraoxonase 1 activity.

PubMed

Ahmad, Syed; Carter, Jade J; Scott, John E

2010-05-01

Paraoxonase 1 (PON1) is a high-density lipoprotein-associated enzyme that plays an important role in organophosphate detoxification and prevention of atherosclerosis. Thus, there is significant interest in identifying nutritional and pharmacological enhancers of PON1 activity. To identify such compounds, we developed a rapid homogeneous assay to detect endogenous cell-associated PON1 activity. PON1 activity was measured by the simple addition of fluorigenic PON1 substrate DEPFMU to live Huh7 cells in medium and monitoring change in fluorescence. A specific PON1 inhibitor, 2-hydroxyquinoline, was used to confirm that the observed activity was due to PON1. The assay was optimized and characterized with regard to time course, substrate and sodium chloride concentration, number of cells, and tolerance to dimethyl sulfoxide and serum. Aspirin, quercetin, and simvastatin are compounds reported to increase PON1 expression. Consistent with the literature and Western blot data, these compounds enhanced PON1 activity in this assay with comparable efficacies and potencies. A known toxic compound did not increase assay signal. This assay method also detected PON1 activity in normal hepatocytes. Thus, a novel homogeneous assay for detection of endogenous PON1 expression has been developed and is amenable to high-throughput screening for the identification of small molecules that enhance PON1 expression. 2010 Elsevier Inc. All rights reserved.

Inhibition of the sodium-translocating NADH-ubiquinone oxidoreductase [Na+-NQR] decreases cholera toxin production in Vibrio cholerae O1 at the late exponential growth phase

PubMed Central

Minato, Yusuke; Fassio, Sara R.; Reddekopp, Rylan L.; Häse, Claudia C.

2014-01-01

Two virulence factors produced by Vibrio cholerae, cholera toxin (CT) and toxin-corregulated pilus (TCP), are indispensable for cholera infection. ToxT is the central regulatory protein involved in activation of CT and TCP expression. We previously reported that lack of a respiration-linked sodium-translocating NADH–ubiquinone oxidoreductase (Na+-NQR) significantly increases toxT transcription. In this study, we further characterized this link and found that Na+-NQR affects toxT expression only at the early-log growth phase, whereas lack of Na+-NQR decreases CT production after the mid-log growth phase. Such decreased CT production was independent of toxT and ctxB transcription. Supplementing a respiratory substrate, L-lactate, into the growth media restored CT production in the nqrA-F mutant, suggesting that decreased CT production in the Na+-NQR mutant is dependent on electron transport chain (ETC) activity. This notion was supported by the observations that two chemical inhibitors, a Na+-NQR specific inhibitor 2-n-Heptyl-4-hydroxyquinoline N-oxide (HQNO) and a succinate dehydrogenase (SDH) inhibitor, thenoyltrifluoroacetone (TTFA), strongly inhibited CT production in both classical and El Tor biotype strains of V. cholerae. Accordingly, we propose the main respiratory enzyme of V. cholerae, as a potential drug target to treat cholera because human mitochondria do not contain Na+-NQR orthologs. PMID:24361395

Quantitative determination of a synthetic amide derivative of gallic acid, SG-HQ2, using liquid chromatography tandem mass spectrometry, and its pharmacokinetics in rats.

PubMed

Seo, Seung-Yong; Kang, Wonku

2016-11-30

An amide derivative of gallic acid (GA), 3,4,5-trihydroxy-N-(8-hydroxyquinolin-2-yl)benzamide) (SG-HQ2) was recently synthesized, and its inhibitory actions were previously shown on histamine release and pro-inflammatory cytokine expression. In this study, a simultaneous quantification method was developed for the determination of SG-HQ2 and its possible metabolite, GA, in rat plasma using liquid chromatography with a tandem mass spectrometry (LC-MS/MS). After simple protein precipitation with acetonitrile including diclofenac (internal standard, IS), the analytes were chromatographed on a reversed phased column with a mobile phase of acetonitrile and water (60:40, v/v, including 0.1% formic acid). The ion transitions of the precursor to the product ion were principally protonated ion [M+H] + at m/z 313.2→160.6 for SG-HQ2, and deprotonated ions [M-H] - at m/z 168.7→124.9 for GA and 296.0→251.6 for the IS. The accuracy and precision of the assay were in accordance with FDA regulations for the validation of bioanalytical methods. This method was successfully applied to a pharmacokinetic study of SG-HQ2 after intravenous administration in rats. Copyright © 2016 Elsevier B.V. All rights reserved.

Mechanisms of iron regulation of luminescence in Vibrio fischeri.

PubMed Central

Haygood, M G; Nealson, K H

1985-01-01

Synthesis of luciferase (an autoinducible enzyme) is repressed by iron in the symbiotic bioluminescent bacterium Vibrio fischeri. Possible mechanisms of iron regulation of luciferase synthesis were tested with V. fischeri and with Escherichia coli clones containing plasmids carrying V. fischeri luminescence genes. Experiments were conducted in complete medium with and without the synthetic iron chelator ethylenediamine-di(o-hydroxyphenyl acetic acid). Comparison of the effect of ethylenediamine-di(o-hydroxyphenyl acetic acid) and another growth inhibitor, (2-n-heptyl-4-hydroxyquinoline-N-oxide), showed that iron repression is not due to inhibition of growth. A quantitative bioassay for autoinducer was developed with E. coli HB101 containing pJE411, a plasmid carrying V. fischeri luminescence genes with a transcriptional fusion between luxI and E. coli lacZ. Bioassay experiments showed no effect of iron on either autoinducer activity or production (before induction) or transcription of the lux operon. Ethylenediamine-di(o-hydroxyphenyl acetic acid) did not affect luciferase induction in E. coli strains with wild-type iron assimilation (ED8654) or impaired iron assimilation (RW193) bearing pJE202 (a plasmid with functional V. fischeri lux genes), suggesting that the genes responsible for the iron effect are missing or substituted in these clones. Two models are consistent with the data: (i) iron represses autoinducer transport, and (ii) iron acts through an autoinduction-independent regulatory system (e.g., an iron repressor). PMID:3920202

[Study on the determination of trace Cu and Mn in foodstuff preconcentration by precipitate flotation and FAAS].

PubMed

Li, Chun-xiang; Chen, Ting-yu; Yan, Yong-sheng

2007-10-01

In the present paper, the use of 8-hydroxyquinoline(oxine, HQ) complexs in precipitate flotation to separate and preconcentrate Cu and Mn, using SDBS as collector, followed by AAS spectrophotometric determination is proposed. The optimum conditions of precipitate flotation were studied. The effects of several parameters of flotation processes condition on single metal ions precipitation-flotation and multi-metal ions coprecipitation-flotation of Cu and Mn at pH 9 were investigated. The experimental results show that the flotation rate of Cu is supreme with pH 9. Under the condition of pH 9 and changing the ratio of concentration, when Mn/Cu> or =8, the recovery rate of Cu is less than 90%. This method is simple, rapid, accurate, sensitive and precise and avoids using the virulent organic solvent. The linear range of Cu is 0.5-5.0 microg x mL(-1) with the correlative coefficient of 0.9996, detection limit of this method was found to be 1.59 x 10(-3) microg x mL(-1), the linear range of Mn is 0.5-5.0 microg x mL(-1) with the correlative coefficient of 0.9987, and the detection limit of this method was found to be 3.52 x 10(-3) microg x mL(-1). The method was applied to the determination of Cu and Mn in foodstuff, and the recovery is 87.6%-100.7%. The result was satisfactory.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xianmin, E-mail: xmzhang@wpi-aimr.tohoku.ac.jp; Mizukami, Shigemi; Ma, Qinli

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 magnetitemore » 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.« less

Iron species determination by task-specific ionic liquid-based in situ solvent formation dispersive liquid-liquid microextraction combined with flame atomic absorption spectrometry.

PubMed

Sadeghi, Susan; Ashoori, Vahid

2017-10-01

The task-specific ionic liquid (TSIL) of 1-ethyl-3-methylimidazolium bromide functionalized with 8-hydroxyquinoline was used as a chelating agent and extracting solvent for dispersive liquid-liquid microextraction and subsequent determination of Fe(III) by flame atomic absorption spectrometry. The in situ solvent formation of TSIL using KPF 6 provided the desired water-immiscible ionic liquid. The total Fe concentration could be determined after pre-oxidation of Fe(II) to Fe(III). Various factors affecting the proposed extraction procedure were optimized. The proposed analytical conditions were: sample pH 5, TSIL amount 0.3% (w/v), KPF 6 amount 0.15% (w/v), anti-sticking 0.1% (w/v) and salt concentration 5% (w/v). Under optimal conditions, the linear dynamic ranges for Fe(III) and total Fe were 20-80 and 20-110 ng mL -1 , respectively, with a detection limit of 6.9 ng mL -1 for Fe(III) and relative standard deviation of 2.2%. The proposed method was successfully applied to the determination of trace Fe(III) in water (underground, tap, refined water and artificial sea water) and beverage (apple, tomato, and tea) samples. The developed method offers advantages such as simplicity, ease of operation, and extraction of Fe(III) from aqueous solutions without the use of organic solvent. It was successfully applied for iron speciation in different real samples. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

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

PubMed

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

2015-01-01

This study represents a new analytical high-performance liquid chromatography-fluorescence detector method for the determination of Al(III) as Al(III) complex with 8-hydroxyquinoline-5-sulfonic acid in a tap water sample and a coke sample. A micellar liquid chromatographic method is proposed for the determination of aluminum metal in the presence of cetyltrimethylammonium bromide, a cationic surfactant (0.05 M) used for the solubilization of the aluminum complex. The influence of pH and ligand concentration on the formation of the complex was studied by adding a small amount of 0.1 M sodium hydroxide. The metal chelate was detected at λEx 410 nm and λEm 510 nm. This method eliminates the need for addition of reagent or organic modifier to the mobile phase. The complex was analyzed using an Ascentis Express C18 column and a mobile phase consisting of acetonitrile, methanol and water (55 : 30 : 15). Under the optimized conditions, the linear range was 1-200 µg L(-1) and the limit of detection was 0.05 µg L(-1). The method showed a good detector response over the range of interest and was successfully applied for the determination of trace Al(III) in canned coke and water samples containing excess of Mg(II), Ca(II) and other matrices. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

PubMed

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

2013-12-15

The cloud point extraction (CPE) of uranyl ions by different kinds of extractants in Triton X-114 (TX-114) micellar solution was investigated upon the addition of ionic liquids (ILs) with various anions, i.e., bromide (Br(-)), tetrafluoroborate (BF4(-)), hexafluorophosphate (PF6(-)) and bis[(trifluoromethyl)sulfonyl]imide (NTf2(-)). A significant increase of the extraction efficiency was found on the addition of NTf2(-) based ILs when using neutral extractant tri-octylphosphine oxide (TOPO), and the extraction efficiency kept high at both nearly neutral and high acidity. However, the CPE with acidic extractants, e.g., bis(2-ethylhexyl) phosphoric acid (HDEHP) and 8-hydroxyquinoline (8-HQ) which are only effective at nearly neutral condition, was not improved by ILs. The results of zeta potential and (19)F NMR measurements indicated that the anion NTf2(-) penetrated into the TX-114 micelles and was enriched in the surfactant-rich phase during the CPE process. Meanwhile, NTf2(-) may act as a counterion in the CPE of UO2(2+) by TOPO. Furthermore, the addition of IL increased the separation factor of UO2(2+) and La(3+), which implied that in the micelle TOPO, NTf2(-) and NO3(-) established a soft template for UO2(2+). Therefore, the combination of CPE and IL provided a supramolecular recognition to concentrate UO2(2+) efficiently and selectively. Copyright © 2013 Elsevier B.V. All rights reserved.

Fabrication and Characterization of Flexible Organic Light Emitting Diodes Based on Transparent Flexible Clay Substrates

NASA Astrophysics Data System (ADS)

Venkatachalam, Shanmugam; Hayashi, Hiromichi; Ebina, Takeo; Nakamura, Takashi; Nanjo, Hiroshi

2013-03-01

In the present work, transparent flexible polymer-doped clay (P-clay) substrates were prepared for flexible organic light emitting diode (OLED) applications. Nanocrystalline indium tin oxide (ITO) thin films were prepared on P-clay substrates by ion-beam sputter deposition method. The structural, optical, and electrical properties of as-prepared ITO/P-clay showed that the as-prepared ITO thin film was amorphous, and the average optical transparency and sheet resistance were around 84% and 56 Ω/square, respectively. The as-prepared ITO/P-clay samples were annealed at 200 and 270 °C for 1 h to improve the optical transparency and electrical conductivity. The average optical transparency was found to be maximum at an annealing temperature of 200 °C. Finally, N,N-bis[(1-naphthyl)-N,N '-diphenyl]-1,1'-biphenyl)-4,4'-diamine (NPB), tris(8-hydroxyquinoline) aluminum (Alq3) thin films, and aluminum (Al) electrode were prepared on ITO/P-clay substrates by thermal evaporation method. The current density-voltage (J-V) characteristic of Al/NPB/ITO/P-clay showed linear Ohmic behaviour. In contrast, J-V characteristic of Al/Alq3/NPB/ITO/P-clay showed non-linear Schottky behaviour. Finally, a very flexible OLED was successfully fabricated on newly fabricated transparent flexible P-clay substrates. The electroluminescence study showed that the emission intensity of light from the flexible OLED device gradually increased with increasing applied voltage.

Transport and recombination in organic light-emitting diodes studied by electrically detected magnetic resonance.

PubMed

Graeff, C F O; Silva, G B; Nüesch, F; Zuppiroli, L

2005-09-01

We have used electrically detected magnetic resonance (EDMR) to study a series of multilayer organic devices based on aluminum (III) 8-hydroxyquinoline (Alq3). These devices were designed to identify the microscopic origin of different spin-dependent processes, i.e. hopping and exciton formation. The EDMR signal in organic light-emitting diodes (OLEDs) based on Alq3 is only observed when the device is electroluminescent and is assigned to spin-dependent exciton formation. It can be decomposed in at least two Gaussians: one with peak-to-peak line (deltaH(PP)) of 1.6 mT and another with deltaH(PP) of 2.0 to 3.4 mT, depending on bias and temperature. The g-factors of the two components are barely distinguishable and close to 2.003. The broad line is attributed to the resonance in Alq3 anions, while the other line is attributed to cationic states. These attributions are supported by line shape and its electrical-field dependence of unipolar Alq3-based diodes, where hopping process related to dication and dianion formation is observed. In these unipolar devices, it is shown that the signal coming from spin-dependent hopping occurs close to organic semiconductor/metal interfaces. The sign of the magnetic-resonance-induced conductivity change is dominated by charge injection rather than charge mobility. Our results indicate that the probability of singlet exciton formation in our OLEDs is smaller than 25%.

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.

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

PubMed

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

2012-10-02

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.

Biotransformation of isofraxetin-6-O-β-d-glucopyranoside by Angelica sinensis (Oliv.) Diels callus.

PubMed

Zhou, Di; Zhang, Yuhua; Jiang, Zhe; Hou, Yue; Jiao, Kun; Yan, Chunyan; Li, Ning

2017-01-15

Isofraxetin-6-O-β-d-glucopyranoside, identified from traditional medicinal herbal Xanthoceras sorbifolia Bunge, has been demonstrated to be a natural neuroinflammatory inhibitor. In order to obtain more derivatives with potential anti-neuroinflammatory effects, biotransformation was carried out. According to the characteristics of coumarin skeleton, suspension cultures of Angelica sinensis (Oliv.) Diels callus (A. sinensis callus) were employed because of the presence of diverse phenylpropanoids biosynthetic enzymes. As a result, 15 products were yielded from the suspension cultures, including a new coumarin: 8'-dehydroxymethyl cleomiscosin A (1), together with 14 known compounds. Their structures were elucidated by extensive spectroscopic analysis. Furthermore, the biotransformed pathways were discussed. Among them, compound 13 was transformed from isofraxetin-6-O-β-d-glucopyranoside, while compounds 1-6, 10-12, 14-15 were derived from the culture medium stimulated by the substrate. The biotransformation processes include hydroxylation, oxidation and esterification. Furthermore, their inhibitory effects on lipopolysaccharide (LPS)-activated nitric oxide (NO) production were evaluated in BV2 microglial cells. It is worth noting that, 1, 1'-methanediylbis(4-methoxybenzene) (3), obtucarbamates A (5), 2-nonyl-4-hydroxyquinoline N-oxide (10) and 1H-indole-3-carbaldehyde (11) exhibited significant inhibitory effect against neuroinflammation with IC 50 values at 1.22, 10.57, 1.02 and 0.76μM respectively, much stronger than that of the positive control minocycline (IC 50 35.82μM). Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

The Conformational Changes Induced by Ubiquinone Binding in the Na+-pumping NADH:Ubiquinone Oxidoreductase (Na+-NQR) Are Kinetically Controlled by Conserved Glycines 140 and 141 of the NqrB Subunit*

PubMed Central

Strickland, Madeleine; Juárez, Oscar; Neehaul, Yashvin; Cook, Darcie A.; Barquera, Blanca; Hellwig, Petra

2014-01-01

Na+-pumping NADH:ubiquinone oxidoreductase (Na+-NQR) is responsible for maintaining a sodium gradient across the inner bacterial membrane. This respiratory enzyme, which couples sodium pumping to the electron transfer between NADH and ubiquinone, is not present in eukaryotes and as such could be a target for antibiotics. In this paper it is shown that the site of ubiquinone reduction is conformationally coupled to the NqrB subunit, which also hosts the final cofactor in the electron transport chain, riboflavin. Previous work showed that mutations in conserved NqrB glycine residues 140 and 141 affect ubiquinone reduction and the proper functioning of the sodium pump. Surprisingly, these mutants did not affect the dissociation constant of ubiquinone or its analog HQNO (2-n-heptyl-4-hydroxyquinoline N-oxide) from Na+-NQR, which indicates that these residues do not participate directly in the ubiquinone binding site but probably control its accessibility. Indeed, redox-induced difference spectroscopy showed that these mutations prevented the conformational change involved in ubiquinone binding but did not modify the signals corresponding to bound ubiquinone. Moreover, data are presented that demonstrate the NqrA subunit is able to bind ubiquinone but with a low non-catalytically relevant affinity. It is also suggested that Na+-NQR contains a single catalytic ubiquinone binding site and a second site that can bind ubiquinone but is not active. PMID:25006248

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. © 2015 American Institute of Chemical Engineers.

Resonant infrared laser deposition of polymer-nanocomposite materials for optoelectronic applications

NASA Astrophysics Data System (ADS)

Park, Hee K.; Schriver, Kenneth E.; Haglund, Richard F.

2011-11-01

Polymers find a number of potentially useful applications in optoelectronic devices. These include both active layers, such as light-emitting polymers and hole-transport layers, and passive layers, such as polymer barrier coatings and light-management films. This paper reports the experimental results for polymer films deposited by resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) and resonant infrared pulsed laser deposition (RIR-PLD) for commercial optoelectronic device applications. In particular, light-management films, such as anti-reflection coatings, require refractive-index engineering of a material. However, refractive indices of polymers fall within a relatively narrow range, leading to major efforts to develop both low- and high-refractive-index polymers. Polymer nanocomposites can expand the range of refractive indices by incorporating low- or high-refractive-index nanoscale materials. RIR-MAPLE is an excellent technique for depositing polymer-nanocomposite films in multilayer structures, which are essential to light-management coatings. In this paper, we report our efforts to engineer the refractive index of a barrier polymer by combining RIR-MAPLE of nanomaterials (for example, high refractive-index TiO2 nanoparticles) and RIR-PLD of host polymer. In addition, we report on the properties of organic and polymer films deposited by RIR-MAPLE and/or RIR-PLD, such as Alq3 [tris(8-hydroxyquinoline) aluminum] and PEDOT:PSS [poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)]. Finally, the challenges and potential for commercializing RIR-MAPLE/PLD, such as industrial scale-up issues, are discussed.

Photophysics and energy transfer studies of Alq3 confined in the voids of nanoporous anodic alumina.

PubMed

Mohammadpour, Arash; Utkin, Ilya; Bodepudi, Srikrishna Chanakya; Kar, Piyush; Fedosejevs, Robert; Pramanik, Sandipan; Shankar, Karthik

2013-04-01

We report on a hierarchical nanoarchitecture wherein distinct chromophores are deterministically placed at two different types of sites in a nanoporous metal oxide framework. One chromophore, namely Tris(8-hydroxyquinoline)aluminium(III) (Alq3), is embedded in the 1-2 nm sized nanovoids of anodic aluminum oxide (AAO) and another chromophore (carboxyfluorescein or pyrenebutyric acid) is anchored in the form of a monolayer to the surface of the walls of the cylindrical nanopores (- 20 nm in diameter) of AAO. We found the luminescence maximum to occur at 492 nm, blueshifted by at least 18 nm from the value in solutions and thin films. The excited state decay of Alq3 molecules in nanovoids was found to be biexponential with a fast component of 338 ps and a slower component of 2.26 ns, different from Alq3 thin films and solutions. Using a combination of steady state and time-resolved luminescence studies, we found that efficient Forster-type resonance energy transfer (FRET) from Alq3 in the nanovoids to the carboxyfluorescein monolayer could be used to pump the emission of surface-bound chromophores. Conversely, the emission of nanovoid-confined Alq3 could be pumped by energy transfer from a pyrenebutyric acid monolayer. Such intra-nanoarchitecture interactions between chromophores deterministically placed in different spatial locations are important in applications such as organic light emitting diodes, chemical sensors, energy transfer fluorescent labels, light harvesting antennas and organic spintronics.

Structural Dynamics in Metal Tris-hydroxyquinolines: Interconversion of Meridianal and Facial Alq3 Isomers

NASA Astrophysics Data System (ADS)

Ferris, Kim; Sapochak, Linda; Burrows, Paul; Rodovsky, Deanna; Marmolejo, Theresa

2004-03-01

While previous work investigating the charge transport properties of Alq3 has indicated that the meridianal (mer) conformation of Alq3 is predominant species, recent work suggesting identification of a facial (fac) form raises again the question of heterogeneity. Electronic structure computations from our group have noted that the energy difference(in parenthesis) between the mer and fac conformations is highly sensitive to basis set description (8.6 kcal/mol//3-21g*/SCF; 6.9 kcal/mol//6-31g*/SCF), electron correlation (6.0 kcal/mol//3-21g*/MP2; 4.7 kcal/mol//6-31g*/MP2), and solvent effects (4.4 kcal/mol/3-21g*/SCF/DMSO). Given these small energy differences, we have conducted a series of Hartree-Fock and first principles electronic structure computations on the interconversion of these structural forms, and will report on the structural and energetic aspects of the transformation. The likely reaction path involves lengthening of the Al-N bond to the point where a pentacoordinate intermediate or transition state would be formed, followed by flipping of the ligand through rotation around the Al-O bond. Following Schmidbauer's earlier work, we note that transformation involving only one ligand will actually lead to a facial isomer. Preliminary characterization of this transition state suggests that the activation energy is approximately 20-25 kcal/mol above the mer conformation. The authors gratefully acknowledge financial support from PNNL Laboratory Directed Research and Development Project and the U.S. Department of Energy, Office of Science, Materials Sciences Division.

CYP3A4 activity in four different animal species liver microsomes using 7-benzyloxyquinoline and HPLC/spectrofluorometric determination.

PubMed

Baririan, Narine; Desager, Jean-Pierre; Petit, Martine; Horsmans, Yves

2006-01-23

Some microplate-based direct assays with different fluorometric substrates have been developed, among which 7-benzyloxyquinoline (BOQ) has demonstrated the highest degree of selectivity for CYP3A subfamily. In our study, we firstly developed and validated an efficient, fast and cheap HPLC/spectrofluorometric analytical method to quantify 7-hydroxyquinoline (BOQ metabolite). Secondly, BOQ oxidation rate (1.95 +/- 0.24 microM/mg protein/min) was compared to that of midazolam (MDZ) (1.4 +/- 0.21 microM/mg protein/min), an other specific CYP3A probe. However, the difference did not reach statistically significance (test of Sign; p = 0.125, two tailed). Thirdly, the potential use of BOQ in other species than the rat (mouse, dog and monkey) was studied. The highest BOQ activity was observed in rat microsomes (3.75 micromol/mg protein/min) with lower P450 content (0.3 nmol/mg protein) compared to other species. Finally, the effect of CYP3A enzymes-selective inhibitor ketoconazole on the dealkylation of BOQ in control and dexamethasone (DM)-treated rat microsomes was studied. Ketoconazole inhibition potency was greater in control (IC(50) approximately 21.6 microM) compared to DM induced (IC(50) approximately 32.3 microM) microsomes. At concentrations greater than that considered to be enzyme-selective (e.g., 10-30 microM), ketoconazole inhibitory activity did not rise significantly, and at the maximal concentration tested (1,000 microM) a nearly similar inhibition (76%) was observed than that at 50 microM concentration (68.2%).

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

PubMed

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

2012-11-15

A dual-cloud point extraction (d-CPE) procedure has been developed for simultaneous pre-concentration and separation of heavy metal ions (Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ion) in water samples by inductively coupled plasma optical emission spectrometry (ICP-OES). The procedure is based on forming complexes of metal ion with 8-hydroxyquinoline (8-HQ) into the as-formed Triton X-114 surfactant rich phase. Instead of direct injection or analysis, the surfactant rich phase containing the complexes was treated by nitric acid, and the detected ions were back extracted again into aqueous phase at the second cloud point extraction stage, and finally determined by ICP-OES. Under the optimum conditions (pH=7.0, Triton X-114=0.05% (w/v), 8-HQ=2.0×10(-4) mol L(-1), HNO3=0.8 mol L(-1)), the detection limits for Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ions were 0.01, 0.04, 0.01, 0.34, 0.05, and 0.04 μg L(-1), respectively. Relative standard deviation (RSD) values for 10 replicates at 100 μg L(-1) were lower than 6.0%. The proposed method could be successfully applied to the determination of Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ion in water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

8-Hydroxyquinoline based push-pull azo dye: Novel colorimetric chemosensor for anion detection

NASA Astrophysics Data System (ADS)

Arslan, Ömer; Aydıner, Burcu; Yalçın, Ergin; Babür, Banu; Seferoğlu, Nurgül; Seferoğlu, Zeynel

2017-12-01

A novel colorimetric chemosensor based on push-pull dye (8HQA) was synthesized and characterized by using IR, 1H/13C NMR and HRMS for the purpose of recognition of anions and cations in DMSO. The absorption maxima of the chemosensor were determined in different solvents. The selectivity and sensitivity of 8HQA to anions were determined with spectrophotometric and 1H NMR titration techniques. The selectivity of 8HQA for studied anions (CN-, F-, Cl-, I-, AcO-, HSO4- and H2PO4-) was determined in DMSO. There is no selectivity between competing anions such as CN-, F- AcO- and H2PO4- at the stoichiometric ratio of 1:1 in UV-vis titrations experiments however, it was observed different color changes upon addition of CN-, F-, AcO- and H2PO4- to the DMSO solution. In addition, the chemosensor showed no colorimetric response for the following anions; Cl-, I- and HSO4- in DMSO. The colorimetric sensing ability of 8HQA was studied in the presence of chloride salts of different cations such as Ca2+, Mg2+, Cu2+, Co2+, Sn2+, Ni2+, Cd2+ and Hg2+. Upon the addition of 4 equiv of each of the cations showed bathochromic shifts except for Ca2+and Cu2+. Interestingly, no selectivity was observed in interaction with metal cations. In addition, the molecular and electronic structures of 8HQA, as well as the molecular complexes of 8HQA, formed with the anions, were obtained theoretically and confirmed by DFT and TD-DFT calculations.

A flexible plasma-treated silver-nanowire electrode for organic light-emitting devices.

PubMed

Li, Jun; Tao, Ye; Chen, Shufen; Li, Huiying; Chen, Ping; Wei, Meng-Zhu; Wang, Hu; Li, Kun; Mazzeo, Marco; Duan, Yu

2017-11-28

Silver nanowires (AgNWs) are a promising candidate to replace indium tin oxide (ITO) as transparent electrode material. However, the loose contact at the junction of the AgNWs and residual surfactant polyvinylpyrrolidone (PVP) increase the sheet resistance of the AgNWs. In this paper, an argon (Ar) plasma treatment method is applied to pristine AgNWs to remove the PVP layer and enhance the contact between AgNWs. By adjusting the processing time, we obtained AgNWs with a sheet resistance of 7.2Ω/□ and a transmittance of 78% at 550 nm. To reduce the surface roughness of the AgNWs, a peel-off process was used to transfer the AgNWs to a flexible NOA63 substrate. Then, an OLED was fabricated with the plasma-treated AgNWs electrode as anode. The highest brightness (27000 cd/m 2 ) and current efficiency (11.8 cd/A) was achieved with a 30 nm thick light emitting layer of tris-(8-hydroxyquinoline) aluminum doped with 1% 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5 H,11H-(1)-benzopyropyrano(6,7-8-I,j)quinolizin-11-one. Compared to thermal annealing, the plasma-treated AgNW film has a lower sheet resistance, a shorter processing time, and a better hole-injection. Our results indicate that plasma treatment is an effective and efficient method to enhance the conductivity of AgNW films, and the plasma-treated AgNW electrode is suitable to manufacture flexible organic optoelectronic devices.

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.

The use of charge extraction by linearly increasing voltage in polar organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Züfle, Simon; Altazin, Stéphane; Hofmann, Alexander; Jäger, Lars; Neukom, Martin T.; Schmidt, Tobias D.; Brütting, Wolfgang; Ruhstaller, Beat

2017-05-01

We demonstrate the application of the CELIV (charge carrier extraction by linearly increasing voltage) technique to bilayer organic light-emitting devices (OLEDs) in order to selectively determine the hole mobility in N,N0-bis(1-naphthyl)-N,N0-diphenyl-1,10-biphenyl-4,40-diamine (α-NPD). In the CELIV technique, mobile charges in the active layer are extracted by applying a negative voltage ramp, leading to a peak superimposed to the measured displacement current whose temporal position is related to the charge carrier mobility. In fully operating devices, however, bipolar carrier transport and recombination complicate the analysis of CELIV transients as well as the assignment of the extracted mobility value to one charge carrier species. This has motivated a new approach of fabricating dedicated metal-insulator-semiconductor (MIS) devices, where the extraction current contains signatures of only one charge carrier type. In this work, we show that the MIS-CELIV concept can be employed in bilayer polar OLEDs as well, which are easy to fabricate using most common electron transport layers (ETLs), like Tris-(8-hydroxyquinoline)aluminum (Alq3). Due to the macroscopic polarization of the ETL, holes are already injected into the hole transport layer below the built-in voltage and accumulate at the internal interface with the ETL. This way, by a standard CELIV experiment only holes will be extracted, allowing us to determine their mobility. The approach can be established as a powerful way of selectively measuring charge mobilities in new materials in a standard device configuration.

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

Copper (II) complexes of bidentate ligands exhibit potent anti-cancer activity regardless of platinum sensitivity status.

PubMed

Wehbe, Mohamed; Lo, Cody; Leung, Ada W Y; Dragowska, Wieslawa H; Ryan, Gemma M; Bally, Marcel B

2017-12-01

Insensitivity to platinum, either through inherent or acquired resistance, is a major clinical problem in the treatment of many solid tumors. Here, we explored the therapeutic potential of diethyldithiocarbamate (DDC), pyrithione (Pyr), plumbagin (Plum), 8-hydroxyquinoline (8-HQ), clioquinol (CQ) copper complexes in a panel of cancer cell lines that differ in their sensitivity to platins (cisplatin/carboplatin) using a high-content imaging system. Our data suggest that the copper complexes were effective against both platinum sensitive (IC 50  ~ 1 μM platinum) and insensitive (IC 50  > 5 μM platinum) cell lines. Furthermore, copper complexes of DDC, Pyr and 8-HQ had greater therapeutic activity compared to the copper-free ligands in all cell lines; whereas the copper-dependent activities of Plum and CQ were cell-line specific. Four of the copper complexes (Cu(DDC) 2 , Cu(Pyr) 2 , Cu(Plum) 2 and Cu(8-HQ) 2 ) showed IC 50 values less than that of cisplatin in all tested cell lines. The complex copper DDC (Cu(DDC) 2 ) was selected for in vivo evaluation due to its low nano-molar range activity in vitro and the availability of an injectable liposomal formulation. Liposomal (Cu(DDC) 2 ) was tested in a fast-growing platinum-resistant A2780-CP ovarian xenograft model and was found to achieve a statistically significant reduction (50%; p < 0.05) in tumour size. This work supports the potential use of copper-based therapeutics to treat cancers that are insensitive to platinum drugs.

Polyaminoquinoline iron chelators for vectorization of antiproliferative agents: design, synthesis, and validation.

PubMed

Corcé, Vincent; Morin, Emmanuelle; Guihéneuf, Solène; Renault, Eric; Renaud, Stéphanie; Cannie, Isabelle; Tripier, Raphaël; Lima, Luís M P; Julienne, Karine; Gouin, Sébastien G; Loréal, Olivier; Deniaud, David; Gaboriau, François

2012-09-19

Iron chelation in tumoral cells has been reported as potentially useful during antitumoral treatment. Our aim was to develop new polyaminoquinoline iron chelators targeting tumoral cells. For this purpose, we designed, synthesized, and evaluated the biological activity of a new generation of iron chelators, which we named Quilamines, based on an 8-hydroxyquinoline (8-HQ) scaffold linked to linear polyamine vectors. These were designed to target tumor cells expressing an overactive polyamine transport system (PTS). A set of Quilamines bearing variable polyamine chains was designed and assessed for their ability to interact with iron. Quilamines were also screened for their cytostatic/cytotoxic effects and their selective uptake by the PTS in the CHO cell line. Our results show that both the 8-HQ moiety and the polyamine part participate in the iron coordination. HQ1-44, the most promising Quilamine identified, presents a homospermidine moiety and was shown to be highly taken up by the PTS and to display an efficient antiproliferative activity that occurred in the micromolar range. In addition, cytotoxicity was only observed at concentrations higher than 100 μM. We also demonstrated the high complexation capacity of HQ1-44 with iron while much weaker complexes were formed with other cations, indicative of a high selectivity. We applied the density functional theory to study the binding energy and the electronic structure of prototypical iron(III)-Quilamine complexes. On the basis of these calculations, Quilamine HQ1-44 is a strong tridentate ligand for iron(III) especially in the form of a 1:2 complex.

Cardiac Light Chain Amyloidosis: The Role of Metal Ions in Oxidative Stress and Mitochondrial Damage.

PubMed

Diomede, Luisa; Romeo, Margherita; Rognoni, Paola; Beeg, Marten; Foray, Claudia; Ghibaudi, Elena; Palladini, Giovanni; Cherny, Robert A; Verga, Laura; Capello, Gian Luca; Perfetti, Vittorio; Fiordaliso, Fabio; Merlini, Giampaolo; Salmona, Mario

2017-09-20

The knowledge of the mechanism underlying the cardiac damage in immunoglobulin light chain (LC) amyloidosis (AL) is essential to develop novel therapies and improve patients' outcome. Although an active role of reactive oxygen species (ROS) in LC-induced cardiotoxicity has already been envisaged, the actual mechanisms behind their generation remain elusive. This study was aimed at further dissecting the action of ROS generated by cardiotoxic LC in vivo and investigating whether transition metal ions are involved in this process. In the absence of reliable vertebrate model of AL, we used the nematode Caenorhabditis elegans, whose pharynx is an "ancestral heart." LC purified from patients with severe cardiac involvement intrinsically generated high levels of ROS and when administered to C. elegans induced ROS production, activation of the DAF-16/forkhead transcription factor (FOXO) pathway, and expression of proteins involved in stress resistance and survival. Profound functional and structural ROS-mediated mitochondrial damage, similar to that observed in amyloid-affected hearts from AL patients, was observed. All these effects were entirely dependent on the presence of metal ions since addition of metal chelator or metal-binding 8-hydroxyquinoline compounds (chelex, PBT2, and clioquinol) permanently blocked the ROS production and prevented the cardiotoxic effects of amyloid LC. Innovation and Conclusion: Our findings identify the key role of metal ions in driving the ROS-mediated toxic effects of LC. This is a novel conceptual advance that paves the way for new pharmacological strategies aimed at not only counteracting but also totally inhibiting the vicious cycle of redox damage. Antioxid. Redox Signal. 27, 567-582.

Identification and biochemical characterization of small-molecule inhibitors of west nile virus serine protease by a high-throughput screen.

PubMed

Mueller, Niklaus H; Pattabiraman, Nagarajan; Ansarah-Sobrinho, Camilo; Viswanathan, Prasanth; Pierson, Theodore C; Padmanabhan, R

2008-09-01

West Nile virus and dengue virus are mosquito-borne flaviviruses that cause a large number of human infections each year. No vaccines or chemotherapeutics are currently available. These viruses encode a serine protease that is essential for polyprotein processing, a required step in the viral replication cycle. In this study, a high-throughput screening assay for the West Nile virus protease was employed to screen approximately 32,000 small-molecule compounds for identification of inhibitors. Lead inhibitor compounds with three distinct core chemical structures (1 to 3) were identified. In a secondary screening of selected compounds, two compounds, belonging to the 8-hydroxyquinoline family (compounds A and B) and containing core structure 1, were identified as potent inhibitors of the West Nile virus protease, with K(i) values of 3.2 +/- 0.3 microM and 3.4 +/- 0.6 microM, respectively. These compounds inhibited the dengue virus type 2 protease with K(i) values of 28.6 +/- 5.1 microM and 30.2 +/- 8.6 microM, respectively, showing some selectivity in the inhibition of these viral proteases. However, the compounds show no inhibition of cellular serine proteases, trypsin, or factor Xa. Kinetic analysis and molecular docking of compound B onto the known crystal structure of the West Nile virus protease indicate that the inhibitor binds in the substrate-binding cleft. Furthermore, compound B was capable of inhibiting West Nile virus RNA replication in cultured Vero cells (50% effective concentration, 1.4 +/- 0.4 microM; selectivity index, 100), presumably by inhibition of polyprotein processing.

Clioquinol and vitamin B12 (cobalamin) synergistically rescue the lead-induced impairments of synaptic plasticity in hippocampal dentate gyrus area of the anesthetized rats in vivo.

PubMed

Chen, W-H; Wang, M; Yu, S-S; Su, L; Zhu, D-M; She, J-Q; Cao, X-J; Ruan, D-Y

2007-07-13

Lead (Pb(2+)) exposure in development induces impairments of synaptic plasticity in the hippocampal dentate gyrus (DG) area of the anesthetized rats in vivo. The common chelating agents have many adverse effects and are incapable of alleviating lead-induced neurotoxicity. Recently, CQ, clioquinol (5-chloro-7-iodo-8-hydroxy-quinoline), which is a transition metal ion chelator and/or ionophore with low affinity for metal ions, has yielded some promising results in animal models and clinical trials related to dysfunctions of metal ions. In addition, CQ-associated side effects are believed to be overcome with vitamin B12 (VB12) supplementation. To determine whether CQ treatment could rescue impairments of synaptic plasticity induced by chronic Pb(2+) exposure, we investigated the input/output functions (I/Os), paired-pulse reactions (PPRs) and long-term potentiation (LTP) of different treatment groups in hippocampal DG area of the anesthetized rat in vivo by recording field potentials and measured hippocampal Pb(2+) concentrations of different treatment groups by PlasmaQuad 3 inductive coupled plasma mass spectroscopy. The results show: CQ alone does not rescue the lead-induced impairments of synaptic plasticity in hippocampal DG area of the anesthetized rats in vivo; VB12 alone partly rescues the lead-induced impairments of LTP; however the co-administration of CQ and VB12 totally rescues these impairments of synaptic plasticity and moreover, the effects of CQ and VB12 co-administration are specific to the lead-exposed animals.

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

Binary and ternary copper(II) complexes of a new Schiff base ligand derived from 4-acetyl-5,6-diphenyl-3(2H)-pyridazinone: Synthesis, spectral, thermal, antimicrobial and antitumor studies

NASA Astrophysics Data System (ADS)

Shebl, Magdy; Adly, Omima M. I.; Abdelrhman, Ebtesam M.; El-Shetary, B. A.

2017-10-01

A new Schiff base ligand was synthesized by the reaction of 4-acetyl-5,6-diphenyl-3(2H)-pyridazinone with ethylenediamine. A series of binary copper(II) Schiff base complexes have been synthesized by using various copper(II) salts; AcO-, NO3-, ClO4-, Cl- and Br-. Ternary complexes were synthesized by using auxiliary ligands (L‧) [N,O-donor; 8-hydroxyquinoline and glycine or N,N-donor; 1,10-phenanthroline, bipyridyl and 2-aminopyridine]. The structures of the Schiff base and its complexes were characterized by elemental and thermal analyses, IR, electronic, mass, 1H NMR and ESR spectra in addition to conductivity and magnetic susceptibility measurements. The obtained complexes include neutral binuclear complexes as well as neutral and cationic mononuclear complexes according to the anion used and the experimental conditions. The ESR spin Hamiltonian parameters of some complexes were calculated and discussed. The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. Kinetic parameters (Ea, A, ΔH, ΔS and ΔG) of the thermal decomposition stages were evaluated using Coats-Redfern equations. The antimicrobial activity of the Schiff base and its complexes was screened against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Salmonella typhimurium and Escherichia coli), yeast (Candida albicans) and fungus (Aspergillus fumigatus). The antitumor activity of the Schiff base and some of its Cu(II) complexes was investigated against HepG-2 cell line.

Neuroprotection by a novel brain permeable iron chelator, VK-28, against 6-hydroxydopamine lession in rats.

PubMed

Shachar, Dorit Ben; Kahana, Nava; Kampel, Vladimir; Warshawsky, Abraham; Youdim, Moussa B H

2004-02-01

Significant increase in iron occurs in the substantia nigra pars compacta of Parkinsonian subjects, and in 6-hydroxydopamine (6-OHDA) treated rats and monkeys. This increase in iron has been attributed to its release from ferritin and is associated with the generation of reactive oxygen species and the onset of oxidative stress-induced neurodegeneration. Several iron chelators with hydroxyquinoline backbone were synthesized and their ability to inhibit basal as well as iron-induced mitochondrial lipid peroxidation was examined. The neuroprotective potential of the brain permeable iron chelator, VK-28 (5-[4-(2-hydroxyethyl) piperazine-1-ylmethyl]-quinoline-8-ol), injected either intraventricularly (ICV) or intraperitoneally (IP), to 6-OHDA lesioned rats was investigated. VK-28 inhibited both basal and Fe/ascorbate induced mitochondrial membrane lipid peroxidation, with an IC(50) (12.7 microM) value comparable to that of the prototype iron chelator, desferal, which does not cross the blood brain barrier. At an ICV pretreatment dose as low as 1 microg, VK-28 was able to completely protect against ICV 6-OHDA (250 microg) induced striatal dopaminergic lesion, as measured by dopamine (DA), dihydroxyphenylacetic acid (DOPAC) and homovanilic acid (HVA) levels. IP injection of rats with VK-28 (1 and 5 mg/kg) daily for 10 and 7 days, respectively, demonstrated significant neuroprotection against ICV 6-OHDA at the higher dose, with 68% protection against loss of dopamine at 5mg/kg dosage of VK-28. The present study is the first to show neuroprotection with a brain permeable iron chelator. The latter can have implications for the treatment of Parkinson's disease and other neurodegenerative diseases (Alzheimer's disease, Friedreich ataxia, aceruloplasminemia, Hallervorden Spatz syndrome) where abnormal iron accumulation in the brain is thought to be associated with the degenerative processes.

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. Copyright © 2015 John Wiley & Sons, Ltd.

Electrochemiluminescence detection of TNT by resonance energy transfer through the formation of a TNT-amine complex.

PubMed

Qi, Wenjing; Xu, Min; Pang, Lei; Liu, Zhongyuan; Zhang, Wei; Majeed, Saadat; Xu, Guobao

2014-04-14

2,4,6-Trinitrotoluene (TNT) is a widely used nitroaromatic explosive with significant detrimental effects on the environment and human health. Its detection is of great importance. In this study, both electrochemiluminescence (ECL)-based detection of TNT through the formation of a TNT-amine complex and the detection of TNT through electrochemiluminescence resonance energy transfer (ECRET) are developed for the first time. 3-Aminopropyltriethoxysilane (APTES)-modified [Ru(phen)3](2+) (phen=1,10-phenanthroline)-doped silica nanoparticles (RuSiNPs) with uniform sizes of (73±3) nm were synthesized. TNT can interact with APTES-modified RuSiNPs through charge transfer from electron-rich amines in the RuSiNPs to the electron-deficient aromatic ring of TNT to form a red TNT-amine complex. The absorption spectrum of this complex overlaps with the ECL spectrum of the APTES-modified RuSiNPs/triethylamine system. As a result, ECL signals of the APTES-modified RuSiNPs/triethylamine system are turned off in the presence of TNT owing to resonance energy transfer from electrochemically excited RuSiNPs to the TNT-amine complex. This ECRET method has been successfully applied for the sensitive determination of TNT with a linear range from 1×10(-9) to 1×10(-6) M with a fast response time within 1 min. The limit of detection is 0.3 nM. The method exhibits good selectivity towards 2,4-dinitrotoluene, p-nitrotoluene, nitrobenzene, phenol, p-quinone, 8-hydroxyquinoline, p-phenylenediamine, K3[Fe(CN)6], Fe(3+), NO3(-), NO2(-), Cr(3+), Fe(2+), Pb(2+), SO3(2-), formaldehyde, oxalate, proline, and glycine. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oxygen consumption in Plasmodium berghei-infected murine red cells: a direct spectrophotometric assay in intact erythrocytes.

PubMed

Deslauriers, R; Moffatt, D J; Smith, I C

1986-05-29

A spectrophotometric assay has been devised to measure oxygen consumption non-invasively in intact murine red cells parasitized by Plasmodium berghei. The method uses oxyhemoglobin in the erythrocytes both as a source of oxygen and as an indicator of oxygen consumption. Spectra of intact cells show broad peaks and sloping baselines due to light-scattering. In order to ascertain the number of varying components in the 370-450 nm range, the resolution of the spectra was enhanced using Fourier transforms of the frequency domain spectra. Calculation of oxygen consumption was carried out for two-component systems (oxyhemoglobin, deoxyhemoglobin) using absorbances at 415 and 431 nm. Samples prepared from highly parasitized mice (greater than 80% parasitemia, 5% hematocrit) showed oxygen consumption rates of (4-8) X 10(-8) microliter/cell per h. This rate was not attributable to the presence of white cells or reticulocytes. The rate of oxygen consumption in the erythrocytes is shown to be modulated by various agents: the respiratory inhibitors NaN3 and KCN (1 mM) reduced oxygen consumption 2-3-fold; salicylhydroxamic acid (2.5 mM) caused a 20% reduction in rate and 10 mM NaN3, completely blocked deoxygenation. Antimalarial drugs and metal-chelating agents were also tested. Chloroquine, EDTA and desferal (desferoxamine mesylate) did not decrease the deoxygenation rate of hemoglobin in parasitized cells. Quinacrine, quinine and primaquine reduced the rate of formation of deoxyhemoglobin but also produced substantial quantities of methemoglobin. The lipophilic chelator, 5-hydroxyquinoline, decreased the rate of deoxygenation one-third. The spectrophotometric assay provides a convenient means to monitor oxygen consumption in parasitized red cells, to test the effects of various agents thereon, and potentially to explore possible mechanisms for oxygen utilization.

5-(2-Aminopropyl)indole (5-IT): a psychoactive substance used for recreational purposes is an inhibitor of human monoamine oxidase (MAO).

PubMed

Herraiz, Tomás; Brandt, Simon D

2014-01-01

5-(2-Aminopropyl)indole (5-IT) is a psychoactive compound that has recently been associated with several fatal and non-fatal intoxications in a number of European countries. There are indications that acute effects may include symptoms of monoaminergic (e.g. serotonin) toxicity and one mechanism involved in the increase of serotonin levels includes the inhibition of monoamine oxidase. This study investigated the effect of 5-IT on human MAO-A and -B isozymes using kynuramine as the substrate. Substrate conversion to 4-hydroxyquinoline was monitored by high-performance liquid chromatography coupled to diode array detection. This method was employed to determine the extent of MAO inhibition (IC50 and Ki ) and it was found that 5-IT was a selective, competitive and reversible inhibitor of MAO-A. 5-IT revealed a relatively potent ability to inhibit MAO-A (IC50  =1.6 μM and Ki  =0.25 μM) while MAO-B inhibition was not observed (0-500 μM 5-IT). Under identical experimental conditions, other established inhibitors of MAO-A and antidepressants provided the following IC50 values: clorgyline 16 nM, harmaline 20 nM, toloxatone 6.7 μM and moclobemide >500 μM. These data indicated that 5-IT was less potent than clorgyline and harmaline but more potent than toloxatone and moclobemide under the in-vitro conditions studied. The inhibition of MAO-A suggests that 5-IT by itself or in combination with other substances may be able to potentiate serotonergic/monoaminergic effects and further studies are needed to clarify its relevance to the adverse effects reported for 5-IT. Copyright © 2013 John Wiley & Sons, Ltd.

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. Copyright © 2015 Elsevier Inc. All rights reserved.

Deferasirox is a powerful NF-κB inhibitor in myelodysplastic cells and in leukemia cell lines acting independently from cell iron deprivation by chelation and reactive oxygen species scavenging

PubMed Central

Messa, Emanuela; Carturan, Sonia; Maffè, Chiara; Pautasso, Marisa; Bracco, Enrico; Roetto, Antonella; Messa, Francesca; Arruga, Francesca; Defilippi, Ilaria; Rosso, Valentina; Zanone, Chiara; Rotolo, Antonia; Greco, Elisabetta; Pellegrino, Rosa M.; Alberti, Daniele; Saglio, Giuseppe; Cilloni, Daniela

2010-01-01

Background Usefulness of iron chelation therapy in myelodysplastic patients is still under debate but many authors suggest its possible role in improving survival of low-risk myelodysplastic patients. Several reports have described an unexpected effect of iron chelators, such as an improvement in hemoglobin levels, in patients affected by myelodysplastic syndromes. Furthermore, the novel chelator deferasirox induces a similar improvement more rapidly. Nuclear factor-κB is a key regulator of many cellular processes and its impaired activity has been described in different myeloid malignancies including myelodysplastic syndromes. Design and Methods We evaluated deferasirox activity on nuclear factor-κB in myelodysplastic syndromes as a possible mechanism involved in hemoglobin improvement during in vivo treatment. Forty peripheral blood samples collected from myelodysplastic syndrome patients were incubated with 50 μM deferasirox for 18h. Results Nuclear factor-κB activity dramatically decreased in samples showing high basal activity as well as in cell lines, whereas no similar behavior was observed with other iron chelators despite a similar reduction in reactive oxygen species levels. Additionally, ferric hydroxyquinoline incubation did not decrease deferasirox activity in K562 cells suggesting the mechanism of action of the drug is independent from cell iron deprivation by chelation. Finally, incubation with both etoposide and deferasirox induced an increase in K562 apoptotic rate. Conclusions Nuclear factor-κB inhibition by deferasirox is not seen from other chelators and is iron and reactive oxygen species scavenging independent. This could explain the hemoglobin improvement after in vivo treatment, such that our hypothesis needs to be validated in further prospective studies. PMID:20534700

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

Single step biotransformation of corn oil phytosterols to boldenone by a newly isolated Pseudomonas aeruginosa.

PubMed

Eisa, Mohamed; El-Refai, Heba; Amin, Magdy

2016-09-01

A new potent Pseudomonas aeruginosa isolate capable for biotransformation of corn oil phytosterol (PS) to 4-androstene-3, 17-dione (AD), testosterone (T) and boldenone (BOL) was identified by phenotypic analysis and 16S rRNA gene sequencing. Sequential statistical strategy was used to optimize the biotransformation process mainly concerning BOL using Factorial design and response surface methodology (RSM). The production of BOL in single step microbial biotransformation from corn oil phytosterols by P. aeruginosa was not previously reported. Results showed that the pH concentration of the medium, (NH 4 ) 2 SO 4 and KH 2 PO 4 were the most significant factors affecting BOL production. By analyzing the statistical model of three-dimensional surface plot, BOL production increased from 36.8% to 42.4% after the first step of optimization, and the overall biotransformation increased to 51.9%. After applying the second step of the sequential statistical strategy BOL production increased to 53.6%, and the overall biotransformation increased to 91.9% using the following optimized medium composition (g/l distilled water) (NH 4 ) 2 SO 4 , 2; KH 2 PO 4 , 4; Na 2 HPO 4 . 1; MgSO 4 ·7H 2 O, 0.3; NaCl, 0.1; CaCl 2 ·2H 2 O, 0.1; FeSO 4 ·7H 2 O, 0.001; ammonium acetate 0.001; Tween 80, 0.05%; corn oil 0.5%; 8-hydroxyquinoline 0.016; pH 8; 200 rpm agitation speed and incubation time 36 h at 30 °C. Validation experiments proved the adequacy and accuracy of model, and the results showed the predicted value agreed well with the experimental values.

Synthesis of Ferrite Nickel Nano-particles and Its Role as a p-Dopant in the Improvement of Hole Injection of an Organic Light-Emitting Diode

NASA Astrophysics Data System (ADS)

Noori, Maryam; Jafari, Mohammad Reza; Hosseini, Sayed Mohsen; Shahedi, Zahra

2017-07-01

We fabricated an organometallic complex based on zinc ions using zinc complex as a fluorescent in organic light-emitting diodes (OLEDs). Also, the nano-particles of ferrite nickel were produced in a simple aqueous system prepared by mixing Ni (NO3)2, Fe (NO3)3 and deionized water solutions. The synthesized zinc bis (8-hydroxyquinoline) (Znq2) complex and NiFe2O4 nano-particles were characterized by using x-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) as well as photoluminescence spectroscopy analysis. Their energy level was also determined by some cyclic voltammetry (CV) measurements. The maximum green photoluminescence was observed at 565 nm. The nano-particles of ferrite nickel were utilized in preparation of OLEDs by blending of the magnetic nano-particles with PEDOT:PSS and Zn-complex solutions. The electrical and optical performance of prepared OLEDs with/without doped nano-particle was studied. The samples were configured into two structures: (1) Indium Tin Oxide (ITO)/ poly(3,4-ethylenedi-oxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/Znq2/(2-4-biphenylyl)-5-phenyl-oxadiazole (PBD)/aluminum (Al) and (2) ITO/PEDOT:PSS:NiFe2O4(NPs)/Znq2/PBD/Al. Obtained results showed that the current density and electroluminescence efficiency were increased and the turn-on voltage decreased (about 3 V) by using nano-particles into a PEDOT:PSS layer (Hole transport layer). Also, the electroluminescence efficiency was decreased by incorporating magnetic nano-particles into a Zn-complex layer (emissive layer). It was found that utilizing NiFe2O4 nano-particles caused an increase of hole-injection layer conductivity effectively and a decrease of the turn-on voltage.

Sulfide-dependent photosynthetic electron flow coupled to proton translocation in thylakoids of the cyanobacterium Oscillatoria limnetica.

PubMed

Shahak, Y; Arieli, B; Binder, B; Padan, E

1987-12-01

Light-induced proton translocation coupled to sulfide-dependent electron transport has been studied in isolated thylakoids of the cyanobacterium Oscillatoria limnetica. The thylakoids are obtained by osmotic shock of washed spheroplasts, prepared with glycine-betaine as the osmotic stabilizer. 13C NMR studies suggests that betaine is the major osmoregulator in O. limnetica. Thylakoid preparations obtained from both sulfide-induced anoxygenic cells and noninduced oxygenic cells are capable of proton pumping coupled to phenazinemethosulfate-mediated cyclic electron flow. However, only in the induced thylakoids can sulfide-dependent proton gradient (delta pH) formation be measured, using either NADP or methyl viologen as the terminal acceptor. Sulfide-dependent delta pH formation correlates with a high-affinity electron donation site (apparent Km 44 microM at pH 7.9). This site is not lost upon washing of the thylakoids. In addition, both sulfide-dependent electron transport and delta pH formation are sensitive to inhibitors of the cytochrome b6f complex such as 2-n-nonyl-4-hydroxyquinoline-N-oxide, 2,4-dinitrophenyl ether of 2-iodo-4-nitrothymol, or stigmatellin. Sulfide-dependent NADP photoreduction of low affinity (which does not saturate by as much as 7 mM sulfide) is detected in both induced and noninduced thylakoids, but this activity is insensitive to the inhibitors and is not coupled to proton transport. It is suggested that the adaptation of O. limnetica to anoxygenic photosynthesis involves the induction of a thylakoid factor(s) which creates a high-affinity site for sulfide, and the transfer of its electrons via the cytochrome b6f complex, coupled to proton translocation.

Utilization of Electrically Reduced Neutral Red by Actinobacillus succinogenes: Physiological Function of Neutral Red in Membrane-Driven Fumarate Reduction and Energy Conservation

PubMed Central

Park, D. H.; Zeikus, J. G.

1999-01-01

Neutral red (NR) functioned as an electronophore or electron channel enabling either cells or membranes purified from Actinobacillus succinogenes to drive electron transfer and proton translocation by coupling fumarate reduction to succinate production. Electrically reduced NR, unlike methyl or benzyl viologen, bound to cell membranes, was not toxic, and chemically reduced NAD. The cell membrane of A. succinogenes contained high levels of benzyl viologen-linked hydrogenase (12.2 U), fumarate reductase (13.1 U), and diaphorase (109.7 U) activities. Fumarate reductase (24.5 U) displayed the highest activity with NR as the electron carrier, whereas hydrogenase (1.1 U) and diaphorase (0.8 U) did not. Proton translocation by whole cells was dependent on either electrically reduced NR or H2 as the electron donor and on the fumarate concentration. During the growth of Actinobacillus on glucose plus electrically reduced NR in an electrochemical bioreactor system versus on glucose alone, electrically reduced NR enhanced glucose consumption, growth, and succinate production by about 20% while it decreased acetate production by about 50%. The rate of fumarate reduction to succinate by purified membranes was twofold higher with electrically reduced NR than with hydrogen as the electron donor. The addition of 2-(n-heptyl)-4-hydroxyquinoline N-oxide to whole cells or purified membranes inhibited succinate production from H2 plus fumarate but not from electrically reduced NR plus fumarate. Thus, NR appears to replace the function of menaquinone in the fumarate reductase complex, and it enables A. succinogenes to utilize electricity as a significant source of metabolic reducing power. PMID:10198002

The effects of ultra-thin cerium fluoride film as the anode buffer layer on the electrical characteristics of organic light emitting diodes

NASA Astrophysics Data System (ADS)

Lu, Hsin-Wei; Tsai, Cheng-Che; Hong, Cheng-Shong; Kao, Po-Ching; Juang, Yung-Der; Chu, Sheng-Yuan

2016-11-01

In this study, the efficiency of organic light-emitting diodes (OLEDs) was enhanced by depositing a CeF3film as an ultra-thin buffer layer between the indium tin oxide (ITO) electrode and α-naphthylphenylbiphenyldiamine (NPB) hole transport layer, with the structure configuration ITO/CeF3 (0.5, 1, and 1.5 nm)/α-naphthylphenylbiphenyl diamine (NPB) (40 nm)/tris(8-hydroxyquinoline) aluminum (Alq3) (60 nm)/lithium fluoride (LiF) (1 nm)/Al (150 nm). The enhancement mechanism was systematically investigated via several approaches. The X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy results revealed the formation of the UV-ozone treated CeF3 film. The work function increased from 4.8 eV (standard ITO electrode) to 5.22 eV (0.5-nm-thick UV-ozone treated CeF3 film deposited on the ITO electrode). The surface roughness of the UV-ozone treated CeF3 film was smoother than that of the standard ITO electrode. Further, the UV-ozone treated CeF3 film increased both the surface energy and polarity, as determined from contact angle measurements. In addition, admittance spectroscopy measurements showed an increased capacitance and conductance of the OLEDs. Accordingly, the turn-on voltage decreased from 4.2 V to 3.6 V at 1 mA/cm2, the luminance increased from 7588 cd/m2 to 24760 cd/m2, and the current efficiency increased from 3.2 cd/A to 3.8 cd/A when the 0.5-nm-thick UV-ozone treated CeF3 film was inserted into the OLEDs.

Solvent-Dependent Delamination, Restacking, and Ferroelectric Behavior in a New Charge-Separated Layered Compound: [NH4 ][Ag3 (C9 H5 NO4 S)2 (C13 H14 N2 )2 ]⋅8 H2 O.

PubMed

Sushrutha, Sringeri Ramesh; Mohana, Shivanna; Pal, Somnath; Natarajan, Srinivasan

2017-01-03

A new anionic coordination polymer, [NH 4 ][Ag 3 (C 9 H 5 NO 4 S) 2 (C 13 H 14 N 2 ) 2 ]⋅8 H 2 O, with a two-dimensional structure, has been synthesized by a reaction between silver nitrate, 8-hydroxyquinoline-5-sulfonic acid (HQS), and 4,4'-trimethylene dipyridine (TMDP). The compound stabilizes in a noncentrosymmetric space group, and the lattice water molecules and the charge-compensating [NH 4 ] + group occupy the inter-lamellar spaces. The lattice water molecules can be fully removed and reinserted, which is accompanied by a crystalline-amorphous-crystalline transformation. This transformation resembles the collapse/delamination and restacking of the layers. To the best of our knowledge, this is the first observation of delamination and restacking in an inorganic coordination polymer that contains silver. The presence of a natural dipole (the anionic framework and cationic ammonium ions) along with the noncentrosymmetric space group gives rise to the room-temperature ferroelectric behavior of the compound. The ferroelectric behavior is also water-dependent and exhibits a ferroelectric-paraelectric transformation. The temperature-dependent dielectric measurements indicate that the ferroelectric/ paraelectric transformation occurs at 320 K. This transformation has also been investigated by using in-situ IR spectroscopy and PXRD studies. The second-harmonic generation (SHG) study indicated values that are comparable to some of the known SHG solids, such as potassium dihydrogen phosphate (KDP) and urea. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spatially-dependent alkyl quinolone signaling responses to antibiotics in Pseudomonas aeruginosa swarms.

PubMed

Morales-Soto, Nydia; Dunham, Sage J B; Baig, Nameera F; Ellis, Joseph F; Madukoma, Chinedu S; Bohn, Paul W; Sweedler, Jonathan V; Shrout, Joshua D

2018-03-27

There is a general lack of understanding about how communities of bacteria respond to exogenous toxins such as antibiotics. Most of our understanding of community-level stress responses comes from the study of stationary biofilm communities. Although several community behaviors and production of specific biomolecules affecting biofilm development and associated behavior have been described for Pseudomonas aeruginosa and other bacteria, we have little appreciation for the production and dispersal of secreted metabolites within the 2D and 3D spaces they occupy as they colonize, spread, and grow on surfaces. Here we specifically studied the phenotypic responses and spatial variability of alkyl quinolones, including the Pseudomonas quinolone signal (PQS) and members of the alkyl hydroxyquinoline (AQNO) subclass, in P. aeruginosa plate-assay swarming communities. We found that PQS production was not a universal signaling response to antibiotics as tobramycin elicited an alkyl quinolone response while carbenicillin did not. We also found that PQS and AQNO profiles in response to tobramycin were markedly distinct and influenced these swarms on different spatial scales. The distribution of alkyl quinolones varied by several orders of magnitude within the same swarm. At some tobramycin exposures, P. aeruginosa swarms produced alkyl quinolones in the range of 150 µM PQS and 400 µM AQNO that accumulated as aggregates. Our collective findings show that the distribution of alkyl quinolones can vary by several orders of magnitude within the same swarming community.  More notably, our results suggest that multiple intercellular signals acting on different spatial scales can be triggered by one common cue. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

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

Seasonal change in the level and the chemical forms of aluminum in soil solution under a Japanese cedar forest.

PubMed

Umemura, Tomonari; Usami, Yosuke; Aizawa, Sho-ichi; Tsunoda, Kin-ichi; Satake, Ken-ichi

2003-12-30

The level of dissolved aluminum and its chemical forms in soil solutions consecutively collected by a porous cup vacuum sampler were monitored over a period from January 2001 to December 2001 at a Japanese cedar (Cryptomeria japonica) forestry area susceptible to acid deposition to characterize current soil dynamics and to evaluate potential tree damages. Distinction and characterization of Al species with differential toxicities were performed by two complementary speciation techniques; cation-exchange HPLC with fluorometric detection using 8-hydroxyquinoline-5-sulfonic acid (HQS) and size-fractionation/inductively coupled plasma atomic emission spectrometry (ICP-AES). The concentrations of free Al (mainly Al3+ and Al(OH)2+) and inert Al (existing as the complexed and/or colloidal forms) ranged between 0-150 microM and 10-50 microM, respectively. The concentrations of inert Al were mostly below 40 microM during an annual cycle and showed no marked seasonal variation, while free Al concentrations showed a clear tendency to increase in the spring and summer seasons (in the period from April to August) probably due to the enhanced activity of microbial nitrification and the resultant soil acidification. Major cations and anions were also regularly determined and their seasonal changes were correlated with that of the dissolved Al concentration. Correlations between total Al (mainly existing as free Al) and the related species (and environmental conditions) were as follows: Al and Mg (R=0.96, P<0.01), Al and Ca (R=0.97, P<0.01), Al and NO3- (R=0.68, P<0.01), Al and temperature (R=0.68, P<0.01), Al and solution pH (R=-0.61, P<0.01), solution pH and NO3- (R=-0.65, P<0.01).

Alternative quinone substrates and inhibitors of human electron-transfer flavoprotein-ubiquinone oxidoreductase.

PubMed Central

Simkovic, Martin; Frerman, Frank E

2004-01-01

Electron-transfer flavoprotein (ETF)-ubiquinone (2,3-dimethoxy-5-methyl-1,4-benzoquinone) oxidoreductase (ETF-QO) is a membrane-bound iron-sulphur flavoprotein that participates in an electron-transport pathway between eleven mitochondrial flavoprotein dehydrogenases and the ubiquinone pool. ETF is the intermediate electron carrier between the dehydrogenases and ETF-QO. The steady-state kinetic constants of human ETF-QO were determined with ubiquinone homologues and analogues that contained saturated n-alkyl substituents at the 6 position. These experiments show that optimal substrates contain a ten-carbon-atom side chain, consistent with a preliminary crystal structure that shows that only the first two of ten isoprene units of co-enzyme Q10 (CoQ10) interact with the protein. Derivatives with saturated alkyl side chains are very good substrates, indicating that, unlike other ubiquinone oxidoreductases, there is little preference for the methyl branches or rigidity of the CoQ side chain. Few of the compounds that inhibit ubiquinone oxidoreductases inhibit ETF-QO. Compounds found to act as inhibitors of ETF-QO include 2-n-heptyl-4-hydroxyquinoline N-oxide, a naphthoquinone analogue, 2-(3-methylpentyl)-4,6-dinitrophenol and pentachlorophenol. 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), which inhibits the mitochondrial bc1 complex and the chloroplast b6 f complex in redox-dependent fashion, can serve as an electron acceptor for human ETF-QO. The observation of simple Michaelis-Menten kinetic patterns and a single type of quinone-binding site, determined by fluorescence titrations of the protein with DBMIB and 6-(10-bromodecyl)ubiquinone, are consistent with one ubiquinone-binding site per ETF-QO monomer. PMID:14640977

Alternative quinone substrates and inhibitors of human electron-transfer flavoprotein-ubiquinone oxidoreductase.

PubMed

Simkovic, Martin; Frerman, Frank E

2004-03-01

Electron-transfer flavoprotein (ETF)-ubiquinone (2,3-dimethoxy-5-methyl-1,4-benzoquinone) oxidoreductase (ETF-QO) is a membrane-bound iron-sulphur flavoprotein that participates in an electron-transport pathway between eleven mitochondrial flavoprotein dehydrogenases and the ubiquinone pool. ETF is the intermediate electron carrier between the dehydrogenases and ETF-QO. The steady-state kinetic constants of human ETF-QO were determined with ubiquinone homologues and analogues that contained saturated n-alkyl substituents at the 6 position. These experiments show that optimal substrates contain a ten-carbon-atom side chain, consistent with a preliminary crystal structure that shows that only the first two of ten isoprene units of co-enzyme Q10 (CoQ10) interact with the protein. Derivatives with saturated alkyl side chains are very good substrates, indicating that, unlike other ubiquinone oxidoreductases, there is little preference for the methyl branches or rigidity of the CoQ side chain. Few of the compounds that inhibit ubiquinone oxidoreductases inhibit ETF-QO. Compounds found to act as inhibitors of ETF-QO include 2-n-heptyl-4-hydroxyquinoline N-oxide, a naphthoquinone analogue, 2-(3-methylpentyl)-4,6-dinitrophenol and pentachlorophenol. 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), which inhibits the mitochondrial bc1 complex and the chloroplast b6 f complex in redox-dependent fashion, can serve as an electron acceptor for human ETF-QO. The observation of simple Michaelis-Menten kinetic patterns and a single type of quinone-binding site, determined by fluorescence titrations of the protein with DBMIB and 6-(10-bromodecyl)ubiquinone, are consistent with one ubiquinone-binding site per ETF-QO monomer.

Silver baits for the "miraculous draught" of amphiphilic lanthanide helicates.

PubMed

Terazzi, Emmanuel; Guénée, Laure; Varin, Johan; Bocquet, Bernard; Lemonnier, Jean-François; Emery, Daniel; Mareda, Jiri; Piguet, Claude

2011-01-03

The axial connection of flexible thioalkyls chains of variable length (n=1-12) within the segmental bis-tridentate 2-benzimidazole-8-hydroxyquinoline ligands [L12(Cn) -2 H](2-) provides amphiphilic receptors designed for the synthesis of neutral dinuclear lanthanides helicates. However, the stoichiometric mixing of metals and ligands in basic media only yields intricate mixtures of poorly soluble aggregates. The addition of Ag(I) in solution restores classical helicate architectures for n=3, with the quantitative formation of the discrete D(3) -symmetrical [Ln(2) Ag2(L12(C3) -2 H)(3) ](2+) complexes at millimolar concentration (Ln=La, Eu, Lu). The X-ray crystal structure supports the formation of [La(2) Ag(2) (L12(C3) -2 H)(3) ][OTf](2) , which exists in the solid state as infinite linear polymers bridged by S-Ag-S bonds. In contrast, molecular dynamics (MD) simulations in the gas phase and in solution confirm the experimental diffusion measurements, which imply the formation of discrete molecular entities in these media, in which the sulfur atoms of each lipophilic ligand are rapidly exchanged within the Ag(I) coordination sphere. Turned as a predictive tool, MD suggests that this Ag(I) templating effect is efficient only for n=1-3, while for n>3 very loose interactions occur between Ag(I) and the thioalkyl residues. The subsequent experimental demonstration that only 25 % of the total ligand speciation contributes to the formation of [Ln(2) Ag(2) (L12(C12) -2 H)(3) ](2+) in solution puts the bases for a rational approach for the design of amphiphilic helical complexes with predetermined molecular interfaces. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Apoptosis-inducing Factor (AIF) and Its Family Member Protein, AMID, Are Rotenone-sensitive NADH:Ubiquinone Oxidoreductases (NDH-2)*

PubMed Central

Elguindy, Mahmoud M.; Nakamaru-Ogiso, Eiko

2015-01-01

Apoptosis-inducing factor (AIF) and AMID (AIF-homologous mitochondrion-associated inducer of death) are flavoproteins. Although AIF was originally discovered as a caspase-independent cell death effector, bioenergetic roles of AIF, particularly relating to complex I functions, have since emerged. However, the role of AIF in mitochondrial respiration and redox metabolism has remained unknown. Here, we investigated the redox properties of human AIF and AMID by comparing them with yeast Ndi1, a type 2 NADH:ubiquinone oxidoreductase (NDH-2) regarded as alternative complex I. Isolated AIF and AMID containing naturally incorporated FAD displayed no NADH oxidase activities. However, after reconstituting isolated AIF or AMID into bacterial or mitochondrial membranes, N-terminally tagged AIF and AMID displayed substantial NADH:O2 activities and supported NADH-linked proton pumping activities in the host membranes almost as efficiently as Ndi1. NADH:ubiquinone-1 activities in the reconstituted membranes were highly sensitive to 2-n-heptyl-4-hydroxyquinoline-N-oxide (IC50 = ∼1 μm), a quinone-binding inhibitor. Overexpressing N-terminally tagged AIF and AMID enhanced the growth of a double knock-out Escherichia coli strain lacking complex I and NDH-2. In contrast, C-terminally tagged AIF and NADH-binding site mutants of N-terminally tagged AIF and AMID failed to show both NADH:O2 activity and the growth-enhancing effect. The disease mutant AIFΔR201 showed decreased NADH:O2 activity and growth-enhancing effect. Furthermore, we surprisingly found that the redox activities of N-terminally tagged AIF and AMID were sensitive to rotenone, a well known complex I inhibitor. We propose that AIF and AMID are previously unidentified mammalian NDH-2 enzymes, whose bioenergetic function could be supplemental NADH oxidation in cells. PMID:26063804

Effect of Inhibitor Agents Addition on Corrosion Resistance Performance of Titania Sol-Gel Coatings Applied on 304 Stainless Steel

NASA Astrophysics Data System (ADS)

Shanaghi, Ali; Chu, Paul K.; Moradi, Hadi

Hybrid organic-inorganic coatings are deposited on 304 stainless steel substrates by the sol-gel technique to improve the corrosion resistance. A titania-based nanostructured hybrid sol-gel coating is impregnated with three different microencapsulated healing agents (inhibitors) including cerium, Benzotriazole (BTA), and 8-Hydroxyquinoline (8H). Field-emission scanning electron microscopy (FE-SEM) and electrochemical impedance spectroscopy (EIS) are performed to investigate the barrier performance properties. The optimum conditions to achieve corrosion protective coatings for 304 stainless steel were determined. The Nyquist plots demonstrate that the activation time of the coating containing 8H as an organic healing agent shows improved behavior when compared to other coatings including cerium and BTA. Cerium as an inorganic healing agent is second and BTA is third and minimum. An increase in the impedance parameters such as resistance and capacitance as a function of immersion time is achieved in a 3.5wt.% NaCl solution by using healing agents such as BTA. Actually, over the course of immersion, the barrier performance behavior of the coatings changes and reduction of the impedance observed from the coatings containing Ce and 8H discloses deterioration of the protection system after immersion for 96h of immersion in the 3.5% NaCl solution. However, after 96h of immersion time, the concentration of chloride ions is high and causes increase in defects, micro cracks, hole on the surface of hybrid titania nanostructured coating containing Ce and 8H by destruction of coating, and also hybrid titania nanostructured coating containing BTA; BTA is released from coating to improve the resistance of passive film, which is created on the surface.

Up-regulation of hypoxia-inducible factor (HIF)-1α and HIF-target genes in cortical neurons by the novel multifunctional iron chelator anti-Alzheimer drug, M30.

PubMed

Avramovich-Tirosh, Y; Bar-Am, O; Amit, T; Youdim, M B H; Weinreb, O

2010-06-01

Based on a multimodal drug design paradigm, we have synthesized a multifunctional non-toxic, brain permeable iron chelator, M30, possessing the neuroprotective propargylamine moiety of the anti-Parkinsonian drug, rasagiline (Azilect) and antioxidant-iron chelator moiety of an 8-hydroxyquinoline derivative of our iron chelator, VK28. M30 was recently found to confer potential neuroprotective effects in vitro and in various preclinical neurodegenerative models and regulate the levels and processing of the Alzheimer's amyloid precursor protein and its toxic amyloidogenic derivative, Abeta. Here, we show that M30 activates the hypoxia-inducible factor (HIF)-1alpha signaling pathway, thus promoting HIF-1alpha mRNA and protein expression levels, as well as increasing transcription of HIF-1alpha-dependent genes, including vascular endothelial growth factor, erythropoietin, enolase-1, p21 and tyrosine hydroxylase in rat primary cortical cells. In addition, M30 also increased the expression levels of the transcripts of brain derived neurotrophic factor (BDNF) and growth-associated protein-43 (GAP-43). Regarding aspects of relevance to Alzheimer's disease (AD), western blotting analysis of glycogen synthase kinase- 3beta (GSK-3beta) signaling pathway revealed that M30 enhanced the levels of phospho-AKT (Ser473) and phospho- GSK-3beta (Ser9) and attenuated Tau phosphorylation. M30 was also shown to protect cultured cortical neurons against Abeta(25-35) toxicity. All these multimodal pharmacological activities of M30 might be beneficial for its potent efficacy in the prevention and treatment of neurodegenerative conditions, such as Parkinson's disease and AD in which oxidative stress and iron-mediated toxicity are involved.

Copper Capture in a Thioether-Functionalized Porous Polymer Applied to the Detection of Wilson’s Disease

PubMed Central

2016-01-01

Copper is an essential nutrient for life, but at the same time, hyperaccumulation of this redox-active metal in biological fluids and tissues is a hallmark of pathologies such as Wilson’s and Menkes diseases, various neurodegenerative diseases, and toxic environmental exposure. Diseases characterized by copper hyperaccumulation are currently challenging to identify due to costly diagnostic tools that involve extensive technical workup. Motivated to create simple yet highly selective and sensitive diagnostic tools, we have initiated a program to develop new materials that can enable monitoring of copper levels in biological fluid samples without complex and expensive instrumentation. Herein, we report the design, synthesis, and properties of PAF-1-SMe, a robust three-dimensional porous aromatic framework (PAF) densely functionalized with thioether groups for selective capture and concentration of copper from biofluids as well as aqueous samples. PAF-1-SMe exhibits a high selectivity for copper over other biologically relevant metals, with a saturation capacity reaching over 600 mg/g. Moreover, the combination of PAF-1-SMe as a material for capture and concentration of copper from biological samples with 8-hydroxyquinoline as a colorimetric indicator affords a method for identifying aberrant elevations of copper in urine samples from mice with Wilson’s disease and also tracing exogenously added copper in serum. This divide-and-conquer sensing strategy, where functional and robust porous materials serve as molecular recognition elements that can be used to capture and concentrate analytes in conjunction with molecular indicators for signal readouts, establishes a valuable starting point for the use of porous polymeric materials in noninvasive diagnostic applications. PMID:27285482

Biodegradation of 2-methylquinoline by Enterobacter aerogenes TJ-D isolated from activated sludge.

PubMed

Wang, Lin; Li, Yongmei; Duan, Jingyuan

2013-07-01

Bacterial strain Enterobacter aerogenes TJ-D capable of utilizing 2-methylquinoline as the sole carbon and energy source was isolated from acclimated activated sludge under denitrifying conditions. The ability to degrade 2-methylquinoline by E. aerogenes TJ-D was investigated under denitrifying conditions. Under optimal conditions of temperature (35 degrees C) and initial pH 7, 2-methylquinoline of 100 mg/L was degraded within 176 hr. The degradation of 2-methylquinoline by E. aerogenes TJ-D could be well described by the Haldane model (R2 > 0.91). During the degradation period of 2-methylquinoline (initial concentration 100 mg/L), nitrate was almost completely consumed (the removal efficiency was 98.5%), while nitrite remained at low concentration (< 0.62 mg/L) during the whole denitrification period. 1,2,3,4-Tetrahydro-2-methylquinoline, 4-ethyl-benzenamine, N-butyl-benzenamine, N-ethyl-benzenamine and 2,6-diethyl-benzenamine were metabolites produced during the degradation. The degradation pathway of 2-methylquinoline by E. aerogenes TJ-D was proposed. 2-Methylquinoline is initially hydroxylated at C-4 to form 2-methyl-4-hydroxy-quinoline, and then forms 2-methyl-4-quinolinol as a result of tautomerism. Hydrogenation of the heterocyclic ring at positions 2 and 3 produces 2,3-dihydro-2-methyl-4-quinolinol. The carbon-carbon bond at position 2 and 3 in the heterocyclic ring may cleave and form 2-ethyl-N-ethyl-benzenamine. Tautomerism may result in the formation of 2,6-diethyl-benzenamine and N-butyl-benzenamine. 4-Ethyl-benzenamine and N-ethyl-benzenamine were produced as a result of losing one ethyl group from the above molecules.

Hydrogen Metabolism in Helicobacter pylori Plays a Role in Gastric Carcinogenesis through Facilitating CagA Translocation

PubMed Central

Wang, Ge; Romero-Gallo, Judith; Benoit, Stéphane L.; Piazuelo, M. Blanca; Dominguez, Ricardo L.; Morgan, Douglas R.; Peek, Richard M.

2016-01-01

ABSTRACT A known virulence factor of Helicobacter pylori that augments gastric cancer risk is the CagA cytotoxin. A carcinogenic derivative strain, 7.13, that has a greater ability to translocate CagA exhibits much higher hydrogenase activity than its parent noncarcinogenic strain, B128. A Δhyd mutant strain with deletion of hydrogenase genes was ineffective in CagA translocation into human gastric epithelial AGS cells, while no significant attenuation of cell adhesion was observed. The quinone reductase inhibitor 2-n-heptyl-4-hydroxyquinoline-N-oxide (HQNO) was used to specifically inhibit the H2-utilizing respiratory chain of outer membrane-permeabilized bacterial cells; that level of inhibitor also greatly attenuated CagA translocation into AGS cells, indicating the H2-generated transmembrane potential is a contributor to toxin translocation. The Δhyd strain showed a decreased frequency of DNA transformation, suggesting that H. pylori hydrogenase is also involved in energizing the DNA uptake apparatus. In a gerbil model of infection, the ability of the Δhyd strain to induce inflammation was significantly attenuated (at 12 weeks postinoculation), while all of the gerbils infected with the parent strain (7.13) exhibited a high level of inflammation. Gastric cancer developed in 50% of gerbils infected with the wild-type strain 7.13 but in none of the animals infected with the Δhyd strain. By examining the hydrogenase activities from well-defined clinical H. pylori isolates, we observed that strains isolated from cancer patients (n = 6) have a significantly higher hydrogenase (H2/O2) activity than the strains isolated from gastritis patients (n = 6), further supporting an association between H. pylori hydrogenase activity and gastric carcinogenesis in humans. PMID:27531909

Cytochrome b6 arginine 214 of Synechococcus sp. PCC 7002, a key residue for quinone-reductase site function and turnover of the cytochrome bf complex.

PubMed

Nelson, Matthew E; Finazzi, Giovanni; Wang, Qing Jun; Middleton-Zarka, Kelly A; Whitmarsh, John; Kallas, Toivo

2005-03-18

Quinone-reductase (Q(i)) domains of cyanobacterial/chloroplast cytochrome bf and bacterial/mitochondrial bc complexes differ markedly, and the cytochrome bf Q(i) site mechanism remains largely enigmatic. To investigate the bf Q(i) domain, we constructed the mutation R214H, which substitutes histidine for a conserved arginine in the cytochrome b(6) polypeptide of the cyanobacterium Synechococcus sp. SPCC 7002. At high light intensity, the R214H mutant grew approximately 2.5-fold more slowly than the wild type. Slower growth arose from correspondingly slower overall turnover of the bf complex. Specifically, as shown in single flash turnover experiments of cytochrome b(6) reduction and oxidation, the R214H mutation partially blocked electron transfer to the Q(i) site, mimicking the effect of the Q(i) site inhibitor 2-N-4-hydroxyquinoline-N-oxide. The kinetics of cytochrome b(6) oxidation were largely unaffected by hydrogen-deuterium exchange in the mutant but were slowed considerably in the wild type. This suggests that although protonation events influenced the kinetics of cytochrome b(6) oxidation at the Q(i) site in the wild type, electron flow limited this reaction in the R214H mutant. Redox titration of membranes revealed midpoint potentials (E(m,7)) of the two b hemes similar to those in the wild type. Our data define cytochrome b(6) Arg(214) as a key residue for Q(i) site catalysis and turnover of the cytochrome bf complex. In the recent cytochrome bf structures, Arg(214) lies near the Q(i) pocket and the newly discovered c(i) or x heme. We propose a model for Q(i) site function and a role for Arg(214) in plastoquinone binding.

Development of 8-hydroxyquinoline metal based organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Feng, Xiaodong

Because of its potential application for flat panel displays, solid-state lighting and 1.5 mum emitter for fiber optical communications, organic light-emitting diodes (OLEDs) have been intensively researched. One of the major problems with current OLED technology relates to inefficient electron injection at the cathode interface, which causes high driving voltage and poor device stability. Making a low resistance cathode contact for electron injection is critical to device performance. This work mainly focuses on cathode interface design and engineering. The Ohmic contact using a structure of C60/LiF/Al has been developed in electron only devices. It is found that application of the C60/LiF/Al contact to Alq based OLEDs leads to a dramatic reduction in driving voltages, a significant improvement in power efficiency, and a much slower aging process. A new cathode structure based on metal-organic-metal (MOM) tri-layer films has been developed. It is found that MOM cathodes reduce reflection by deconstructive optical interference from two metal films. The absolute reflectance from the MOM tr-ilayer films can be reduced to as low as 7% in the visible light spectrum. In actual working devices, the reflectance can be reduced from ˜80% to ˜20%. MOM cathodes provide a potential low-cost solution for high contrast full-color OLED displays. Low voltage Erq based OLEDs at 1.5 mum emission have been developed. The Erq/Ag cathode interface has been found to be efficient for electron injection. Dramatic improvement in driving voltage and power efficiency has been realized by implementing Bphen and C60 into Erq devices as an electron transport layer. Integration of Erq devices on Si wafers has also been demonstrated.

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.

Hyperfine interaction and its effects on spin dynamics in organic solids

NASA Astrophysics Data System (ADS)

Yu, Z. G.; Ding, Feizhi; Wang, Haobin

2013-05-01

Hyperfine interaction (HFI) and spin-orbit coupling are two major sources that affect electron spin dynamics. Here we present a systematic study of the HFI and its role in organic spintronic applications. For electron spin dynamics in disordered π-conjugated organics, the HFI can be characterized by an effective magnetic field whose modular square is a weighted sum of contact and dipolar contributions. We determine the effective HFI fields of some common π-conjugated organics studied in the literature via first-principles calculations. Most of them are found to be less than 2 mT. While the H atoms are the major source of the HFI in organics containing only the C and H atoms, many organics contain other nuclear spins, such as Al and N in tris-(8-hydroxyquinoline) aluminum, that contribute to the total HFI. Consequently, the deuteration effect on the HFI in the latter may be much weaker than in the former. The HFI gives rise to multiple resonance peaks in electron spin resonance. In disordered organic solids, these individual resonances are unresolved, leading to a broad peak whose width is proportional to the effective HFI field. As electrons hop among adjacent organic molecules, they experience a randomly varying local HFI field, inducing electron spin relaxation and diffusion. This is analyzed rigorously based on master equations. Electron spin relaxation undergoes a crossover along the ratio between the electron hopping rate η¯ and the Larmor frequency Ω of the HFI field. The spin relaxation rate increases (decreases) with η¯ when η¯≪Ω (η¯≫Ω). A coherent beating of electron spin at Ω is possible when the external field is small compared to the HFI. In this regime, the magnetic field is found to enhance the spin relaxation.

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).

Angiotensin I-converting enzyme inhibitors potentiate bradykinin's inotropic effects independently of blocking its inactivation.

PubMed

Minshall, R D; Erdös, E G; Vogel, S M

1997-08-04

The positive inotropic effects of bradykinin (BK) and 2 analogs resistant to angiotensin I-converting enzyme (ACE) were potentiated on isolated guinea pig atrial preparations by enalaprilat. The stable BK analogs, dextran-BK and [Hyp3-Tyr(Me)8]-BK, were as active as BK. Pretreatment for 5 min with enalaprilat augmented the maximal positive inotropic effect of [Hyp3-Tyr(Me)8]-BK 2.8-fold, from 19% to 53% and that of BK from 28% to 42% over baseline; inotropic responses to dextran-BK (1 microM) were similarly increased. The activity of atrial ACE, a zinc-requiring enzyme, was completely inhibited by 8-hydroxyquinoline-5-sulfonic acid (QSA, 10 mM), which raised the maximal inotropic effect of BK to 39% above baseline. This value rose to 67% when in addition to QSA, 1 microM enalaprilat was added; enalaprilat thus, potentiated the effects of BK independently of enzyme inhibition. The positive inotropic effects to BK and its analogs decline with time in the presence of these agonists. After 10 min of exposure, the response to 1 microM [Hyp3-Tyr(Me)8]-BK decreased to about half, and after 20 min, to 0. Enalaprilat, when present in the tissue bath, prevented the decline in inotropy; even after tachyphylaxis occurred, it reversed this decrease in activity when added. The effects of 1 microM [Hyp3-Tyr(Me)8]-BK, in the absence or presence of enalaprilat, were abolished by the BK B2 receptor antagonist icatibant (0.75 microM). The results indicate that ACE inhibitors, by potentiating the BK effects and blocking BK B2-receptor desensitization, may contribute to the beneficial cardiac effects of BK independently of blocking its inactivation.

X-rays sensing properties of MEH-PPV, Alq₃ and additive components: a new organic dosimeter as a candidate for minimizing the risk of accidents of patients undergoing radiation oncology.

PubMed

Schimitberger, T; Ferreira, G R; Akcelrud, L C; Saraiva, M F; Bianchi, R F

2013-01-01

In this paper, we report our experimental design in searching a smart and easy-to-read dosimeter used to detect 6 MV X-rays for improving patient safety in radiation oncology. The device was based on an organic emissive solutions of poly(2-methoxy-5(2'-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV), aluminum-tris-(8-hydroxyquinoline) (Alq₃) and additive components which were characterized by UV-Vis absorption, photoluminescence and CIE color coordinate diagram. The optical properties of MEH-PPV/Alq₃ solutions have been examined as function of radiation dose over the range of 0-100 Gy. It has shown that MEH-PPV/Alq₃ solutions are specifically sensitive to X-rays, since the effect of radiation on this organic system is strongly correlated with the efficient spectral overlap between Alq₃ emission and the absorption of degraded MEH-PPV, which alters the color and photoemission of MEH-PPV/Alq₃ mixtures from red to yellow, and then to green. The rate of this change is more sensitive when MEH-PPV/Alq₃ is irradiated in the presence of benzoyl peroxide than when in the presence of hindered phenolic stabilizers, respectively, an accelerator and an inhibitor to activate or inhibit free radical formation. This gives rise to optimize the response curve of the dosimeter. It is clear from the experimental results that organic emissive semiconductors have potential to be used as dedicated and low-cost dosimeters to provide an independent check of beam output of a linear accelerator and therefore to give patients the opportunity to have information on the dose prescription or equipment-related problems a few minutes before being exposed to radiation. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

Thermo-Responsive Amphiphilic Block Copolymers Stablilized Gold Nanoparticles: Synthesis and High Catalytic Properties.

PubMed

Lü, Jianhua; Yang, Yu; Gao, Junfang; Duan, Haichao; Lü, Changli

2018-06-19

A series of novel well-defined 8-hydroxyquinoline (HQ)-containing thermo-responsive amphiphilic diblock copolymers poly(styrene-co-5-(2-methacryloylethyloxy- methyl)-8-quinolinol)-b-poly(N-isopropylacrylamide) P(St-co-MQ)-b-PNIPAm (P1,2), P(NIPAm- co-MQ)-b-PSt (P3,4) and triblock copolymer poly(N-isopropylacrylamide)-b-poly(methyl- methacrylate-co-5-(2-methacryloylethyloxymethyl)-8-quinolinol)-b-polystyrene PNIPAm-b- P(MMA-co-MQ)-b-PSt (P5) were prepared by reversible addition fragmentation chain transfer (RAFT) polymerization, and their self-assembly behaviors were studied. The block copolymers P1-P5 stabilized gold nanoparticles (Au@P1-Au@P5) with small size and narrow distribution were obtained through in situ reduction of gold precursors in aqueous solution of polymer micelles with HQ as the coordination groups. The resulting Au@P nanohybrids possessed excellent catalytic activities for the reduction of nitrophenols using NaBH4. The size, morphology and surface chemistry of Au NPs could be controlled by adjusting the structure of block polymers with HQ in different block positions, which plays an important role in the catalytic properties. It was found that longer chain length of hydrophilic or hydrophobic segments of block copolymers were beneficial to elevate the catalytic activity of Au NPs for the reduction of nitrophenols, and the spherical nanoparticles (Au@P5) stabilized with triblock copolymer exhibit higher catalytic performance. Surprisingly, the gold nanowires (Au@P4) produced with P4 have a highest catalytic activity due to large abundance of grain boundaries. Excellent thermo-responsive behaviors for catalytic reaction make the as-prepared Au@P hybrids become an environmentally responsive nano-catalytic materials.

Simultaneous determination of suspended particulate trace metals (Co, Ni, Cu, Zn, Cd and Pb) in seawater with small volume filtration assisted by microwave digestion and flow injection inductively coupled plasma mass spectrometer.

PubMed

Nakatsuka, Seiji; Okamura, Kei; Norisuye, Kazuhiro; Sohrin, Yoshiki

2007-06-26

A new technique for the determination of suspended particulate trace metals (P-metals >0.2 microm), such as Co, Ni, Cu, Zn, Cd and Pb, in open ocean seawater has been developed by using microwave digestion coupled with flow injection inductively coupled plasma mass spectrometry (FI-ICP-MS). Suspended particulate matter (SPM) was collected from 500 mL of seawater on a Nuclepore filter (0.2 microm) using a closed filtration system. Both the SPM and filter were completely dissolved by microwave digestion. Reagents for the digestion were evaporated using a clean evaporation system, and the metals were redissolved in 0.8 M HNO3. The solution was diluted with buffer solution to give pH 5.0 and the metals were determined by FI-ICP-MS using a chelating adsorbent of 8-hydroxyquinoline immobilized on fluorinated metal alkoxide glass (MAF-8HQ). The procedure blanks with a filter were found to be 0.048+/-0.008, 10.3+/-0.3, 0.27+/-0.05, 3.3+/-1.8, 0.02+/-0.03 and 0.85+/-0.09 ng L(-1) for Co, Ni, Cu, Zn, Cd and Pb, respectively (n=14). Detection limits defined as 3 times the standard deviation of the blanks were 0.023, 0.90, 0.14, 5.3, 0.078 and 0.28 ng L(-1) for Co, Ni, Cu, Zn, Cd and Pb, respectively. Accuracy was evaluated using certified reference materials of chlorella (NES CRM No. 3) and marine sediment (HISS-1). The method was applied to the determination of vertical distributions for P-Co, Ni, Cu, Zn, Cd and Pb in the Western North Pacific.

Systematic approach in Mg2+ ions analysis with a combination of tailored fluorophore design.

PubMed

Lvova, L; Guanais Gonçalves, C; Prodi, L; Sgarzi, M; Zaccheroni, N; Lombardo, M; Legin, A; Di Natale, C; Paolesse, R

2017-10-02

A systematic study of a series of diaza-18-crown-6 8-hydroxyquinoline (DCHQ) chemosensors, devoted to Mg(II) ion detection, was performed. Functionalization of DCHQ by peripheral substituents allowed the development of novel all-solid-state optodes via inclusion inside PVC-based polymeric films. The influence on the DCHQ-based optode response of the lipophilic sites functionalization and of the nature of the plasticizer, was investigated. Fluorimetric studies on optodes sensitivity towards a number of different metal cations (Ca 2+ , Na + , K + , Li + , Co 2+ , Cd 2+ , Pb 2+ , Cu 2+ , Hg 2+ , Zn 2+ ) and NH 4 + were carried out. The results demonstrated the suitability of the DCHQ optodes to perform fast monitoring (<10s) of magnesium (II) ions. Emission light signal was sufficiently brilliant to be captured by a low-cost computer webcam. The phenyl-substituted DCHQ-Ph derivative showed the best performance with a wide range for Mg(II) ion determination between 2.7 × 10 -7 and 2.2 × 10 -2  mol/L. It was possible, therefore, to determine the concentrations of Mg(II) in commercial fertilizer samples by DCHQ-Ph-based optodes with acceptable results: recoveries of 96.2-104.9% and relative standard deviation (RSD, n = 6) less than 5%. Moreover, in comparison to single sensors, the use of an array composed of five optodes (the ones showing the best performances in the preliminary tests) has allowed to reduce the RSD of magnesium determination in real samples (down to 3.7% with respect to 5.5% for single optodes) and to achieve a detection limit (estimated by s/n = 3 method) as low as 4.6 × 10 -7  mol/L. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Isolation and reconstitution of iron- and manganese-containing superoxide dismutases from Bacteroides thetaiotaomicron.

PubMed Central

Pennington, C D; Gregory, E M

1986-01-01

Superoxide dismutase (SOD) from extracts of anaerobically maintained Bacteroides thetaiotaomicron was a dimer of equally sized 23,000-molecular-weight monomers joined noncovalently. A preparation with a specific activity of 1,200 U/mg contained 1.1 g-atom of Fe, 0.6 g-atom of Zn, and less than 0.05 g-atom of Mn per mol of dimer. The apoprotein, prepared by dialysis of iron-SOD in 5 M guanidinium chloride-20 mM 8-hydroxyquinoline, had no superoxide-scavenging activity when renatured without exogenous metal. Enzymatic activity was restored to the denatured apoprotein by dialysis against either 1 mM Fe(NH4)2 or 1 mM MnCl2 in 20 mM Tris (pH 7.0). The Fe-reconstituted enzyme and the native enzyme were inhibited approximately 50% by 0.2 mM NaN3, whereas the Mn-reconstituted enzyme was inhibited 60% by 10 mM NaN3. Aeration of the anaerobic cells resulted in a fourfold induction of an azide-resistant SOD. The enzyme (43,000 molecular weight) isolated from aerated cells was a dimer of equally sized subunits. The metal content was 1.0 g-atom of Mn, 0.55 g-atom of Fe, and 0.3 g-atom of Zn per mol of dimer. Enzymatic activity of the denatured apoprotein from this enzyme was also restored on addition of either iron or manganese. The constitutive Fe-SOD and the O2-induced Mn-SOD, tested alone and in combination, migrated identically on acrylamide gels, had similar amino acid compositions, and had alanine as the sole N-terminal amino acid. These data are consistent with the synthesis of a single apoprotein in either anaerobically maintained or oxygenated cells. We have observed a similar phenomenon with SOD from Bacteroides fragilis (E. M. Gregory, Arch. Biochem. Biophys. 238:83-89, 1985). PMID:3700336

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.

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.

Efficient blue and white polymer light emitting diodes based on a well charge balanced, core modified polyfluorene derivative.

PubMed

Das, Dipjyoti; Gopikrishna, Peddaboodi; Singh, Ashish; Dey, Anamika; Iyer, Parameswar Krishnan

2016-03-14

Fabrication of efficient blue and white polymer light-emitting diodes (PLEDs) using a well charge balanced, core modified polyfluorene derivative, poly[2,7-(9,9'-dioctylfluorene)-co-N-phenyl-1,8-naphthalimide (99:01)] (PFONPN01), is presented. The excellent film forming properties as observed from the morphological study and the enhanced electron transport properties due to the inclusion of the NPN unit in the PFO main chain resulted in improved device properties. Bright blue light was observed from single layer PLEDs with PFONPN01 as an emissive layer (EML) as well as from double layer PLEDs using tris-(8-hydroxyquinoline) aluminum (Alq3) as an electron transporting layer (ETL) and LiF/Al as a cathode. The effect of ETL thickness on the device performance was studied by varying the Alq3 thickness (5 nm, 10 nm and 20 nm) and the device with an ETL thickness of 20 nm was found to exhibit the maximum brightness value of 11 662 cd m(-2) with a maximum luminous efficiency of 4.87 cd A(-1). Further, by using this highly electroluminescent blue PFONPN01 as a host and a narrow band gap, yellow emitting small molecule, dithiophene benzothiadiazole (DBT), as a guest at three different concentrations (0.2%, 0.4% and 0.6%), WPLEDs with the ITO/PEDOT:PSS/emissive layer/Alq3(20 nm)/LiF/Al configuration were fabricated and maximum brightness values of 8025 cd m(-2), 9565 cd m(-2) and 10 180 cd m(-2) were achieved respectively. 0.4% DBT in PFONPN01 was found to give white light with Commission International de l'Echairage (CIE) coordinates of (0.31, 0.38), a maximum luminous efficiency of 6.54 cd A(-1) and a color-rendering index (CRI) value of 70.

Enhanced PL and EL properties of Alq3/nano-TiO2 with the modification of 8-vinyl POSS

NASA Astrophysics Data System (ADS)

Li, Jie; Xie, Bing; Xia, Kai; Zhao, Chunmao; Li, Yingchun; Hu, Shengliang

2018-04-01

In this study, tris (8-hydroxyquinoline) aluminum/nano-titanium dioxide (Alq3/nano-TiO2) composites were synthesized using a simply in-situ process with 8-vinyl polyhedral oligomeric silsesquioxane (POSS) as a modifier. The as-prepared Alq3/nano-TiO2 composites were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet visible (UV-vis) absorption spectra. The effect of modification on luminescence properties for the samples was studied by photoluminescence (PL) spectra, electroluminescence (EL) spectra and time-resolved luminescence decay curves. Organic light emitting diodes (OLEDs) with the corresponded emitting layer structure were investigated. The results show that the amphiphilicity of the 8-vinyl POSS leads to well-dispersion state of the nano-TiO2 in the Alq3. Adding a proper weight percentage of 8-vinyl POSS is beneficial for the PL and EL properties enhancement of the composites. OLED using the Alq3/nano-TiO2 with 1 wt% 8-vinyl POSS emitting layer has the low turn-on voltage (4.7 V at 1 cd/m2), high maximum luminance (7463 cd/m2 at 8.75 V), and high luminous efficiency (1.13 cd/A at 100 mA/cm2). Adding 1 wt% 8-vinyl POSS in Alq3/nano-TiO2 can increase the EL intensity by a factor of 37.1 at 8 V. These values are better than those for OLEDs using the Alq3 emitting layer. The increase in luminance and current efficiency stability can be attributed to the energy transfer process between the Alq3 and the nano-TiO2, and the suppression of the self-quenching by caged 8-vinyl POSS molecules.

Apoptosis-inducing Factor (AIF) and Its Family Member Protein, AMID, Are Rotenone-sensitive NADH:Ubiquinone Oxidoreductases (NDH-2).

PubMed

Elguindy, Mahmoud M; Nakamaru-Ogiso, Eiko

2015-08-21

Apoptosis-inducing factor (AIF) and AMID (AIF-homologous mitochondrion-associated inducer of death) are flavoproteins. Although AIF was originally discovered as a caspase-independent cell death effector, bioenergetic roles of AIF, particularly relating to complex I functions, have since emerged. However, the role of AIF in mitochondrial respiration and redox metabolism has remained unknown. Here, we investigated the redox properties of human AIF and AMID by comparing them with yeast Ndi1, a type 2 NADH:ubiquinone oxidoreductase (NDH-2) regarded as alternative complex I. Isolated AIF and AMID containing naturally incorporated FAD displayed no NADH oxidase activities. However, after reconstituting isolated AIF or AMID into bacterial or mitochondrial membranes, N-terminally tagged AIF and AMID displayed substantial NADH:O₂ activities and supported NADH-linked proton pumping activities in the host membranes almost as efficiently as Ndi1. NADH:ubiquinone-1 activities in the reconstituted membranes were highly sensitive to 2-n-heptyl-4-hydroxyquinoline-N-oxide (IC₅₀ = ∼1 μm), a quinone-binding inhibitor. Overexpressing N-terminally tagged AIF and AMID enhanced the growth of a double knock-out Escherichia coli strain lacking complex I and NDH-2. In contrast, C-terminally tagged AIF and NADH-binding site mutants of N-terminally tagged AIF and AMID failed to show both NADH:O₂ activity and the growth-enhancing effect. The disease mutant AIFΔR201 showed decreased NADH:O₂ activity and growth-enhancing effect. Furthermore, we surprisingly found that the redox activities of N-terminally tagged AIF and AMID were sensitive to rotenone, a well known complex I inhibitor. We propose that AIF and AMID are previously unidentified mammalian NDH-2 enzymes, whose bioenergetic function could be supplemental NADH oxidation in cells. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

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%. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of changes in membrane sodium flux on virulence gene expression in Vibrio cholerae

PubMed Central

Häse, Claudia C.; Mekalanos, John J.

1999-01-01

The expression of several virulence factors of Vibrio cholerae is coordinately regulated by the ToxT molecule and the membrane proteins TcpP/H and ToxR/S, which are required for toxT transcription. To identify proteins that negatively affect toxT transcription, we screened transposon mutants of V. cholerae carrying a chromosomally integrated toxT∷lacZ reporter construct for darker blue colonies on media containing 5-bromo-4-chlor-3-indolyl β-d galactoside (X-gal). Two mutants had transposon insertions in a region homologous to the nqr gene cluster of Vibrio alginolyticus, encoding a sodium-translocating NADH–ubiquinone oxidoreductase (NQR). In V. alginolyticus, NQR is a respiration-linked Na+ extrusion pump generating a sodium motive force that can be used for solute import, ATP synthesis, and flagella rotation. Inhibition of NQR enzyme function in V. cholerae by the specific inhibitor 2-n-heptyl-4-hydroxyquinoline N-oxide (HQNO) resulted in elevated toxT∷lacZ activity. Increased toxT∷lacZ expression in an nqr mutant strain compared with the parental strain was observed when the TcpP/H molecules alone were strongly expressed, suggesting that the negative effect of the NQR complex on toxT transcription is mediated through TcpP/H. However, the ability of the TcpP/H proteins to activate the toxT∷lacZ reporter construct was greatly diminished in the presence of high NaCl concentrations in the growth medium. The flagellar motor of V. cholerae appears to be driven by a sodium motive force, and modulation of flagella rotation by inhibitory drugs, high media viscosity, or specific mutations resulted in increases of toxT∷lacZ expression. Thus, the regulation of the main virulence factors of V. cholerae appears to be modulated by endogenous and exogenous sodium levels in a complex way. PMID:10077658

Charge transfer and injection barrier at the metal-organic interfaces

NASA Astrophysics Data System (ADS)

Yan, Li

2002-09-01

The metal-organic interface plays a critical role in determining the functionality and performance of many innovative organic based devices. It has attracted extensive research interests in recent years. This thesis presents investigations of the electronic structures of organic materials, such as tris-(8-hydroxyquinoline) aluminum (Alq3) and copper phthalocyanine (CuPc), during their interface formation with metals. The characterization is accomplished by X-ray and ultraviolet photoelectron spectroscopes (XPS and UPS) and inverse photoelectron spectroscopy (IPES). As discussed herein, both occupied and unoccupied electronic states at the interfaces are carefully examined in different aspects. In Chapter 4, the charge transfer and chemical reaction at various metal/Alq3 interfaces are investigated using XPS and UPS to study the electron injection into the Alga film. Electron transfer from the low work function metal and Al/LiF(CsF) bilayer to the Alga has been observed. The role of the dielectric and possible chemistry at the interface are discussed in comparison of the low work function metals. Further in Chapter 5, the origin of the metal-interface dipole and the estimation of charge injection barrier is explored using several organic materials. A thermodynamic equilibrium model is extended to explain the relation between the charge transfer process ad the interface dipole. Further, in Chapter 6 the combination of XPS, UPS and IPES detailed the evolution of both occupied and unoccupied energy states during the alkali metal doping. The energy gap modification in organic due to metal doping is observed directly for the spectra. Chapter 7 provides stability study of the organic thin films under x-ray and UV light. The results verify the usability of UPS and XPS for the organic materials used in the thesis. Chapter 7 also shows the secondary ion mass spectroscopy results of metal diffusion in organic thin films.

Analysis of monoamine oxidase (MAO) enzymatic activity by high-performance liquid chromatography-diode array detection combined with an assay of oxidation with a peroxidase and its application to MAO inhibitors from foods and plants.

PubMed

Herraiz, Tomás; Flores, Andrea; Fernández, Lidia

2018-01-15

Monoamine oxidase (MAO) enzymes catalyze the oxidative deamination of biogenic amines and neurotransmitters and produce ammonia, aldehydes, and hydrogen peroxide which is involved in oxidative processes. Inhibitors of MAO-A and -B isozymes are useful as antidepressants and neuroprotectants. The assays of MAO usually measure amine oxidation products or hydrogen peroxide by spectrophotometric techniques. Those assays are often compromised by interfering compounds resulting in poor results. This research describes a new method that combines in the same assay the oxidative deamination of kynuramine to 4-hydroxyquinoline analyzed by HPLC-DAD with the oxidation of tetramethylbenzidine (TMB) (or Amplex Rex) by horseradish peroxidase (HRP) in presence of hydrogen peroxide. The new method was applied to study the inhibition of human MAO-A and -B by bioactive compounds including β-carboline alkaloids and flavonoids occurring in foods and plants. As determined by HPLC-DAD, β-carbolines, methylene blue, kaempferol and clorgyline inhibited MAO-A and methylene blue, 5-nitroindazole, norharman and deprenyl inhibited MAO-B, and all of them inhibited the oxidation of TMB in the same extent. The flavonoids catechin and cyanidin were not inhibitors of MAO by HPLC-DAD but highly inhibited the oxidation of TMB (or Amplex Red) by peroxidase whereas quercetin and resveratrol were moderate inhibitors of MAO-A by HPLC-DAD, but inhibited the peroxidase assay in a higher level. For some phenolic compounds, using the peroxidase-coupled assay to measure MAO activity led to mistaken results. The new method permits to discern between true inhibitors of MAO from those that are antioxidants and which interfere with peroxidase assays but do not inhibit MAO. For true inhibitors of MAO, inhibition as determined by HPLC-DAD correlated well with inhibition of the oxidation of TMB and this approach can be used to assess the in vitro antioxidant activity (less hydrogen peroxide production) resulting from MAO inhibition. Copyright © 2017 Elsevier B.V. All rights reserved.

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 one of the major losses that limit the power conversion efficiency of OPV devices is the formation of triplet excitons in the polymer through recombination of charge-transfer (CT) excitons at the interface, and presented a method to suppress the dissociation of CT states by incorporating the spin ½ additive, galvinoxyl in the bulk heterojunction architecture of the active organic blend layer.

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 used to probe the electronic structure of individual atomic sites within a molecule. Most of the results in this thesis are accompanied by the results of electronic structure calculations determined with density functional theory (DFT). DFT is a useful aid in interpreting the results of the x-ray spectroscopies employed. The experimental results, combined with DFT calculations, provide a wealth of information regarding the electronic structures of these organic materials. v

Characterization of 1-Aminobenzotriazole and Ketoconazole as Novel Inhibitors of Monoamine Oxidase (MAO): An In Vitro Investigation.

PubMed

Shaik, Abdul Naveed; LeDuc, Barbara W; Khan, Ansar A

2017-10-01

1-Aminobenzotriazole, a known time-dependent inhibitor of cytochrome P450 (CYP) enzymes, and ketoconazole, a strong inhibitor of the human CYP3A4 isozyme, are used as standard probe inhibitors to characterize the CYP and/or non-CYP-mediated metabolism of xenobiotics. In the present investigation, 1-Aminobenzotriazole and ketoconazole are characterized as potent monoamine oxidase (MAO) inhibitors in vitro using mouse, rat and human liver microsomes and S9 fractions. Inhibition potential of 1-aminobenzotriazole and ketoconazole was studied in mice, rat and human liver microsomes, S9 fractions, MAO-A and MAO-B expressed enzymes by monitoring the formation of 4-hydroxyquinoline (4-HQ) from kynuramine, a specific substrate of MAO by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Mechanism of MAO inhibition was studied by incubating varying concentration of kynuramine with mouse, rat and human S9 fractions at varying concentration of 1-aminobenzatriazole and ketoconazole and monitoring the formation of 4-HQ. 1-aminobenzotriazole and ketoconazole inhibited both MAO isozymes (MAO-A and MAO-B) with more specificity towards MAO-B. Kynuramine substrate kinetics in mouse, rat and human S9 fractions with varying 1-aminobenzotriazole and ketoconazole concentrations showed decreased maximum rate (V max ) for 4-HQ formation without affecting the Michaelis-Menten constant (K m ). A non-competitive inhibition model was constructed and inhibition constants (K i ) for 1-aminobenzotriazole (7.87 ± 0.61, 8.61 ± 0.92, 65.2 ± 1.61 µM for mice, rat and humans, respectively) and ketoconazole (0.12 ± 0.01, 2.04 ± 0.08, 5.52 ± 0.47 µM for mice, rat and humans, respectively) were determined. 1-Aminobenzotriazole and ketoconazole are characterized as non-competitive inhibitors of mice, rat and human MAO in vitro and the extent of their MAO inhibition potential is species specific. 1-Aminobenzotriazole or ketoconazole can be used as a probe inhibitor in vitro for screening the involvement of MAO-dependent metabolism of new chemical entities (NCE) in early drug discovery.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morita, Akinori, E-mail: morita@tokushima-u.ac.jp; Ariyasu, Shinya; Wang, Bing

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 micemore » 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.« less

On line automated system for the determination of Sb(V), Sb(III), thrimethyl antimony(v) and total antimony in soil employing multisyringe flow injection analysis coupled to HG-AFS.

PubMed

Silva Junior, Mario M; Portugal, Lindomar A; Serra, Antonio M; Ferrer, Laura; Cerdà, Victor; Ferreira, Sergio L C

2017-04-01

This paper proposes the use of a multisyringe flow injection analysis (MSFIA) system for inorganic antimony speciation analysis, trimethyl antimony(V) and determination of total antimony in soil samples using hydride generation atomic fluorescence spectrometry (HG-AFS). Total antimony has been determined after reduction of antimony(V) to antimony(III) using potassium iodide and ascorbic acid. For determination of total inorganic antimony the sample is percolated in a mini-column containing the Dowex 50W-X8 resin for retention of the organic species of antimony. Antimony(III) is quantified in presence of 8-hydroxyquinoline as masking agent for antimony(V) after an extraction step of the organic antimony species using the also same mini-column. The trimethyl antimony(V) content is found by difference between total antimony and total inorganic antimony. By other hand, antimony(V) is quantified by difference between total inorganic antimony and antimony(III). The analytical determinations were performed using sodium tetrahydroborate as reducing agent. The optimization step was performed using two-level full factorial design and Doehlert matrix involving the factors: hydrochloric acid and sodium tetrahydroborate concentrations and sample flow rate. The optimized experimental conditions allow the antimony determination utilizing the external calibration technique with limits of detection and quantification of 0.9 and 3.1ngg -1 , respectively, and a precision expressed as relative standard deviation of 3.2% for an antimony solution of 5.0µgL -1 . The method accuracy was confirmed by analysis of the soil certified reference material furnished from Sigma-Aldrich RTC. Additionally, addition/recovery tests were performed employing synthetic solutions prepared using trimethyl antimony(V), antimony(III), antimony(V) and five soil samples. The antimony extraction step was performed in a closed system using hydrochloric acid, ultrasonic radiation and controlled temperature. The method proposed was applied for analysis of thirteen soil samples collected in different sites of the Balearic Islands, Spain, and the results obtained varied from 19 to 46ngg -1 for trimethyl antimony(V) and from 113 to 215ngg -1 for total inorganic antimony. The concentrations obtained to antimony(V) were always higher than for antimony(III) in all the analyzed samples. Copyright © 2017 Elsevier B.V. All rights reserved.

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. Implicit throughout our study, we assume that regions of high electric field will likely induce chemical changes and hence breakdown in the OLED. Our electrical measurements suggest that at least 6% of the applied potential may be concentrated at the interfaces. Spectroscopic measurements suggest that chemical reaction does occur there (namely the electrode/Alq3 interface), thus leading to device failure and suggest a course of action to avoid this fate with other OLED systems.

Ultrahigh density array of vertically aligned small-molecular organic nanowires on arbitrary substrates.

PubMed

Starko-Bowes, Ryan; Pramanik, Sandipan

2013-06-18

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 and spintronics. Recently we have been able to address the above-mentioned issue by employing a novel "centrifugation-assisted" approach. This method therefore broadens the spectrum of organic materials that can be patterned in a vertically ordered nanowire array. Due to the technological importance of Alq3, rubrene and methanofullerenes, our method can be used to explore how the nanostructuring of these materials affects the performance of aforementioned organic devices. The purpose of this article is to describe the technical details of the above-mentioned protocol, demonstrate how this process can be extended to grow small-molecular organic nanowires on arbitrary substrates and finally, to discuss the critical steps, limitations, possible modifications, trouble-shooting and future applications.

Targeting Innate Immunity for Antiviral Therapy through Small Molecule Agonists of the RLR Pathway

PubMed Central

Pattabhi, Sowmya; Wilkins, Courtney R.; Dong, Ran; Knoll, Megan L.; Posakony, Jeffrey; Kaiser, Shari; Mire, Chad E.; Wang, Myra L.; Ireton, Renee C.; Geisbert, Thomas W.; Bedard, Kristin M.; Iadonato, Shawn P.

2015-01-01

ABSTRACT The cellular response to virus infection is initiated when pathogen recognition receptors (PRR) engage viral pathogen-associated molecular patterns (PAMPs). This process results in induction of downstream signaling pathways that activate the transcription factor interferon regulatory factor 3 (IRF3). IRF3 plays a critical role in antiviral immunity to drive the expression of innate immune response genes, including those encoding antiviral factors, type 1 interferon, and immune modulatory cytokines, that act in concert to restrict virus replication. Thus, small molecule agonists that can promote IRF3 activation and induce innate immune gene expression could serve as antivirals to induce tissue-wide innate immunity for effective control of virus infection. We identified small molecule compounds that activate IRF3 to differentially induce discrete subsets of antiviral genes. We tested a lead compound and derivatives for the ability to suppress infections caused by a broad range of RNA viruses. Compound administration significantly decreased the viral RNA load in cultured cells that were infected with viruses of the family Flaviviridae, including West Nile virus, dengue virus, and hepatitis C virus, as well as viruses of the families Filoviridae (Ebola virus), Orthomyxoviridae (influenza A virus), Arenaviridae (Lassa virus), and Paramyxoviridae (respiratory syncytial virus, Nipah virus) to suppress infectious virus production. Knockdown studies mapped this response to the RIG-I-like receptor pathway. This work identifies a novel class of host-directed immune modulatory molecules that activate IRF3 to promote host antiviral responses to broadly suppress infections caused by RNA viruses of distinct genera. IMPORTANCE Incidences of emerging and reemerging RNA viruses highlight a desperate need for broad-spectrum antiviral agents that can effectively control infections caused by viruses of distinct genera. We identified small molecule compounds that can selectively activate IRF3 for the purpose of identifying drug-like molecules that can be developed for the treatment of viral infections. Here, we report the discovery of a hydroxyquinoline family of small molecules that can activate IRF3 to promote cellular antiviral responses. These molecules can prophylactically or therapeutically control infection in cell culture by pathogenic RNA viruses, including West Nile virus, dengue virus, hepatitis C virus, influenza A virus, respiratory syncytial virus, Nipah virus, Lassa virus, and Ebola virus. Our study thus identifies a class of small molecules with a novel mechanism to enhance host immune responses for antiviral activity against a variety of RNA viruses that pose a significant health care burden and/or that are known to cause infections with high case fatality rates. PMID:26676770

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 and spintronics. Recently we have been able to address the above-mentioned issue by employing a novel "centrifugation-assisted" approach. This method therefore broadens the spectrum of organic materials that can be patterned in a vertically ordered nanowire array. Due to the technological importance of Alq3, rubrene and methanofullerenes, our method can be used to explore how the nanostructuring of these materials affects the performance of aforementioned organic devices. The purpose of this article is to describe the technical details of the above-mentioned protocol, demonstrate how this process can be extended to grow small-molecular organic nanowires on arbitrary substrates and finally, to discuss the critical steps, limitations, possible modifications, trouble-shooting and future applications. PMID:23852129

Synthesis, characterization, and application of novel Zn(II)-ionic imprinted polymer for preconcentration of Zn(II) ions from aqueous solution

NASA Astrophysics Data System (ADS)

Wirawan, T.; Supriyanto, G.; Soegianto, A.

2018-04-01

Preparation of a new Zn2+ ion-imprinted polymer (Zn-IIP) is presented in this report. The Zn-IIP are prepared by precipitation polymerization using 8-hydroxyquinoline (8HQ) as a ligand, methacrylic acid (MAA) as functional monomer, and ethylene glycol dimethacrylate (EGDMA) as a cross-linker has been prepared. The benzoyl peroxide and ethanol/acetonitrile (2:1) mixture were used as initiator and porogen, respectively. Precipitation polymerization was carried out by heating in a water bath at 60°C for 8 hours. After polymerization, cavities in the polymer particles corresponding to the Zn2+ ions were created by leaching the polymer with 2 mol L-1 HNO3. The polymer was washed with aquabidest and dried in an oven at the temperature of 60°C for 24 hours. The Zn-IIP was characterized by Fourier Transform Infrared Spectrophotometry (FT-IR) and Scanning Electron Microscopy (SEM). The synthesized Zn-IIP was used as a new adsorbent for solid phase extraction (SPE) of Zn(II) prior to Flame Atomic Absorption Spectrometry (FAAS) determination. The experimental parameters for SPE, such as pH of the sample, loading rate, and elution volume, have been optimized. The effect of pH of the sample on the extraction of analyte was studied in batch mode. The effects of loading rate and elution volume on the extraction of analyte were studied in dynamic mode by loading of the sample through IIP-SPE cartridge containing 100 mg of the synthesized Zn-IIP. The imprinted polymer (Zn-IIP) have bands at 3433.06 cm-1 (O-H), 1508.23 cm-1 (C=N aromatics), 1284.5 cm-1 (C-N aromatics), 1056.9 cm-1 (C-O phenol), 1724.24 cm-1 (C=O), and 1639.38 cm-1 (conjugated C=O with C=C). The Scanning Electron Microscopy (SEM) images of IIP and IIP show that the IIP is seen to have more cavities than NIP. The optimum pH for quantitative Zn(II) retention was 5.5, and the elution was completed with 2 mL of 1.0 mol L-1 nitric acid. The optimum loading rate was 0.5 mL min-1. The recovery of Zn(II) from solution samples after its SPE extraction on IIP with 50-fold theoretical preconcentration was 94.60-104.50%. The LOD and LOQ with 50-fold theoretical preconcentration obtained were 0.0073 mg L-1 and 0.0244 mg L-1, respectively.

Hydrogen Metabolism in Helicobacter pylori Plays a Role in Gastric Carcinogenesis through Facilitating CagA Translocation.

PubMed

Wang, Ge; Romero-Gallo, Judith; Benoit, Stéphane L; Piazuelo, M Blanca; Dominguez, Ricardo L; Morgan, Douglas R; Peek, Richard M; Maier, Robert J

2016-08-16

A known virulence factor of Helicobacter pylori that augments gastric cancer risk is the CagA cytotoxin. A carcinogenic derivative strain, 7.13, that has a greater ability to translocate CagA exhibits much higher hydrogenase activity than its parent noncarcinogenic strain, B128. A Δhyd mutant strain with deletion of hydrogenase genes was ineffective in CagA translocation into human gastric epithelial AGS cells, while no significant attenuation of cell adhesion was observed. The quinone reductase inhibitor 2-n-heptyl-4-hydroxyquinoline-N-oxide (HQNO) was used to specifically inhibit the H2-utilizing respiratory chain of outer membrane-permeabilized bacterial cells; that level of inhibitor also greatly attenuated CagA translocation into AGS cells, indicating the H2-generated transmembrane potential is a contributor to toxin translocation. The Δhyd strain showed a decreased frequency of DNA transformation, suggesting that H. pylori hydrogenase is also involved in energizing the DNA uptake apparatus. In a gerbil model of infection, the ability of the Δhyd strain to induce inflammation was significantly attenuated (at 12 weeks postinoculation), while all of the gerbils infected with the parent strain (7.13) exhibited a high level of inflammation. Gastric cancer developed in 50% of gerbils infected with the wild-type strain 7.13 but in none of the animals infected with the Δhyd strain. By examining the hydrogenase activities from well-defined clinical H. pylori isolates, we observed that strains isolated from cancer patients (n = 6) have a significantly higher hydrogenase (H2/O2) activity than the strains isolated from gastritis patients (n = 6), further supporting an association between H. pylori hydrogenase activity and gastric carcinogenesis in humans. Hydrogen-utilizing hydrogenases are known to be important for some respiratory pathogens to colonize hosts. Here a gastric cancer connection is made via a pathogen's (H. pylori) use of molecular hydrogen, a host microbiome-produced gas. Delivery of the known carcinogenic factor CagA into host cells is augmented by the H2-utilizing respiratory chain of the bacterium. The role of hydrogenase in carcinogenesis is demonstrated in an animal model, whereby inflammation markers and cancer development were attenuated in the hydrogenase-null strain. Hydrogenase activity comparisons of clinical strains of the pathogen also support a connection between hydrogen metabolism and gastric cancer risk. While molecular hydrogen use is acknowledged to be an alternative high-energy substrate for some pathogens, this work extends the roles of H2 oxidation to include transport of a carcinogenic toxin. The work provides a new avenue for exploratory treatment of some cancers via microflora alterations. Copyright © 2016 Wang et al.

The drift-diffusion interpretation of the electron current within the organic semiconductor characterized by the bulk single energy trap level

NASA Astrophysics Data System (ADS)

Cvikl, B.

2010-01-01

The closed solution for the internal electric field and the total charge density derived in the drift-diffusion approximation for the model of a single layer organic semiconductor structure characterized by the bulk shallow single trap-charge energy level is presented. The solutions for two examples of electric field boundary conditions are tested on room temperature current density-voltage data of the electron conducting aluminum/tris(8-hydroxyquinoline aluminum/calcium structure [W. Brütting et al., Synth. Met. 122, 99 (2001)] for which jexp∝Va3.4, within the interval of bias 0.4 V≤Va≤7. In each case investigated the apparent electron mobility determined at given bias is distributed within a given, finite interval of values. The bias dependence of the logarithm of their lower limit, i.e., their minimum values, is found to be in each case, to a good approximation, proportional to the square root of the applied electric field. On account of the bias dependence as incorporated in the minimum value of the apparent electron mobility the spatial distribution of the organic bulk electric field as well as the total charge density turn out to be bias independent. The first case investigated is based on the boundary condition of zero electric field at the electron injection interface. It is shown that for minimum valued apparent mobilities, the strong but finite accumulation of electrons close to the anode is obtained, which characterize the inverted space charge limited current (SCLC) effect. The second example refers to the internal electric field allowing for self-adjustment of its boundary values. The total electron charge density is than found typically to be of U shape, which may, depending on the parameters, peak at both or at either Alq3 boundary. It is this example in which the proper SCLC effect is consequently predicted. In each of the above two cases, the calculations predict the minimum values of the electron apparent mobility, which substantially exceed the corresponding published measurements. For this reason the effect of the drift term alone is additionally investigated. On the basis of the published empirical electron mobilities and the diffusion term revoked, it is shown that the steady state electron current density within the Al/Alq3 (97 nm)/Ca single layer organic structure may well be pictured within the drift-only interpretation of the charge carriers within the Alq3 organic characterized by the single (shallow) trap energy level. In order to arrive at this result, it is necessary that the nonzero electric field, calculated to exist at the electron injecting Alq3/Ca boundary, is to be appropriately accounted for in the computation.

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 and a good linear relationship between the concentration and absorbance was observed in the concentration range 0-0.2 ppm, with a detection limit (S/N=3) of 0.02 ppm. The assembled photometric detector was also applied to the determination of phosphate by the flow injection of river water samples using the reagent solution containing MG and molybdenum ammonium in sulfuric acid. A good recovery (97-99%) for the river water samples, which had been spiked with the standard 0.08 ppm, with an RSD of ca 5% (n=5) was obtained using the constructed system. Copyright © 2014 Elsevier B.V. All rights reserved.

P3HT:PCBM-based organic solar cells : Optimisation of active layer nanostructure and interface properties

NASA Astrophysics Data System (ADS)

Kadem, Burak Yahya

Organic solar cells (OSCs) have attracted a significant attention during the last decade due to their simple processability on a flexible substrate as well as scope for large-scale production using role to role technique. Improving the performance of the organic solar cells and their lifetime stability are one of the main challenges faced by researchers in this field. In this thesis, work has been carried out using a blend of Poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-Phenyl C[61] butyric acid methyl ester (PCBM) as an active layer in the ratio of (1:1) (P3HT:PCBM). The efficiency and stability of P3HT:PCBM-based solar cells have been examined using different methods and employing novel materials such as1-[N-(2-ethoxyethyl) pent-4-ynamide] -8 (11), 15 (18), 22 (25) -tris-{2-[2-(2-ethoxyethoxy) ethoxy]-1-[2-((2- ethoxyethoxy) - ethoxy) methyl] ethyloxy} phthalocyaninato zinc (II) (ZnPc) to construct a ternary hybrid as the active layer. Controlling the morphology and crystallinity of P3HT:PCBM active layer was carried out using different solvents including chloroform (CF), chlorobenzene (CB) and dichlorobenzene (DCB) and their co-solvents in the ratio of (1:1) to dissolve the P3HT:PCBM blend. Optimum morphology and crystallinity were achieved using a co-solvent made of CB:CF with the obtained solar cell exhibiting the highest performance with PCE reaching 2.73% among other devices prepared using different solvents. Further device performance improvement was observed through optimization of active layer thickness with studied thickness falling in range 65-266 nm. Measurements of the PV characteristics of the investigated OSC devices have revealed optimum performance when active layer thickness was 95 nm with PCE=3.846%. The stability of the P3HT:PCBM-based devices on optimisation of the active layer thickness has shown a decrease in PCE of about 71% over a period of 41 days. Furthermore, P3HT has been blended with different fullerene derivatives (PC[60]BM, PC[61]BM, PC[70]BM and PC[71]BM) and the active layers were processed using the optimum solvent as well as optimum film's thickness.These PCBM derivatives have different lower unoccupied molecular level (LUMO) and different higher occupied molecular level (HOMO) positions, which subsequently influence the PV parameters of the OSCs such as the device open circuit voltage (V[oc]) and its built-in potential (V[bi]). P3HT:PC61BM-based blend has exhibited the highest device performance with PCE reaching 4.2%. Using the above mentioned optimum parameters, the P3HT:PCBM-based devices have been subjected to post-deposition annealing at different temperatures in the range 100-180°C. Efficient device performance was ascribed to P3HT:PCBM layers being subjected to post-deposition heat treatment at 140°C with PCE=5.5%. Device stability as a result of post-deposition heat treatment has also been shown to improve with PCE degrading by about 38% after 55 days.The use of interfacial layer is found to play a key part in modifying the solar cell performance; using electron transport layer (ETL) such as aluminium tris(8-hydroxyquinoline) (Alq3) as a solution processable layer has contributed in increasing PCE to 4.25%, while, using PEDOT:PSS as a hole transport layer (HTL) doped with metal salts has significantly contributed in increasing PCE to reach 6.82% in device when PEDOT:PSS was doped with LiCl aqueous solution. Stability study for the device based on HTL has shown degradation in the PCE from 6.82% to around 1% over 96 days. Using ETL and HTL simultaneously in a complete device has shown a further enhanced PCE reaching 7%. In a further study, doping the P3HT:PCBM with the novel ZnPc hybrids (SWCNTs and reduced graphene oxide (rGO) are covalently and non-covalently functionalised to ZnPc) with the weight ratio of (1:0.01) has significantly altered the solar cell device properties. The best performance is based on P3HT:PCBM blended with ZnPc-SWCNTs-co bonded as a ternary active layer demonstrating device PCE of 5.3% compared to a reference device based on bare P3HT:PCBM blend with PCE of 3.46%.

Defect analysis in low temperature atomic layer deposited Al{sub 2}O{sub 3} and physical vapor deposited SiO barrier films and combination of both to achieve high quality moisture barriers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maindron, Tony, E-mail: tony.maindron@cea.fr; Jullien, Tony; André, Agathe

2016-05-15

Al{sub 2}O{sub 3} [20 nm, atomic layer deposition (ALD)] and SiO films' [25 nm, physical vacuum deposition (PVD)] single barriers as well as hybrid barriers of the Al{sub 2}O{sub 3}/SiO or SiO/Al{sub 2}O{sub 3} have been deposited onto single 100 nm thick tris-(8-hydroxyquinoline) aluminum (AlQ{sub 3}) organic films made onto silicon wafers. The defects in the different barrier layers could be easily observed as nonfluorescent AlQ{sub 3} black spots, under ultraviolet light on the different systems stored into accelerated aging conditions (85 °C/85% RH, ∼2000 h). It has been observed that all devices containing an Al{sub 2}O{sub 3} layer present a lag time τ frommore » which defect densities of the different systems start to increase significantly. This is coherent with the supposed pinhole-free nature of fresh, ALD-deposited, Al{sub 2}O{sub 3} films. For t > τ, the number of defect grows linearly with storage time. For devices with the single Al{sub 2}O{sub 3} barrier layer, τ has been estimated to be 64 h. For t > τ, the defect occurrence rate has been calculated to be 0.268/cm{sup 2}/h. Then, a total failure of fluorescence of the AlQ{sub 3} film appears between 520 and 670 h, indicating that the Al{sub 2}O{sub 3} barrier has been totally degraded by the hot moisture. Interestingly, the device with the hybrid barrier SiO/Al{sub 2}O{sub 3} shows the same characteristics as the device with the single Al{sub 2}O{sub 3} barrier (τ = 59 h; 0.246/cm{sup 2}/h for t > τ), indicating that Al{sub 2}O{sub 3} ALD is the factor that limits the performance of the barrier system when it is directly exposed to moisture condensation. At the end of the storage period (1410 h), the defect density for the system with the hybrid SiO/Al{sub 2}O{sub 3} barrier is 120/cm{sup 2}. The best sequence has been obtained when Al{sub 2}O{sub 3} is passivated by the SiO layer (Al{sub 2}O{sub 3}/SiO). In that case, a large lag time of 795 h and a very low defect growth rate of 0.032/cm{sup 2}/h (t > τ) have been measured. At the end of the storage test (2003 h), the defect density remains very low, i.e., only 50/cm{sup 2}. On the other hand, the device with the single PVD-deposited SiO barrier layer shows no significant lag time (τ ∼ 0), and the number of defects grows linearly from initial time with a high occurrence rate of 0.517/cm{sup 2}/h. This is coherent with the pinhole-full nature of fresh, PVD-deposited, SiO films. At intermediate times, a second regime shows a lower defect occurrence rate of 0.062/cm{sup 2}/h. At a longer time span (t > 1200 h), the SiO barrier begins to degrade, and a localized crystallization onto the oxide surface, giving rise to new defects (occurrence rate 0.461/cm{sup 2}/h), could be observed. At the end of the test (2003 h), single SiO films show a very high defect density of 600/cm{sup 2}. Interestingly, the SiO surface in the Al{sub 2}O{sub 3}/SiO device does not appeared crystallized at a high time span, suggesting that the crystallization observed on the SiO surface in the AlQ{sub 3}/SiO device rather originates into the AlQ{sub 3} layer, due to high humidity ingress on the organic layer through SiO pinholes. This has been confirmed by atomic force microscopy surface imaging of the AlQ{sub 3}/SiO surface showing a central hole in the crystallization zone with a 60 nm depth, deeper than SiO thickness (25 nm). Using the organic AlQ{sub 3} sensor, the different observations made in this work give a quantitative comparison of defects' occurrence and growth in ALD-deposited versus PVD-deposited oxide films, as well as in their combination PVD/ALD and ALD/PVD.« less