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Sample records for 1,2-ethanedithiol

  1. An Improved Synthesis of Arsenic-Biotin Conjugates

    Heredia-Moya, Jorge; KIRK, KENNETH L.

    2008-01-01

    An amide linked conjugate of p-aminophenylarsine oxide and biotin is conveniently prepared in a one-pot procedure by reaction of biotinyl chloride, formed in situ, with p-aminophenyldichloroarsine. Reaction of the arsine oxide-biotin conjugate with 1,2-ethanedithiol produces the stabilized dithiarsolane. These reagents are now readily available for a variety of applications.

  2. 2-(p-Hydroxybenzyl)indoles - Side Products Formed Upon Cleavage of Indole Derivatives from Carboxylated Wang Polymer - an NMR Study

    Wikberg, Jarl E. S.; Larisa Borisova-Jan; Aleh Yahorau; Sviatlana Yahorava; Jana Kreicberga; Ilze Mutule; Máté Erdélyi; Felikss Mutulis

    2003-01-01

    Treatment of carboxylated Wang polymer attached to a 2-unsubstituted indole derivative with a trifluoroacetic acid based mixture resulted in a side reaction: p-hydroxybenzylation at the 2-position of the indole ring. The structure of the resulting N-3-aminopropyl)-N-benzyl-4-[2-(4-hydroxybenzyl)-1H-indol-3-yl]-butyramide trifluoroacetate was ascertained by a full assignment of its 1H- and 13C-NMR spectra. The side reaction could be suppressed by the use of 1,2-ethanedithiol in high concentrat...

  3. Tethered Transition Metals Promoted Photocatalytic System for Efficient Hydrogen Evolutions

    Takanabe, Kazuhiro

    2015-03-05

    The present invention is directed, at least in part, to a process for improving the efficiency of a photocatalyst (a semiconductor photocatalyst) by tethering (depositing) a metal (e.g., metal ions of a late transition metal, such as nickel) to the semiconductor (photocatalyst) surface through the use of an organic ligand. More specifically, 1,2-ethanedithiol (EDT) functions as an excellent molecular linker (organic ligand) to attach a transition metal complex (e.g., nickel (Ni.sup.2+ ions)) to the semiconductor surface, which can be in the form of a cadmium sulfide surface. The photocatalyst has particular utility in generating hydrogen from H.sub.2S.

  4. 甘氨酸对美拉德反应体系及产生肉香风味物质的影响%Effect of Glycine on Maillard Reaction System and Meat Flavor Compounds

    曾茂茂; 李伶俐; 何志勇; 秦昉; 陈洁

    2012-01-01

    研究添加甘氨酸对葡萄糖.半胱氨酸的简单美拉德反应体系中底物残留浓度、pH值、颜色物质以及产生肉香味的1,2-乙二硫醇、2-乙基吡嗪、2,4,5-三甲基噻唑和2-乙酰基呋喃4种风味化合物的影响。结果表明:随着甘氨酸加入量的增加,体系中半胱氨酸浓度基本不变,而葡萄糖的浓度则略有下降;体系中产生了大量颜色物质,并且pH值变小;1,2-乙二硫醇与2,4,5.三甲基噻唑的浓度均先增大后减小,2-乙基吡嗪的含量逐渐降低,2-乙酰基呋喃的浓度先增大后基本保持不变。感官评定的结果表明,当甘氨酸的添加浓度为0.20mol/L时,体系整体的肉香味有所提高。%The effect of glycine addition on the residual substrate concentration, pH and color of a glucose-cysteine Maillard reaction system as well as meat flavor compounds including 1,2-ethanedithiol, 2-ethylpyrazine, 2,4,5-trimethylthiazole and 2- acetylfuran was investigated. The results demonstrated that with increasing glycine addition, residual cysteine concentration remained basically unchanged, while residual glucose concentration slightly decreased. Besides, large amounts of colored compounds were formed, and the pH became lower. Meanwhile, both 1, 2-ethanedithiol and 2, 4, 5-trimethylthiazole exhibited an initial increase and subsequent decrease, 2-ethylpyrazine revealed a gradual decrease, and 2-acetylfuran revealed an increase first and then remained basically unchanged. As for sensory evaluation, the meat flavor of the system revealed an increase due to the addition of glycine at 0.20 mol/L.

  5. Structure/Processing Relationships of Highly Ordered Lead Salt Nanocrystal Superlattices

    Hanrath, Tobias

    2009-10-27

    We investigated the influence of processing conditions, nanocrystal/substrate interactions and solvent evaporation rate on the ordering of strongly interacting nanocrystals by synergistically combining electron microscopy and synchrotron-based small-angle X-ray scattering analysis. Spin-cast PbSe nanocrystal films exhibited submicrometer-sized supracrystals with face-centered cubic symmetry and (001)s planes aligned parallel to the substrate. The ordering of drop-cast lead salt nanocrystal films was sensitive to the nature of the substrate and solvent evaporation dynamics. Nanocrystal films drop-cast on rough indium tin oxide substrates were polycrystalline with small grain size and low degree of orientation with respect to the substrate, whereas films drop-cast on flat Si substrates formed highly ordered face-centered cubic supracrystals with close-packed (111)s planes parallel to the substrate. The spatial coherence of nanocrystal films drop-cast in the presence of saturated solvent vapor was significantly improved compared to films drop-cast in a dry environment. Solvent vapor annealing was demonstrated as a postdeposition technique to modify the ordering of nanocrystals in the thin film. Octane vapor significantly improved the long-range order and degree of orientation of initially disordered or polycrystalline nanocrystal assemblies. Exposure to 1,2-ethanedithiol vapor caused partial displacement of surface bound oleic acid ligands and drastically degraded the degree of order in the nanocrystal assembly. © 2009 American Chemical Society.

  6. Oligomerization of Indole Derivatives with Incorporation of Thiols

    Jarl E.S. Wikberg

    2008-08-01

    Full Text Available Abstract: Two molecules of indole derivative, e.g. indole-5-carboxylic acid, reacted with one molecule of thiol, e.g. 1,2-ethanedithiol, in the presence of trifluoroacetic acid to yield adducts such as 3-[2-(2-amino-5-carboxyphenyl-1-(2-mercaptoethylthioethyl]-1Hindole-5-carboxylic acid. Parallel formation of dimers, such as 2,3-dihydro-1H,1'H-2,3'-biindole-5,5'-dicarboxylic acid and trimers, such as 3,3'-[2-(2-amino-5-carboxyphenyl ethane-1,1-diyl]bis(1H-indole-5-carboxylic acid of the indole derivatives was also observed. Reaction of a mixture of indole and indole-5-carboxylic acid with 2-phenylethanethiol proceeded in a regioselective way, affording 3-[2-(2-aminophenyl-1-(phenethylthioethyl]-1H-indole-5-carboxylic acid. An additional product of this reaction was 3-[2-(2-aminophenyl-1-(phenethylthioethyl]-2,3-dihydro-1H,1'H-2,3'-biindole-5'-carboxylic acid, which upon standing in DMSO-d6 solution gave 3-[2-(2-aminophenyl-1-(phenethylthioethyl]-1H,1'H-2,3'-biindole-5'-carboxylic acid. Structures of all compounds were elucidated by NMR, and a mechanism for their formation was suggested.

  7. Improved performance of nanowire–quantum-dot–polymer solar cells by chemical treatment of the quantum dot with ligand and solvent materials

    We report a nanowire–quantum-dot–polymer solar cell consisting of a chemically treated CdSe quantum dot film deposited on n-type ZnO nanowires. The electron and hole collecting contacts are a fluorine-doped tin-oxide/zinc oxide layer and a P3HT/Au layer. This device architecture allows for enhanced light absorption and an efficient collection of photogenerated carriers. A detailed analysis of the chemical treatment of the quantum dots, their deposition, and the necessary annealing processes are discussed. We find that the surface treatment of CdSe quantum dots with pyridine, and the use of 1,2-ethanedithiol (EDT) ligands, critically improves the device performance. Annealing at 380 °C for 2 h is found to cause a structural conversion of the CdSe from its initial isolated quantum dot arrangement into a polycrystalline film with excellent surface conformality, thereby resulting in a further enhancement of device performance. Moreover, long-term annealing of 24 h leads to additional increases in device efficiency. Our best conversion efficiency reached for this type of cell is 3.4% under 85 mW cm−2 illumination. (paper)

  8. Ethanedithiol-treated manganese oxide nanoparticles for rapidly responsive and transparent supercapacitors

    Ryu, Ilhwan; Kim, Green; Park, Dasom; Yim, Sanggyu

    2015-11-01

    Metal oxide nanoparticles (NPs) provide a large surface area and short diffusion pathways for ions in supercapacitor electrode materials. However, binders and conductive additives used for tight connections with current collectors and improved conductivity hamper these benefits. In this work, we successfully fix manganese oxide (Mn3O4) NPs onto ITO current collectors by a simple 1,2-ethanedithiol (EDT) treatment without using any binders or conductive additives. As compared to the electrode fabricated using binder-mixed Mn3O4 NPs, the EDT-treated electrode shows significantly improved specific capacitance of 403 F g-1 at a scan rate of 10 mV s-1. The EDT-treatment is more effective at higher scan rates. The specific capacitances, 278 F g-1 at 100 mV s-1 and 202 F g-1 at 200 mV s-1, are larger than those reported so far at scan rates ≥100 mV s-1. The deconvolution of capacitive elements indicates that these improved capacitive properties are attributed to large insertion elements of the binder-free NP electrodes. Furthermore, this additive-free electrode is highly transparent and can be easily fabricated by simple spray-coating on various substrates including polymer films, implying that this new method is promising for the fabrication of large-area, transparent and flexible electrodes for next-generation supercapacitors.

  9. Improved performance of nanowire-quantum-dot-polymer solar cells by chemical treatment of the quantum dot with ligand and solvent materials

    Nadarajah, A.; Smith, T.; Könenkamp, R.

    2012-12-01

    We report a nanowire-quantum-dot-polymer solar cell consisting of a chemically treated CdSe quantum dot film deposited on n-type ZnO nanowires. The electron and hole collecting contacts are a fluorine-doped tin-oxide/zinc oxide layer and a P3HT/Au layer. This device architecture allows for enhanced light absorption and an efficient collection of photogenerated carriers. A detailed analysis of the chemical treatment of the quantum dots, their deposition, and the necessary annealing processes are discussed. We find that the surface treatment of CdSe quantum dots with pyridine, and the use of 1,2-ethanedithiol (EDT) ligands, critically improves the device performance. Annealing at 380 °C for 2 h is found to cause a structural conversion of the CdSe from its initial isolated quantum dot arrangement into a polycrystalline film with excellent surface conformality, thereby resulting in a further enhancement of device performance. Moreover, long-term annealing of 24 h leads to additional increases in device efficiency. Our best conversion efficiency reached for this type of cell is 3.4% under 85 mW cm-2 illumination.

  10. Influence of interparticle electronic coupling on the temperature and size dependent optical properties of lead sulfide quantum dot thin films

    Roland, Paul J.; Bhandari, Khagendra P.; Ellingson, Randy J.

    2016-03-01

    We report on the quantum dot (QD) size, temperature, and inter-dot coupling dependence on the optical absorption and emission for PbS QD thin films. Inter-dot coupling is induced by ligand exchange from oleic acid to 1,2-ethanedithiol, and the expected band gap red-shift observed for coupled QD thin films is accompanied by a modification to the temperature-dependence of the band gap energy. The amplitude and temperature dependence of the photoluminescence (PL) Stokes shift support recombination via a mid-gap state and also indicate that the application of band gap-specific models to fit the temperature dependence PL peak energy is inadequate. Electronically coupled QD thin films show PL quenching with decreasing temperature, following a Boltzmann model which is consistent with thermally activated carrier transport. Enhancing the inter-dot coupling results in the dynamic PL decay signal changing from single- to bi-exponential behavior, reveals a size-dependent transport activation energy, and yields a negative temperature dependent band gap energy for the smallest QD diameters.

  11. Atomic layer deposition effect on the electrical properties of Al{sub 2}O{sub 3}-passivated PbS quantum dot field-effect transistors

    So, Hye-Mi; Shim, Hyung Cheoul [Department of Nano Mechanics, Nanomechanical Systems Research Division, Korea Institute of Machinery and Materials (KIMM), 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 305-343 (Korea, Republic of); Choi, Hyekyoung; Lee, Seung-Mo; Jeong, Sohee; Chang, Won Seok, E-mail: paul@kimm.re.kr [Department of Nano Mechanics, Nanomechanical Systems Research Division, Korea Institute of Machinery and Materials (KIMM), 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 305-343 (Korea, Republic of); Department of Nano-Mechatronics, Korea University of Science and Technology (UST), 217 Gajeong-Ro, Yuseong-Gu, Daejeon 305-333 (Korea, Republic of)

    2015-03-02

    We have investigated the effect of atomic layer deposition (ALD) on the electrical properties of colloidal PbS quantum dot field-effect transistors (PbS QD-FETs). Low-temperature Al{sub 2}O{sub 3} ALD process was used to fill up the pore spaces of PbS QD films containing 1, 2-ethanedithiol ligands. Upon deposition of Al{sub 2}O{sub 3} on PbS film, the PbS QD-FETs showed ambipolar behavior. The treated film retained this property for over 2 months, despite of exposure to air. This change in the electrical properties of the PbS QD-FETs is attributed to the formation of electron channels in the Al{sub 2}O{sub 3}-passivated PbS film. We conclude that these electron transport channels in the Al{sub x}O{sub y}-PbS film are formed due to substitution of the Pb sites by Al metal and chemical reduction of Pb{sup 2+} ions, as determined by an analysis of the depth profile of the film using secondary ion mass spectrometry and X-ray photoelectron spectroscopy.

  12. Phosphoprotein Isotope-Coded Solid-Phase Tag Approach for Enrichment and Quantitative Analysis of Phosphopeptides from Complex Mixtures

    Qian, Weijun (BATTELLE (PACIFIC NW LAB)); Goshe, Michael B.(North Carolina State University); Camp, David G.(BATTELLE (PACIFIC NW LAB)); Yu, Li-Rong (BATTELLE (PACIFIC NW LAB)); Tang, Keqi (BATTELLE (PACIFIC NW LAB)); Smith, Richard D.(BATTELLE (PACIFIC NW LAB))

    2003-10-15

    Many cellular processes are regulated by reversible protein phosphorylation and the ability to identify and quantify phosphoproteins from proteomes is essential for gaining a better understanding of these dynamic cellular processes. However, a sensitive, efficient and global method capable of addressing the phosphoproteome has yet to be developed. Here we describe an improved stable-isotope labeling method using a Phosphoprotein Isotope-coded Solid-phase Tag (PhIST) for isolating and measuring the relative abundance of phosphorylated peptides from complex peptide mixtures resulting from the enzymatic digestion of extracted proteins. The PhIST approach is an extension of the previously reported Phosphoprotein Isotope-coded Affinity Tag (PhIAT)approach developed by our laboratory1-2, where the O-phosphate moiety on phosphoseryl or phosphothreonyl residues were derivatized by hydroxide ion-medated B-elimination followed by the addition of 1,2-ethanedithiol (EDT). Instead of using the biotin affinity tag, peptides containing the EDT moiety were captured and labeled in one step using isotope-coded solid-phase reagents containing either light (12C6, 14N) or heavy (13C6, 15N) stable isotopes. The captured peptides labeled with the isotope-coded tags were released from the solid-phase support by UV photocleavage and analyzed by capillary LC-MS/MS. The efficiency and sensitivity of the PhIST labeling approach for identification of phosphopeptides from mixtures was demonstrated using casein phosphoproteins. Its utility for proteomic applications is demonstrated by the labeling of soluble proteins from human breast cancer cell line.

  13. Revisiting the Valence and Conduction Band Size Dependence of PbS Quantum Dot Thin Films

    Miller, Elisa M.; Kroupa, Daniel M.; Zhang, Jianbing; Schulz, Philip; Marshall, Ashley R.; Kahn, Antoine; Lany, Stephan; Luther, Joseph M.; Beard, Matthew C.; Perkins, Craig L.; van de Lagemaat, Jao

    2016-03-22

    We use a high signal-to-noise X-ray photoelectron spectrum of bulk PbS, GW calculations, and a model assuming parabolic bands to unravel the various X-ray and ultraviolet photoelectron spectral features of bulk PbS as well as determine how to best analyze the valence band region of PbS quantum dot (QD) films. X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) are commonly used to probe the difference between the Fermi level and valence band maximum (VBM) for crystalline and thin-film semiconductors. However, we find that when the standard XPS/UPS analysis is used for PbS, the results are often unrealistic due to the low density of states at the VBM. Instead, a parabolic band model is used to determine the VBM for the PbS QD films, which is based on the bulk PbS experimental spectrum and bulk GW calculations. Our analysis highlights the breakdown of the Brillioun zone representation of the band diagram for large band gap, highly quantum confined PbS QDs. We have also determined that in 1,2-ethanedithiol-treated PbS QD films the Fermi level position is dependent on the QD size; specifically, the smallest band gap QD films have the Fermi level near the conduction band minimum and the Fermi level moves away from the conduction band for larger band gap PbS QD films. This change in the Fermi level within the QD band gap could be due to changes in the Pb:S ratio. In addition, we use inverse photoelectron spectroscopy to measure the conduction band region, which has similar challenges in the analysis of PbS QD films due to a low density of states near the conduction band minimum.