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Sample records for ranges palladium incorporation

  1. The study of palladium ions incorporation into the mesoporous ordered silicates

    Energy Technology Data Exchange (ETDEWEB)

    Zienkiewicz-Strzalka, M., E-mail: gosiazienkiewicz@wp.pl [Department of Crystallography, Faculty of Chemistry, Maria Curie-Sklodowska University, Sq. Maria Curie-Sklodowska 3, 20-031 Lublin (Poland); Pikus, S., E-mail: stanpik1@wp.pl [Department of Crystallography, Faculty of Chemistry, Maria Curie-Sklodowska University, Sq. Maria Curie-Sklodowska 3, 20-031 Lublin (Poland)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Palladium containing mesoporous ordered silica were synthesized and characterized. Black-Right-Pointing-Pointer Detailed analysis of chemical bonding between palladium and silica was performed. Black-Right-Pointing-Pointer Proposed procedure allows to obtain materials where palladium is binding with silicon and oxygen atoms. - Abstract: In this work mesoporous ordered silica materials containing palladium species were prepared using of tetraammine palladium chloride ([Pd(NH{sub 3}){sub 4}]Cl{sub 2}) complex as a palladium source during synthesis and by wetness impregnation of pure support by solution containing dissolved metal salt. The ammonia ligands from tetraammine palladium chloride were removed during calcination or during thermal treatment at 300 Degree-Sign C in oxygen atmosphere. For reduction of palladium ions to metallic state as prepared materials were treated by hydrogen at high temperature. In this work the locations of palladium atoms in silica lattice were considered by study of binding energy changes of cardinal atoms of mesoporous ordered silica. Ordered mesoporous silicates (MCM-41 and SBA-15) are very promising materials for a wide range of industrial applications due to their unique properties as well-defined ordered structure and excellent textural properties. They exhibit high surface area with high pore volume. Such supports ensure a high dispersion of the metal nanoparticles or other active phases providing the high activity of solid catalysts. The obtained materials were characterized primarily by X-ray diffraction (XRD) technique, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption isotherms, and infrared spectroscopy. The proportional content of palladium was controlled by X-ray fluorescence technique.

  2. Ex Situ Generation of Stoichiometric and Substoichiometric 12CO and 13CO and Its Efficient Incorporation in Palladium Catalyzed Aminocarbonylations

    DEFF Research Database (Denmark)

    Hermange, Philippe; Lindhardt, Anders Thyboe; Taaning, Rolf Hejle

    2011-01-01

    aimed toward application of CO as the limiting reagent, this method provided highly efficient palladium catalyzed aminocarbonylations with CO-incorporations up to 96%. The ex situ generated CO and the two-chamber system were tested in the synthesis of several compounds of pharmaceutical interest and all...... is safely handled and stored. Furthermore, since the CO is generated ex situ, excellent functional group tolerance is secured in the carbonylation chamber. Finally, CO is only generated and released in minute amounts, hence, eliminating the need for specialized equipment such as CO-detectors and equipment...

  3. Removal of diatrizoate with catalytically active membranes incorporating microbially produced palladium nanoparticles.

    Science.gov (United States)

    Hennebel, Tom; De Corte, Simon; Vanhaecke, Lynn; Vanherck, Katrien; Forrez, Ilse; De Gusseme, Bart; Verhagen, Pieter; Verbeken, Kim; Van der Bruggen, Bart; Vankelecom, Ivo; Boon, Nico; Verstraete, Willy

    2010-03-01

    There is an increasing concern about the fate of iodinated contrast media (ICM) in the environment. Limited removal efficiencies of currently applied techniques such as advanced oxidation processes require more performant strategies. The aim of this study was to establish an innovative degradation process for diatrizoate, a highly recalcitrant ICM, by using biogenic Pd nanoparticles as free suspension or immobilized in polyvinylidene fluoride (PVDF) and polysulfone (PSf) membranes. As measured by HPLC-UV, the removal of 20mg L(-1) diatrizoate by a 10mg L(-1) Pd suspension was completed after 4h at a pH of 10. LC-MS analysis provided evidence for the sequential hydrodeiodination of diatrizoate. Pd did not lose its activity after incorporation in the PVDF and PSf matrix and the highest activity (k(cat)=30.0+/-0.4h(-1) L g(-1) Pd) was obtained with a casting solution of 10% PSf and 500mg L(-1) Pd. Subsequently, water containing 20mg L(-1) diatrizoate was treated in a membrane contactor, in which the water was supplied at one side of the membrane while hydrogen was provided at the other side. In a fed batch configuration, a removal efficiency of 77% after a time period of 48h was obtained. This work showed that membrane contactors with encapsulated biogenic nanoparticles can be instrumental for treatment of water contaminated with diatrizoate. Copyright 2009 Elsevier Ltd. All rights reserved.

  4. Palladium-Catalyzed Aerobic Dehydrogenation of Substituted Cyclohexanones to Phenols

    National Research Council Canada - National Science Library

    Yusuke Izawa; Doris Pun; Shannon S. Stahl

    2011-01-01

    .... Here, we report a palladium(II) catalyst system, incorporating an unconventional ortho-dimethylaminopyridine ligand, for the conversion of substituted cyclohexanones to the corresponding phenols...

  5. Incorporating climate change into conservation planning: Identifying priority areas across a species’ range

    Directory of Open Access Journals (Sweden)

    Richard G Pearson

    2012-12-01

    Full Text Available Theoretical and practical approaches associated with conservation biogeography, including ecological niche modeling, have been applied to the difficult task of determining how to incorporate climate change into conservation prioritization methodologies. Most studies have focused on identifying species that are most at risk from climate change, but here we asked, which areas within a species’ range does climate change threaten most? We explored methods for incorporating climate change within a range-wide conservation planning framework, using a case study of jaguars (Panthera onca. We used ecological niche models to estimate exposure to climate change across the range of the jaguar and incorporated these estimates into habitat quality scores for re-prioritization of high-priority areas for jaguar conservation. Methods such as these are needed to guide prioritization of geographically-specific actions for conservation across a species’ range.

  6. Efficient synthesis of π-conjugated molecules incorporating fluorinated phenylene units through palladium-catalyzed iterative C(sp2–H bond arylations

    Directory of Open Access Journals (Sweden)

    Fatiha Abdelmalek

    2015-10-01

    Full Text Available We report herein a two or three step synthesis of fluorinated π-conjugated oligomers through iterative C–H bond arylations. Palladium-catalyzed desulfitative arylation of heteroarenes allowed in a first step the synthesis of fluoroaryl-heteroarene units in high yields. Then, the next steps involve direct arylation with aryl bromides catalyzed by PdCl(C3H5(dppb to afford triad or tetrad heteroaromatic compounds via regioselective activation of C(sp2–H bonds.

  7. MONTANA PALLADIUM RESEARCH INITIATIVE

    Energy Technology Data Exchange (ETDEWEB)

    Peters, John; McCloskey, Jay; Douglas, Trevor; Young, Mark; Snyder, Stuart; Gurney, Brian

    2012-05-09

    Project Objective: The overarching objective of the Montana Palladium Research Initiative is to perform scientific research on the properties and uses of palladium in the context of the U.S. Department of Energy's Hydrogen, Fuel Cells and Infrastructure Technologies Program. The purpose of the research will be to explore possible palladium as an alternative to platinum in hydrogen-economy applications. To achieve this objective, the Initiatives activities will focus on several cutting-edge research approaches across a range of disciplines, including metallurgy, biomimetics, instrumentation development, and systems analysis. Background: Platinum-group elements (PGEs) play significant roles in processing hydrogen, an element that shows high potential to address this need in the U.S. and the world for inexpensive, reliable, clean energy. Platinum, however, is a very expensive component of current and planned systems, so less-expensive alternatives that have similar physical properties are being sought. To this end, several tasks have been defined under the rubric of the Montana Palladium Research Iniative. This broad swath of activities will allow progress on several fronts. The membrane-related activities of Task 1 employs state-of-the-art and leading-edge technologies to develop new, ceramic-substrate metallic membranes for the production of high-purity hydrogen, and develop techniques for the production of thin, defect-free platinum group element catalytic membranes for energy production and pollution control. The biomimetic work in Task 2 explores the use of substrate-attached hydrogen-producing enzymes and the encapsulation of palladium in virion-based protein coats to determine their utility for distributed hydrogen production. Task 3 work involves developing laser-induced breakdown spectroscopy (LIBS) as a real-time, in situ diagnostic technique to characterize PGEs nanoparticles for process monitoring and control. The systems engineering work in task 4

  8. Palladium model catalysts

    NARCIS (Netherlands)

    Voogt, Edwin Herman

    1997-01-01

    This thesis is concerned with the oxidation and reduction of palladium and the adsorption and oxidation of carbon monoxide on palladium. Both subjects are closely related to each other by the background studies needed for the research on these two

  9. Synthesis of azamacrocycle stabilized palladium nanoparticles ...

    Indian Academy of Sciences (India)

    Palladium nanoparticles (PdNPs) of uniform size in the range of 3-5 nm are prepared in MeOH and MeCN:MeOH by solvent-assisted reduction of palladium acetate in the presence of a hexaazamacrocyclic ligand, L1. For the mixed solvent system different ratio of the solvents was tried i.e., 1:1, 1:3 and 3:1. In all cases the ...

  10. Metal allergen of the 21st century--a review on exposure, epidemiology and clinical manifestations of palladium allergy

    DEFF Research Database (Denmark)

    Faurschou, Annesofie; Menné, Torkil; Johansen, Jeanne D

    2011-01-01

    Consumers are mainly exposed to palladium from jewellery and dental restorations. Palladium contact allergy is nearly always seen together with nickel allergy, as palladium and nickel tend to cross-react. We aimed to analyse the available palladium patch test data and case reports to determine...... whether the prevalence of palladium mono-sensitization has increased. Based on available patch test data from the period 1986-2008, a total of 10 778 patients were patch tested with palladium chloride. The median prevalence of palladium allergy was 7.8% (range...

  11. Incorporating spatial autocorrelation into species distribution models alters forecasts of climate-mediated range shifts.

    Science.gov (United States)

    Crase, Beth; Liedloff, Adam; Vesk, Peter A; Fukuda, Yusuke; Wintle, Brendan A

    2014-08-01

    Species distribution models (SDMs) are widely used to forecast changes in the spatial distributions of species and communities in response to climate change. However, spatial autocorrelation (SA) is rarely accounted for in these models, despite its ubiquity in broad-scale ecological data. While spatial autocorrelation in model residuals is known to result in biased parameter estimates and the inflation of type I errors, the influence of unmodeled SA on species' range forecasts is poorly understood. Here we quantify how accounting for SA in SDMs influences the magnitude of range shift forecasts produced by SDMs for multiple climate change scenarios. SDMs were fitted to simulated data with a known autocorrelation structure, and to field observations of three mangrove communities from northern Australia displaying strong spatial autocorrelation. Three modeling approaches were implemented: environment-only models (most frequently applied in species' range forecasts), and two approaches that incorporate SA; autologistic models and residuals autocovariate (RAC) models. Differences in forecasts among modeling approaches and climate scenarios were quantified. While all model predictions at the current time closely matched that of the actual current distribution of the mangrove communities, under the climate change scenarios environment-only models forecast substantially greater range shifts than models incorporating SA. Furthermore, the magnitude of these differences intensified with increasing increments of climate change across the scenarios. When models do not account for SA, forecasts of species' range shifts indicate more extreme impacts of climate change, compared to models that explicitly account for SA. Therefore, where biological or population processes induce substantial autocorrelation in the distribution of organisms, and this is not modeled, model predictions will be inaccurate. These results have global importance for conservation efforts as inaccurate

  12. Promotion effect of palladium on Co{sub 3}O{sub 4} incorporated within mesoporous MCM-41 silica for CO Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Hassan M.A., E-mail: hassan.hassan@suezuniv.edu.eg [Department of Chemistry, Faculty of Science, Suez University, Suez (Egypt); Institut fur Anorganische Chemie und Strukturchemie, Heinrich-Heine Universitat, Dusseldorf (Germany); Betiha, Mohamed A. [Egyptian Petroleum Research Institute, Cairo 11727, Nasr City, Cairo (Egypt); Elshaarawy, Reda F.M. [Department of Chemistry, Faculty of Science, Suez University, Suez (Egypt); Institut fur Anorganische Chemie und Strukturchemie, Heinrich-Heine Universitat, Dusseldorf (Germany); Samy El-Shall, M. [Department of Chemistry, Virginia Commonwealth University Richmond, VA 23284-2006 (United States)

    2017-04-30

    Highlights: • Co{sub 3}O{sub 4} incorporated MCM-41 materials were successfully synthesized using MWI direct approach. • Co3{sup +} cation is considered as favorable site for CO adsorption resulted in promote the CO oxidation. • The loading of Pd species resulted in enhancement of activity for CO oxidation. - Abstract: Co{sub 3}O{sub 4} incorporated within mesoporous MCM-41 silica have been successfully synthesized and promoted with Pd nanoparticles through a microwave irradiation (MWI) approach. Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), N{sub 2}-physisorped, X-ray photoelectron spectroscopy (XPS), temperature program reduction of hydrogen (H{sub 2}-TPR), temperature program desorption of oxygen (O{sub 2}-TPD) and high resolution transmission electron microscopy (HRTEM) were adapted to characterize these prepared catalysts. Carbon monoxide oxidation as a model reaction was then used to assess the catalytic performance of these materials. In the light of H{sub 2}-TPR and XPS results, revealed that the coexisting of Co{sup 3+} and Co{sup 2+} species as well as surface Co{sup 3+}/Co{sup 2+} ratio within the hexagonal mesoporous of MCM-41, could create an ideal environment to accomplish most extreme catalytic activity. On the other hand, the enhanced CO oxidation by Pd nanoparticles deposition has been explained in the light of the enhancement of the redox ability and tuning the electronic structure of Co{sub 3}O{sub 4}, which improved the O{sub 2} activation and reduced the adsorption ability of CO simultaneously, which significantly boosted the catalytic performance of CO oxidation. This work provides insights into factors that could lead to improved low temperature CO oxidation performance in Pd-based catalysts.

  13. Preconcentration and voltammetric determination of palladium (II) at sodium humate modified carbon paste electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Sun Qiaoyu; Wang, C.; Li Liangxi; Li Hulin [Dept. Chemistry, Lanzhou Univ. (China)

    1999-01-01

    A chemically modified carbon paste electrode was prepared by incorporating appropriate amounts of sodium humate(NaA). Palladium(II) was selectively accumulated in a solution of Britton-Robinson(B-R) buffer (pH 2.8) onto the electrode surface in open circuit mode. The subsequent electrochemical measurement was carried out by cyclic voltammetry (CV) and linear sweep anodic stripping voltammetry (LSASV) in a supporting electrolyte of 1.0 M HCl. The obtained oxidation currents (I{sub pa1} and L{sub pa2}) were proportional to the Pd(II) concentration in the range of 4.7 x 10{sup -6} - 9.4 x 10{sup -8} M. The developed method was applied to the quantitative determination of palladium in real samples. (orig.) With 4 figs., 1 tab., 9 refs.

  14. Silver-palladium cathode

    Energy Technology Data Exchange (ETDEWEB)

    Poizot, Philippe [Laboratoire de Reactivite et Chimie des Solides, UMR CNRS 6007, Universite de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cedex (France); Simonet, Jacques, E-mail: jacques.simonet@univ-rennes1.f [Laboratoire MaCSE, UMR CNRS 6226, Universite de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex (France)

    2010-12-15

    The formation of silver-palladium electrodes is described. It mainly corresponds to the palladization of silver by means of treatment with palladium salts (nitrate and sulphate) in acidic media. Other ways may exist such as the modification of solid conductors like carbons by deposition of a silver-palladium alloy. By using those electrodes in polar aprotic solvents, the one-electron cleavage of carbon-halogen bonds of most alkyl iodides and bromides may yield free alkyl radicals. Coupling and cross-coupling reactions can easily be carried out at such electrodes. The present review aims at discussing the electro-catalytic process as well as providing an update on the state of the art on this new mode of scission regarding carbon-heteroatom bonds.

  15. Incorporating latitudinal and central–marginal trends in assessing genetic variation across species ranges

    Science.gov (United States)

    Qinfeng Guo

    2012-01-01

    The genetic variation across a species’ range is an important factor in speciation and conservation, yet searching for general patterns and underlying causes remains challenging. While the majority of comparisons between central and marginal populations have revealed a general central–marginal (C-M) decline in genetic diversity, others show no clear pattern. Similarly...

  16. Phyto-crystallization of palladium through reduction process using Cinnamom zeylanicum bark extract

    Energy Technology Data Exchange (ETDEWEB)

    Sathishkumar, M.; Sneha, K.; Kwak, In Seob; Mao, Juan [Environmental Biotechnology National Research Laboratory, School of Chemical Engineering, Research Institute of Industrial Technology, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Tripathy, S.J. [Nanoparticulate Materials Laboratory, Division of Advanced Materials Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Yun, Y.-S., E-mail: ysyun@chonbuk.ac.kr [Environmental Biotechnology National Research Laboratory, School of Chemical Engineering, Research Institute of Industrial Technology, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2009-11-15

    In this paper we studied the potential of nanocrystalline palladium particle production using Cinnamom zeylanicum bark extract (CBE) as the biomaterial for the first time. We studied the effects of biomaterial dosage, pH and temperature on nanoparticle formation; none of these factors had a major effect on the size and shape of the nanoparticles formed. Transmission electron microscopy (TEM) observations confirmed the synthesis of nano-sized palladium particles. More or less uniformly sized palladium nanoparticles were synthesized with an average size ranging from 15 to 20 nm. It was found that the zeta potential of these formed palladium nanoparticles was negative, and that it increased with an increase in pH. Energy dispersive X-ray (EDX) analysis results confirmed the significant presence of palladium. Of the palladium ions, 60% were reduced to a zero valent form by CBE. Terpenoids are believed to play an important role in palladium nanoparticle biosynthesis through the reduction of palladium ions. Currently, however, the exact mechanism for the synthesis of palladium nanoparticles is unclear. Our protocol for the phyto-synthesis of palladium nanoparticles under moderate pH and room temperature offers a new means to develop environmentally benign nanoparticles.

  17. Palladium catalysis for energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Pfefferle, L. D.; Datye, Abhaya

    2001-03-01

    Palladium (Pd) is an attractive catalyst for a range of new combustion applications comprising primary new technologies for future industrial energy needs, including gas turbine catalytic combustion, auto exhaust catalysts, heating and fuel cells. Pd poses particular challenges because it changes both chemical state and morphology as a function of temperature and reactant environment and those changes result in positive and negative changes in activity. Interactions with the support, additives, water, and contaminants as well as carbon formation have also been observed to affect Pd catalyst performance. This report describes the results of a 3.5 year project that resolves some of the conflicting reports in the literature about the performance of Pd-based catalysis.

  18. Measurement of activation cross-section of long-lived products in deuteron induced nuclear reactions on palladium in the 30-50MeV energy range.

    Science.gov (United States)

    Ditrói, F; Tárkányi, F; Takács, S; Hermanne, A; Ignatyuk, A V

    2017-10-01

    Excitation functions were measured in the 31-49.2MeV energy range for the natPd(d,xn)111,110m,106m,105,104g,103Ag, natPd(d,x) 111m,109,101,100Pd, natPd(d,x), 105,102m,102g,101m,101g,100,99m,99gRh and natPd(d,x)103,97Ru nuclear reactions by using the stacked foil irradiation technique. The experimental results are compared with our previous results and with the theoretical predictions calculated with the ALICE-D, EMPIRE-D and TALYS (TENDL libraries) codes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Incorporation of planetary boundary layer dynamics in a numerical model of long-range air-pollutant transport

    Science.gov (United States)

    Syrakov, D.; Djolov, G.; Yordanov, D.

    1983-05-01

    A numerical model of long-range air-pollutant transport is developed, in which a simple planetary boundary layer (PBL) is incorporated. The pollution field results from the superposition of discrete ‘puffs’ of pollutants which are emitted periodically in different regions. The instantaneous sources in the different cells are approximated by rotational ellipsoids with Gaussian concentration distributions. The puff movement due to the external flow is followed by the displacement of the centroid. The expansion of the puff is modelled by nonisotropic Fickian diffusion. A simple barotropic PBL model is used to study the PBL influence. This model gives the flow velocity and the vertical turbulent exchange coefficient, which depend on the external parameters Ro and S — Rossby number and stratification parameter. The model performance is investigated by special test runs. The dependence of the pollution field on source height, stability conditions and vertical motions is shown.

  20. Hydrogen absorption induced metal deposition on palladium and palladium-alloy particles

    Science.gov (United States)

    Wang, Jia X [East Setauket, NY; Adzic, Radoslav R [East Setauket, NY

    2009-03-24

    The present invention relates to methods for producing metal-coated palladium or palladium-alloy particles. The method includes contacting hydrogen-absorbed palladium or palladium-alloy particles with one or more metal salts to produce a sub-monoatomic or monoatomic metal- or metal-alloy coating on the surface of the hydrogen-absorbed palladium or palladium-alloy particles. The invention also relates to methods for producing catalysts and methods for producing electrical energy using the metal-coated palladium or palladium-alloy particles of the present invention.

  1. Organometallic palladium reagents for cysteine bioconjugation

    Science.gov (United States)

    Vinogradova, Ekaterina V.; Zhang, Chi; Spokoyny, Alexander M.; Pentelute, Bradley L.; Buchwald, Stephen L.

    2015-10-01

    Reactions based on transition metals have found wide use in organic synthesis, in particular for the functionalization of small molecules. However, there are very few reports of using transition-metal-based reactions to modify complex biomolecules, which is due to the need for stringent reaction conditions (for example, aqueous media, low temperature and mild pH) and the existence of multiple reactive functional groups found in biomolecules. Here we report that palladium(II) complexes can be used for efficient and highly selective cysteine conjugation (bioconjugation) reactions that are rapid and robust under a range of bio-compatible reaction conditions. The straightforward synthesis of the palladium reagents from diverse and easily accessible aryl halide and trifluoromethanesulfonate precursors makes the method highly practical, providing access to a large structural space for protein modification. The resulting aryl bioconjugates are stable towards acids, bases, oxidants and external thiol nucleophiles. The broad utility of the bioconjugation platform was further corroborated by the synthesis of new classes of stapled peptides and antibody-drug conjugates. These palladium complexes show potential as benchtop reagents for diverse bioconjugation applications.

  2. Palladium-Polyaniline and Palladium-Polyaniline Derivative Composite Materials

    National Research Council Canada - National Science Library

    Mallick, Kaushik; Witcomb, Michael; Scurrell, Mike

    2007-01-01

    Palladium nanoparticles of different sizes and shapes combined with polyaniline and derivatives of polyaniline can give rise to a host polymer with interesting physical properties and important potential applications...

  3. Occupational asthma caused by palladium

    Energy Technology Data Exchange (ETDEWEB)

    Daenen, M.; Rochette, F.; Demedts, M.; Nemery, B. [K.U. Leuven, Pneumology (Belgium); Rogiers, P. [A.Z. St-Lucas, Brugge (Belgium); Walle, C. Van de [Siemens, Oostkamp (Belgium)

    1999-01-01

    Occupational exposure to complex platinum salts is a well-known cause of occupational asthma. Although there is evidence that platinum refinery workers may also be sensitized to other precious metals, such as palladium or rhodium, no instances of occupational asthma due to an isolated sensitization to palladium have been reported. A case is reported of occupational rhinoconjunctivitis and asthma in a previously healthy worker exposed to the fumes of an electroplating bath containing palladium. There was no exposure to platinum. Sensitization to palladium was documented by skin-prick tests. The skin-prick test was positive with Pd(NH{sub 3}){sub 4}Cl{sub 2}, but not with (NH{sub 4}){sub 2}PdCl{sub 4}. Corresponding salts of platinum were all negative. A bronchial provocation test with Pd(NH{sub 34})Cl{sub 2} (0.0001 % for a total of 315 s, followed by 0.001 % for a total of 210 s) led to an early decrease in forced expiratory volume in one second (-35%). A similar exposure (0.001 % for a total of 16 min) in an unrelated asthmatic gave no reaction. This case shows that an isolated sensitization to palladium can occur and that respiratory exposure to palladium is a novel cause of metal-induced occupational asthma. (au) 24 refs.

  4. Low-cost method for fabricating palladium and palladium-alloy thin films on porous supports

    Science.gov (United States)

    Lee, Tae H; Park, Chan Young; Lu, Yunxiang; Dorris, Stephen E; Balachandran, Uthamalingham

    2013-11-19

    A process for forming a palladium or palladium alloy membrane on a ceramic surface by forming a pre-colloid mixture comprising a powder palladium source, carrier fluid, dispersant and a pore former and a binder. Ultrasonically agitating the precolloid mixture and applying to a substrate with an ultrasonic nozzle and heat curing the coating form a palladium-based membrane.

  5. An expanded Notch-Delta model exhibiting long-range patterning and incorporating MicroRNA regulation.

    Directory of Open Access Journals (Sweden)

    Jerry S Chen

    2014-06-01

    Full Text Available Notch-Delta signaling is a fundamental cell-cell communication mechanism that governs the differentiation of many cell types. Most existing mathematical models of Notch-Delta signaling are based on a feedback loop between Notch and Delta leading to lateral inhibition of neighboring cells. These models result in a checkerboard spatial pattern whereby adjacent cells express opposing levels of Notch and Delta, leading to alternate cell fates. However, a growing body of biological evidence suggests that Notch-Delta signaling produces other patterns that are not checkerboard, and therefore a new model is needed. Here, we present an expanded Notch-Delta model that builds upon previous models, adding a local Notch activity gradient, which affects long-range patterning, and the activity of a regulatory microRNA. This model is motivated by our experiments in the ascidian Ciona intestinalis showing that the peripheral sensory neurons, whose specification is in part regulated by the coordinate activity of Notch-Delta signaling and the microRNA miR-124, exhibit a sparse spatial pattern whereby consecutive neurons may be spaced over a dozen cells apart. We perform rigorous stability and bifurcation analyses, and demonstrate that our model is able to accurately explain and reproduce the neuronal pattern in Ciona. Using Monte Carlo simulations of our model along with miR-124 transgene over-expression assays, we demonstrate that the activity of miR-124 can be incorporated into the Notch decay rate parameter of our model. Finally, we motivate the general applicability of our model to Notch-Delta signaling in other animals by providing evidence that microRNAs regulate Notch-Delta signaling in analogous cell types in other organisms, and by discussing evidence in other organisms of sparse spatial patterns in tissues where Notch-Delta signaling is active.

  6. Biotemplated fabrication of size controlled palladium nanoparticle chains

    NARCIS (Netherlands)

    Zhou, Xingfei; Zheng, Lifei; Li, Rong; Li, Bin; Pillai, Saju; Xu, Peng; Zhang, Yi

    2012-01-01

    Metal nanoparticles exhibit unique size- and spatial organization-dependent physical and chemical properties, and have a wide range of applications in various areas including single electron devices, chemical catalysts and biomedicines. In this paper, chains of palladium nanoparticles were obtained

  7. Synthesis of palladium-doped silica nanofibers by sol-gel reaction and electrospinning process

    Energy Technology Data Exchange (ETDEWEB)

    San, Thiam Hui; Daud, Wan Ramli Wan; Kadhum, Abdul Amir Hassan; Mohamad, Abu Bakar; Kamarudin, Siti Kartom; Shyuan, Loh Kee; Majlan, Edy Herianto [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia and Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2012-06-29

    Nanofiber is drawing great attention nowadays with their high surface area per volume and flexibility in surface functionalities that make them favorable as a proton exchange membrane in fuel cell application. In this study, incorporation of palladium nanoparticles in silica nanofibers was prepared by combination of a tetraorthosilane (TEOS) sol-gel reaction with electrospinning process. This method can prevent the nanoparticles from aggregation by direct mixing of palladium nanoparticles in silica sol. The as-produced electrospun fibers were thermally treated to remove poly(vinyl pyrrolidone) (PVP) and condensation of silanol in silica framework. PVP is chosen as fiber shaping agent because of its insulting and capping properties for various metal nanoparticles. Scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the silica fibers and Pd nanoparticles on the fibers. Spun fibers with average diameter ranged from 100nm to 400nm were obtained at optimum operating condition and distribution of Pd nanoparticles on silica fibers was investigated.

  8. Multiphoton lithography of nanocrystalline platinum and palladium for site-specific catalysis in 3D microenvironments.

    Science.gov (United States)

    Zarzar, Lauren D; Swartzentruber, B S; Harper, Jason C; Dunphy, Darren R; Brinker, C Jeffrey; Aizenberg, Joanna; Kaehr, Bryan

    2012-03-07

    Integration of catalytic nanostructured platinum and palladium within 3D microscale structures or fluidic environments is important for systems ranging from micropumps to microfluidic chemical reactors and energy converters. We report a straightforward procedure to fabricate microscale patterns of nanocrystalline platinum and palladium using multiphoton lithography. These materials display excellent catalytic, electrical, and electrochemical properties, and we demonstrate high-resolution integration of catalysts within 3D defined microenvironments to generate directed autonomous particle and fluid transport. © 2012 American Chemical Society

  9. Palladium Catalyzed Reduction of Nitrobenzene.

    Science.gov (United States)

    Mangravite, John A.

    1983-01-01

    Compares two palladium (Pd/C) reducing systems to iron/tin-hydrochloric acid (Fe/HCl and Sn/HCl) reductions and suggests an efficient, clean, and inexpensive procedures for the conversion of nitrobenzene to aniline. Includes laboratory procedures used and discussion of typical results obtained. (JN)

  10. Sensitization to palladium in Europe

    DEFF Research Database (Denmark)

    Muris, Joris; Goossens, An; Gonçalo, Margarida

    2015-01-01

    BACKGROUND: Recently, sodium tetrachloropalladate (Na2 PdCl4 ) was found to be a more sensitive palladium patch test allergen than palladium dichloride (PdCl2 ). OBJECTIVES: To determine the optimal test concentration of Na2 PdCl4 , to evaluate the prevalence of palladium sensitization with Na2 Pd......Cl4 and PdCl2 , and to compare the results with nickel sensitization in a European multicentre study. MATERIALS AND METHODS: In addition to the European or national baseline series including NiSO4 ·6H2 0 5% pet., consecutive patients were tested with PdCl2 and Na2 PdCl4 2%, 3% and 4% pet. in eight...... European dermatology clinics. The age and sex distributions were also evaluated in patients sensitized to nickel and palladium. RESULTS: In total, 1651 patients were tested. Relative to 3% Na2 PdCl4 , 4% Na2 PdCl4 did not add any information. Two per cent Na2 PdCl4 resulted in more doubtful reactions...

  11. Palladium-Catalysed Coupling Reactions

    NARCIS (Netherlands)

    de Vries, Johannes G.; Beller, M; Blaser, HU

    2012-01-01

    Palladium-catalysed coupling reactions have gained importance as a tool for the production of pharmaceutical intermediates and to a lesser extent also for the production of agrochemicals, flavours and fragrances, and monomers for polymers. In this review only these cases are discussed where it seems

  12. Hydrogen sensor based on a graphene - palladium nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Lange, Ulrich, E-mail: ulrich.lange@chemie.uni-r.d [Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, 93040 Regensburg (Germany); Hirsch, Thomas [Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, 93040 Regensburg (Germany); Mirsky, Vladimir M. [Department of Nanobiotechnology, Lausitz University of Applied Sciences, 01968 Senftenberg (Germany); Wolfbeis, Otto S. [Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, 93040 Regensburg (Germany)

    2011-04-01

    A composite material was prepared from graphene and palladium nanoparticles (PdNP) by layer-by-layer deposition on gold electrodes. The material was characterized by absorption spectroscopy, scanning electron microscopy, Raman spectroscopy and surface plasmon resonance. Cyclic voltammetry demonstrated the presence of electrocatalytic centers in the palladium decorated graphene. This material can serve as a sensor material for hydrogen at levels from 0.5 to 1% in synthetic air. Pure graphene is poorly sensitive to hydrogen, but incorporation of PdNPs increases its sensitivity by more than an order of magnitude. The effects of hydrogen, nitrogen dioxide and humidity were studied. Sensor regeneration is accelerated in humid air. The sensitivity of the nanocomposite depends on the number of bilayers of graphene-PdNPs.

  13. Electrochemical determination of hydrogen peroxide at glassy carbon electrode modified with palladium nanoparticles

    Directory of Open Access Journals (Sweden)

    Kitte Addisu Shimeles

    2013-01-01

    Full Text Available We report here the modification of glassy carbon electrode (GCE with palladium nanoparticles and palladium film. The response to hydrogen peroxide on the modified electrode was examined using cyclic voltammetry and amperometry (at -0.2 V vs Ag/AgCl reference electrode in the phosphate buffer solution pH 7.4. The palladium film and palladium nanoparticle modified GCE showed a linear response to hydrogen peroxide in the concentration range between 10 μM to 14 mM and 1 μM to 14 mM with detection limit of 6.79 μM and 0.33 μM, respectively.

  14. Nucleation and growth kinetics of palladium nanoparticles on thin ...

    African Journals Online (AJOL)

    Where F is the flux of atoms impinging on the substrate and τ the mean life time of an adatom before desorption. ... temperatures ranging from 573 K to 1073 K and a constant palladium flux 1x1013 atoms cm-2. s-1. For. Ts = 573 K ..... S &Henry. C-R, 2004, Nucleation and growth kinetics of gold nanoparticles on MgO (1 0 0).

  15. Palladium Nanoparticles-Based Fluorescence Resonance Energy Transfer Aptasensor for Highly Sensitive Detection of Aflatoxin M1 in Milk

    National Research Council Canada - National Science Library

    Hui Li; Daibin Yang; Peiwu Li; Qi Zhang; Wen Zhang; Xiaoxia Ding; Jin Mao; Jing Wu

    2017-01-01

    ...) between 5-carboxyfluorescein (FAM) and palladium nanoparticles (PdNPs). PdNPs (33 nm) were synthesized through a seed-mediated growth method and exhibited broad and strong absorption in the whole ultraviolet-visible (UV-Vis) range...

  16. A Range-Based Vehicle Life Cycle Assessment Incorporating Variability in the Environmental Assessment of Different Vehicle Technologies and Fuels

    Directory of Open Access Journals (Sweden)

    Maarten Messagie

    2014-03-01

    Full Text Available How to compare the environmental performance of different vehicle technologies? Vehicles with lower tailpipe emissions are perceived as cleaner. However, does it make sense to look only to tailpipe emissions? Limiting the comparison only to these emissions denies the fact that there are emissions involved during the production of a fuel and this approach gives too much advantage to zero-tailpipe vehicles like battery electric vehicles (BEV and fuel cell electric vehicle (FCEV. Would it be enough to combine fuel production and tailpipe emissions? Especially when comparing the environmental performance of alternative vehicle technologies, the emissions during production of the specific components and their appropriate end-of-life treatment processes should also be taken into account. Therefore, the complete life cycle of the vehicle should be included in order to avoid problem shifting from one life stage to another. In this article, a full life cycle assessment (LCA of petrol, diesel, fuel cell electric (FCEV, compressed natural gas (CNG, liquefied petroleum gas (LPG, hybrid electric, battery electric (BEV, bio-diesel and bio-ethanol vehicles has been performed. The aim of the manuscript is to investigate the impact of the different vehicle technologies on the environment and to develop a range-based modeling system that enables a more robust interpretation of the LCA results for a group of vehicles. Results are shown for climate change, respiratory effects, acidification and mineral extraction damage of the different vehicle technologies. A broad range of results is obtained due to the variability within the car market. It is concluded that it is essential to take into account the influence of all the vehicle parameters on the LCA results.

  17. Colorimetric sensing of malathion using palladium-gold bimetallic nanozyme.

    Science.gov (United States)

    Singh, Shefali; Tripathi, Pranav; Kumar, Nitin; Nara, Seema

    2017-06-15

    In this work, a simple, sensitive and selective label free colorimetric assay using palladium-gold nanorod as nanozyme is reported for malathion detection. Study investigates the peroxidase potential of the nanozyme on colorimetric substrates and explores the effect of selected organophosphates on their enzyme mimetic activity. Palladium-gold nanozyme shows excellent peroxidase mimetic activity with O-phenylenediamine in the presence of hydrogen peroxide. Its Kinetic parameters Km and kcat are better than horseradish peroxidase which makes it a superior enzyme. Nanozyme is stable over a broad temperature range (4-70°C) and shows high peroxidase activity from 2 to 6pH. The peroxidase activity of nanozyme is selectively quenched with increasing concentration of malathion and is the principle of developed assay. Assay has a lowest detection limit of 60ng/ml and shows no cross-reaction with other analogous organophosphates or metal salts. Validation on tap water samples spiked with different concentrations of malathion shows good recovery in the range of 80-106%. Assay also displays good intra and inter-assay precision which lie in the range of 2.7-6.1% and 3.2-5.9% respectively. This study demonstrated the catalytic potential of palladium-gold nanorods, which can be employed as nanozyme for developing highly sensitive detection methods. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Fabrication of Polybenzimidazole/Palladium Nanoparticles Hollow Fiber Membranes for Hydrogen Purification

    KAUST Repository

    Villalobos, Luis Francisco

    2017-09-13

    A novel scheme to fabricate polybenzimidazole (PBI) hollow fiber membranes with a thin skin loaded with fully dispersed palladium nanoparticles is proposed for the first time. Palladium is added to the membrane during the spinning process in the form of ions that coordinate to the imidazole groups of the polymer. This is attractive for membrane production because agglomeration of nanoparticles is minimized and the high-cost metal is incorporated in only the selective layer—where it is required. Pd-containing membranes achieve three orders of magnitude higher H2 permeances and a twofold improvement in H2/CO2 selectivity compared to pure PBI hollow fiber membranes.

  19. Palladium allergy in relation to dentistry

    NARCIS (Netherlands)

    Muris, J.

    2015-01-01

    Palladium is a metal that is used as alloying metal for dental crowns and bridges. This thesis focusses on the possible impact of oral exposure to this metal on the immune system, and allergy in particular. An alternative skin test allergen for diagnosing palladium allergy is introduced: (di)sodium

  20. Simultaneous spectrophotometric determination of mercury and palladium with Thio-Michler's Ketone using partial least squares regression and orthogonal signal correction.

    Science.gov (United States)

    Niazi, Ali; Azizi, Amir; Ramezani, Majid

    2008-12-01

    A simple, novel and sensitive spectrophotometric method was described for simultaneous determination of mercury and palladium. The method is based on the complex formation of mercury and palladium with Thio-Michler's Ketone (TMK) at pH 3.5. All factors affecting on the sensitivity were optimized and the linear dynamic range for determination of mercury and palladium found. The simultaneous determination of mercury and palladium mixtures by using spectrophotometric method is a difficult problem, due to spectral interferences. By multivariate calibration methods such as partial least squares (PLS), it is possible to obtain a model adjusted to the concentration values of the mixtures used in the calibration range. Orthogonal signal correction (OSC) is a preprocessing technique used for removing the information unrelated to the target variables based on constrained principal component analysis. OSC is a suitable preprocessing method for PLS calibration of mixtures without loss of prediction capacity using spectrophotometric method. In this study, the calibration model is based on absorption spectra in the 360-660 nm range for 25 different mixtures of mercury and palladium. Calibration matrices were containing 0.025-1.60 and 0.05-0.50 microg mL(-1) of mercury and palladium, respectively. The RMSEP for mercury and palladium with OSC and without OSC were 0.013, 0.006 and 0.048, 0.030, respectively. This procedure allows the simultaneous determination of mercury and palladium in synthetic and real matrix samples good reliability of the determination.

  1. Palladium on plastic substrates for plasmonic devices.

    Science.gov (United States)

    Zuppella, Paola; Pasqualotto, Elisabetta; Zuccon, Sara; Gerlin, Francesca; Corso, Alain Jody; Scaramuzza, Matteo; De Toni, Alessandro; Paccagnella, Alessandro; Pelizzo, Maria Guglielmina

    2015-01-09

    Innovative chips based on palladium thin films deposited on plastic substrates have been tested in the Kretschmann surface plasmon resonance (SPR) configuration. The new chips combine the advantages of a plastic support that is interesting and commercially appealing and the physical properties of palladium, showing inverted surface plasmon resonance (ISPR). The detection of DNA chains has been selected as the target of the experiment, since it can be applied to several medical early diagnostic tools, such as different biomarkers of cancers or cystic fibrosis. The results are encouraging for the use of palladium in SPR-based sensors of interest for both the advancement of biodevices and the development of hydrogen sensors.

  2. Functionalized 2D-MoS2-Incorporated Polymer Ternary Solar Cells: Role of Nanosheet-Induced Long-Range Ordering of Polymer Chains on Charge Transport.

    Science.gov (United States)

    Ahmad, Razi; Srivastava, Ritu; Yadav, Sushma; Chand, Suresh; Sapra, Sameer

    2017-10-04

    In this paper, we demonstrated the enhancement in power conversion efficiency (PCE) of solar cells based on poly(3-hexylthiophene-2,5-diyl) (P3HT)/[6,6]-phenyl C 71 butyric acid methyl ester (PC 71 BM) by incorporation of functionalized 2D-MoS 2 nanosheets (NSs) as an additional charge-transporting material. The enhancement in PCE of ternary solar cells arises due to the synergic enhancement in exciton dissociation and the improvement in mobility of both electrons and holes through the active layer of the solar cells. The improved hole mobility is attributed to the formation of the long-range ordered nanofibrillar structure of polymer phases and improved crystallinity in the presence of 2D-MoS 2 NSs. The improved electron mobility arises due to the highly conducting 2D network of MoS 2 NSs which provides additional electron transport channels within the active layer. The nanosheet-incorporated ternary blend solar cells exhibit 32% enhancement in PCE relative to the binary blend P3HT/PC 71 BM.

  3. Anionic Palladium(0) and Palladium(II) Ate Complexes.

    Science.gov (United States)

    Kolter, Marlene; Böck, Katharina; Karaghiosoff, Konstantin; Koszinowski, Konrad

    2017-10-16

    Palladium ate complexes are frequently invoked as important intermediates in Heck and cross-coupling reactions, but so far have largely eluded characterization at the molecular level. Here, we use electrospray-ionization mass spectrometry, electrical conductivity measurements, and NMR spectroscopy to show that the electron-poor catalyst [L3 Pd] (L=tris[3,5-bis(trifluoromethyl)phenyl]phosphine) readily reacts with Br(-) ions to afford the anionic, zero-valent ate complex [L3 PdBr](-) . In contrast, more-electron-rich Pd catalysts display lower tendencies toward the formation of ate complexes. Combining [L3 Pd] with LiI and an aryl iodide substrate (ArI) results in the observation of the Pd(II) ate complex [L2 Pd(Ar)I2 ](-) . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Solid phase extraction and spectrophotometric determination of palladium with 2-(2-quinolylazo-5-diethylaminobenzoic acid

    Directory of Open Access Journals (Sweden)

    WEIZU YANG

    2006-07-01

    Full Text Available Asensitive, selective and rapid method for the determination of palladium based on the rapid reaction of palladium(II with 2-(2-quinolylazo-5-diethylaminobenzoic acid (QADEAB and the solid phase extraction of the Pd(II –QADEAB chelate with a reversed phase polymer-based C18 cartridge was developed. In the presence of 0.05 – 0. 5 mol/L of hydrochloric acid solution and cetyl trimethylammonium bromide (CTAB medium, QADEAB reacts with palladium(II to form a violet complex with a mole ratio 1:2 (palladium to QADEAB. The chelate was enriched by solid phase extraction with a reversed phase polymer-based C18 cartridge. An enrichment factor of 200 was obtained by elution of the chelate form the cartridge with the minimal amount of isopentyl alcohol. The molar absorptivity of the chelate in the isopentyl alcohol medium was 1.43 × 105 L mol-1 cm-1 at 628 nm. Beer’s law was obeyed in the range of 0.01 – 1.2 mg/mL. The relative standard deviation for eleven replicate samples at the 0.2 mg/L level was 2.18 %. The attained detection limit amounted to 0.02 mg/L in the original samples. This method was applied to the determination of palladium in environmental samples with good results.

  5. Synthesis and characterization of chitosan and grape polyphenols stabilized palladium nanoparticles and their antibacterial activity.

    Science.gov (United States)

    Amarnath, Kanchana; Kumar, Jayanthi; Reddy, Tejesh; Mahesh, Vakka; Ayyappan, Senniyanallur Rathakrishnan; Nellore, Jayshree

    2012-04-01

    Based on enhanced effectiveness, the new age drugs are nanoparticles of polymers, metals or ceramics, which can combat conditions like cancer and fight human pathogens like bacteria. In this present study we aimed for a green approach to synthesize palladium nanoparticles by reducing palladium chloride salts with nontoxic and biodegradable polymeric chitosan and grape polyphenols and confirmed by FTIR, TEM, SEM and UV-spectroscopy. We also extended our study to show the efficacy of the grape and chitosan impregnated palladium nanoparticles as an antibacterial agent against Escherichia coli. Antibacterial assays were carried out with a representative gram-negative bacterium, E. coli and a gram-positive bacterium, Staphylococcus aureus. Commendable efforts have been made to explore this property using electron microscopy, which has revealed size dependent interaction of palladium nanoparticles conjugates with bacteria by disrupting cell membranes and the leakage of cytoplasm. Therefore, the observed results imply that grape and chitosan-based nano palladium conjugates prepared in our present system are promising candidates for a wide range of biomedical and general applications. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Palladium electrodeposition on polyaniline films

    Energy Technology Data Exchange (ETDEWEB)

    Mourato, A. [Departamento de Quimica e Bioquimica da Faculdade de Ciencias da Universidade de Lisboa, Campo Grande, 1749-016 Lisbon (Portugal); Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern (Switzerland); Correia, J.P. [Departamento de Quimica e Bioquimica da Faculdade de Ciencias da Universidade de Lisboa, Campo Grande, 1749-016 Lisbon (Portugal); Siegenthaler, H. [Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern (Switzerland); Abrantes, L.M. [Departamento de Quimica e Bioquimica da Faculdade de Ciencias da Universidade de Lisboa, Campo Grande, 1749-016 Lisbon (Portugal)], E-mail: luisa.abrantes@fc.ul.pt

    2007-12-01

    The electrochemical nucleation and growth of palladium particles onto polyaniline (PAni) films have been investigated by chronoamperometry and topographic and phase-mode atomic force microscopy (AFM). The films were synthesized under different potentiodynamic conditions in order to obtain polymer layers with comparable electroactivity but distinctly different morphology/porosity. The analysis of the current transients obtained for the initial stages of the Pd deposition indicates a 3D nucleative formation regime. A detailed Pd electrodeposition study onto the polymer matrix, using different deposition times, suggests that a constant number of critical nuclei is formed in the superficial part of the polymer porous matrix in the time scale between ca. 5 and 15 s.

  7. Comparative studies of ONNO-based ligands as ionophores for palladium ion-selective membrane sensors.

    Science.gov (United States)

    Gupta, Vinod K; Goyal, Rajendra N; Sharma, Ram A

    2009-04-30

    Palladium sensors based on two neutral ionophores, N,N'-bis(acetylacetone) cyclohexanediamine (L(1)) and N,N'-bis(o-hydroxyacetophenone)-1,2-cyclohexanediamine (L(2)) for quantification of palladium ions are described. Effect of various plasticizers (o-NPOE, DBP, DEP, DOP, TBP, and CN) and anion excluder, sodium tetra phenyl borate (NaTPB) has been studied. The best performance is obtained with a membrane composition of PVC:o-NPOE:ionophore (L(1)):NaTPB of 150:300:5:5 (%, w/w). The sensor exhibits significantly enhanced selectivity towards palladium ion over the concentration range 1.0 x 10(-8) to 1.0 x 10(-1)M with a lower detection limit of 4.0 x 10(-9)M and a Nernstian compliance (29.1+/-0.3 mV decade(-1) of activity) within pH range 2.0-6.0 and fast response time of 10s. Influence of the membrane composition and possible interfering ions has also been investigated on the response properties of the electrode. Fast and stable response, good reproducibility and long-term stability of the sensor are demonstrated. The sensor has been found to work satisfactorily in partially non-aqueous media up to 20% (v/v) content of methanol, ethanol and acetonitrile and could be used for a period of 4 months. Selectivity coefficients determined with fixed interference method (FIM) indicate high selectivity for palladium. The proposed electrode shows fairly good discrimination of palladium from other cations. The application of prepared sensor has been demonstrated in determination of palladium ions in spiked water sample.

  8. Superlattices of platinum and palladium nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    MARTIN,JAMES E.; WILCOXON,JESS P.; ODINEK,JUDY G.; PROVENCIO,PAULA P.

    2000-04-06

    The authors have used a nonionic inverse micelle synthesis technique to form nanoclusters of platinum and palladium. These nanoclusters can be rendered hydrophobic or hydrophilic by the appropriate choice of capping ligand. Unlike Au nanoclusters, Pt nanoclusters show great stability with thiol ligands in aqueous media. Alkane thiols, with alkane chains ranging from C{sub 6} to C{sub 18} were used as hydrophobic ligands, and with some of these they were able to form 2-D and/or 3-D superlattices of Pt nanoclusters as small as 2.7 nm in diameter. Image processing techniques were developed to reliably extract from transmission electron micrographs (TEMs) the particle size distribution, and information about the superlattice domains and their boundaries. The latter permits one to compute the intradomain vector pair correlation function of the particle centers, from which they can accurately determine the lattice spacing and the coherent domain size. From these data the gap between the particles in the coherent domains can be determined as a function of the thiol chain length. It is found that as the thiol chain length increases, the gaps between particles within superlattice domains increases, but more slowly than one might expect, possibly indicating thiol chain interdigitation.

  9. Synthesis of 2-aminoBODIPYs by palladium catalysed amination.

    Science.gov (United States)

    Alnoman, Rua B; Stachelek, Patrycja; Knight, Julian G; Harriman, Anthony; Waddell, Paul G

    2017-09-20

    Palladium catalysed coupling of the 2-iodoBODIPY 3 with a range of anilines and a primary alkylamine succeeds in generating the corresponding 2-aminoBODIPYs. These 2-aminoBODIPY derivatives are non-emissive and quantum chemical calculations and electrochemistry are consistent with charge transfer from the amine substituent. Attenuation of this charge transfer pathway by conversion of the 1,2-phenylenediamine derivative 9 into the corresponding benzimidazolone 10 restores the fluorescence and has been used as the basis for a fluorescence sensor for phosgene.

  10. Wavelength response of a surface plasmon resonance palladium-coated optical fiber sensor for hydrogen detection

    NARCIS (Netherlands)

    Perrotton, C.; Slaman, M.; Javahiraly, N.; Schreuders, H.; Dam, B.; Meyrueis, P.

    2011-01-01

    An optical fiber using palladium as sensitive layer is characterized in the range of 450 to 900 nm. The sensitive layer is deposited on the outside of a multimode fiber, after removing the optical cladding. The sensor is based on a measurement technique that uses the surface plasmon resonance

  11. Ligand-free palladium catalysed Heck reaction of methyl 2-acetamido acrylate and aryl bromides as key step in the synthesis of enantiopure substituted phenylalanines

    NARCIS (Netherlands)

    Willans, Charlotte E.; Mulders, Jan M.C.A.; Vries, Johannes G. de; Vries, André H.M. de

    2003-01-01

    A range of substituted aryl bromides were coupled with methyl 2-acetamido acrylate using ligand-free palladium catalysis. Subsequently asymmetric hydrogenation with Rh/MonoPhos yielded substituted phenylalanines in high enantioselectivities (e.e. 92-99%).

  12. Passive fit of frameworks in titanium and palladium-silver alloy submitted the laser welding.

    Science.gov (United States)

    de Sousa, S A; de Arruda Nobilo, M A; Henriques, G E P; Mesquita, M F

    2008-02-01

    This study evaluated the precision of fit of implant frameworks cast in titanium (cp Ti) and palladium-silver alloy (Pd-Ag), made by the one-piece cast and laser welding techniques. From a metal matrix with five implants, 20 master casts were obtained, to which replicas of implants were incorporated. On these masters 10 frameworks were made for each type of material (cp Ti and Pd-Ag alloy). Half of these were made by the one-piece cast technique and the other half by the laser welding technique. The implant/prosthesis interface was analysed and measured in the vestibular and lingual regions of the central and distal implants with the help of a measuring microscope. The results indicated that in the central cylinders, the Tukey test (Pwelded frameworks (34.73 microm) and those one-piece cast frameworks (151.39 microm), and as regards materials, the palladium-silver alloy (66.30 microm) showed better results than the titanium (119.83 microm). In the distal cylinders there was no significant difference between the frameworks cast in titanium and palladium-silver by the one-piece technique. However, after laser welding, there was a significant difference for the frameworks cast in titanium (31.37 microm) and palladium-silver (106.59 microm).

  13. Quantitative in-situ scanning electron microscope pull-out experiments and molecular dynamics simulations of carbon nanotubes embedded in palladium

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, S., E-mail: steffen.hartmann@etit.tu-chemnitz.de; Blaudeck, T.; Hermann, S.; Wunderle, B. [Technische Universität Chemnitz, Reichenhainer Str. 70, 09126 Chemnitz (Germany); Hölck, O. [Technische Universität Chemnitz, Reichenhainer Str. 70, 09126 Chemnitz (Germany); Fraunhofer IZM Berlin, Gustav-Meyer-Allee 25, 13355 Berlin (Germany); Schulz, S. E.; Gessner, T. [Technische Universität Chemnitz, Reichenhainer Str. 70, 09126 Chemnitz (Germany); Fraunhofer ENAS Chemnitz, Technologie-Campus 3, 09126 Chemnitz (Germany)

    2014-04-14

    In this paper, we present our results of experimental and numerical pull-out tests on carbon nanotubes (CNTs) embedded in palladium. We prepared simple specimens by employing standard silicon wafers, physical vapor deposition of palladium and deposition of CNTs with a simple drop coating technique. An AFM cantilever with known stiffness connected to a nanomanipulation system was utilized inside a scanning electron microscope (SEM) as a force sensor to determine forces acting on a CNT during the pull-out process. SEM-images of the cantilever attached to a CNT have been evaluated for subsequent displacement steps with greyscale correlation to determine the cantilever deflection. We compare the experimentally obtained pull-out forces with values of numerical investigations by means of molecular dynamics and give interpretations for deviations according to material impurities or defects and their influence on the pull-out data. We find a very good agreement of force data from simulation and experiment, which is 17 nN and in the range of 10–61 nN, respectively. Our findings contribute to the ongoing research of the mechanical characterization of CNT-metal interfaces. This is of significant interest for the design of future mechanical sensors utilizing the intrinsic piezoresistive effect of CNTs or other future devices incorporating CNT-metal interfaces.

  14. Silver-Palladium Surfaces Inhibit Biofilm Formation

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Schroll, Casper; Hilbert, Lisbeth Rischel

    2009-01-01

    Undesired biofilm formation is a major concern in many areas. In the present study, we investigated biofilm-inhibiting properties of a silver-palladium surface that kills bacteria by generating microelectric fields and electrochemical redox processes. For evaluation of the biofilm inhibition...... efficacy and study of the biofilm inhibition mechanism, the silver-sensitive Escherichia coli J53 and the silver-resistant E. coli J53[pMG101] strains were used as model organisms, and batch and flow chamber setups were used as model systems. In the case of the silver-sensitive strain, the silver......-palladium surfaces killed the bacteria and prevented biofilm formation under conditions of low or high bacterial load. In the case of the silver-resistant strain, the silver-palladium surfaces killed surface-associated bacteria and prevented biofilm formation under conditions of low bacterial load, whereas under...

  15. Palladium on Plastic Substrates for Plasmonic Devices

    Directory of Open Access Journals (Sweden)

    Paola Zuppella

    2015-01-01

    Full Text Available Innovative chips based on palladium thin films deposited on plastic substrates have been tested in the Kretschmann surface plasmon resonance (SPR configuration. The new chips combine the advantages of a plastic support that is interesting and commercially appealing and the physical properties of palladium, showing inverted surface plasmon resonance (ISPR. The detection of DNA chains has been selected as the target of the experiment, since it can be applied to several medical early diagnostic tools, such as different biomarkers of cancers or cystic fibrosis. The results are encouraging for the use of palladium in SPR-based sensors of interest for both the advancement of biodevices and the development of hydrogen sensors.

  16. Chiral imprinting of palladium with cinchona alkaloids

    NARCIS (Netherlands)

    Durán Páchon, L.; Yosef, I.; Markus, T.Z.; Naaman, R.; Avnir, D.; Rothenberg, G.

    2009-01-01

    In the search for new materials and concepts in materials science, metallo-organic hybrids are attractive candidates; they can combine the rich diversity of organic molecules with the advantages of metals. Transition metals such as palladium are widely applied in catalysis, and small organic

  17. Palladium complexes of pyrrole-2-aldehyde thiosemicarbazone ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 126; Issue 5. Palladium complexes ... Bhattacharya. Special issue on Chemical Crystallography Volume 126 Issue 5 September 2014 pp 1547-1555 ... Bhattacharya1. Department of Chemistry, Inorganic Chemistry Section, Jadavpur University, Kolkata 700 032, India ...

  18. Sodium tetrachloropalladate for diagnosing palladium sensitization

    NARCIS (Netherlands)

    Muris, J.; Kleverlaan, C.J.; Rustemeyer, T.; von Blomberg, M.E.; van Hoogstraten, I.M.W.; Feilzer, A.J.; Scheper, R.J.

    2012-01-01

    Background. Exposure to palladium (Pd) may lead to clinical allergic reactions. With frequent nickel (Ni) exposure and cross-reactivity between Ni and Pd at the T cell recognition level, positive Pd reactions on patch testing are surprisingly uncommon. PdCl2 is often used for epicutaneous patch

  19. Palladium catalysed asymmetric alkylation of benzophenone Schiff ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 123; Issue 4. Palladium catalysed asymmetric alkylation of benzophenone Schiff base glycine esters in ionic liquids. Dae Hyun Kim Jin Kyu Im Dae Won Kim Minserk Cheong Hoon Sik Kim Deb Kumar Mukherjee. Volume 123 Issue 4 July 2011 pp 467-476 ...

  20. Palladium-Catalyzed Asymmetric Quaternary Stereocenter Formation

    NARCIS (Netherlands)

    Gottumukkala, Aditya L.; Matcha, Kiran; Lutz, Martin; de Vries, Johannes G.; Minnaard, Adriaan J.

    2012-01-01

    An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of beta,beta-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl2, PhBOX, and AgSbF6, and

  1. Palladium-catalyzed asymmetric quaternary stereocenter formation

    NARCIS (Netherlands)

    Gottumukkala, A.L.; Matcha, K.; Lutz, M.|info:eu-repo/dai/nl/304828971; de Vries, J.G.; Minnaard, A.J.

    2012-01-01

    An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of β,β-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl2, PhBOX, and AgSbF6, and provides

  2. Nucleation and growth of copper selective-area atomic layer deposition on palladium nanostructures

    Science.gov (United States)

    Qi, J.; Zimmerman, D. T.; Weisel, G. J.; Willis, B. G.

    2017-10-01

    The nucleation and growth of copper atomic layer deposition (ALD) on palladium have been investigated for applications in nanoscale devices. Palladium nanostructures were fabricated by electron beam lithography and range in size from 250 nm to 5 μm, prepared on oxidized silicon wafers. Copper ALD using Cu(thd)2(s) and H2(g) as reactants was carried out to selectively deposit copper on palladium seeded regions to the exclusion of surrounding oxide surfaces. Nuclei sizes and densities have been quantified by scanning electron microscopy for different growth conditions. It is found that growth occurs via island growth at temperatures of 150-190 °C and alloy growth at temperatures above 210 °C. In the lower temperature window, nucleation density increases with decreasing temperature, reaching a maximum of 4.8 ± 0.2 × 109/cm2 at 150 °C, but growth is too slow for significant deposition at the lowest temperatures. At higher temperatures, individual nuclei cannot be quantified due to extensive mixing of copper and palladium layers. For the lower temperatures where nuclei can be quantified, rates of nucleation and growth are enhanced at high H2 partial pressures. At the smallest length scales, conformality of the deposited over-layers is limited by a finite nuclei density and evolving grain structure that cause distortion of the original nanostructure shape during growth.

  3. Preparation of palladium impregnated alumina adsorbents: Thermal and neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Sumanta; Gupta, N.K.; Roy, S.P.; Dash, S.; Kumar, A.; Bamankar, Y.R.; Rao, T.V. Vittal [Product Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kumar, N. [Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Naik, Y., E-mail: ynaik@barc.gov.in [Product Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2016-02-10

    Highlights: • Pd/Al{sub 2}O{sub 3} composite microspheres particles with high surface area were prepared sol–gel process. • Scanning electron microscopy (SEM) studies on silver coated particle. • Content of the palladium was determined using Neutron Activation Analysis (NAA). • Decomposition study has been done by quadrupole mass analyser. - Abstract: Pd/Al{sub 2}O{sub 3} composite microspheres particles with high surface area were prepared sol–gel process. The decomposition of dried gel-particles was studied by TGA/DTA and FT-IR technique. TGA studies indicated that formation of palladium is marked by a broad exothermic peak with a loss of water and oxidation of trapped HMTA/Urea nitrate mixture. The main decomposition reaction took place in the temperature range of 660–1250 K in helium and relatively lower temperature of 400 K to 1250 K in oxygen. Optical microscopy indicated that the distribution of palladium is uniform. SEM studies on silver coated particle indicated that there was surface erosion of some gel spheres while in few of them micro cracks were seen at high resolution. Content of the palladium was determined using Neutron Activation Analysis (NAA). Decomposition at various temperatures was studied using Residual gas analyser and decomposition species were identified using quadrupole mass analyser.

  4. Liquid-liquid extraction of palladium(II) from nitric acid by bis(2-ethylhexyl) sulphoxide

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, J.P. (Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Bombay 400085 (India)); Singh, R.K.; Sawant, S.R.; Varadarajan, N. (Power Reactor Fuel Reprocessing Plant, Bhabha Atomic Research Centre, Trombay, Bombay 400085 (India))

    1993-04-15

    The extraction of palladium(II) nitrate by bis(2-ethylhexyl) sulphoxide (BESO) was evaluated over a wide range of acidity, and BESO was shown to have a strong extraction ability toward this thiophilic 'soft' metal. Essentially quantitative extraction of trace and macro amounts of palladium is easily accomplished from about 8 M HNO 8 M HNO[sub 3] down to pH 2 solutions by 0.2 M BESO into toluene. Optimum conditions such as aqueous phase acidity, solvent, period of equilibration, aqueous to organic phase ratios, reagent concentration and strippant were established for the selective and reversible extraction and separation of palladium. Slope analyses applied to Pd(II) distribution experiments from nitrate solutions showed a predominant formation of the solvated organic phase complex Pd(NO[sub 3])[sub 2].2BESO. Recovery of the extractant from loaded palladium is easily accomplished by using sodium thiosulphate or a mixture of 2 M sodium carbonate+0.5 M ammonia solution. The extracted complex was characterized by elemental analysis and IR and UV-visible spectrometry, and its composition was confirmed to be Pd(NO[sub 3])[sub 2].2BESO

  5. Oxygen Activated, Palladium Nanoparticle Catalyzed, Ultrafast Cross-Coupling of Organolithium Reagents.

    Science.gov (United States)

    Heijnen, Dorus; Tosi, Filippo; Vila, Carlos; Stuart, Marc C A; Elsinga, Philip H; Szymanski, Wiktor; Feringa, Ben L

    2017-03-13

    The discovery of an ultrafast cross-coupling of alkyl- and aryllithium reagents with a range of aryl bromides is presented. The essential role of molecular oxygen to form the active palladium catalyst was established; palladium nanoparticles that are highly active in cross-coupling reactions with reaction times ranging from 5 s to 5 min are thus generated in situ. High selectivities were observed for a range of heterocycles and functional groups as well as for an expanded scope of organolithium reagents. The applicability of this method was showcased by the synthesis of the [ 11 C]-labeled PET tracer celecoxib. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. The Use of Palladium on Magnetic Support as Catalyst for Suzuki–Miyaura Cross-Coupling Reactions

    Directory of Open Access Journals (Sweden)

    Magne O. Sydnes

    2017-01-01

    Full Text Available The development of new solid supports for palladium has received a lot of interest lately. These catalysts have been tested in a range of cross-coupling reactions, such as Suzuki–Miyaura, Mizoroki-Heck, and Sonogashira cross-coupling reactions, with good outcomes. Attaching the catalyst to a solid support simplifies the operations required in order to isolate and recycle the catalyst after a reaction has completed. Palladium on solid supports made of magnetic materials is particularly interesting since such catalysts can be removed very simply by utilizing an external magnet, which withholds the catalyst in the reaction vessel. This review will showcase some of the latest magnetic solid supports for palladium and highlight these catalysts’ performance in Suzuki–Miyaura cross-coupling reactions.

  7. QuadraPure-Supported Palladium Nanocatalysts for Microwave-Promoted Suzuki Cross-Coupling Reaction under Aerobic Condition

    Directory of Open Access Journals (Sweden)

    Kin Hong Liew

    2014-01-01

    Full Text Available Cross-linked resin-captured palladium (XL-QPPd was readily prepared by simple physical adsorption onto the high loading QuadraPure macroporous resin and a subsequent reduction process. To enhance the mechanical stability, entrapped palladium nanocatalysts were cross-linked with succinyl chloride. Both transmission electron microscopy images and X-ray diffraction analysis revealed that the palladium nanoparticles were well dispersed with diameters ranging in 4–10 nm. The catalyst performed good catalytic activity in microwave-promoted Suzuki cross-coupling reactions in water under aerobic condition with mild condition by using various aryl halides and phenylboronic acid. In addition, the catalyst showed an excellent recyclability without significant loss of catalytic activity.

  8. Functionalized Palladium Nanoparticles for Hydrogen Peroxide Biosensor

    Directory of Open Access Journals (Sweden)

    H. Baccar

    2011-01-01

    Full Text Available We present a comparison between two biosensors for hydrogen peroxide (H2O2 detection. The first biosensor was developed by the immobilization of Horseradish Peroxidase (HRP enzyme on thiol-modified gold electrode. The second biosensor was developed by the immobilization of cysteamine functionalizing palladium nanoparticles on modified gold surface. The amino groups can be activated with glutaraldehyde for horseradish peroxidase immobilization. The detection of hydrogen peroxide was successfully observed in PBS for both biosensors using the cyclic voltammetry and the chronoamperometry techniques. The results show that the limit detection depends on the large surface-to-volume ratio attained with palladium nanoparticles. The second biosensor presents a better detection limit of 7.5 μM in comparison with the first one which is equal to 75 μM.

  9. Palladium-catalysed ortho arylation of acetanilides

    Indian Academy of Sciences (India)

    The palladium-catalysed direct arylation of acetanilides by using C-H activation methodology has been demonstrated. Several acetanilides were coupled with aryl iodides in the presence of 10 mol% of Pd(OAc)2, 1.0 equiv of Cu(OTf)2, and 0.6 equiv of Ag2O to afford the corresponding products in moderate to excellent ...

  10. Palladium-Catalyzed, Enantioselective Heine Reaction.

    Science.gov (United States)

    Punk, Molly; Merkley, Charlotte; Kennedy, Katlyn; Morgan, Jeremy B

    2016-07-01

    Aziridines are important synthetic intermediates for the generation of nitrogen-containing molecules. N-Acylaziridines undergo rearrangement by ring expansion to produce oxazolines, a process known as the Heine reaction. The first catalytic, enantioselective Heine reaction is reported for meso-N-acylaziridines where a palladium(II)-diphosphine complex is employed. The highly enantioenriched oxazoline products are valuable organic synthons and potential ligands for transition-metal catalysis.

  11. Palladium-catalysed ortho arylation of acetanilides

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The palladium-catalysed direct arylation of acetanilides by using C–H activation methodo- logy has been demonstrated. Several acetanilides were coupled with aryl iodides in the presence of. 10 mol% of Pd(OAc)2, 1⋅0 equiv of Cu(OTf)2, and 0⋅6 equiv of Ag2O to afford the corresponding products in moderate to ...

  12. An ultrasensitive electrochemical genosensor for Brucella based on palladium nanoparticles.

    Science.gov (United States)

    Rahi, A; Sattarahmady, N; Heli, H

    2016-10-01

    Palladium nanoparticles were potentiostatically electrodeposited on a gold surface at a highly negative potential. The nanostructure, as a transducer, was utilized to immobilize a Brucella-specific probe and the process of immobilization and hybridization was detected by electrochemical methods. The proposed method for detection of the complementary sequence and a non-complementary sequence was applied. The fabricated genosensor was evaluated for the assay of the bacteria in the cultured and human samples with and without PCR. The genosensor could detect the complementary sequence with a sensitivity of 0.02 μA dm(3) mol(-1), a linear concentration range of 1.0 × 10(-12) to 1.0 × 10(-19) mol dm(-3), and a detection limit of 2.7 × 10(-20) mol dm(-3). Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Superparamagnetic bimetallic iron-palladium nanoalloy: synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Nazir, Rabia; Mazhar, Muhammad [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Akhtar, M Javed; Nadeem, M; Siddique, Muhammad [Physics Division, PINSTECH, PO Nilore, Islamabad 44000 (Pakistan); Shah, M Raza [HEJ Research Institute of Chemistry, University of Karachi, Karachi 75270 (Pakistan); Khan, Nawazish A [Material Science Laboratory, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Mehmood, Mazhar [National Centre for Nanotechnology, PIEAS, Islamabad 45650 (Pakistan); Butt, N M [Pakistan Science Foundation, Islamabad 44000 (Pakistan)], E-mail: mazhar42pk@yahoo.com

    2008-05-07

    Iron-palladium nanoalloy in the particle size range of 15-30 nm is synthesized by the relatively low temperature thermal decomposition of coprecipitated [Fe(Bipy){sub 3}]Cl{sub 2} and [Pd(Bipy){sub 3}]Cl{sub 2} in an inert ambient of dry argon gas. The silvery black Fe-Pd alloy nanoparticles are air-stable and have been characterized by EDX-RF, XRD, AFM, TEM, magnetometry, {sup 57}Fe Moessbauer and impedance spectroscopy. This Fe-Pd nanoalloy is in single phase and contains iron sites having up to 11 nearest-neighboring atoms. It is superparamagnetic in nature with high magnetic susceptibility, low coercivity and hyperfine field.

  14. The Net Adsorption of Hydrogen on Palladium Nanoparticles

    Science.gov (United States)

    Sahu, Debjyoti; Mishra, Prashant; Das, Nitun; Verma, Anil; Gumma, Sasidhar

    2014-01-01

    In this paper, we report the synthesis of polymer coated palladium (Pd) nanoparticles through a single stage reduction of Pd2+ ions by ethylene glycol. Polyvinyl pyrrolidone (PVP, MW 25,000) is used as a stabilizer. Self-assembled Pd nanoparticles (10-40 nm) were used in hydrogen adsorption studies. Gravimetric adsorption measurements were carried out in a pressure range of 0-26 bar at 293, 324, 364 and 392 K. Saturation for all isotherms was obtained within a few bars of pressure at all temperatures. Maximum hydrogen storage capacity observed was 0.58 wt.% at 324 K and 20 bar. Net adsorption calculations indicated that required tank volume (for storing a particular amount of hydrogen) can be significantly reduced by using a tank filled with Pd nanoparticle.

  15. Extracellular Palladium Nanoparticle Production using Geobacter sulfurreducens

    KAUST Repository

    Yates, Matthew D.

    2013-09-03

    Sustainable methods are needed to recycle precious metals and synthesize catalytic nanoparticles. Palladium nanoparticles can be produced via microbial reduction of soluble Pd(II) to Pd(0), but in previous tests using dissimilatory metal reducing bacteria (DMRB), the nanoparticles were closely associated with the cells, occupying potential reductive sites and eliminating the potential for cell reuse. The DMRB Geobacter sulfurreducens was shown here to reduce soluble Pd(II) to Pd(0) nanoparticles primarily outside the cell, reducing the toxicity of metal ions, and allowing nanoparticle recovery without cell destruction that has previously been observed using other microorganisms. Cultures reduced 50 ± 3 mg/L Pd(II) with 1% hydrogen gas (v/v headspace) in 6 h incubation tests [100 mg/L Pd(II) initially], compared to 8 ± 3 mg/L (10 mM acetate) without H2. Acetate was ineffective as an electron donor for palladium removal in the presence or absence of fumarate as an electron acceptor. TEM imaging verified that Pd(0) nanoparticles were predominantly in the EPS surrounding cells in H2-fed cultures, with only a small number of particles visible inside the cell. Separation of the cells and EPS by centrifugation allowed reuse of the cell suspensions and effective nanoparticle recovery. These results demonstrate effective palladium recovery and nanoparticle production using G. sulfurreducens cell suspensions and renewable substrates such as H2 gas. © 2013 American Chemical Society.

  16. Palladium(II)-catalyzed regioselective arylation of naphthylamides with aryl iodides utilizing a quinolinamide bidentate system.

    Science.gov (United States)

    Huang, Lehao; Li, Qian; Wang, Chen; Qi, Chenze

    2013-04-05

    A palladium(II)-catalyzed quinolinamide-directed 8-arylation of 1-naphthylamides with aryl iodides is reported. The bidentate directing group (quinolinamide) proved to be crucial for a highly regioselective transformation. In addition, the amide directing group can be easily hydrolyzed under basic conditions to offer a range of 8-aryl-1-naphthylamine derivatives. The theoretical calculations suggest that the C-H arylation reaction proceeds through a sequential C-H activation/oxidative addition pathway.

  17. Thermodynamics of the hybrid interaction of hydrogen with palladium nanoparticles

    NARCIS (Netherlands)

    Griessen, R.P.; Strohfeldt, N.; Giessen, H.

    2015-01-01

    Palladium-hydrogen is a prototypical metal-hydrogen system. It is therefore not at all surprising that a lot of attention has been devoted to the absorption and desorption of hydrogen in nanosized palladium particles. Several seminal articles on the interaction of H with Pd nanocubes and

  18. Extending unsupported metal-only Lewis pairs to palladium.

    Science.gov (United States)

    Bauer, Jürgen; Braunschweig, Holger; Damme, Alexander; Gruss, Katrin; Radacki, Krzysztof

    2011-12-28

    Synthesis of the first unsupported palladium-to-main group metal Lewis pair is reported, including a new synthesis for heteroleptic mono(NHC)-monophosphine palladium(0) complexes. All compounds were analysed by single crystal X-ray diffraction, multinuclear NMR spectroscopy and density functional theory calculations. This journal is © The Royal Society of Chemistry 2011

  19. Toward Efficient Palladium-Catalyzed Allylic C-H Alkylation

    DEFF Research Database (Denmark)

    Jensen, Thomas; Fristrup, Peter

    2009-01-01

    Recent breakthroughs have proved that direct palladium (II)-catalyzed allylic C-H alkylation can be achieved. This new procedure shows that the inherent requirement for a leaving group in the Tsuji-Trost palladium-catalyzed allylic alkylation can be lifted. These initial reports hold great promise...

  20. Palladium(0)-catalyzed single and double isonitrile insertion: a facile synthesis of benzofurans, indoles, and isatins.

    Science.gov (United States)

    Senadi, Gopal Chandru; Hu, Wan-Ping; Boominathan, Siva Senthil Kumar; Wang, Jeh-Jeng

    2015-01-12

    A palladium(0)-catalyzed cascade process consisting of isonitrile insertion and α-Csp(3)-H cross-coupling can be achieved for the synthesis of benzofurans and indoles. The construction of isatins by a Pd-catalyzed cascade reaction incorporating double isonitrile insertion, amination, and hydrolysis has also been achieved. The key features of this work include diverse heterocycle synthesis, phosphine-ligand-free reaction conditions, a one-pot procedure, simple and commercially available starting materials, broad functional-group compatibility, and moderate to good reaction yields. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Highly ordered palladium nanodots and nanowires from switchable block copolymer thin films

    Science.gov (United States)

    Bhoje Gowd, E.; Nandan, Bhanu; Vyas, Mukesh Kumar; Bigall, Nadja C.; Eychmüller, Alexander; Schlörb, Heike; Stamm, Manfred

    2009-10-01

    We demonstrate a new approach to fabricate highly ordered arrays of nanoscopic palladium dots and wires using switchable block copolymer thin films. The surface-reconstructed block copolymer templates were directly deposited with palladium nanoparticles from a simple aqueous solution. The preferential interaction of the nanoparticles with one of the blocks is mainly responsible for the lateral arrangement of the nanoparticles inside the pores of the templates in addition to the capillary forces. A subsequent stabilization by UV-irradiation followed by pyrolysis in air at 450 °C removes the polymer to produce highly ordered metallic nanostructures. We extended this approach to micellar films to obtain metallic nanostructures. This method is highly versatile as the procedure used here is simple, eco-friendly and provides a simple approach to fabricate a broad range of nanoscaled architectures with tunable lateral spacing, and can be extended to systems with even smaller dimensions.

  2. Microbial engineering of nano-heterostructures; biological synthesis of a magnetically-recoverable palladium nanocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Coker, V. S.; Bennett, J. A.; Telling, N.; Charnock, J. M.; van der Laan, G.; Pattrick, R. A. D.; Pearce, C. I; Cutting, R. S.; Shannon, I. J.; Wood, J.; Arenholz, E.; Vaughan, D. J.; Lloyd, J. R.

    2009-12-01

    Precious metals supported on ferrimagnetic particles form a diverse range of catalysts. Here we show a novel biotechnological route for the synthesis of a heterogeneous catalyst consisting of reactive palladium nanoparticles arrayed on a biomagnetite support. The magnetic support was synthesized at ambient temperature by the Fe(III)-reducing bacterium, Geobacter sulfurreducens, and facilitated ease of recovery of the catalyst with superior performance due to reduced agglomeration. Arrays of palladium nanoparticles were deposited on the nanomagnetite using a simple one-step method without the need to modify the biomineral surface most likely due to an organic coating priming the surface for Pd adsorption. A combination of EXAFS and XPS showed the particles to be predominantly metallic in nature. The Pd{sup 0}-biomagnetite was tested for catalytic activity in the Heck Reaction coupling iodobenzene to ethyl acrylate or styrene and near complete conversion to ethyl cinnamate or stilbene was achieved within 90 and 180 min, respectively.

  3. Nonenzymatic glucose sensing based on deposited palladium nanoparticles on epoxy-silver electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Gutes, Albert, E-mail: agutes@gmail.com [Department of Chemical and Biomolecular Engineering, University of California at Berkeley, Berkeley, CA 94720 (United States); Carraro, Carlo; Maboudian, Roya [Department of Chemical and Biomolecular Engineering, University of California at Berkeley, Berkeley, CA 94720 (United States)

    2011-07-01

    Highlights: > New nonenzymatic glucose sensor material. > Modified epoxy-silver electrodes with palladium nanoparticles. > Simple electroless surface modification. > Wide linear response range. > Easy implementation. - Abstract: A new approach for nonenzymatic glucose sensing, based on a simple modification of epoxy-silver surfaces deposited on the tip of commercial copper electric wires, is presented. Palladium was galvanically displaced on the surface of the epoxy-silver surface in order to obtain metal nanoparticles that act as catalyst for the direct oxidation of glucose. Scanning electron microscopy revealed the formation of the metal nanoparticles. X-ray photoelectron spectroscopy confirmed the metallic nature of the formed nanostructures on the surface. Electrochemical characterization and calibration of the palladium-modified epoxy-silver electrode is reported, obtaining a linear range of 1-20 mM for the detection of glucose with low interference of ascorbic acid and uric acid. A simple 3-step coulometry was used as the detection technique. The developed sensing material is believed to be a great candidate for integration in small devices for clinical essays, due to the simplicity and cost effectiveness of the presented approach, compared to the state-of-the-art devices reported recently in the literature. Simplicity in the coulometry determinations makes these Pd-modified epoxy-silver sensors a good candidate for easy glucose determinations.

  4. Density functional theory metadynamics of silver, caesium and palladium diffusion at β-SiC grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Rabone, Jeremy, E-mail: jeremy.rabone@ec.europa.eu [European Commission, Joint Research Centre, Institute for Transuranium Elements, D-76125 Karlsruhe (Germany); López-Honorato, Eddie [Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV), Unidad Saltillo, Industria Metalúrgica 1062, Parque Industrial, Ramos Arizpe 25900, Coahuila (Mexico)

    2015-03-15

    Highlights: • DFT metadynamics of diffusion of Pd, Ag and Cs on grain boundaries in β-SiC. • The calculated diffusion rates for Pd and Ag tally with experimental release rates. • A mechanism of release other than grain boundary diffusion seems likely for Cs. - Abstract: The use of silicon carbide in coated nuclear fuel particles relies on this materials impermeability towards fission products under normal operating conditions. Determining the underlying factors that control the rate at which radionuclides such as Silver-110m and Caesium-137 can cross the silicon carbide barrier layers, and at which fission products such as palladium could compromise or otherwise alter the nature of this layer, are of paramount importance for the safety of this fuel. To this end, DFT-based metadynamics simulations are applied to the atomic diffusion of silver, caesium and palladium along a Σ5 grain boundary and to palladium along a carbon-rich Σ3 grain boundary in cubic silicon carbide at 1500 K. For silver, the calculated diffusion coefficients lie in a similar range (7.04 × 10{sup −19}–3.69 × 10{sup −17} m{sup 2} s{sup −1}) as determined experimentally. For caesium, the calculated diffusion rates are very much slower (3.91 × 10{sup −23}–2.15 × 10{sup −21} m{sup 2} s{sup −1}) than found experimentally, suggesting a different mechanism to the simulation. Conversely, the calculated atomic diffusion of palladium is very much faster (7.96 × 10{sup −11}–7.26 × 10{sup −9} m{sup 2} s{sup −1}) than the observed penetration rate of palladium nodules. This points to the slow dissolution and rapid regrowth of palladium nodules as a possible ingress mechanism in addition to the previously suggested migration of entire nodules along grain boundaries. The diffusion rate of palladium along the Σ3 grain boundary was calculated to be slightly slower (2.38 × 10{sup −11}–8.24 × 10{sup −10} m{sup 2} s{sup −1}) than along the Σ5 grain boundary. Rather

  5. Palladium-defect complexes in diamond and silicon carbide

    Energy Technology Data Exchange (ETDEWEB)

    Abiona, A. A., E-mail: adurafimihan.abiona@gmail.com; Kemp, W.; Timmers, H. [University of New South Wales, Canberra, School of Physical, Environmental and Mathematical Sciences (Australia); Bharuth-Ram, K. [Durban University of Technology, Physics Department (South Africa)

    2015-04-15

    Time Differential Perturbed Angular Correlations (TDPAC) studies, supported by Density Functional Theory (DFT) modelling, have shown that palladium atoms in silicon and germanium pair with vacancies. Building on these results, here we present DFT predictions and some tentative TDPAC results on palladium-defect complexes and site locations of palladium impurities in diamond and silicon carbide. For both diamond and silicon carbide, the DFT calculations predict that a split-vacancy V-PdBI-V complex is favoured, with the palladium atom on a bond-centred interstitial site having a nearest-neighbour semi-vacancy on either side. Consistent with experimental results, this configuration is also assigned to palladium complexes in silicon and germanium. For silicon carbide, the DFT modelling predicts furthermore that a palladium atom in replacing a carbon atom moves to a bond-centred interstitial site and pairs with a silicon vacancy to form a complex that is more stable than that of a palladium atom which replaces a silicon atom and then moves to a bond-centred interstitial site pairings with a carbon vacancy. These two competing alternatives differ by 8.94 eV. The favourable pairing with a silicon vacancy is also supported independently by TRIM Monte Carlo calculations, which predict that more silicon vacancies than carbon vacancies are created during heavy ion. implantation.

  6. Microbial engineering of nanoheterostructures: biological synthesis of a magnetically recoverable palladium nanocatalyst.

    Science.gov (United States)

    Coker, Victoria S; Bennett, James A; Telling, Neil D; Henkel, Torsten; Charnock, John M; van der Laan, Gerrit; Pattrick, Richard A D; Pearce, Carolyn I; Cutting, Richard S; Shannon, Ian J; Wood, Joe; Arenholz, Elke; Lyon, Ian C; Lloyd, Jonathan R

    2010-05-25

    Precious metals supported on ferrimagnetic particles have a diverse range of uses in catalysis. However, fabrication using synthetic methods results in potentially high environmental and economic costs. Here we show a novel biotechnological route for the synthesis of a heterogeneous catalyst consisting of reactive palladium nanoparticles arrayed on a nanoscale biomagnetite support. The magnetic support was synthesized at ambient temperature by the Fe(III)-reducing bacterium, Geobacter sulfurreducens , and facilitated ease of recovery of the catalyst with superior performance due to reduced agglomeration (versus conventional colloidal Pd nanoparticles). Surface arrays of palladium nanoparticles were deposited on the nanomagnetite using a simple one-step method without the need to modify the biomineral surface, most likely due to an organic coating priming the surface for Pd adsorption, which was produced by the bacterial culture during the formation of the nanoparticles. A combination of EXAFS and XPS showed the Pd nanoparticles on the magnetite to be predominantly metallic in nature. The Pd(0)-biomagnetite was tested for catalytic activity in the Heck reaction coupling iodobenzene to ethyl acrylate or styrene. Rates of reaction were equal to or superior to those obtained with an equimolar amount of a commercial colloidal palladium catalyst, and near complete conversion to ethyl cinnamate or stilbene was achieved within 90 and 180 min, respectively.

  7. Structural Characterizations of Palladium Clusters Prepared by Polyol Reduction of [PdCl4]2− Ions

    Directory of Open Access Journals (Sweden)

    Loredana Schiavo

    2016-01-01

    Full Text Available Palladium nanoparticles are of great interest in many industrial fields, ranging from catalysis and hydrogen technology to microelectronics, thanks to their unique physical and chemical properties. In this work, palladium clusters have been prepared by reduction of [PdCl4]2− ions with ethylene glycol, in the presence of poly(N-vinyl-2-pyrrolidone (PVP as stabilizer. The stabilizer performs the important role of nucleating agent for the Pd atoms with a fast phase separation, since palladium atoms coordinated to the polymer side-groups are forced at short distances during nucleation. Quasispherical palladium clusters with a diameter of ca. 2.6 nm were obtained by reaction in air at 90°C for 2 hours. An extensive materials characterization by transmission electron microscopy (TEM, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, and other characterizations (TGA, SEM, EDS-SEM, and UV-Vis has been performed in order to evaluate the structure and oxidation state of nanopalladium.

  8. Green synthesis and characterization of polyvinyl alcohol stabilized palladium nanoparticles: effect of solvent on diameter and catalytic activity

    Science.gov (United States)

    Chowdhury, Sreya Roy; Sarathi Roy, Partha; Bhattacharya, Swapan Kumar

    2017-06-01

    Global palladium nanoparticles of different average diameters in the range 2-19 nm have been synthesized at room temperature by the reduction of K2PdCl4 in aqueous alcohols of varying composition in presence of constant proportion of polyvinyl alcohol (PVA). The synthesized nanoparticles have been characterized by different spectroscopic, microscopic and electro analytical techniques like cyclic voltammetry, chronopotentiometry, and chronoamperometry. FTIR spectroscopy detects the effect of co-solvent composition on the particle-PVA interaction involving  -OH group of the latter. X-ray diffraction study shows that the nanoparticles have both face centred cubic and hexagonal crystalline structures which may influence the catalytic capability of the synthesized palladium quantum dots. The study reveals the influence of co-solvent (ethanol) composition in monitoring the average diameter and the nature of encapsulation of palladium nanoparticles which in turn help to monitor the electro-catalytic activity of the synthesized palladium nanoparticles in reference to oxidation of ethanol in alkaline medium.

  9. Characterization of graphite-supported palladium-cobalt catalysts by temperature-programmed reduction and magnetic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Noronha, F.B.; Schmal, M. [Universidade Federal do Rio de Janeiro (Brazil); Nicot, C. [Institut de Recherches sur la Catalyse, Villeurbanne (France)] [and others

    1997-05-01

    Graphite-supported cobalt, palladium, and cobalt-palladium systems were prepared by a simple impregnation technique and submitted to hydrogen reduction in a temperature-programmed mode. Using X-ray diffraction to define the structure of the calcined precursors, magnetic measurements to determine the amount of metallic cobalt formed after reduction, and analysis of the gaseous medium during the reduction, a general model for the reduction of the graphite supported catalysts has been suggested. At room temperature, both pure PdO and PdO associated with Co{sub 3}O{sub 4} are reduced to the metallic state. In the case of bimetallic systems, a fraction of Co{sub 3}O{sub 4} in close proximity or interfaced with PdO can be reduced to the metallic state and to COO species, demonstrating a strong catalytic effect of palladium on the reduction of cobalt oxides. At temperatures between 298 and 500 K, depending on the catalyst formulation, the presence of metallic palladium promotes the reduction of a large fraction of oxidized cobalt. At higher reduction temperature, at least two competitive phenomena were detected: direct reduction of the residual oxidized cobalt by the graphite, leading to carbon monoxide and dioxide formation, and hydrogasification of the graphite catalyzed by the supported metals, leading mainly to methane formation. Together with a possible short-range palladium-activated hydrogen migration, at low and moderate temperatures, long-range migration of particles is necessary to explain the observations. These migrations, in turn, favor the formation of bimetallic particles, after reduction at 773 K. 53 refs., 5 figs., 3 tabs.

  10. Efficient Approach to Carbinol Derivatives through Palladium-Catalyzed Base-Free Addition of Aryltriolborates to Aldehydes

    Directory of Open Access Journals (Sweden)

    Kun Hu

    2017-09-01

    Full Text Available Palladium-catalyzed base-free addition of aryltriolborates to aldehydes has been developed, leading to a wide range of carbinol derivatives in good to excellent yields. The efficiency of this transformation was demonstrated by compatibility with a wide range of functional groups. The present synthetic route to carbinol derivatives could be readily scaled up to gram quantity without difficulty. Thus, this method represents a simple and practical procedure to access carbinol derivatives.

  11. Comparative analysis of the structure of palladium-based bulk metallic glasses prepared by treatment of melts with flux

    Science.gov (United States)

    Louzguine-Luzgin, D. V.; Bazlov, A. I.; Churyumov, A. Yu.; Georgarakis, K.; Yavari, A. R.

    2013-10-01

    A comparative analysis has been presented of structural features of palladium-based bulk metallic glasses prepared by argon gas casting into a copper mold after treatment of melts with a flux and studied using X-ray synchrotron radiation. The radial distribution functions have been calculated. The short-range order (in the first and second coordination shells) and the medium-range order (from the third to several subsequent coordination shells) in atomic arrangement have been analyzed.

  12. Activation and deactivation of neutral palladium(II) phosphinesulfonato polymerization catalysts

    KAUST Repository

    Rünzi, Thomas

    2012-12-10

    13C-Labeled ethylene polymerization (pre)catalysts [κ2-(anisyl)2P,O]Pd(13CH3)(L) (1-13CH3-L) (L = pyridine, dmso) based on di(2-anisyl)phosphine benzenesulfonate were used to assess the degree of incorporation of 13CH3 groups into the formed polyethylenes. Polymerizations of variable reaction time reveal that ca. 60-85% of the 13C-label is found in the polymer after already 1 min polymerization time, which provides evidence that the pre-equilibration between the catalyst precursor 1-13CH3-L and the active species 1-13CH3-(ethylene) is fast with respect to chain growth. The fraction of 1-13CH3-L that initiates chain growth is likely higher than the 60-85% determined from the 13C-labeled polymer chain ends since (a) chain walking results in in-chain incorporation of the 13C-label, (b) irreversible catalyst deactivation by formation of saturated (and partially volatile) alkanes diminishes the amount of 13CH3 groups incorporated into the polymer, and (c) palladium-bound 13CH3 groups, and more general palladium-bound alkyl(polymeryl) chains, partially transfer to phosphorus by reductive elimination. NMR and ESI-MS analyses of thermolysis reactions of 1-13CH3-L provide evidence that a mixture of phosphonium salts (13CH3)xP+(aryl)4-x (2-7) is formed in the absence of ethylene. In addition, isolation and characterization of the mixed bis(chelate) palladium complex [κ2-(anisyl)2P,O]Pd[κ2-(anisyl) (13CH3)P,O] (11) by NMR and X-ray diffraction analyses from these mixtures indicate that oxidative addition of phosphonium salts to palladium(0) species is also operative. The scrambling of palladium-bound carbyls and phosphorus-bound aryls is also relevant under NMR, as well as preparative reactor polymerization conditions exemplified by the X-ray diffraction analysis of [κ2-(anisyl)2P,O] Pd[κ2-(anisyl)(CH2CH3)P,O] (12) and [κ2-(anisyl)2P,O]Pd[κ2-(anisyl) ((CH2)3CH3)P,O] (13) isolated from pressure reactor polymerization experiments. In addition, ESI-MS analyses of reactor

  13. Silica-acac-supported palladium nanoparticles as an efficient and ...

    Indian Academy of Sciences (India)

    -supported palladium nanoparticles as an efficient and reusable heterogeneous catalyst in the Suzuki-Miyaura cross-coupling reaction in water. Abdol Reza Hajipour Zohre Shirdashtzade Ghobad Azizi. Volume 126 Issue 1 January 2014 pp ...

  14. Palladium-catalyzed asymmetric silaboration of allenes.

    Science.gov (United States)

    Ohmura, Toshimichi; Taniguchi, Hiroki; Suginome, Michinori

    2006-10-25

    An enantioselective silaboration of allenes was achieved using an achiral silylborane in the presence of a palladium catalyst bearing a chiral monodentate phosphine ligand. (R)-2-Bis(3,5-dimethylphenyl)phosphino-1,1'-binaphthyl gave the highest enantioselectivities in the addition of (diphenylmethylsilyl)pinacolborane to the internal C=C bond of terminal allenes at 0 degrees C, giving the corresponding beta-borylallylsilanes in high yields with high enantiomeric excesses. The enantioselectivity depended on the bulkiness of substituents of allenes: the enantiomeric excesses were found to be 91-93% ee (R = tert- and sec-alkyl), 88-90% ee (R = aryl), and 80-82% ee (R = prim-alkyl and Me) at 0 degrees C. Perfect chirality transfer was observed in the intramolecular cyclization reactions of the functionalized allylsilanes, affording highly enantioenriched cyclic alkenylboranes, which underwent Suzuki-Miyaura coupling with aryl halides.

  15. Scope and mechanism in palladium-catalyzed isomerizations of highly substituted allylic, homoallylic, and alkenyl alcohols.

    Science.gov (United States)

    Larionov, Evgeny; Lin, Luqing; Guénée, Laure; Mazet, Clément

    2014-12-03

    Herein we report the palladium-catalyzed isomerization of highly substituted allylic alcohols and alkenyl alcohols by means of a single catalytic system. The operationally simple reaction protocol is applicable to a broad range of substrates and displays a wide functional group tolerance, and the products are usually isolated in high chemical yield. Experimental and computational mechanistic investigations provide complementary and converging evidence for a chain-walking process consisting of repeated migratory insertion/β-H elimination sequences. Interestingly, the catalyst does not dissociate from the substrate in the isomerization of allylic alcohols, whereas it disengages during the isomerization of alkenyl alcohols when additional substituents are present on the alkyl chain.

  16. Palladium-Catalyzed Deaminative Phenanthridinone Synthesis from Aniline via C-H Bond Activation.

    Science.gov (United States)

    Yedage, Subhash L; Bhanage, Bhalchandra M

    2016-05-20

    This work reports palladium-catalyzed phenanthridinone synthesis using the coupling of aniline and amide by formation of C-C and C-N bonds in a one-pot fashion via dual C-H bond activation. It involves simultaneous cleavage of four bonds and the formation of two new bonds. The present protocol is ligand-free, takes place under mild reaction conditions, and is environmentally benign as nitrogen gas and water are the only side products. This transformation demonstrates a broad range of aniline and amide substrates with different functional groups and has been scaled up to gram level.

  17. Palladium-Catalyzed C(sp(3))-C(sp(2)) Cross-Coupling of (Trimethylsilyl)methyllithium with (Hetero)Aryl Halides.

    Science.gov (United States)

    Heijnen, Dorus; Hornillos, Valentín; Corbet, Brian P; Giannerini, Massimo; Feringa, Ben L

    2015-05-01

    The palladium-catalyzed direct cross-coupling of a range of organic chlorides and bromides with the bifunctional C(sp(3))-(trimethylsilyl)methyllithium reagent is reported. The use of Pd-PEPPSI-IPent as the catalyst allows for the preparation of structurally diverse and synthetically versatile benzyl- and allylsilanes in high yields under mild conditions (room temperature) with short reaction times.

  18. Palladium-catalyzed C-H bond carboxylation of acetanilides: an efficient usage of N,N-dimethyloxamic acid as the carboxylate source.

    Science.gov (United States)

    Wu, Yinuo; Jiang, Cheng; Wu, Deyan; Gu, Qiong; Luo, Zhang-Yi; Luo, Hai-Bin

    2016-01-21

    N,N-Dimethyloxamic acid can be successfully employed as a carboxylate precursor in the palladium-catalyzed direct C-H carboxylation of acetanilides. The reaction proceeds smoothly under mild conditions over a broad range of substrates with high functional group tolerance, affording substituted N-acyl anthranilic acids in moderate to high yields.

  19. Palladium Catalyzed Heck Arylation of 2,3-Dihydrofuran—Effect of the Palladium Precursor

    OpenAIRE

    Adam Morel; Anna M. Trzeciak; Juliusz Pernak

    2014-01-01

    Heck arylation of 2,3-dihydrofuran with iodobenzene was carried out in systems consisting of different palladium precursors (Pd2(dba)3, Pd(acac)2, PdCl2(cod), [PdCl(allyl)]2, PdCl2(PhCN)2, PdCl2(PPh3)2) and ionic liquids (CILs) with L-prolinate or L-lactate anions. All the tested CILs caused remarkable increases of the conversion values and in all of the reactions 2-phenyl-2,3-dihydrofuran (3) was obtained as the main product with a yield of up to 59.2%. The highest conversions of iodobenze...

  20. Atomistic simulation of helium bubble nucleation in palladium

    Energy Technology Data Exchange (ETDEWEB)

    Wang Liang [Department of Applied Physics, Hunan University, Changsha 410082 (China); Hu, Wangyu [Department of Applied Physics, Hunan University, Changsha 410082 (China)], E-mail: wangyuhu2001cn@yahoo.com.cn; Xiao Shifang [Department of Applied Physics, Hunan University, Changsha 410082 (China)], E-mail: sfxiao@yahoo.com.cn; Yang Jianyu [Department of Maths and Physics, Hunan Institute of Engineering, Xiangtan 411104 (China); Deng Huiqiu [Department of Applied Physics, Hunan University, Changsha 410082 (China)

    2009-09-15

    A palladium crystal has been constructed with 11808 atoms. 55 helium atoms occupied the octahedral position of palladium crystal are introduced and retained in a spherical region. Molecular dynamic simulations are performed in a constant temperature and constant volume ensemble (NVT) with temperature controlled by Nose-Hoover thermostat. The interactions between palladium atoms are described with modified analytic embedded atom method (MAEAM), the interactions between palladium atom and helium atom are in the form of Morse potential, and the interactions between helium atoms are in the form of L-J potential function. With the analysis of the radial distribution function (RDF) and microstructure, it reveals that some of helium atoms form a series of clusters with different size, and the nucleation core is random at low temperature, and which is the embryo of helium bubble. Increasing temperature can accelerate the process of bubble nucleation, and the clusters will aggregate and coalesce into a bigger one in which there are no palladium atoms, and it is considered as a helium bubble.

  1. Short Synthesis of Sulfur Analogues of Polyaromatic Hydrocarbons through Three Palladium-Catalyzed C-H Bond Arylations.

    Science.gov (United States)

    Hagui, Wided; Besbes, Néji; Srasra, Ezzeddine; Roisnel, Thierry; Soulé, Jean-François; Doucet, Henri

    2016-09-02

    An expeditious synthesis of a wide range of phenanthro[9,10-b]thiophene derivatives, which are a class of polyaromatic hydrocarbon (PAH) containing a sulfur atom, is reported. The synthetic scheme involves only two operations from commercially available thiophenes, 2-bromobenzenesulfonyl chlorides and aryl bromides. In the first step, palladium-catalyzed desulfitative arylation using 2-bromobenzenesulfonyl chlorides allows the synthesis of thiophene derivatives, which are substituted at the C4 position by an aryl group containing an ortho-bromo substituent. Then, a palladium-catalyzed one-pot cascade intermolecular C5-arylation of thiophene using aryl bromides followed by intramolecular arylation led to the corresponding phenanthro[9,10-b]thiophenes in a single operation. In addition, PAHs containing two or three sulfur atoms, as well as both sulfur and nitrogen atoms, were also designed by this strategy.

  2. Sensing performance of palladium-functionalized WO{sub 3} nanowires by a drop-casting method

    Energy Technology Data Exchange (ETDEWEB)

    Chávez, F., E-mail: f_perez_s@hotmail.com [Department of Physical-Chemical Materials, ICUAP-BUAP, 72000, Puebla (Mexico); Pérez-Sánchez, G.F. [Department of Physical-Chemical Materials, ICUAP-BUAP, 72000, Puebla (Mexico); Goiz, O. [Department of Electrical Engineering, CINVESTAV-IPN, 07360, México, D.F (Mexico); Zaca-Morán, P. [Department of Physical-Chemical Materials, ICUAP-BUAP, 72000, Puebla (Mexico); Peña-Sierra, R.; Morales-Acevedo, A. [Department of Electrical Engineering, CINVESTAV-IPN, 07360, México, D.F (Mexico); Felipe, C. [Department of Biosciences and Engineering, CIIEMAD-IPN, 07340, México, D.F (Mexico); Soledad-Priego, M. [Faculty of Electronics Sciences, FCE, 72000, Puebla (Mexico)

    2013-06-15

    In this work, we show a simple way to functionalize tungsten oxide nanowires (WO{sub 3}-NWs) using a saturated palladium chloride (PdCl{sub 2}) solution deposited by a drop-casting method. WO{sub 3}-NWs were synthesized by close-spaced chemical vapor deposition (CSVT). The morphological and structural characterizations showed that the diameters of WO{sub 3}-NWs are in the range from 50 to 200 nm with lengths above 10 μm, and correspond to the orthorhombic phase of WO{sub 3}, respectively. The sensor was fabricated using the WO{sub 3}-NWs and tested with hydrogen and volatile organic compounds (VCO's). A comparative study was done on the sensing performance, before and after the Palladium functionalization of the WO{sub 3}-NWs, considering a wide range of gas concentrations and moderate operating temperatures (100–400 °C). The results show that this simple functionalization process significantly increases the sensor sensitivity and reduces the time constants. In addition, it has been shown that at 300 °C the decorated sensor becomes more selective to hydrogen and xylene for all concentrations considered in this research. Finally, the mechanisms involved in improving the gas sensing properties of WO{sub 3}-NWs functionalized with Palladium are discussed.

  3. Granuloma possibly induced by palladium after ear piercing.

    Science.gov (United States)

    Thijs, Leen; Deraedt, Karen; Goossens, An

    2008-01-01

    A case of sarcoidal-type allergic contact granuloma due to palladium is presented. The patient developed papulonodular lesions at the right earlobe after ear piercing, which after 3 to 4 years became more granulomatous and very resistant to treatment. Repeated intralesional injections with corticosteroids produced only a temporary regression of the lesions. Patch testing revealed a strong positive reaction to palladium (and nickel). Biopsy specimens taken from the persistent granulomatous lesion in the nodule at the earlobe, as well as from the site of the positive test reaction to palladium several weeks after patch testing, indicated epithelioid granulomas with some multinucleate histiocytes surrounded by a lymphocytic-histiocytic infiltrate. Similar cases (also with other metals) have been reported in the literature.

  4. Palladium-Catalyzed Modification of Unprotected Nucleosides, Nucleotides, and Oligonucleotides

    Directory of Open Access Journals (Sweden)

    Kevin H. Shaughnessy

    2015-05-01

    Full Text Available Synthetic modification of nucleoside structures provides access to molecules of interest as pharmaceuticals, biochemical probes, and models to study diseases. Covalent modification of the purine and pyrimidine bases is an important strategy for the synthesis of these adducts. Palladium-catalyzed cross-coupling is a powerful method to attach groups to the base heterocycles through the formation of new carbon-carbon and carbon-heteroatom bonds. In this review, approaches to palladium-catalyzed modification of unprotected nucleosides, nucleotides, and oligonucleotides are reviewed. Polar reaction media, such as water or polar aprotic solvents, allow reactions to be performed directly on the hydrophilic nucleosides and nucleotides without the need to use protecting groups. Homogeneous aqueous-phase coupling reactions catalyzed by palladium complexes of water-soluble ligands provide a general approach to the synthesis of modified nucleosides, nucleotides, and oligonucleotides.

  5. Precipitation of silver/palladium alloy platelets from homogeneous solutions.

    Science.gov (United States)

    Farrell, Brendan P; Lu, Lu; Goia, Dan V

    2012-06-15

    Dispersed silver/palladium (Ag/Pd) nanoplatelets were prepared by delivering in parallel solutions of mixed metal nitrates and L-ascorbic acid into a nitric acid solution containing Arabic gum. The shape and size of bimetallic nanoparticles varied with the silver/palladium weight ratio and the concentration of nitric acid. The optimum conditions for platelets formation were a palladium content of ~2.0 wt.% and nitric acid concentrations above 1.0 mol dm(-3). The data presented show that both parameters play a critical role in the nucleation and growth of AgPd particles. A mechanism explaining the formation of the bimetallic nanoplatelets is proposed. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Palladium: a future key player in the nanomedical field?

    Science.gov (United States)

    Dumas, Anaëlle; Couvreur, Patrick

    2015-04-16

    Metal nanostructures offer invaluable possibilities for targeted drug delivery, detection/diagnosis and imaging. Whereas iron, gold, silver and platinum nanoarchitectures have largely dominated this field to date, several hurdles impede the widespread application of those nanopharmaceuticals in a clinical context. Therefore, technologies based on alternative metals are now being evaluated for their potential in medical applications. Palladium nanostructures are characterized by remarkable catalytic and optical properties. However, until recently, very few studies have taken advantage of these unique characteristics for applications in the biomedical field. Very recently, palladium nanostructures have been reported as prodrug activator, as photothermal agents and for anti-cancer/anti-microbial therapy. With only a handful of reports available, the pharmaceutical applications of palladium nanostructures reviewed here are in their infancy. Yet their interesting performance and toxicity profiles may qualify them as future key players in the nanomedical field.

  7. Size effects in electronic and catalytic properties of unsupported palladium nanoparticles in electrooxidation of formic acid.

    Science.gov (United States)

    Zhou, Wei Ping; Lewera, Adam; Larsen, Robert; Masel, Rich I; Bagus, Paul S; Wieckowski, Andrzej

    2006-07-13

    We report a combined X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and chronoamperometry (CA) study of formic acid electrooxidation on unsupported palladium nanoparticle catalysts in the particle size range from 9 to 40 nm. The CV and CA measurements show that the most active catalyst is made of the smallest (9 and 11 nm) Pd nanoparticles. Besides the high reactivity, XPS data show that such nanoparticles display the highest core-level binding energy (BE) shift and the highest valence band (VB) center downshift with respect to the Fermi level. We believe therefore that we found a correlation between formic acid oxidation current and BE and VB center shifts, which, in turn, can directly be related to the electronic structure of palladium nanoparticles of different particle sizes. Clearly, such a trend using unsupported catalysts has never been reported. According to the density functional theory of heterogeneous catalysis, and mechanistic considerations, the observed shifts are caused by a weakening of the bond strength of the COOH intermediate adsorption on the catalyst surface. This, in turn, results in the increase in the formic acid oxidation rate to CO2 (and in the associated oxidation current). Overall, our measurements demonstrate the particle size effect on the electronic properties of palladium that yields different catalytic activity in the HCOOH oxidation reaction. Our work highlights the significance of the core-level binding energy and center of the d-band shifts in electrocatalysis and underlines the value of the theory that connects the center of the d-band shifts to catalytic reactivity.

  8. Hydrogen Production via Steam Reforming of Ethyl Alcohol over Palladium/Indium Oxide Catalyst

    Directory of Open Access Journals (Sweden)

    Tetsuo Umegaki

    2009-01-01

    Full Text Available We report the synergetic effect between palladium and indium oxide on hydrogen production in the steam reforming reaction of ethyl alcohol. The palladium/indium oxide catalyst shows higher hydrogen production rate than indium oxide and palladium. Palladium/indium oxide affords ketonization of ethyl alcohol with negligible by-product carbon monoxide, while indium oxide mainly affords dehydration of ethyl alcohol, and palladium affords decomposition of ethyl alcohol with large amount of by-product carbon monoxide. The catalytic feature of palladium/indium oxide can be ascribed to the formation of palladium-indium intermetallic component during the reaction as confirmed by X-ray diffraction and X-ray photoelectron spectroscopic measurements.

  9. Palladium-Catalyzed Directed Halogenation of Bipyridine N-Oxides.

    Science.gov (United States)

    Zucker, Sina P; Wossidlo, Friedrich; Weber, Manuela; Lentz, Dieter; Tzschucke, C Christoph

    2017-06-02

    The palladium-catalyzed directed C-H halogenation of bipyridine N-oxides was investigated. Using NCS or NBS (N-chloro- or N-bromosuccinimide) and 5 mol % Pd(OAc)2 in chlorobenzene (0.10 molar) at 110 °C, pyridine-directed functionalization took place and 3-chloro- or 3-bromobipyridine N-oxides were obtained in high yields. The reaction is sensitive to steric hindrance by 4- and 6'-substituents. Only in the latter case, where coordination of palladium by the pyridine is hindered, 3'-halogenation directed by the N-oxide function was observed. The halogenated products were deoxygenated by PCl3 or PBr3.

  10. ESR, electrochemical and reactivity studies of antitrypanosomal palladium thiosemicarbazone complexes.

    Science.gov (United States)

    Otero, Lucía; Folch, Christian; Barriga, Germán; Rigol, Carolina; Opazo, Lucia; Vieites, Marisol; Gambino, Dinorah; Cerecetto, Hugo; Norambuena, Ester; Olea-Azar, Claudio

    2008-08-01

    Cyclic voltammetry (CV) and electron spin resonance (ESR) techniques were used in the investigation of novel palladium complexes with bioactive thiosemicarbazones derived from 5-nitrofurane or 5-nitrofurylacroleine. Sixteen palladium complexes grouped in two series of the formula [PdCl(2)HL] or [PdL(2)] were studied. ESR spectra of the free radicals obtained by electrolytic reduction were characterized and analyzed. The ESR spectra showed two different hyperfine patterns. The stoichiometry of the complexes does not seem to affect significantly the hyperfine constants however we observed great differences between 5-nitrofurane and 5-nitrofurylacroleine derivatives. The scavenger properties of this family of compounds were lower than Trolox.

  11. ESR, electrochemical and reactivity studies of antitrypanosomal palladium thiosemicarbazone complexes

    Science.gov (United States)

    Otero, Lucía; Folch, Christian; Barriga, Germán; Rigol, Carolina; Opazo, Lucia; Vieites, Marisol; Gambino, Dinorah; Cerecetto, Hugo; Norambuena, Ester; Olea-Azar, Claudio

    2008-08-01

    Cyclic voltammetry (CV) and electron spin resonance (ESR) techniques were used in the investigation of novel palladium complexes with bioactive thiosemicarbazones derived from 5-nitrofurane or 5-nitrofurylacroleine. Sixteen palladium complexes grouped in two series of the formula [PdCl 2HL] or [PdL 2] were studied. ESR spectra of the free radicals obtained by electrolytic reduction were characterized and analyzed. The ESR spectra showed two different hyperfine patterns. The stoichiometry of the complexes does not seem to affect significantly the hyperfine constants however we observed great differences between 5-nitrofurane and 5-nitrofurylacroleine derivatives. The scavenger properties of this family of compounds were lower than Trolox.

  12. Morphological Study Of Palladium Thin Films Deposited By Sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Salcedo, K L; Rodriguez, C A [Grupo Plasma Laser y Aplicaciones, Ingenieria Fisica, Universidad Tecnologica de Pereira (Colombia); Perez, F A [WNANO, West Virginia University (United States); Riascos, H [Grupo Plasma Laser y Aplicaciones, Departamento de Fisica, Universidad Tecnologica de Pereira (Colombia)

    2011-01-01

    This paper presents a morphological analysis of thin films of palladium (Pd) deposited on a substrate of sapphire (Al{sub 2}O{sub 3}) at a constant pressure of 3.5 mbar at different substrate temperatures (473 K, 523 K and 573 K). The films were morphologically characterized by means of an Atomic Force Microscopy (AFM); finding a relation between the roughness and the temperature. A morphological analysis of the samples through AFM was carried out and the roughness was measured by simulating the X-ray reflectivity curve using GenX software. A direct relation between the experimental and simulation data of the Palladium thin films was found.

  13. High-Valent Organometallic Copper and Palladium in Catalysis

    Science.gov (United States)

    Hickman, Amanda J.; Sanford, Melanie S.

    2015-01-01

    Preface Copper and palladium catalysts are critically important for numerous commercial chemical processes. Improvements in the activity, selectivity, and scope of these catalysts have the potential to dramatically reduce the environmental impact and increase the sustainability of chemical reactions. One rapidly emerging strategy to achieve these goals is to exploit “high-valent” copper and palladium intermediates in catalysis. This review describes exciting recent advances involving both the fundamental chemistry and the applications of these high-valent metal complexes in numerous synthetically useful catalytic transformations. PMID:22498623

  14. Phase Transitions in Even-Even Palladium Isotopes

    Directory of Open Access Journals (Sweden)

    Diab S. M.

    2009-01-01

    Full Text Available The positive and negative parity states of the even-even palladium isotopes were stud- ied within the frame work of the interacting boson approximation model (IBA-1. The energy spectra, potential energy surfaces, electromagnetic transition probabilities, back bending and staggering effect have been calculated. The potential energy surfaces show smooth transition from vibrational-like to gamma-soft and finally to rotational-like nu- clei. Staggering effectle, has been observed between the positive and negative parity states in palladium isotopes. The agreement between theoretical predictions and exper- imental values are fairly good.

  15. Morphological Study Of Palladium Thin Films Deposited By Sputtering

    Science.gov (United States)

    Salcedo, K. L.; Rodríguez, C. A.; Perez, F. A.; Riascos, H.

    2011-01-01

    This paper presents a morphological analysis of thin films of palladium (Pd) deposited on a substrate of sapphire (Al2O3) at a constant pressure of 3.5 mbar at different substrate temperatures (473 K, 523 K and 573 K). The films were morphologically characterized by means of an Atomic Force Microscopy (AFM); finding a relation between the roughness and the temperature. A morphological analysis of the samples through AFM was carried out and the roughness was measured by simulating the X-ray reflectivity curve using GenX software. A direct relation between the experimental and simulation data of the Palladium thin films was found.

  16. Preparation of Mesoporous Silica-Supported Palladium Catalysts for Biofuel Upgrade

    Directory of Open Access Journals (Sweden)

    Ling Fei

    2012-01-01

    Full Text Available We report the preparation of two hydrocracking catalysts Pd/CoMoO4/silica and Pd/CNTs/CoMoO4/silica (CNTs, carbon nanotubes. The structure, morphologies, composition, and thermal stability of catalysts were studied by X-ray diffraction (XRD, scanning electron microscopy (SEM, Raman spectroscopy, transmission electron microscopy (TEM, energy-dispersive X-ray (EDX, and thermogravimetric analysis (TGA. The catalyst activity was measured in a Parr reactor with camelina fatty acid methyl esters (FAMEs as the feed. The analysis shows that the palladium nanoparticles have been incorporated onto mesoporous silica in Pd/CoMoO4/silica or on the CNTs surface in Pd/CNTs/CoMoO4/silica catalysts. The different combinations of metals and supports have selective control cracking on heavy hydrocarbons.

  17. The biosynthesis of palladium nanoparticles by antioxidants in Gardenia jasminoides Ellis: long lifetime nanocatalysts for p-nitrotoluene hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Jia Lishan; Zhang Qian; Li Qingbiao; Song Hao, E-mail: jials@xmu.edu.c [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Key Laboratory for Chemistry and Biochemical Engineering, Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Key Laboratory for Chemical Biology of Fujian Province, Xiamen University, Xiamen 361005 (China)

    2009-09-23

    Gardenia jasminoides Ellis' water crude extract was used for the bioreduction of palladium chloride in this paper. The UV-vis spectrum, x-ray diffraction spectrum measurement, the Fourier transform infrared spectroscopy and TEM technique confirmed the formation of palladium nanoparticles and identified antioxidants including geniposide, chlorogenic acid, crocins and crocetin were reducing and stabilizing agents for synthesizing palladium nanoparticles in water crude extract. The particle size and dispersity were temperature-dependent. The particle sizes ranged from 3 to 5 nm and revealed the best dispersity at 70 {sup 0}C. Catalytic performance of the biosynthetic Pd nanoparticles with good dispersity was investigated by hydrogenation of p-nitrotoluene. The catalysts showed a conversion of 100% under conditions of 5 MPa, 150 {sup 0}C for 2 h. The selectivity of p-methyl-cyclohexylamine achieved 26.3%. The catalyst was recycled five times with no agglomeration and maintained activity, which was attributed to the appropriate protection of the antioxidants. On the basis of the study, it appears to be a new promising biosynthetic nanocatalyst for the development of an industrial process.

  18. Destruction of pentachlorobiphenyl in soil by supercritical CO(2) extraction coupled with polymer-stabilized palladium nanoparticles.

    Science.gov (United States)

    Wang, Joanna Shaofen; Chiu, KongHwa

    2009-05-01

    PCBs exhibit a wide range of toxic effects, and they are very stable compounds and do not degrade readily. Although they had been banned in the 1970s; however; it is still urgent to investigate and develop a financially viable, environmentally benign and safe technology to treat the soils contaminated by PCBs. This study investigated the feasibility of coupling of supercritical fluid carbon dioxide (ScCO(2)) extraction with polymer-stabilized palladium nanoparticles for the destruction of pentachlorinated biphenyl (2,2',4,5,5'-PCB) from contaminated sand or soil samples. The extracted 2,2',4,5,5'-PCB can be converted into non-chlorinated products by hydrodechlorination catalyzed by palladium (Pd) nanoparticles, which were stabilized in high-density polyethylene (HDPE) beads. Nearly all 2,2',4,5,5'-PCB was removed quantitatively from solid matrices at 200atm and different temperatures. The final product was proved to be biphenyl and cyclohexylbenzene. The polymer-stabilized palladium nanoparticle catalyst, which does not contact the contaminated matrix directly, can be reused without losing the high catalytic activity inherent by nanometer-sized particles. Deactivation factors such as leaching of metal particles from support, agglomeration and sintering are minimized in this catalyst system due to the unique plastic matrix environment. A combination of supercritical fluid extraction and an on-line catalytic reaction system utilizing the plastic catalysts may have great advantages over other processes for destroying toxic chlorinated compounds in environmental samples.

  19. Formation of palladium(0) nanoparticles at microbial surfaces.

    Science.gov (United States)

    Bunge, Michael; Søbjerg, Lina S; Rotaru, Amelia-Elena; Gauthier, Delphine; Lindhardt, Anders T; Hause, Gerd; Finster, Kai; Kingshott, Peter; Skrydstrup, Troels; Meyer, Rikke L

    2010-10-01

    The increasing demand and limited natural resources for industrially important platinum-group metal (PGM) catalysts render the recovery from secondary sources such as industrial waste economically interesting. In the process of palladium (Pd) recovery, microorganisms have revealed a strong potential. Hitherto, bacteria with the property of dissimilatory metal reduction have been in focus, although the biochemical reactions linking enzymatic Pd(II) reduction and Pd(0) deposition have not yet been identified. In this study we investigated Pd(II) reduction with formate as the electron donor in the presence of Gram-negative bacteria with no documented capacity for reducing metals for energy production: Cupriavidus necator, Pseudomonas putida, and Paracoccus denitrificans. Only large and close-packed Pd(0) aggregates were formed in cell-free buffer solutions. Pd(II) reduction in the presence of bacteria resulted in smaller, well-suspended Pd(0) particles that were associated with the cells (called "bioPd(0)" in the following). Nanosize Pd(0) particles (3-30 nm) were only observed in the presence of bacteria, and particles in this size range were located in the periplasmic space. Pd(0) nanoparticles were still deposited on autoclaved cells of C. necator that had no hydrogenase activity, suggesting a hydrogenase-independent formation mechanism. The catalytic properties of Pd(0) and bioPd(0) were determined by the amount of hydrogen released in a reaction with hypophosphite. Generally, bioPd(0) demonstrated a lower level of activity than the Pd(0) control, possibly due to the inaccessibility of the Pd(0) fraction embedded in the cell envelope. Our results demonstrate the suitability of bacterial cells for the recovery of Pd(0), and formation and immobilization of Pd(0) nanoparticles inside the cell envelope. However, procedures to make periplasmic Pd(0) catalytically accessible need to be developed for future nanobiotechnological applications.

  20. Palladium catalyzed heck arylation of 2,3-dihydrofuran-effect of the palladium precursor.

    Science.gov (United States)

    Morel, Adam; Trzeciak, Anna M; Pernak, Juliusz

    2014-06-19

    Heck arylation of 2,3-dihydrofuran with iodobenzene was carried out in systems consisting of different palladium precursors (Pd2(dba)3, Pd(acac)2, PdCl2(cod), [PdCl(allyl)]2, PdCl2(PhCN)2, PdCl2(PPh3)2) and ionic liquids (CILs) with L-prolinate or L-lactate anions. All the tested CILs caused remarkable increases of the conversion values and in all of the reactions 2-phenyl-2,3-dihydrofuran (3) was obtained as the main product with a yield of up to 59.2%. The highest conversions of iodobenzene were achieved for the [PdCl(allyl)]2 precursor. Formation of Pd(0) nanoparticles, representing the resting state of the catalyst, was evidenced by TEM.

  1. Palladium Catalyzed Heck Arylation of 2,3-Dihydrofuran—Effect of the Palladium Precursor

    Directory of Open Access Journals (Sweden)

    Adam Morel

    2014-06-01

    Full Text Available Heck arylation of 2,3-dihydrofuran with iodobenzene was carried out in systems consisting of different palladium precursors (Pd2(dba3, Pd(acac2, PdCl2(cod, [PdCl(allyl]2, PdCl2(PhCN2, PdCl2(PPh32 and ionic liquids (CILs with L-prolinate or L-lactate anions. All the tested CILs caused remarkable increases of the conversion values and in all of the reactions 2-phenyl-2,3-dihydrofuran (3 was obtained as the main product with a yield of up to 59.2%. The highest conversions of iodobenzene were achieved for the [PdCl(allyl]2 precursor. Formation of Pd(0 nanoparticles, representing the resting state of the catalyst, was evidenced by TEM.

  2. Palladium-109 labeled anti-melanoma monoclonal antibodies

    Science.gov (United States)

    Srivastava, S.C.; Fawwaz, R.A.; Ferrone, S.

    1984-04-30

    The invention consists of new monoclonal antibodies labelled with Palladium 109, a beta-emitting radionuclide, the method of preparing this material, and its use in the radiotherapy of melanoma. The antibodies are chelate-conjugated and demonstrate a high uptake in melanomas. (ACR)

  3. Discovery of palladium, antimony, tellurium, iodine, and xenon isotopes

    CERN Document Server

    Kathawa, J; Thoennessen, M

    2012-01-01

    Currently, thirty-eight palladium, thirty-eight antimony, thirty-nine tellurium, thirty-eight iodine, and forty xenon isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  4. RETURN ON INVESTMENT IN THE IMPERSONAL METAL ACCOUNTS OF PALLADIUM

    Directory of Open Access Journals (Sweden)

    Ivan I. Agafonov

    2014-01-01

    Full Text Available A study of investment attractiveness of investing in the precious metals market with respect to impersonal metal accounts of Palladium in the period of sustained growth of its market value over the last year. A methodology for the assessment of the return on those investments, taking into account the profitability of alternative risk-free investment.

  5. Palladium(II)-catalyzed oxidation of L-tryptophan by ...

    Indian Academy of Sciences (India)

    It is a reducing agent in chemical and biochemical systems. The rate of reduction depends on the oxidant and pH of the medium. Our literature survey reveals that ... ruthenium, osmium, palladium, manganese, chromium, and iridium, either alone or as binary mixtures, as cata- lysts in various redox processes has attracted ...

  6. STRONTIUM AS AN EFFICIENT PROMOTER FOR SUPPORTED PALLADIUM HYDROGENATION CATALYSTS

    Science.gov (United States)

    The effect of strontium promotion is studied for a series of supported palladium catalysts such as Pd/zeolite-β, Pd/Al2O3, Pd/SiO2, Pd/hydrotalcite and Pd/MgO. Strontium is found to be an effective promoter for enhancing the metal area, perce...

  7. Palladium-catalyzed allylation of α-hydroxy acids

    NARCIS (Netherlands)

    Moorlag, Hendrik; Vries, de Johannes; KAPTEIN, B; Schoemaker, Hans E.; Kamphuis, Johan; KELLOGG, RM

    Mandelic and lactic acids are converted to the 1,3-dioxolan-4-ones by treatment with acetone dimethyl acetal. Deprotonation followed by treatment with an allyl acetate and a catalytic amount (1 mol%) of palladium catalyst afforded the allylated dioxolanones, which could be hydrolyzed to the

  8. Micromachined palladium silver alloy membranes for hydrogen separation

    NARCIS (Netherlands)

    Tong, D.H.; Gielens, F.C.; Berenschot, Johan W.; de Boer, Meint J.; Gardeniers, Johannes G.E.; Jansen, Henricus V.; Nijdam, W.; van Rijn, C.J.M.; Elwenspoek, Michael Curt

    2002-01-01

    This paper presents wafer-scale palladium - silver alloy membranes, fabricated with a sequence of wellknown thin film and silicon micromachining techniques. The membranes have been tested in a gas permeation system to determine the hydrogen permeability and hydrogen selectivity. Typical flow rates

  9. Palladium-based nanocatalysts for alcohol electrooxidation in alkaline media

    CSIR Research Space (South Africa)

    Modibedi, RM

    2013-01-01

    Full Text Available in the electrocatalytic oxidation of alcohols in alkaline media compared to platinum catalysts. Recent efforts have focused on the discovery of palladium-based electrocatalysts with little or no platinum for oxygen reduction reaction (ORR). This chapter is an overview...

  10. Theoretical studies on the mechanism of palladium (II)-catalysed ...

    Indian Academy of Sciences (India)

    The mechanism of palladium(II)-catalysed carboxylation of acetanilide with CO has been investigated using density functional theory calculation done at the B3LYP/6-31G(d, p)(SDD for Pd) level of theory. Solvent effects on these reactions have been explored by calculation that included a polarizable continuum model ...

  11. Palladium-Catalysed Dimerisation of Furfural | Taljaard | South ...

    African Journals Online (AJOL)

    5,5'-Diformyl-2,2'-difuran has been synthesized in 60% yield by the palladium acetate-catalysed aryl coupling of furfural in acetonitrile in the presence of dioxygen under pressure. Various reaction conditions have been exploited, and mechanistic aspects of the reaction are discussed. South African Journal of Chemistry ...

  12. : Recyclable, ligand free palladium(II) catalyst for Heck reaction

    Indian Academy of Sciences (India)

    Abstract. Palladium substituted in cerium dioxide in the form of a solid solution, Ce0·98 Pd0·02 O1·98 is a new heterogeneous catalyst which exhibits high activity and 100% trans-selectivity for the Heck reactions of aryl bromides including heteroaryls with olefins. The catalytic reactions work without any ligand. Nano-.

  13. Palladium-catalyzed selective acyloxylation using sodium perborate as oxidant.

    Science.gov (United States)

    Pilarski, Lukasz T; Janson, Pär G; Szabó, Kálmán J

    2011-03-04

    Sodium perborate (SPB), a principal component of washing powders, was employed as an inexpensive and eco-friendly oxidant in the palladium-catalyzed C-H acyloxylation of alkenes in excellent regio- and stereochemistry. The reactions used anhydrides as acyloxy sources. The method applies to both terminal and internal alkenes, and even benzylic C-H oxidation.

  14. Study of electroplated silver-palladium biofouling inhibiting coating

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Hilbert, Lisbeth Rischel; Møller, Per

    , a new coating has been designed to form an inhibiting effect on the surface by itself. In this way, it is desired that the release of any matter will be in low concentration. This design is based on silver combined with nobler palladium, both with catalytic properties. Due to the potential difference...

  15. Study of electroplated silver-palladium biofouling inhibiting coating

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Hilbert, Lisbeth Rischel; Schroll, Casper

    2008-01-01

    Biofouling can cause many undesirable effects in industrial and medical settings. In this study, a new biofouling inhibiting Ag-Pd surface was designed to form an inhibiting effect by itself. This design was based on silver combined with nobler palladium, both with catalytic properties. Owing to ...

  16. electrocatalytic nitrate reduction on palladium based catalysts activated with germanium

    NARCIS (Netherlands)

    Gootzen, J.F.E.; Lefferts, Leonardus; van Veen, J.A.R.; van Veen, J.

    1999-01-01

    The electrocatalytic reduction of nitrate has been studied with electrochemical methods on palladium and palladium–platinum electrodes activated with germanium. The formation of a palladium–germanium alloy that occurs at germanium coverage above 0.2 has a strong enhancing effect on the rate of

  17. Hydrogen storage studies of palladium decorated nitrogen doped graphene nanoplatelets.

    Science.gov (United States)

    Vinayan, B P; Sethupathi, K; Ramaprabhu, S

    2012-08-01

    Hydrogen storage in materials is of significant importance in the present scenario of depleting conventional energy sources. Porous solids such as activated carbon or nanostructured carbon materials have promising future as hydrogen storage media. The hydrogen storage capacity in nanostructured carbon materials can be further enhanced by atomic hydrogen spillover from a supported catalyst. In the present work, the hydrogen storage properties of nitrogen doped graphene nanoplatelets (N-GNP) and palladium decorated nitrogen doped graphene nanoplatelets (Pd/N-GNP) have been investigated. The results show that hydrogen uptake capacity of nitrogen doped graphene nanoplatelets and palladium decorated nitrogen doped graphene nanoplatelets at pressure 32 bar and temperature 25 degrees C is 0.42 wt% and 1.25 wt% respectively. The dispersion of palladium nanoparticles increases the hydrogen storage capacity of nitrogen doped graphene nanoplatelets by 0.83 wt%. This may be due to high dispersion of palladium nanoparticles and strong adhesion between metal and graphene nanoplatelets over the surface of N-GNP, which enhances the spillover mechanism. Thus, an increase in the hydrogen spillover effect and the binding energy between metal nanoparticles and supporting material achieved by nitrogen doping has been observed to result in a higher hydrogen storage capacity of pristine GNP.

  18. Palladium: a future key player in the nanomedical field?

    OpenAIRE

    Dumas, Ana?lle; Couvreur, Patrick

    2015-01-01

    Metal nanostructures offer invaluable possibilities for targeted drug delivery, detection/diagnosis and imaging. Whereas iron, gold, silver and platinum nanoarchitectures have largely dominated this field to date, several hurdles impede the widespread application of those nanopharmaceuticals in a clinical context. Therefore, technologies based on alternative metals are now being evaluated for their potential in medical applications. Palladium nanostructures are characterized by remarkable cat...

  19. Chalcogenated Schiff bases: Complexation with palladium(II) and ...

    Indian Academy of Sciences (India)

    The Pd–complexes (3–4) of L6–L7 were explored for Suzuki–Miyaura coupling and found promising as 0.006 mol % of 3 is sufficient to obtain good conversion with TON up to 1.58 × 104. Keywords. Chalcogenated Schiff base; palladium; Suzuki coupling; crystal structure. 1. Introduction. Schiff bases and related compounds ...

  20. RAPID AND SENSITIVE DETERMINATION OF PALLADIUM USING HOMOGENEOUS LIQUID-LIQUID MICROEXTRACTION VIA FLOTATION ASSISTANCE FOLLOWED BY GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROMETRY

    Directory of Open Access Journals (Sweden)

    Mohammad Rezaee

    2015-05-01

    Full Text Available A method for the determination of trace amounts of palladium was developed using homogeneous liquid-liquid microextraction via flotation assistance (HLLME-FA followed by graphite furnace atomic absorption spectrometry (GFAAS. Ammonium pyrrolidine dithiocarbamate (APDC was used as a complexing agent. This was applied to determine palladium in three types of water samples. In this study, a special extraction cell was designed to facilitate collection of the low-density solvent extraction. No centrifugation was required in this procedure. The water sample solution was added to the extraction cell which contained an appropriate mixture of extraction and homogeneous solvents. By using air flotation, the organic solvent was collected at the conical part of the designed cell. Parameters affecting extraction efficiency were investigated and optimized. Under the optimum conditions, the calibration graph was linear in the range of 1.0-200 µg L-1 with a limit of detection of 0.3 µg L-1. The performance of the method was evaluated for the extraction and determination of palladium in water samples and satisfactory results were obtained. In order to verify the accuracy of the approach, the standard addition method was applied for the determination of palladium in spiked synthetic samples and satisfactory results were obtained.

  1. Palladium nanoparticles entrapped in a self-supporting nanoporous gold wire as sensitive dopamine biosensor.

    Science.gov (United States)

    Yi, Xin; Wu, Yuxuan; Tan, Guoxin; Yu, Peng; Zhou, Lei; Zhou, Zhengnan; Chen, Junqi; Wang, Zhengao; Pang, Jinshan; Ning, Chengyun

    2017-08-11

    Traced dopamine (DA) detection is critical for the early diagnosis and prevention of some diseases such as Parkinson's, Alzheimer and schizophrenia. In this research, a novel self-supporting three dimensional (3D) bicontinuous nanoporous electrochemical biosensor was developed for the detection of dopamine by Differential Pulse Voltammetry (DPV). This biosensor was fabricated by electrodepositing palladium nanoparticles (Pd) onto self-supporting nanoporous gold (NPG) wire. Because of the synergistic effects of the excellent catalytic activity of Pd and novel structure of NPG wire, the palladium nanoparticles decorated NPG (Pd/NPG) biosensor possess tremendous superiority in the detection of DA. The Pd/NPG wire biosensor exhibited high sensitivity of 1.19 μA μΜ-1, broad detection range of 1-220 μM and low detection limit up to 1 μM. Besides, the proposed dopamine biosensor possessed good stability, reproducibility, reusability and selectivity. The response currents of detection in the fetal bovine serum were also close to the standard solutions. Therefore the Pd/NPG wire biosensor is promising to been used in clinic.

  2. Quantitative analysis of cefixime via complexation with palladium(II in pharmaceutical formulations by spectrophotometry

    Directory of Open Access Journals (Sweden)

    Syed Najmul Hejaz Azmi

    2013-08-01

    Full Text Available An optimized and validated spectrophotometric method has been developed for the determination of cefixime in pharmaceutical formulations. The method is based on the complexation reaction between cefixime and palladium ion in the presence of acidic buffer solution (pH 3 in ethanol-distilled water medium at room temperature. The complex absorbed maximally at 352nm. Beer’s law is obeyed in the working concentration range of 2.5–35μg/mL with apparent molar absorptivity of 1.015×104L/molcm and Sandell’s sensitivity of 0.001μg/cm2/0.001 absorbance unit. The limits of detection and quantitation for the proposed method are 0.175 and 0.583μg/mL, respectively. The effect of common excipients used as additives has been studied in the determination of cefixime. The proposed method has been successfully applied for the determination of cefixime in pharmaceutical formulations. The results obtained by the proposed method were statistically compared with the reference method using t and F values and found no significant difference between the two methods. Keywords: Spectrophotometry, Cefixime, Palladium ion, Pd(II–cefixime complex

  3. Highly Efficient Fuel Cell Electrodes from Few-Layer Graphene Sheets and Electrochemically Deposited Palladium Nanoparticles

    CERN Document Server

    Höltig, Michael; Kipp, Tobias; Mews, Alf

    2016-01-01

    An extremely efficient ethanol fuel cell electrode is produced by combining the large surface area of vertically oriented and highly conductive few-layer graphene sheets with electrochemically deposited palladium nanoparticles. The electrodes show an extraordinary high catalyst activity of up to 7977 mA/(mg Pd) at low catalyst loadings of 0.64 $\\mu$g/cm$^2$ and a very high current density of up to 106 mA/cm$^2$ at high catalyst loadings of 83 $\\mu$g/cm$^2$. Moreover, the low onset potentials combined with a good poisoning resistance and long-term stability make these electrodes highly suitable for real applications. These features are achieved by using a newly developed electrochemical catalyst deposition process exploiting high voltages of up to 3.5 kV. This technique allows controlling the catalyst amount ranging from a homogeneous widespread distribution of small ($\\leq$ 10 nm) palladium nanoparticles to rather dense layers of particles, while every catalyst particle has electrical contact to the graphene ...

  4. A Mechanism for the Oxidation-Related Influence on the Thermoelectric Behavior of Palladium

    Science.gov (United States)

    Ohm, W.-S.; Hill, K. D.

    2010-09-01

    Oxidation of thermocouple elements can degrade the accuracy of thermocouple-based temperature measurements. As a particular example of such effects, oxidation of the Pd element of a platinum/palladium thermocouple is known to increase the thermoelectric emf by an amount equivalent to a temperature change of the order of 100 mK to 200 mK at 420 °C (G. W. Burns, D. C. Ripple, Proceedings of TEMPMEKO `96, 6th International Symposium on Temperature and Thermal Measurements in Industry and Science. Levrotto and Bella, Torino, 1997, 171-176). A possible physical mechanism to explain how oxidation affects the thermoelectric output of a Pt/Pd thermocouple is proposed. The analysis hinges on the hypothesis that the oxide-induced strain within the Pd thermoelement leads to a change in the Seebeck coefficient, and therefore to the thermoelectric emf. A theoretical model relating deformation of the palladium lattice to the change in the Seebeck coefficient is presented. The level of agreement between the calculation and the experimental observations suggests that oxide-induced strain in the Pd thermoelement is a likely explanation for the change in thermoelectric output of a Pt/Pd thermocouple within the temperature range where oxidation is active.

  5. Mild Negishi cross-coupling reactions catalyzed by acenaphthoimidazolylidene palladium complexes at low catalyst loadings.

    Science.gov (United States)

    Liu, Zelong; Dong, Ningning; Xu, Mizhi; Sun, Zheming; Tu, Tao

    2013-08-02

    Considering that the strong σ-donor property of ylidenes derived from π-extended imidazolium salts is conducive to increasing the catalytic activity of the resulting palladium N-heterocyclic carbene complexes, robust acenaphthoimidazol-ylidene palladium complexes 3a-c with varying bulky substituted groups were prepared from the corresponding acenaphthoimidazolium chlorides by heating with PdCl2 and K2CO3 in neat 3-chloropyridine in satisfactory yields. Even at a catalyst loading as low as 0.25 mol %, complex 3a exhibited extremely high catalytic activity toward Negishi cross-coupling of alkylzinc reagents with a wide range of (hetero)aryl halides under mild reaction conditions within 30 min. Besides a great number of bromoarenes, various less expensive and inactive (hetero)aryl chlorides were coupled successfully with the alkyl- and arylzinc reagents, in which active functional groups (such as -NH2) were well tolerated even in one-pot dicoupling transformations without protection. In addition, in the case of coupling with secondary alkylzinc reagents, undesired β-hydride elimination leading to isomerized linear products was efficaciously suppressed. The catalyst system also displayed superiority in the construction of heterobiaryls through the coupling of heteroarylzinc reagents and heterocylic chloroarenes which were hardly accessible from the corresponding organoboron reagents by Suzuki-coupling reactions. Therefore, the protocol described in this paper represents a mild, general, and scalable approach to access various structurally intriguing and functionalized (hetero)aryls.

  6. Green synthesis, characterization and antibacterial efficacy of palladium nanoparticles synthesized using Filicium decipiens leaf extract

    Science.gov (United States)

    Sharmila, G.; Farzana Fathima, M.; Haries, S.; Geetha, S.; Manoj Kumar, N.; Muthukumaran, C.

    2017-06-01

    Synthesis of metal nanoparticles through green chemistry route is an emerging eco-friendly approach in the present days. An eco-friendly, biogenic synthesis of palladium nanoparticles (PdNPs) using Filicium decipiens leaf extract was reported in the present study. The synthesized PdNPs were characterized by UV-visible spectroscopy, Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The PdNPs formation was confirmed by UV-visible spectrophotometer and spherical shaped PdNPs with size range of 2-22 nm was observed in TEM analysis. Energy dispersive X-ray spectroscopy (EDS) analysis confirmed the presence of palladium in the synthesized nanoparticles. The crystalline nature of PdNPs was confirmed by XRD pattern and compared with the standard. The phytochemicals and proteins were identified by their functional groups in FT-IR spectrum and revealed the amide, amine groups present in F. decipiens may have involved in the bio-reduction reaction for PdNPs synthesis. Prepared PdNPs showed potential antibacterial activity against both Gram-positive and Gram-negative bacteria. F. decipiens leaf extract based PdNPs showed high bactericidal activity against Escherichia coli, Pseudomonas aeruginosa as compared to Staphylococcus aureus and Bacillus subtilis Results showed that phytochemicals rich F. decipiens leaf extract may be utilized as an effective non-toxic reducing agent for PdNPs synthesis and prepared PdNPs may useful in biomedical applications.

  7. Palladium-Catalyzed Atom-Transfer Radical Cyclization at Remote Unactivated C(sp3)-H Sites: Hydrogen-Atom Transfer of Hybrid Vinyl Palladium Radical Intermediates.

    Science.gov (United States)

    Ratushnyy, Maxim; Parasram, Marvin; Wang, Yang; Gevorgyan, Vladimir

    2018-03-01

    A novel mild, visible-light-induced palladium-catalyzed hydrogen atom translocation/atom-transfer radical cyclization (HAT/ATRC) cascade has been developed. This protocol involves a 1,5-HAT process of previously unknown hybrid vinyl palladium radical intermediates, thus leading to iodomethyl carbo- and heterocyclic structures. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Metallurgical characterization of new palladium-containing cobalt chromium and nickel chromium alloys

    Science.gov (United States)

    Puri, Raghav

    Recently introduced to the market has been an entirely new subclass of casting alloy composition whereby palladium (˜25 wt%) is added to traditional base metal alloys such as CoCr and NiCr. Objectives. The purpose of this study was to evaluate the microstructure and Vickers hardness of two new CoPdCr and one new NiPdCr alloy and compare them to traditional CoCr and NiCr alloys. Methods. The casting alloys investigated were: CoPdCr-A (Noble Crown NF, The Argen Corporation), CoPdCr-I (Callisto CP+, Ivoclar Vivadent), NiPdCr (Noble Crown, Argen), CoCr (Argeloy N.P. Special, Argen), and NiCr (Argeloy N.P. Star, Argen). As-cast cylindrical alloy specimens were mounted in epoxy resin and prepared with standard metallographic procedures, i.e. grinding with successive grades of SiC paper and polishing with alumina suspensions. The alloys were examined with an optical microscope, SEM/EPMA, and XRD to gain insight into their microstructure, composition, and crystal structure. Vickers hardness (VHN) was measured and statistically analyzed by one way ANOVA and Tukey's HSD test (alpha=0.05). Results. Optical microscopy showed a dendritic microstructure for all alloys. The Pd-containing alloys appear to possess a more complex microstructure. SEM/EPMA showed Cr to be rather uniformly distributed in the matrix with palladium tending to be segregated apart from Mo and Ni or Co. Areas of different composition may explain the poor electrochemical results noted in previous studies. XRD suggested the main phase in the Ni-containing solutions was a face centered cubic Ni solid solution, whereas the CoCr exhibited a hexagonal crystal structure that was altered to face centered cubic when Pd was included in the composition. For Vickers hardness, the Co-containing alloys possessed a greater hardness than the Ni-containing alloys. However, the incorporation of Pd in CoCr and NiCr had only a slight effect on microhardness. Conclusion. Overall, the inclusion of palladium increases the

  9. Fexofenadine Suppresses Delayed-Type Hypersensitivity in the Murine Model of Palladium Allergy

    Directory of Open Access Journals (Sweden)

    Ryota Matsubara

    2017-06-01

    Full Text Available Palladium is frequently used in dental materials, and sometimes causes metal allergy. It has been suggested that the immune response by palladium-specific T cells may be responsible for the pathogenesis of delayed-type hypersensitivity in study of palladium allergic model mice. In the clinical setting, glucocorticoids and antihistamine drugs are commonly used for treatment of contact dermatitis. However, the precise mechanism of immune suppression in palladium allergy remains unknown. We investigated inhibition of the immune response in palladium allergic mice by administration of prednisolone as a glucocorticoid and fexofenadine hydrochloride as an antihistamine. Compared with glucocorticoids, fexofenadine hydrochloride significantly suppressed the number of T cells by interfering with the development of antigen-presenting cells from the sensitization phase. Our results suggest that antihistamine has a beneficial effect on the treatment of palladium allergy compared to glucocorticoids.

  10. Characterization of the {beta}-phase of the palladium-hydrogen equation of state

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, K.J.

    1998-07-01

    The {beta}-phase of the P-C-T curves of the palladium-hydrogen system is encountered at high pressures of gaseous hydrogen and low temperatures of this system. The {beta}-phase is characterized by an increase in the concentration of hydrogen in the palladium lattice with an increase in pressure of the free hydrogen gas surrounding the palladium. The P-C-T curves in this study are determined by gravimetric measurements of the hydrided palladium sample to determine the amount of hydrogen within the palladium lattice. The amount of hydrogen is kept constant within the experimental system and the temperature is varied which changes the pressures. The objective of this experimental thesis is to accurately determine the P-C-T curves of palladium in the {beta}-phase region to pressures of 20,000 psia and medium to low temperature region of {minus}60 C to 100 C.

  11. Cyclotron production of no-carrier-added palladium-103 by bombardment of rhodium-103 target.

    Science.gov (United States)

    Chunfu, Z; Yongxian, W; Yongping, Z; Xiuli, Z

    2001-10-01

    Electroplated rhodium foil was employed as the target for cyclotron production of palladium-103. An electrodissolution apparatus was found better than other dissolution methods in terms of personnel shielding and palladium-103 yield. The ion-exchange column chromatography method was simple and effective for the purification of palladium-103 and the final stripping agent of NH4Cl + NH3(1:1) was more efficient than other agents.

  12. Palladium-Based Electrocatalysts for Alcohol Oxidation in Direct Alcohol Fuel Cells

    Science.gov (United States)

    Bianchini, C.

    Palladium is emerging as an attractive replacement for platinum in a number of electrochemical applications, including lowtemperature fuel cells, electrolyzers and sensors. Palladium is more abundant in nature and less expensive than platinum.1 However, cost-associated issues are not the main driving force behind the increasing interest in palladium as it remains a rare noble metal whose introduction for a broad technological use would lead to an irreversible increase in its market price.

  13. Carbon-Carbon Cross Coupling Reactions in Ionic Liquids Catalysed by Palladium Metal Nanoparticles

    Directory of Open Access Journals (Sweden)

    Martin H. G. Prechtl

    2010-05-01

    Full Text Available A brief summary of selected pioneering and mechanistic contributions in the field of carbon-carbon cross-coupling reactions with palladium nanoparticles (Pd-NPs in ionic liquids (ILs is presented. Five exemplary model systems using the Pd-NPs/ILs approach are presented: Heck, Suzuki, Stille, Sonogashira and Ullmann reactions which all have in common the use of ionic liquids as reaction media and the use of palladium nanoparticles as reservoir for the catalytically active palladium species.

  14. Low-temperature carbon monoxide oxidation catalysed by regenerable atomically dispersed palladium on alumina

    National Research Council Canada - National Science Library

    Peterson, Eric J; DeLaRiva, Andrew T; Lin, Sen; Johnson, Ryan S; Guo, Hua; Miller, Jeffrey T; Hun Kwak, Ja; Peden, Charles H F; Kiefer, Boris; Allard, Lawrence F; Ribeiro, Fabio H; Datye, Abhaya K

    2014-01-01

    .... Aberration-corrected scanning transmission electron microscopy and operando X-ray absorption spectroscopy confirm the presence of intermingled palladium and lanthanum on the γ-alumina surface...

  15. Adlayers of palladium particles and their aggregates on porous polypropylene hollow fiber membranes as hydrogenization contractors/reactors

    NARCIS (Netherlands)

    Volkov, V.V.; Lebedeva, V.I.; Petrova, I.V.; Bobyl, A.V.; Konnikov, S.G.; Roldughin, V.I.; Erkel, J. van; Tereshchenko, G.F.

    2011-01-01

    Principal approaches for the preparation of catalytic membrane reactors based on polymer membranes containing palladium nanoparticles and for the description of their characteristics are presented. The method for the development of adlayers composed of palladium nanoparticles and their aggregates on

  16. Adsorption and growth of palladium clusters on graphdiyne.

    Science.gov (United States)

    Seif, A; López, M J; Granja-DelRío, A; Azizi, K; Alonso, J A

    2017-07-26

    The density functional formalism has been used to investigate the stability and the properties of small palladium clusters supported on graphdiyne layers. The large triangular holes existing on the graphdiyne structure provide efficient sites to hold the clusters at small distances from the plane of the graphdiyne layer. The cluster adsorption energies, between 3 and 4 eV, are large enough to maintain the clusters tightly bound to the triangular holes. The competition between dispersion of Pd atoms on graphdiyne and growth of Pd clusters in the triangular holes of the layer is also discussed. In addition, the triangular holes can be simultaneously decorated with clusters on both sides. This indicates that palladium clusters could be used to build nanostructures formed by stacked graphdiyne layers with tailored interlayer distances controlled by the size of the clusters. The size of the clusters also controls the electronic HOMO-LUMO gap of the material.

  17. Catalytically efficient palladium nanoparticles stabilized by "click" ferrocenyl dendrimers.

    Science.gov (United States)

    Ornelas, Cátia; Salmon, Lionel; Aranzaes, Jaime Ruiz; Astruc, Didier

    2007-12-14

    1,2,3-Ferrocenyl triazole ligands generated by click reactions in dendrimers bind Pd(OAc)2 with a systematic one-to-one stoichiometry as monitored by titration using the ferrocenyl redox sensor attached to the triazole ring, and the dendritic PdII complexes formed are best reduced by methanol to form palladium nanoparticles of designed types and sizes that show excellent efficiency and selectivity in olefin hydrogenation.

  18. Thermal desorption spectroscopy of palladium and copper on silica

    Science.gov (United States)

    Pierce, Daniel E.; Burns, Richard P.; Gabriel, Kenneth A.

    Thermal desorption spectroscopy of palladium and copper films grown on clean silica substrates was performed using CO2 laser heating. After cleaning the surface by high temperature heating, a controlled, low coverage dose of metal atoms was deposited on the substrate. Temperature ramping was achieved using a constant laser power, the value of which depended on the nature of the metal and substrate as well as the substrate size. At high temperatures (above 1025 K for palladium and above 975 K for copper), metal films vaporize and desorption spectra provide information about the nature of the metal deposit and metal-support interaction. With increasing coverage of palladium on silica, a positive temperature shift in the leading edge of desorption was seen. At higher coverages, above about 2 x 10(exp 15) atoms/sq cm, a common leading edge appears and zero-order kinetic analysis gave E(sub act) values between 3.9 and 4.3 +/- 0.1 eV which can be compared with the value of 3.83 eV for Delta (H(sub vap)) (1200 K) for palladium metal. Similar coverage-dependent properties were not seen for copper on silica; instead, a common desorption leading edge appeared down to submonolayer coverages. Zero-order analysis at about 1 x 10(exp 15) atoms/sq cm gave an E(sub act) of 3.3 +/- 0.1 eV, which is comparable with the value of 3.44 eV for Delta (H(sub vap)) (1100 K) for copper metal.

  19. Palladium: a future key player in the nanomedical field?

    OpenAIRE

    Dumas Anaelle; Couvreur Patrick

    2015-01-01

    Metal nanostructures offer invaluable possibilities for targeted drug delivery detection/diagnosis and imaging. Whereas iron gold silver and platinum nanoachitectures have largely dominated this field to date several hurdles impede the widespread application of those nanopharmaceuticals in a clinical context. Therefore technologies based on alternative metals are now evaluated for their potential in medical applications. Palladium nanostructures are characterized by remarkable catalytic and o...

  20. Unsupported palladium alloy membranes and methods of making same

    Science.gov (United States)

    Way, J. Douglas; Thoen, Paul; Gade, Sabina K.

    2015-06-02

    The invention provides support-free palladium membranes and methods of making these membranes. Single-gas testing of the unsupported foils produced hydrogen permeabilities equivalent to thicker membranes produced by cold-rolling. Defect-free films as thin as 7.2 microns can be fabricated, with ideal H.sub.2/N.sub.2 selectivities as high as 40,000. Homogeneous membrane compositions may also be produced using these methods.

  1. Arsenic (III Adsorption Using Palladium Nanoparticles from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Farzaneh Arsiya

    2017-07-01

    Full Text Available The presence of Arsenic in drinking water is the greatest threat to health effects especially in water. The purpose of this study is application of green palladium nanoparticles for removal of trivalent Arsenic from aqueous solutions and also the impact of some factors such as retention time, pH, concentration of palladium nanoparticles and Arsenic concentrations was studied. The values for Arsenic removal from aqueous solutions were measured by furnace atomic adsorption spectrometry (Conter AA700. In the study, Langmuir and Freundlich isotherm models and pseudo-second order kinetic model were studied. The results of  optimization is shown that 0.5 g of nanoparticles can removed %99.8 of Arsenic with initial concentration of  0.5 g/l, in 5 minutes at pH=4. Langmuir model, Freundlich model (R2=0.94 and pseudo-second order kinetic model (R2=0.99 shown high correlation for removing of Arsenic from aqueous solutions. It was found, palladium nanoparticles can be used as an efficient method to remove Arsenic from aqueous solutions in a short time.

  2. Effects of palladium on the optical and hydrogen sensing characteristics of Pd-doped ZnO nanoparticles

    Science.gov (United States)

    Giang, Hong Thai; Do, Thu Thi; Pham, Ngan Quang; Ho, Giang Truong

    2014-01-01

    Summary The effect of palladium doping of zinc oxide nanoparticles on the photoluminescence (PL) properties and hydrogen sensing characteristics of gas sensors is investigated. The PL intensity shows that the carrier dynamics coincides with the buildup of the Pd-related green emission. The comparison between the deep level emission and the gas sensing response characteristics allows us to suggest that the dissociation of hydrogen takes place at PdZn-vacancies ([Pd 2+(4d9)]). The design of this sensor allows for a continuous monitoring in the range of 0–100% LEL H2 concentration with high sensitivity and selectivity. PMID:25247110

  3. Effects of palladium on the optical and hydrogen sensing characteristics of Pd-doped ZnO nanoparticles

    Directory of Open Access Journals (Sweden)

    Anh-Thu Thi Do

    2014-08-01

    Full Text Available The effect of palladium doping of zinc oxide nanoparticles on the photoluminescence (PL properties and hydrogen sensing characteristics of gas sensors is investigated. The PL intensity shows that the carrier dynamics coincides with the buildup of the Pd-related green emission. The comparison between the deep level emission and the gas sensing response characteristics allows us to suggest that the dissociation of hydrogen takes place at PdZn-vacancies ([Pd 2+(4d9]. The design of this sensor allows for a continuous monitoring in the range of 0–100% LEL H2 concentration with high sensitivity and selectivity.

  4. Single-Step Synthesis of Styryl Phosphonic Acids via Palladium-Catalyzed Heck Coupling of Vinyl Phosphonic Acid with Aryl Halides

    Energy Technology Data Exchange (ETDEWEB)

    Sellinger, Alan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); McNichols, Brett W. [Colorado School of Mines; United States Air Force Academy; Koubek, Joshua T. [Colorado School of Mines

    2017-10-27

    We have developed a single step palladium-catalyzed Heck coupling of aryl halides with vinyl phosphonic acid to produce functionalized (E)-styryl phosphonic acids. This pathway utilizes a variety of commercially available aryl halides, vinyl phosphonic acid and Pd(P(tBu)3)2 as catalyst. These conditions produce a wide range of styryl phosphonic acids with high purities and good to excellent yields (31-80%).

  5. Electron Transfer at Platinum and Palladium Interfaces in Super-Dry Electrolytes. Generation of Iono-Metallic Layers. A Mini-Review

    OpenAIRE

    Simonet, Jacques

    2015-01-01

    International audience; Metallic electrodes (gold, platinum) have been considered for long as inert and quasi-ideal electrodes both within the anodic and cathodic ranges. Here are gathered some striking evidences of the reactivity of platinum (and accessorily that of palladium) in aprotic polar solvents (water present < 200 ppm) for leading, by cathodic reaction with present electrolytes, to a large panel of iono-metallic layer. These modified metal layers may present many interesting behavio...

  6. In-situ synthesis of palladium nanoparticles-filled carbon nanotubes using arc-discharge in solution

    NARCIS (Netherlands)

    Bera, D; Kuiry, SC; McCutchen, M; Kruize, A; Heinrich, H; Meyyappan, M; Seal, S

    2004-01-01

    A unique, simple, inexpensive and one-step synthesis route of carbon nanotubes (CNT) supported palladium nanoparticles using a simplified arc-discharge in solution is reported. Palladium nanoparticles with 3 nm diameter were found to form during reduction of palladium tetra-chloro-square-planar

  7. A simple one-pot strategy to platinum-palladium@palladium core-shell nanostructures with high electrocatalytic activity

    Science.gov (United States)

    Lv, Jing-Jing; Zheng, Jie-Ning; Wang, Ying-Ying; Wang, Ai-Jun; Chen, Li-Li; Feng, Jiu-Ju

    2014-11-01

    Well-defined platinum-palladium@palladium core-shell nanospheres (PtPd@Pd NSs) are synthesized by a facile one-pot solution approach using N-methylimidazole and poly(vinyl pyrrolidone) (PVP) as directing and capping agents, respectively, without using any seed, template, or organic solvent. The coexistence of the precursors, N-methylimidazole, PVP, and reaction temperature has great effects on the final morphology. Thus-prepared nanocomposites display an improved electrocatalytic activity for oxygen reduction reaction (ORR) in acidic media, methanol and ethylene glycol oxidation reaction in alkaline media, compared with Pt nanoparticles, Pd nanoparticles, commercial Pt black and Pd black catalysts. This method may direct a general orientation for shape control synthesis of functional bimetallic nanocrystals as promising electrocatalysts in direct alcohol fuel cells (DAFCs).

  8. New Palladium-Catalyzed Approaches to Heterocycles and Carbocycles

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qinhua [Iowa State Univ., Ames, IA (United States)

    2004-12-19

    The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I2, ICl, PhSeCl, PhSCl and p-O2NC6H4SCl to give the corresponding halogen-, selenium- and sulfur-containing disubstituted isoquinolines and naphthyridines, respectively. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. This methodology accommodates a variety of iminoalkynes and affords the anticipated heterocycles in moderate to excellent yields. The Pd(II)-catalyzed cyclization of 2-(1-alkynyl)arylaldimines in the presence of various alkenes provides an efficient way to synthesize a variety of 4-(1-alkenyl)-3-arylisoquinolines in moderate to excellent yields. The introduction of an ortho-methoxy group on the arylaldimine promotes the Pd-catalyzed cyclization and stabilizes the resulting Pd(II) intermediate, improving the yields of the isoquinoline products. Highly substituted naphthalenes have been synthesized by the palladium-catalyzed annulation of a variety of internal alkynes, in which two new carbon-carbon bonds are formed in a single step under relatively mild reaction conditions. This method has also been used to synthesize carbazoles, although a higher reaction temperature is necessary. The process involves arylpalladation of the alkyne, followed by intramolecular Heck olefination and double bond isomerization. This method accommodates a variety of functional groups and affords the anticipated highly substituted naphthalenes and carbazoles in good to excellent yields. Novel palladium migratiodarylation methodology for the synthesis of complex fused polycycles has been developed, in which one or more sequential Pd-catalyzed intramolecular migration processes involving C-H activation are employed. The chemistry works best with electron-rich aromatics, which is in agreement

  9. Study of microstructure in vanadium–palladium alloys by X-ray ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 30; Issue 5. Study of microstructure in vanadium–palladium alloys by X-ray diffraction technique ... Present study considers microstructural characterization of vanadium-based palladium (V–Pd) alloys, which are widely used in marine environment due to their high ...

  10. Palladium complexes of a new type of N-heterocyclic carbene ligand ...

    Indian Academy of Sciences (India)

    23−25% yield. The new tricyclic triazolooxazine derived N-heterocyclic carbene moiety, as stabilized upon binding to palladium in the (1−2)b complexes, was structurally characterized by the X-ray single crystal diffraction studies. Keywords. Palladium; tricyclic triazolooxazine derived N-heterocyclic carbene (NHC); PEPPSI.

  11. Novel phosphite palladium complexes and their application in C-P cross-coupling reactions

    NARCIS (Netherlands)

    Li, J.; Lutz, M.; Spek, A.L.; van Klink, G.P.M.; van Koten, G.; Klein Gebbink, R.J.M.

    2010-01-01

    A mono- and a 1,3-bis-phosphite arene ligand based on 2,20-biphenol have been synthesized in order to study the synthesis of the corresponding palladium(II) complexes starting from different Pd precursors. Novel bis-phosphite palladium complex 1 [PdCl2(L)2] (L¼ dibenzo[d,f][1,3,2]dioxaphosphepin,

  12. Carbon nanotubes decorated with palladium nanoparticles : Synthesis, characterization, and catalytic activity

    NARCIS (Netherlands)

    Karousis, Nikolaos; Tsotsou, Georgia-Eleni; Evangelista, Fabrizio; Rudolf, Petra; Ragoussis, Nikitas; Tagmatarchis, Nikos

    2008-01-01

    In this article, the in situ preparation of palladium nanoparticles, as mediated by the self-regulated reduction of palladium acetate with the aid of sodium dodecyl sulfate (SDS), followed by subsequent deposition onto single-walled carbon nanotubes and multimalled carbon nanotubes (MWCNTs), is

  13. Borylation of Olefin C-H Bond via Aryl to Vinyl Palladium 1,4-Migration.

    Science.gov (United States)

    Hu, Tian-Jiao; Zhang, Ge; Chen, Ya-Heng; Feng, Chen-Guo; Lin, Guo-Qiang

    2016-03-09

    The aryl to vinyl palladium 1,4-migration was realized for the first time. The generated alkenyl palladium species was trapped by diboron reagents under Miyaura borylation conditions, providing a new method to synthesize β,β-disubstituted vinylboronates. The excellent regioselectivity and broad substrate scope were observed for this novel transformation.

  14. Hydrogen- Bond- Assisted Activation of Allylic Alcohols for Palladium- Catalyzed Coupling Reactions

    NARCIS (Netherlands)

    Gumrukcu, Y.; de Bruin, B.; Reek, J.

    2014-01-01

    We report direct activation of allylic alcohols using a hydrogen-bond-assisted palladium catalyst and use this for alkylation and amination reactions. The novel catalyst comprises a palladium complex based on a functionalized monodentate phosphoramidite ligand in combination with urea additives and

  15. Interstitial modification of palladium nanoparticles with boron atoms as a green catalyst for selective hydrogenation

    Science.gov (United States)

    Chan, Chun Wong Aaron; Mahadi, Abdul Hanif; Li, Molly Meng-Jung; Corbos, Elena Cristina; Tang, Chiu; Jones, Glenn; Kuo, Winson Chun Hsin; Cookson, James; Brown, Christopher Michael; Bishop, Peter Trenton; Tsang, Shik Chi Edman

    2014-12-01

    Lindlar catalysts comprising of palladium/calcium carbonate modified with lead acetate and quinoline are widely employed industrially for the partial hydrogenation of alkynes. However, their use is restricted, particularly for food, cosmetic and drug manufacture, due to the extremely toxic nature of lead, and the risk of its leaching from catalyst surface. In addition, the catalysts also exhibit poor selectivities in a number of cases. Here we report that a non-surface modification of palladium gives rise to the formation of an ultra-selective nanocatalyst. Boron atoms are found to take residence in palladium interstitial lattice sites with good chemical and thermal stability. This is favoured due to a strong host-guest electronic interaction when supported palladium nanoparticles are treated with a borane tetrahydrofuran solution. The adsorptive properties of palladium are modified by the subsurface boron atoms and display ultra-selectivity in a number of challenging alkyne hydrogenation reactions, which outclass the performance of Lindlar catalysts.

  16. Development of anodic stripping voltametry for the determination of palladium in high level nuclear waste

    Energy Technology Data Exchange (ETDEWEB)

    Bhardwaj, T. K. [North Carolina State University, Raleigh (United States); Sharma, H. S.; Affarwal, S. K. [Bhabha Atomic Research Centre, Mumbai (India); Jain, P. C. [Meerut College, Meerut (India)

    2012-12-15

    Deposition potential, deposition time, square wave frequency, rotation speed of the rotating disc electrode, and palladium concentration were studied on a Glassy Carbon Electrode (GCE) in 0.01M HCl for the determination of palladium in High Level Nuclear Waste (HLNW) by anodic stripping voltammetry. Experimental conditions were optimized for the determination of palladium at two different, 10-8 and 10-7 M, levels. Error and standard deviation of this method were under 1% for all palladium standard solutions. The developed technique was successfully applied as a subsidiary method for the determination of palladium in simulated high level nuclear waste with very good precision and high accuracy (under 1 % error and standard deviation).

  17. The Effect of Palladium Additions on the Solidus/Liquidus Temperatures and Wetting Properties of Ag-CuO Based Air Brazes

    Energy Technology Data Exchange (ETDEWEB)

    Darsell, Jens T.; Weil, K. Scott

    2007-05-16

    As a means of increasing the use temperature of ceramic-ceramic and ceramic-metal air brazes, palladium was investigated as possible ternary addition to the currently employed silver - copper oxide system. The silver component was directly substituted with palladium to form the following series of alloys: (100-y)[(100-z)Pd - (z)Ag] - (y)CuOx where y = 0 - 34 mol% CuOx, z = 50 - 100 mol% silver, and x = 0, 0.5, and 1, denoting copper metal, Cu2O, or CuO. From differential scanning calorimetry, it was determined that the addition of palladium causes an increase in the solidus and liquidus temperatures of the resulting Pd-Ag-CuO brazes. In general, the liquidus was found to increase by approximately 220°C for the (100-y)(25Pd - 75Ag) - (z)CuOx filler metal compositions relative to comparable Ag-CuOx alloys. Likewise, the solidus was found to increase for these alloys, respectively by 185°C and 60°C, respectively for CuOx contents of y = 0 - 1mol% and 4 - 10 mol%. For the (100-y)(50Pd - 50Ag) - (y)CuOx alloys, the solidus increased between 280 - 390°C over a copper oxide compositional range of x = 0 to 8 mol%. It was determined from sessile drop experiments conducted on alumina substrates that in all cases the palladium causes an increase in the wetting angle relative to the corresponding binary braze. Alloy compositions of (100-y)(25Pd - 75Ag) - (y)CuOx displayed increased wetting angles of 5-20° relative to comparable binary compositions. (100-y)(50Pd - 50Ag) - (y)CuOx alloys exhibited an increase in contact angle of 10-60° and compositions containing less than 10 mol% CuOx were not able to wet the substrate. Scanning electron microscopy indicated that the microstructure of the braze consists of discrete CuOx precipitates in an alloyed silver-palladium matrix. In both the binary and ternary filler metal formulations, a reaction layer consisting of CuAlO2 was observed along the interface with the alumina substrate. This reaction product appears to be beneficial

  18. A DFT study of arsine adsorption on palladium doped graphene: Effects of palladium cluster size

    Energy Technology Data Exchange (ETDEWEB)

    Kunaseth, Manaschai, E-mail: manaschai@nanotec.or.th [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA) , Pathum Thani 12120 (Thailand); Mudchimo, Tanabat [Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Ubon Ratchathani University, Ubon Ratchathani 34190 (Thailand); Namuangruk, Supawadee [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA) , Pathum Thani 12120 (Thailand); Kungwan, Nawee [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Promarak, Vinich [Department of Material Science and Engineering, School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Rayong 21201 (Thailand); Jungsuttiwong, Siriporn, E-mail: siriporn.j@ubu.ac.th [Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Ubon Ratchathani University, Ubon Ratchathani 34190 (Thailand)

    2016-03-30

    Graphical abstract: The relationship between charge difference and adsorption strength demonstrates that charge migration from Pd{sub n}-SDG to AsH{sub x} significantly enhanced adsorption strength, the Pd{sub 6} clusters doped SDG with a steep slope is recommended as a superior adsorbent material for AsH{sub 3} removal from gas stream. - Highlights: • Pd atom and Pd clusters bind strongly onto the defective graphene surface. • Larger size of Pd cluster adsorbs arsine and its hydrogenated products stronger. • Order of adsorption strength on Pd{sub n} doped graphene: As > AsH > AsH{sub 2} > > AsH{sub 3}. • Charge migration characterizes the strong adsorption of AsH{sub 2}, AsH, and As. • Pd cluster doped graphene is thermodynamically preferable for arsine removal. - Abstract: In this study, we have investigated the size effects of palladium (Pd) doped single-vacancy defective graphene (SDG) surface to the adsorption of AsH{sub 3} and its dehydrogenated products on Pd using density functional theory calculations. Here, Pd cluster binding study revealed that Pd{sub 6} nanocluster bound strongest to the SDG surface, while adsorption of AsH{sub x} (x = 0–3) on the most stable Pd{sub n} doped SDG showed that dehydrogenated arsine compounds adsorbed onto the surface stronger than the pristine AsH{sub 3} molecule. Charge analysis revealed that considerable amount of charge migration from Pd to dehydrogenated arsine molecules after adsorption may constitute strong adsorption for dehydrogenated arsine. In addition, study of thermodynamic pathways of AsH{sub 3} dehydrogenation on Pd{sub n} doped SDG adsorbents indicated that Pd cluster doping on SDG adsorbent tends to be thermodynamically favorable for AsH{sub 3} decomposition than the single-Pd atom doped SDG. Hence, our study has indicated that Pd{sub 6} clusters doped SDG is more advantageous as adsorbent material for AsH{sub 3} removal.

  19. Growth of nanoparticles in hydrogen-implanted palladium subsurfaces

    Energy Technology Data Exchange (ETDEWEB)

    Okuyama, F. [Nagoya Institute of Technology, Graduate School of Engineering, Nagoya (Japan)

    2010-07-15

    Solid particles with nanometric dimensions are shown to grow in the opened subsurface of a polycrystalline palladium (Pd) hydrogen-implanted at around 500 C. The particles are Pd in main composition and densely grown on sloping walls of fissured grain boundaries or cracks. The average grain size increases from deeper to shallow regions, suggesting that a negative temperature gradient toward the surface existed along the crack walls. The nanoparticles are certain to arise from the condensation of Pd vapors on the walls, forcing us to assume that hydrogen atoms implanted in an overpopulation heated their implantation zone so strongly as to vaporize Pd. (orig.)

  20. Palladium nanoparticles on InP for hydrogen detection

    Directory of Open Access Journals (Sweden)

    Zdansky Karel

    2011-01-01

    Full Text Available Abstract Layers of palladium (Pd nanoparticles on indium phosphide (InP were prepared by electrophoretic deposition from the colloid solution of Pd nanoparticles. Layers prepared by an opposite polarity of deposition showed different physical and morphological properties. Particles in solution are separated and, after deposition onto the InP surface, they form small aggregates. The size of the aggregates is dependent on the time of deposition. If the aggregates are small, the layer has no lateral conductance. Forward and reverse I-V characteristics showed a high rectification ratio with a high Schottky barrier height. The response of the structure on the presence of hydrogen was monitored.

  1. Green Chemistry Approach for Synthesis of Effective Anticancer Palladium Nanoparticles

    OpenAIRE

    Sangiliyandi Gurunathan; EunSu Kim; Jae Woong Han; Jung Hyun Park; Jin-Hoi Kim

    2015-01-01

    The purpose of this study was to design and synthesize Palladium nanoparticles (PdNPs) using an environmentally friendly approach and evaluate the in vitro efficacy of PdNPs in human ovarian cancer A2780 cells. Ultraviolet-Visible (UV-Vis) spectroscopy was used to monitor the conversion of Pd(II) ions to Pd(0)NPs. X-ray diffraction (XRD) revealed the crystallinity of the as-synthesized PdNPs and Fourier transform infrared spectroscopy (FTIR) further confirmed the role of the leaf extract of E...

  2. Synthesis of Dihydrobenzofurans via Palladium-Catalyzed Heteroannulations

    Energy Technology Data Exchange (ETDEWEB)

    Rozhkov, Roman Vladimirovich [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    Palladium-catalyzed heteroannulation of 1,3-dienes with 3-iodo-2-alkenols, and 2-iodo-2-alkenols, as well as their amino analogs, affords the corresponding cyclic ethers and amines respectively. The presence of a β-hydrogen in the vinylic halide results in β-hydride elimination giving the corresponding alkyne. The presence of a bulky group in the α-position of the vinylic halide results in failure or reduced amounts of annulation products. A chloride source, pyridine base and electron-rich phosphine are essential for this reaction.

  3. Palladium-Catalyzed alpha-Arylation of Tetramic Acids

    DEFF Research Database (Denmark)

    Storgaard, Morten; Dorwald, F. Z.; Peschke, B.

    2009-01-01

    A mild, racemization-free, palladium-Catalyzed alpha-arylation of tetramic acids (2,4-pyrrolidinediones) has been developed. Various amino acid-derived tetramic acids were cleanly arylated by treatment with 2 mol % of Pd(OAc)(2), 4 mol % of a sterically demanding biaryl phosphine, 2.3 equiv of K2...... no effect on their reactivity: both electron-rich and electron-poor aryl chlorides and bromides or triflates led to good yields. Ortho-substituted aryl halides and heteroaryl halides, however, did not undergo the title reaction....

  4. Noneffervescent Method for Catalysis-Based Palladium Detection with Color or Fluorescence.

    Science.gov (United States)

    Nieberding, Matthew; Tracey, Matthew P; Koide, Kazunori

    2017-11-22

    Palladium is a highly valuable metal in automobile, chemical, and pharmaceutical industries. The metal is generally quantified by atomic absorption spectrometry or inductively coupled plasma mass spectrometry. These techniques are tedious and require expensive instruments that are operated mostly off site. As cost-effective and user-friendly alternatives to these techniques, we previously reported two practical fluorometric or colorimetric methods to quantify palladium. Both methods rely on the use of NaBH 4 , which cannot be stored in solution for more than 10 days. Commercially available solutions of NaBH 4 are partially or fully degraded to di- or triborohydride species and cannot be used for palladium(0)-catalyzed allylic C-O bond cleavage for quantification purposes. Here, we report a new method that replaces NaBH 4 with NH 2 NH 2 for the palladium-catalyzed deallylation of fluorogenic and colorimetric chemodosimeter resorufin allyl ether. This method is slower but as sensitive as the most recent method from our laboratory. The method is selective for palladium and depends on the presence of tri(2-furyl)phosphine as a palladium ligand and NH 2 NH 2 as a palladium-reducing reagent.

  5. Magnetically recyclable reduced graphene oxide nanosheets/magnetite-palladium aerogel with superior catalytic activity and reusability.

    Science.gov (United States)

    Feng, Yan; Zhang, Hui; Xin, Baifu; Wu, Jie

    2017-11-15

    A two-step method was employed to synthesize reduced graphene oxide nanosheets/magnetite-palladium (rGSs/Fe3O4-Pd) aerogel, with excellent catalytic activity and recyclability. Firstly, graphene oxide nanosheet (GS) hydrogels were formed by the self-assembly of GSs during the hydrothermal process. Meanwhile, hematite (α-Fe2O3) and Pd nanoparticles (NPs) were synthesized and anchored onto the surface of the hydrogel. During heat-treatment, GSs were reduced to rGSs, while nonmagnetic α-Fe2O3NPs were converted to magnetic Fe3O4 NPs. The as-obtained rGSs/Fe3O4-Pd aerogel displayed a three-dimensional interconnected hierarchical porous architecture, which was rich in mesopores and macropores. Such a structure was suitable for catalysis, since it not only improved the mass diffusion and transport, but also readily exposed the catalytic Pd NPs to the reactants. The typical reduction of 4-nitrophenol was chosen as a model reaction to evaluate the catalytic performance of the aerogel. As anticipated, both the reaction rate constant and turn over frequency of the aerogel were much higher than those of the commercial Pd/C catalyst. Moreover, due to incorporation of Fe3O4 NPs, the rGSs/Fe3O4-Pd aerogel could be magnetically separated from the reaction solution and reused, without obvious loss of catalytic activity. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Palladium sulphide (PdS) films as a new thermoelectric sulphide compound

    Energy Technology Data Exchange (ETDEWEB)

    Ares, J.R.; Diaz-Chao, P.; Clamagirand, J.; Macia, M.D.; Ferrer, I.J.; Sanchez, C. [Universidad Autonoma de Madrid (Spain). Lab. de Materiales de Interes en Energias Renovables

    2010-07-01

    Palladium sulphide (PdS) films have been prepared by direct sulphuration of 20 nm thick palladium films at different temperatures (200 C < T < 450 C). Sulphurated films exhibit an unique crystalline phase: PdS. Seebeck coefficient and electrical resistivity of these films are between -110 and -150 {mu}V/K and {proportional_to} 0.08 to 0.8 {omega}cm depending on the sulphuration temperature. Negative sign of Seebeck coefficient indicates an n type conduction in all films. Discussion is focused on the influence of atomic ratio between sulphur and palladium as well as impurities arising from the substrate on transport properties. (orig.)

  7. Synthesis of palladium nanoshell using a layer-by-layer technique

    Energy Technology Data Exchange (ETDEWEB)

    Ashayer, Roya [Kings College London, Department of Mechanical Engineering (United Kingdom); Green, Mark [Kings College London, Department of Physics (United Kingdom); Mannan, Samjid H., E-mail: samjid.mannan@kcl.ac.u [Kings College London, Department of Mechanical Engineering (United Kingdom)

    2010-05-15

    Complete palladium nanoshells were prepared by reducing palladium ions in a one-step reaction onto preformed silica cores of ca. 90 nm, which had been coated with successive layers of poly(diallyldimethyl ammonium chloride), poly(sodium styrenesulfonate) and finally poly(diallyldimethyl ammonium chloride) to reverse the zeta potential of the silica cores. This constitutes the first reported method for complete palladium nanoshell formation without the use of other metals as nucleation sites. The morphology of the nanoshell is of the rough discrete particle type rather than the smooth continuous type.

  8. Continuous palladium-based thin films for hydrogen detection

    Science.gov (United States)

    Corso, Alain J.; Angiola, Marco; Tessarolo, Enrico; Guidolin, Martino; Donazzan, Alberto; Martucci, Alessandro; Pelizzo, Maria G.

    2017-05-01

    Metallic films of palladium (Pd) and palladium-tin (Pd-Sn) have been deposited by evaporation technique. They were used as sensitive material for optical sensor by measuring the variation of absorbance. All samples were then oxidized by annealing at 500°C in low vacuum atmosphere. All the films were investigated by X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM) to observe the influence of the structure and morphology on the optical properties of the films, carrying useful information for the sensing properties of the different sensing materials. Furthermore, the sensing performances were tested by monitoring the variation on the optical absorbance induced during the absorption / desorption of hydrogen gas. While the use of Pd for gas sensing has been widely covered for electrical and SPR sensors, this work aims to extend our comprehension of the optical sensing behavior, especially in absorbance-mode, of the thin films of PdO, Pd-Sn and PdO-SnO2.

  9. Hydrogen sensor based on palladium-yttrium alloy nanosheet

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Boyi [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia); Zhu, Yong, E-mail: y.zhu@griffith.edu.au [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia); Chen, Youping; Song, Han; Huang, Pengcheng [School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 (China); Dao, Dzung Viet [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia)

    2017-06-15

    This paper presents a hydrogen sensor based on palladium-yttrium (Pd-Y) alloy nanosheet. Zigzag-shaped Pd-Y nanosheet with a thickness of 19.3 nm was deposited on a quartz substrate by using an ultrahigh-vacuum magnetron sputtering system and shadow mask. The atomic ratio of palladium to yttrium in the nanosheet was 0.92/0.08. The fabrication process was simple and low-cost, and the sensor can be mass-produced. The experimental results show the sensor has a superior sensitivity, reversibility, and reproducibility. The resistive-based hydrogen detection mechanism in this research is much simpler and more compact compared to the optical-based detection method. - Highlights: • Pd-Y sensing element was fabricated using a magnetron sputtering system and shadow mask. • The Pd-Y compound consisted of 92% Pd and 8% Y. • The fabrication process was simple, low-cost, and mass-production compatible. • The sensor showed superior sensitivity, reversibility, and reproducibility to hydrogen gas. • The device is more compact than the optical-based counterpart.

  10. Fast-neutron scattering from vibrational palladium nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.B. [Argonne National Lab., IL (United States)]|[Univ. of Arizona, Tucson, AZ (United States); Guenther, P.T. [Argonne National Lab., IL (United States)

    1993-10-01

    Neutron total cross sections of elemental palladium are measured from {approx}0.6--4.5 MeV. These results, combined with others previously reported from this laboratory, provide a detailed knowledge of the neutron total cross sections of palladium from {approx}0.1--20 MeV. Differential neutron elastic-scattering cross sections are measured from {approx}1.5--10 MeV in sufficient energy and angle detail to well define the energy-average behavior. Concurrently, neutron inelastic-scattering cross sections are measured from {approx}1.5--8 MeV. Inelastically-scattered neutron groups are observed corresponding to excitations of: 306 {+-} 14, 411 {+-} 47, {approx}494, 791 {+-} 20, 924 {+-} 20, 1,156 {+-} 24, 1,358 {+-} 35, 1,554 {+-} 47 and 1,706 {+-} 59 keV, with additional tentative groups at 1,938 and 2,059 keV. Particular attention is given to the inelastic excitation of the 2{sup +} yrast states of the even isotopes. This broad data base is examined in the context of optical-statistical and coupled-channels models. The resulting model parameters are consistent with systematic trends in this vibrational mass region previously noted at this laboratory, and provide a suitable vehicle for many applications.

  11. Palladium-functionalized Nanostructured Platforms for Enhanced Hydrogen Sensing

    Directory of Open Access Journals (Sweden)

    Ankur Gupta

    2016-06-01

    Full Text Available This paper reports on miniaturized hydrogen sensing platforms, exploring several means of fabricating nano‐ structured films and evaluating their sensing characteris‐ tics. Palladium-sputtered nanoporous organosilicate matrices are fabricated using the polymeric system [poly‐ methylsilsesquioxane (PMSSQ; polypropylene glycol (PPG; propylene glycol methyl ether acetate (PGMEA] followed by volatilization of the liquid phase, i.e., PGMEA and PPG at their boiling points. In order to provide greater adsorption/desorption sites for the test gas, ultra-dense ZnO nano-brushes with very high aspect ratios are suc‐ cessfully fabricated in the porous template. Thereafter, functionalization of ZnO is performed by sputter coating thin Pd films onto the ZnO surface. Intensive characteriza‐ tion for these nanostructures is performed using FESEM, EDAX, FTIR, TEM and AFM techniques. Comparison of all fabricated sensing platforms for hydrogen gas-dependent responses based on temperature, as well as test gas concentrations at various ppm levels, is performed. Palladium coating of ZnO nano-brushes renders this film highly selective to hydrogen and also improves its sensi‐ tivity by a factor of ~66% relative to the uncoated film. Sensitivity to hydrogen is found to be ~70% and a selectivity test is performed with CO2 and CH4, with sensitivities of 5% and 7%, respectively. Pd-functionalized ZnO nano-brushes display enhanced hydrogen response behaviour.

  12. Light-induced EMF in silver-palladium film resistors

    Science.gov (United States)

    Mikheev, G. M.; Zonov, R. G.; Aleksandrov, V. A.

    2010-07-01

    We have studied the generation of nanosecond emf pulses in silver-palladium film resistors under the action of radiation of a Q-switched laser. The samples were fabricated using the technology of thick film resistors on dielectric substrates, based on fusing a resistive paste that contains palladium, silver oxide, glass, and an organic binder into the substrate at 880 K. The amplitude of detected pulses exhibits linear growth with the power of incident laser radiation, depends on the angle of light incidence (vanishes at the normal incidence) onto the film and the angle of film rotation about the normal to its surface, and changes its sign with that of the incidence angle. The duration of the generated emf pulses is several times that of the incident laser pulses. The signal is not of a thermoelectric nature and can be related to the current generation by means of the surface photogalvanic effect and the photon quasi-momentum transfer to charge carriers during light absorption by the film material.

  13. Hydrogen response of porous palladium nano-films

    Science.gov (United States)

    Gupta, D.; Barman, P. B.; Hazra, S. K.

    2015-08-01

    Palladium nanoparticles were synthesized by reducing sodium tetrachloropalladate at 100°C using Ethylene Glycol as reducing agent. The nanoparticles were characterized by TEM (Transmission Electron Microscopy), and optical absorption spectroscopy. The average particle size (films were prepared by drying the nanoparticles precipitate on cleaned glass substrates. The high porosity of these films, as revealed by Atomic Force Microscopy (AFM) studies, made these films suitable for hydrogen sensor applications. The resistance of the films, measured by making silver paste contacts on the porous surface, changed upon exposure to 1000 ppm hydrogen in nitrogen. Optimum sensor response was obtained at 50°C, beyond which it deteriorated. The total response comprising of initial rise and subsequent fall in resistance, is due to the formation of Pd-hydrides (whose resistivity is higher relative to Pd), and closure of interparticle gaps due to lattice expansion of palladium, respectively. A detailed analysis of the results based on the sensing mechanism has been discussed in the paper.

  14. A new electrochemical sensor for the simultaneous determination of acetaminophen and codeine based on porous silicon/palladium nanostructure.

    Science.gov (United States)

    Ensafi, Ali A; Ahmadi, Najmeh; Rezaei, Behzad; Abarghoui, Mehdi Mokhtari

    2015-03-01

    A porous silicon/palladium nanostructure was prepared and used as a new electrode material for the simultaneous determination of acetaminophen (ACT) and codeine (COD). Palladium nanoparticles were assembled on porous silicon (PSi) microparticles by a simple redox reaction between the Pd precursor and PSi in an aqueous solution of hydrofluoric acid. This novel nanostructure was characterized by different spectroscopic and electrochemical techniques including scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, fourier transform infrared spectroscopy and cyclic voltammetry. The high electrochemical activity, fast electron transfer rate, high surface area and good antifouling properties of this nanostructure enhanced the oxidation peak currents and reduced the peak potentials of ACT and COD at the surface of the proposed sensor. Simultaneous determination of ACT and COD was explored using differential pulse voltammetry. A linear range of 1.0-700.0 µmol L(-1) was achieved for ACT and COD with detection limits of 0.4 and 0.3 µmol L(-1), respectively. Finally, the proposed method was used for the determination of ACT and COD in blood serum, urine and pharmaceutical compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. A simple and sensitive method for determination of taxifolin on palladium nanoparticles supported poly (diallyldimethylammonium chloride) functionalized graphene modified electrode.

    Science.gov (United States)

    Wang, Qinqin; Wang, Lu; Li, Gaiping; Ye, Baoxian

    2017-03-01

    Palladium nanoparticles with diameter of around 5-10nm supported on poly (diallyldimethylammonium chloride) (PDDA)-functionalized graphene composites were prepared by a simple chemical method. As-prepared nanocomposites were characterized by transmission electron microscopy (TEM), x-ray diffraction (XRD), ultraviolet-visible spectrophotometry (UV-vis) and electrochemical techniques, which were clearly demonstrated that palladium nanoparticles were uniformly dispersed on the graphene sheets. Based on the PDDA-Gr-Pd nanocomposites, a new voltammetric sensor was established and exhibited excellent electrocatalytic activity and fast electron transfer rate toward taxifolin. Under the optimal conditions, a lower detection limit of 1×10 -9 molL -1 (S/N=3) and a wide linear detection range from 4×10 -8 to 1×10 -6 molL -1 were achieved by square wave voltammetry (SWV). The proposed method was successfully applied for determination of taxifolin in fructus polygoni orientalis with well results. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Wet processing of palladium for use in the tritium facility at Westinghouse, Savannah River, SC. Preparation of palladium using the Mound Muddy Water process

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, D.P.; Zamzow, D.S.

    1998-11-10

    Palladium used at Savannah River for tritium storage is currently obtained from a commercial source. In order to better understand the processes involved in preparing this material, Savannah River is supporting investigations into the chemical reactions used to synthesize this material and into the conditions necessary to produce palladium powder that meets their specifications. This better understanding may help to guarantee a continued reliable source for this material in the future. As part of this evaluation, a work-for-others contract between Westinghouse Savannah River Company and the Ames Laboratory Metallurgy and Ceramics Program was initiated. During FY98, the process for producing palladium powder developed in 1986 by Dan Grove of Mound Applied Technologies (USDOE) was studied to understand the processing conditions that lead to changes in morphology in the final product. This report details the results of this study of the Mound Muddy Water process, along with the results of a round-robin analysis of well-characterized palladium samples that was performed by Savannah River and Ames Laboratory. The Mound Muddy Water process is comprised of three basic wet chemical processes, palladium dissolution, neutralization, and precipitation, with a number of filtration steps to remove unwanted impurity precipitates.

  17. Microwave activation of palladium nanoparticles for enhanced ethanol electrocatalytic oxidation reaction in alkaline medium

    CSIR Research Space (South Africa)

    Rohwer, MB

    2015-02-01

    Full Text Available gave higher electrochemical active surface area (EASA= 67 m(SUP2)g(SUP-1), aggregation/uniformity of dispersion, showed higher amount of the palladium oxides, and showed remarkable electrocatalytic behaviour towards ethanol oxidation reaction...

  18. Nano-palladium is a cellular catalyst for in vivo chemistry

    Science.gov (United States)

    Miller, Miles A.; Askevold, Bjorn; Mikula, Hannes; Kohler, Rainer H.; Pirovich, David; Weissleder, Ralph

    2017-07-01

    Palladium catalysts have been widely adopted for organic synthesis and diverse industrial applications given their efficacy and safety, yet their biological in vivo use has been limited to date. Here we show that nanoencapsulated palladium is an effective means to target and treat disease through in vivo catalysis. Palladium nanoparticles (Pd-NPs) were created by screening different Pd compounds and then encapsulating bis[tri(2-furyl)phosphine]palladium(II) dichloride in a biocompatible poly(lactic-co-glycolic acid)-b-polyethyleneglycol platform. Using mouse models of cancer, the NPs efficiently accumulated in tumours, where the Pd-NP activated different model prodrugs. Longitudinal studies confirmed that prodrug activation by Pd-NP inhibits tumour growth, extends survival in tumour-bearing mice and mitigates toxicity compared to standard doxorubicin formulations. Thus, here we demonstrate safe and efficacious in vivo catalytic activity of a Pd compound in mammals.

  19. Selective catalytic oxidations by palladium and manganese : Selectivity, reactivity and mechanistic studies

    NARCIS (Netherlands)

    Dong, Jiajia

    2015-01-01

    What is the difference between fire and life? Both are essentially oxidations with oxygen; the difference is selectivity and sustainability. In this dissertation the goal was primarily achieving control over oxidation chemistry to gain selectivity using environmentally friendly palladium and

  20. Methods of IR spectroscopy in monitoring of chemotherapy of oncological pathologies using palladium complexes

    Science.gov (United States)

    Tolstorozhev, G. B.; Bel'kov, M. V.; Skornyakov, I. V.; Pekhn'o, V. I.; Kozachkova, A. N.; Tsarik, N. V.; Kutsenko, I. P.; Sharykina, N. I.

    2014-11-01

    FTIR spectroscopy is used to study mammary-gland tissues of mice with a sarcoma tumor (strain 180). Spectral features that are typical of malignant tumors are revealed in the FTIR spectra in the sarcoma-tumor tissues. Tumor tissues are studied after treatment using coordination compounds based on palladium complexes with 3-amino-1-hydroxypropylidene-1,1-diphosphonic acid and zoledronic acid. A therapeutic effect is not revealed after treatment using palladium complex with 3-amino-1-hydroxypropylidene-1,1-diphosphonic acid. The suppression of tumor growth amounts to 59% when palladium complexes with zoledronic acid are used. Suppression of tumor growth is accompanied by variations in spectral characteristics. With respect to diagnostic features, the FTIR spectra of tumor tissues after treatment with the palladium complexes with zoledronic acid are similar to the FTIR spectra of tissues that are free of malignant tumors. Specific spectroscopic characteristics that make it possible to control the chemotherapy of oncological pathologies are determined.

  1. Complexation equilibria in tetrahydrofuran solutions of palladium(II) and lithium bromides

    Science.gov (United States)

    Putin, A. Yu.; Katsman, E. A.; Temkin, O. N.; Bruk, L. G.

    2017-04-01

    The solutions of palladium PdBr2 and lithium LiBr bromides in tetrahydrofuran (THF) at different concentrations were studied by UV-Vis spectroscopy. The data obtained were mathematically processed using various models. The best description was obtained with the model that includes the formation of four monomeric (PdBr+, PdBr2, PdBr 3 - , PdBr 4 2- ) and three dimeric (Pd2Br 2 2+ , Pd2Br4, Pd2Br 6 2- ) palladium complexes. The equilibrium constants of the monomer and dimer complexation stages and the extinction coefficients of the palladium complexes were calculated. The spectra of the individual monomer and dimer palladium complexes were calculated using this model.

  2. Palladium-Zeolite nanofiber as an effective recyclable catalyst membrane for water treatment.

    Science.gov (United States)

    Choi, Jungsu; Chan, Sophia; Yip, Garriott; Joo, Hyunjong; Yang, Heejae; Ko, Frank K

    2016-09-15

    Zeolite is an exciting natural material due to its unique capability of ammonium nitrogen (NH3N) adsorption in water. In this study, multifunctional hybrid composites of zeolite/palladium (Ze/Pd) on polymer nanofiber membranes were fabricated and explored for sustainable contaminant removal. SEM and XRD demonstrated that zeolite and palladium nanoparticles were uniformly distributed and deposited on the nanofibers. NH3N recovery rate was increased from 23 to 92% when palladium coated zeolite was embedded on the nanofiber. Multifunctional nanofibers of Ze/Pd membranes were able to adsorb NH3N on the zeolites placed on the surface of fibers and palladium catalysts were capable of selective oxidation of NH3N to N2 gas. The cycling of NH3N adsorption-oxidation, high flux, hydrophilicity, and flexibility of the membrane makes it a strong candidate for water treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Reductive dechlorination of 3,3',4,4'-tetrachlorobiphenyl (PCB77) using palladium or palladium/iron nanoparticles and assessment of the reduction in toxic potency in vascular endothelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Venkatachalam, Karthik [Department of Chemistry, University of Kentucky, Lexington, KY 40506 (United States); Arzuaga, Xabier [Molecular and Cell Nutrition Laboratory, College of Agriculture, University of Kentucky, KY 40506 (United States); Chopra, Nitin; Gavalas, Vasilis G. [Department of Chemistry, University of Kentucky, Lexington, KY 40506 (United States); Xu, Jian; Bhattacharyya, Dibakar [Department of Chemical Engineering, University of Kentucky, Lexington, KY 40506 (United States); Hennig, Bernhard [Molecular and Cell Nutrition Laboratory, College of Agriculture, University of Kentucky, KY 40506 (United States); Bachas, Leonidas G. [Department of Chemistry, University of Kentucky, Lexington, KY 40506 (United States)], E-mail: bachas@uky.edu

    2008-11-30

    Palladium-based nanoparticles immobilized in polymeric matrices were applied to the reductive dechlorination of 3,3',4,4'-tetrachlorobiphenyl (PCB77) at room temperature. Two different dechlorination platforms were evaluated using (1) Pd nanoparticles within conductive polypyrrole films; or (2) immobilized Fe/Pd nanoparticles within polyvinylidene fluoride microfiltration membranes. For the first approach, the polypyrrole film was electrochemically formed in the presence of perchlorate ions that were incorporated into the film to counter-balance the positive charges of the polypyrrole chain. The film was then incubated in a solution containing tetrachloropalladate ions, which were exchanged with the perchlorate ions within the film. During this exchange, reduction of tetrachloropalladate by polypyrrole occurred, which led to the formation of palladium nanoparticles within the film. For the second approach, the membrane-supported Fe/Pd nanoparticles were prepared in three steps: polymerization of acrylic acid in polyvinylidene fluoride microfiltration membrane pores was followed by ion exchange of Fe{sup 2+}, and then chemical reduction of the ferrous ions bound to the carboxylate groups. The membrane-supported iron nanoparticles were then soaked in a solution of tetrachloropalladate resulting in the deposition of Pd on the Fe surface. The nanoparticles prepared by both approaches were employed in the dechlorination of PCB77. The presence of hydrogen was required when the monometallic Pd nanoparticles were employed. The results indicate the removal of chlorine atoms from PCB77, which led to the formation of lower chlorinated intermediates and ultimately biphenyl. Toxicity associated with vascular dysfunction by PCB77 and biphenyl was compared using cultured endothelial cells. The data strongly suggest that the dechlorination system used in this study markedly reduced the proinflammatory activity of PCB77, a persistent organic pollutant.

  4. Sensing of aqueous fluoride anions by cationic stibine-palladium complexes.

    Science.gov (United States)

    Wade, Casey R; Ke, Iou-Sheng; Gabbaï, François P

    2012-01-09

    Turn on the lantern! The stibine donor ligand of a cationic palladium complex acts as a Lewis acid and reacts with a fluoride anion to afford the corresponding fluorostiboranyl-palladium species (see scheme). Bindung of the fluoride anion to the antimony center induces a change in denticity of the triphosphine unit and leads to a bright-orange trigonal-bipyramidal d(8) lantern complex. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Palladium - potassium humate coated by Polymetallic catalysts for the process of hydrogenation of nitrocompounds

    Directory of Open Access Journals (Sweden)

    E. Yermoldina

    2013-09-01

    Full Text Available Results of studies of humic substances in the quality of natural polymeric modifier for the coated palladium catalysts are presented in the paper. Synthesis of new catalysts based on palladium - potassium humate fixed on various inorganic carriers and their catalytic properties have been studied. The catalysts of 0,8% Pd - Potassium’s Humat(1%/B-94 and 0,8% Pd /Shungite 1% КОН are optimal.

  6. Enantioconvergent synthesis by sequential asymmetric Horner-Wadsworth-Emmons and palladium-catalyzed allylic substitution reactions

    DEFF Research Database (Denmark)

    Pedersen, Torben Møller; Hansen, E. Louise; Kane, John

    2001-01-01

    A new method for enantioconvergent synthesis has been developed. The strategy relies on the combination of an asymmetric Horner-Wadsworth-Emmons (HWE) reaction and a palladium-catalyzed allylic substitution. Different $alpha@-oxygen-substituted, racemic aldehydes were initially transformed...... by asymmetric HWE reactions into mixtures of two major $alpha@,$beta@-unsaturated esters, possessing opposite configurations at their allylic stereocenters as well as opposite alkene geometry. Subsequently, these isomeric mixtures of alkenes could be subjected to palladium-catalyzed allylic substitution...

  7. Review on Copper and Palladium Based Catalysts for Methanol Steam Reforming to Produce Hydrogen

    OpenAIRE

    Xinhai Xu; Kaipeng Shuai; Ben Xu

    2017-01-01

    Methanol steam reforming is a promising technology for producing hydrogen for onboard fuel cell applications. The methanol conversion rate and the contents of hydrogen, carbon monoxide and carbon dioxide in the reformate, significantly depend on the reforming catalyst. Copper-based catalysts and palladium-based catalysts can effectively convert methanol into hydrogen and carbon dioxide. Copper and palladium-based catalysts with different formulations and compositions have been thoroughly inve...

  8. Separation of carrier-free silver from neutron-irradiated palladium.

    Science.gov (United States)

    Lyle, S J; Maghzian, R

    1968-07-01

    The use of a chelate-forming ion-exchange resin for the separation of carrier-free silver-111 from neutron irradiated palladium is described. On décrit l'emploi d'une résine échangeuse d'ions formant des chélates pour la séparation de l'argent-111 exempt d'entraîneur du palladium irradié aux neutrons.

  9. Determination of palladium by flame photometry; Determinacion de paladio por fotometria de llama

    Energy Technology Data Exchange (ETDEWEB)

    Parallada Bellod, R.

    1964-07-01

    A study on the determination of palladium by lame photometry, fixing the most convent experimental conditions and using solvents to increase the emission of this elements is carried out. Among the organic solvents, acetone has been found the most efficient. The interferences produced by anions and cations have also been studied and an analytical method is related, in which lines of calibration of 0 to 100 ppm palladium re used. (Author) 7 refs.

  10. Thermodynamics for complex formation between palladium(ii) and oxalate.

    Science.gov (United States)

    Pilný, Radomír; Lubal, Přemysl; Elding, Lars I

    2014-08-28

    Complex formation between [Pd(H2O)4](2+) and oxalate (ox = C2O4(2-)) has been studied spectrophoto-metrically in aqueous solution at variable temperature, ionic strength and pH. Thermodynamic parameters at 298.2 K and 1.00 mol dm(-3) HClO4 ionic medium for the complex formation [Pd(H2O)4](2+) + H2ox ⇄ [Pd(H2O)2(ox)] + 2H3O(+) with equilibrium constant K1,H (in mol dm(-3)) are log10K1,H = 3.38 ± 0.08, ΔH = -33 ± 3 kJ mol(-1), and ΔS = -48 ± 11 J K(-1) mol(-1), as determined from spectrophotometric equilibrium titrations at 15.0, 20.0, 25.0 and 31.0 °C. Thermodynamic overall stability constants β (in (mol dm(-3))(-n), n = 1,2) for [Pd(H2O)2(ox)] and [Pd(ox)2](2-) at zero ionic strength and 298.2 K, defined as the equilibrium constants for the reaction Pd(2+) + nox(2-) ⇄ [Pd(ox)n](2-2n) (water molecules omitted) are log10β = 9.04 ± 0.06 and log10β = 13.1 ± 0.3, respectively, calculated by use of Specific Ion Interaction Theory from spectrophotometric titrations with initial hydrogen ion concentrations of 1.00, 0.100 and 0.0100 mol dm(-3) and ionic strengths of 1.00, 2.00 or 3.00 mol dm(-3). The values derived together with literature data give estimated overall stability constants for Pd(ii) compounds such as [Pd(en)(ox)] and cis-[Pd(NH3)2Cl2], some of them analogs to Pt(ii) complexes used in cancer treatment. The palladium oxalato complexes are significantly more stable than palladium(ii) complexes with monodentate O-bonding ligands. A comparison between several different palladium complexes shows that different parameters contribute to the stability variations observed. These are discussed together with the so-called chelate effect.

  11. Bimetallic redox synergy in oxidative palladium catalysis.

    Science.gov (United States)

    Powers, David C; Ritter, Tobias

    2012-06-19

    Polynuclear transition metal complexes, which are embedded in the active sites of many metalloenzymes, are responsible for effecting a diverse array of oxidation reactions in nature. The range of chemical transformations remains unparalleled in the laboratory. With few noteworthy exceptions, chemists have primarily focused on mononuclear transition metal complexes in developing homogeneous catalysis. Our group is interested in the development of carbon-heteroatom bond-forming reactions, with a particular focus on identifying reactions that can be applied to the synthesis of complex molecules. In this context, we have hypothesized that bimetallic redox chemistry, in which two metals participate synergistically, may lower the activation barriers to redox transformations relevant to catalysis. In this Account, we discuss redox chemistry of binuclear Pd complexes and examine the role of binuclear intermediates in Pd-catalyzed oxidation reactions. Stoichiometric organometallic studies of the oxidation of binuclear Pd(II) complexes to binuclear Pd(III) complexes and subsequent C-X reductive elimination from the resulting binuclear Pd(III) complexes have confirmed the viability of C-X bond-forming reactions mediated by binuclear Pd(III) complexes. Metal-metal bond formation, which proceeds concurrently with oxidation of binuclear Pd(II) complexes, can lower the activation barrier for oxidation. We also discuss experimental and theoretical work that suggests that C-X reductive elimination is also facilitated by redox cooperation of both metals during reductive elimination. The effect of ligand modification on the structure and reactivity of binuclear Pd(III) complexes will be presented in light of the impact that ligand structure can exert on the structure and reactivity of binuclear Pd(III) complexes. Historically, oxidation reactions similar to those discussed here have been proposed to proceed via mononuclear Pd(IV) intermediates, and the hypothesis of mononuclear Pd

  12. Recycling of a spent iron based catalyst for the complete oxidation of toluene: effect of palladium.

    Science.gov (United States)

    Kim, Sang Chai; Nah, Jae Woon

    2015-01-01

    Complete oxidation of volatile organic compound (toluene) was carried out to assess the property and activity of the palladium-spent iron based catalyst. The properties of the prepared catalysts were characterized by using the Brunauer-Emmett-Teller method and by conducting temperature-programmed reduction, X-ray diffraction, X-ray photoelectron spectroscopy and field emission transmission electron microscopy. The addition of palladium to the spent iron based catalyst pretreated with oxalic acid shifted the conversion curve for the total oxidation of toluene to lower temperature. An increase in the toluene conversion due to palladium was highly related to the easier lattice oxygen mobility of the catalysts. Instrumental analysis suggested the presence of a strong interaction between palladium and iron oxide species. Moreover, in the case of reducing the Pd/Fe catalyst with hydrogen, palladium accelerated the reducing iron oxides, subsequently decreasing the toluene conversion. As a result, the oxidation states of palladium and iron had an important effect on the catalytic activity.

  13. Preparation of Palladium-Impregnated Ceria by Metal Complex Decomposition for Methane Steam Reforming Catalysis

    Directory of Open Access Journals (Sweden)

    Worawat Wattanathana

    2017-01-01

    Full Text Available Palladium-impregnated ceria materials were successfully prepared via an integrated procedure between a metal complex decomposition method and a microwave-assisted wetness impregnation. Firstly, ceria (CeO2 powders were synthesized by thermal decomposition of cerium(III complexes prepared by using cerium(III nitrate or cerium(III chloride as a metal source to form a metal complex precursor with triethanolamine or benzoxazine dimer as an organic ligand. Palladium(II nitrate was consequently introduced to the preformed ceria materials using wetness impregnation while applying microwave irradiation to assist dispersion of the dopant. The palladium-impregnated ceria materials were obtained by calcination under reduced atmosphere of 10% H2 in He stream at 700°C for 2 h. Characterization of the palladium-impregnated ceria materials reveals the influences of the metal complex precursors on the properties of the obtained materials. Interestingly, the palladium-impregnated ceria prepared from the cerium(III-benzoxazine dimer complex revealed significantly higher BET specific surface area and higher content of the more active Pdδ+ (δ > 2 species than the materials prepared from cerium(III-triethanolamine complexes. Consequently, it exhibited the most efficient catalytic activity in the methane steam reforming reaction. By optimization of the metal complex precursors, characteristics of the obtained palladium-impregnated ceria catalysts can be modified and hence influence the catalytic activity.

  14. Palladium-catalyzed anti-Markovnikov oxidation of terminal alkenes.

    Science.gov (United States)

    Dong, Jia Jia; Browne, Wesley R; Feringa, Ben L

    2015-01-12

    The palladium-catalyzed oxidation of alkenes, the Wacker-Tsuji reaction, is undoubtedly a classic in organic synthesis and provides reliable access to methyl ketones from terminal alkenes under mild reaction conditions. Methods that switch the selectivity of the reaction to provide the aldehyde product are desirable because of the access they provide to a valuable functional group, however such methods are elusive. Herein we survey both the methods which have been developed recently in achieving such selectivity and discuss common features and mechanistic insight which offers promise in achieving the goal of a general method for anti-Markovnikov-selective olefin oxidations. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Ozone Sensing Based on Palladium Decorated Carbon Nanotubes

    Science.gov (United States)

    Colindres, Selene Capula; Aguir, Khalifa; Sodi, Felipe Cervantes; Vargas, Luis Villa; Moncayo Salazar, José A.; Febles, Vicente Garibay

    2014-01-01

    Multiwall carbon nanotubes (MWCNTs) were easily and efficiently decorated with Pd nanoparticles through a vapor-phase impregnation-decomposition method starting from palladium acetylacetonates. The sensor device consisted on a film of sensitive material (MWCNTs-Pd) deposited by drop coating on platinum interdigitated electrodes on a SiO2 substrate. The sensor exhibited a resistance change to ozone (O3) with a response time of 60 s at different temperatures and the capability of detecting concentrations up to 20 ppb. The sensor shows the best response when exposed to O3 at 120 °C. The device shows a very reproducible sensor performance, with high repeatability, full recovery and efficient response. PMID:24736133

  16. Formation of palladium(0) nanoparticles at microbial surfaces

    DEFF Research Database (Denmark)

    Bunge, Michael; Søbjerg, Lina S; Rotaru, Amelia-Elena

    2010-01-01

    The increasing demand and limited natural resources for industrially important platinum-group metal (PGM) catalysts render the recovery from secondary sources such as industrial waste economically interesting. In the process of palladium (Pd) recovery, microorganisms have revealed a strong...... potential. Hitherto, bacteria with the property of dissimilatory metal reduction have been in focus, although the biochemical reactions linking enzymatic Pd(II) reduction and Pd(0) deposition have not yet been identified. In this study we investigated Pd(II) reduction with formate as the electron donor......) nanoparticles were still deposited on autoclaved cells of C. necator that had no hydrogenase activity, suggesting a hydrogenase-independent formation mechanism. The catalytic properties of Pd(0) and bioPd(0) were determined by the amount of hydrogen released in a reaction with hypophosphite. Generally, bioPd(0...

  17. Green Synthesis, Characterization and Uses of Palladium/Platinum Nanoparticles

    Science.gov (United States)

    Siddiqi, Khwaja Salahuddin; Husen, Azamal

    2016-11-01

    Biogenic synthesis of palladium (Pd) and platinum (Pt) nanoparticles from plants and microbes has captured the attention of many researchers because it is economical, sustainable and eco-friendly. Plant and their parts are known to have various kinds of primary and secondary metabolites which reduce the metal salts to metal nanoparticles. Shape, size and stability of Pd and Pt nanoparticles are influenced by pH, temperature, incubation time and concentrations of plant extract and that of the metal salt. Pd and Pt nanoparticles are broadly used as catalyst, as drug, drug carrier and in cancer treatment. They have shown size- and shape-dependent specific and selective therapeutic properties. In this review, we have discussed the biogenic fabrication of Pd/Pt nanoparticles, their potential application as catalyst, medicine, biosensor, medical diagnostic and pharmaceuticals.

  18. Comparative Corrosion Behavior of Two Palladium Containing Titanium Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lian, T; Yashiki, T; Nakayama, T; Nakanishi, T; Rebak, R B

    2006-02-05

    The ASTM standard B 265 provides the requirements for the chemical composition of titanium (Ti) alloys. It is planned to use corrosion resistant and high strength titanium alloys to fabricate the drip shield at the proposed Yucca Mountain Repository. Titanium grade (Gr) 7 (R52400) and other Ti alloys are currently being characterized for this application. Ti Gr 7 contains 0.15% Palladium (Pd) to increase its corrosion performance. In this article we report results on the comparative short term corrosion behavior of Ti Gr 7 and a Ruthenium (Ru) containing alloy (Ti Gr 33). Ti Gr 33 also contains a small amount of Pd. Limited electrochemical testing such as polarization resistance and cyclic potentiodynamic curves showed that both alloys have a similar corrosion behavior in the tested environments.

  19. Circular photogalvanic effect observed in silver-palladium film resistors

    Science.gov (United States)

    Mikheev, G. M.; Aleksandrov, V. A.; Saushin, A. S.

    2011-06-01

    The surface circular photogalvanic effect (CPGE) at a laser wavelength of 1064 nm was observed for the first time in silver-palladium resistors fabricated by a thick-film technology. The CPGE response was detected using the electrodes oriented parallel to the radiation incidence plane, for the laser beam obliquely incident onto the sample surface. The coefficient of the pulsed laser radiation power conversion into light-induced emf (with the polarity depending on the sign of the circular polarization) amounted to about 80 mV/MW for film dimensions of 0.02 × 20 × 20 mm and a load resistance of 50 Ω. The maximum absolute value of the conversion coefficient was observed for the angles of light incidence of ±60°.

  20. H-point standard addition method--first derivative spectrophotometry for simultaneous determination of palladium and cobalt.

    Science.gov (United States)

    Eskandari, Habibollah

    2006-02-01

    H-point standard addition method (HPSAM) has been applied for simultaneous determination of palladium and cobalt in trace levels, using disodium 1-nitroso-2-naphthol-3, 6-disulphonate (nitroso-R salt) as a selective chromogenic reagent. Palladium and cobalt in the neutral pHs form red color complexes with nitroso-R in aqueous solutions and making spectrophotometric monitoring possible. Simultaneous determination of palladium and cobalt were performed by HPSAM--first derivative spectrophotometry. First derivative signals at the two pairs of wavelengths, 523 and 589 nm or 513 and 554 nm were monitored with the addition of standard solutions of palladium or cobalt, respectively. The method is able to accurately determine palladium/cobalt ratio 1:10 to 15:1 (wt/wt). Accuracy and reproducibility of the determination method on the various amounts of palladium and cobalt known were evaluated in their binary mixtures. To investigate selectivity of the method and to ensure that no serious interferences were observed the effects of diverse ions on the determination of palladium and cobalt were also studied. The recommended procedure was successfully applied to real and synthetic cobalt or palladium alloys, B-complex ampoules, a palladium-charcoal mixture and real water matrices.

  1. Kinetic and morphological studies of palladium oxidation in oxygen-methane mixtures

    Science.gov (United States)

    Han, Jinyi

    The oxidation of Pd single crystals: Pd(111), Pd(100) and Pd(110) was studied using Temperature Programmed Desorption (TPD), X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES), Low Electron Energy Diffraction (LEED) and Scanning Tunneling Microscopy (STM) as they were subjected to O2 in the pressure range between 1 and 150 Torr at temperatures 600-900 K. The oxygen species formed during oxidation, the oxygen uptake dependence on the sample history, the Pd single crystal surface morphology transformations, and the catalytic methane combustion over Pd single crystals were investigated in detail. The Pd single crystal oxidation proceeded through a three-step mechanism. Namely, (1) oxygen dissociatively adsorbed on Pd surface, forming chemisorbed oxygen and surface oxide; (2) atomic oxygen diffused through a thin surface oxide layer into Pd metal, forming near surface and bulk oxygen; (3) bulk PdO formed when a critical oxygen concentration was reached in the near surface region. The diffusion of oxygen through thin surface oxide layer into Pd metal decreased in the order: Pd(110)>Pd(100)>Pd(111). The oxygen diffusion coefficient was estimated to be around 10-16 cm2 s -1 at 600 K, with an activation energy of 80 kJ mol-1. Once bulk PdO was formed, the diffusion of oxygen through the bulk oxide layer was the rate-determining step for the palladium oxidation. The diffusion coefficient was equal to 10-18 cm2 s-1 at 600 K and the activation energy was approximately 120 kJ mol-1. The oxygen diffusion through thin surface oxide layer and bulk PdO followed the Mott-Cabrera parabolic diffusion law. The oxygen uptake on Pd single crystals depended on the sample history. The uptake amount increased with the population of the bulk oxygen species, which was achieved by high oxygen exposure at elevated temperatures, for example in 1 Torr O2 at above 820 K. Ar+ sputtering or annealing in vacuum at 1300 K depleted the bulk oxygen. The Pd single crystal surface

  2. Brushing-induced surface roughness of nickel-, palladium-, and gold-based dental casting alloys.

    Science.gov (United States)

    Wataha, John C; Lockwood, Petra E; Messer, Regina L W; Lewis, Jill B; Mettenburg, Donald J

    2008-06-01

    Alloys with high nickel content have been increasingly used for dental prostheses. These alloys have excellent hardness, elastic modulus, and strength, yet have high corrosion rates when exposed to chemical or physical forces that are common intraorally. The purpose of the current study was to measure the susceptibility of several types of nickel-based alloys to brushing abrasion relative to gold- and palladium-based alloys. Au-Pt, Au-Pd, Pd-Ag, Ni-Cr, and Ni-Cr-Be dental alloys were brushed with a toothbrush (Oral-B Soft) and toothpaste (Ultrabrite) in a linear brushing machine, then the surface roughness was measured by profilometry (R(a), R(v), R(p)). Specimens (n=4) were brushed for 48 hours in a saline solution (pH 7). The effect of brushing was determined using 2-sided t tests (alpha=.05), and roughness among alloys postbrushing was compared using 1-way ANOVA with Tukey post hoc analyses (alpha=.05). All polished alloy surfaces (before brushing) had roughnesses of 1 microm (R(a)). Ni-Cr alloys without Be had a postbrushing surface roughness of 0.25 microm (R(a)). Postbrushing roughness of all other alloys ranged from 0.1-0.25 microm (R(a)). R(v) and R(p) values behaved similarly to R(a) values for all alloys. Although they have many excellent mechanical properties, Ni-Cr-Be alloys may be prone to degradation from brushing.

  3. Conversion of hydrophilic SiOC nanofibrous membrane to robust hydrophobic materials by introducing palladium

    Science.gov (United States)

    Wu, Nan; Wan, Lynn Yuqin; Wang, Yingde; Ko, Frank

    2017-12-01

    Hydrophobic ceramic nanofibrous membranes have wide applications in the fields of high-temperature filters, oil/water separators, catalyst supports and membrane reactors, for their water repellency property, self-cleaning capability, good environmental stability and long life span. In this work, we fabricated an inherently hydrophobic ceramic nanofiber membrane without any surface modification through pyrolysis of electrospun polycarbosilane nanofibers. The hydrophobicity was introduced by the hierarchical microstructure formed on the surface of the nanofibers and the special surface composition by the addition of trace amounts of palladium. Furthermore, the flexible ceramic mats demonstrated robust chemical resistance properties with consistent hydrophobicity over the entire pH value range and effective water-in-oil emulsion separation performance. Interestingly, a highly cohesive force was found between water droplet and the ceramic membranes, suggesting their great potentials in micro-liquid transportation. This work provides a new route for adjusting the composition of ceramic surface and flexible, recyclable and multifunctional ceramic fibrous membranes for utilization in harsh environments.

  4. Palladium-Catalyzed Anti-Markovnikov Oxidation of Allylic Amides to Protected β-Amino Aldehydes.

    Science.gov (United States)

    Dong, Jia Jia; Harvey, Emma C; Fañanás-Mastral, Martín; Browne, Wesley R; Feringa, Ben L

    2014-12-10

    A general method for the preparation of N-protected β-amino aldehydes from allylic amines or linear allylic alcohols is described. Here the Pd(II)-catalyzed oxidation of N-protected allylic amines with benzoquinone is achieved in tBuOH under ambient conditions with excellent selectivity toward the anti-Markovnikov aldehyde products and full retention of configuration at the allylic carbon. The method shows a wide substrate scope and is tolerant of a range of protecting groups. Furthermore, β-amino aldehydes can be obtained directly from protected allylic alcohols via palladium-catalyzed autotandem reactions, and the application of this method to the synthesis of β-peptide aldehydes is described. From a mechanistic perspective, we demonstrate that tBuOH acts as a nucleophile in the reaction and that the initially formed tert-butyl ether undergoes spontaneous loss of isobutene to yield the aldehyde product. Furthermore, tBuOH can be used stoichiometrically, thereby broadening the solvent scope of the reaction. Primary and secondary alcohols do not undergo elimination, allowing the isolation of acetals, which subsequently can be hydrolyzed to their corresponding aldehyde products.

  5. High efficiency resonance ionization of palladium with Ti:sapphire lasers

    Science.gov (United States)

    Kron, T.; Liu, Y.; Richter, S.; Schneider, F.; Wendt, K.

    2016-09-01

    This work presents the development and testing of highly efficient excitation schemes for resonance ionization of palladium. To achieve the highest ionization efficiencies, a high-power, high repetition rate Ti:sapphire laser system was used and 2-step, 3-step and 4-step schemes were investigated and compared. Starting from different excited steps, the frequencies of the final ionization steps were tuned across the full accessible spectral range of the laser system, revealing several autoionizing Rydberg series, which converge towards the energetically higher lying state 4{{{d}}}9{}2{{{D}}}3/2 of the Pd+ ion ground state configuration. Through proper choice of these excitation steps, we developed a highly efficient, fully resonant 3-step excitation scheme, which lead to overall efficiencies of 54.3(1.4) % and 59.7(2.1) %, measured at two independent mass separator setups. To our knowledge, these are presently the highest efficiency values ever achieved with a resonance ionization laser ion source.

  6. Assembling strategy to synthesize palladium modified kaolin nanocomposites with different morphologies

    Science.gov (United States)

    Li, Xiaoyu; Ouyang, Jing; Zhou, Yonghua; Yang, Huaming

    2015-09-01

    Nanocomposites of aluminosilicate minerals, kaolins (kaolinite and halloysite) with natural different morphologies assembling with palladium (Pd) nanoparticles have been successfully synthesized through strong electrostatic adsorption and chemical bonding after surface modification with 3-aminopropyl triethoxysilane (APTES). Meanwhile, the influence of different morphologies supports on catalytic hydrogenation properties was explored. The surface concentration of amino groups on the kaolins was related to the morphology and surface nature. Electronmicroscopy revealed that the monodisperse Pd nanoparticles were uniformly deposited onto the surface of kaolins, ranging in diameter from 0.5 nm to 5.5 nm. The functional groups could not only improve the dispersion of kaolins with different morphologies in solution, but also enhance the interaction between Pd precursors and kaolins, thus preventing small Pd nanoparticles from agglomerating and leading to high activity for the catalytic hydrogenation of styrene. Pd-FK@APTES was more active compared to other samples. Selecting the kaolin morphology with a different surface nature allows the selective surface modification of a larger fraction of the reactive facets on which the active sites can be enriched and tuned. This desirable surface coordination of catalytically active atoms could substantially improve catalytic activity.

  7. Palladium nanoparticles deposited on graphene and its electrochemical performance for glucose sensing

    Science.gov (United States)

    Mijowska, Ewa; Onyszko, Magdalena; Urbas, Karolina; Aleksandrzak, Malgorzata; Shi, Xiaoze; Moszyński, Dariusz; Penkala, Krzysztof; Podolski, Jacek; El Fray, Mirosława

    2015-11-01

    This paper reports on the fabrication and characterization of glucose oxidase (GOx) immobilized onto a glassy carbon electrode (GCE) modified with reduced graphene oxide/palladium nanocomposite (RGO-Pd). Characterization tools showed well dispersed uniform Pd nanoparticles on a partly reduced graphene oxide surface. Cyclic voltammetry demonstrated successful immobilization of GOx on RGO-Pd modified GCE (GCE-RGO-Pd) using covalent bonding of GOx with RGO-Pd (RGO-Pd-GOx). Therefore, it was used as an electrochemical biosensor of glucose. RGO-Pd-GOx exhibited good electrocatalysis toward glucose in different glucose concentrations (from 2 to 10 mM, which includes the blood glucose levels of both normal and diabetic persons) with O2 saturated phosphate buffer solution (PBS) at pH 7.4. The system showed a linear increase in current at potential -0.085 V in the concentration range examined, with a correlation coefficient of 0.996. The sensitivity of the biosensor was 41.3 μA cm-2 mM-1, suggesting that RGO-Pd-GOx-modified GCE could be a potential candidate as a glucose sensor.

  8. Physical properties of new cerium palladium phosphide with C6Cr23-type structure

    Directory of Open Access Journals (Sweden)

    T. Abe

    2014-01-01

    Full Text Available We have found that a cerium palladium phosphide crystallizes into a C6Cr23-type structure with atomic disorder. Prepared polycrystalline samples show a homogeneity range in the ternary Ce–Pd–P phase diagram. The physical properties of the highest-quality sample of Ce2.4Pd20.7P5.9 were investigated by measuring the magnetization, electrical resistivity and specific heat. No pronounced phase transition was observed down to 0.5 K. The Kondo screening of localized 4f electrons in metallic Ce2.4Pd20.7P5.9 appears to be weaker than that in the isostructural compounds of Ce3Pd20Si6 and Ce3Pd20Ge6. By a comparative study of Ce2.4Pd20.7P5.9 and Ce3Pd20X6 (X = Si, Ge, the competition between the Kondo temperature and ordering temperatures including the quadrupolar ordering temperature is briefly discussed.

  9. A fumonisins immunosensor based on polyanilino-carbon nanotubes doped with palladium telluride quantum dots.

    Science.gov (United States)

    Masikini, Milua; Mailu, Stephen N; Tsegaye, Abebaw; Njomo, Njagi; Molapo, Kerileng M; Ikpo, Chinwe O; Sunday, Christopher Edozie; Rassie, Candice; Wilson, Lindsay; Baker, Priscilla G L; Iwuoha, Emmanuel I

    2014-12-30

    An impedimetric immunosensor for fumonisins was developed based on poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes doped with palladium telluride quantum dots onto a glassy carbon surface. The composite was assembled by a layer-by-layer method to form a multilayer film of quantum dots (QDs) and poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes (PDMA-MWCNT). Preparation of the electrochemical immunosensor for fumonisins involved drop-coating of fumonisins antibody onto the composite modified glassy carbon electrode. The electrochemical impedance spectroscopy response of the FB1 immunosensor (GCE/PT-PDMA-MWCNT/anti-Fms-BSA) gave a linear range of 7 to 49 ng L-1 and the corresponding sensitivity and detection limits were 0.0162 kΩ L ng-1 and 0.46 pg L-1, respectively, hence the limit of detection of the GCE/PT-PDMA-MWCNT immunosensor for fumonisins in corn certified material was calculated to be 0.014 and 0.011 ppm for FB1, and FB2 and FB3, respectively. These results are lower than those obtained by ELISA, a provisional maximum tolerable daily intake (PMTDI) for fumonisins (the sum of FB1, FB2, and FB3) established by the Joint FAO/WHO expert committee on food additives and contaminants of 2 μg kg-1 and the maximum level recommended by the U.S. Food and Drug Administration (FDA) for protection of human consumption (2-4 mg L-1).

  10. Observations of 'uphill' diffusion of hydrogen in palladium and nickel membranes by an electrochemical permeation method

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, Y. (Dept. of Materials Science and Engineering, Nagasaki Univ. (Japan)); Tanaka, H. (Dept. of Materials Science and Engineering, Nagasaki Univ. (Japan)); Lewis, F.A. (School of Chemistry, Queen' s Univ. of Belfast, Northern Ireland (United Kingdom)); Tong, X.Q. (School of Chemistry, Queen' s Univ. of Belfast, Northern Ireland (United Kingdom))

    1993-01-01

    The 'uphill' diffusion of hydrogen during permeation through flat sheets of palladium and nickel has been studied by an electrochemical permeation method at 303 K. For both annealed and as cold rolled Pd samples, uphill diffusion effects during both hydrogen absorption and desorption have been observed with initial hydrogen contents ranging from about H/Pd = 0.01 up to H/Pd = 0.25-0.3. The non-Fickian permeation fluxes have been associated with lattice volume differences across the ([alpha] + [beta])/[beta] and ([alpha] + [beta])/[alpha] interfaces. Influences of magnitudes of galvanostatic currents and membrane thickness were examined. In similar studies with nickel membranes analogous uphill effects were observed. (orig.)

  11. Palladium-catalyzed direct arylation of azine and azole N-oxides: reaction development, scope and applications in synthesis.

    Science.gov (United States)

    Campeau, Louis-Charles; Stuart, David R; Leclerc, Jean-Philippe; Bertrand-Laperle, Mégan; Villemure, Elisia; Sun, Ho-Yan; Lasserre, Sandrine; Guimond, Nicolas; Lecavallier, Melanie; Fagnou, Keith

    2009-03-11

    Palladium-catalyzed direct arylation reactions are described with a broad range of azine and azole N-oxides. In addition to aspects of functional group compatibility, issues of regioselectivity have been explored when nonsymmetrical azine N-oxides are used. In these cases, both the choice of ligand and the nature of the azine substituents play important roles in determining the regioisomeric distribution. When azole N-oxides are employed, preferential reaction is observed for arylation at C2 which occurs under very mild conditions. Subsequent reactions are observed to occur at C5 followed by arylation at C4. The potential utility of this methodology is illustrated by its use in the synthesis of a potent sodium channel inhibitor 1 and a Tie2 Tyrosine Kinase inhibitor 2.

  12. Selective Reductive Elimination at Alkyl Palladium(IV) by Dissociative Ligand Ionization: Catalytic C(sp3)-H Amination to Azetidines.

    Science.gov (United States)

    Nappi, Manuel; He, Chuan; Whitehurst, William G; Chappell, Ben G N; Gaunt, Matthew J

    2018-01-30

    A palladium(II)-catalyzed γ-C-H amination of cyclic alkyl amines to deliver highly substituted azetidines is reported. The use of a benziodoxole tosylate oxidant in combination with AgOAc was found to be crucial for controlling a selective reductive elimination pathway to the azetidines. The process is tolerant of a range of functional groups, including structural features derived from chiral α-amino alcohols, and leads to the diastereoselective formation of enantiopure azetidines. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Formation and growth of palladium nanoparticles inside porous poly(4-vinyl-pyridine) monitored by operando techniques : The role of different reducing agents

    NARCIS (Netherlands)

    Lazzarini, Andrea; Groppo, Elena; Agostini, Giovanni; Borfecchia, Elisa; Giannici, Francesco; Portale, Giuseppe; Longo, Alessandro; Pellegrini, Riccardo; Lamberti, Carlo

    2017-01-01

    In this work we followed the formation of palladium nanoparticles, starting from palladium (II) acetate precursor, inside a poly(4-vinylpyridine-co-divinylbenzene) polymer in presence of different reducing agents. The formation and growth of palladium nanoparticles in presence of H-2 was followed as

  14. Self-assembly of palladium nanoparticles on functional TiO{sub 2} nanotubes for a nonenzymatic glucose sensor

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xianlan [School of Science, Honghe University, Mengzi, Yunnan 661100 (China); College of Chemistry, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Li, Gang; Zhang, Guowei [School of Science, Honghe University, Mengzi, Yunnan 661100 (China); Hou, Keyu [College of Chemistry, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Pan, Haibo, E-mail: hbpan@fzu.edu.cn [College of Chemistry, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Du, Min [Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China)

    2016-05-01

    Polydiallyldimethylammonium chloride, PDDA, was used as a stabilizer and linker for functionalized TiO{sub 2} nanotubes (TiO{sub 2} NTs). Self-assembled process with palladium nanoparticles (NPs) was successfully synthesized and used for the oxidation of glucose on glassy carbon electrodes. Based on the voltammetric and amperometric results, Pd NPs efficiently catalyzed the oxidation of glucose at − 0.05 V in the presence of 0.1 M NaCl and showed excellent resistance toward interference poisoning from such interfering species as ascorbic acid, uric acid and urea. To further increase sensitivity, the Pd NPs-PDDA-TiO{sub 2} NTs/GCE was electrochemically treated with H{sub 2}SO{sub 4} and NaOH, the glucose oxidation current was magnified 2.5 times than that before pretreatments due to greatly enhancing the electron transport property of the sensor based on the increased defect sites and surface oxide species. In view of the physiological level of glucose, the wide linear concentration range of glucose (4 × 10{sup −7}–8 × 10{sup −4} M) with a detection limit of 8 × 10{sup −8} M (S/N = 3) was obviously good enough for clinical application. - Highlights: • PDDA was used as a stabilizer and linker for functionalized TiO{sub 2} nanotubes. • Self-assembled process with palladium nanoparticles was synthesized. • After treated both H{sub 2}SO{sub 4} and NaOH, the glucose response was magnified to 2.5 times. • The wide linear concentration range of glucose was obtained with a limit of 8 × 10{sup −8} M.

  15. Ageing of palladium tritide: mechanical characterization, helium state and modelling; Vieillissement du tritiure de palladium: caracterisation mecanique, etat de l'helium et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Segard, M.

    2010-11-29

    Palladium is commonly used for the storage of tritium (the hydrogen radioactive isotope), since it forms a low-equilibrium-pressure and reversible tritide. Tritium decay into helium-3 is responsible for the ageing of the tritide, leading to the apparition of helium-3 bubbles for instance. Both experimental and theoretical aspects of this phenomenon are studied here.Previous works on ageing modelling led to two main models, dealing with:- Helium-3 bubbles nucleation (using a cellular automaton), - Bubbles growth (using continuum mechanics).These models were quite efficient, but their use was limited by the lack of input data and fitting experimental parameters.To get through these limitations, this work has consisted in studying the most relevant experimental data to improve the modelling of the palladium tritide ageing.The first part of this work was focused on the assessment of the mechanical properties of the palladium tritide (yield strength, ultimate strength, mechanical behaviour). They were deduced from the in situ tensile tests performed on palladium hydride and deuteride. In the second part, ageing characterization was undertaken, mainly focusing on: - Bubbles observations in palladium tritide using transmission electron microscopy, - Internal bubble pressure measurements using nuclear magnetic resonance, - Macroscopic swelling measurements using pycno-metry.The present work has led to significant progress in ageing understanding and has brought very valuable improvements to the modelling of such a phenomenon. (author) [French] Le palladium est couramment utilise pour le stockage du tritium, isotope radioactif de l'hydrogEne, car il forme un tritiure reversible, A basse pression d'equilibre. La decroissance du tritium en helium-3 provoque un vieillissement du tritiure, caracterise notamment par l'apparition de bulles d'helium-3, qui est etudie ici. De precedents travaux de modelisation du vieillissement avaient abouti a la creation de

  16. Controlled immobilization of palladium nanoparticles in two different fluorinated polymeric aggregate cores and their application in catalysis

    DEFF Research Database (Denmark)

    Kijima, Tetsushi; Javakhishvili, Irakli; Jankova Atanasova, Katja

    2012-01-01

    Fluoroalkyl end-capped betaine-type cooligomeric nanocomposites-immobilized palladium nanoparticles were prepared by the reactions of palladium chloride with sodium acetate in the presence of sodium chloride and the corresponding fluorinated cooligomers. Outer blocks of poly(2,3,4,5,6-pentafluoro......Fluoroalkyl end-capped betaine-type cooligomeric nanocomposites-immobilized palladium nanoparticles were prepared by the reactions of palladium chloride with sodium acetate in the presence of sodium chloride and the corresponding fluorinated cooligomers. Outer blocks of poly(2......,3,4,5,6-pentafluorostyrene)-containing ABA-triblock copolymeric nanocomposites-immobilized palladium nanoparticles were prepared by the use of the corresponding block copolymers under similar conditions. TEM images showed that palladium nanoparticles can be immobilized outside the fluorinated cooligomeric nanocomposite...... cores; in contrast, palladium nanoparticles can be effectively immobilized inside these fluorinated ABA-triblock copolymeric nanocomposite cores. Thus, these two different fluorinated copolymers enabled the controlled immobilization of palladium nanoparticles in the fluorinated nanocomposite cores...

  17. Palladium on Carbon-Catalyzed Suzuki-Miyaura Coupling Reaction Using an Efficient and Continuous Flow System

    Directory of Open Access Journals (Sweden)

    Tomohiro Hattori

    2015-01-01

    Full Text Available The continuous flow Suzuki-Miyaura reaction between various haloarenes and arylboronic acids was successfully achieved within only ca. 20 s during the single-pass through a cartridge filled with palladium on carbon (Pd/C. No palladium leaching was observed in the collected reaction solution by atomic absorption spectrometry (detection limit: 1 ppm.

  18. Corrosion behavior of palladium-silver-copper alloys in model saliva.

    Science.gov (United States)

    Joska, Ludek; Poddana, Marcela; Leitner, Jindrich

    2008-08-01

    Palladium-silver system alloyed with other metals represents one of possible material choices in prosthetics. Its corrosion properties are influenced by minority components added in order to obtain the properties required for stomatological purposes. The objective of this work was to ascertain the influence of copper on the corrosion mechanism of palladium-silver alloys. Corrosion properties of four palladium-silver-copper alloys were compared with the behavior of the palladium-silver binary system. Standard electrochemical measurements in a model saliva solution were complemented with an XPS analysis of the specimens surface. Experimental data were compared with the results of thermodynamic analysis. The foregoing study revealed formation of a saline layer of insoluble silver compounds as the dominant feature of the corrosion mechanism in a binary system. This process is suppressed in ternary alloys where electrochemical reactions of copper take place on the alloy-electrolyte phase boundary leading to the formation of a layer based on copper oxides. The alloying of the palladium-silver binary system with copper results in an important change in the corrosion behavior of ternary alloys. A change in the mechanism of interaction with the environment leads to susceptibility to non-uniform corrosion.

  19. Selective recovery of palladium from waste printed circuit boards by a novel non-acid process.

    Science.gov (United States)

    Zhang, Zhiyuan; Zhang, Fu-Shen

    2014-08-30

    An environmental benign, non-acid process was successfully developed for selective recovery of palladium from waste printed circuit boards (PCBs). In the process, palladium was firstly enriched during copper recovery procedure and dissolved in a special solution made of CuSO4 and NaCl. The dissolved palladium was then extracted by diisoamyl sulfide (S201). It was found that 99.4% of Pd(II) could be extracted from the solution under the optimum conditions (10% S201, A/O ratio 5 and 2min extraction). In the whole extraction process, the influence of base metals was negligible due to the relatively weak nucleophilic substitution of S201 with base metal irons and the strong steric hindrance of S201 molecular. Around 99.5% of the extracted Pd(II) could be stripped from S201/dodecane with 0.1mol/L NH3 after a two-stage stripping at A/O ratio of 1. The total recovery percentage of palladium was 96.9% during the dissolution-extraction-stripping process. Therefore, this study established a benign and effective process for selective recovery of palladium from waste printed circuit boards. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Palladium-Catalyzed Cross-Coupling Reactions of Perfluoro Organic Compounds

    Directory of Open Access Journals (Sweden)

    Masato Ohashi

    2014-09-01

    Full Text Available In this review, we summarize our recent development of palladium(0-catalyzed cross-coupling reactions of perfluoro organic compounds with organometallic reagents. The oxidative addition of a C–F bond of tetrafluoroethylene (TFE to palladium(0 was promoted by the addition of lithium iodide, affording a trifluorovinyl palladium(II iodide. Based on this finding, the first palladium-catalyzed cross-coupling reaction of TFE with diarylzinc was developed in the presence of lithium iodide, affording α,β,β-trifluorostyrene derivatives in excellent yield. This coupling reaction was expanded to the novel Pd(0/PR3-catalyzed cross-coupling reaction of TFE with arylboronates. In this reaction, the trifluorovinyl palladium(II fluoride was a key reaction intermediate that required neither an extraneous base to enhance the reactivity of organoboronates nor a Lewis acid additive to promote the oxidative addition of a C–F bond. In addition, our strategy utilizing the synergetic effect of Pd(0 and lithium iodide could be applied to the C–F bond cleavage of unreactive hexafluorobenzene (C6F6, leading to the first Pd(0-catalyzed cross-coupling reaction of C6F6 with diarylzinc compounds.

  1. Synthesis of palladium nanoparticles using poly aniline reduction as Pd Cl{sub 2}; Sintese de nanoparticulas de paladio utilizando polianilina como redutor de PdCl{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Everton Carlos; Oliveira, Maria Auxiliadora Silva de, E-mail: evertonquimica@gmail.com [Instituto Tecnologico da Aeronautica - ITA, Divisao de Engenharia Mecanica e Aeronautica, Centro de Referencia em Turbinas a Gas, Sao Jose dos Campos, SP (Brazil)

    2011-07-01

    The development of hybrid composites has grown in recent years due to their wide potential range of application. This paper describes the formation of palladium nanoparticles by reducing Pd (II) ions to Pd (0) with polyaniline emeraldine base (EB). The reduction of Pd{sup 2+} on the surface of polyaniline was examined by X-ray diffraction (XRD) and the morphology of the Pd particles was studied by scanning electron microscopy (SEM). Through the results of XRD and using the Scherrer's formula, it was possible to get the diameter of Pd particles that was close to 13 nm. SEM results showed white inclusions which were ascribed to cluster formation of palladium nanoparticles in polyaniline. (author)

  2. Synthesis of palladium nanoparticle modified reduced graphene oxide and multi-walled carbon nanotube hybrid structures for electrochemical applications

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jie, E-mail: hujie@tyut.edu.cn [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); Zhao, Zhenting; Zhang, Jun; Li, Gang; Li, Pengwei; Zhang, Wendong [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); Lian, Kun, E-mail: liankun@tyut.edu.cn [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); School of Nano-Science and Nano-Engineering, Suzhou & Collaborative Innovation Center of Suzhou Nano Science and Technology, Xi' an Jiaotong University, Xi' an, 710049 (China); Center for Advanced Microstructures and Devices, Louisiana State University, LA, 70806 (United States)

    2017-02-28

    Graphical abstract: A sensitive hydrazine electrochemical sensor was fabricated by using palladium (Pd) nanoparticle functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotube (MWCNTs) hybrid structures (Pd/rGO-MWCNTs). - Highlights: • rGO-MWCNTs hybrid structures and Pd nanoparticles are prepared using electrochemical methods. • rGO-MWCNTs hybrid films are used as supports and co-catalysts for Pd nanoparticles. • The Pd/rGO-MWCNTs hybrid structure based sensor shows an ultra-high sensitivity of 7.09 μA μM{sup −1} cm{sup −2} and a low detection limit of 0.15 μM. • The proposed electrochemical sensor exhibits excellent selectivity. - Abstract: In this work, palladium (Pd) nanoparticles functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) hybrid structures (Pd/rGO-MWCNTs) were successfully prepared by a combination of electrochemical reduction with electrodeposition method. The morphology, structure, and composition of the Pd/rGO-MWCNTs hybrid were characterized by scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy. The as-synthesized hybrid structures were modified on the glassy carbon electrode (GCE) and further utilized for hydrazine sensing. Electrochemical impedance spectroscopic, cyclic voltammetry and single-potential amperometry experiments were carried out on Pd/rGO-MWCNTs hybrid structures to investigate the interface properties and sensing performance. The measured results demonstrate that the fabricated Pd/rGO-MWCNTs/GCE sensor show a high sensitivity of 7.09 μA μM{sup −1} cm{sup −2} in a large concentration range of 1.0 to 1100 μM and a low detection limit of 0.15 μM. Moreover, the as-prepared sensor exhibits good selectivity and stability for the determination of hydrazine under interference conditions.

  3. Green Chemistry Approach for Synthesis of Effective Anticancer Palladium Nanoparticles

    Directory of Open Access Journals (Sweden)

    Sangiliyandi Gurunathan

    2015-12-01

    Full Text Available The purpose of this study was to design and synthesize Palladium nanoparticles (PdNPs using an environmentally friendly approach and evaluate the in vitro efficacy of PdNPs in human ovarian cancer A2780 cells. Ultraviolet-Visible (UV-Vis spectroscopy was used to monitor the conversion of Pd(II ions to Pd(0NPs. X-ray diffraction (XRD revealed the crystallinity of the as-synthesized PdNPs and Fourier transform infrared spectroscopy (FTIR further confirmed the role of the leaf extract of Evolvulus alsinoides as a reducing and stabilizing agent for the synthesis of PdNPs. Dynamic light scattering (DLS and transmission electron microscopy (TEM showed that the average size of the NPs was 5 nm. After a 24-h exposure to PdNPs, cell viability and light microscopy assays revealed the dose-dependent toxicity of the PdNPs. Furthermore, the dose-dependent cytotoxicity of the PdNPs was confirmed by lactate dehydrogenase (LDH, increased reactive oxygen species (ROS generation, activation of PdNPs-induced autophagy, impairment of mitochondrial membrane potential (MMP, enhanced caspase-3 activity, and detection of TUNEL-positive cells. Our study demonstrates a single, simple, dependable and green approach for the synthesis of PdNPs using leaf extracts of Evolvulus alsinoides. Furthermore, the in vitro efficacy of PdNPs in human ovarian cancer cells suggests that it could be an effective therapeutic agent for cancer therapy.

  4. Allergic contact granuloma due to palladium following ear piercing.

    Science.gov (United States)

    Goossens, An; De Swerdt, Ann; De Coninck, Karen; Snauwaert, Johan Ernest; Dedeurwaerder, Marleen; De Bonte, Marc

    2006-12-01

    Two cases of sarcoidal-type allergic contact granuloma due to metals in ear piercing are presented, the first to palladium (Pd) only, and the second to Pd and possibly also to other metals. Both the patients developed papulonodular lesions at the helices following ear piercing, which after 3-4 weeks, became more granulomatous and very resistant to treatment. Indeed, repeated intralesional injections with corticosteroids produced only a temporary regression of the lesions. Biopsies from the persistent granulomatous lesions from the helices in both the patients and the positive test to Pd in case 2, 3 weeks after the patch-testing procedure, demonstrated epithelioid granulomas, with some multinucleate histiocytes surrounded by a lymphocytic-histiocytic infiltrate. Areas of fibrinoid necrosis were found in both the helix biopsies. An infectious pathology was excluded. Patch testing showed a strong positive reaction to Pd only in case 1 and to Pd and nickel in case 2. Chemical analysis of the earring of patient 1 confirmed the presence of Pd; however, analysis of the earrings of the second patient did not show the presence of Pd, but showed the presence of nickel and copper. Both the clinical and histological findings concur with some rarely reported similar observations in the literature.

  5. Green Chemistry Approach for Synthesis of Effective Anticancer Palladium Nanoparticles.

    Science.gov (United States)

    Gurunathan, Sangiliyandi; Kim, EunSu; Han, Jae Woong; Park, Jung Hyun; Kim, Jin-Hoi

    2015-12-15

    The purpose of this study was to design and synthesize Palladium nanoparticles (PdNPs) using an environmentally friendly approach and evaluate the in vitro efficacy of PdNPs in human ovarian cancer A2780 cells. Ultraviolet-Visible (UV-Vis) spectroscopy was used to monitor the conversion of Pd(II) ions to Pd(0)NPs. X-ray diffraction (XRD) revealed the crystallinity of the as-synthesized PdNPs and Fourier transform infrared spectroscopy (FTIR) further confirmed the role of the leaf extract of Evolvulus alsinoides as a reducing and stabilizing agent for the synthesis of PdNPs. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) showed that the average size of the NPs was 5 nm. After a 24-h exposure to PdNPs, cell viability and light microscopy assays revealed the dose-dependent toxicity of the PdNPs. Furthermore, the dose-dependent cytotoxicity of the PdNPs was confirmed by lactate dehydrogenase (LDH), increased reactive oxygen species (ROS) generation, activation of PdNPs-induced autophagy, impairment of mitochondrial membrane potential (MMP), enhanced caspase-3 activity, and detection of TUNEL-positive cells. Our study demonstrates a single, simple, dependable and green approach for the synthesis of PdNPs using leaf extracts of Evolvulus alsinoides. Furthermore, the in vitro efficacy of PdNPs in human ovarian cancer cells suggests that it could be an effective therapeutic agent for cancer therapy.

  6. Synthesis, crystal structure and applications of palladium thiosalicylate complexes

    Directory of Open Access Journals (Sweden)

    S.B. Moosun

    2017-05-01

    Full Text Available Three palladium thiosalicylate complexes [Pd(tb(bipy]·3H2O (1, [Pd2(tb2(bipy2]·(dtdb2 (2 and [Pd2(tb2(phen2]·dtdb·H2O (3 (bipy = bipyridine; phen = phenanthroline were prepared from the reaction of PdCl2(CH3CN2 with dithiosalicylic acid (dtdb which underwent cleavage to form thiobenzoate anion (tb in DMF/MeOH. Square planar geometries of the complexes with a N2SO coordination type were proposed on the basis of single crystal X-ray structural study. The presence of trapped and uncoordinated dtdb was observed in complexes 2 and 3. Complexes 1–3 were evaluated as catalysts for Heck coupling reactions of methyl acrylate with iodobenzene, and showed moderate activities at a very low catalyst loading. Complex 1 was found to inhibit the growth of bacteria and scavenge free radicals efficiently.

  7. Biotemplated Palladium Catalysts Can Be Stabilized on Different Support Materials

    KAUST Repository

    Yates, Matthew D.

    2014-07-30

    © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Sustainably biotemplated palladium catalysts generated on different carbon-based support materials are examined for durability under electrochemical (oxidative) and mechanical-stress conditions. Biotemplated catalysts on carbon paper under both stresses retain 95% (at 0.6V) of the initial catalytic activity as opposed to 70% for carbon cloth and 60% for graphite. Graphite electrodes retain 95% of initial catalytic activity under a single stress. Using electrodeposited polyaniline (PANI) and polydimethylsiloxane binder increases the current density after the stress tests by 22%, as opposed to a 30% decrease for Nafion. PANI-coated electrodes retain more activity than carbon-paper electrodes under elevated mechanical (94 versus 70%) or increased oxidative (175 versus 62%) stress. Biotemplated catalytic electrodes may be useful alternatives to synthetically produce catalysts for some electrochemical applications. Sustainable electrode fabrication: The biotemplated synthesis of catalytic porous electrodes is a sustainable process and, according to the results of durability tests under electrochemical and mechanical stress, these electrodes (e.g. the Pd/carbon paper electrode shown in the picture) are durable enough to replace catalytic electrodes based on synthetic materials in certain applications.

  8. High Hydrogen Loading of Thin Palladium Wires Through

    CERN Document Server

    Celani, F; Marini, P; Di Stefano, V; Nakamura, M; Pace, S; Vecchione, A; Mancini, A; Tripodi, P; Di Gioacchino, D

    2000-01-01

    A new protocol for the electrolytic loading of hydrogen (H) in thin palladium (Pd) wires has been developed. In order to increase the cathodic overvoltage, which is known to be the main parameter capable to enhance the electrolytic $9 H loading of Pd, the catalytic action of the Pd surface versus H-H recombination has been strongly reduced by precipitation of a thin layer of alkaline-earth carbonates on the cathode. A set of electrolytes has been employed, $9 containing small amounts of hydrochloric or sulphuric acid and strontium or calcium ions. The H loading has been continuously evaluated through ac measurements of the Pd wire resistance. Uncommonly low resistivity values, leading to $9 an estimate of exceptionally high H loading, have been observed. Evidence of the existence of a new phase in the very high H content region of the Pd-H system has been inferred on the basis of the determination of the temperature $9 coefficient of the electrical resistivity. For this purpose a thin layer of Hg was galvanic...

  9. Novel antitrypanosomal agents based on palladium nitrofurylthiosemicarbazone complexes: DNA and redox metabolism as potential therapeutic targets.

    Science.gov (United States)

    Otero, Lucía; Vieites, Marisol; Boiani, Lucía; Denicola, Ana; Rigol, Carolina; Opazo, Lucía; Olea-Azar, Claudio; Maya, Juan Diego; Morello, Antonio; Krauth-Siegel, R Luise; Piro, Oscar E; Castellano, Eduardo; González, Mercedes; Gambino, Dinorah; Cerecetto, Hugo

    2006-06-01

    In the search for new therapeutic tools against American Trypanosomiasis palladium complexes with bioactive nitrofuran-containing thiosemicarbazones as ligands were obtained. Sixteen novel palladium (II) complexes with the formulas [PdCl2(HL)] and [Pd(L)2] were synthesized, and the crystal structure of [Pd(5-nitrofuryl-3-acroleine thiosemicarbazone)2] x 3DMSO was solved by X-ray diffraction methods. Most complexes showed higher in vitro growth inhibition activity against Trypanosoma cruzi than the standard drug Nifurtimox. In most cases, the activity of the ligand was maintained or even increased as a result of palladium complexation. In addition, the complexes' mode of antitrypanosomal action was investigated. Although the complexes showed strong DNA binding, all data strongly suggest that the main trypanocidal mechanism of action is the production of oxidative stress as a result of their bioreduction and extensive redox cycling. Moreover, the complexes were found to be irreversible inhibitors of trypanothione reductase.

  10. Novel macroporous palladium cation crosslinked chitosan membranes for heterogeneous catalysis application.

    Science.gov (United States)

    Zeng, Minfeng; Yuan, Xia; Yang, Zhen; Qi, Chenze

    2014-07-01

    A novel palladium supported on chitosan porous membrane heterogeneous catalyst has been prepared by freeze-drying of Pd(2+)-crosslinked chitosan gel solution. The prepared membrane catalyst has three-dimensional porous structure (porosity: >70%). The crosslinking effects of Pd(2+) to chitosan were good for the improvement of the mechanical properties and thermal stabilities. Pd(2+) cations have been shown not only as the crosslinker, but also as the catalytic active sites. The reductive palladium species of the recycled membrane catalysts was found in the nanometer scale (20-40nm). Excellent cross-coupling yields were achieved using as low as 0.12mol% palladium catalyst loading for the Heck-type reaction of aromatic halides with acrylates. The catalyst could be recycled six times without obvious decreased conversion. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Interaction between Palladium Nanoparticles and Surface-Modified Carbon Nanotubes: Role of Surface Functionalities

    DEFF Research Database (Denmark)

    Zhang, Bingsen; Shao, Lidong; Zhang, Wei

    2014-01-01

    degrees C. We focus on probing the effects of oxygen and nitrogen-containing functional groups on supported palladium nanoparticles (NPs) in the model catalytic system. The stability of palladium NPs supported on CNTs depends strongly on the surface properties of CNTs. Moreover, the oxygen-containing......It is crucial to accurately describe the interaction between the surface functionality and the supported metal catalyst because it directly determines the activity and selectivity of a catalytic reaction. It is, however, challenging with a metal-carbon catalytic system owing to the ultrafine...... feature, instability, and subtle response of the components upon application of an external field. Herein, we use insitu TEM, electron energy loss spectroscopy, and X-ray photoelectron spectroscopy techniques to record the interaction in palladium on carbon nanotubes (CNTs) from room temperature to 600...

  12. Hydrogen gas sensing with networks of ultra-small palladium nanowires formed on filtration membranes.

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, X. Q.; Latimer, M. L.; Xiao, Z. L.; Panuganti, S.; Welp, U.; Kwok, W. K.; Xu, T. (Materials Science Division); (Northern Illinois Univ.)

    2010-11-29

    Hydrogen sensors based on single Pd nanowires show promising results in speed, sensitivity, and ultralow power consumption. The utilization of single Pd nanowires, however, face challenges in nanofabrication, manipulation, and achieving ultrasmall transverse dimensions. We report on hydrogen sensors that take advantage of single palladium nanowires in high speed and sensitivity and that can be fabricated conveniently. The sensors are based on networks of ultrasmall (<10 nm) palladium nanowires deposited onto commercially available filtration membranes. We investigated the sensitivities and response times of these sensors as a function of the thickness of the nanowires and also compared them with a continuous reference film. The superior performance of the ultrasmall Pd nanowire network based sensors demonstrates the novelty of our fabrication approach, which can be directly applied to palladium alloy and other hydrogen sensing materials.

  13. Palladium nanoparticles in ionic liquids: reusable catalysts for aerobic oxidation of alcohols

    Science.gov (United States)

    Mondal, Arijit; Das, Amit; Adhikary, Bibhutosh; Mukherjee, Deb Kumar

    2014-04-01

    The search for more efficient catalytic systems that might combine the advantages of both homogenous (catalyst modulation) and heterogenous catalysis (catalyst recycling) is still the challenge of modern chemistry. With the advent of nanochemistry, it has been possible to prepare soluble analogues of heterogenous catalysts. These nanoparticles are generally stabilized against aggregation into larger less active particles by electrostatic or steric protection. In the present case, we demonstrate the use of room temperature ionic liquids (ILs) as effective agents of dispersion of palladium nanoparticles (prepared from palladium chloride with 5 ± 0.5 nm size distribution) that are recyclable catalysts for aerobic oxidation of alcohols under mild conditions. The particles suspended in ILs show no metal agglomeration or loss of catalytic activity even on prolonged use. An attempt has been made to elucidate the reaction mechanism of aerobic alcohol oxidation using a soluble palladium catalyst.

  14. Mechanical and Electrical Properties of Palladium-Coated Copper Wires with Flash Gold

    Science.gov (United States)

    Chang, Chia-Yun; Hung, Fei-Yi; Lui, Truan-Sheng

    2017-07-01

    Palladium-coated copper wire with flash gold (PCA) is a fine wire with an oxidation resistance layer. A new sulfidation test has been assessed in this work, confirming that PCA wires show better sulfidation corrosion resistance than either palladium-coated or bare copper wires. The sulfided surface of PCA was analyzed, along with its bonding strength and electrical properties. The metallurgic mechanism for formation of free air balls during the electric flame-off (EFO) process was identified. The flash gold layer of PCA wires can improve certain shortcomings, including: (1) efficiently promoting sulfidation corrosion resistance, (2) solving the problem of palladium segregation during the EFO process, (3) reducing the starting voltage, and (4) stabilizing the electrical resistivity of the bonding interface.

  15. A steric tethering approach enables palladium-catalysed C-H activation of primary amino alcohols

    Science.gov (United States)

    Calleja, Jonas; Pla, Daniel; Gorman, Timothy W.; Domingo, Victoriano; Haffemayer, Benjamin; Gaunt, Matthew J.

    2015-12-01

    Aliphatic primary amines are a class of chemical feedstock essential to the synthesis of higher-order nitrogen-containing molecules, commonly found in biologically active compounds and pharmaceutical agents. New methods for the construction of complex amines remain a continuous challenge to synthetic chemists. Here, we outline a general palladium-catalysed strategy for the functionalization of aliphatic C-H bonds within amino alcohols, an important class of small molecule. Central to this strategy is the temporary conversion of catalytically incompatible primary amino alcohols into hindered secondary amines that are capable of undergoing a sterically promoted palladium-catalysed C-H activation. Furthermore, a hydrogen bond between amine and catalyst intensifies interactions around the palladium and orients the aliphatic amine substituents in an ideal geometry for C-H activation. This catalytic method directly transforms simple, easily accessible amines into highly substituted, functionally concentrated and structurally diverse products, and can streamline the synthesis of biologically important amine-containing molecules.

  16. Watermelon rind-mediated green synthesis of noble palladium nanoparticles: catalytic application

    Science.gov (United States)

    Lakshmipathy, R.; Palakshi Reddy, B.; Sarada, N. C.; Chidambaram, K.; Khadeer Pasha, Sk.

    2015-02-01

    The present study reports the feasibility of synthesis of palladium nanoparticles (Pd NPs) by watermelon rind. The aqueous extract prepared from watermelon rind, an agro waste, was evaluated as capping and reducing agent for biosynthesis of palladium nanoparticles. The formation of Pd NPs was visually monitored with change in color from pale yellow to dark brown and later monitored with UV-Vis spectroscopy. The synthesized Pd NPs were further characterized by XRD, FTIR, DLS, AFM and TEM techniques. The synthesized Pd NPs were employed in Suzuki coupling reaction as catalyst. The results reveal that watermelon rind, an agro waste, is capable of synthesizing spherical-shaped Pd NPs with catalytic activity.

  17. Development of palladium-based nanocatalysts on carbon support for oxygen reduction reaction

    Science.gov (United States)

    Arroyo Ramirez, Lisandra

    Direct methanol fuel cell (DMFC) promises to be a power source for space application, transportation and portable devices. However, platinum catalysts, the methanol crossover and the sluggish kinetics of the oxygen reduction reaction (ORR) limit their commercialization. DMFC has the challenge to find a catalyst with high methanol tolerance and simple synthesis methodology. We proposed the development of palladium-based nanostructures on carbon supports as electrocatalyst for the oxygen reduction reaction. The working hypothesis is that the use of different methodologies and carbon supports will lead the formation of different palladium catalytic nanostructures with high methanol tolerance. A new single source approach was used to synthesize Pd-Co nanostructures on a highly ordered pyrolytic graphite (HOPG) surface using a bimetallic molecular precursor. Then, synthesis of palladium and palladium-cobalt nanoparticles on Vulcan XC-72R by chemical and thermal reduction using organometallic complexes as precursors was done. The palladium thin films and nanoshells were synthesized on HOPG and carbon cloth using sputtering deposition and electrospinning techniques. The morphology and composition were characterized by surface analysis techniques, such as: atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscope with energy-dispersive X-ray fluorescence spectroscopy (SEM/EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), among others. ORR electrocatalytic activity and methanol tolerance was determined for the Pd/C, Pd2Co/C and PdCo 2/C catalysts. The rotating ring-disk electrode technique was used to determine the ORR mechanism and kinetics. Pd2Co nanorings were formed on a HOPG surface by self-assembly with humidity control. Also, a single precursor was used for the synthesis of palladium-cobalt nanocatalysts on carbon supports by thermal reduction with ORR electrocatalytic activity and higher methanol

  18. High temperature silver-palladium-copper oxide air braze filler metal

    Science.gov (United States)

    Darsell, Jens Tommy

    The Ag-CuO system is currently being investigated as the basis for an air braze filler metal alloy to be used in SOFC components. The system is of interest because unlike most braze alloys, it is capable of wetting a variety of ceramic materials while being applied in an air. This thesis work examined modification of Ag-CuO filler metal system by alloying with palladium to increase the use temperature of the resulting air braze alloy. Thermal analysis was performed to track changes in the solidus and liquidus temperatures for these alloys and determine equilibrium phase present as a function of temperature and composition. Sessile drop experiments were performed to investigate the effect of palladium addition on braze wetability. The influence of copper-oxide and palladium contents on brazed joint strength was characterized by a combination of four-point bend testing and fractography. From combined thermal analysis and quenched data it was found that both the liquidus and solidus increase with increasing palladium content, and the silver-rich miscibility gap boundary could be shifted by the addition of palladium. This was employed as a tool to study the effects of two-liquid phase formation on wetting behavior. In addition, a mass loss likely attributable to silver volatilization is observed in the Pd-modified filler metals when heated over ˜1100°C. As volatilization should be avoided, the ternary alloys should be limited to 15mol% Pd. It was found by sessile drop wetting experiments that there is a definitive change in wetting behavior that corresponds directly to the miscibility gap boundary for the Pd-Ag-CuO system. The first order transition tracks with changes in the miscibility gap boundary that can be induced by increasing palladium content. This is the first experimental evidence of critical point wetting behavior reported for a metal-oxide system and further confirms that critical point wetting theory is universal. Four-point bend testing and

  19. Palladium-catalyzed migratory insertion of isocyanides: an emerging platform in cross-coupling chemistry.

    Science.gov (United States)

    Vlaar, Tjøstil; Ruijter, Eelco; Maes, Bert U W; Orru, Romano V A

    2013-07-08

    Isocyanides have been important building blocks in organic synthesis since the discovery of the Ugi reaction and related isocyanide-based multicomponent reactions. In the past decade isocyanides have found a new application as versatile C1 building blocks in palladium catalysis. Palladium-catalyzed reactions involving isocyanide insertion offer a vast potential for the synthesis of nitrogen-containing fine chemicals. This Minireview discusses all the achievements in this emerging field. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Préparation et caractérisation de catalyseurs au palladium supporté ...

    African Journals Online (AJOL)

    Les catalyseurs bimétalliques supportés sur alumine et silice palladium-or et palladium-cuivre avec des teneurs Pd-Au et Pd-Cu variant entre 0,85 à 1,42%Pd- 0,14 à 0,29%Au et 0,85 à 1,42% Pd- 0,21 à 0,28%Cu respectivement à partir des sels précurseurs de Pd(NH3)4(NO3)2, tétrachloraurate d'hydrogène, HAuCl4, ...

  1. 2,3-diaminopyridine functionalized reduced graphene oxide-supported palladium nanoparticles with high activity for electrocatalytic oxygen reduction reaction

    Science.gov (United States)

    Yasmin, Sabina; Joo, Yuri; Jeon, Seungwon

    2017-06-01

    The electrochemical deposition of Pd nanoparticles (Pd NPs) on 2,3 diamino pyridine functionalized reduced graphene oxide (2,3 DAP-rGO/Pd) has been investigated for the oxygen reduction reaction (ORR) in alkaline media. First, 2,3 diaminopyridine functionalized graphene oxide (2,3 DAP-rGO) has been synthesized via simple hydrothermal method. Then, palladium is directly incorporated into the 2,3 DAP-rGO by electrochemical deposition method to generate 2,3 DAP-rGO/Pd composites. The as-prepared material 2,3 DAP-rGO/Pd has been characterized by various instrumental methods. The morphological analysis shows the cluster-like Pd nanoparticles are dispersed onto the 2,3 diamino pyridine functionalized reduced graphene oxide (2,3 DAP-rGO). The electrocatalytic activities have been verified using cyclic voltammetry (CV) and hydrodynamic voltammetry and chronoamperometry techniques in 0.1 M KOH electrolyte. The as-synthesized 2,3 DAP-rGO/Pd shows higher catalytic activity toward ORR with more positive onset potential and cathodic current density, superior methanol/ethanol tolerance and excellent stability in alkaline medium. It is also noteworthy that the 2,3 DAP-rGO/Pd exhibits a four-electron transfer pathway for ORR with lower H2O2 yield.

  2. Thermal Neutron Capture Cross Sections of the PalladiumIsotopes

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, R.B.; Krticka, M.; McNabb, D.P.; Sleaford, B.; Agvaanluvsan, U.; Belgya, T.; Revay, Zs.

    2006-07-17

    Precise gamma-ray thermal neutron capture cross sectionshave been measured at the Budapest Reactor for all elements withZ=1-83,92 except for He and Pm. These measurements and additional datafrom the literature been compiled to generate the Evaluated Gamma-rayActivation File (EGAF), which is disseminated by LBNL and the IAEA. Thesedata are nearly complete for most isotopes with Z<20 so the totalradiative thermal neutron capture cross sections can be determineddirectly from the decay scheme. For light isotopes agreement with therecommended values is generally satisfactory although large discrepanciesexist for 11B, 12,13C, 15N, 28,30Si, 34S, 37Cl, and 40,41K. Neutroncapture decay data for heavier isotopes are typically incomplete due tothe contribution of unresolved continuum transitions so only partialradiative thermal neutron capture cross sections can be determined. Thecontribution of the continuum to theneutron capture decay scheme arisesfrom a large number of unresolved levels and transitions and can becalculated by assuming that the fluctuations in level densities andtransition probabilities are statistical. We have calculated thecontinuum contribution to neutron capture decay for the palladiumisotopes with the Monte Carlo code DICEBOX. These calculations werenormalized to the experimental cross sections deexciting low excitationlevels to determine the total radiative thermal neutron capture crosssection. The resulting palladium cross sections values were determinedwith a precision comparable to the recommended values even when only onegamma-ray cross section was measured. The calculated and experimentallevel feedings could also be compared to determine spin and parityassignments for low-lying levels.

  3. High Performance Palladium Supported on Nanoporous Carbon under Anhydrous Condition

    Science.gov (United States)

    Yang, Zehui; Ling, Ying; Zhang, Yunfeng; Xu, Guodong

    2016-11-01

    Due to the high cost of polymer electrolyte fuel cells (PEFCs), replacing platinum (Pt) with some inexpensive metal was carried out. Here, we deposited palladium nanoparticles (Pd-NPs) on nanoporous carbon (NC) after wrapping by poly[2,2‧-(2,6-pyridine)-5,5‧-bibenzimidazole] (PyPBI) doped with phosphoric acid (PA) and the Pd-NPs size was successfully controlled by varying the weight ratio between Pd precursor and carbon support doped with PA. The membrane electrode assembly (MEA) fabricated from the optimized electrocatalyst with 0.05 mgPd cm-2 for both anode and cathode sides showed a power density of 76 mW cm-2 under 120 °C without any humidification, which was comparable to the commercial CB/Pt, 89 mW cm-2 with 0.45 mgPt cm-2 loaded in both anode and cathode. Meanwhile, the power density of hybrid MEA with 0.45 mgPt cm-2 in cathode and 0.05 mgPd cm-2 in anode reached 188 mW cm-2. The high performance of the Pt-free electrocatalyst was attributed to the porous structure enhancing the gas diffusion and the PyPBI-PA facilitating the proton conductivity in catalyst layer. Meanwhile, the durability of Pd electrocatalyst was enhanced by coating with acidic polymer. The newly fabricated Pt-free electrocatalyst is extremely promising for reducing the cost in the high-temperature PEFCs.

  4. Enhancing the performance of single-chambered microbial fuel cell using manganese/palladium and zirconium/palladium composite cathode catalysts.

    Science.gov (United States)

    Jadhav, Dipak A; Deshpande, Parag A; Ghangrekar, Makarand M

    2017-08-01

    Application of ZrO2, MnO2, palladium, palladium-substituted-zirconium oxide (Zr0.98Pd0.02O2) and palladium-substituted-manganese oxide (Mn0.98Pd0.02O2) cathode catalysts in a single-chambered microbial fuel cell (MFC) was explored. The highest power generation (1.28W/m3) was achieved in MFC with Mn0.98Pd0.02O2 catalyst, which was higher than that with MnO2 (0.58W/m3) alone; whereas, MFC having Zr0.98Pd0.02O2 catalyzed cathode and non-catalyzed cathode produced powers of 1.02 and 0.23W/m3, respectively. Also, low-cost zirconium-palladium-composite showed better catalytic activity and capacitance over ZrO2 with 20A/m3 current production and demonstrated its suitability for MFC applications. Cyclic voltammetry analyses showed higher well-defined redox peaks in composite catalysts (Mn/Zr-Pd-C) over other catalyzed MFCs containing MnO2 or ZrO2. Electrochemical behaviour of composite catalysts on cathode showed higher availability of adsorption sites for oxygen reduction and, hence, enhanced the rate of cathodic reactions. Thus, Mn/Zr-Pd-C-based composite catalysts exhibited superior cathodic performance and could be proposed as alternatives to costly Pd-catalyst for field applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Palladium uptake by Pisum sativum: partitioning and effects on growth and reproduction.

    Science.gov (United States)

    Ronchini, Matteo; Cherchi, Laura; Cantamessa, Simone; Lanfranchi, Marco; Vianelli, Alberto; Gerola, Paolo; Berta, Graziella; Fumagalli, Alessandro

    2015-05-01

    Environmental palladium levels are increasing because of anthropogenic activities. The considerable mobility of the metal, due to solubilisation phenomena, and its known bioavailability may indicate interactions with higher organisms. The aim of the study was to determine the Pd uptake and distribution in the various organs of the higher plant Pisum sativum and the metal-induced effects on its growth and reproduction. P. sativum was grown in vermiculite with a modified Hoagland's solution of nutrients in the presence of Pd at concentrations ranging 0.10-25 mg/L. After 8-10 weeks in a controlled environment room, plants were harvested and dissected to isolate the roots, stems, leaves, pods and peas. The samples were analysed for Pd content using AAS and SEM-EDX. P. sativum absorbed Pd, supplied as K₂PdCl₄, beginning at seed germination and continuing throughout its life. Minimal doses (0.10-1.0 mg Pd/L) severely inhibited pea reproductive processes while showing a peculiar hormetic effect on root development. Pd concentrations ≥1 mg/L induced developmental delay, with late growth resumption, increased leaf biomass (up to 25%) and a 15-20% reduction of root mass. Unsuccessful repeated blossoming efforts led to misshapen pods and no seed production. Photosynthesis was also disrupted. The absorbed Pd (ca. 0.5 % of the supplied metal) was primarily fixed in the root, specifically in the cortex, reaching concentrations up to 200 μg/g. The metal moved through the stem (up to 1 μg/g) to the leaves (2 μg/g) and pods (0.3 μg/g). The presence of Pd in the pea fruits, together with established evidence of environmental Pd accumulation and bioavailability, suggests possible contamination of food plants and propagation in the food chain and must be the cause for concern.

  6. Synthesis and properties of palladium nanoparticles by pulsed laser ablation in liquid

    Energy Technology Data Exchange (ETDEWEB)

    Mendivil, M.I. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León 66450 (Mexico); Krishnan, B. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León 66450 (Mexico); CIIDIT – Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico); Castillo, G.A. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León 66450 (Mexico); Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León 66450 (Mexico); CIIDIT – Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico)

    2015-09-01

    Highlights: • Pd nanoparticle colloids were synthesized using PLAL technique. • Characterized by TEM, XPS and UV–vis spectroscopy. • Average size distribution was affected by different liquid media. • Laser post-irradiation was effective to regain optical properties. • Ultrasonic treatment helped to regain the optical properties. - Abstract: Pulsed laser ablation in liquid (PLAL) as a prominent technique for nanofabrication was employed to synthesize palladium (Pd) nanoparticles in different liquids. The synthesis of Pd nanoparticles was developed using a pulsed Nd:YAG laser with its fundamental wavelength output of 1064 nm (10 Hz, 10 ns) in a range of energy fluence (40.5–8 J/cm{sup 2}). Pure Pd metal target was immersed in distilled water, methanol–water mixture (1:1) and sodium dodecyl sulfate (SDS) to study the effect of the nature of the liquid media. Laser post-irradiation and ultrasonic treatments were applied to the precipitated colloidal solution to investigate their effects on the re-dispersion and stability. The mean size, size distributions, shape, elemental composition, optical properties and stability of nanoparticles synthesized by PLAL were examined by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV–vis absorption spectroscopy. TEM characterizations showed smaller nanoparticles in methanol–water mixture in comparison with the other liquids. Spherical morphology was observed for Pd nanoparticles synthesized in distilled water and methanol–water mixture. In the case of SDS, spherical nanoparticles embedded on the surfactant were observed. The effect of energy fluence was different for each liquid media. Laser post-irradiation and ultrasonic agitation worked as efficient methods to re-disperse the precipitates of NPs and to recover their optical properties.

  7. A Fumonisins Immunosensor Based on Polyanilino-Carbon Nanotubes Doped with Palladium Telluride Quantum Dots

    Directory of Open Access Journals (Sweden)

    Milua Masikini

    2014-12-01

    Full Text Available An impedimetric immunosensor for fumonisins was developed based on poly(2,5-dimethoxyaniline-multi-wall carbon nanotubes doped with palladium telluride quantum dots onto a glassy carbon surface. The composite was assembled by a layer-by-layer method to form a multilayer film of quantum dots (QDs and poly(2,5-dimethoxyaniline-multi-wall carbon nanotubes (PDMA-MWCNT. Preparation of the electrochemical immunosensor for fumonisins involved drop-coating of fumonisins antibody onto the composite modified glassy carbon electrode. The electrochemical impedance spectroscopy response of the FB1 immunosensor (GCE/PT-PDMA-MWCNT/anti-Fms-BSA gave a linear range of 7 to 49 ng L−1 and the corresponding sensitivity and detection limits were 0.0162 kΩ L ng−1 and 0.46 pg L−1, respectively, hence the limit of detection of the GCE/PT-PDMA-MWCNT immunosensor for fumonisins in corn certified material was calculated to be 0.014 and 0.011 ppm for FB1, and FB2 and FB3, respectively. These results are lower than those obtained by ELISA, a provisional maximum tolerable daily intake (PMTDI for fumonisins (the sum of FB1, FB2, and FB3 established by the Joint FAO/WHO expert committee on food additives and contaminants of 2 μg kg−1 and the maximum level recommended by the U.S. Food and Drug Administration (FDA for protection of human consumption (2–4 mg L−1.

  8. One pot synthesis of diarylfurans from aryl esters and PhI(OAc)2 via palladium-associated iodonium ylides.

    Science.gov (United States)

    Bao, Yong-Sheng; Agula, Bao; Zhaorigetu, Bao; Jia, Meilin; Baiyin, Menghe

    2015-04-14

    The example of palladium-catalyzed intermolecular cyclization for the synthesis of various diarylfurans in which one of the aromatic rings originates from the phenolic part of the starting ester and the other one from PhI(OAc)2 has been reported. The reaction is carried out through two steps: the rearrangement of palladium-associated iodonium ylides to form o-iodo diaryl ether and then palladium catalyzed intramolecular direct arylation. This reaction can tolerate a variety of functional groups and is alternative or complementary to the previous methods for the synthesis of diarylfurans.

  9. Determination of platinum and palladium in environmental samples by graphite furnace atomic absorption spectrometry after separation on dithizone sorbent.

    Science.gov (United States)

    Chwastowska, J; Skwara, W; Sterlińska, E; Pszonicki, L

    2004-09-08

    A graphite furnace atomic absorption method of platinum and palladium determination after their separation from environmental samples has been presented. The samples were digested by aqua regia and the analyte elements were separated on the dithizone sorbent. The procedure of sorbent preparation was described and their properties were established. Two various procedures of elution by thiourea and concentrated nitric acid were described and discussed. The low limit of detection was established as 1ngg(-1) for platinum and 0.2ngg(-1) for palladium. There was also investigated the behaviour of platinum and palladium introduced into the soil in various chemical forms.

  10. Synthesis and characterization of palladium nanoparticles using Catharanthus roseus leaf extract and its application in the photo-catalytic degradation

    Science.gov (United States)

    Kalaiselvi, Aasaithambi; Roopan, Selvaraj Mohana; Madhumitha, Gunabalan; Ramalingam, C.; Elango, Ganesh

    2015-01-01

    The potential effect of Catharanthus roseus leaf extract for the formation of palladium nanoparticles and its application on dye degradation was discussed. The efficiency of C.roseus leaves are used as a bio-material for the first time as reducing agent. Synthesized palladium nanoparticles were supported by UV-vis spectrometry, XRD, FT-IR and TEM analysis. The secondary metabolites which are responsible for the formation of nanoparticles were identified by GC-MS. The results showed that effect of time was directly related to synthesized nanoparticles and functional groups has a critical role in reducing the metal ions and stabilizing the palladium nanoparticles in an eco-friendly process.

  11. A Palladium-Catalyzed Vinylcyclopropane (3 + 2) Cycloaddition Approach to the Melodinus Alkaloids

    KAUST Repository

    Goldberg, Alexander F. G.

    2011-08-19

    A palladium-catalyzed (3+2) cycloaddition of a vinylcyclopropane and a β-nitrostyrene is employed to rapidly assemble the cyclopentane core of the Melodinus alkaloids. The ABCD ring system of the natural product family is prepared in six steps from commercially available materials.

  12. Shape-dependent electrocatalytic activity of monodispersed palladium nanocrystals toward formic acid oxidation

    Science.gov (United States)

    Zhang, Xuwei; Yin, Huajie; Wang, Jinfeng; Chang, Lin; Gao, Yan; Liu, Wei; Tang, Zhiyong

    2013-08-01

    The catalytic activity of different-shaped and monodispersed palladium nanocrystals, including cubes, octahedra and rhombic dodecahedra, toward the electrochemical oxidation of formic acid has been systematically evaluated in both HClO4 and H2SO4 solutions. Notably, the cubic palladium nanocrystals wholly exposed with {100} facets exhibit the highest activity, while the rhombic dodecahedra with {110} facets show the lowest electrocatalytic performance. Furthermore, compared with HClO4 electrolyte, the catalytic activity is found to be obviously lower in H2SO4 solution likely due to the competitive adsorption of SO42- ions and formic acid on the surface of Pd nanocrystals.The catalytic activity of different-shaped and monodispersed palladium nanocrystals, including cubes, octahedra and rhombic dodecahedra, toward the electrochemical oxidation of formic acid has been systematically evaluated in both HClO4 and H2SO4 solutions. Notably, the cubic palladium nanocrystals wholly exposed with {100} facets exhibit the highest activity, while the rhombic dodecahedra with {110} facets show the lowest electrocatalytic performance. Furthermore, compared with HClO4 electrolyte, the catalytic activity is found to be obviously lower in H2SO4 solution likely due to the competitive adsorption of SO42- ions and formic acid on the surface of Pd nanocrystals. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03100d

  13. Green synthesis of palladium nanoparticles with carboxymethyl cellulose for degradation of azo-dyes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gang; Li, Yun; Wang, Zhengdong; Liu, Huihong, E-mail: huihongliu@126.com

    2017-02-01

    Palladium nanoparticles (PdNPs) were synthesized through friendly environmental method using PdCl{sub 2} and carboxymethyl cellulose (CMC) in an aqueous solution (pH 6) at controlled water bath (80 °C) for 30 min. CMC functioned as both reducing and stabilizing agent. The characterization through high resolution-transmission electron microscopic (HRTEM) and X-ray Fluorescence Spectrometry (XRF) inferred that the as-synthesized PdNPs were spherical in shape with a face cubic crystal (FCC) structure. The results from dynamic light scattering (DLS) suggested the PdNPs had the narrow size distribution with an average size of 2.5 nm. The negative zeta potential (−52.6 mV) kept the as-synthesized PdNPs stable more than one year. The PdNPs showed the excellent catalytic activity by reducing degradation of azo-dyes, such as p-Aminoazobenzene, acid red 66, acid orange 7, scarlet 3G and reactive yellow 179, in the present of sodium borohydride. - Highlights: • Green synthesis of palladium nanoparticles using carboxymethyl cellulose. • The synthesis of palladium nanoparticles were performed easily. • Carboxymethyl cellulose acts as both reducing and stabilization agents. • The as-synthesized palladium nanoparticles show excellent catalytic activity.

  14. Magnetic silica supported palladium catalyst: synthesis of allyl aryl ethers in water

    Science.gov (United States)

    A simple and benign procedure for the synthesis of aryl allyl ethers has been developed using phenols, allyl acetates and magnetically recyclable silica supported palladium catalyst in water; performance of reaction in air and easy separation of the catalyst using an external mag...

  15. GREEN SYNTHESIS OF SILVER AND PALLADIUM NANOPARTICLES AT ROOM TEMPERATURE USING COFFEE AND TEA EXTRACT

    Science.gov (United States)

    An extremely simple green approach that generates bulk quantities of nanocrystals of noble metals such as silver (Ag) and palladium (Pd) using coffee and tea extract at room temperature is described. The single-pot method uses no surfactant, capping agent, and/or template. The ob...

  16. Preparation of fluorinated biaryls through direct palladium-catalyzed coupling of polyfluoroarenes with aryltrifluoroborates

    KAUST Repository

    Fang, Xin

    2013-07-01

    The direct palladium-catalyzed coupling of polyfluoroarenes with aryltrifluoroborates gave the desired products of fluorinated biaryls in good to excellent yields. A diverse set of important functional groups including methoxy, aldehyde, ester, nitro and halide can be well tolerated in the protocol. © 2013 Elsevier B.V. All rights reserved.

  17. Bulky Monodentate Phosphoramidites in Palladium-Catalyzed Allylic Alkylation Reactions : Aspects of Regioselectivity and Enantioselectivity

    NARCIS (Netherlands)

    Boele, Maarten D.K.; Kamer, Paul C.J.; Lutz, Martin; Spek, Anthony L.; Vries, Johannes G. de; Leeuwen, Piet W.N.M. van; Strijdonck, Gino P.F. van

    2004-01-01

    A series of bulky monodentate phosphoramidite ligands, based on biphenol, BINOL and TADDOL backbones, have been employed in the Pd-catalysed allylic alkylation reaction. Reaction of disodium diethyl 2-methyl malonate with monosubstituted allylic substrates in the presence of palladium complexes of

  18. Palladium(II)/Brønsted Acid-Catalyzed Enantioselective Oxidative Carbocyclization–Borylation of Enallenes**

    Science.gov (United States)

    Jiang, Tuo; Bartholomeyzik, Teresa; Mazuela, Javier; Willersinn, Jochen; Bäckvall, Jan-E

    2015-01-01

    An enantioselective oxidative carbocyclization–borylation of enallenes that is catalyzed by palladium(II) and a Brønsted acid was developed. Biphenol-type chiral phosphoric acids were superior co-catalysts for inducing the enantioselective cyclization. A number of chiral borylated carbocycles were synthesized in high enantiomeric excess. PMID:25808996

  19. The complex thiol-palladium interface: a theoretical and experimental study.

    Science.gov (United States)

    Carro, Pilar; Corthey, Gastón; Rubert, Aldo A; Benitez, Guillermo A; Fonticelli, Mariano H; Salvarezza, Roberto C

    2010-09-21

    This paper presents a theoretical study of the surface structures and thermodynamic stability of different thiol and sulfide structures present on the palladium surface as a function of the chemical potential of the thiol species. It has been found that as the chemical potential of the thiol is increased, the initially clean palladium surface is covered by a (√3 × √3)R30° sulfur lattice. Further increase in the thiol pressure or concentration leads to the formation of a denser (√7 × √7)R19.1° sulfur lattice, which finally undergoes a phase transition to form a complex (√7 × √7)R19.1° sulfur + thiol adlayer (3/7 sulfur + 2/7 thiol coverage). This transition is accompanied by a strong reconstruction of the Pd(111) surface. The formation of these surface structures has been explained in terms of the catalytic properties of the palladium surface. These results have been compared with X-ray photoelectron spectroscopy results obtained for thiols adsorbed on different palladium surfaces.

  20. Palladium-catalysed arylation of acetoacetate esters to yield 2-arylacetic acid esters

    CSIR Research Space (South Africa)

    Zeevaart, JG

    2004-05-24

    Full Text Available The coupling reaction between ethyl acetoacetate and a number of aryl halides in the presence of palladium acetate, a bulky and electron rich phosphine and K3PO4 is described. The arylated acetoacetate ester is de-acylated under the reaction...

  1. Practical and General Palladium-Catalyzed Synthesis of Ketones from Internal Olefins

    KAUST Repository

    Morandi, Bill

    2013-01-16

    Make it simple! A convenient and general palladium-catalyzed oxidation of internal olefins to ketones is reported. The transformation occurs at room temperature and shows wide substrate scope. Applications to the oxidation of seed-oil derivatives and a bioactive natural product (see scheme) are described, as well as intriguing mechanistic features.

  2. Preparation of potentially porous, chiral organometallic materials through spontaneous resolution of pincer palladium conformers.

    Science.gov (United States)

    Johnson, Magnus T; Džolić, Zoran; Cetina, Mario; Lahtinen, Manu; Ahlquist, Mårten S G; Rissanen, Kari; Öhrström, Lars; Wendt, Ola F

    2013-06-21

    Understanding the mechanism by which advanced materials assemble is essential for the design of new materials with desired properties. Here, we report a method to form chiral, potentially porous materials through spontaneous resolution of conformers of a PCP pincer palladium complex ({2,6-bis[(di-t-butylphosphino)methyl]phenyl}palladium(II)halide). The crystallisation is controlled by weak hydrogen bonding giving rise to chiral qtz-nets and channel structures, as shown by 16 such crystal structures for X = Cl and Br with various solvents like pentane and bromobutane. The fourth ligand (in addition to the pincer ligand) on palladium plays a crucial role; the chloride and the bromide primarily form hexagonal crystals with large 1D channels, whereas the iodide (presumably due to its inferior hydrogen bonding capacity) forms monoclinic crystals without channels. The hexagonal channels are completely hydrophobic and filled with disordered solvent molecules. Upon heating, loss of the solvent occurs and the hexagonal crystals transform into other non-porous polymorphs. Also by introducing a strong acid, the crystallisation process can be directed to a different course, giving several different non-porous polymorphs. In conclusion, a number of rules can be formulated dictating the formation of hexagonal channel structures based on pincer palladium complexes. Such rules are important for a rational design of future self-assembling materials with applications in storage and molecular recognition.

  3. Dendrimer-Encapsulated Palladium Nanoparticles for Continuous-Flow Suzuki–Miyaura Cross-Coupling Reactions

    NARCIS (Netherlands)

    Ricciardi, R.; Huskens, Jurriaan; Holtkamp, M.; Karst, U.; Verboom, Willem

    2015-01-01

    Generation three, four, and five (G3, G4, and G5) poly(amidoamine) dendrimers were used for the encapsulation of palladium nanoparticles (Pd NPs) and their covalent anchoring within glass microreactors. G3-encapsulated Pd NPs showed the highest activity for a model Suzuki–Miyaura cross-coupling

  4. Halide-Enhanced Catalytic Activity of Palladium Nanoparticles Comes at the Expense of Catalyst Recovery

    Directory of Open Access Journals (Sweden)

    Azzedine Bouleghlimat

    2017-09-01

    Full Text Available In this communication, we present studies of the oxidative homocoupling of arylboronic acids catalyzed by immobilised palladium nanoparticles in aqueous solution. This reaction is of significant interest because it shares a key transmetallation step with the well-known Suzuki-Miyaura cross-coupling reaction. Additives can have significant effects on catalysis, both in terms of reaction mechanism and recovery of catalytic species, and our aim was to study the effect of added halides on catalytic efficiency and catalyst recovery. Using kinetic studies, we have shown that added halides (added as NaCl and NaBr can increase the catalytic activity of the palladium nanoparticles more than 10-fold, allowing reactions to be completed in less than half a day at 30 °C. However, this increased activity comes at the expense of catalyst recovery. The results are in agreement with a reaction mechanism in which, under conditions involving high concentrations of chloride or bromide, palladium leaching plays an important role. Considering the evidence for analogous reactions occurring on the surface of palladium nanoparticles under different reaction conditions, we conclude that additives can exert a significant effect on the mechanism of reactions catalyzed by nanoparticles, including switching from a surface reaction to a solution reaction. The possibility of this switch in mechanism may also be the cause for the disagreement on this topic in the literature.

  5. Mechanistic study of the hydrothermal reduction of palladium on the Tobacco mosaic virus.

    Science.gov (United States)

    Adigun, Oluwamayowa O; Freer, Alexander S; Miller, Jeffrey T; Loesch-Fries, L Sue; Kim, Bong Suk; Harris, Michael T

    2015-07-15

    The fundamental mechanisms governing reduction and growth of palladium on the genetically engineered Tobacco mosaic virus in the absence of an external reducer have been elucidated via in situ X-ray absorption spectroscopy. In recent years, many virus-inorganic materials have been synthesized as a means to produce high quality nanomaterials. However, the underlying mechanisms involved in virus coating have not been sufficiently studied to allow for directed synthesis. We combined XAS, via XANES and EXAFS analysis, with TEM to confirm an autocatalytic reduction mechanism mediated by the TMV1Cys surface. This reduction interestingly proceeds via two first order regimes which result in two linear growth regimes as spherical palladium nanoparticles are formed. By combining this result with particle growth data, it was discovered that the first regime describes growth of palladium nanoparticles on the virion while the second regime describes a second layer of larger particles which grew sporadically on the first palladium nanoparticle layer. Subsequent aggregation of free solution based spherical particles and metallized nanorods characterize a third and final regime. At the end of the second reduction regime, the average particle diameter of particles tethered to the TMV1Cys surface are approximately 4.5 nm. The use of XAS to simultaneously monitor the kinetics of biotemplated reactions along with growth of metal nanoparticles will provide insight into the pertinent reduction and growth mechanisms so that nanorod properties can be controlled through their populating nanoparticles. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Oxidative addition of aryl chlorides to monoligated palladium(0): A DFT-SCRF study

    DEFF Research Database (Denmark)

    Ahlquist, Mårten Sten Gösta; Norrby, Per-Ola

    2007-01-01

    Oxidative addition of aryl chlorides to palladium has been investigated by hybrid density functional theory methods (B3LYP), including a continuum model describing the solvent implicitly. A series of para-substituted aryl chlorides were studied to see the influence of electronic effects on the re...

  7. A Practical Recycle of a Ligand-Free Palladium Catalyst for Heck Reactions

    NARCIS (Netherlands)

    Vries, André H.M. de; Parlevliet, Floris J.; Schmieder-van de Vondervoort, Lizette; Mommers, John H.M.; Henderickx, Huub J.W.; Walet, Monique A.M.; Vries, Johannes G. de

    2002-01-01

    Ligand-free palladium can be recovered almost quantitatively from Heck reaction mixtures by filtration after its deposition on a carrier such as silica or celite. Subsequently, it is re-activated to its original activity by adding a small amount of iodine or bromine prior to the next reaction cycle.

  8. An investigation of a palladium catalysed biaryl synthesis of pyrrolophenanthridine derivatives. Extension of the Heck reaction

    Directory of Open Access Journals (Sweden)

    Garden Simon J.

    2000-01-01

    Full Text Available N-Benzylisatin derivatives have been found to readily undergo cyclisation via hydrogen halide elimination in a biaryl synthesis reaction when using palladium catalysts, in the absence of phosphine ligands, to yield oxopyrrolo[3,2,1-de]phenanthridine derivatives.

  9. Palladium(0)/NHC-Catalyzed Reductive Heck Reaction of Enones : A Detailed Mechanistic Study

    NARCIS (Netherlands)

    Raoufmoghaddam, Saeed; Mannathan, Subramaniyan; Minnaard, Adriaan J; de Vries, Johannes G; Reek, Joost N H

    2015-01-01

    We have studied the mechanism of the palladium-catalyzed reductive Heck reaction of para-substituted enones with 4-iodoanisole by using N,N-diisopropylethylamine (DIPEA) as the reductant. Kinetic studies and in situ spectroscopic analysis have provided a detailed insight into the reaction. Progress

  10. Palladium(0)​/NHC-​catalyzed reductive Heck reaction of enones: a detailed mechanistic study

    NARCIS (Netherlands)

    Raoufmoghaddam, S.; Mannathan, S.; Minnaard, A.J.; de Vries, J.G.; Reek, J.N.H.

    2015-01-01

    We have studied the mechanism of the palladium-​catalyzed reductive Heck reaction of para-​substituted enones with 4-​iodoanisole by using N,​N-​diisopropylethylamine (DIPEA) as the reductant. Kinetic studies and in situ spectroscopic anal. have provided a detailed insight into the reaction.

  11. Palladium-Catalyzed Polyfluorophenylation of Porphyrins with Bis(polyfluorophenylzinc Reagents

    Directory of Open Access Journals (Sweden)

    Toshikatsu Takanami

    2013-10-01

    Full Text Available A facile and efficient method for the synthesis of pentafluorophenyl- and related polyfluorophenyl-substituted porphyrins has been achieved via palladium-catalyzed cross-coupling reactions of brominated porphyrins with bis(polyfluorophenylzinc reagents. The reaction is applicable to a variety of free-base bromoporphyrins, their metal complexes, and a number of bis(polyfluorophenylzinc reagents.

  12. Palladium-Catalyzed Enantioselective Three-Component Synthesis of α-Substituted Amines.

    Science.gov (United States)

    Beisel, Tamara; Manolikakes, Georg

    2015-06-19

    The first general palladium-catalyzed, enantioselective three-component synthesis of α-arylamines starting from sulfonamides, aldehydes, and arylboronic acids has been developed. These reactions generate a wide array of α-arylamines with high yields and enantioselectivities. Notably, this process is tolerant to air and moisture, providing an operationally simple approach for the synthesis of chiral α-arylamines.

  13. Palladium-catalyzed carbonylative sonogashira coupling of aryl bromides using near stoichiometric carbon monoxide

    DEFF Research Database (Denmark)

    Neumann, Karoline T.; Laursen, Simon R.; Lindhardt, Anders T.

    2014-01-01

    A general procedure for the palladium-catalyzed carbonylative Sonogashira coupling of aryl bromides is reported, using near stoichiometric amounts of carbon monoxide. The method allows a broad substrate scope in moderate to excellent yields. The formed alkynone motive serves as a platform...

  14. Palladium-catalyzed oxidative carbonylation of alkyl and aryl indium reagents with CO under mild conditions.

    Science.gov (United States)

    Zhao, Yingsheng; Jin, Liqun; Li, Peng; Lei, Aiwen

    2008-07-23

    CO now can react with organoindium reagents. A novel palladium-catalyzed oxidative carbonylation reaction of organoindium reagents by CO gas with desyl chloride as oxidant was developed in supplementation with the classical methods for preparation of carboxylic acid derivatives. Primary, secondary alkyl indium reagents with beta-hydrogens and aryl indium reagents were suitable substrates, and the reaction could be carried out at 60 degrees C under 50 psi CO. Carbonylation of alkyl indium reagents can occur smoothly without additional base. Although the indium reagents were prepared from corresponding Grignard reagents (at low temperature), they displayed full compatibility with various functional groups under the protic reaction conditions. Preliminary mechanistic studies including stoichiometric and catalytic reaction examination provided evidence to support the operation of the mechanism consisted of oxidative addition of deslyl chloride to Pd(0) and quick tautomerization to give a palladium enolate species II (ROPdCl), displacement of the enolate group in II by R(2)OH, followed by CO insertion to give alkoxycarbonyl palladium complex V, which undergoes transmetalation with R(1)(3)In and reductive elimination to afford the product and a Pd(0) species. In this mechanism, the alkoxycarbonyl group was transferred to the palladium center prior to the alkyl group, different from traditional ways initiated from oxidative addition of alkyl halides to a Pd(0) species.

  15. Assembly of a Cost-Effective Anode Using Palladium Nanoparticles for Alkaline Fuel Cell Applications

    Science.gov (United States)

    Feliciano-Ramos, Ileana; Casan~as-Montes, Barbara; García-Maldonado, María M.; Menendez, Christian L.; Mayol, Ana R.; Díaz-Vazquez, Liz M.; Cabrera, Carlos R.

    2015-01-01

    Nanotechnology allows the synthesis of nanoscale catalysts, which offer an efficient alternative for fuel cell applications. In this laboratory experiment, the student selects a cost-effective anode for fuel cells by comparing three different working electrodes. These are commercially available palladium (Pd) and glassy carbon (GC) electrodes, and…

  16. Preparation of palladium nanoparticles on alumina surface by chemical co-precipitation method and catalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Avvaru Praveen; Kumar, B. Prem; Kumar, A.B.V. Kiran; Huy, Bui The [Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of); Lee, Yong-Ill, E-mail: yilee@changwon.ac.kr [Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Facile synthesis of palladium nanoparticles on alumina surface. Black-Right-Pointing-Pointer The surface morphology and properties of the nanocrystalline powders were characterized. Black-Right-Pointing-Pointer The catalytic activities of palladium nanoparticles were investigated. - Abstract: The present work reports a chemical co-precipitation process to synthesize palladium (Pd) nanoparticles using alumina as a supporting material. The optimized temperature for the formation of nanocrystalline palladium was found to be 600 Degree-Sign C. The X-ray diffraction (XRD) and Raman spectroscopy were used to study the chemical nature of the Pd in alumina matrix. The surface morphology and properties of the nanocrystalline powders were examined using thermogravimetric analysis (TG-DTA), XRD, Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The calcinations in different atmospheres including in the inert medium forms the pure nano Pd{sup 0} while in the atmospheric air indicates the existence pure Pd{sup 0} along with PdO nanoparticles. The catalytic activities of the as-synthesized nanocrystalline Pd nanoparticles in the alumina matrix were investigated in Suzuki coupling, Hiyama cross-coupling, alkene and alkyne hydrogenation, and aerobic oxidation reactions.

  17. Biscarbene palladium(II) complexes. Reactivity of saturated versus unsaturated N-heterocyclic carbenes

    NARCIS (Netherlands)

    Fu, C.F.; Lee, C.C.; Liu, Y.H.; Peng, S.M.; Warsink, S.; Elsevier, C.J.; Chen, J.T.; Liu, S.T.

    2010-01-01

    A series of designed palladium biscarbene complexes including saturated and unsaturated N-heterocyclic carbene (NHC) moieties have been prepared by the carbene transfer methods. All of these complexes have been characterized by 1H and 13C NMR spectroscopy as well as X-ray diffraction analysis. The

  18. Novel Base Metal-Palladium Catalytic Diesel Filter Coating with NO2 Reducing Properties

    DEFF Research Database (Denmark)

    Johansen, K.; Dahl, S.; Mogensen, G.

    2007-01-01

    price structure. The novel base metal/palladium catalytic coat has been applied on commercial silicon carbide wall flow diesel filters and tested in an engine test bench. Results from engine bench tests concerning soot combustion, HC-, CO-, NO2- removal with the novel coat will are compared to present...

  19. Memory effects in palladium-catalyzed allylic Alkylations of 2-cyclohexen-1-yl acetate

    DEFF Research Database (Denmark)

    Svensen, Nina; Fristrup, Peter; Tanner, David Ackland

    2007-01-01

    The objective of this work was to characterize the enantiospecificity of the allylic alkylation of enantioenriched 2-cyclohexen-1-yl acetate with the enolate ion of dimethyl malonate catalyzed by unsymmetrical palladium catalysts. The precatalysts employed were (eta(3)-allyl)PdLCl, where L...

  20. Palladium-catalysed direct cross-coupling of secondary alkyllithium reagents

    NARCIS (Netherlands)

    Vila, Carlos; Giannerini, Massimo; Hornillos, Valentin; Fananas-Mastral, Martin; Feringa, Ben L.

    2014-01-01

    Palladium-catalysed cross-coupling of secondary C(sp(3)) organometallic reagents has been a long-standing challenge in organic synthesis, due to the problems associated with undesired isomerisation or the formation of reduction products. Based on our recently developed catalytic C-C bond formation

  1. The metallation of N,N-dimethylaminotoluene by palladium acetate. Evidence for a trinuclear species

    NARCIS (Netherlands)

    Koten, G. van; Pfeffer, M.; Wehman, E.

    1985-01-01

    The reaction of cis or trans di(@m-chloro)bis{[2-(dimethylamino)phenyl]methyl}dipalladium with silver acetate affords the corresponding trans dimeric compound with two acetato bridges between the palladium atoms. The molecule is non-rigid in solution. A closer investigation of the product obtained

  2. Bulk and Surface Structures of Palladium-Modified Copper-Zinc Oxides ex Hydroxycarbonate Precursors

    NARCIS (Netherlands)

    López Granados, M.; Melián-Cabrera, I.; Fierro, J.L.G.

    2002-01-01

    (Pd)-Cu-Zn ex hydroxycarbonate precursors were prepared and characterized by several bulk and surface techniques. A palladium-free Cu-Zn precursor (CZ) was prepared by coprecipitation. Two Pd-Cu-Zn samples were prepared by coprecipitation (PCZ-CP) and sequential precipitation (PCZ-SP). It is shown

  3. Palladium-Catalyzed Regioselective C8-H Amination of 1-Naphthylamine Derivatives with Aliphatic Amines.

    Science.gov (United States)

    Li, Zexian; Sun, Suyan; Qiao, Huijie; Yang, Fan; Zhu, Yu; Kang, Jianxun; Wu, Yusheng; Wu, Yangjie

    2016-09-16

    A simple and facile protocol for palladium-catalyzed picolinamide-directed C8-H amination of 1-naphthylamine derivatives with simple secondary aliphatic amines was developed, thereby providing a new route to 1,8-naphthalenediamine derivatives. It is noteworthy that the picolinamide moiety as a bidentate directing group may play a key role in this regioselective transformation.

  4. Silver-palladium catalysts for the direct synthesis of hydrogen peroxide

    Science.gov (United States)

    Khan, Zainab; Dummer, Nicholas F.; Edwards, Jennifer K.

    2017-11-01

    A series of bimetallic silver-palladium catalysts supported on titania were prepared by wet impregnation and assessed for the direct synthesis of hydrogen peroxide, and its subsequent side reactions. The addition of silver to a palladium catalyst was found to significantly decrease hydrogen peroxide productivity and hydrogenation, but crucially increase the rate of decomposition. The decomposition product, which is predominantly hydroxyl radicals, can be used to decrease bacterial colonies. The interaction between silver and palladium was characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The results of the TPR and XPS indicated the formation of a silver-palladium alloy. The optimal 1% Ag-4% Pd/TiO2 bimetallic catalyst was able to produce approximately 200 ppm of H2O2 in 30 min. The findings demonstrate that AgPd/TiO2 catalysts are active for the synthesis of hydrogen peroxide and its subsequent decomposition to reactive oxygen species. The catalysts are promising for use in wastewater treatment as they combine the disinfectant properties of silver, hydrogen peroxide production and subsequent decomposition. This article is part of a discussion meeting issue 'Providing sustainable catalytic solutions for a rapidly changing world'.

  5. A DFT study on the mechanism of palladium-catalyzed divergent ...

    Indian Academy of Sciences (India)

    gent reactions reported by Liang group. Here, we present a detailed DFT study on the mechanism of palladium-catalyzed reaction of enyne carbonates to give the corresponding vinylidenepyridines or vinyli- denepyrrolidines based on the experiment reported by. Liang et al. In the experimental studies, Pd(dba)2 was. 547 ...

  6. PALLADIUM-FACILITATED ELECTROLYTIC DECHLORINATION OF 2-CHLOROBIPHENYL USING A GRANULAR-GRAPHITE ELECTRODE.

    Science.gov (United States)

    Palladium-assisted electrocatalytic dechlorination of 2-chlorobiphenyl (2-Cl BP) in aqueous solutions was conducted in a membrane-separated electrochemical reactor with granular-graphite packed electrodes. The dechlorination took place at a granular-graphite cathode while Pd was ...

  7. Determination of palladium by on-line flow-injection direct spectrophotometry in environmental samples using 2,2'-furyldioxime as a chelator.

    Science.gov (United States)

    Saçmacı, Serife; Kartal, Senol

    2013-05-15

    A new, sensitive, and accurate on-line spectrophotometric method for the determination of palladium was developed. The method is based on the reaction between Pd(II) and 2,2'-furyldioxime in nitric acid medium. The absorbance of the complex is spectrophotometrically measured at 410 nm with a diode-array detector. Several factors that influence the analytical performance of the method such as acidity, flow rates of the reagent and sample solutions, concentration of the reagent, and effect of interfering ions were investigated. The calibration curve was obtained in the range of 0.01-10.0 mg L(-1) Pd(II). The detection limit was 0.1 µg L(-1) while the relative standard deviation of the method was found to be 1.2% (n=13) at 4.0 mg L(-1) Pd(II) level. The sample throughput was 275 h(-1). The method was successfully applied to the determination of palladium in catalytic converter, anodic slime, road sediment, ore, and water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Low temperature and cost-effective growth of vertically aligned carbon nanofibers using spin-coated polymer-stabilized palladium nanocatalysts

    Science.gov (United States)

    Saleem, Amin M.; Shafiee, Sareh; Krasia-Christoforou, Theodora; Savva, Ioanna; Göransson, Gert; Desmaris, Vincent; Enoksson, Peter

    2015-02-01

    We describe a fast and cost-effective process for the growth of carbon nanofibers (CNFs) at a temperature compatible with complementary metal oxide semiconductor technology, using highly stable polymer-Pd nanohybrid colloidal solutions of palladium catalyst nanoparticles (NPs). Two polymer-Pd nanohybrids, namely poly(lauryl methacrylate)-block-poly((2-acetoacetoxy)ethyl methacrylate)/Pd (LauMAx-b-AEMAy/Pd) and polyvinylpyrrolidone/Pd were prepared in organic solvents and spin-coated onto silicon substrates. Subsequently, vertically aligned CNFs were grown on these NPs by plasma enhanced chemical vapor deposition at different temperatures. The electrical properties of the grown CNFs were evaluated using an electrochemical method, commonly used for the characterization of supercapacitors. The results show that the polymer-Pd nanohybrid solutions offer the optimum size range of palladium catalyst NPs enabling the growth of CNFs at temperatures as low as 350 °C. Furthermore, the CNFs grown at such a low temperature are vertically aligned similar to the CNFs grown at 550 °C. Finally the capacitive behavior of these CNFs was similar to that of the CNFs grown at high temperature assuring the same electrical properties thus enabling their usage in different applications such as on-chip capacitors, interconnects, thermal heat sink and energy storage solutions.

  9. Palladium Surface Modification of Nanocrystalline Sol-Gel Derived Zinc Oxide Thin Films and its Effect on Methane Sensing

    Directory of Open Access Journals (Sweden)

    P. BHATTACHARYYA

    2009-11-01

    Full Text Available Nanocrystalline n-ZnO thin films were deposited on SiO2-coated p-Si substrates by a sol-gel method to fabricate ZnO-based resistive sensors. Two types of sol-gel ZnO based sensor structure, one as deposited and other with surface modified by palladium were investigated for methane sensing. The response magnitude, response time and recovery time were studied in the temperature range of 100-350 °C and at methane concentrations of 0.01 %, 0.05 %, 0.1 %, 0.5 %, 1 % and 1.5 % for both the sensor structure. The Pd modified sol-gel ZnO based sensor was found to provide lower operating temperature (150 °C, lower response (recovery time, higher response magnitude and higher sensing range for methane compared to its earlier reported unmodified counterpart (250 °C. With Pd modification ZnO was found to sense methane concentration as low as 0.01 % and as high as 1.5 % whereas for unmodified one this range was restricted between 0.1 % to 1.0 %.

  10. Incorporating Feminist Standpoint Theory

    DEFF Research Database (Denmark)

    Ahlström, Kristoffer

    2005-01-01

    As has been noted by Alvin Goldman, there are some very interesting similarities between his Veritistic Social Epistemology (VSE) and Sandra Harding’s Feminist Standpoint Theory (FST). In the present paper, it is argued that these similarities are so significant as to motivate an incorporation...

  11. Anthrobiogeochemical platinum, palladium and rhodium cycles of earth: Emerging environmental contamination

    Science.gov (United States)

    Mitra, Arijeet; Sen, Indra Sekhar

    2017-11-01

    Anthrobiogeochemical cycles have been a subject of scientific research for many decades as they are important for identifying possible sources, sinks, and pathways of an element in the environment. In this study, we quantified global cycles for the platinum group elements (PGE; platinum (Pt), palladium (Pd) and rhodium (Rh)). We quantified the stocks of Pt, Pd, and Rh in Earth's various reservoirs, such as the core, mantle, consolidated crust, biomass, seawater, unconsolidated sediments, and atmosphere, as well as coal and petroleum deposits. We further quantified their fluxes, both natural and anthropogenic, between each reservoir, by identifying the flows across the hydrosphere, geosphere, biosphere, atmosphere and anthroposphere, including from mining activities, fossil fuel and biomass burning, construction activities, soil erosion, human contributions to net primary productivity, riverine transport, aeolian dust movement, primary production, volcanic eruption, sea-salt spray, crustal subduction, crust formation at mid ocean ridges, PGE recovery from recycling processes, and cosmic dust inputs at the Earth's surface. Stocks of PGEs were quantified by multiplying the mass of the reservoir by the average Pt, Pd and Rh concentration in the reservoir, whereas Pt, Pd and Rh fluxes were calculated by multiplying the rate of mass movement across the reservoirs with the Pt, Pd and Rh concentrations of the material. Uncertainties were explicitly incorporated in stock and flow estimations through Monte Carlo simulations. Our calculations reveal that the total surficial anthropogenic Pt, Pd, and Rh mobilizations were greater than their corresponding natural surficial mobilizations. We show that crustal subduction and crustal formation is the most important natural flow and contributes 21-42% of total PGE mobilization. When Earth's surficial processes are considered, soil erosion is the dominant flow for Rh and Pt mobilization, comprising 33% and 13%, respectively, of the

  12. Characterization of intracellular palladium nanoparticles synthesized by Desulfovibrio desulfuricans and Bacillus benzeovorans

    Energy Technology Data Exchange (ETDEWEB)

    Omajali, Jacob B., E-mail: JBO037@bham.ac.uk, E-mail: jbomajali@gmail.com; Mikheenko, Iryna P. [University of Birmingham, Unit of Functional Bionanomaterials, School of Biosciences, Institute of Microbiology and Infection (United Kingdom); Merroun, Mohamed L. [University of Granada, Department of Microbiology, Faculty of Sciences (Spain); Wood, Joseph [University of Birmingham, School of Chemical Engineering (United Kingdom); Macaskie, Lynne E. [University of Birmingham, Unit of Functional Bionanomaterials, School of Biosciences, Institute of Microbiology and Infection (United Kingdom)

    2015-06-15

    Early studies have focused on the synthesis of palladium nanoparticles within the periplasmic layer or on the outer membrane of Desulfovibrio desulfuricans and on the S-layer protein of Bacillus sphaericus. However, it has remained unclear whether the synthesis of palladium nanoparticles also takes place in the bacterial cell cytoplasm. This study reports the use of high-resolution scanning transmission electron microscopy with a high-angle annular dark field detector and energy dispersive X-ray spectrometry attachment to investigate the intracellular synthesis of palladium nanoparticles (Pd NPs). We show the intracellular synthesis of Pd NPs within cells of two anaerobic strains of D. desulfuricans and an aerobic strain of B. benzeovorans using hydrogen and formate as electron donors. The Pd nanoparticles were small and largely monodispersed, between 0.2 and 8 nm, occasionally from 9 to 12 nm with occasional larger nanoparticles. With D. desulfuricans NCIMB 8307 (but not D. desulfuricans NCIMB 8326) and with B. benzeovorans NCIMB 12555, the NPs were larger when made at the expense of formate, co-localizing with phosphate in the latter, and were crystalline, but were amorphous when made with H{sub 2,} with no phosphorus association. The intracellular Pd nanoparticles were mainly icosahedrons with surfaces comprising {111} facets and about 5 % distortion when compared with that of bulk palladium. The particles were more concentrated in the cell cytoplasm than the cell wall, outer membrane, or periplasm. We provide new evidence for synthesis of palladium nanoparticles within the cytoplasm of bacteria, which were confirmed to maintain cellular integrity during this synthesis.

  13. Characterization of intracellular palladium nanoparticles synthesized by Desulfovibrio desulfuricans and Bacillus benzeovorans

    Science.gov (United States)

    Omajali, Jacob B.; Mikheenko, Iryna P.; Merroun, Mohamed L.; Wood, Joseph; Macaskie, Lynne E.

    2015-06-01

    Early studies have focused on the synthesis of palladium nanoparticles within the periplasmic layer or on the outer membrane of Desulfovibrio desulfuricans and on the S-layer protein of Bacillus sphaericus. However, it has remained unclear whether the synthesis of palladium nanoparticles also takes place in the bacterial cell cytoplasm. This study reports the use of high-resolution scanning transmission electron microscopy with a high-angle annular dark field detector and energy dispersive X-ray spectrometry attachment to investigate the intracellular synthesis of palladium nanoparticles (Pd NPs). We show the intracellular synthesis of Pd NPs within cells of two anaerobic strains of D. desulfuricans and an aerobic strain of B. benzeovorans using hydrogen and formate as electron donors. The Pd nanoparticles were small and largely monodispersed, between 0.2 and 8 nm, occasionally from 9 to 12 nm with occasional larger nanoparticles. With D. desulfuricans NCIMB 8307 (but not D. desulfuricans NCIMB 8326) and with B. benzeovorans NCIMB 12555, the NPs were larger when made at the expense of formate, co-localizing with phosphate in the latter, and were crystalline, but were amorphous when made with H2, with no phosphorus association. The intracellular Pd nanoparticles were mainly icosahedrons with surfaces comprising {111} facets and about 5 % distortion when compared with that of bulk palladium. The particles were more concentrated in the cell cytoplasm than the cell wall, outer membrane, or periplasm. We provide new evidence for synthesis of palladium nanoparticles within the cytoplasm of bacteria, which were confirmed to maintain cellular integrity during this synthesis.

  14. Sugar and heavy atom effects of glycoconjugated chlorin palladium complex on photocytotoxicity.

    Science.gov (United States)

    Hirohara, Shiho; Kawasaki, Yuji; Funasako, Ryota; Yasui, Nobutaka; Totani, Masayasu; Alitomo, Hiroki; Yuasa, Junpei; Kawai, Tuyoshi; Oka, Chio; Kawaichi, Masashi; Obata, Makoto; Tanihara, Masao

    2012-09-19

    Palladium(II) complexes of glycoconjugated porphyrin and pyrrolidine-fused chlorin were prepared to examine sugar and heavy atom effects on in vitro photocytotoxicity. Cellular uptake into HeLa cells was enhanced by introducing sugar units regardless of other features, such as the central ion (free base or palladium(II) ion) and the ring structure (porphyrin or chlorin). The palladium(II) complex of glycoconjugated pyrrolidine-fused chlorin (PdPC2) exerted an excellent degree of photocytotoxicity not only on HeLa cells, but also on metastatic B16-BL6 cells, weakly metastatic B16F1 cells, and metastatic 4T1 cells. However, free-base glycoconjugated pyrrolidine-fused chlorin (PC2) also exerted similar or much higher photocytotoxicity rather than PdPC2. Therefore, the palladium(II) ion did not improve the in vitro photocytotoxicity of PC2. The enhanced singlet oxygen generation of palladium(II) complexes (i.e., the heavy atom effect) was confirmed at least in O(2)-saturated D(2)O. In addition, the formation of hydrogen peroxide and hydroxyl radical were also detected in O(2)-saturated phosphate buffered saline. However, the reactive oxygen species (ROS) generation efficiency, which is the product of the (relative) quantum yield of each ROS and the light absorbing ability, did not fit the trends of photocytotoxicity seen for the photosensitizers. In our glycoconjugated photosensitizers tested, the best indicator of the photocytotoxicity was found to be the light absorbing ability (namely, the oscillator strength in the wavelength region applied in the photocytotoxicity test). These results indicated that photochemical characteristics of glycoconjugated photosensitizers were notably susceptible to the microenvironment. The biological characteristics, such as the sugar effect, were a much more reliable approach to improving the photocytotoxicity of photosensitizers.

  15. Study of the elimination on palladium three-way catalysts of the different unburnt hydrocarbons types contained in automobiles exhaust gases; Etude de l`elimination sur catalyseurs trois-voies a base de palladium des differentes categories d`hydrocarbures imbrules presentes dans les gaz d`echappement automobiles

    Energy Technology Data Exchange (ETDEWEB)

    Amon-Meziere, I.

    1996-04-22

    This work was done about a study of behaviour of automotive three-way catalyst containing palladium. In particularly the conversion of many hydrocarbons and oxygenate compounds was studied either alone or mixed. The temperature range of reaction, the influence of the hydrocarbon nature on his conversion, the effect of thermal ageing of catalyst and the effect of dioxide sulfur on the hydrocarbon oxidation was clarified. We have showed the different reaction who were done at the time of different pollutant conversion (CO, NO and one HC) and the influence of different species present in a real exhaust gas on the catalytic oxidation of propane and propane has been checked. We have concluded that the presence of the other species in the gas mixture did not modify very much the activities of the catalyst toward hydrocarbon conversion under stoichiometric conditions, that the slow step of hydrocarbon oxidation is the absorption of molecule and that under oxidizing conditions propane conversion was effected by oxygen. Then we have evaluated our palladium/rhodium three-way catalyst as regards its effectiveness in the catalytic oxidation of different hydrocarbon species and oxygenated compounds taken individually. Two categories of hydrocarbons can also distinguished: first the short chain alkanes and then the long chain alkanes and the other hydrocarbons. We have showed the inhibiting effect of hydrocarbons as concerns CO oxidation and NO reduction. And the study of hydrocarbons mixtures has showed an inhibiting effect of one hydrocarbon on the oxidation of the hydrocarbons in few cases. The study of behaviour of the ageing catalyst containing palladium has showed an important decrease of its effectiveness who can be explained by the decrease of active site number. Some ppm of sulfur dioxide in gas mixture resulted in its inhibiting effect of all species conversion. (author) 74 refs.

  16. Observation of stable Néel skyrmions in cobalt/palladium multilayers with Lorentz transmission electron microscopy

    National Research Council Canada - National Science Library

    Shawn D Pollard; Joseph A Garlow; Jiawei Yu; Zhen Wang; Yimei Zhu; Hyunsoo Yang

    2017-01-01

    ... with a strong Dzyaloshinskii-Moriya interaction. Here we report on the direct imaging of chiral spin structures including skyrmions in an exchange-coupled cobalt/palladium multilayer at room temperature with Lorentz transmission electron microscopy...

  17. SAXS characterization of genetically engineered tobacco mosaic virus nanorods coated with palladium in the absence of external reducing agents.

    Science.gov (United States)

    Freer, Alexander S; Guarnaccio, Lucas; Wafford, Kristin; Smith, Johanna; Steilberg, Jayne; Culver, James N; Harris, Michael T

    2013-02-15

    Genetic modifications of the tobacco mosaic virus (TMV) coat proteins allow for an increase in the selective deposition and controlled growth of different metals onto the surface of the virus, making it an ideal biotemplate for metal nanowire formation. In the current process, TMV2Cys is coated sequentially with multiple uniform layers of palladium metal in aqueous solution under very mild conditions. Palladium nanowires of 300 nm in length and 30-40 nm in diameter have been created with this process. Transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) are used to characterize the thickness and uniformity of the metal surface. The TEM and SAXS results confirm that the final thickness of the palladium nanowires is controllable by varying the number of coating layers or the initial palladium concentration. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Influence of residual catalyst on the properties of conjugated polyphenylenevinylene materials: Palladium nanoparticles and poor electrical performance

    DEFF Research Database (Denmark)

    Krebs, Frederik C; Nyberg, R.B.; Jørgensen, M.

    2004-01-01

    (TEM). Further, electron spectroscopy for chemical analysis (ESCA), powder X-ray diffraction, and scanning electron microscopy (SEM) were employed to establish the chemical and physical nature of the catalyst remnants. We demonstrate the identity of many physical and chemical properties of the same......The synthesis of conjugated polymer materials using palladium catalysis was shown to result in a contamination of the polymer product with palladium nanoparticles that were difficult to detect and remove. The particle size was on the order of 20 nm, as evidenced by transmission electron microscopy...... polymer material prepared by two different routes: the palladium route and the condensation route. The performance in a device application of the two polymer materials was, however, very different, and the palladium route was demonstrated to give poor films with low breakdown voltages and short circuits....

  19. Some Properties of Platinum and Palladium Modified Aluminide Coatings Deposited by CVD Method on Nickel-Base Superalloys

    National Research Council Canada - National Science Library

    Zagula-Yavorska, M; Sieniawski, J; Gancarczyk, T

    2012-01-01

    In the paper some functional properties (hardness and oxidation resistance) of platinum and palladium modified aluminide coatings deposited by the CVD method on a nickel-based superalloy were determined...

  20. Stereoselective synthesis of tricyclic compounds by intramolecular palladium-catalyzed addition of aryl iodides to carbonyl groups

    Directory of Open Access Journals (Sweden)

    Jakub Saadi

    2016-06-01

    Full Text Available Starting from γ-ketoesters with an o-iodobenzyl group we studied a palladium-catalyzed cyclization process that stereoselectively led to bi- and tricyclic compounds in moderate to excellent yields. Four X-ray crystal structure analyses unequivocally defined the structure of crucial cyclization products. The relative configuration of the precursor compounds is essentially transferred to that of the products and the formed hydroxy group in the newly generated cyclohexane ring is consistently in trans-arrangement with respect to the methoxycarbonyl group. A transition-state model is proposed to explain the observed stereochemical outcome. This palladium-catalyzed Barbier-type reaction requires a reduction of palladium(II back to palladium(0 which is apparently achieved by the present triethylamine.

  1. Palladium(II) complexes bearing a salicylaldiminato ligand with a hydroxyl group: Synthesis, structures, deprotonation, and catalysis

    OpenAIRE

    Murata, Yusuke; Ohgi, Hiroyuki; Fujihara, Tetsuaki; Terao, Jun; Tsuji, Yasushi

    2011-01-01

    Palladium complexes with a salicylaldiminato ligand bearing a hydroxyl group (1a and 1b) have been synthesized and characterized. The structures of these complexes were confirmed by X-ray crystallography. A reversible deprotonation/protonation of the hydroxyl moiety on 1b was observed, while such behaviour was impossible with a related palladium complex (1c) bearing a methoxyl group in place of the hydroxyl group. The deprotonation affected its catalytic behaviour: the activity for polymeriza...

  2. Decarbonylative Phosphorylation of Amides by Palladium and Nickel Catalysis: The Hirao Cross-Coupling of Amide Derivatives.

    Science.gov (United States)

    Liu, Chengwei; Szostak, Michal

    2017-10-02

    Considering the ubiquity of organophosphorus compounds in organic synthesis, pharmaceutical discovery agrochemical crop protection and materials chemistry, new methods for their construction hold particular significance. A conventional method for the synthesis of C-P bonds involves cross-coupling of aryl halides and dialkyl phosphites (the Hirao reaction). We report a catalytic deamidative phosphorylation of a wide range of amides using a palladium or nickel catalyst giving aryl phosphonates in good to excellent yields. The present method tolerates a wide range of functional groups. The reaction constitutes the first example of a transition-metal-catalyzed generation of C-P bonds from amides. This redox-neutral protocol can be combined with site-selective conventional cross-coupling for the regioselective synthesis of potential pharmacophores. Mechanistic studies suggest an oxidative addition/transmetallation pathway. In light of the importance of amides and phosphonates as synthetic intermediates, we envision that this Pd and Ni-catalyzed C-P bond forming method will find broad application. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Preparation of Palladium(II) Ion-Imprinted Polymeric Nanospheres and Its Removal of Palladium(II) from Aqueous Solution

    Science.gov (United States)

    Tao, Hu-Chun; Gu, Yi-Han; Liu, Wei; Huang, Shuai-Bin; Cheng, Ling; Zhang, Li-Juan; Zhu, Li-Li; Wang, Yong

    2017-11-01

    Three kinds of functional monomers, 4-vinylpridine(4-VP), 2-(allylthio)nicotinic acid(ANA), and 2-Acetamidoacrylic acid(AAA), were used to synthetize palladium(II) ion-imprinted polymeric nanospheres (Pd(II) IIPs) via precipitation-polymerization method in order to study the effects of different functional monomers on the adsorption properties of ion-imprinted materials. The results of UV spectra in order to study the interaction between template ion PdCl4 2- and functional monomers showed that there were great differences in structure after the template reacted with three functional monomers, 4-VP and ANA caused a large structural change, while AAA basically did not change. Further results on the adsorption performance of Pd(II) IIPs on Pd(II) confirmed 4-VP was the most promising candidate for the synthesis of Pd(II) IIPs with an adsorption capacity of 5.042 mg/g as compared with ANA and AAA. The influence of operating parameters on Pd(II) IIP's performance on Pd(II) adsorption was investigated. There was an increase in the adsorption capacity of Pd(II) IIPs at higher pH, temperature, and initial concentration of Pd(II). The results of multi-metal competitive adsorption experiments showed that Pd(II) IIPs had selectivity for Pd(II). An adsorption equilibrium could be reached at 180 min. Kinetic analysis showed that the adsorption test data fitted best to the pseudo-second order kinetic model, and the theoretical equilibrium adsorption capacity was about 5.085 mg/g. The adsorption isotherms of Pd(II) by Pd(II) IIPs agreed well with the Freundlich equation, suggesting a favorable adsorption reaction under optimal conditions. These results showed that Pd(II) IIPs have potential application in the removal of Pd(II) from aqueous solutions and may provide some information for the selection of functional monomers in the preparation of Pd(II) IIPs.

  4. Determination of palladium in various samples by atomic absorption spectrometry after preconcentration with dimethylglyoxime on silica gel

    Energy Technology Data Exchange (ETDEWEB)

    Tokalioglu, Serife; Oymak, Tuelay; Kartal, Senol

    2004-05-31

    A preconcentration method based on the adsorption of palladium-dimethylglyoxime (DMG) complex on silica gel for the determination of palladium at trace levels by atomic absorption spectrometry (AAS) has been developed. The retained palladium as Pd(DMG){sub 2} complex was eluted with 1 mol l{sup -1} HCl in acetone. The effect of some analytical parameters such as pH, amount of reagent and the sample volume on the recovery of palladium was examined in synthetic solutions containing street dust matrix. The influence of some matrix ions on the recovery of palladium was investigated by using the developed method when the elements were present both individually and together. The results showed that 2500 {mu}g ml{sup -1} Na{sup +}, K{sup +}, Mg{sup 2+}, Al{sup 3+} and Fe{sup 3+}; 5000 {mu}g ml{sup -1} Ca{sup 2+} ; 500 {mu}g ml{sup -1} Pb{sup 2+}; 125 {mu}g ml{sup -1} Zn{sup 2+}; 50 {mu}g ml{sup -1} Cu{sup 2+} and 25 {mu}g ml{sup -1} Ni{sup 2+} did not interfere with the palladium signal. At the optimum conditions determined experimentally, the recovery for palladium was found to be 95.3{+-}1.2% at the 95% confidence level. The relative standard deviation and limit of detection (3s/b) of the method were found to be 1.7% and 1.2 {mu}g l{sup -1}, respectively. In order to determine the adsorption behaviour of silica gel, the adsorption isotherm of palladium was studied and the binding equilibrium constant and adsorption capacity were calculated to be 0.38 l mg{sup -1} and 4.06 mg g{sup -1}, respectively. The determination of palladium in various samples was performed by using both flame AAS and graphite furnace AAS. The proposed method was successfully applied for the determination of palladium in the street dust, anode slime, rock and catalytic converter samples.

  5. Synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel for electrochemical detection of dopamine

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ruiyi; Yang, Tingting [School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122 (China); Li, Zaijun, E-mail: zaijunli@jiangnan.edu.cn [School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122 (China); Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, Wuxi 214122 (China); Gu, Zhiguo; Wang, Guangli; Liu, Junkang [School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122 (China)

    2017-02-15

    Integration of noble metal nanomaterials on graphene nanosheets potentially paves one way to improve their electronic, chemical and electrochemical properties. The study reported synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel composite (Pd@Au/N,S-MGA). The as-prepared composite offers a well-defined three-dimensional architecture with rich of mesopores. The Pd@Au nanoalloys were dispersed on the graphene framework networks and their active sites were fully exposed. The unique structure achieves to ultra high electron/ion conductivity, electrocatalytic activity and structural stability. The sensor based on the Pd@Au/N,S-MGA creates ultrasensitive electrochemical response towards dopamine due to significantly electrochemical synergy between Pd, Au and N,S-MGA. Its differential pulse voltammetric signal linearly increases with the increase of dopamine concentration in the range from 1.0 × 10{sup −9} M to 4.0 × 10{sup −5} M with the detection limit of 3.6 × 10{sup −10} M (S/N = 3). The analytical method provides the advantage of sensitivity, reproducibility, rapidity and long-term stability. It has been successfully applied in the detection of trace dopamine in biological samples. The study also opens a window on the electronic properties of graphene aerogel and metal nanomaterials as well their nanohybrids to meet needs of further applications as nanoelectronics in diagnosis, bioanalysis and catalysis. - Graphical abstract: We reported a new palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel. The sensor based on the nanohybrid exhibits ultrahigh sensitivity, reproducibility and stability to electrochemical detection of dopamine. - Highlights: • We reported Pd@A/nitrogen and sulphur-functionalized multiple graphene aerogel. • The nanohybrid offers unique three-dimensional architecture with rich of mesopores. • The architecture achieve to ultrahigh

  6. Biscarbene palladium(II) complexes. reactivity of saturated versus unsaturated N-heterocyclic carbenes.

    Science.gov (United States)

    Fu, Ching-Feng; Lee, Chun-Chin; Liu, Yi-Hung; Peng, Shie-Ming; Warsink, Stefan; Elsevier, Cornelis J; Chen, Jwu-Ting; Liu, Shiuh-Tzung

    2010-03-15

    A series of designed palladium biscarbene complexes including saturated and unsaturated N-heterocyclic carbene (NHC) moieties have been prepared by the carbene transfer methods. All of these complexes have been characterized by (1)H and (13)C NMR spectroscopy as well as X-ray diffraction analysis. The reactivity of Pd-C((saturated NHC)) is distinct from that of Pd-C((unsaturated NHC)). The Pd-C((saturated NHC)) bonds are fairly stable toward reagents such as CF(3)COOH, AgBF(4) and I(2), whereas Pd-C((unsaturated NHC)) bonds are readily cleaved under the similar conditions. Notably, the catalytically activity of these palladium complexes on Suzuki-Miyaura coupling follows the order: (sat-NHC)(2)PdCl(2) > (sat-NHC)(unsat-NHC)PdCl(2 )> (unsat-NHC)(2)PdCl(2).

  7. PVP-Stabilized Palladium Nanoparticles in Silica as Effective Catalysts for Hydrogenation Reactions

    Directory of Open Access Journals (Sweden)

    Caroline Pires Ruas

    2013-01-01

    Full Text Available Palladium nanoparticles stabilized by poly (N-vinyl-2-pyrrolidone (PVP can be synthesized by corresponding Pd(acac2 (acac = acetylacetonate as precursor in methanol at 80°C for 2 h followed by reduction with NaBH4 and immobilized onto SiO2 prepared by sol-gel process under acidic conditions (HF or HCl. The PVP/Pd molar ratio is set to 6. The effect of the sol-gel catalyst on the silica morphology and texture and on Pd(0 content was investigated. The catalysts prepared (ca. 2% Pd(0/SiO2/HF and ca. 0,3% Pd(0/SiO2/HCl were characterized by TEM, FAAS, and SEM-EDS. Palladium nanoparticles supported in silica with a size 6.6 ± 1.4 nm were obtained. The catalytic activity was tested in hydrogenation of alkenes.

  8. Studies on nickel (II and palladium (II complexes with some tetraazamacrocycles containing tellurium

    Directory of Open Access Journals (Sweden)

    Rathee Nitu

    2012-01-01

    Full Text Available The synthesis of 10-membered and 12-membered tellurium containing tetraazamacrocyclic complexes of divalent nickel and palladium by template condensation of diaryltellurium dichlorides, (aryl = p-hydroxyphenyl, 3-methyl-4-hydroxyphenyl, p-methoxyphenyl with 1,2-diaminoethane and 1,3-diaminopropane in the presence of metal dichloride is reported. The resulting complexes have been subjected to elemental analyses, magnetic measurements, electronic absorption, infra-red, and proton magnetic resonance spectral studies. The formation of proposed macrocyclic skeletons and their donor sites have been identified on the basis of spectral studies. Distorted octahedral structure for the nickel complexes in the solid state and squareplanar structure for the palladium complexes have been suggested.

  9. Palladium polypyridyl complexes: synthesis, characterization, DNA interaction and biological activity on Leishmania (L.) mexicana

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, Maribel [Instituto Venezolano de Investigaciones Cientificas, Caracas (Venezuela). Centro de Quimica; Betancourt, Adelmo [Universidad de Carabobo, Valencia (Venezuela). Facultad Experimental de Ciencia y Tecnologia. Dept. de Quimica; Hernandez, Clara [Universidad de Carabobo Sede Aragua, Maracay (Venezuela). Facultad de Ciencias de la Salud. Dept. de Ciencias Basicas; Marchan, Edgar [Universidad de Oriente, Cumana (Venezuela). Inst. de Investigaciones en Biomedicina y Ciencias Aplicadas. Nucleo de Sucre

    2008-07-01

    This paper describes the search for new potential chemotherapeutic agents based on transition metal complexes with planar ligands. In this study, palladium polypyridyl complexes were synthesized and characterized by elemental analysis, NMR, UV-VIS and IR spectroscopies. The interaction of the complexes with DNA was also investigated by spectroscopic methods. All metal-to-ligand charge transfer (MLCT) bands of the palladium polypyridyl complexes exhibited hypochromism and red shift in the presence of DNA. The binding constant and viscosity data suggested that the complexes [PdCl{sub 2}(phen)] and [PdCl{sub 2}(phendiamine)] interact with DNA by electrostatic forces. Additionally, these complexes induced an important leishmanistatic effect on L. (L.) mexicana promastigotes at the final concentration of 10 {mu}mol L{sup -1} in 48 h. (author)

  10. Schiff base triphenylphosphine palladium (II) complexes: Synthesis, structural elucidation, electrochemical and biological evaluation

    Science.gov (United States)

    Shabbir, Muhammad; Akhter, Zareen; Ahmad, Iqbal; Ahmed, Safeer; Shafiq, Maryam; Mirza, Bushra; McKee, Vickie; Munawar, Khurram Shahzad; Ashraf, Ahmad Raza

    2016-08-01

    The complexes N-(2-oxidophenyl)salicylideneiminatotriphenylphosphine palladium(II) (1) and N-(2-sulfidophenyl)salicylideneiminato triphenylphosphine palladium(II) (2) of tridentate Schiff bases derived from salicylaldehyde and an amino- or thiophenol, have been synthesized and characterized by various spectroscopic, analytical and electro-analytical techniques. X-ray single crystal analysis of complex 1 has revealed its square planar geometry. The thermal analysis has shown the absence of coordinated water and final degradation product is PdO. The alkaline phosphatase studies have indicated that enzymatic activity is concentration dependent which is inversely proportional to the concentration of the compounds. The biological assays (brine shrimp cytotoxicity, DPPH) have reflected their biologically active and mild antioxidant nature. However, results of DNA protection assay have shown that they possess moderate protective activity against hydroxyl free radicals (rad OH). The voltammetric studies ascertain two-electron reduction of the compounds through purely diffusion controlled process and reveal intercalative mode of drug DNA interactions.

  11. Selective Heck Arylation of Cyclohexene with Homogeneous and Heterogeneous Palladium Catalysts

    Directory of Open Access Journals (Sweden)

    Ewa Mieczyńska

    2010-03-01

    Full Text Available Palladium catalysts containing Pd(II supported on Al2O3 and alumina-based mixed oxides, Al2O3-ZrO2, Al2O3-CeO2, and Al2O3-Fe2O3, are very effective in the Heck coupling of iodobenzene with cyclohexene in DMF solution. The best results, up to 81% of monoarylated products with a selectivity to 4-phenylcyclohexene (3 close to 90% were obtained with KOH as a base. The catalytic activity of palladium supported on alumina-based oxides was compared with that of homogeneous precursors, such as Pd(OAc2 and PdCl2(PhCN2, used in [Bu4N]Br as the reaction medium. Under such conditions homogeneous systems were more selective and produced up to 60% of monoarylated products with a selectivity to 3 close to 60%.

  12. Palladium-catalyzed asymmetric Heck arylation of 2,3-dihydrofuran--effect of prolinate salts.

    Science.gov (United States)

    Morel, Adam; Silarska, Ewelina; Trzeciak, Anna M; Pernak, Juliusz

    2013-01-28

    Chiral ionic liquids (CILs) containing L-prolinate and L-lactate anions and non-chiral quaternary ammonium cations were employed in the palladium catalyzed enantioselective Heck arylation of 2,3-dihydrofuran with aryl iodides (iodobenzene, 4-iodotoluene, 2-iodoanisole, 4-iodoanisole, 4-iodoacetophenone). In all the reactions 2-aryl-2,3-dihydrofuran (3) was obtained as the main product with the yield up to 52% at the total conversion reaching 83%. Product 3, 2-phenyl-2,3-dihydrofuran, was obtained with excellent enantioselectivity (>99% ee) in a 6 h reaction with tetrabutylammonium L-prolinate. In the proposed homogeneous reaction Pd(0) nanoparticles are considered as a resting state of the catalyst and a source of soluble palladium species catalyzing the Heck reaction. The yield and stereoselectivity of the Heck reaction are strongly influenced by the kind of non-chiral cations present in CILs.

  13. Evidence of alloy formation during the activation of graphite-supported palladium-cobalt catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Noronha, F.B.; Schmal, M. [Univ. Federal do Rio de Janeiro (Brazil); Frety, R. [CNRS, Villeurbanne (France). Lab. d`Application de la Chimie a l`Environnement; Bergeret, G.; Moraweck, B. [CNRS, Villeurbanne (France). Inst. de Recherches sur la Catalyse

    1999-08-15

    Magnetism, XRD, and EXAFS analyses were used to study the formation of a solid solution on Pd-Co/G catalysts during reduction treatment. After reduction at 773 K, magnetic measurements revealed the formation of a Pd-Co alloy. XRD analysis in situ allowed one to follow the alloy process during the increase of the reduction temperature. The XRD results showed the presence of a heterogeneous solid solution after reduction at 773 K. Pd and Co K-edge EXAFS analysis confirmed that bimetallic particles with a palladium- and cobalt-rich phase were formed. The formation of a solid solution decreased the adsorption strength of 1,3-butadiene on new Pd sites modified by Co. Palladium-cobalt catalysts are useful for methanol and ethanol formation from synthesis gas at high pressure.

  14. Influence of reaction parameters on the hydrogenolysis of hydroxymatairesinol over carbon nanofibre supported palladium catalysts

    OpenAIRE

    Bernas, H.; Plomp, A.J.; Bitter, J.H.; Murzin, D.Y.

    2008-01-01

    The influence of catalyst particle size, stirring rate, catalyst mass (0.2–0.6 g), reaction temperature (60–70 C), and reactant concentration (1.3–4 mmol/L, with constant reactant/catalyst ratio) on the hydrogenolysis of the lignan hydroxymatairesinol (HMR) to matairesinol (MAT) was studied under hydrogen atmosphere using a carbon nanofibre supported palladium catalyst. When the temperature or HMR concentration was increased, the reaction rate increased as expected. However, the reaction rate...

  15. Elemental release from CoCr and NiCr alloys containing palladium.

    Science.gov (United States)

    Beck, Kelly A; Sarantopoulos, Demetrios M; Kawashima, Isao; Berzins, David W

    2012-02-01

    An entirely new subclass of casting alloy composition whereby palladium (∼approximately 25 wt%) is added to traditional base metal alloys such as CoCr and NiCr was recently introduced to the market. The purpose of this study was to evaluate the elemental release of new CoPdCr and NiPdCr alloys and compare them to traditional CoCr and NiCr alloys. Five casting alloys were investigated: CoPdCr-A (NobleCrown NF, The Argen Corporation), CoPdCr-I (Callisto CP+, Ivoclar Vivadent), NiPdCr (NobleCrown, Argen), CoCr (Argeloy N.P. Special, Argen), and NiCr (Argeloy N.P. Star, Argen). Rectangular specimens (n = 6/alloy) were prepared and immersed in a lactic acid/NaCl solution at 37°C for 7 days according to ISO 10271. Solutions were analyzed with ICP-AES to determine elemental release. The concentrations of major ions (cobalt, nickel, palladium, chromium, and molybdenum) were compared using a generalized linear model (p alloys released a significantly greater amount of respective ions (Co, Cr, Mo, and total ions) compared to the traditional CoCr alloy. No significant differences in elemental release were noted between NiPdCr and NiCr. Optical microscopic examination showed abundant areas of corrosion in the palladium-containing CoCr alloys after immersion, whereas little difference was observed for the other alloys. Corrosion resistance measured via elemental release was compromised when CoCr was alloyed with palladium, but this effect was not observed with NiCr. © 2011 by the American College of Prosthodontists.

  16. Palladium-catalysed direct cross-coupling of organolithium reagents with aryl and vinyl triflates.

    Science.gov (United States)

    Vila, Carlos; Hornillos, Valentín; Giannerini, Massimo; Fañanás-Mastral, Martín; Feringa, Ben L

    2014-10-06

    A palladium-catalysed cross-coupling of organolithium reagents with aryl and vinyl triflates is presented. The reaction proceeds at 50 or 70 °C with short reaction times, and the corresponding products are obtained with moderate to high yields, with a variety of alkyl and (hetero)aryl lithium reagents. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Palladium-catalyzed, asymmetric Baeyer–Villiger oxidation of prochiral cyclobutanones with PHOX ligands

    KAUST Repository

    Petersen, Kimberly S.

    2011-06-01

    Described in this report is a general method for the conversion of prochiral 3-substituted cyclobutanones to enantioenriched γ-lactones through a palladium-catalyzed Baeyer-Villiger oxidation using phosphinooxazoline ligands in up to 99% yield and 81% ee. Lactones of enantiopurity ≥93% could be obtained through a single recrystallization step. Importantly, 3,3-disubtituted cyclobutanones produced enantioenriched lactones containing a β-quaternary center. © 2011 Elsevier Ltd. All rights reserved.

  18. Synthesis, Characterization, and Biological Activity of Nickel (II) and Palladium (II) Complex with Pyrrolidine Dithiocarbamate (PDTC)

    OpenAIRE

    Sk Imadul Islam; Suvendu Bikash Das; Sutapa Chakrabarty; Sudeshna Hazra; Akhil Pandey; Animesh Patra

    2016-01-01

    The synthesis of square planar Ni(II) and Pd(II) complexes with pyrrolidine dithiocarbamate (PDTC) was characterized by elemental, physiochemical, and spectroscopic methods. Two complexes were prepared by the reaction of nickel acetate and palladium acetate with pyrrolidine dithiocarbamate (PDTC) in 1 : 2 molar ratio. The bovine serum albumin (BSA) interaction with complexes was examined by absorption and fluorescence spectroscopic techniques at pH 7.4. All the spectral data suggest that coor...

  19. Palladium-Catalyzed One-Pot Approach to 3-(Diarylmethyleneoxindoles from Propiolamidoaryl Triflate

    Directory of Open Access Journals (Sweden)

    Dahye Lee

    2015-08-01

    Full Text Available 3-(Diarylmethyleneoxindoles have been synthesized from propiolamidoaryl triflate utilizing a palladium-catalyzed one-pot reaction consisting of three successive reactions: Sonogashira, Heck, and Suzuki-Miyaura. This method allows for the production of a complex skeleton of 3-(diarylmethyleneoxindole from propiolamidoaryl triflate using a commercially available aryl iodide and arylboronic acid in a simple and efficient way with moderate yield and stereoselectivity.

  20. Ultrasound agitated phytofabrication of palladium nanoparticles using Andean blackberry leaf and its photocatalytic activity

    OpenAIRE

    Kumar, Brajesh; Smita, Kumari; Cumbal, Luis; Debut, Alexis

    2015-01-01

    In this report, ultrasonication and Andean blackberry leaf extract are employed for the fabrication of palladium nanoparticles (PdNPs); and further evaluated its photocatalytic activity against methylene blue (MB). The as-synthesized PdNPs were characterized using UV–visible spectroscopy, transmission electron microscopy (TEM), Dynamic light scattering (DLS) and X-ray diffraction (XRD). TEM analysis demonstrated the formation of decahedron shape PdNPs with a diameter of 55–60 nm and XRD confi...

  1. Is spillover relevant for hydrogen adsorption and storage in porous carbons doped with palladium nanoparticles?

    OpenAIRE

    Blanco-Rey, María; Juaristi, J. Iñaki; Alducin, Maite; López, María J.; Alonso Martín, Julio Alfonso

    2016-01-01

    Producción Científica Experiments have shown that the efficiency of nanoporous carbons to store hydrogen becomes enhanced by doping the material with metallic nanoparticles. In particular, doping with palladium has been used with success. The hypothesis to justify the enhancement has been that the Pd nanoparticles dissociate the hydrogen molecules and then the hydrogen atoms spill over the carbon substrate, where the hydrogen is retained. To test this hypothesis we have performed ab initio...

  2. Butylphenyl-functionalized palladium nanoparticles as effective catalysts for the electrooxidation of formic acid.

    Science.gov (United States)

    Zhou, Zhi-You; Kang, Xiongwu; Song, Yang; Chen, Shaowei

    2011-06-07

    Monodisperse butylphenyl-functionalized palladium (Pd-BP, dia. 2.24 nm) nanoparticles were synthesized through co-reduction of butylphenyldiazonium and H(2)PdCl(4) by NaBH(4). Because of this unique surface functionalization and a high specific electrochemical surface area (122 m(2) g(-1)), the Pd-BP nanoparticles exhibited a mass activity ∼4.5 times that of commercial Pd black for HCOOH electrooxidation.

  3. Ligand effect in enantioselective hydrogenation on skeletal copper-palladium catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Vedenyapin, A.A.; Kuznetsova, T.I.; Klabunovskii, E.I.

    1987-08-10

    In the continuation of the study of the capacity of skeletal Cu-Pd catalysts modified with RR-tartaric acid and containing no more than 5 at.% Pd, to conduct enantioselective hydrogenation of ethylacetoacetate (EAA) into R-ethyl-..beta..-hydroxybutyrate (R-EHB), they studied this phenomenon in more detail and made the previously obtained data more precise. Pronounced synergism of the asymmetric effect of chiral copper-palladium catalysts related to manifestation of a ligand effect was found.

  4. Selective Palladium(II)-Catalyzed Carbonylation of Methylene β-C-H Bonds in Aliphatic Amines.

    Science.gov (United States)

    Cabrera-Pardo, Jaime R; Trowbridge, Aaron; Nappi, Manuel; Ozaki, Kyohei; Gaunt, Matthew J

    2017-09-18

    Palladium(II)-catalyzed C-H carbonylation reactions of methylene C-H bonds in secondary aliphatic amines lead to the formation of trans-disubstituted β-lactams in excellent yields and selectivities. The generality of the C-H carbonylation process is aided by the action of xantphos-based ligands and is important in securing good yields for the β-lactam products. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Development of hydrogen sensors based on fiber Bragg grating with a palladium foil for online dissolved gas analysis in transformers

    Science.gov (United States)

    Fisser, Maximilian; Badcock, Rodney A.; Teal, Paul D.; Swanson, Adam; Hunze, Arvid

    2017-06-01

    Hydrogen evolution, identified by dissolved gas analysis (DGA), is commonly used for fault detection in oil immersed electrical power equipment. Palladium (Pd) is often used as a sensing material due to its high hydrogen absorption capacity and related change in physical properties. Hydrogen is absorbed by Pd causing an expansion of the lattice. The solubility, and therefore lattice expansion, increases with increasing partial pressure of hydrogen and decreasing temperature. As long as a phase change is avoided the expansion is reversible and can be utilized to transfer strain into a sensing element. Fiber Bragg gratings (FBG) are a well-established optical fiber sensor (OFS), mainly used for temperature and strain sensing. A safe, inexpensive, reliable and precise hydrogen sensor can be constructed using an FBG strain sensor to transduce the volumetric expansion of Pd due to hydrogen absorption. This paper reports on the development, and evaluation, of an FBG gas sensing OFS and long term measurements of dissolved hydrogen in transformer mineral oil. We investigate the effects of Pd foil cross-section and strain transfer between foil and fiber on the sensitivity of the OFS. Two types of Pd metal sensors were manufactured using modified Pd foil with 20 and 100 μm thickness. The sensors were tested in transformer oil at 90°C and a hydrogen concentration range from 20- 3200 ppm.

  6. Novel phenol biosensor based on laccase immobilized on reduced graphene oxide supported palladium-copper alloyed nanocages.

    Science.gov (United States)

    Mei, Li-Ping; Feng, Jiu-Ju; Wu, Liang; Zhou, Jia-Ying; Chen, Jian-Rong; Wang, Ai-Jun

    2015-12-15

    Developing new nanomaterials is of key importance to improve the analytical performances of electrochemical biosensors. In this work, palladium-copper alloyed nanocages supported on reduced graphene oxide (RGO-PdCu NCs) were facilely prepared by a simple one-pot solvothermal method. A novel phenol biosensor based on laccase has been constructed for rapid detection of catachol, using RGO-PdCu NCs as electrode material. The as-developed phenol biosensor greatly enhanced the electrochemical signals for catechol. Under the optimal conditions, the biosensor has two linear ranges from 0.005 to 1.155 mM and 1.655 to 5.155 mM for catachol detection at 0.6 V, the sensitivity of 12.65 µA mM(-1) and 5.51 µA mM(-1), respectively. This biosensor showed high selectivity, low detection limit, good reproducibility, and high anti-interference ability. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Palladium-Catalyzed, Direct Boronic Acid Synthesis from Aryl Chlorides: A Simplified Route to Diverse Boronate Ester Derivatives

    Science.gov (United States)

    Trice, Sarah L.J.

    2010-01-01

    Although much current research focuses on developing new boron reagents and identifying robust catalytic systems for the cross-coupling of these reagents, the fundamental preparations of the nucleophilic partners (i.e., boronic acids and derivatives) has been studied to a lesser extent. Most current methods to access boronic acids are indirect and require harsh conditions or expensive reagents. A simple and efficient palladium-catalyzed, direct synthesis of arylboronic acids from the corresponding aryl chlorides using an underutilized reagent, tetrahydroxydiboron B2(OH)4, is reported. To insure preservation of the carbon-boron bond, the boronic acids were efficiently converted to the trifluoroborate derivatives in good to excellent yields without the use of a work-up or isolation. Further, the intermediate boronic acids can be easily converted to a wide range of useful boronates. Finally, a two-step, one-pot method was developed to couple two aryl chlorides efficiently in a Suzuki-Miyaura-type reaction. PMID:21105666

  8. Microwave Deposition of Palladium Catalysts on Graphite Spheres and Reduced Graphene Oxide Sheets for Electrochemical Glucose Sensing

    Directory of Open Access Journals (Sweden)

    Jian-De Xie

    2017-09-01

    Full Text Available This work outlines a synthetic strategy inducing the microwave-assisted synthesis of palladium (Pd nanocrystals on a graphite sphere (GS and reduced graphene oxide (rGO supports, forming the Pd catalysts for non-enzymatic glucose oxidation reaction (GOR. The pulse microwave approach takes a short period (i.e., 10 min to fast synthesize Pd nanocrystals onto a carbon support at 150 °C. The selection of carbon support plays a crucial role in affecting Pd particle size and dispersion uniformity. The robust design of Pd-rGO catalyst electrode displays an enhanced electrocatalytic activity and sensitivity toward GOR. The enhanced performance is mainly attributed to the synergetic effect that combines small crystalline size and two-dimensional conductive support, imparting high accessibility to non-enzymatic GOR. The rGO sheets serve as a conductive scaffold, capable of fast conducting electron. The linear plot of current response versus glucose concentration exhibits good correlations within the range of 1–12 mM. The sensitivity of the Pd-rGO catalyst is significantly enhanced by 3.7 times, as compared to the Pd-GS catalyst. Accordingly, the Pd-rGO catalyst electrode can be considered as a potential candidate for non-enzymatic glucose biosensor.

  9. Microwave Deposition of Palladium Catalysts on Graphite Spheres and Reduced Graphene Oxide Sheets for Electrochemical Glucose Sensing.

    Science.gov (United States)

    Xie, Jian-De; Gu, Siyong; Zhang, Houan

    2017-09-21

    This work outlines a synthetic strategy inducing the microwave-assisted synthesis of palladium (Pd) nanocrystals on a graphite sphere (GS) and reduced graphene oxide (rGO) supports, forming the Pd catalysts for non-enzymatic glucose oxidation reaction (GOR). The pulse microwave approach takes a short period (i.e., 10 min) to fast synthesize Pd nanocrystals onto a carbon support at 150 °C. The selection of carbon support plays a crucial role in affecting Pd particle size and dispersion uniformity. The robust design of Pd-rGO catalyst electrode displays an enhanced electrocatalytic activity and sensitivity toward GOR. The enhanced performance is mainly attributed to the synergetic effect that combines small crystalline size and two-dimensional conductive support, imparting high accessibility to non-enzymatic GOR. The rGO sheets serve as a conductive scaffold, capable of fast conducting electron. The linear plot of current response versus glucose concentration exhibits good correlations within the range of 1-12 mM. The sensitivity of the Pd-rGO catalyst is significantly enhanced by 3.7 times, as compared to the Pd-GS catalyst. Accordingly, the Pd-rGO catalyst electrode can be considered as a potential candidate for non-enzymatic glucose biosensor.

  10. The role of Glutathione, Cysteine and D-Penicillamine in exchanging Palladium and Vanadium metals from albumin metal complex.

    Science.gov (United States)

    Mukhtiar, Muhammad; Jan, Syed Umer; Ullah, Ihsan; Hussain, Abid; Ullah, Izhar; Gul, Rahman; Ali, Essa; Jabbar, Abdul; Kuthu, Zulfiqar Hussan; Wasim, Muhammad; Khan, Muhammad Farid

    2017-11-01

    Thiol groups are extensively present across biological systems being found in range of small molecules (e.g. Glutathione, Homo-cysteine) and proteins (e.g. albumin, haemo-globin). Albumin is considered to be a major thiol containing protein present in circulating Plasma. Albumin contains a single thiolate group located at cysteine-34(cys-34) at its active site. Albumin also binds a wide variety of metals and metals complexes at various sites around the protein. Usually heavy metals are preferentially attached with the thiol group of albumin. The binding of heavy metals at cys-34 provides a mechanism by which the residence time of potentially toxic species in the body can be increased. In this research we have assessed the oxidative modification of and metal binding capacity of cys-34 with heavy metals Palladium and Vanadium to investigate the ease with which it is possible to effect disulfide-thiol exchange at this sites/or remove a metal bound at this position. Both the metals were treated with albumin and then the albumin metals (Pd and V) complexes were treated with small thoil molecules like Glutathione, Cysteine and D-Penicillamine. Our finding showed that the albumin thiol group retained the metals with itself by forming some strong bonding with the Thiols group, it is concluded from this finding that if by chance both the metals enter the living system; strongly disturb the chemistry and physiological function of this bio-molecule.

  11. Methanol oxidation reaction on core-shell structured Ruthenium-Palladium nanoparticles: Relationship between structure and electrochemical behavior

    Science.gov (United States)

    Kübler, Markus; Jurzinsky, Tilman; Ziegenbalg, Dirk; Cremers, Carsten

    2018-01-01

    In this work the relationship between structural composition and electrochemical characteristics of Palladium(Pd)-Ruthenium(Ru) nanoparticles during alkaline methanol oxidation reaction is investigated. The comparative study of a standard alloyed and a precisely Ru-core-Pd-shell structured catalyst allows for a distinct investigation of the electronic effect and the bifunctional mechanism. Core-shell catalysts benefit from a strong electronic effect and an efficient Pd utilization. It is found that core-shell nanoparticles are highly active towards methanol oxidation reaction for potentials ≥0.6 V, whereas alloyed catalysts show higher current outputs in the lower potential range. However, differential electrochemical mass spectrometry (DEMS) experiments reveal that the methanol oxidation reaction on core-shell structured catalysts proceeds via the incomplete oxidation pathway yielding formaldehyde, formic acid or methyl formate. Contrary, the alloyed catalyst benefits from the Ru atoms at its surface. Those are found to be responsible for high methanol oxidation activity at lower potentials as well as for complete oxidation of CH3OH to CO2 via the bifunctional mechanism. Based on these findings a new Ru-core-Pd-shell-Ru-terrace catalyst was synthesized, which combines the advantages of the core-shell structure and the alloy. This novel catalyst shows high methanol electrooxidation activity as well as excellent selectivity for the complete oxidation pathway.

  12. Design, Fabrication and Prototype testing of a Chip Integrated Micro PEM Fuel Cell Accumulator combined On-Board Range Extender

    Science.gov (United States)

    Balakrishnan, A.; Mueller, C.; Reinecke, H.

    2014-11-01

    In this work we present the design, fabrication and prototype testing of Chip Integrated Micro PEM Fuel Cell Accumulator (CIμ-PFCA) combined On-Board Range Extender (O-BRE). CIμ-PFCA is silicon based micro-PEM fuel cell system with an integrated hydrogen storage feature (palladium metal hydride), the run time of CIμ-PFCA is dependent on the stored hydrogen, and in order to extend its run time an O-BRE is realized (catalytic hydrolysis of chemical hydride, NaBH4. Combining the CIμ-PFCA and O-BRE on a system level have few important design requirements to be considered; hydrogen regulation, gas -liquid separator between the CIμ-PFCA and the O-RE. The usage of traditional techniques to regulate hydrogen (tubes), gas-liquid phase membranes (porous membrane separators) are less desirable in the micro domain, due to its space constraint. Our approach is to use a passive hydrogen regulation and gas-liquid phase separation concept; to use palladium membrane. Palladium regulates hydrogen by concentration diffusion, and its property to selectively adsorb only hydrogen is used as a passive gas-liquid phase separator. Proof of concept is shown by realizing a prototype system. The system is an assembly of CIμ-PFCA, palladium membrane and the O-BRE. The CIμ-PFCA consist of 2 individually processed silicon chips, copper supported palladium membrane realized by electroplating followed by high temperature annealing process under inter atmosphere and the O-BRE is realized out of a polymer substrate by micromilling process with platinum coated structures, which functions as a catalyst for the hydrolysis of NaBH4. The functionality of the assembled prototype system is demonstrated by the measuring a unit cell (area 1 mm2) when driven by the catalytic hydrolysis of chemical hydride (NaBH4 and the prototype system shows run time more than 15 hours.

  13. The effect of loading palladium on zinc oxide on the photocatalytic degradation of methyl tert-butyl ether (MTBE) in water.

    Science.gov (United States)

    Seddigi, Zaki S; Ahmed, Saleh A; Ansari, Shahid P; Yarkandi, Naeema H; Danish, Ekram; Alkibash, Abdullah Abu; Oteef, Mohammed D Y; Ahmed, Shakeel

    2014-01-01

    A series of heterogeneous catalysts was prepared by doping zinc oxide with different palladium loadings in the range of 0.5%-1.5%. The prepared catalysts were characterized by SEM, TEM and XRD. These catalysts were applied to study the degradation of Methyl tert-Butyl Ether (MTBE). An amount of 100 mg of each of these catalysts was added to an aqueous solution of 100 ppm of MTBE. The resulting mixtures were irradiated with UV light for a period of 5 h. A 99.7% removal of MTBE was achieved in the case of the zinc oxide photocatalyst particles doped with 1% Pd. The photoreaction was found to be a first-order one. © 2014 The American Society of Photobiology.

  14. Hydrodechlorination of Tetrachloromethane over Palladium Catalysts Supported on Mixed MgF₂-MgO Carriers.

    Science.gov (United States)

    Bonarowska, Magdalena; Wojciechowska, Maria; Zieliński, Maciej; Kiderys, Angelika; Zieliński, Michał; Winiarek, Piotr; Karpiński, Zbigniew

    2016-11-25

    Pd/MgO, Pd/MgF₂ and Pd/MgO-MgF₂ catalysts were investigated in the reaction of CCl₄ hydrodechlorination. All the catalysts deactivated in time on stream, but the degree of deactivation varied from catalyst to catalyst. The MgF₂-supported palladium with relatively large metal particles appeared the best catalyst, characterized by good activity and selectivity to C₂-C₅ hydrocarbons. Investigation of post-reaction catalyst samples allowed to find several details associated with the working state of hydrodechlorination catalysts. The role of support acidity was quite complex. On the one hand, a definite, although not very high Lewis acidity of MgF₂ is beneficial for shaping high activity of palladium catalysts. The MgO-MgF₂ support characterized by stronger Lewis acidity than MgF₂ contributes to very good catalytic activity for a relatively long reaction period (~5 h) but subsequent neutralization of stronger acid centers (by coking) eliminates them from the catalyst. On the other hand, the role of acidity evolution, which takes place when basic supports (like MgO) are chlorided during HdCl reactions, is difficult to assess because different events associated with distribution of chlorided support species, leading to partial or even full blocking of the surface of palladium, which plays the role of active component in HdCl reactions.

  15. Palladium-based on-wafer electroluminescence studies of GaN-based LED structures

    Energy Technology Data Exchange (ETDEWEB)

    Salcianu, C.O.; Thrush, E.J.; Humphreys, C.J. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Plumb, R.G. [Centre for Photonic Systems, Department of Engineering, University of Cambridge, Cambridge CB3 0FD (United Kingdom); Boyd, A.R.; Rockenfeller, O.; Schmitz, D.; Heuken, M. [AIXTRON AG, Kackertstr. 15-17, 52072 Aachen (Germany)

    2008-07-01

    Electroluminescence (EL) testing of Light Emitting Diode (LED) structures is usually done at the chip level. Assessing the optical and electrical properties of LED structures at the wafer scale prior to their processing would improve the cost effectiveness of producing LED-lamps. A non-destructive method for studying the luminescence properties of the structure at the wafer-scale is photoluminescence (PL). However, the relationship between the on-wafer PL data and the final device EL can be less than straightforward (Y. H Aliyu et al., Meas. Sci. Technol. 8, 437 (1997)) as the two techniques employ different carrier injection mechanisms. This paper provides an overview of some different techniques in which palladium is used as a contact in order to obtain on-wafer electroluminescence information which could be used to screen wafers prior to processing into final devices. Quick mapping of the electrical and optical characteristics was performed using either palladium needle electrodes directly, or using the latter in conjunction with evaporated palladium contacts to inject both electrons and holes into the active region via the p-type capping layer of the structure. For comparison, indium was also used to make contact to the n-layer so that electrons could be directly injected into that layer. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Mechanistic Aspects of Aryl-Halide Oxidative Addition, Coordination Chemistry, and Ring-Walking by Palladium.

    Science.gov (United States)

    Zenkina, Olena V; Gidron, Ori; Shimon, Linda J W; Iron, Mark A; van der Boom, Milko E

    2015-11-02

    This contribution describes the reactivity of a zero-valent palladium phosphine complex with substrates that contain both an aryl halide moiety and an unsaturated carbon-carbon bond. Although η(2) -coordination of the metal center to a C=C or C≡C unit is kinetically favored, aryl halide bond activation is favored thermodynamically. These quantitative transformations proceed under mild reaction conditions in solution or in the solid state. Kinetic measurements indicate that formation of η(2) -coordination complexes are not nonproductive side-equilibria, but observable (and in several cases even isolated) intermediates en route to aryl halide bond cleavage. At the same time, DFT calculations show that the reaction with palladium may proceed through a dissociation-oxidative addition mechanism rather than through a haptotropic intramolecular process (i.e., ring walking). Furthermore, the transition state involves coordination of a third phosphine to the palladium center, which is lost during the oxidative addition as the C-halide bond is being broken. Interestingly, selective activation of aryl halides has been demonstrated by adding reactive aryl halides to the η(2) -coordination complexes. The product distribution can be controlled by the concentration of the reactants and/or the presence of excess phosphine. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Review on Copper and Palladium Based Catalysts for Methanol Steam Reforming to Produce Hydrogen

    Directory of Open Access Journals (Sweden)

    Xinhai Xu

    2017-06-01

    Full Text Available Methanol steam reforming is a promising technology for producing hydrogen for onboard fuel cell applications. The methanol conversion rate and the contents of hydrogen, carbon monoxide and carbon dioxide in the reformate, significantly depend on the reforming catalyst. Copper-based catalysts and palladium-based catalysts can effectively convert methanol into hydrogen and carbon dioxide. Copper and palladium-based catalysts with different formulations and compositions have been thoroughly investigated in the literature. This work summarized the development of the two groups of catalysts for methanol steam reforming. Interactions between the activity components and the supports as well as the effects of different promoters were discussed. Compositional and morphological characteristics, along with the methanol steam reforming performances of different Cu/ZnO and Pd/ZnO catalysts promoted by Al2O3, CeO2, ZrO2 or other metal oxides, were reviewed and compared. Moreover, the reaction mechanism of methanol steam reforming over the copper based and palladium based catalysts were discussed.

  18. Regenerating titanium ventricular assist device surfaces after gold/palladium coating for scanning electron microscopy.

    Science.gov (United States)

    Achneck, Hardean E; Serpe, Michael J; Jamiolkowski, Ryan M; Eibest, Leslie M; Craig, Stephen L; Lawson, Jeffrey H

    2010-01-01

    Titanium is one of the most commonly used materials for implantable devices in humans. Scanning electron microscopy (SEM) serves as an important tool for imaging titanium surfaces and analyzing cells and other organic matter adhering to titanium implants. However, high-vacuum SEM imaging of a nonconductive sample requires a conductive coating on the surface. A gold/palladium coating is commonly used and to date no method has been described to "clean" such gold/palladium covered surfaces for repeated experiments without etching the titanium itself. This constitutes a major problem with titanium-based implantable devices which are very expensive and thus in short supply. Our objective was to devise a protocol to regenerate titaniumsurfaces after SEM analysis. In a series of experiments, titanium samples from implantable cardiac assist devices were coated with fibronectin, seeded with cells and then coated with gold/palladium for SEM analysis. X-ray photoelectron spectroscopy spectra were obtained before and after five different cleaning protocols. Treatment with aqua regia (a 1:3 solution of concentrated nitric and hydrochloric acid), with or without ozonolysis, followed by sonication in soap solution and sonication in deionized water, allowed regenerating titanium surfaces to their original state. Atomic force microscopy confirmed that the established protocol did not alter the titanium microstructure. The protocol described herein is applicable to almost all titanium surfaces used in biomedical sciences and because of its short exposure time to aqua regia, will likely work for many titanium alloys as well. (c) 2009 Wiley-Liss, Inc.

  19. Practical, economical, and eco-friendly starch-supported palladium catalyst for Suzuki coupling reactions.

    Science.gov (United States)

    Baran, Talat

    2017-06-15

    In catalytic systems, the support materials need to be both eco friendly and low cost as well as having high thermal and chemical stability. In this paper, a novel starch supported palladium catalyst, which had these outstanding properties, was designed and its catalytic activity was evaluated in a Suzuki coupling reaction under microwave heating with solvent-free and mild reaction conditions. The starch supported catalyst gave remarkable reaction yields after only 5min as a result of the coupling reaction of the phenyl boronic acid with 23 different substrates, which are bearing aril bromide, iodide, and chloride. The longevity of the catalyst was also investigated, and the catalyst could be reused for 10 runs. The starch supported Pd(II) catalyst yielded remarkable TON (up to 25,000) and TOF (up to 312,500) values by using a simple, fast and eco-friendly method. In addition, the catalytic performance of the catalyst was tested against different commercial palladium catalysts, and the green starch supported catalyst had excellent selectivity. The catalytic tests showed that the novel starch based palladium catalyst proved to be an economical and practical catalyst for the synthesis of biaryl compounds. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Effect of pH on the spontaneous synthesis of palladium nanoparticles on reduced graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaorui [Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Ooki, Wataru; Kosaka, Yoshinori R.; Okonogi, Akinori [Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Marzun, Galina; Wagener, Philipp; Barcikowski, Stephan [Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitaetsstrasse 7, D-45141 Essen (Germany); NanoEnergieTechnikZentrum (NETZ), University of Duisburg-Essen, Carl-Benz-Strasse 199, D-47057 Duisburg (Germany); Kondo, Takahiro [Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Tsukuba Research Center for Interdisciplinary Materials Science (TIMS) & Center for Integrated Research in Fundamental Science and Engineering (CiRfSE), University of Tsukuba, 1-1-1 Tennodai, 305-8573 (Japan); Nakamura, Junji, E-mail: nakamura@ims.tsukuba.ac.jp [Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Tsukuba Research Center for Interdisciplinary Materials Science (TIMS) & Center for Integrated Research in Fundamental Science and Engineering (CiRfSE), University of Tsukuba, 1-1-1 Tennodai, 305-8573 (Japan)

    2016-12-15

    Highlights: • Palladium metal nanoparticles were spontaneously formed on reduced graphene oxide (rGO) via a redox reaction in H{sub 2}O. • The amount of Pd deposited on rGO was affected by pH. • The amount of oxygen-containing functional groups in rGO was increased with the deposition of palladium. • The importance of redox potential in spontaneous deposition was demonstrated by an experiment with Zn, Ni, Pt, Pd, etc.. • The spontaneous redox deposition method is facile, environmentally friendly, and needs no external reducing agents. - Abstract: Palladium (Pd) nanoparticles were spontaneously deposited on reduced graphene oxide (rGO) without any external reducing agents. The prepared Pd/rGO composites were then characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Spontaneous deposition occurred because of a redox reaction between the Pd precursor and rGO, which involved reduction of bivalent Pd to metallic Pd{sup 0} and oxidation of the sp{sup 2} carbon of rGO to oxygen-containing functional groups. The amount of Pd deposited on rGO varied with pH, and this was attributed to electrostatic interactions between the Pd precursor and rGO based on the results of zeta potential measurements. The importance of the redox reaction in the spontaneous deposition was demonstrated in the experiment with Zn, Ni, Cu, Ag, Pt, Pd, and Au.

  1. Dechlorination of Environmental Contaminants Using a Hybrid Nanocatalyst: Palladium Nanoparticles Supported on Hierarchical Carbon Nanostructures

    Directory of Open Access Journals (Sweden)

    Hema Vijwani

    2012-01-01

    Full Text Available This paper demonstrates the effectiveness of a new type of hybrid nanocatalyst material that combines the high surface area of nanoparticles and nanotubes with the structural robustness and ease of handling larger supports. The hybrid material is made by fabricating palladium nanoparticles on two types of carbon supports: as-received microcellular foam (Foam and foam with carbon nanotubes anchored on the pore walls (CNT/Foam. Catalytic reductive dechlorination of carbon tetrachloride with these materials has been investigated using gas chromatography. It is seen that while both palladium-functionalized carbon supports are highly effective in the degradation of carbon tetrachloride, the rate of degradation is significantly increased with palladium on CNT/Foam. However, there is scope to increase this rate further if the wettability of these structures can be enhanced in the future. Microstructural and spectroscopic analyses of the fresh and used catalysts have been compared which indicates that there is no change in density or surface chemical states of the catalyst after prolonged use in dechlorination test. This implies that these materials can be used repeatedly and hence provide a simple, powerful, and cost-effective approach for dechlorination of water.

  2. 2,3-diaminopyridine functionalized reduced graphene oxide-supported palladium nanoparticles with high activity for electrocatalytic oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Yasmin, Sabina; Joo, Yuri; Jeon, Seungwon, E-mail: swjeon3380@naver.com

    2017-06-01

    Highlights: • Synthesis of 2,3 DAP-rGO/Pd catalyst by electrochemical deposition method. • The ORR performance of 2,3 DAP-rGO/Pd catalyst was evaluated by CV and RRDE. • ORR possess 4-electron pathway with lower H{sub 2}O{sub 2}. • Better anodic fuel tolerance and long term stable than that of commercial Pt/C. - Abstract: The electrochemical deposition of Pd nanoparticles (Pd NPs) on 2,3 diamino pyridine functionalized reduced graphene oxide (2,3 DAP-rGO/Pd) has been investigated for the oxygen reduction reaction (ORR) in alkaline media. First, 2,3 diaminopyridine functionalized graphene oxide (2,3 DAP-rGO) has been synthesized via simple hydrothermal method. Then, palladium is directly incorporated into the 2,3 DAP-rGO by electrochemical deposition method to generate 2,3 DAP-rGO/Pd composites. The as-prepared material 2,3 DAP-rGO/Pd has been characterized by various instrumental methods. The morphological analysis shows the cluster-like Pd nanoparticles are dispersed onto the 2,3 diamino pyridine functionalized reduced graphene oxide (2,3 DAP-rGO). The electrocatalytic activities have been verified using cyclic voltammetry (CV) and hydrodynamic voltammetry and chronoamperometry techniques in 0.1 M KOH electrolyte. The as-synthesized 2,3 DAP-rGO/Pd shows higher catalytic activity toward ORR with more positive onset potential and cathodic current density, superior methanol/ethanol tolerance and excellent stability in alkaline medium. It is also noteworthy that the 2,3 DAP-rGO/Pd exhibits a four-electron transfer pathway for ORR with lower H{sub 2}O{sub 2} yield.

  3. Thick pure palladium film with varied crystal structure electroless deposited from choline chloride–palladium chloride solution without the addition of reductant

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yurong; Li, Wei; Wang, Wenchang [School of Petrochemical Engineering, Key Laboratory of Fine Petrochemicals of Jiangsu Province, Changzhou University, Changzhou 213164 (China); Mitsuzak, Naotoshi [Qualtec Co., Ltd, Osaka 590-0906 (Japan); Bao, Weiliang [Department of Chemistry, Zhejiang University, Hanghzou 310058 (China); Chen, Zhidong, E-mail: chen13775646759@hotmail.com [School of Petrochemical Engineering, Key Laboratory of Fine Petrochemicals of Jiangsu Province, Changzhou University, Changzhou 213164 (China); School of Material Science and Engineering, Jiangsu Key Laboratory of Material Surface Technology, Changzhou University, Changzhou 213164 (China)

    2015-07-01

    Immersion deposition procedure was applied to achieve thick pure palladium films with thickness up to about 3 μm from choline chloride (ChCl)–palladium chloride (PdCl{sub 2}) aqueous solution without addition of reductant at 60 °C. Using X-ray diffraction and scanning electron microscope, it was confirmed that Pd films with different crystal orientations and morphology were obtained just by varying the immersion time, and Pd (111) crystal orientation predominated over other crystal orientations during the initial deposition procedure, while (220) conquered (111) about 45 min later. ChCl performing as a reductant facilitated the growth of thick Pd film free of reductant. The immersion deposition of Pd followed the mechanism of replacement reaction accompanying with autocatalyzed reaction and autocatalyzed reaction predominating over replacement reaction. The results revealed that Pd films prepared from ChCl–PdCl{sub 2} solution had excellent properties on solderability and corrosion resistance. - Highlights: • Thick pure Pd film was obtained from ChCl–PdCl{sub 2} aqueous solution without reductant. • Different crystal orientations and morphology of Pd films were achieved. • Immersion time determined the morphology of Pd films. • The mechanism of sustained deposition of Pd on Ni–P surface was deduced.

  4. Highly catalytic hollow palladium nanoparticles derived from silver@silver-palladium core-shell nanostructures for the oxidation of formic acid

    Science.gov (United States)

    Chen, Dong; Cui, Penglei; He, Hongyan; Liu, Hui; Yang, Jun

    2014-12-01

    Hollow Palladium (hPd) nanoparticles (NPs) are prepared via a simple and mild successive method. Firstly, core-shell NPs with silver (Ag) cores and silver-palladium (Ag-Pd) alloy shells are synthesized in aqueous phase by galvanic replacement reaction (GRR) between Ag NPs and Pd2+ ion precursors. Saturated aqueous sodium chloride (NaCl) solution was then employed to remove the Ag component from the core and shell regions of core-shell Ag@Ag-Pd NPs, resulting in the formation of hPd NPs with shrunk sizes in comparison with their core-shell parents. Specifically, the hPd NPs exhibit superior catalytic activity and durability for catalyzing the oxidation of formic acid, compared with the Pd NPs reduced by NaBH4 in aqueous solution and commercial Pd/C catalyst from Johnson Matthey, mainly due to the large electrochemically active surface areas of the hollow particles. In addition, The Ag component in core-shell Ag@Ag-Pd NPs has an unfavorable influence on catalytic activity of NPs for formic acid oxidation. However, the durability could be improved due to the electron donating effect from Ag to Pd atoms in the core-shell NPs.

  5. A One-Pot Self-Assembly Reaction to Prepare a Supramolecular Palladium(II) Cyclometalated Complex: An Undergraduate Organometallic Laboratory Experiment

    Science.gov (United States)

    Fernandez, Alberto; Lopez-Torres, Margarita; Fernandez, Jesus J.; Vazquez-Garcia, Digna; Vila, Jose M.

    2012-01-01

    A laboratory experiment for students in advanced inorganic chemistry is described. Students prepare palladium(II) cyclometalated complexes. A terdentate [C,N,O] Schiff base ligand is doubly deprotonated upon reaction with palladium(II) acetate in a self-assembly process to give a palladacycle with a characteristic tetranuclear structure. This…

  6. Ligand-free palladium-mediated site-specific protein labeling inside gram-negative bacterial pathogens.

    Science.gov (United States)

    Li, Jie; Lin, Shixian; Wang, Jie; Jia, Shang; Yang, Maiyun; Hao, Ziyang; Zhang, Xiaoyu; Chen, Peng R

    2013-05-15

    Palladium, a key transition metal in advancing modern organic synthesis, mediates diverse chemical conversions including many carbon-carbon bond formation reactions between organic compounds. However, expanding palladium chemistry for conjugation of biomolecules such as proteins, particularly within their native cellular context, is still in its infancy. Here we report the site-specific protein labeling inside pathogenic Gram-negative bacterial cells via a ligand-free palladium-mediated cross-coupling reaction. Two rationally designed pyrrolysine analogues bearing an aliphatic alkyne or an iodophenyl handle were first encoded in different enteric bacteria, which offered two facial handles for palladium-mediated Sonogashira coupling reaction on proteins within these pathogens. A GFP-based bioorthogonal reaction screening system was then developed, allowing evaluation of both the efficiency and the biocompatibilty of various palladium reagents in promoting protein-small molecule conjugation. The identified simple compound-Pd(NO3)2 exhibited high efficiency and biocompatibility for site-specific labeling of proteins in vitro and inside living E. coli cells. This Pd-mediated protein coupling method was further utilized to label and visualize a Type-III Secretion (T3S) toxin-OspF in Shigella cells. Our strategy may be generally applicable for imaging and tracking various virulence proteins within Gram-negative bacterial pathogens.

  7. Recovery of palladium, cesium, and selenium from heavy metal alkali borosilicate glass by combination of heat treatment and leaching processes

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhanglian; Okada, Takashi, E-mail: t-okada@u-fukui.ac.jp; Nishimura, Fumihiro; Yonezawa, Susumu

    2017-06-05

    Highlights: • A separation technique of both noble and less noble metal from glass is studied. • Via reductive heat treatment, 80% of palladium is extracted in liquid bismuth. • Sodium–potassium-rich materials with cesium and selenium are phase separated. • From the materials, over 80% of cesium and selenium are extracted in water. - Abstract: Reductive heat-treatment and leaching process were applied to a simulated lead or bismuth soda-potash-borosilicate glass with palladium, cesium, and selenium to separate these elements. In the reductive heat treatment, palladium is extracted in liquid heavy metal phase generated by the reduction of the heavy metal oxides, whereas cesium and selenium are concentrated in phase separated Na–K-rich materials on the glass surface. From the materials, cesium and selenium can be extracted in water, and the selenium extraction was higher in the treatment of the bismuth containing glass. The chemical forms of palladium in the glass affected the extraction efficiencies of cesium and selenium. Among the examined conditions, in the bismuth glass treatment, the cesium and selenium extraction efficiencies in water were over 80%, and that of palladium in liquid bismuth was over 80%.

  8. Tetradentate N2O2 Chelated Palladium(II Complexes: Synthesis, Characterization, and Catalytic Activity towards Mizoroki-Heck Reaction of Aryl Bromides

    Directory of Open Access Journals (Sweden)

    Siti Kamilah Che Soh

    2013-01-01

    Full Text Available Four air and moisture-stable palladium(II-Schiff base complexes, N,N′-bis(α-methylsalicylidenepropane-1,3-diamine palladium(II (2a, N,N′-bis(4-methyl-α-methylsalicylidenepropane-1,3-diamine palladium(II (2b, N,N′-bis(3,5-di-tert-butylsalicylidenepropane-1,3-diamine palladium(II (2c, and N,N′-bis(4-methoxy-salicylidenepropane-1,3-diamine palladium(II (2d, have been successfully synthesised and characterised by CHN elemental analyses and conventional spectroscopic methods. These complexes were investigated as catalysts in the phosphine-free Mizoroki-Heck cross-coupling reactions of aryl bromides with methyl acrylate.

  9. Hybrid gold single crystals incorporating amino acids

    CERN Document Server

    Chen, Linfeng; Weber, Eva; Fitch, Andy N; Pokroy, Boaz

    2016-01-01

    Composite hybrid gold crystals are of profound interest in various research areas ranging from materials science to biology. Their importance is due to their unique properties and potential implementation, for example in sensing or in bio-nanomedicine. Here we report on the formation of hybrid organic-metal composites via the incorporation of selected amino acids histidine, aspartic acid, serine, glutamine, alanine, cysteine, and selenocystine into the crystal lattice of single crystals of gold. We used electron microscopy, chemical analysis and high-resolution synchrotron powder X ray diffraction to examine these composites. Crystal shape, as well as atomic concentrations of occluded amino acids and their impact on the crystal structure of gold, were determined. Concentration of the incorporated amino acid was highest for cysteine, followed by serine and aspartic acid. Our results indicate that the incorporation process probably occurs through a complex interaction of their individual functional groups with ...

  10. A Conjugated Microporous Polymer for Palladium-Free, Visible Light-Promoted Photocatalytic Stille-Type Coupling Reactions.

    Science.gov (United States)

    Ghasimi, Saman; Bretschneider, Simon A; Huang, Wei; Landfester, Katharina; Zhang, Kai A I

    2017-08-01

    The Stille coupling reaction is a versatile method to mainly form aromatic C-C bonds. However, up to now, the use of palladium catalysts is necessary. Here, a palladium-free and photocatalytic Stille-type coupling reaction of aryl iodides and aryl stannanes catalyzing a conjugated microporous polymer-based phototcatalyst under visible light irradiation at room temperature is reported. The novel coupling reaction mechanism occurs between the photogenerated aryl radical under oxidative destannylation of the aryl stannane, and the electron-activated aryl iodide, resulting into the aromatic C-C bond formation reaction. The visible light-promoted Stille-type coupling reaction using the polymer-based pure organic photocatalyst offers a simple, sustainable, and more economic synthetic pathway toward palladium-free aromatic C-C bond formation.

  11. Nepal CRS project incorporates.

    Science.gov (United States)

    1983-01-01

    The Nepal Contraceptive Retail Sales (CRS) Project, 5 years after lauching product sales in June 1978, incorporated as a private, nonprofit company under Nepalese management. The transition was finalized in August 1983. The Company will work through a cooperative agreement with USAID/Kathmandu to complement the national family planning goals as the program continues to provide comtraceptives through retail channels at subsidized prices. Company objectives include: increase contraceptive sales by at least 15% per year; make CRS cost effective and move towards self sufficiency; and explore the possibility of marketing noncontraceptive health products to improve primary health care. After only5 years the program can point to some impressive successes. The number of retial shops selling family planning products increased from 100 in 1978 to over 8000, extending CRS product availability to 66 of the country's 75 districts. Retail sales have climbed dramatically in the 5-year period, from Rs 46,817 in 1978 to Rs 271,039 in 1982. Sales in terms of couple year protection CYP) have grown to 24,451 CYP(1982), a 36% increase over 1980 CYP. Since the beginning of the CRS marketing program, total distribution of contraceptives--through both CRS and the Family Planning Maternal and Child Haelth (FP/MCH) Project--has been increasing. While the FP/MCH program remains the largest distributor,contribution of CRS Products is increasing, indicating that CRS is creating new product acceptors. CRS market share in 1982 was 43% for condoms and 16% for oral contraceptives (OCs). CRS markets 5 products which are subsidized in order to be affordable to consumers as well as attractive to sellers. The initial products launched in June 1978 were Gulaf standard dose OCs and Dhaal lubricated colored condoms. A less expensive lubricates, plain Suki-Dhaal condom was introduced in June 1980 in an attempt to reach poorer rural populations, but rural distribution costs are excessive and Suki

  12. Tracing metal-silicate segregation and late veneer in the Earth and the ureilite parent body with palladium stable isotopes

    Science.gov (United States)

    Creech, J. B.; Moynier, F.; Bizzarro, M.

    2017-11-01

    Stable isotope studies of highly siderophile elements (HSE) have the potential to yield valuable insights into a range of geological processes. In particular, the strong partitioning of these elements into metal over silicates may lead to stable isotope fractionation during metal-silicate segregation, making them sensitive tracers of planetary differentiation processes. We present the first techniques for the precise determination of palladium stable isotopes by MC-ICPMS using a 106Pd-110Pd double-spike to correct for instrumental mass fractionation. Results are expressed as the per mil (‰) difference in the 106Pd/105Pd ratio (δ106Pd) relative to an in-house solution standard (Pd_IPGP) in the absence of a certified Pd isotopic standard. Repeated analyses of the Pd isotopic composition of the chondrite Allende demonstrate the external reproducibility of the technique of ±0.032‰ on δ106Pd. Using these techniques, we have analysed Pd stable isotopes from a range of terrestrial and extraterrestrial samples. We find that chondrites define a mean δ106Pdchondrite = -0.19 ± 0.05‰. Ureilites reveal a weak trend towards heavier δ106Pd with decreasing Pd content, similar to recent findings based on Pt stable isotopes (Creech et al., 2017), although fractionation of Pd isotopes is significantly less than for Pt, possibly related to its weaker metal-silicate partitioning behaviour and the limited field shift effect. Terrestrial mantle samples have a mean δ106Pdmantle = -0.182 ± 0.130‰, which is consistent with a late-veneer of chondritic material after core formation.

  13. Antibiofilm effect enhanced by modification of 1,2,3-triazole and palladium nanoparticles on polysulfone membranes

    KAUST Repository

    Cheng, Hong

    2015-08-01

    Biofouling impedes the performance of membrane bioreactors. In this study, we investigated the antifouling effects of polysulfone membranes that were modified by 1,2,3-triazole and palladium nanoparticles. The membranes to be tested were embedded within a drip flow biofilm reactor, and Pseudomonas aeruginosa PAO1 was inoculated and allowed to establish biofilm on the tested membranes. It was found that 1,2,3-triazole and palladium nanoparticles can inhibit the bacterial growth in aerobic and anaerobic conditions. The decrease in bacterial growth was observed along with a decrease in the amount of total polysaccharide and Pel polysaccharide within the biofilm matrix but not the protein content.

  14. Natural phosphate-supported palladium: A highly efficient and recyclable catalyst for the suzuki-miyaura coupling under microwave irradiation

    KAUST Repository

    Hassine, Ayoub

    2015-01-19

    This report explores Suzuki-Miyaura coupling under microwave irradiation, using a new generation of catalyst that is based on natural phosphate (NP) impregnated by palladium. This catalyst was prepared by the treatment of natural phosphate with bis(benzonitrile)palladium(II) chloride in acetone at room temperature. The catalyst displayed high catalytic activity for the Suzuki-Miyaura coupling of aryl bromides and chlorides with aryl boronic acids in pure water and with the use of microwave irradiation. The low-cost and availability of the solid support, mild reaction conditions, high yields of desired products, recyclability of the catalyst and short reaction times are the notable features of these methods.

  15. A tandem Mannich addition–palladium catalyzed ring-closing route toward 4-substituted-3(2H-furanones

    Directory of Open Access Journals (Sweden)

    Jubi John

    2014-06-01

    Full Text Available A facile route towards highly functionalized 3(2H-furanones via a sequential Mannich addition–palladium catalyzed ring closing has been elaborated. The reaction of 4-chloroacetoacetate esters with imines derived from aliphatic and aromatic aldehydes under palladium catalysis afforded 4-substituted furanones in good to excellent yields. 4-Hydrazino-3(2H-furanones could also be synthesized from diazo esters in excellent yields by utilising the developed strategy. We could also efficiently transform the substituted furanones to aza-prostaglandin analogues.

  16. Catalytic Enantioselective Alkylation of β-Keto Esters with Xanthydrol in the Presence of Chiral Palladium Complex

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyu Yeon; Kim, Dae Young [Soonchunhyang Univ., Asan (Korea, Republic of)

    2016-01-15

    Our research interest has been directed toward the development of synthetic methods for the enantioselective construction of stereogenic carbon centers. Recently, we explored the catalytic enantioselective functionalization of active methines in the presence of chiral palladium(II) complexes. In conclusion, we have accomplished the efficient catalytic enantioselective alkylation of β-keto esters 1 with xanthydrol 2 with high yields and excellent enantioselectivity (up to 98% ee). It should be noted that this alkyaltion reaction proceeds well using air- and moisture-stable chiral palladium com- plexes with low loading (1 mol%)

  17. Palladium on Nitrogen-Doped Mesoporous Carbon: A Bifunctional Catalyst for Formate-Based, Carbon-Neutral Hydrogen Storage.

    Science.gov (United States)

    Wang, Fanan; Xu, Jinming; Shao, Xianzhao; Su, Xiong; Huang, Yanqiang; Zhang, Tao

    2016-02-08

    The lack of safe, efficient, and economical hydrogen storage technologies is a hindrance to the realization of the hydrogen economy. Reported herein is a reversible formate-based carbon-neutral hydrogen storage system that is established over a novel catalyst comprising palladium nanoparticles supported on nitrogen-doped mesoporous carbon. The support was fabricated by a hard template method and nitridated under a flow of ammonia. Detailed analyses demonstrate that this bicarbonate/formate redox equilibrium is promoted by the cooperative role of the doped nitrogen functionalities and the well-dispersed, electron-enriched palladium nanoparticles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Effects of soldering methods on tensile strength of a gold-palladium metal ceramic alloy.

    Science.gov (United States)

    Ghadhanfari, Husain A; Khajah, Hasan M; Monaco, Edward A; Kim, Hyeongil

    2014-10-01

    The tensile strength obtained by conventional postceramic application soldering and laser postceramic welding may require more energy than microwave postceramic soldering, which could provide similar tensile strength values. The purpose of the study was to compare the tensile strength obtained by microwave postceramic soldering, conventional postceramic soldering, and laser postceramic welding. A gold-palladium metal ceramic alloy and gold-based solder were used in this study. Twenty-seven wax specimens were cast in gold-palladium noble metal and divided into 4 groups: laser welding with a specific postfiller noble metal, microwave soldering with a postceramic solder, conventional soldering with the same postceramic solder used in the microwave soldering group, and a nonsectioned control group. All the specimens were heat treated to simulate a normal porcelain sintering sequence. An Instron Universal Testing Machine was used to measure the tensile strength for the 4 groups. The means were analyzed statistically with 1-way ANOVA. The surface and fracture sites of the specimens were subjectively evaluated for fracture type and porosities by using a scanning electron microscope. The mean (standard deviation) ultimate tensile strength values were as follows: nonsectioned control 818 ±30 MPa, microwave 516 ±34 MPa, conventional 454 ±37 MPa, and laser weld 191 ±39 MPa. A 1-way ANOVA showed a significant difference in ultimate tensile strength among the groups (F3,23=334.5; Pgold and palladium noble metals than either conventional soldering or laser welding. Conventional soldering resulted in a higher tensile strength than laser welding. Under the experimental conditions described, either microwave or conventional postceramic soldering would appear to satisfy clinical requirements related to tensile strength. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  19. Catalytic Palladium Film Deposited by Scalable Low-Temperature Aqueous Combustion.

    Science.gov (United States)

    Voskanyan, Albert A; Li, Chi-Ying Vanessa; Chan, Kwong-Yu

    2017-09-27

    This article describes a novel method for depositing a dense, high quality palladium thin film via a one-step aqueous combustion process which can be easily scaled up. Film deposition of Pd from aqueous solutions by conventional chemical or electrochemical methods is inhibited by hydrogen embrittlement, thus resulting in a brittle palladium film. The method outlined in this work allows a direct aqueous solution deposition of a mirror-bright, durable Pd film on substrates including glass and glassy carbon. This simple procedure has many advantages including a very high deposition rate (>10 cm 2 min -1 ) and a relatively low deposition temperature (250 °C), which makes it suitable for large-scale industrial applications. Although preparation of various high-quality oxide films has been successfully accomplished via solution combustion synthesis (SCS) before, this article presents the first report on direct SCS production of a metallic film. The mechanism of Pd film formation is discussed with the identification of a complex formed between palladium nitrate and glycine at low temperature. The catalytic properties and stability of films are successfully tested in alcohol electrooxidation and electrochemical oxygen reduction reaction. It was observed that combustion deposited Pd film on a glassy carbon electrode showed excellent catalytic activity in ethanol oxidation without using any binder or additive. We also report for the first time the concept of a reusable "catalytic flask" as illustrated by the Suzuki-Miyaura cross-coupling reaction. The Pd film uniformly covers the inner walls of the flask and eliminates the catalyst separation step. We believe the innovative concept of a reusable catalytic flask is very promising and has the required features to become a commercial product in the future.

  20. Synthesis, characterization, DFT calculations and antibacterial activity of palladium(II) cyanide complexes with thioamides

    Science.gov (United States)

    Ahmad, Saeed; Nadeem, Shafqat; Anwar, Aneela; Hameed, Abdul; Tirmizi, Syed Ahmed; Zierkiewicz, Wiktor; Abbas, Azhar; Isab, Anvarhusein A.; Alotaibi, Mshari A.

    2017-08-01

    Palladium(II) cyanide complexes of thioamides (or thiones) having the general formula PdL2(CN)2, where L = Thiourea (Tu), Methylthiourea (Metu), N,N‧-Dimethylthiourea (Dmtu), Tetramethylthiourea (Tmtu), 2-Mercaptopyridine (Mpy) and 2-Mercaptopyrimidine (Mpm) were prepared by reacting K2[PdCl4] with potassium cyanide and thioamides in the molar ratio of 1:2:2. The complexes were characterized by elemental analysis, thermal and spectroscopic methods (IR, 1H and 13C NMR). The structures of three of the complexes were predicted by DFT calculations. The appearance of a band around 2100 cm-1 in IR and resonances around 120-130 ppm in the 13C NMR spectra indicated the coordination of cyanide to palladium(II). More than one resonances were observed for CN- carbon atoms in 13C NMR indicating the existence of equilibrium between different species in solution. DFT calculations revealed that in the case of the palladium(II) complex of Tmtu, the ionic dinuclear [Pd(Tmtu)4][Pd(CN)4] form was more stable than the dimer of mononuclear complex [Pd(Tmtu)2(CN)2] by 0.91 kcal mol-1, while for the complexes of Tu or Mpy ligands, the nonionic [Pd(L)2(CN)2] forms were more stable than the corresponding [Pd(L)4][Pd(CN)4] complexes by 1.26 and 6.49 kcal mol-1 for L = Tu and Mpy, respectively. The complexes were screened for antibacterial effects and some of them showed significant activities against both gram positive as well as gram negative bacteria.

  1. Corrosion behavior of silver-palladium dental casting alloys in artificial saliva

    Science.gov (United States)

    Krajewski, Katherine Mary

    Ag-Pd dental casting alloys have been used as alternatives to high gold alloys in restorative dentistry since the 1980s. These alloys exhibited mechanical properties superior to gold alloys and excellent adherence to porcelain in porcelain fused to metal (PFM) restorations, such as dental crowns. However, later increases in the price of palladium along with concerns regarding possible allergic reactions and palladium's cytotoxicity have limited the use of these alloys. Evaluation of the biocompatibility concern requires a better understanding of the interaction of Ag-Pd alloys with the oral environment, and the cost problem would be lessened if the palladium content could be reduced without lowering the corrosion resistance. Previous studies have shown differences in the corrosion behavior between Pd-rich and Ag-rich alloys, but the mechanisms of the two behaviors are not well understood. The purpose of this study was to characterize the electrochemical behavior of binary Ag-Pd alloys under conditions simulating the exposure in the oral cavity. Electrochemical measurements, surface and solution analysis were performed with alloy composition, electrolyte composition, and exposure time as variables. Results showed the corrosion behavior for all alloys was governed by the formation of an insoluble thiocyanate salt combined with selective dissolution of Ag for the Pd-rich alloys. The tendency to form thiocyanate was found to dominate over the tendency to form chloride, the formation of which was suggested in other studies. The electrode behavior has been explained on the basis of the theory of behavior of electrodes of the second kind. The difference in behavior of Ag-rich and Pd-rich alloys has been related to the difference in the solubility of the salts and difference in bonding of thiocyanate with Pd and Ag.

  2. Selective photoionization of palladium isotopes using a two-step excitation scheme

    Science.gov (United States)

    Locke, Clayton R.; Kobayashi, Tohru; Fujiwara, Takashige; Midorikawa, Katsumi

    2017-09-01

    We present a novel two-step even-odd mass isotope selective excitation and ionization scheme, potentially applicable in resource recycling and management of palladium occurring in high-level nuclear waste. In contrast to the conventional three-step selective ionization process, the two-step scheme utilizes transition selection rules to an autoionizing Rydberg state, rather than to an intermediate state, resulting in an increase in efficiency of over an order of magnitude while retaining excellent selectivity of >99.7%. The reduction in the number of excitation lasers required allows several technical simplifications and reduces costs should the process be developed for large-scale resource recycling operations.

  3. Palladium catalyst system comprising zwitterion and/or acid-​functionalized ionic liquid

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention concerns a catalyst system in particular a catalyst system comprising Palladium (Pd), a zwitterion and/or an acid-functionalized ionic liquid, and one or more phosphine ligands, wherein the Pd catalyst can be provided by a complex precursor, such as Pd(CH3COO)2, PdCI2, Pd(CH3...... methyl methacrylate and/or methacrylic acid. Catalyst systems according to the invention are suitable for reactions forming separable product and catalyst phases and supported ionic liquid phase SILP applications....

  4. Thermal stability of platinum, palladium and silver films on yttrium-stabilised zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Gesa, E-mail: gesa.beck@physik.uni-augsburg.de [Chair of Resource Strategy, Institute of Physics, University Augsburg, Universitaetsstrasse 1a, 86159 Augsburg (Germany); Bachmann, Christoph [Institute of Physical Chemistry, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 58, 35392 Giessen (Germany); Bretzler, Rita [Research Institute Precious Metals and Metals Chemistry, Katharinenstrasse 17, 73525 Schwaebisch Gmuend (Germany); Kmeth, Ralf [Chair of Resource Strategy, Institute of Physics, University Augsburg, Universitaetsstrasse 1a, 86159 Augsburg (Germany)

    2014-12-31

    Platinum, palladium and silver films with different microstructures have been prepared on differently orientated yttrium-stabilised zirconia (YSZ) substrates by pulsed laser deposition and then annealed at temperatures between 200 °C and 850 °C. Thereby, an influence of the type of metal, of the microstructure of the as-prepared film and of the orientation of the substrate on the annealing behaviour could be determined. The following annealing effects were observed for platinum, palladium and silver films: i) sharpening of the film boundary, ii) smoothing of the film surfaces, iii) sharpening of the texture [thereby: reduction of the fraction of small angle and twin grain boundaries], iv) grain growth and accordingly reduction of the fraction of grains as well as v) grooving at grain boundaries, vi) void formation at the metal|YSZ-interface, vii) hole formation within the films and viii) reduction of the fraction of droplets. In the case of palladium films also ix) oxidation [between 300 °C ≤ T < 750 °C] and stronger de-wetting phenomena than for platinum [with x) waving of the film and xi) island formation at T ≥ 750 °C] have been found. Silver films are not oxidised, but show stronger de-wetting phenomena than platinum and palladium, with xi) island formation and xii) evaporation of the silver at T ≥ 550 °C. Interestingly, silver films on (111) orientated YSZ are thermally much more stable than silver films on the other orientated substrates up to 750 °C. The annealing effects were described by interface, grain boundary and surface energy minimization. - Highlights: • The thermal stability of Pt, Pd and Ag films has been investigated up to 850 °C. • Annealing effects are e.g. reduction of the fraction of twins and island formation. • Pd is also oxidised between 300 °C ≤ T < 750 °C. • Annealing effects depend on type of metal and on its initial microstructure. • Annealing effects depend also on the orientation of substrate.

  5. Hydrogenation catalysts based on complexes of palladium(II) and polyvinylpyridines

    Energy Technology Data Exchange (ETDEWEB)

    Zharmagambetova, A.K.; Mukhamedzhanova, S.G.; Bekturov, E.A.; Saltykov, Yu.P.

    1992-05-20

    Recently methods for producing a new type of catalyst, grafted complexes have been developed. Polymers containing functional groups have been used quite successfully as a substrate in such catalysts. The refinement of the preparative method for metallopolymeric complexes (MPC) is of some importance. By varying the conditions of interaction between the polymers and the metal compounds the catalytic properties of MPC can be improved significantly. In this study the authors have looked at the effect of the preparative conditions for complexes of palladium(II) with poly-2-vinylpyridine (Pd-P2VP) on their catalytic activity in the hydrogenation of 2-propen-1-ol. 13 refs., 3 figs., 1 tab.

  6. Palladium-catalyzed cross-coupling reactions of aryl boronic acids with aryl halides in water.

    Science.gov (United States)

    Wang, Shaoyan; Zhang, Zhiqiang; Hu, Zhizhi; Wang, Yue; Lei, Peng; Chi, Haijun

    2009-01-01

    An efficient Suzuki cross-coupling reaction using a variety of aryl halides in neat water was developed. The Pd-catalyzed reaction between aryl bromides or chlorides and phenyl boronic acids was compatible with various functional groups and affords biphenyls in good to excellent yields without requirement of organic cosolvents. The air stability and solubility in water of the palladium-phosphinous acid complexes were considered to facilitate operation of the coupling reaction and product isolation. The reaction conditions including Pd catalyst selection, temperature, base and catalyst recoverability were also investigated.

  7. Synthesis of dimethyl gloiosiphone a by way of palladium-catalyzed domino cyclization.

    Science.gov (United States)

    Doi, Takayuki; Iijima, Yusuke; Takasaki, Masaru; Takahashi, Takashi

    2007-05-11

    The synthesis of a spiro[4.4]nonane skeleton by the palladium-catalyzed domino cyclization of a linear 7-methylene-2,10-undecadienyl acetate is described. The pi-allylpalladium intermediate underwent intramolecular alkene insertion with high intraannular diastereoselectivity, followed by intramolecular Heck-type cyclization, leading to a spiro[4.4]nonane system. Oxidation of the allylic ether moiety and transformation of the vinyl group to an exo-methylene unit provided 3, which is the known synthetic intermediate of dimethyl gloiosiphone A (2).

  8. Palladium-catalyzed ring-opening reactions of cyclopropanated 7-oxabenzonorbornadiene with alcohols

    Directory of Open Access Journals (Sweden)

    Katrina Tait

    2016-10-01

    Full Text Available Palladium-catalyzed ring-opening reactions of cyclopropanated 7-oxabenzonorbornadiene derivatives using alcohol nucleophiles were investigated. The optimal conditions were found to be 10 mol % PdCl2(CH3CN2 in methanol, offering yields up to 92%. The reaction was successful using primary, secondary and tertiary alcohol nucleophiles and was compatible with a variety of substituents on cyclopropanated oxabenzonorbornadiene. With unsymmetrical C1-substituted cyclopropanated 7-oxabenzonorbornadienes, the regioselectivity of the reaction was excellent, forming only one regioisomer in all cases.

  9. Palladium-catalyzed arylation of enoates with iodobenzene: stereoselective synthesis of trisubstituted olefins

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Talita de A. [Universidade Federal do Rio de Janeiro (UFRJ/LQB), RJ (Brazil). Nucleo de Pesquisas de Produtos Naturais. Laboratorio de Quimica Bioorganica; Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Instituto de Quimica. Interlab; Silva, Alcides J.M. da; Costa, Paulo R.R., E-mail: prrcosta2011@gmail.com [Universidade Federal do Rio de Janeiro (UFRJ/LQB), RJ (Brazil). Nucleo de Pesquisas de Produtos Naturais. Laboratorio de Quimica Bioorganica; Esteves, Pierre M. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Instituto de Quimica. Interlab; Eberlin, Marcos N., E-mail: eberlin@iqm.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Instituto de Quimica. Laboratorio ThoMSon de Espectrometria de Massas; Vaz, Boniek G. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Instituto de Quimica. Laboratorio ThoMSon de Espectrometria de Massas; Universidade Federal de Goias (UFGO), Goiania, GO (Brazil). Instituto de QuImica

    2013-03-15

    The Heck reaction between E- and Z-enoates and iodobenzene was studied in the presence of Pd(OAc){sub 2}. The stereochemistry in resulting adducts was dependent on the enoate geometry (stereospecific reaction). Best yields were obtained from Z-isomers in acetone using Ag{sub 2} CO{sub 3} as base. The main cationic palladium intermediates possibly involved in the catalytic cycle could be intercepted and characterized by electrospray ionization mass spectrometry (ESI-MS). The stereoselectivity observed was rationalized through the classic mechanism of the Heck reaction. (author)

  10. Oleylamine-functionalized palladium nanoparticles with enhanced electrocatalytic activity for the oxygen reduction reaction

    Science.gov (United States)

    Shi, Yi; Yin, Shengkang; Ma, Yanrong; Lu, Dingkun; Chen, Yu; Tang, Yawen; Lu, Tianhong

    2014-01-01

    The oleylamine (OAm)-functionalized Pd nanoparticles (Pd-OAm) have been conveniently synthesized through direct thermal decomposition method of low cost palladium acetate. The morphology, crystalline structure and composition of the Pd-OAm are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Fourier transform infrared (FT-IR) spectroscopy, XPS and zeta potential analysis confirm the successful immobilization of OAm molecules on the Pd nanoparticles surface. The Pd-OAm displays an enhanced electrocatalytic activity and formic acid-tolerant ability for the oxygen reduction reaction (ORR), suggesting a potential application in cathodic catalyst for direct formic acid fuel cells.

  11. Low-Dimensional Palladium Nanostructures for Fast and Reliable Hydrogen Gas Detection

    Directory of Open Access Journals (Sweden)

    Wooyoung Lee

    2011-01-01

    Full Text Available Palladium (Pd has received attention as an ideal hydrogen sensor material due to its properties such as high sensitivity and selectivity to hydrogen gas, fast response, and operability at room temperature. Interestingly, various Pd nanostructures that have been realized by recent developments in nanotechnologies are known to show better performance than bulk Pd. This review highlights the characteristic properties, issues, and their possible solutions of hydrogen sensors based on the low-dimensional Pd nanostructures with more emphasis on Pd thin films and Pd nanowires. The finite size effects, relative strengths and weaknesses of the respective Pd nanostructures are discussed in terms of performance, manufacturability, and practical applicability.

  12. Synthesis of chitosan supported palladium nanoparticles and its catalytic activity towards 2-nitrophenol reduction

    Energy Technology Data Exchange (ETDEWEB)

    Dhanavel, S.; Nivethaa, E. A. K.; Esther, G.; Stephen, A., E-mail: stephen-arum@hotmail.com [Material Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai-25 (India); Narayanan, V. [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai 600 025 (India)

    2016-05-23

    Chitosan supported Palladium nanoparticles were synthesized by a simple cost effective chemical reduction method using NaBH{sub 4}. The prepared nanocomposite was characterized by X-Ray diffraction analysis, FESEM and Energy dispersive spectroscopy analysis of X-rays (EDAX). The catalytic performance of the nanocomposite was evaluated on the reduction of 2-Nitrophenol to the 2-Amino phenol with rate constant 1.08 × 10{sup −3} S{sup −1} by NaBH{sub 4} using Spectrophotometer.

  13. Adhesion promotion between metadent and a high palladium alloy with a pyrolytically fused porcelain opaque layer.

    Science.gov (United States)

    van Putten, M C; Culbertson, B M

    1994-06-01

    Several authors have reported a preference for the use of high palladium alloys in the construction of implant-fixed partial denture (IFPD) substructures. Heat-polymerized polymethyl methacrylate resins (PMMR) are used to secure denture teeth to IFPD substructures. Metadent (Sun Medical Co, Kyoto, Japan), a heat-polymerized PMMR containing 5% 4-methacryloxyethyl trimellitate anhydride (4-META), could possibly improve the overall design of the prosthesis because this resin adheres to resin and ceramic denture teeth and noble metals. However, adhesive bonding between Metadent and elemental palladium has been shown to be poor. The purpose of this study was to evaluate the potential for adhesive bonding between Metadent, titanate primers, and a ceramic layer pyrolytically fused to a high palladium alloy. Five groups of 10 specimens were prepared. A layer of opaque porcelain was baked on all of the specimens under vacuum at 1760 degrees F. The specimens were grouped as follows: (1) Metadent resin processed on ceramic with no primer, (2) Metadent resin with 10% ethyl acetoacetate titanate (DC) processed on ceramic with no primer, (3) Metadent resin with 10% DC processed to ceramic with a 2% tetraisopropyl (TPT) surface primer, (4) 4-Metadent resin with 10% DC processed to ceramic with a 2% isopropyl dimethacryloyl isostearoyl titanate (KR-7) surface primer, and (5) Metadent resin with 10% DC processed to ceramic with a titanium dioxide layer on the opaque and a KR-7 surface primer. The primers were in a methyl methacrylate (MMA) solution. All of the specimens were heat-polymerized under pressure at 212 degrees F for 1 hour. One-half (25) of the specimens (5 from each group) were hydro-thermocycled at 4 degrees C to 55 degrees C, 0.5 minute dwell per bath for 3,000 cycles. All specimens were tested in shear on an MTS Universal machine at cross head speeds of 0.5/mm/min. The results showed adhesion between the resin-ceramic layer in virtually all groups regardless of

  14. Carbon monoxide migratory insertion - A comparison of cationic and neutral palladium(II) complexes

    Energy Technology Data Exchange (ETDEWEB)

    Frankcombe, K.; Cavell, K.J.; Yates, B.F. [University of Tasmania, Hobart, (Australia); Knott, R.B. [Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW (Australia)

    1998-12-31

    With the use of ANSTO`s resources and expertise and with support from AINSE, we have carried out extensive computer modelling on the mechanism of the palladium catalysed carbonylation reaction, a process which is used industrially in the conversion of carbon monoxide into biodegradable polymers. In this project, experimental and theoretical work has focussed on using Pd(II) complexes containing pyridine carboxylate ligands (NC{sub 5}H{sub 4}COO{sup {sub )}} to explore the fundamental mechanistic steps. The results for subsequent steps in the catalytic cycle are presented and their implication for the design of more efficient catalysts are discussed Truncated abstract. 2 figs.

  15. Second and first-derivative spectrophotometry for efficient simultaneous and individual determination of palladium and cobalt using 1-(2-pyridylazo)-2-naphthol in sodium dodecylsulfate micellar media.

    Science.gov (United States)

    Eskandari, Habibollah; Ghanbari Saghseloo, Ali

    2003-11-01

    1-(2-Pyridylazo)-2-naphthol (PAN) has been used for the simultaneous and individual determination of palladium and cobalt at trace levels. PAN complexes of palladium and cobalt at neutral pH form green-color neutral complexes, which are soluble in aqueous SDS micellar media. Under optimum conditions, calibration graphs for individual determinations by zero and first-derivative spectrophotometry, and also for simultaneous determinations by second-derivative spectrophotometry were obtained. A zero-crossing method using second-derivative spectrophotometry at 628 or 578 and 614 nm, respectively, for cobalt and palladium was used for simultaneous determinations. The method is able to determine the cobalt-to-palladium ratio, 5:1 to 1:10 (Wt/Wt), accurately. The accuracy and reproducibility of the determination method for various known amounts of cobalt and palladium in their binary mixtures were tested. The effects of diverse ions on the determination of cobalt and palladium to investigate the selectivity of the method were also studied. The recommended procedures were applied to a synthetic binary alloy, cobalt in vitamin B12 and B-complex ampoules, a Co2O3-Co3O4 laboratorial chemical mixture, some synthetic cobalt-alloy samples, a Pd-charcoal catalyst, and some synthetic palladium alloys.

  16. 3D-Graphene supports for palladium nanoparticles: Effect of micro/macropores on oxygen electroreduction in Anion Exchange Membrane Fuel Cells

    Science.gov (United States)

    Kabir, Sadia; Serov, Alexey; Atanassov, Plamen

    2018-01-01

    Hierarchically structured 3D-Graphene nanosheets as supports for palladium nanoparticles (Pd/3D-GNS) were fabricated using the Sacrificial Support Method. The pore size distribution of the 3D-GNS supports were tuned by utilizing smaller and larger sized sacrificial silica templates, EH5 and L90. Using a combination of Scanning Electron Microscopy (SEM), N2 sorption and Rotating Ring Disc Electrode (RRDE) technique, it was demonstrated that the EH5 and L90 modified 3D-GNS supports had higher percentage of micro- (50 nm), respectively. The templated pores also played a role in enhancing the oxygen reduction reaction (ORR) as well as membrane electrode assembly (MEA) performance of the Pd nanoparticles in comparison to non-porous 2D-GNS supports. Particularly, incorporation of micropores increased peroxide generation at higher potentials whereas presence of macropores increased both limiting current densities and reduce peroxide yields. Integration of the Pd/GNS nanocomposites into a H2/O2 fed Anion Exchange Membrane Fuel Cell (AEMFC) operating at 60 °C also demonstrated the effect of modified porosity on concentration polarization or transport losses at high current densities. This strategy for the tunable synthesis of hierarchically 3D porous graphitized supports offers a platform for developing morphologically modified nanomaterials for energy conversion.

  17. Structure, stability and geochemical role of palladium chloride complexes in hydrothermal fluids

    Science.gov (United States)

    Bazarkina, Elena F.; Pokrovski, Gleb S.; Hazemann, Jean-Louis

    2014-12-01

    In situ X-ray absorption spectroscopy (XANES and EXAFS) was applied to study palladium speciation in model (Na,Li)Cl-HCl-HNO3-HClO4-H2O solutions and to measure the solubility of PdO(s) and PdS(s) in NaCl-HCl-H2O solutions up to 450 °C and 600 bar. In HNO3 and HClO4 solutions, the square planar Pd(H2O)42+ cation with an average Pd-O distance of 2.00 ± 0.01 Å is the dominant form at 30-100 °C. At T > 100 °C, this cation undergoes hydrolysis resulting in Pd precipitation. In (Na,Li)Cl-HCl solutions Pd forms square planar PdCln(H2O)4-n2-n complexes with Pd-O and Pd-Cl distances of 2.00-2.10 and 2.26-2.31 Å, respectively. At 30-250 °C our data are consistent with a mixture of PdCl(H2O)3+, PdCl2(H2O)20(aq), PdCl3(H2O)-, and PdCl42-, but at T > 250 °C PdCl3(H2O)- and PdCl42- become dominant over a wide range of chloride concentration, from ∼0.03 to at least 9 mol/kg H2O. XANES and EXAFS analyses of these species distribution allowed derivation of the stability constant of the reaction PdCl3- + Cl- = PdCl42- from 300 to 450 °C and 600 bar. These results, coupled with in situ PdO(s) and PdS(s) solubility measurements of this study and a revision of thermodynamic data for these solid phases, allowed generation of a self-consistent thermodynamic data set of the system PdS(s)-PdO(s)-PdCl3--PdCl42-. Our data indicate that Pd can be significantly mobilized as chloride complexes only in sulfide-free oxidizing geological settings (e.g., Chudnoe deposits in Russia, Waterberg deposits in South Africa, Jacutinga-type deposits in Brazil). By contrast, at typical pH (4-8), chlorinity (<10-15 wt% NaCl) and H2S contents (0.001-0.1 wt%) of most hydrothermal fluids, the absolute concentration of Pd-Cl complexes is too low to explain Pd enrichment in volcanogenic massive sulfide, modern seafloor sulfide, and porphyry Cu-Au-Mo deposits. Complexes with S-bearing ligands, very likely other than H2S/HS-, such as S3- and other polysulfide anions, are required to account for Pd

  18. Nickel(II) and palladium(II) complexes of azobenzene-containing ligands as dichroic dyes.

    Science.gov (United States)

    Blackburn, Octavia A; Coe, Benjamin J; Fielden, John; Helliwell, Madeleine; McDouall, Joseph J W; Hutchings, Michael G

    2010-10-18

    A large series of complexes has been synthesized with two chelating, Schiff base azobenzene derivatives connected linearly by coordination to a central nickel(II) or palladium(II) ion. These compounds have the general formulas M(II)(OC(6)H(3)-2-CHNR-4-N═NC(6)H(4)-4-CO(2)Et)(2) [M = Ni; R = n-Bu (3c), n-C(6)H(13) (3d), n-C(8)H(17) (3e), n-C(12)H(25) (3f), Ph (3g), OH (3h), C(6)H(4)-4-CO(2)Et (3i). M = Pd; R = i-Pr (4a), t-Bu (4b), n-Bu (4c), n-C(6)H(13) (4d), n-C(8)H(17) (4e), n-C(12)H(25) (4f), Ph (4g)], M(II)[OC(6)H(3)-2-CHN(n-C(8)H(17))-4-N═NC(6)H(4)-4-CO(2)(n-C(8)H(17))](2) [M = Ni (9), Pd (10)], M(II)[OC(6)H(3)-2-CHN(n-C(8)H(17))-4-N═NC(6)H(4)-4-C(6)H(4)-4-O(n-C(7)H(15))](2) [M = Ni (14), Pd (15)], and M(II)[OC(6)H(3)-2-CHN(CMe(2))-4-N═NC(6)H(4)-4-CO(2)Et](2) [M = Ni (17), Pd (18); the CMe(2) groups are connected]. These compounds have been characterized by using various physical techniques including (1)H NMR spectroscopy and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Single-crystal X-ray structures have been obtained for two pro-ligands and five complexes (3e, 4e, 14, 15, and 17). The latter always show a strictly square planar arrangement about the metal center, except for the Ni(II) complex of a salen-like ligand (17). In solution, broadened (1)H NMR signals indicate distortions from square planar geometry for the bis-chelate Ni(II) complexes. Electronic absorption spectroscopy and ZINDO_S (Zerner's intermediate neglect of differential overlap) and TD-DFT (time-dependent density functional theory) calculations show that the lowest energy transition has metal-to-ligand charge-transfer character. The λ(max) of this band lies in the range of 409-434 nm in dichloromethane, and replacing Ni(II) with Pd(II) causes small blue-shifts. Dichroic ratios measured in various liquid crystal hosts show complexation-induced increases with Ni(II), but using Pd(II) has a detrimental effect.

  19. High Permeability Ternary Palladium Alloy Membranes with Improved Sulfur and Halide Tolerances

    Energy Technology Data Exchange (ETDEWEB)

    K. Coulter

    2010-12-31

    The project team consisting of Southwest Research Institute{reg_sign} (SwRI{reg_sign}), Georgia Institute of Technology (GT), the Colorado School of Mines (CSM), TDA Research, and IdaTech LLC was focused on developing a robust, poison-tolerant, hydrogen selective free standing membrane to produce clean hydrogen. The project completed on schedule and on budget with SwRI, GT, CSM, TDA and IdaTech all operating independently and concurrently. GT has developed a robust platform for performing extensive DFT calculations for H in bulk palladium (Pd), binary alloys, and ternary alloys of Pd. Binary alloys investigated included Pd96M4 where M = Li, Na, Mg, Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ag, Cd, In, Sn, Sb, Te, Hf, Ta, W, Re, Os, Ir, Pt, Au, Tl, Pb, Bi, Ce, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu. They have also performed a series of calculations on Pd{sub 70}Cu{sub 26}Ag{sub 4}, Pd{sub 70}Cu{sub 26}Au{sub 4}, Pd{sub 70}Cu{sub 26}Ni{sub 4}, Pd{sub 70}Cu{sub 26}Pt{sub 4}, and Pd{sub 70}Cu{sub 26}Y{sub 4}. SwRI deposited and released over 160 foils of binary and ternary Pd alloys. There was considerable work on characterizing and improving the durability of the deposited foils using new alloy compositions, post annealing and ion bombardment. The 10 and 25 {micro}m thick films were sent to CSM, TDA and IdaTech for characterization and permeation testing. CSM conducted over 60 pure gas permeation tests with SwRI binary and ternary alloy membranes. To date the PdAu and PdAuPt membranes have exhibited the best performance at temperatures in the range of 423-773 C and their performance correlates well with the predictions from GT. TDA completed testing under the Department of Energy (DOE) WGS conditions on over 16 membranes. Of particular interest are the PdAuPt alloys that exhibited only a 20% drop in flux when sulfur was added to the gas mixture and the flux was completely recovered when the sulfur flow was stopped. IdaTech tested binary

  20. Identification of Active Hydrogen Species on Palladium Nanoparticles for an Enhanced Electrocatalytic Hydrodechlorination of 2,4-Dichlorophenol in Water.

    Science.gov (United States)

    Jiang, Guangming; Lan, Mengna; Zhang, Zhiyong; Lv, Xiaoshu; Lou, Zimo; Xu, Xinhua; Dong, Fan; Zhang, Sen

    2017-07-05

    Clarifying hydrogen evolution and identifying the active hydrogen species are crucial to the understanding of the electrocatalytic hydrodechlorination (EHDC) mechanism. Here, monodisperse palladium nanoparticles (Pd NPs) are used as a model catalyst to demonstrate the potential-dependent evolutions of three hydrogen species, including adsorbed atomic hydrogen (H*ads), absorbed atomic hydrogen (H*abs), and molecular hydrogen (H2) on Pd NPs, and then their effect on EHDC of 2,4-dichlorophenol (2,4-DCP). Our results show that H*ads, H*abs, and H2 all emerge at -0.65 V (vs Ag/AgCl) and have increased amounts at more negative potentials, except for H*ads that exhibits a reversed trend with the potential varying from -0.85 to -0.95 V. Overall, the concentrations of these three species evolve in an order of H*abs < H*ads < H2 in the potential range of -0.65 to -0.85 V, H*ads < H*abs < H2 in -0.85 to -1.00 V, and H*ads < H2 < H*abs in -1.00 to -1.10 V. By correlating the evolution of each hydrogen species with 2,4-DCP EHDC kinetics and efficiency, we find that H*ads is the active species, H*abs is inert, while H2 bubbles are detrimental to the EHDC reaction. Accordingly, for an efficient EHDC reaction, a moderate potential is desired to yield sufficient H*ads and limit H2 negative effect. Our work presents a systematic investigation on the reaction mechanism of EHDC on Pd catalysts, which should advance the application of EHDC technology in practical environmental remediation.

  1. Quantitative analysis of trace palladium contamination in solution using electrochemical X-ray fluorescence (EC-XRF).

    Science.gov (United States)

    Ayres, Zoë J; Newton, Mark E; Macpherson, Julie V

    2016-06-07

    The application of electrochemical X-ray fluorescence (EC-XRF), for the detection of palladium (Pd) contamination in a range of solutions containing electrochemically active compounds, present in excess and relevant to the pharmaceutical and food industries, is reported. In EC-XRF, EC is used to electrochemically pre-concentrate metal on an electrode under forced convection conditions, whilst XRF is employed to spectroscopically quantify the amount of metal deposited, which quantitatively correlates with the original metal concentration in solution. Boron doped diamond is used as the electrode due to its very wide cathodic window and the fact that B and C are non-interfering elements for XRF analysis. The effect of several parameters on the Pd XRF signal intensity are explored including: deposition potential (Edep), deposition time (tdep) and Pd(2+) concentration, [Pd(2+)]. Under high deposition potentials (Edep = -1.5 V), the Pd XRF peak intensity varies linearly with both tdep and [Pd(2+)]. Quantification of [Pd(2+)] is demonstrated in the presence of excess acetaminophen (ACM), l-ascorbic acid, caffeine and riboflavin. We show the same Pd XRF signal intensity (for [Pd(2+)] = 1.1 μM and tdep = 325 s) is observed, i.e. same amount of Pd is deposited on the electrode surface, irrespective of whether these redox active molecules are present or absent. For tdep = 900 s we report a limit of detection for [Pd(2+)] of 3.6 ppb (34 nM). Even lower LODs are possible by increasing tdep or by optimising the X-ray source specifically for Pd. The work presented for Pd detection in the presence of ACM, achieves the required detection sensitivity stipulated by international pharmacopeia guidelines.

  2. Synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel for electrochemical detection of dopamine.

    Science.gov (United States)

    Li, Ruiyi; Yang, Tingting; Li, Zaijun; Gu, Zhiguo; Wang, Guangli; Liu, Junkang

    2017-02-15

    Integration of noble metal nanomaterials on graphene nanosheets potentially paves one way to improve their electronic, chemical and electrochemical properties. The study reported synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel composite (Pd@Au/N,S-MGA). The as-prepared composite offers a well-defined three-dimensional architecture with rich of mesopores. The Pd@Au nanoalloys were dispersed on the graphene framework networks and their active sites were fully exposed. The unique structure achieves to ultra high electron/ion conductivity, electrocatalytic activity and structural stability. The sensor based on the Pd@Au/N,S-MGA creates ultrasensitive electrochemical response towards dopamine due to significantly electrochemical synergy between Pd, Au and N,S-MGA. Its differential pulse voltammetric signal linearly increases with the increase of dopamine concentration in the range from 1.0 × 10(-9) M to 4.0 × 10(-5) M with the detection limit of 3.6 × 10(-10) M (S/N = 3). The analytical method provides the advantage of sensitivity, reproducibility, rapidity and long-term stability. It has been successfully applied in the detection of trace dopamine in biological samples. The study also opens a window on the electronic properties of graphene aerogel and metal nanomaterials as well their nanohybrids to meet needs of further applications as nanoelectronics in diagnosis, bioanalysis and catalysis. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Palladium-catalysed telomerisation of isoprene with glycerol and polyethylene glycol: A facile route to new terpene derivatives

    NARCIS (Netherlands)

    Gordillo, A.; Durán Páchon, L.; de Jesus, E.; Rothenberg, G.

    2009-01-01

    We present here the first example of the telomerisation of isoprene with glycerol and polyethylene glycol (PEG-200), opening a facile route to new terpene structures, based on a combination of renewable and petroleum-based feedstocks. The reaction is catalysed by a palladium-carbene complex.

  4. Semisynthetic derivatives of sesquiterpene lactones by palladium-catalyzed arylation of the alpha-methylene-gamma-lactone substructure.

    Science.gov (United States)

    Han, Changho; Barrios, Francis J; Riofski, Mark V; Colby, David A

    2009-09-18

    The palladium-catalyzed arylation of different alpha-methylene-gamma-lactone-containing sesquiterpene lactones was shown to produce E-olefin coupling products selectively in moderate to excellent yields. Biological evaluation of these semisynthetic sesquiterpene lactone derivatives in HeLa cells showed interesting antiproliferative profiles and provided initial structure-activity data.

  5. Reactivity studies of pincer bis-protic N-heterocyclic carbene complexes of platinum and palladium under basic conditions

    Directory of Open Access Journals (Sweden)

    David C. Marelius

    2016-06-01

    Full Text Available Bis-protic N-heterocyclic carbene complexes of platinum and palladium (4 yield dimeric structures 6 when treated with sodium tert-butoxide in CH2Cl2. The use of a more polar solvent (THF and a strong base (LiN(iPr2 gave the lithium chloride adducts monobasic complex 7 or analogous dibasic complex 8.

  6. N-Heterocyclic carbene-palladium(II)-1-methylimidazole complex catalyzed Mizoroki-Heck reaction of aryl chlorides with styrenes

    National Research Council Canada - National Science Library

    Gao, Ting-Ting; Jin, Ai-Ping; Shao, Li-Xiong

    2012-01-01

    A well-defined N-heterocyclic carbene-palladium(II)-1-methylimidazole [NHC-Pd(II)-Im] complex 1 was found to be an effective catalyst for the Mizoroki-Heck reaction of a variety of aryl chlorides with styrenes...

  7. Homeopathic Ligand-Free Palladium as a Catalyst in the Heck Reaction. A Comparison with a Palladacycle

    NARCIS (Netherlands)

    Vries, André H.M. de; Mulders, Jan M.C.A.; Mommers, John H.M.; Henderickx, Huub J.W.; Vries, Johannes G. de

    2003-01-01

    Ligand-free Pd(OAc)2 can be used as a catalyst in the Heck reaction of aryl bromides as long as the amount of catalyst is kept between 0.01 and 0.1 mol %. At higher concentrations palladium black forms and the reaction stops. The actual catalyst is monomeric. Palladacycles merely serve as a source

  8. Homogeneous catalysis for the production of fine chemicals. Palladium- and nickel-catalysed aromatic carbon–carbon bond formation

    NARCIS (Netherlands)

    Tucker, Charles E.; Vries, Johannes G. de

    2002-01-01

    In this article we describe our recent efforts in the area of palladium- and nickel-catalysed aromatic substitution reactions. Main focus is on low cost and low waste production methods. The use of aromatic carboxylic anhydrides in the Heck reaction leads to a waste-free protocol. In addition these

  9. Binding of palladium (II) 5, 10, 15, 20-tetrakis (4-sulfonatophenyl) porphyrin to a lectin for photosensitizer targeted delivery

    Czech Academy of Sciences Publication Activity Database

    Bogoeva, V.; Petrova, L.; Kubát, Pavel

    2015-01-01

    Roč. 153, DEC 2015 (2015), s. 276-280 ISSN 1011-1344 R&D Projects: GA ČR GA13-12496S Institutional support: RVO:61388955 Keywords : palladium porphyrin * concavalin A * fluorescence Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.035, year: 2015

  10. Anion-assisted trans-cis isomerization of palladium(II) phosphine complexes containing acetanilide functionalities through hydrogen bonding interactions.

    Science.gov (United States)

    Lu, Xiao-Xia; Tang, Hau-San; Ko, Chi-Chiu; Wong, Jenny Ka-Yan; Zhu, Nianyong; Yam, Vivian Wing-Wah

    2005-03-28

    The anion-assisted shift of trans-cis isomerization equilibrium of a palladium(II) complex containing acetanilide functionalities brought about by allosteric hydrogen bonding interactions has been established by UV/Vis, 1H NMR, 31P NMR and ESI-MS studies.

  11. Amine-borane assisted synthesis of wavy palladium nanorods on graphene as efficient catalysts for formic acid oxidation.

    Science.gov (United States)

    Du, Cheng; Liao, Yuxiang; Hua, Xing; Luo, Wei; Chen, Shengli; Cheng, Gongzhen

    2014-11-04

    Wavy palladium (Pd) nanorods were obtained by controlled synthesis by using amine-boranes as the reducing agents. Thanks to the unique structure and strong interaction with graphene, the as-synthesized Pd nanorods supported on graphene exhibit much enhanced electrocatalytic activity towards formic acid oxidation as compared with Pd nanoparticles.

  12. Palladium-Catalyzed Cross-Coupling of Silyl Electrophiles with Alkylzinc Halides: A Silyl-Negishi Reaction.

    Science.gov (United States)

    Cinderella, Andrew P; Vulovic, Bojan; Watson, Donald A

    2017-06-14

    We report the first example of a silyl-Negishi reaction between secondary zinc organometallics and silicon electrophiles. This palladium-catalyzed process provides direct access to alkyl silanes. The delicate balance of steric and electronic parameters of the employed DrewPhos ligand is paramount to suppressing isomerization and promoting efficient and selective cross-coupling.

  13. Hydrogen storage studies on palladium-doped carbon materials (AC, CB, CNMs) @ metal-organic framework-5.

    Science.gov (United States)

    Viditha, V; Srilatha, K; Himabindu, V

    2016-05-01

    Metal organic frameworks (MOFs) are a rapidly growing class of porous materials and are considered as best adsorbents for their high surface area and extraordinary porosity. The MOFs are synthesized by using various chemicals like triethylamine, terepthalic acid, zinc acetate dihydrate, chloroform, and dimethylformamide (DMF). Synthesized MOFs are intercalated with palladium/activated carbon, carbon black, and carbon nanomaterials by chemical reduction method for the purpose of enhancing the hydrogen adsorption capacities. We have observed that the palladium doped activated carbon on MOF-5 showed high hydrogen storage capacity. This may be due to the affinity of the palladium toward hydrogen molecule. The samples are characterized by X-ray diffraction, scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analysis. We have observed a clear decrease in the BET surface area and pore volume. The obtained results show a better performance for the synthesized sample. To our best knowledge, no one has reported the work on palladium-doped carbon materials (activated carbon, carbon black, carbon nanomaterials) impregnated to the metal-organic framework-5. We have attempted to synthesize carbon nanomaterials using indigenously fabricated chemical vapor deposition (CVD) unit as a support. We have observed an increase in the hydrogen storage capacities.

  14. Use of “Homeopathic” Ligand-Free Palladium as Catalyst for Aryl-Aryl Coupling Reactions

    NARCIS (Netherlands)

    Alimardanov, Asaf; Schmieder-van de Vondervoort, Lizette; Vries, André H.M. de; Vries, Johannes G. de

    2004-01-01

    We have previously shown that the use of ligand-free palladium employing Pd(OAc)2 as catalyst precursor in the Heck reaction of aryl bromides is possible if low catalyst loadings, typically between 0.01 – 0.1 mol % are used. We have now tested this phenomenon, which we have dubbed “homeopathic”

  15. Palladium-catalyzed carbonylation of yne esters leading to gamma-alkylidene alpha,beta-unsaturated gamma-lactones.

    Science.gov (United States)

    Harada, Yasuyuki; Fukumoto, Yoshiya; Chatani, Naoto

    2005-09-29

    [reaction: see text] The reaction of yne esters with carbon monoxide (1 atm) in the presence of palladium complexes gives bicyclic unsaturated lactone derivatives in good to high yields. The 2-pyridinyloxy group is a good leaving group among leaving groups examined.

  16. Bulky α-diimine palladium complexes: highly efficient for direct C-H bond arylation of heteroarenes under aerobic conditions.

    Science.gov (United States)

    Ouyang, Jia-Sheng; Li, Yan-Fang; Shen, Dong-Sheng; Ke, Zhuofeng; Liu, Feng-Shou

    2016-10-14

    Through the strategy to enhance the bulkiness on both the backbone and the N-aryl moieties, we designed and synthesized a type of bulky α-diimine palladium complex (i.e., {[Ar-N[double bond, length as m-dash]C(R)-C(R)[double bond, length as m-dash]N-Ar]PdCl2, (Ar = 2-benzhydryl-4,6-dimethylphenyl)}, C1, R = H; C2, R = An; C3, R = Ph). The structures of these palladium complexes were well characterized, while C1 and C3 were further characterized by X-ray diffraction. The catalytic performances of the precatalysts were screened for direct C-H bond arylation of heteroarenes. The bidentate N,N-palladium complex C3 with both a backbone and N-aryl bulkiness was found to be a highly efficient precatalyst under aerobic conditions. With a low palladium loading of 0.5-0.1 mol%, a variety of heteroarenes with challenging bulky steric aryl bromides as well as heteroaryl bromides are all applicable for this cross-coupling reaction.

  17. Palladium-Catalyzed Domino Heck/Intermolecular C-H Bond Functionalization: Efficient Synthesis of Alkylated Polyfluoroarene Derivatives.

    Science.gov (United States)

    Wu, Xin-Xing; Chen, Wen-Long; Shen, Yi; Chen, Si; Xu, Peng-Fei; Liang, Yong-Min

    2016-04-15

    An efficient palladium-catalyzed alkylation of electron-deficient polyfluoroarenes is described. The protocol provides a useful and operationally simple access to a broad scope of alkylated polyfluoroarene derivatives in moderate to excellent yields. This also represents the first example of the introduction of a polyfluoroarene structure involving an alkylpalladium(II) intermediate.

  18. Palladium nanoparticles anchored on graphene nanosheets: Methanol, ethanol oxidation reactions and their kinetic studies

    KAUST Repository

    Nagaraju, Doddahalli H.

    2014-12-01

    Palladium nanoparticles decorated graphene (Gra/Pd nanocomposite) was synthesized by simultaneous chemical reduction of graphene oxide and palladium salt in a single step. The negatively charged graphene oxide (GO) facilitates uniform distribution of Pd2+ ions onto its surface. The subsequent reduction by hydrazine hydrate provides well dispersed Pd nanoparticles decorated graphene. Different amount of Pd nanoparticles on graphene was synthesized by changing the volume to weight ratio of GO to PdCl2. X-ray diffraction studies showed FCC lattice of Pd with predominant (1 1 1) plane. SEM and TEM studies revealed that thin graphene nanosheets are decorated by Pd nanoparticles. Raman spectroscopic studies revealed the presence of graphene nanosheets. The electro-catalytic activity of Gra/Pd nanocomposites toward methanol and ethanol oxidation in alkaline medium was evaluated by cyclic voltammetric studies. 1:1 Gra/Pd nanocomposite exhibited good electro-catalytic activity and efficient electron transfer. The kinetics of electron transfer was studied using chronoamperometry. Improved electro-catalytic activity of 1:1 Gra/Pd nanocomposite toward alcohol oxidation makes it as a potential anode for the alcohol fuel cells. © 2014 Elsevier Ltd.

  19. The production of carbon nanofibers and thin films on palladium catalysts from ethylene oxygen mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Jonathan [Los Alamos National Laboratory; Doorn, Stephen [Los Alamos National Laboratory; Atwater, Mark [UNM MECH.ENG.; Leseman, Zayd [UNM MECH.ENG.; Luhrs, Claudia C [UNM ENG.MECH; Diez, Yolanda F [SPAIN; Diaz, Angel M [SPAIN

    2009-01-01

    The characteristics of carbonaceous materials deposited in fuel rich ethylene-oxygen mixtures on three types of palladium: foil, sputtered film, and nanopowder, are reported. It was found that the form of palladium has a dramatic influence on the morphology of the deposited carbon. In particular, on sputtered film and powder, tight 'weaves' of sub-micron filaments formed quickly. In contrast, on foils under identical conditions, the dominant morphology is carbon thin films with basal planes oriented parallel to the substrate surface. Temperature, gas flow rate, reactant flow ratio (C2H4:02), and residence time (position) were found to influence both growth rate and type for all three forms of Pd. X-ray diffraction, high-resolution transmission electron microscopy, temperature-programmed oxidation, and Raman spectroscopy were used to assess the crystallinity of the as-deposited carbon, and it was determined that transmission electron microscopy and x-ray diffraction were the most reliable methods for determining crystallinity. The dependence of growth on reactor position, and the fact that no growth was observed in the absence of oxygen support the postulate that the carbon deposition proceeds by combustion generated radical species.

  20. In situ characterization of hydrogen absorption in nanoporous palladium produced by dealloying

    Directory of Open Access Journals (Sweden)

    Eva-Maria Steyskal

    2016-08-01

    Full Text Available Palladium is a frequently used model system for hydrogen storage. During the past few decades, particular interest was placed on the superior H-absorption properties of nanostructured Pd systems. In the present study nanoporous palladium (np-Pd is produced by electrochemical dealloying, an electrochemical etching process that removes the less noble component from a master alloy. The volume and electrical resistance of np-Pd are investigated in situ upon electrochemical hydrogen loading and unloading. These properties clearly vary upon hydrogen ad- and absorption. During cyclic voltammetry in the hydrogen regime the electrical resistance changes reversibly by almost 10% upon absorbing approximately 5% H/Pd (atomic ratio. By suitable loading procedures, hydrogen concentrations up to almost 60% H/Pd were obtained, along with a sample thickness increase of about 5%. The observed reversible actuation clearly exceeds the values found in the literature, which is most likely due to the unique structure of np-Pd with an extraordinarily high surface-to-volume ratio.

  1. Complete dechlorination of DDE/DDD using magnesium/palladium system.

    Science.gov (United States)

    Gautam, Sumit Kumar; Suresh, Sumathi

    2007-04-01

    Kinetic studies on the dechlorination of 1,1-dichloro-2,2 bis (4,-chlorophenyl) ethane (DDD) and 1,1,dichloro-2,2 bis (4,-chlorophenyl) ethylene (DDE) in 0.05% biosurfactant revealed that the reaction follows second-order kinetics. The rate of reaction was dependent on the presence of acid, initial concentrations of the target compound, and zerovalent magnesium/tetravalent palladium. Gas chromatography-mass spectrometry analyses of DDE dechlorination revealed the formation of a completely dechlorinated hydrocarbon skeleton, with diphenylethane as the end product, thereby implying the removal of all four chlorine atoms of DDE. In the case of DDD, we identified two partially dechlorinated intermediates [namely, 1,1-dichloro-2, 2 bis (phenyl) ethane and 1, chloro-2, 2 bis (phenyl) ethane] and diphenylethane as the end product. On the basis of products formed from DDD dehalogenation, we propose the removal of aryl chlorine atoms as a first step. Our investigation reveals that biosurfactant may be an attractive solubilizing agent for DDT and its residues. The magnesium/palladium system is a promising option because of its high reactivity and ability to achieve complete dechlorination of DDE and DDD.

  2. Palladium was supported on superparamagnetic nanoparticles: A magnetically recoverable catalyst for Heck reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fengwei; Niu, Jianrui; Wang, Haibo; Yang, Honglei; Jin, Jun; Liu, Na; Zhang, Yubin [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Li, Rong, E-mail: liyirong@lzu.edu.cn [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Ma, Jiantai, E-mail: majiantai@lzu.edu.cn [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Palladium-based heterogeneous catalyst was prepared facilely via the co-precipitation method. Black-Right-Pointing-Pointer The particles are nearly spherical in shape with an average size of 20 {+-} 1.0 nm. Black-Right-Pointing-Pointer The developed magnetic catalyst showed high activity for Heck reaction. Black-Right-Pointing-Pointer The catalyst was easily recovered from the reaction mixture with external magnetic field. Black-Right-Pointing-Pointer The catalytic efficiency for Heck reaction remains unaltered even after 6 repeated cycles. -- Abstract: A novel and high-performance palladium-based catalyst for Heck reaction was prepared easily by the co-precipitation method. The catalyst was characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and atomic absorption spectrophotometry (AAS). The catalyst afforded a fast conversion of the 4-bromonitrobenzene to 4-nitrostilbene at a catalyst loading of 5 mol%, and the efficiency of the catalyst remains unaltered even after 6 repeated cycles. The excellent catalytic performance of the Pd/Fe{sub 3}O{sub 4} catalyst might be attributed to the enhanced synergistic effect between Pd nanoparticles and magnetite.

  3. Ethylene Detection Based on Organic Field-Effect Transistors With Porogen and Palladium Particle Receptor Enhancements.

    Science.gov (United States)

    Besar, Kalpana; Dailey, Jennifer; Katz, Howard E

    2017-01-18

    Ethylene sensing is a highly challenging problem for the horticulture industry because of the limited physiochemical reactivity of ethylene. Ethylene plays a very important role in the fruit life cycle and has a significant role in determining the shelf life of fruits. Limited ethylene monitoring capability results in huge losses to the horticulture industry as fruits may spoil before they reach the consumer, or they may not ripen properly. Herein we present a poly(3-hexylthiophene-2,5-diyl) (P3HT)-based organic field effect transistor as a sensing platform for ethylene with sensitivity of 25 ppm V/V. To achieve this response, we used N-(tert-Butoxy-carbonyloxy)-phthalimide and palladium particles as additives to the P3HT film. N-(tert-Butoxy-carbonyloxy)-phthalimide is used to increase the porosity of the P3HT, thereby increasing the overall sensor surface area, whereas the palladium (<1 μm diameter) particles are used as receptors for ethylene molecules in order to further enhance the sensitivity of the sensor platform. Both modifications give statistically significant sensitivity increases over pure P3HT. The sensor response is reversible and is also highly selective for ethylene compared to common solvent vapors.

  4. Activation cross-sections of deuteron induced reactions on natural palladium

    Energy Technology Data Exchange (ETDEWEB)

    Ditroi, F., E-mail: ditroi@atomki.hu [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), 4026 Debrecen (Hungary); Tarkanyi, F.; Takacs, S. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), 4026 Debrecen (Hungary); Hermanne, A. [Cyclotron Laboratory, Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels (Belgium); Ignatyuk, A.V. [Institute of Physics and Power Engineering (IPPE), Obninsk 249020 (Russian Federation); Baba, M. [Cyclotron and Radioisotope Center (CYRIC), Tohoku University, Sendai 980-8578 (Japan)

    2012-01-01

    Highlights: Black-Right-Pointing-Pointer Excitation function measurement of deuteron induced reactions on natural palladium up to 40 MeV. Black-Right-Pointing-Pointer Model code calculations with EMPIRE, ALICE and TALYS. Black-Right-Pointing-Pointer Integral production yield calculation. Black-Right-Pointing-Pointer Thin layer activation (TLA) with the produced isotopes. - Abstract: Activation cross-sections for deuteron induced reactions were measured on natural palladium up to 40 MeV with the activation method using a stacked-foil irradiation technique and high resolution gamma-spectrometry. Excitation functions are reported for the reactions producing the radionuclides {sup 111}Ag, {sup 110m}Ag, {sup 106m}Ag, {sup 105}Ag, {sup 111m}Pd, {sup 109}Pd, {sup 101}Pd, {sup 100}Pd, {sup 105}Rh, {sup 102g}Rh, {sup 101m}Rh, {sup 100}Rh and {sup 99g}Rh. Comparisons with earlier published data and theoretical results of ALICE-IPPE, EMPIRE and the TALYS codes are presented. Calculated yield curves and activity versus depth distributions are also presented for practical applications such as isotope production or thin layer activation.

  5. Synthesis, spectroscopic and radical scavenging studies of palladium(II)-hydrazide complexes

    Science.gov (United States)

    Ain, Qurrat Ul; Ashiq, Uzma; Jamal, Rifat Ara; Mahrooof-Tahir, Mohammad

    2013-11-01

    In present study, a series of palladium(II) complexes with biologically active hydrazide ligands have been synthesized, characterized and screened for their antioxidant (superoxide and DPPH radical scavenging) properties. Spectral studies (FT-IR, EI-mass, 13C and 1H NMR spectroscopy) and physico-chemical measurements including elemental analysis, magnetic susceptibility and conductivity measurements represented square planar structure for all complexes. Substituted and unsubstituted benzohydrazides (1-4) have shown monodentate behavior forming complexes of general formula [PdL2Cl2]. However, pyridinecarbohydrazides (5 and 6) were coordinated in bidentate fashion of [PdLCl2] general formula producing stable five-membered chelate ring. All palladium complexes were found to be considerably more potent inhibitors of DPPH free radical compared to free hydrazides. These complexes are even stronger DPPH scavengers than standard antioxidant propyl gallate. The complexes have also shown good superoxide scavenging ability compared to inactive free hydrazides, however complexes are weaker superoxide scavengers than ascorbic acid, a standard superoxide inhibitor. An interesting structure activity relationship has been evaluated.

  6. Effect of silver and palladium on dye-removal characteristics of anatase-titania nanotubes.

    Science.gov (United States)

    Harsha, N; Ranya, R; Shukla, S; Biju, S; Reddy, M L P; Warrier, K G K

    2011-03-01

    Anatase-titania nanotubes have been synthesized via hydrothermal and surface-modified by depositing silver and palladium via ultraviolet-reduction method. The pure and surface-modified anatase-titania nanotubes have been characterized using the transmission electron microscope, selected-area electron diffraction, X-ray diffraction, diffuse reflectance, photoluminescence, and Fourier transform infrared spectroscope to reveal their average size, structure, and surface-chemistry. The nanotubes have been utilized for the dye-removal application involving the surface-adsorption mechanism under the dark-condition and photocatalytic degradation mechanism under the ultraviolet-radiation exposure. The variation in the dye-concentration during the dye-adsorption and photocatalysis processes has been determined using the ultraviolet-visible absorption spectrophotometer with methylene blue as a model catalytic dye-agent. It has been shown that silver-deposited anatase-titania nanotubes are more effective in enhancing the kinetics of the dye-removal via surface-adsorption and photocatalytic degradation mechanisms relative to the palladium-deposited anatase-titania nanotubes, which has been attributed to the differences in the surface-chemistry of anatase-titania nanotubes induced by the respective metal-deposition.

  7. Do Scarce Precious Metals Equate to Safe Harbor Investments? The Case of Platinum and Palladium

    Directory of Open Access Journals (Sweden)

    John Francis T. Diaz

    2016-01-01

    Full Text Available This research establishes the predictability and safe harbor properties of two scarce precious metals, namely, platinum and palladium. Utilizing their spot prices, the study concludes intermediate memory in the return structures of both precious metals, which implies the instability of platinum and palladium returns’ persistency in the long run. However, both the ARFIMA-FIGARCH and the ARFIMA-FIAPARCH models confirm long-memory properties in the volatility of the two spot prices. The leverage effects phenomenon is not also present based on the ARFIMA-APARCH and ARFIMA-FIAPARCH models, which may possibly conclude the resilience of both precious metals against increased volatility. However, further tests proved that only platinum has a symmetric volatility response to shocks with the presence of negative gamma parameter, which proves that only platinum can be considered a safe harbor investment, because negative and positive shocks have equal effects on their returns and volatilities. Comparing the four models utilized in this study, the combined ARFIMA-FIAPARCH models are the best fitting model to characterize both precious metals’ spot prices.

  8. Photoelectrochemical properties of palladium sulfide (PdS)

    Energy Technology Data Exchange (ETDEWEB)

    Macia, M.D.; Diaz-Chao, P.; Clamagirand, J.; Ares, J.R.; Ferrer, I.J.; Sanchez, C. [UAM, Madrid (Spain). Laboratoria de Materiales de Interes en Energias Renovables

    2010-07-01

    The electrochemical behaviour of PdS films has been studied in 1M Na{sub 2}SO{sub 3} solution. Photoelectrochemical characterization of polycrystalline PdS thin films have been carried out in the potential range -200mV

  9. Resting state and elementary steps of the coupling of aryl halides with thiols catalyzed by alkylbisphosphine complexes of palladium.

    Science.gov (United States)

    Alvaro, Elsa; Hartwig, John F

    2009-06-10

    Detailed mechanistic studies on the coupling of aryl halides with thiols catalyzed by palladium complexes of the alkylbisphosphine ligand CyPF-(t)Bu (1-dicyclohexylphosphino-2-di-tert-butylphosphinoethylferrocene) are reported. The elementary steps that constitute the catalytic cycle, i.e. oxidative addition, transmetalation and reductive elimination, have been studied, and their relative rates are reported. Each of the steps of the catalytic process occurs at temperatures that are much lower than those required for the reactions catalyzed by a combination of palladium precursors and CyPF-(t)Bu. To explain these differences in rates between the catalytic and stoichiometric reactions, studies were conducted to identify the resting state of the catalyst of the reactions catalyzed by a combination of Pd(OAc)(2) and CyPF-(t)Bu, a combination of Pd(dba)(2) and CyPF-(t)Bu, or the likely intermediate Pd(CyPF-(t)Bu)(Ar)(Br). These data show that the major palladium complex in each case lies off of the catalytic cycle. The resting state of the reactions catalyzed by Pd(OAc)(2) and CyPF-(t)Bu was the palladium bis-thiolate complex [Pd(CyPF-(t)Bu)(SR)(2)] (R = alkyl or aryl). The resting state in reactions catalyzed by Pd(2)(dba)(3) and CyPF-(t)Bu was the binuclear complex [Pd(CyPF-(t)Bu)](2)(mu(2),eta(2)-dba) (9). The resting states of reactions of both aromatic and aliphatic thiols catalyzed by [Pd(CyPF-(t)Bu)(p-tolyl)(Br)] (3a) were the hydridopalladium thiolate complexes [Pd(CyPF-(t)Bu)(H)(SR)] (R= alkyl and aryl). All these palladium species have been prepared independently, and the mechanisms by which they enter the catalytic cycle have been examined in detail. These features of the reaction catalyzed by palladium and CyPF-(t)Bu have been compared with those of reactions catalyzed by the alkylbisphosphine DiPPF and Pd(OAc)(2) or Pd(dba)(2). Our data indicate that the resting states of these reactions are similar to each other and that our mechanistic conclusions about

  10. Adsorption, diffusion, and incorporation of Pd in cubic (0 0 1) Cu{sub 3}N: A DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez M, Jairo Arbey, E-mail: jairorodriguez@unal.edu.co [Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Apartado Postal 14, Ensenada Baja California, CP 22800 (Mexico); Grupo de Estudio de Materiales (GEMA), Departamento de Física, Universidad Nacional de Colombia, AA 5997 Bogotá (Colombia); Moreno-Armenta, María Guadalupe, E-mail: moreno@cnyn.unam.mx [Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Apartado Postal 14, Ensenada Baja California, CP 22800 (Mexico); Takeuchi, Noboru, E-mail: takeuchi@cnyn.unam.mx [Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Apartado Postal 14, Ensenada Baja California, CP 22800 (Mexico)

    2013-11-05

    Highlights: •DFT study of structural and Electronic properties of 0 0 1 surface of copper nitride. •Absorption of palladium on the 0 0 1 Cu{sub 3}N surface in different sites. •Incorporation of palladium into the Cu{sub 3}N matrix. •Study of barrier of energy, if an atom of Pd or Cu is incorporated into the Cu{sub 3}N bulk. •The energy barrier results shows that only a small amount of Pd can be accommodated into the Cu{sub 3}N cell. -- Abstract: We have studied the structural properties of the clean (0 0 1) surface of Cu{sub 3}N in the anti-ReO{sub 3} structure (space group Pm3m) using Density Functional Theory (DFT). We found that a small relaxation occurs: the first interlayer distance is contracted by ∼1.4%, while the second one is expanded by 0.55%. We have also investigated the adsorption of Pd on the (0 0 1)-Cu{sub 3}N surface and determined the energy barriers for lateral diffusion in the topmost layer. The incorporation of Pd atoms into the bulk was also considered by calculating adsorption sites and energy barriers. It is found that the most stable configuration corresponds to the Pd atom occupying the center of the cube. To arrive to this site, the atom has to overcome an energy barrier of 0.78 eV. This configuration is more stable than adsorption of the Pd atom on the surface.

  11. A palladium-catalysed multicomponent coupling approach to conjugated poly(1,3-dipoles) and polyheterocycles

    Science.gov (United States)

    Leitch, David C.; Kayser, Laure V.; Han, Zhi-Yong; Siamaki, Ali R.; Keyzer, Evan N.; Gefen, Ashley; Arndtsen, Bruce A.

    2015-06-01

    Conjugated polymers have emerged over the past several decades as key components for a range of applications, including semiconductors, molecular wires, sensors, light switchable transistors and OLEDs. Nevertheless, the construction of many such polymers, especially highly substituted variants, typically involves a multistep synthesis. This can limit the ability to both access and tune polymer structures for desired properties. Here we show an alternative approach to synthesize conjugated materials: a metal-catalysed multicomponent polymerization. This reaction assembles multiple monomer units into a new polymer containing reactive 1,3-dipoles, which can be modified using cycloaddition reactions. In addition to the synthetic ease of this approach, its modularity allows easy adaptation to incorporate a range of desired substituents, all via one-pot reactions.

  12. A palladium-catalysed multicomponent coupling approach to conjugated poly(1,3-dipoles) and polyheterocycles

    Science.gov (United States)

    Leitch, David C.; Kayser, Laure V.; Han, Zhi-Yong; Siamaki, Ali R.; Keyzer, Evan N.; Gefen, Ashley; Arndtsen, Bruce A.

    2015-01-01

    Conjugated polymers have emerged over the past several decades as key components for a range of applications, including semiconductors, molecular wires, sensors, light switchable transistors and OLEDs. Nevertheless, the construction of many such polymers, especially highly substituted variants, typically involves a multistep synthesis. This can limit the ability to both access and tune polymer structures for desired properties. Here we show an alternative approach to synthesize conjugated materials: a metal-catalysed multicomponent polymerization. This reaction assembles multiple monomer units into a new polymer containing reactive 1,3-dipoles, which can be modified using cycloaddition reactions. In addition to the synthetic ease of this approach, its modularity allows easy adaptation to incorporate a range of desired substituents, all via one-pot reactions. PMID:26077769

  13. Real Time,in situ Observation of the Photocatalytic Destruction of Saccharomyces cerevisiae Cells by Palladium-modified Nitrogen-doped Titanium Oxide Thin Film

    National Research Council Canada - National Science Library

    Jingtao Zhang Qi Li Ronghui Li Jian Ku Shang

    2015-01-01

    Palladium-modified nitrogen-doped titanium oxide(TiON/PdO) thin film was synthesized by the ion-beamassisted deposition technique,which enabled a heavy nitrogen doping and the subsequent light absorption extension...

  14. Bimetallic Catalysts Containing Gold and Palladium for Environmentally Important Reactions

    Directory of Open Access Journals (Sweden)

    Ahmad Alshammari

    2016-07-01

    Full Text Available Supported bimetallic nanoparticles (SBN are extensively used as efficient redox catalysts. This kind of catalysis particularly using SBN has attracted immense research interest compared to their parent metals due to their unique physico-chemical properties. The primary objective of this contribution is to provide comprehensive overview about SBN and their application as promising catalysts. The present review contains four sections in total. Section 1 starts with a general introduction, recent progress, and brief summary of the application of SBN as promising catalysts for different applications. Section 2 reviews the preparation and characterization methods of SBN for a wide range of catalytic reactions. Section 3 concentrates on our own results related to the application of SBN in heterogeneous catalysis. In this section, the oxidation of cyclohexane to adipic acid (an eco-friendly and novel approach will be discussed. In addition, the application of bimetallic Pd catalysts for vapor phase toluene acetoxylation in a fixed bed reactor will also be highlighted. Acetoxylation of toluene to benzyl acetate is another green route to synthesize benzyl acetate in one step. Finally, Section 4 describes the summary of the main points and also presents an outlook on the application of SBN as promising catalysts for the production of valuable products.

  15. Coulomb nuclear interference with deuterons in even palladium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, M.R.D.; Rodrigues, C.L.; Borello-Lewin, T.; Horodynski-Matsushigue, L.B.; Duarte, J. L.M. [Sao Paulo Univ., SP (Brazil); Ukita, G.M. [Universidade de Santo Amaro, SP (Brazil). Faculdade de Psicologia

    2004-09-15

    Angular distributions for the inelastic scattering of 13.0 MeV deuterons on {sup 104,106,108,110}Pd were measured with the Sao Paulo Pelletron-Enge-Spectrograph facility in the range of 12{sup 0} {<=}{theta}{sub lab} {<=}64{sup 0}. A Coulomb-Nuclear Interference analysis, employing the Distorted Wave Born Approximation with the Deformed Optical Model as transition potential, under well established global optical parameters, was applied to the first quadrupolar excitations. The values of C = {delta}{sub LC}/{delta}{sub LN}, the ratio of charge to isoscalar deformation lengths, and of ({delta}{sub LN}){sup 2} were extracted through the comparison of experimental and predicted cross section angular distributions. The ratios of reduced charge to isoscalar transition probabilities, B(EL) to B(ISL) respectively, are related to the square of the parameter C and were thus obtained with the advantage of scale uncertainties cancellation. For {sup 104}Pd, and preliminary for {sup 108}Pd, the respective values of C = 1.18(3) and C = 1.13(4) reveal an enhanced contribution of the protons relative to the neutrons to the excitation, while a smaller effect is found for {sup 106}Pd, C = 1.06(3) and for {sup 110}Pd, C 1.07(3), in comparison with the value C 1.00 expected for homogenous collective excitations. (author)

  16. Palladium-Catalyzed Enantioselective C-H Activation of Aliphatic Amines Using Chiral Anionic BINOL-Phosphoric Acid Ligands.

    Science.gov (United States)

    Smalley, Adam P; Cuthbertson, James D; Gaunt, Matthew J

    2017-02-01

    The design of an enantioselective Pd(II)-catalyzed C-H amination reaction is described. The use of a chiral BINOL phosphoric acid ligand enables the conversion of readily available amines into synthetically valuable aziridines in high enantiomeric ratios. The aziridines can be derivatized to afford a range of chiral amine building blocks incorporating motifs readily encountered in pharmaceutically relevant molecules.

  17. Deuterium overloading of palladium wires by means of high power means of high power ms pulsed electrolysis and electromigration : suggestions of phase transition and related excess heat

    Energy Technology Data Exchange (ETDEWEB)

    Celani, F.; Spallone, A.; Tripodi, P.; Petrocchi, A.; Di Gioacchino, D. [INFN, Laboratori Nazionali di Frascati, Rome (Italy); Marini, P.; Di Stefani, V. [EURESIS, Rome (Italy); Pace, S. [Salerno Univ. (Italy). Dip. di Fisica; Mancini, A. [ORIM s.r.l., Macerata (Italy)

    1996-03-01

    A room-temperature hydrogen and deuterium loading of palladium wires by means of pulsed electrolysis and electromigration effect is described. The D/Pd atomic ratio has been measured by means of the dependence of the resistivity upon the D/Pd ratio. Values of the D/Pd ratio up to 0.95 or even higher have been reached in short times. A correlation between an anomalous temperature rise and a resistivity transition of the overloaded palladium clearly appears.

  18. High power {mu}s pulsed electrolysis using palladium wires: evidence for a possible phase transition under deuterium overloaded conditions and related excess heat

    Energy Technology Data Exchange (ETDEWEB)

    Celani, F.; Spallone, A.; Tripodi, P.; Petrocchi, A.; Di Gioacchino, D. [INFN, Laboratori Nazionali di Frascati, Rome (Italy); Marini, P.; Di Stefano, V. [EURESIS, Rome (Italy); Pace, S. [Salerno Univ. (Italy). Dip. di Fisica; Mancini, A. [ORIM s.r.l., Macerata (Italy)

    1995-07-01

    In this paper, an electrolytic experiment aimed at reaching high deuterium concentration gradients in palladium wires, using the electromigration effect, is described. The selection criteria of experimental parameters will be described, show results of the loading and calorimetric measurements. These tests reveal that a high mean value of D/Pd has been reached in a short time and that there is a correlation between an anomalous heat emission and an electric resistivity transition of the overload palladium.

  19. Palladium-Catalyzed C-H Arylation of α,β-Unsaturated Imines: Catalyst-Controlled Synthesis of Enamine and Allylic Amine Derivatives.

    Science.gov (United States)

    Li, Minyan; González-Esguevillas, María; Berritt, Simon; Yang, Xiaodong; Bellomo, Ana; Walsh, Patrick J

    2016-02-18

    A unique chemo- and regioselective α- and γ-arylation of palladium azapentadienyl intermediates is presented. Two distinct catalysts and sets of conditions successfully controlled the regioselectivity of the arylation. These methods provide the first umpolung C-H functionalization of azapentadienyl palladium intermediates and enable the divergent synthesis of allylic amine and enamine derivatives, which are of significant interest in the pharmaceutical industry. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Electrochemical sensor based on palladium-reduced graphene oxide modified with gold nanoparticles for simultaneous determination of acetaminophen and 4-aminophenol.

    Science.gov (United States)

    Wang, Huijuan; Zhang, Siyu; Li, Shufang; Qu, Jianying

    2018-02-01

    Herein, a newly developed electrochemical sensor base on the nanohybrid of palladium-reduced graphene oxide modified with gold nanoparticles (Au/Pd/rGO) was established, which was prepared by electrodeposing Au nanoparticles on Pd/rGO modified on a glass carbon electrode. The morphologies and microstructures of the as-prepared nanohybrid were characterized by X-ray photoelectron spectroscopy, Scanning electron microscopy and Infrared spectroscopy. And, experiment results showed that the prepared Au/Pd/rGO nanohybrid exhibited excellent electrocatalytic- activity toward the redox of acetaminophen (PA) and 4-aminophenol (4-AP) simultaneously. The linear detection ranges were 1.00-250.00μM for PA and 1.00-300.00μM for 4-AP, with the detection limits of 0.30μM for PA and 0.12μM for 4-AP, respectively. Because of the excellent performance of lower detection, wider linear range and better selectivity, the prepared Au/Pd/rGO nanohybrid with more potential applications was a promising candidate for advanced electrode material in electrochemical sensing field. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Access to the meta position of arenes through transition metal catalysed C-H bond functionalisation: a focus on metals other than palladium.

    Science.gov (United States)

    Mihai, Madalina T; Genov, Georgi R; Phipps, Robert J

    2018-01-02

    The elaboration of simple arenes in order to access more complex substitution patterns is a crucial endeavor for synthetic chemists, given the central role that aromatic rings play in all manner of important molecules. Classical methods are now routinely used alongside stoichiometric organometallic approaches and, most recently, transition metal catalysis in the range of methodologies that are available to elaborate arene C-H bonds. Regioselectivity is an important consideration when selecting a method and, of all those available, it is arguably those that target the meta position that are fewest in number. The rapid development of transition metal-catalysed C-H bond functionalisation over the last few decades has opened new possibilities for meta-selective C-H functionalisation through the diverse reactivity of transition metals and their compatibility with a wide range of directing groups. The pace of discovery of such processes has grown rapidly in the last five years in particular and it is the purpose of this review to examine these but in doing so to place the focus on metals other than palladium, the specific contributions of which have been very recently reviewed elsewhere. It is hoped this will serve to highlight to the reader the breadth of current strategies and mechanisms that have been used to tackle this challenge, which may inspire further progress in the field.

  2. Determination of very low levels of gold and palladium in wastewater and soil samples by atomic absorption after preconcentration on modified MCM-48 and MCM-41 silica.

    Science.gov (United States)

    Ebrahimzadeh, H; Tavassoli, N; Amini, M M; Fazaeli, Y; Abedi, H

    2010-06-15

    A simple and rapid method was applied for extraction, preconcentration and determination of trace amounts of gold and palladium in wastewater by using functionalized mesoporous silica. Extraction was investigated on adsorbents prepared by grafting aminopropyl on the surface of MCM-41 and MCM-48 mesoporous silica. The optimum experimental conditions such as pH, flow rates, type and the smallest amount of eluent for elution of Au and Pd, break through volume and the influence of various cationic interferences on the sorption of gold(III) and palladium(II) were evaluated. The extraction efficiency for gold and palladium were greater than 98% and limit of detection (LOD) was lower than 0.06ng mL(-1) for gold and 0.1ng mL(-1) for palladium on both functionalized MCM-41 and MCM-48 silica. The preconcentration factor was greater than 800 for gold and 400 for palladium and the relative standard deviation (RSD) of the method was gold(III) and palladium(II) in some real samples, including wastewater and soil samples.

  3. Effect of hydration on the electrical explosion of a fine palladium wire in a vacuum

    Science.gov (United States)

    Sarkisov, G. S.

    2017-11-01

    Experiments with fast electric explosion of a hydrated palladium wire in vacuum show a significant decrease in Joule deposited energy, expansion rate, and voltage amplitude at breakdown. An increase in the density of diffused hydrogen and oxygen at the wire surface leads to an early generation of plasma due to evaporation impurity and rapid development of avalanche breakdown along the wire surface. The non-hydrated Pd wire demonstrates a longer resistive time, higher voltage peak, greater energy and expansion speed. The decrease in the deposited energy was ˜35%, and the expansion rate was ˜18%. The peak of light emission during voltage breakdown was twice higher for a hydrated Pd wire than for a bare one.

  4. Reduction of Aromatic Hydrocarbons by Zero-Valent Iron and Palladium Catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young-Hun; Shin, Won Sik; Ko, Seok-Oh; Kim, Myung-Chul

    2004-03-31

    Permeable reactive barrier (PRB) is an alternative technology for soil and groundwater remediation. Zero valent iron, which is the most popular PRB material, is only applicable to halogenated aliphatic organics and some heavy metals. The objective of this study was to investigate reductive dechlorination of halogenated compounds and reduction of non-halogenated aromatic hydrocarbons using zero valent metals (ZVMs) and catalysts as reactive materials for PRBs. A group of small aromatic hydrocarbons such as monochlorophenols, phenol and benzene were readily reduced with palladium catalyst and zero valent iron. Poly-aromatic hydrocarbons (PAHs) were also tested with the catalysts and zero valent metal combinations. The aromatic rings were reduced and partly reduced PAHs were found as the daughter compounds. The current study demonstrates reduction of aromatic compounds by ZVMs and modified catalysts and implicates that PRB is applicable not only for halogenated organic compounds but nonhalogenated aromatic compounds such as PAHs.

  5. Radiative lifetimes, branching fractions and oscillator strengths in Pd I and the solar palladium abundance

    Science.gov (United States)

    Xu, H. L.; Sun, Z. W.; Dai, Z. W.; Jiang, Z. K.; Palmeri, P.; Quinet, P.; Biémont, É.

    2006-06-01

    Transition probabilities have been derived for 20 5s-5p transitions of Pd I from a combination of radiative lifetime measurements for 6 odd-parity levels with time-resolved laser-induced fluorescence spectroscopy and of branching fraction determination using a hollow cathode discharge lamp. Additional oscillator strengths for 18 transitions have been determined from measured lifetimes and theoretical branching fractions obtained from configuration interaction calculations with core-polarization effects included. These new results have allowed us to refine the palladium abundance in the solar photosphere: A_Pd = 1.66 ± 0.04, in the usual logarithmic scale, a result in close agreement with the meteoritic value.

  6. Palladium(II)/Brønsted Acid-Catalyzed Enantioselective Oxidative Carbocyclization-Borylation of Enallenes.

    Science.gov (United States)

    Jiang, Tuo; Bartholomeyzik, Teresa; Mazuela, Javier; Willersinn, Jochen; Bäckvall, Jan-E

    2015-05-11

    An enantioselective oxidative carbocyclization-borylation of enallenes that is catalyzed by palladium(II) and a Brønsted acid was developed. Biphenol-type chiral phosphoric acids were superior co-catalysts for inducing the enantioselective cyclization. A number of chiral borylated carbocycles were synthesized in high enantiomeric excess. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

  7. Nanocomposite catalyst with palladium nanoparticles encapsulated in a polymeric acid: A model for tandem environmental catalysis

    KAUST Repository

    Isimjan, Tayirjan T.

    2013-04-01

    The synthesis and characterization of a novel hybrid nanocomposite catalyst comprised of palladium nanoparticles embedded in polystyrene sulfonic acid (PSSH) and supported on metal oxides is reported. The catalysts are intended for application in green catalysis, and they are shown to be effective in the hydrolysisreduction sequence of tandem catalytic reactions required for conversion of 2-phenyl-1,3-dioxolane to toluene or of phenol to cyclohexane. The two distinct components in the catalyst, Pd nanoparticles and acidic PSSH, are capable of catalyzing sequential reactions in one pot under mild conditions. This work has demonstrated a powerful approach toward designing highperformance, multifunctional, scalable, and environmentally friendly nanostructured tandem catalysts. © 2013 American Chemical Society.

  8. Hollow Palladium Nanoparticles Facilitated Biodegradation of an Azo Dye by Electrically Active Biofilms

    KAUST Repository

    Kalathil, Shafeer

    2016-08-04

    Dye wastewater severely threatens the environment due to its hazardous and toxic effects. Although many methods are available to degrade dyes, most of them are far from satisfactory. The proposed research provides a green and sustainable approach to degrade an azo dye, methyl orange, by electrically active biofilms (EABs) in the presence of solid and hollow palladium (Pd) nanoparticles. The EABs acted as the electron generator while nanoparticles functioned as the electron carrier agents to enhance degradation rate of the dye by breaking the kinetic barrier. The hollow Pd nanoparticles showed better performance than the solid Pd nanoparticles on the dye degradation, possibly due to high specific surface area and cage effect. The hollow cavities provided by the nanoparticles acted as the reaction centers for the dye degradation.

  9. Palladium-catalyzed heteroannulation approach to 7-azatryptophan with a Schöllkopf chiral auxiliary

    Energy Technology Data Exchange (ETDEWEB)

    Gee, Moon Bae; Kim, Tae Seung; Yun, Eul Kgun [Dept. of Chemistry, Chungnam National University, Daejeon (Korea, Republic of)

    2015-05-15

    Our previous results on heteroannulation with unprotected 2-amino-3-iodopyridine and internal alkynes showed very low yields of the annulated product. The synthetic limitation could be due to the low nucleophilicity of the nitrogen that exists in the three tautomeric forms of 2-amino-pyridine (Scheme 1) or to the easy formation of a palladium complex with 2-aminopyridine. First, we examined the synthesis of the azaindole precursor, followed by reaction with a Schöllkopf chiral auxiliary. The heteroannulation provided the desired annulated product 5 in 60% yield, along with an uncyclized Sonogawasihra coupling product. After purifying product 5 by column chromatography, it was converted to 7-aza-tryptophan.

  10. Effect of adhesion promoting monomer addition to MMA-TBBO resin on bonding to pure palladium.

    Science.gov (United States)

    Minami, Hiroyuki; Murahara, Sadaaki; Muraguchi, Koichi; Sakoguchi, Kenji; Suzuki, Shiro; Tanaka, Takuo

    2013-01-01

    This study evaluated the effects of combined use of metal primers and modified monomers on the bonding of MMA-TBBO resins to pure palladium (Pd). Bonding surface was polished with 600-grit silicon carbide paper and primed with one of these four metal primers: V-Primer, M. L. Primer, Metaltite, or Alloy Primer. Four monomers, including three modified ones, were added to MMATBBO resin. One was a methyl methacrylate monomer containing no adhesion promoting monomers, while the other two modified monomers contained the functional monomer of either V-Primer or Alloy Primer. Bonded specimens were prepared by incremental build-up of MMA-TBBO resin on primed Pd surfaces. Shear bond strengths were measured after thermal cycling. Bonding to Pd was significantly improved when modified monomer containing the functional monomer of Alloy Primer was used in combination with M. L. Primer or Metaltite applied on the bonding surface.

  11. Synthesis, Characterization, and Biological Activity of Nickel (II and Palladium (II Complex with Pyrrolidine Dithiocarbamate (PDTC

    Directory of Open Access Journals (Sweden)

    Sk Imadul Islam

    2016-01-01

    Full Text Available The synthesis of square planar Ni(II and Pd(II complexes with pyrrolidine dithiocarbamate (PDTC was characterized by elemental, physiochemical, and spectroscopic methods. Two complexes were prepared by the reaction of nickel acetate and palladium acetate with pyrrolidine dithiocarbamate (PDTC in 1 : 2 molar ratio. The bovine serum albumin (BSA interaction with complexes was examined by absorption and fluorescence spectroscopic techniques at pH 7.4. All the spectral data suggest that coordination of the pyrrolidine dithiocarbamate (PDTC takes place through the two sulphur atoms in a symmetrical bidentate fashion. All the synthesized compounds were screened for their antimicrobial activity against some species of pathogenic bacteria (Escherichia coli, Vibrio cholerae, Streptococcus pneumonia, and Bacillus cereus. It has been observed that complexes have higher activity than the free ligand.

  12. Gold and palladium adsorption from leached electronic scrap using ordered mesoporous carbon nanoscaffolds

    Energy Technology Data Exchange (ETDEWEB)

    McDowell, Rocklan; Dutech, Guy

    2014-09-01

    Ordered mesoporous carbon (OMC) nanoscaffolds are engineered agglomerates of carbon nanotubes held together by small carbon nanofibers with uniform pore sizes, high pore volume, and high channel permeability. These materials exhibit very high affinity for the adsorption of gold from aqueous acidic mixtures. The efficiency of gold recovery is comparable to those typically accomplished using biopolymer-based adsorbents. The adsorption efficiency for other precious metals such as palladium and platinum is lower. Studies on the precious metal (Au, Pd) adsorption on OMC materials from actual liquors of leached electronics will be presented. Adsorption properties will be compared for several different sorbents used for the recovery of precious metals. The leach liquor compositions for three different types of electronic scrap materials (personal computer board, cell phone and tv input/output board) will be presented. The sorption efficiencies for Au, Pd, together with a spectrum of competing and non-competing metals, from such leach mixtures will be compared.

  13. Ultrasound agitated phytofabrication of palladium nanoparticles using Andean blackberry leaf and its photocatalytic activity

    Directory of Open Access Journals (Sweden)

    Brajesh Kumar

    2015-09-01

    Full Text Available In this report, ultrasonication and Andean blackberry leaf extract are employed for the fabrication of palladium nanoparticles (PdNPs; and further evaluated its photocatalytic activity against methylene blue (MB. The as-synthesized PdNPs were characterized using UV–visible spectroscopy, transmission electron microscopy (TEM, Dynamic light scattering (DLS and X-ray diffraction (XRD. TEM analysis demonstrated the formation of decahedron shape PdNPs with a diameter of 55–60 nm and XRD confirmed its crystalline nature. It showed photocatalytic decomposition of MB (>72%, k = 0.002164 min−1, 10 mg/L in an aqueous solution under solar light irradiation. From the results obtained it is suggested that ultrasound agitated aqueous leaf extract demonstrates a simple, rapid, inexpensive method and should be utilized in future as green technology for the fabrication of nanoparticles.

  14. Selective extraction of copper, mercury, silver and palladium ionsfrom water using hydrophobic ionic liquids.

    Energy Technology Data Exchange (ETDEWEB)

    Papaiconomou, Nicolas; Lee, Jong-Min; Salminen, Justin; VonStosch, Moritz; Prausnitz, John M.

    2007-06-25

    Extraction of dilute metal ions from water was performed near room temperature with a variety of ionic liquids. Distribution coefficients are reported for fourteen metal ions extracted with ionic liquids containing cations 1-octyl-4-methylpyridinium [4MOPYR]{sup +}, 1-methyl-1-octylpyrrolidinium [MOPYRRO]{sup +} or 1-methyl-1-octylpiperidinium [MOPIP]{sup +}, and anions tetrafluoroborate [BF{sub 4}]{sup +}, trifluoromethyl sulfonate [TfO]{sup +} or nonafluorobutyl sulfonate [NfO]{sup +}. Ionic liquids containing octylpyridinium cations are very good for extracting mercury ions. However, other metal ions were not significantly extracted by any of these ionic liquids. Extractions were also performed with four new task-specific ionic liquids. Such liquids containing a disulfide functional group are efficient and selective for mercury and copper, whereas those containing a nitrile functional group are efficient and selective for silver and palladium.

  15. Enantioselective construction of quaternary N-heterocycles by palladium-catalysed decarboxylative allylic alkylation of lactams

    KAUST Repository

    Behenna, Douglas C.

    2011-12-18

    The enantioselective synthesis of nitrogen-containing heterocycles (N-heterocycles) represents a substantial chemical research effort and resonates across numerous disciplines, including the total synthesis of natural products and medicinal chemistry. In this Article, we describe the highly enantioselective palladium-catalysed decarboxylative allylic alkylation of readily available lactams to form 3,3-disubstituted pyrrolidinones, piperidinones, caprolactams and structurally related lactams. Given the prevalence of quaternary N-heterocycles in biologically active alkaloids and pharmaceutical agents, we envisage that our method will provide a synthetic entry into the de novo asymmetric synthesis of such structures. As an entry for these investigations we demonstrate how the described catalysis affords enantiopure quaternary lactams that intercept synthetic intermediates previously used in the synthesis of the Aspidosperma alkaloids quebrachamine and rhazinilam, but that were previously only available by chiral auxiliary approaches or as racemic mixtures. © 2012 Macmillan Publishers Limited. All rights reserved.

  16. Spatially isolated palladium in porous organic polymers by direct knitting for versatile organic transformations

    KAUST Repository

    Wang, Xinbo

    2017-10-03

    We report here a direct knitting Method for preparation of highly robust, effective while air- and moisture-tolerant, and readily recyclable three-dimensional (3D) porous polymer-Pd network (PPPd) from the widely used Pd(PPh3)4. Electro-beam induced Pd atom crystallization was observed for the first time in organic polymer and revealed the ultrafine dispersion of palladium atoms. Challenging types of Suzuki-Miyaura couplings, reductive coupling of aryl halides and oxidative coupling of arylboronic acid were successively catalyzed by PPPd in aqueous media. Also catalytically selective CH functionalization reactions were achieved with orders of magnitude more efficient than conventional Pd homogeneous catalysts. The strategy developed here provides a practical method for easy-to-make yet highly efficient heterogeneous catalysis.

  17. Palladium catalyst system comprising zwitterion and/or acid-functionalized ionic liquid

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention concerns a catalyst system in particular a catalyst system comprising Palladium (Pd), a zwitterion and/or an acid-functionalized ionic liquid, and one or more phosphine ligands, wherein the Pd catalyst can be provided by a complex precursor, such as Pd(CH3COO)2, PdCI2, Pd(CH3......COCHCOCH3), Pd (CF3COO)2, Pd(PPh3)4 or Pd2(dibenzylideneacetone)3. Such catalyst systems can be used for e.g. alkoxycarbonylation reactions, carboxylation reactions, and/or in a co-polymerization reaction, e.g. in the production of methyl propionate and/or propanoic acid, optionally in processes forming...... methyl methacrylate and/or methacrylic acid. Catalyst systems according to the invention are suitable for reactions forming separable product and catalyst phases and supported ionic liquid phase SILP applications....

  18. Corrosion resistance of cobalt-chromium and palladium-silver alloys used in fixed prosthetic restorations.

    Science.gov (United States)

    Viennot, Stéphane; Dalard, Francis; Lissac, Michèle; Grosgogeat, Brigitte

    2005-02-01

    The corrosion resistance of a cobalt-chromium (Co-Cr) alloy was assessed with a view to determining its potential use in the manufacture of fixed dental prostheses. The electrochemical behaviour of the alloy was compared with that of two palladium (Pd)-based alloys. Measurements of corrosion potential and anodic polarization were performed on the alloys, and the specimen surfaces were examined by using scanning electron microscopy. Although the corrosion potential of the Co-Cr alloy was lower than that of the Pd-based alloys, the corrosion currents and polarization resistance values were similar for all three alloys. All materials showed a very high resistance to corrosion. Given that the beneficial mechanical properties of Co-Cr alloys have already been established, this type of alloy may be a suitable alternative for use in the manufacture of fixed dental prostheses.

  19. Effect of pH on the spontaneous synthesis of palladium nanoparticles on reduced graphene oxide

    Science.gov (United States)

    Zhang, Xiaorui; Ooki, Wataru; Kosaka, Yoshinori R.; Okonogi, Akinori; Marzun, Galina; Wagener, Philipp; Barcikowski, Stephan; Kondo, Takahiro; Nakamura, Junji

    2016-12-01

    Palladium (Pd) nanoparticles were spontaneously deposited on reduced graphene oxide (rGO) without any external reducing agents. The prepared Pd/rGO composites were then characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Spontaneous deposition occurred because of a redox reaction between the Pd precursor and rGO, which involved reduction of bivalent Pd to metallic Pd0 and oxidation of the sp2 carbon of rGO to oxygen-containing functional groups. The amount of Pd deposited on rGO varied with pH, and this was attributed to electrostatic interactions between the Pd precursor and rGO based on the results of zeta potential measurements. The importance of the redox reaction in the spontaneous deposition was demonstrated in the experiment with Zn, Ni, Cu, Ag, Pt, Pd, and Au.

  20. Palladium-Catalyzed Reactions of Arylindium Reagents Prepared Directly from Aryl Iodides and Indium Metal

    Science.gov (United States)

    Papoian, Vardan

    2008-01-01

    Treatment of aryl iodides with indium metal in the presence of lithium chloride leads to the formation of an organoindium reagent capable of participating in cross-coupling reactions under transition-metal catalysis. Combination with aryl halides in the presence of 5 mol% Cl2Pd(dppf) furnishes biaryl compounds in good yields; similarly, reaction with acyl halides or allylic acetates/carbonates in the presence of 5–10 mol % palladium catalyst leads to arylketones and allylic substitution products, respectively, in moderate yields. The reactions are tolerant of the presence of protic solvents, and ~85% of the indium metal employed can be recovered by reduction of the residual indium salts with zinc(0). PMID:18722408

  1. cis-Bis[2-(diphenylphosphinobenzenethiolato-κ2P,S]palladium(II

    Directory of Open Access Journals (Sweden)

    Simón Hernández-Ortega

    2008-09-01

    Full Text Available The title compound, [Pd(C18H14PS2], was synthesized by the reaction of (Ph2PC6H4SH with [PdCl2(NCC6H52] in a 2:1 molar ratio in the presence of a slight excess of NEt3 as base in dichloromethane. The compound crystallizes with the Pd(II atom on a twofold rotation axis. The palladium center has a slightly distorted square-planar environment, with the two P—S chelating ligands adopting a cis configuration. The present structure is a pseudo-polymorph of [Pd(C18H14PS2]·CH2Cl2.

  2. Study of Interaction Platinum Salts (Ii and Palladium (Ii on the Biologically Active Ligand

    Directory of Open Access Journals (Sweden)

    Asmat Nizami Kyzy Azizova

    2014-09-01

    Full Text Available Studied complexing ability of platinum (II and palladium (II with a time of personal gray-oxygen and sulfur-containing ligands donor nitrogens in different taniyah. A combination of functional groups. It is found that the complexation unimportant role nature of the starting metal salts, the pH of the medium, the nature of the solvent and the ratio of reactants. Determine the actual denticity tiodiuksusnoy, tiodipro propionic acid, mercaptoethanol, and bis -- hydroxyethyl sulfide. Discovered that a molecule entering the reaction of cysteamine origin walks splitting S–S communication and the resulting deproto-bined mercamine enter into complexation. In non-aqueous medium splitting S–S communication occurs.

  3. Spectral dependence of circular photocurrent in silver-palladium resistive films

    Science.gov (United States)

    Mikheev, G. M.; Saushin, A. S.; Zonov, R. G.; Styapshin, V. M.

    2014-05-01

    The exposure of silver-palladium (Ag-Pd) resistive films to obliquely incident nanosecond pulsed laser radiation with wavelengths of 1064, 532, 354.7, and 266 nm leads to the appearance of a photo-current dependent on the sign of the circular polarization of incident radiation (circular photocurrent). The photocurrent was determined by measuring pulsed photo-emf in a longitudinal geometry for which the plane of laser-radiation incidence onto the film was parallel to the electrodes. It is established that the response signal changes its sign with that of the angle of incidence, significantly decreases with the laser-radiation frequency, and consists of linear and circular contributions. The ratio of the circular to linear signal components significantly decreases with decreasing radiation wavelength. The obtained results can be used for the creation and development of a device capable of determining the sign of polarization of laser radiation.

  4. Palladium-tin catalysts for the direct synthesis of H₂O₂ with high selectivity.

    Science.gov (United States)

    Freakley, Simon J; He, Qian; Harrhy, Jonathan H; Lu, Li; Crole, David A; Morgan, David J; Ntainjua, Edwin N; Edwards, Jennifer K; Carley, Albert F; Borisevich, Albina Y; Kiely, Christopher J; Hutchings, Graham J

    2016-02-26

    The direct synthesis of hydrogen peroxide (H2O2) from H2 and O2 represents a potentially atom-efficient alternative to the current industrial indirect process. We show that the addition of tin to palladium catalysts coupled with an appropriate heat treatment cycle switches off the sequential hydrogenation and decomposition reactions, enabling selectivities of >95% toward H2O2. This effect arises from a tin oxide surface layer that encapsulates small Pd-rich particles while leaving larger Pd-Sn alloy particles exposed. We show that this effect is a general feature for oxide-supported Pd catalysts containing an appropriate second metal oxide component, and we set out the design principles for producing high-selectivity Pd-based catalysts for direct H2O2 production that do not contain gold. Copyright © 2016, American Association for the Advancement of Science.

  5. Highly efficient hydrogen storage system based on ammonium bicarbonate/formate redox equilibrium over palladium nanocatalysts.

    Science.gov (United States)

    Su, Ji; Yang, Lisha; Lu, Mi; Lin, Hongfei

    2015-03-01

    A highly efficient, reversible hydrogen storage-evolution process has been developed based on the ammonium bicarbonate/formate redox equilibrium over the same carbon-supported palladium nanocatalyst. This heterogeneously catalyzed hydrogen storage system is comparable to the counterpart homogeneous systems and has shown fast reaction kinetics of both the hydrogenation of ammonium bicarbonate and the dehydrogenation of ammonium formate under mild operating conditions. By adjusting temperature and pressure, the extent of hydrogen storage and evolution can be well controlled in the same catalytic system. Moreover, the hydrogen storage system based on aqueous-phase ammonium formate is advantageous owing to its high volumetric energy density. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Activation cross-sections of deuteron induced reactions on natural palladium

    Science.gov (United States)

    Ditrói, F.; Tárkányi, F.; Takács, S.; Hermanne, A.; Ignatyuk, A. V.; Baba, M.

    2012-01-01

    Activation cross-sections for deuteron induced reactions were measured on natural palladium up to 40 MeV with the activation method using a stacked-foil irradiation technique and high resolution gamma-spectrometry. Excitation functions are reported for the reactions producing the radionuclides 111Ag, 110mAg, 106mAg, 105Ag, 111mPd, 109Pd, 101Pd, 100Pd, 105Rh, 102gRh, 101mRh, 100Rh and 99gRh. Comparisons with earlier published data and theoretical results of ALICE-IPPE, EMPIRE and the TALYS codes are presented. Calculated yield curves and activity versus depth distributions are also presented for practical applications such as isotope production or thin layer activation.

  7. Palladium nanoparticles deposited on silanized halloysite nanotubes: synthesis, characterization and enhanced catalytic property.

    Science.gov (United States)

    Zhang, Yi; He, Xi; Ouyang, Jing; Yang, Huaming

    2013-10-15

    Palladium (Pd) nanoparticles were deposited on the surface of halloysite nanotubes (HNTs) modified with γ-aminopropyltriethoxysilane (APTES) to produce Pd/NH2-HNTs nanocomposites. The results indicated that Pd nanoparticles were densely immobilized onto NH2-HNTs with an average diameter of ~ 3 nm. The Pd distribution on the surface of silanized HNTs showed much more uniform, and the Pd nanoparticle size became smaller compared with those directly deposited onto HNTs without silanization. Systematic characterization demonstrated that APTES were chemically bonded onto HNTs, and further confirmed the bond formation between Pd and -NH2 groups, which could ensure the firm deposit of Pd nanoparticles on the surface of silanized HNTs. The as-synthesized Pd/NH2-HNTs exhibited an excellent catalytic activity in the liquid-phase hydrogenation of styrene to ethylbenzene with full conversion within 30 min. The mechanism of the deposit of Pd nanoparticles on silanized HNTs was also investigated.

  8. The Palladium-Catalyzed Aerobic Kinetic Resolution of Secondary Alcohols: Reaction Development, Scope, and Applications

    KAUST Repository

    Ebner, Davidâ C.

    2009-12-07

    The first palladium-catalyzed enantioselective oxidation of secondary alcohols has been developed, utilizing the readily available diamine (-)-sparteine as a chiral ligand and molecular oxygen as the stoichiometric oxidant. Mechanistic insights regarding the role of the base and hydrogen-bond donors have resulted in several improvements to the original system. Namely, addition of cesium carbonate and tert-butyl alcohol greatly enhances reaction rates, promoting rapid resolutions. The use of chloroform as solvent allows the use of ambient air as the terminal oxidant at 23 degrees C, resulting in enhanced catalyst selectivity. These improved reaction conditions have permitted the successful kinetic resolution of benzylic, allylic, and cyclopropyl secondary alcohols to high enantiomeric excess with good-to-excellent selectivity factors. This catalyst system has also been applied to the desymmetrization of meso-diols, providing high yields of enantioenriched hydroxyketones.

  9. Single site electronic spectroscopy of palladium chlorin in n-octane matrixes at 7 K

    Science.gov (United States)

    Singh, Amarnauth; Huang, Wen-Ying; Scheiner, Peter; Johnson, Lawrence W.

    2007-01-01

    The high resolution, single site emission and absorption spectra of palladium chlorin (PdC) in n-octane matrixes at 7 K are reported. The emission and Q and Soret band absorption regions were investigated. The vibrational frequencies of the ground and the lowest energy ππ * excited states were determined from luminescence and excitation spectra, respectively. The emission from PdC was entirely phosphorescence. The emission and Q y region spectra of the complex are similar, having intense, narrow origin bands followed by relatively weak but orderly vibrational structure. The Q x region of this metal chlorin does not have a clear origin and exhibits complex vibrational structure which increases in intensity going to higher energy. In the Soret region of PdC there is only a single intense, broad band.

  10. Palladium-catalyzed cross-coupling reactions of potassium alkenyltrifluoroborates with organic halides in aqueous media.

    Science.gov (United States)

    Alacid, Emilio; Nájera, Carmen

    2009-03-20

    Potassium vinyl and alkenyltrifluoroborates are cross-coupled with aryl and heteroaryl bromides using 1 mol % Pd loading of 4-hydroxyacetophenone oxime derived palladacycle or Pd(OAc)2 as precatalysts, K2CO3 as base, and TBAB as additive and water reflux under conventional or microwave heating to afford styrenes, stilbenoids, and alkenylbenzenes. These borates can be cross-coupled diastereoselectively with allyl and benzyl chlorides using KOH as base in acetone-water (3:2) at 50 degrees C and 0.1 mol % Pd loading, giving the corresponding 1,4-dienes and allylarenes, respectively. These simple phosphine-free reaction conditions allow the palladium recycling from the aqueous phase during up to five runs by extractive separation of the products, which contain 58-105 ppm of Pd.

  11. Palladium behavior in the presence of irradiated diluent in the PUREX process

    Energy Technology Data Exchange (ETDEWEB)

    Sio, S. de; Vigier, N. [AREVA NC/DOR/RDP, 1 place Jean Millier, 92084 Paris La Defense (France); Klur, I. [AREVA NC/DT/EP/P, La Hague (France); Tison, E. [AREVA NC/DT/EP/EL, La Hague (France); Bouyer, C.; Eysseric, C. [CEA, Centre de Marcoule, /DEN/DRCP, BP 17171, 30207 Bagnols-sur-Ceze Cedex (France); Lebeau, D.; Goutelard, F. [CEA, Centre de Saclay, /DEN/DPC, 91191 Gif-sur-Yvette Cedex (France); Sejourne, L. [CEA, Centre de Saclay, /DEN/DMN, 91191 Gif-sur-Yvette (France)

    2016-07-01

    AREVA La Hague plants UP3 and UP2-800 started operations to reprocess spent nuclear fuel in 1990 and 1994 respectively. Aging equipment in these plants is a cause for concern as it could lead to process dysfunctions or production rate decrease. A few years ago, several columns had to be replaced in UP3-T4 plutonium purification facility because of clogging. Analyses revealed that TPH degradation products could be responsible for precipitating palladium compounds. 1 M NaOH solutions proved to be efficient to dissolve most of the precipitate. Therefore, several columns in both UP3 and UP2-800 are from now on washed periodically with 1 M NaOH solutions to avoid further clogging and to dissolve current precipitates. (authors)

  12. Structural incorporation of As5+ into hematite.

    Science.gov (United States)

    Bolanz, Ralph M; Wierzbicka-Wieczorek, Mária; Čaplovičová, Mária; Uhlík, Peter; Göttlicher, Jörg; Steininger, Ralph; Majzlan, Juraj

    2013-08-20

    Hematite (α-Fe2O3) is one of the most common iron oxides and a sink for the toxic metalloid arsenic. Arsenic can be immobilized by adsorption to the hematite surface; however, the incorporation of As in hematite was never seriously considered. In our study we present evidence that, besides adsorption, the incorporation of As into the hematite crystals can be of great relevance for As immobilization. With the coupling of nanoresolution techniques and X-ray absorption spectroscopy the presence of As (up to 1.9 wt %) within the hematite crystals could be demonstrated. The incorporated As(5+) displays a short-range order similar to angelellite-like clusters, epitaxially intergrown with hematite. Angelellite (Fe4As2O11), a triclinic iron arsenate with structural relations to hematite, can epitaxially intergrow along the (210) plane with the (0001) plane of hematite. This structural composite of hematite and angelellite-like clusters represents a new immobilization mechanism and potentially long-lasting storage facility for As(5+) by iron oxides.

  13. Atomic-structural synergy for catalytic CO oxidation over palladium-nickel nanoalloys.

    Science.gov (United States)

    Shan, Shiyao; Petkov, Valeri; Yang, Lefu; Luo, Jin; Joseph, Pharrah; Mayzel, Dina; Prasai, Binay; Wang, Lingyan; Engelhard, Mark; Zhong, Chuan-Jian

    2014-05-14

    Alloying palladium (Pd) with other transition metals at the nanoscale has become an important pathway for preparation of low-cost, highly active and stable catalysts. However, the lack of understanding of how the alloying phase state, chemical composition and atomic-scale structure of the alloys at the nanoscale influence their catalytic activity impedes the rational design of Pd-nanoalloy catalysts. This work addresses this challenge by a novel approach to investigating the catalytic oxidation of carbon monoxide (CO) over palladium-nickel (PdNi) nanoalloys with well-defined bimetallic composition, which reveals a remarkable maximal catalytic activity at Pd:Ni ratio of ~50:50. Key to understanding the structural-catalytic synergy is the use of high-energy synchrotron X-ray diffraction coupled to atomic pair distribution function (HE-XRD/PDF) analysis to probe the atomic structure of PdNi nanoalloys under controlled thermochemical treatments and CO reaction conditions. Three-dimensional (3D) models of the atomic structure of the nanoalloy particles were generated by reverse Monte Carlo simulations (RMC) guided by the experimental HE-XRD/PDF data. Structural details of the PdNi nanoalloys were extracted from the respective 3D models and compared with the measured catalytic properties. The comparison revealed a strong correlation between the phase state, chemical composition and atomic-scale structure of PdNi nanoalloys and their catalytic activity for CO oxidation. This correlation is further substantiated by analyzing the first atomic neighbor distances and coordination numbers inside the nanoalloy particles and at their surfaces. These findings have provided new insights into the structural synergy of nanoalloy catalysts by controlling the phase state, composition and atomic structure, complementing findings of traditional density functional theory studies.

  14. EFFECT OF INCORPORATING EXPANDED POLYSTYRENE ...

    African Journals Online (AJOL)

    2012-11-03

    Nov 3, 2012 ... Abstract. Incorporating expanded polystyrene granules in concrete matrix can produce lightweight polystyrene aggregate concrete of various densities. Workability which is an important property of concrete, affects the rate of placement and the degree of compaction of concrete. Inadequate compaction.

  15. Incorporating Argumentation through Forensic Science

    Science.gov (United States)

    Wheeler, Lindsay B.; Maeng, Jennifer L.; Smetana, Lara K.

    2014-01-01

    This article outlines how to incorporate argumentation into a forensic science unit using a mock trial. Practical details of the mock trial include: (1) a method of scaffolding students' development of their argument for the trial, (2) a clearly outlined set of expectations for students during the planning and implementation of the mock…

  16. SYNTHESIS OF THE FULLY PROTECTED PHOSPHORAMIDITE OF THE BENZENE-DNA ADDUCT, N2- (4-HYDROXYPHENYL)-2'-DEOXYGUANOSINE AND INCORPORATION OF THE LATER INTO DNA OLIGOMERS

    Energy Technology Data Exchange (ETDEWEB)

    Chenna, Ahmed; Gupta, Ramesh C.; Bonala, Radha R.; Johnson, Francis; Huang, Bo

    2008-06-09

    N2-(4-Hydroxyphenyl)-2'-deoxyguanosine-5'-O-DMT-3'-phosphoramidite has been synthesized and used to incorporate the N2-(4-hydroxyphenyl)-2'-dG (N2-4-HOPh-dG) into DNA, using solid-state synthesis technology. The key step to obtaining the xenonucleoside is a palladium (Xantphos-chelated) catalyzed N2-arylation (Buchwald-Hartwig reaction) of a fully protected 2'-deoxyguanosine derivative by 4-isobutyryloxybromobenzene. The reaction proceeded in good yield and the adduct was converted to the required 5'-O-DMT-3'-O-phosphoramidite by standard methods. The latter was used to synthesize oligodeoxynucleotides in which the N2-4-HOPh-dG adduct was incorporated site-specifically. The oligomers were purified by reverse-phase HPLC. Enzymatic hydrolysis and HPLC analysis confirmed the presence of this adduct in the oligomers.

  17. An algorithm for segmenting range imagery

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, R.S.

    1997-03-01

    This report describes the technical accomplishments of the FY96 Cross Cutting and Advanced Technology (CC&AT) project at Los Alamos National Laboratory. The project focused on developing algorithms for segmenting range images. The image segmentation algorithm developed during the project is described here. In addition to segmenting range images, the algorithm can fuse multiple range images thereby providing true 3D scene models. The algorithm has been incorporated into the Rapid World Modelling System at Sandia National Laboratory.

  18. Effective and selective recovery of gold and palladium ions from metal wastewater using a sulfothermophilic red alga, Galdieria sulphuraria.

    Science.gov (United States)

    Ju, Xiaohui; Igarashi, Kensuke; Miyashita, Shin-Ichi; Mitsuhashi, Hiroaki; Inagaki, Kazumi; Fujii, Shin-Ichiro; Sawada, Hitomi; Kuwabara, Tomohiko; Minoda, Ayumi

    2016-07-01

    The demand for precious metals has increased in recent years. However, low concentrations of precious metals dissolved in wastewater are yet to be recovered because of high operation costs and technical problems. The unicellular red alga, Galdieria sulphuraria, efficiently absorbs precious metals through biosorption. In this study, over 90% of gold and palladium could be selectively recovered from aqua regia-based metal wastewater by using G. sulphuraria. These metals were eluted from the cells into ammonium solutions containing 0.2M ammonium salts without other contaminating metals. The use of G. sulphuraria is an eco-friendly and cost-effective way of recovering low concentrations of gold and palladium discarded in metal wastewater. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. The Influence of Technological PVD Process Parameters on the Topography, Crystal and Molecular Structure of Nanocomposite Films Containing Palladium Nanograins

    Directory of Open Access Journals (Sweden)

    Rymarczyk Joanna

    2014-09-01

    Full Text Available The paper describes the preparation and characteristics of films composed of Pd nanograins placed in carbonaceous matrix. Films were obtained in PVD (Physical Vapor Deposition process from two sources containing: the first one - fullerene powder and the second one - palladium acetate. The topographical, morphological and structural changes due to different parameters of PVD process were studied with the use of Atomic Force Microscopy and Scanning Electron Microscopy, whereas the structure was studied with the application of the Transmission Electron Microscopy and Fourier Transform Infrared Spectroscopy methods. It was shown that topographical changes are connected with the decomposition ratio of Pd acetate as well as the form of carbonaceous matrix formed due to this decomposition. Palladium nanograins found in all films exhibit the fcc structure type and their diameter changes from 2 nm to 40 nm depending on the PVD process parameters.

  20. Fundamental Mechanistic Investigations of Silane and Chlorocarbon Addition to Low Valent Palladium Species and their Application to Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Fink, Mark J.

    2009-01-27

    The collaboration between Mark Fink (Tulane University) and R. Morris Bullock (Brookhaven National Laboratory, currently at PNL) is an effort to understand some of the fundamental processes involved in catalytic bond activations with low coordinate palladium species. The project involves the photochemical generation of reactive low-valent palladium species as transients using nanosecond laser flash photolysis and the subsequent investigation of their reactions with chloroarenes and hydrosilanes. In the case of Si-H activation of hydrosilanes, relatively long-lived sigma complexes are implicated. These complexes may be important models for C-H activation in hydrocarbons. The information obtained from these studies will help in the understanding of fundamental processes involved in a number of important catalytic reactions in the petrochemical and environmental areas.

  1. Improving carbon tolerance of Ni-YSZ catalytic porous membrane by palladium addition for low temperature steam methane reforming

    Science.gov (United States)

    Lee, Sang Moon; Won, Jong Min; Kim, Geo Jong; Lee, Seung Hyun; Kim, Sung Su; Hong, Sung Chang

    2017-10-01

    Palladium was added on the Ni-YSZ catalytic porous membrane by wet impregnation and electroless plating methods. Its surface morphology characteristics and carbon deposition properties for the low temperature steam methane reforming were investigated. The addition of palladium could obviously be enhanced the catalytic activity as well as carbon tolerance of the Ni-YSZ porous membrane. The porous membranes were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR), CH4 temperature-programmed reduction (CH4-TPR), and O2 temperature-programmed oxidation (O2-TPO). It was found that the Pd-Ni-YSZ catalytic porous membrane showed the superior stability as well as the deposition of carbon on the surface during carbon dissociation adsorption at 650 °C was also suppressed.

  2. Palladium(II) complexes bearing di-(2-picolyl)amine functionalized chrysin fragments. An experimental and theoretical study

    Science.gov (United States)

    González-Montiel, Simplicio; Valdez-Calderón, Alejandro; Vásquez-Pérez, J. Manuel; Torres-Valencia, J. Martín; Martínez-Otero, Diego; López, Jorge A.; Cruz-Borbolla, Julián

    2017-10-01

    A new series of chrysin derivatives containing the di-(2-picolyl)amine (2a-d) moiety have been designed, synthesized, and treated with PdCl2·2CH3CN allowing the preparation of new cationic Palladium(II) complexes (3a-d). Solution-phase studies by 1H NMR spectroscopy of 3a-d revealed that the protons of the methylene groups of the di(2-picolyl)amine fragment are diasterotopic. GIAO/DFT studies were performed to predict the molecular structures of 3a-d by comparing the experimental and theoretical 1H-NMR chemical shifts. The molecular structure of 3c was determined by X-ray crystallographic analysis revealing that di-(2-picolyl)amine fragment is coordinated to the palladium center in a κ3-N,N,N-tridentate fashion in an overall square-planar geometry completed with a chloride atom.

  3. Monodisperse gold-palladium alloy nanoparticles and their composition-controlled catalysis in formic acid dehydrogenation under mild conditions

    Science.gov (United States)

    Metin, Önder; Sun, Xiaolian; Sun, Shouheng

    2013-01-01

    Monodisperse 4 nm AuPd alloy nanoparticles with controlled composition were synthesized by co-reduction of hydrogen tetrachloroaurate(iii) hydrate and palladium(ii) acetylacetonate with a borane-morpholine complex in oleylamine. These NPs showed high activity (TOF = 230 h-1) and stability in catalyzing formic acid dehydrogenation and hydrogen production in water at 50 °C without any additives.Monodisperse 4 nm AuPd alloy nanoparticles with controlled composition were synthesized by co-reduction of hydrogen tetrachloroaurate(iii) hydrate and palladium(ii) acetylacetonate with a borane-morpholine complex in oleylamine. These NPs showed high activity (TOF = 230 h-1) and stability in catalyzing formic acid dehydrogenation and hydrogen production in water at 50 °C without any additives. Electronic supplementary information (ESI) available: Experimental procedures (NP synthesis, characterization and catalytic FA dehydrogenation) and figures (Fig. S1-S5). See DOI: 10.1039/c2nr33637e

  4. Investigating the nature of palladium chain-walking in the enantioselective redox-relay Heck reaction of alkenyl alcohols.

    Science.gov (United States)

    Hilton, Margaret J; Xu, Li-Ping; Norrby, Per-Ola; Wu, Yun-Dong; Wiest, Olaf; Sigman, Matthew S

    2014-12-19

    The mechanism of the redox-relay Heck reaction was investigated using deuterium-labeled substrates. Results support a pathway through a low energy palladium-alkyl intermediate that immediately precedes product formation, ruling out a tautomerization mechanism. DFT calculations of the relevant transition structures at the M06/LAN2DZ+f/6-31+G* level of theory show that the former pathway is favored by 5.8 kcal/mol. Palladium chain-walking toward the alcohol, following successive β-hydride eliminations and migratory insertions, is also supported in this study. The stereochemistry of deuterium labels is determined, lending support that the catalyst remains bound to the substrate during the relay process and that both cis- and trans-alkenes form from β-hydride elimination.

  5. Total arsenic in urine: palladium-persulfate vs nickel as a matrix modifier for graphite furnace atomic absorption spectrophotometry.

    Science.gov (United States)

    Nixon, D E; Mussmann, G V; Eckdahl, S J; Moyer, T P

    1991-09-01

    We evaluated the effectiveness of nickel and palladium with or without added potassium persulfate as matrix modifiers for the determination of total arsenic in urine. Complete recovery of pure aqueous solutions of As(III), As(V), cacodylic acid (DMA), monomethylarsinic acid (MMA), and o-arsanilic acid was attained by using both nickel and palladium modifiers. Combined arsenobetaine and arsenocholine (so-called fish arsenic), extracted from a certified control material of dogfish muscle (DORM-1), were completely recovered with Pd-S2O8 matrix modification, but not with nickel. Excellent agreement with target values for arsenic in urines from the Centre de Toxicologie du Quebec, supplied by the Interlaboratory Comparison Program, was attained irrespective of the arsenic source when we used Pd-S2O8 as the matrix modifier.

  6. Copper(II) and palladium(II) complexes with tridentate NSO donor Schiff base ligand: Synthesis, characterization and structures

    Science.gov (United States)

    Kumar, Sujit Baran; Solanki, Ankita; Kundu, Suman

    2017-09-01

    Mononuclear copper(II) complex [CuL2] and palladium(II) complexes [Pd(X)L] where X = benzoate(bz) or salicylate(sal) and HL = 2-(methylthio)phenylimino)methyl)phenol, a Schiff base ligand with NSO coordination sites have been synthesized and characterized by microanalyses, IR, UV-Visible spectra, conductivity measurement and magnetic studies. Crystal structures of all the complexes have been solved by single crystal X-ray diffraction studies and showed that there are two molecules in a unit cell in the [CuL2] complex - one molecule has square planar geometry whereas second molecule has distorted square pyramidal geometry and palladium(II) complexes have distorted square planar geometry.

  7. Frontal and band displacement chromatography of the hydrogen isotopes on palladium; Chromatographies frontale et de deplacement de bande des isotopes de l'hydrogene sur palladium

    Energy Technology Data Exchange (ETDEWEB)

    Botter, F.; Menes, J.; Tistchenko, S.; Dirian, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    As a result of hydrogen isotope separations which we have carried out on supports containing palladium, we believe that we can now make a double contribution, theoretical and experimental, to the work which has already been published in this field. From the fundamental point of view we have developed and studied the validity of a simple model, in our particular case of a separation coefficient {alpha} which is very different to unity. This model, which is of a counter-current isotopic exchange, neglects the longitudinal diffusion in the gas phase and the lateral diffusion in the adsorbed phase and only takes into account the surface resistance to exchange between the phases. It is therefore possible to estimate the efficiency of a chromatography column in terms of the height equivalent of a theoretical plate (HETP). The slight differences observed between the actual chromatograms and the simple model justify both the research undertaken into a more complex model taking into account the diffusion, and the adoption of a simple model for comparing the efficiency of several columns. We describe also a new and simple graphical method for deducing the number of theoretical plates of a column in chromatograms of the frontal and band displacement types. Experimentally we give in particular the criteria for the validity of the model used, the law as a function of the {sup {alpha}}H{sub 2}-HD temperature, the study of the HETP as a function of the various parameters on several palladium containing supports, and the possibilities of an application to preparative chromatography. (authors) [French] Grace aux separations des isotopes de l'hydrogene que nous avons realisees sur masses palladiees, nous pensons apporter aux etudes precedemment publiees dans ce domaine, une double contribution, theorique et experimentale. Du point de vue fondamental, on a developpe et etudie la validite d'un modele simple, dans notre cas particulier d'un coefficient de separation

  8. Synthesis of palladium(0) and -(II) complexes with chelating bis(N-heterocyclic carbene) ligands and their application in semihydrogenation

    OpenAIRE

    Sluijter, S.N.; Warsink, S.; Lutz, M.; Elsevier, C.J.

    2013-01-01

    A transmetallation route, using silver(I) precursors, to several zero-and di-valent palladium complexes with chelating bis(N-heterocyclic carbene) ligands bearing various N-substituents has been established. The resulting complexes have been characterized by NMR and mass spectroscopy. In addition, the structure of a representative compound, [Pd-0(bis-(Mes)NHC)(eta(2)-ma)] (3a), was confirmed by X-ray crystal structure determination. In contrast to the transfer semihydrogenation, in which only...

  9. Sequential rhodium/palladium catalysis: enantioselective formation of dihydroquinolinones in the presence of achiral and chiral ligands.

    Science.gov (United States)

    Zhang, Lei; Qureshi, Zafar; Sonaglia, Lorenzo; Lautens, Mark

    2014-12-08

    Compatible combinations of achiral and chiral ligands can be used in rhodium/palladium catalysis to achieve highly enantioselective domino reactions. The difference in rates of catalysis and minimal effects of ligand interference confer control in the domino sequence. The "all-in-one" 1,4-conjugate arylation and C-N cross-coupling through sequential Rh/Pd catalysis provides access to enantioenriched dihydroquinolinone building blocks. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Palladium-Catalyzed Heck Coupling Reaction of Aryl Bromides in Aqueous Media Using Tetrahydropyrimidinium Salts as Carbene Ligands

    Directory of Open Access Journals (Sweden)

    İsmail Özdemir

    2010-01-01

    Full Text Available An efficient and stereoselective catalytic system for the Heck cross coupling reaction using novel 1,3-dialkyl-3,4,5,6-tetrahydropyrimidinium salts (1, LHX and Pd(OAc2 loading has been reported. The palladium complexes derived from the salts 1a-f prepared in situ exhibit good catalytic activity in the Heck coupling reaction of aryl bromides under mild conditions.

  11. N-Heterocyclic carbene–palladium(II-1-methylimidazole complex catalyzed Mizoroki–Heck reaction of aryl chlorides with styrenes

    Directory of Open Access Journals (Sweden)

    Ting-Ting Gao

    2012-11-01

    Full Text Available A well-defined N-heterocyclic carbene–palladium(II-1-methylimidazole [NHC-Pd(II-Im] complex 1 was found to be an effective catalyst for the Mizoroki–Heck reaction of a variety of aryl chlorides with styrenes. Both activated and deactivated aryl chlorides work well to give the corresponding coupling products in good to excellent yields by using tetrabutylammonium bromide (TBAB as the ionic liquid.

  12. Evidence for the production of d-d fusion neutrons during electrolytic infusion of deuterons into a palladium cylinder

    Energy Technology Data Exchange (ETDEWEB)

    Ohms, D.; Paffrath, E.; Rahner, D.; Schwierz, R.; Selliger, D.; Stiekl, P.; Wiesener, K.; Wustner, P.; Bittner, M.; Ludwig, G.; Meister, A.; Muller, J. (Dresden Univ. of Technology, Physics and Chemistry Dept., Mommsenstrasse 13, O-8027 Dresden (DE))

    1991-07-01

    A lengthy experiment for the observation of deuteron-deuteron (d-d) fusion neutrons emanating from a massive palladium cylinder is described. The experimental results are discussed in the framework of a plasmalike model for fusion in condensed matter, resulting in fusion rates of {lambda}{sup pl}{sub d{minus}d} = (1.19 {plus minus} 0.15) {times} 10{sup {minus}44} s{sup {minus}1}.

  13. Solubility and spectroscopic studies of the interaction of palladium with simple carboxylic acids and fulvic acid at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wood, S.A. (Univ. of Idaho, Moscow, ID (United States)); Tait, C.D.; Janecky, D.R. (Los Alamos National Laboratory, NM (United States)); Vlassopoulos, D. (California Institute of Technology, Pasadena, CA (United States))

    1994-01-01

    The interaction of Pd with some O-donor organic acid anions has been investigated using solubility measurements and a variety of spectroscopic techniques (UV-visible, Raman, FTIR, [sup 13]C NMR). Some of the ligands investigated (acetate, oxalate, and fulvic acid) occur naturally in relatively high concentrations, whereas others (phthalate and salicylate) serve as models of potential binding sites on humic and fulvic acids. Solubility measurements show that the presence of acetate, phthalate, salicylate, and fulvic acid (oxalate was not studied via solubility methods) can increase the mobility of Pd over various pH ranges, depending on the organic ligand. In the case of acetate, UV-visible and Raman spectroscopy provide strong evidence for the formation of electrostatically bound, possibly outer-sphere palladium acetate complexes. Oxalate was confirmed by UV-visible and FTIR spectroscopy to compete favorably with chloride (0.56 M NaCl) for Pd even at oxalate concentrations as low as 1 mM at pH = 6-7. Available data from the literature suggest that oxalate may have an influence on Pd mobility at free oxalate concentrations as low as 10[sup [minus]8]=10[sup [minus]9] M. UV-visible spectroscopy provides evidence of an initially rapid, followed by a slower, reaction between PdCl[sup 2-][sub 4] and o-phthalate ion. These findings lend support to the idea that similar bindings sites on fulvic acid may be capable of complexing and solubilizing Pd in the natural environment. Although thermodynamic data are required to fully quantify the extent, it is concluded that simple carboxylic acid anions and/or fulvic and humic acids should be capable of significantly enhancing Pd transport in the surficial environment by forming truly dissolved complexes. On the other hand, flocculation of fulvic/humic acids, owing to changing ionic strengths or pH, or adsorption of these acids onto mineral surfaces, may also provide effective means of immobilizing Pd.

  14. A cost-effective and practical polybenzanthrone-based fluorescent sensor for efficient determination of palladium (II) ion and its application in agricultural crops and environment.

    Science.gov (United States)

    Zhang, Ge; Wen, Yangping; Guo, Chaoqun; Xu, Jingkun; Lu, Baoyang; Duan, Xuemin; He, Haohua; Yang, Jun

    2013-12-17

    A highly selective and sensitive fluorescent chemosensor suitable for practical measurement of palladium ion (Pd(2+)) in agricultural crops and environment samples has been successfully fabricated using polybenzanthrone (PBA). PBA was facilely electrosynthesized in the mixed electrolyte of acetonitrile and boron trifluoride diethyl etherate. The fluorescence intensity of PBA showed a linear response to Pd(2+) in the concentration range of 5 nM-0.12 mM with a detection limit of 0.277 nM and quantification limit of 0.925 nM. Different compounds existing in agricultural crops and environment such as common metal ions, anions, natural amino acids, carbohydrates, and organic acids were used to examine the selectivity of the as-fabricated sensor, and no obvious fluorescence change could be observed in these interferents and their mixtures. A possible mechanism was proposed that the coordination of PBA and Pd(2+) enhance the aggregation of polymer chains, which led to a significant quenching of PBA emission, and this was further confirmed by absorption spectra monitoring and transmission electron microscopy. The excellent performance of the proposed sensor and satisfactory results of the Pd(2+) determination in practical samples suggested that the PBA-based fluorescent sensor for the determination of Pd(2+) will be a good candidate for application in agriculture and environment. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Green Synthesis of Palladium/Titanium Dioxide Nanoparticles and Their Application for the Reduction of Methyl Orange, Congo Red and Rhodamine B in Aqueous Medium.

    Science.gov (United States)

    Maham, Mehdi; Nasrollahzadeh, Mahmoud; Bagherzadeh, Mojtaba; Akbari, Reza

    2017-10-23

    Palladium nanoparticles (Pd NPs) supported on the TiO2 NPs were prepared via a green alternative process using Euphorbia thymifolia L. leaf extract as a reducing and stabilizing agent. This extract has both the reducing compounds, as phenolic acids, and stabilizing agents, as flavonols that responsible for the bioreduction of Pd2+ and stabilization of Pd NPs. The Pd/TiO2 NPs were characterized by field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM) and X-ray diffraction analysis (XRD). The Pd/TiO2 NPs exhibited high activity towards the reduction of Methyl Orange (MO), Congo red (CR) and Rhodamine B (RhB) in the presence of NaBH4 in aqueous medium. FESEM imaging showed the formation of NPs in the size range of 19-29 nm. The catalytic reduction reactions were monitored by employing UV-visible spectroscopy. Furthermore, the catalyst can be recovered and recycled several times without significant loss of activity. To the best of the author's knowledge, this study explains the first report to synthesis of Pd/TiO2 NPs using Euphorbia thymifolia L. leaf extract. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  16. Rapid determination of rivaroxaban in human urine and serum using colloidal palladium surface-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Cheng, Yu-Han; Chen, Wen-Chi; Chang, Sarah Y

    2015-11-15

    Rivaroxaban is a new anticoagulant drug that has recently been introduced for clinical applications. To ensure optimum efficacy while minimizing the risk of toxicity and other adverse effects, a simple and sensitive analytical procedure for monitoring the concentration of rivaroxaban in biological fluids is required. Rivaroxaban was extracted from aqueous solutions by dispersive liquid-liquid microextraction (DLLME). Detection of rivaroxaban was achieved through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using colloidal palladium as the SALDI matrix. The calibration curve for rivaroxaban in aqueous solutions was linear over the concentration range from 5 to 500 nM. The limit of detection (LOD) for rivaroxaban at a signal-to-noise ratio of 3 was 2 nM. With a sample-to-extract volume ratio of 200, the enrichment factors were calculated to be 141. This method was successfully applied for the determination of rivaroxaban in human urine and serum samples. The LODs for rivaroxaban in urine and serum were calculated to be 6 nM and 60 nM, respectively. The analysis speed, together with the ease of operation and high sensitivity, allows SALDI-MS method to be particularly suitable for the high-throughput screening of rivaroxaban levels in human urine and serum samples. Copyright © 2015 John Wiley & Sons, Ltd.

  17. Improved recovery of trace amounts of gold (III), palladium (II) and platinum (IV) from large amounts of associated base metals using anion-exchange resins.

    Science.gov (United States)

    Matsubara, I; Takeda, Y; Ishida, K

    2000-02-01

    The adsorption and desorption behaviors of gold (III), palladium (II) and platinum (IV) were surveyed in column chromatographic systems consisting of one of the conventional anion-exchange resins of large ion-exchange capacity and dilute thiourea solutions. The noble metals were strongly adsorbed on the anion-exchange resins from dilute hydrochloric acid, while most base metals did not show any marked adsorbability. These facts made it possible to separate the noble metals from a large quantity of base metals such as Ag (I), Al (III), Co (II), Cu (II), Fe (III), Mn (II), Ni (II), Pb (II), and Zn (II). Although it used to be very difficult to desorb the noble metals from the resins used, the difficulty was easily overcome by use of dilute thiourea solutions as an eluant. In the present study, as little as 1.00 microg of the respective noble metals was quantitatively separated and recovered from as much as ca. 10 mg of a number of metals on a small column by elution with a small amount of dilute thiourea solution. The present systems should be applicable to the separation, concentration and recovery of traces of the noble metals from a number of base metals coexisting in a more extended range of amounts and ratios.

  18. Facile synthesis of palladium nanoparticles supported on multi-walled carbon nanotube for efficient hydrogenation of biomass-derived levulinic acid

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Kai, E-mail: kyan@lakeheadu.ca; Lafleur, Todd [Lakehead University, Department of Chemistry (Canada); Liao, Jiayou [Tianjin University, School of Chemical Engineering and Technology (China)

    2013-09-15

    Different loading of palladium (Pd) nanoparticles were successfully fabricated on multi-walled carbon nanotubes using Pd acetylacetonate as the precursor via a simple liquid impregnation method. The crystal phase, morphology, textural structure and the chemical state of the resulting Pd nanoparticles (Pd/CNT) catalysts were studied and the characterization results indicated that the uniform dispersion of small Pd nanoparticles with the size range of 1.0-4.5 nm was achieved. The synthesized Pd/CNT catalysts exhibited efficient performance for the catalytic hydrogenation of biomass-derived levulinic acid into biofuel {gamma}-valerolactone. In comparison with the commercial 5 wt% Pd/C and the 5 wt% Pd/CNT catalyst prepared by Pd nitrate precursor, much higher activities were achieved, whereas the biofuel {gamma}-valerolactone was highly produced with 56.3 % yield at 57.6 % conversion of levulinic acid on the 5 wt% Pd/CNT catalyst under mild conditions. The catalyst developed in this work may be a good candidate for the wide applications in the hydrogenation.

  19. 3D Nanostructured Palladium-Functionalized Graphene-Aerogel-Supported Fe3O4 for Enhanced Ru(bpy)32+-Based Electrochemiluminescent Immunosensing of Prostate Specific Antigen.

    Science.gov (United States)

    Yang, Lei; Li, Yueyuan; Zhang, Yong; Fan, Dawei; Pang, Xuehui; Wei, Qin; Du, Bin

    2017-10-11

    We developed a novel Ru(bpy)32+-based electrochemiluminescence (ECL) immunosensor utilizing palladium nanoparticle (Pd NP)-functionalized graphene-aerogel-supported Fe3O4 (FGA-Pd) for real-sample analysis of prostate specific antigen (PSA). 3D nanostructured FGA-Pd, as a novel ECL carrier, was prepared by in situ reduction. Large amounts of Ru(bpy)32+ could combine with FGA-Pd via electrostatic interaction to establish a brand-new ECL emitter (Ru@FGA-Pd) for improving ECL efficiency. The obtained Ru@FGA-Pd composite was utilized to label the secondary antibody, which generated strong ECL signals with tripropylamine (TPrA) as a coreactant. Furthermore, we demonstrated that the participation of Pd NPs endowed FGA with favorable electrocatalytic ability in the luminescence process to produce more excited state [Ru(bpy)32+]* for realizing desirable signal amplification. In addition, the primary antibody was captured by gold nanoparticle (Au NP)-functionalized Fe2O3 nanodendrites (Au-FONDs), which possessed good electrical conductivity and favorable biocompatibility. Under optimum conditions, the fabricated sandwich-type ECL immunosensor showed a sensitive response to PSA with a low detection limit of 0.056 pg/mL (S/N = 3) and a calibration range of 0.0001-50 ng/mL. Featuring favorable selectivity, stability, and repeatability, the proposed immunosensor is expected to blaze a novel trail for the real sample detection of PSA and other biomarkers.

  20. Room temperature trapping of stibine and bismuthine onto quartz substrates coated with nanostructured palladium for total reflection X-ray fluorescence analysis

    Science.gov (United States)

    Romero, Vanesa; Costas-Mora, Isabel; Lavilla, Isela; Bendicho, Carlos

    2015-05-01

    In this work, a novel method for determining Sb and Bi based on the trapping of their covalent hydrides onto quartz reflectors coated with immobilized palladium nanoparticles (Pd NPs) followed by total reflection X-ray fluorescence (TXRF) analysis is proposed. Pd NPs were synthesized by chemical reduction of the metal precursor using a mixture of water:ethanol as mild reducing agent. Silanization using 3-mercaptopropyltrimethoxysilane (MPTMS) was performed for the immobilization of Pd NPs onto the quartz substrates. Volatile hydrides (stibine and bismuthine) generated by means of a continuous flow system were flushed onto the immobilized Pd NPs and retained by catalytic decomposition. As a result of the high catalytic activity of the nanostructured film, trapping can be performed at ambient temperature with good efficiency. Limits of detection (LODs) were 2.3 and 0.70 μg L- 1 for Sb and Bi, respectively. Enrichment factors of 534 and 192 were obtained for Sb and Bi, respectively. The new method was applied for the analysis of several matrices (milk, soil, sediment, cutaneous powder). Recoveries were in the range of 98.4-101% for both elements with a relative standard deviation of 2.5% (N = 5).