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Sample records for ni-based organometallic compounds

  1. Organometallic compounds: an opportunity for chemical biology?

    PubMed

    Patra, Malay; Gasser, Gilles

    2012-06-18

    Organometallic compounds are renowned for their remarkable applications in the field of catalysis, but much less is known about their potential in chemical biology. Indeed, such compounds have long been considered to be either unstable under physiological conditions or cytotoxic. As a consequence, little attention has been paid to their possible utilisation for biological purposes. Because of their outstanding physicochemical properties, which include chemical stability, structural diversity and unique photo- and electrochemical properties, however, organometallic compounds have the ability to play a leading role in the field of chemical biology. Indeed, remarkable examples of the use of such compounds-notably as enzyme inhibitors and as luminescent agents-have recently been reported. Here we summarise recent advances in the use of organometallic compounds for chemical biology purposes, an area that we define as "organometallic chemical biology". We also demonstrate that these recent discoveries are only a beginning and that many other organometallic complexes are likely to be found useful in this field of research in the near future.

  2. Synthesis of organometallic compounds: Final technical report

    SciTech Connect

    Parker, J.

    1987-01-28

    The object of this project is the establishment of procedures which would allow the practical production of solutions of organometallic compounds suitable for the deposition of conductive metal films at temperatures below 250/sup 0/C. Purdue University's Turner Laboratory developed the basic chemistry for the synthesis of these ''oxygen bridge'' organometallic compounds. A solution of a metal salt is combined with a solution of an ammonium (or amine) soap of an appropriate organic acid. The resulting product precipitate is cleaned, dried and dissolved in xylene. Control of reaction pH and reagent purity was essential in producing useful quantities of the organometallic compounds in better than 75% yields and at reasonable costs. Processes were developed for silver, bismuth, platinum, nickel, and gold organometallic products. The processes for the gold and platinum products remained difficult, giving low yields and evidence of poor product stability. It is anticipated that improvement in the removal of inorganic impurities from the product would enhance its stability. Thermal analyses were applied to the products to determine their decomposition characteristics, and rough cost studies were made to aid in comparisons with conventional metallization methods.

  3. Progress towards bioorthogonal catalysis with organometallic compounds.

    PubMed

    Völker, Timo; Dempwolff, Felix; Graumann, Peter L; Meggers, Eric

    2014-09-22

    The catalysis of bioorthogonal transformations inside living organisms is a formidable challenge--yet bears great potential for future applications in chemical biology and medicinal chemistry. We herein disclose highly active organometallic ruthenium complexes for bioorthogonal catalysis under biologically relevant conditions and inside living cells. The catalysts uncage allyl carbamate protected amines with unprecedented high turnover numbers of up to 270 cycles in the presence of water, air, and millimolar concentrations of thiols. By live-cell imaging of HeLa cells and with the aid of a caged fluorescent probe we could reveal a rapid development of intense fluorescence within the cellular cytoplasm and therefore support the proposed bioorthogonality of the catalysts. In addition, to illustrate the manifold applications of bioorthogonal catalysis, we developed a method for catalytic in-cell activation of a caged anticancer drug, which efficiently induced apoptosis in HeLa cells.

  4. Detection of Metal and Organometallic Compounds with Bioluminescent Bacterial Bioassays.

    PubMed

    Durand, M J; Hua, A; Jouanneau, S; Cregut, M; Thouand, G

    2015-10-17

    Chemical detection of metal and organometallic compounds is very specific and sensitive, but these techniques are time consuming and expensive. Although these techniques provide information about the concentrations of compounds, they fail to inform us about the toxicity of a sample. Because the toxic effects of metals and organometallic compounds are influenced by a multitude of environmental factors, such as pH, the presence of chelating agents, speciation, and organic matter, bioassays have been developed for ecotoxicological studies. Among these bioassays, recombinant luminescent bacteria have been developed over the past 20 years, and many of them are specific for the detection of metals and metalloids. These bioassays are simple to use, are inexpensive, and provide information on the bioavailable fraction of metals and organometals. Thus, they are an essential complementary tool for providing information beyond chemical analysis. In this chapter, we propose to investigate the detection of metals and organometallic compounds with bioluminescent bacterial bioassays and the applications of these bioassays to environmental samples. Graphical Abstract.

  5. A Review of the Tissue Residue Approach for Organic and Organometallic Compounds in Aquatic Organisms

    EPA Science Inventory

    This paper reviews the tissue residue approach (TRA) for toxicity assessment as it applies to organic chemicals and some organometallic compounds (tin, mercury, and lead). Specific emphasis was placed on evaluating key factors that influence interpretation of critical body resid...

  6. Group 9 organometallic compounds for therapeutic and bioanalytical applications.

    PubMed

    Ma, Dik-Lung; Chan, Daniel Shiu-Hin; Leung, Chung-Hang

    2014-12-16

    CONSPECTUS: Compared with organic small molecules, metal complexes offer several distinct advantages as therapeutic agents or biomolecular probes. Carbon atoms are typically limited to linear, trigonal planar, or tetrahedral geometries, with a maximum of two enantiomers being formed if four different substituents are attached to a single carbon. In contrast, an octahedral metal center with six different substituents can display up to 30 different stereoisomers. While platinum- and ruthenium-based anticancer agents have attracted significant attention in the realm of inorganic medicinal chemistry over the past few decades, group 9 complexes (i.e., iridium and rhodium) have garnered increased attention in therapeutic and bioanalytical applications due to their adjustable reactivity (from kinetically liable to substitutionally inert), high water solubility, stability to air and moisture, and relative ease of synthesis. In this Account, we describe our efforts in the development of group 9 organometallic compounds of general form [M(C(∧)N)2(N(∧)N)] (where M = Ir, Rh) as therapeutic agents against distinct biomolecular targets and as luminescent probes for the construction of oligonucleotide-based assays for a diverse range of analytes. Earlier studies by researchers had focused on organometallic iridium(III) and rhodium(III) half-sandwich complexes that show promising anticancer activity, although their precise mechanisms of action still remain unknown. More recently, kinetically-inert group 9 complexes have arisen as fascinating alternatives to organic small molecules for the specific targeting of enzyme activity. Research in our laboratory has shown that cyclometalated octahedral rhodium(III) complexes were active against Janus kinase 2 (JAK2) or NEDD8-activating enzyme (NAE) activity, or against NO production leading to antivasculogenic activity in cellulo. At the same time, recent interest in the development of small molecules as modulators of protein

  7. A golden future in medicinal inorganic chemistry: the promise of anticancer gold organometallic compounds.

    PubMed

    Bertrand, Benoît; Casini, Angela

    2014-03-21

    From wedding rings on fingers to stained glass windows, by way of Olympic medals, gold has been highly prized for millennia. Nowadays, organometallic gold compounds occupy an important place in the field of medicinal inorganic chemistry due to their unique chemical properties with respect to gold coordination compounds. In fact, several studies have proved that they can be used to develop highly efficient metal-based drugs with possible applications in the treatment of cancer. This Perspective summarizes the results obtained for different families of bioactive organometallic gold compounds including cyclometallated gold(iii) complexes with C,N-donor ligands, gold(I) and gold(I/III) N-heterocyclic (NHC) carbene complexes, as well as gold(I) alkynyl complexes, with promising anticancer effects. Most importantly, we will focus on recent developments in the field and discuss the potential of this class of organometallic compounds in relation to their versatile chemistry and innovative mechanisms of action.

  8. 40 CFR 721.10414 - Polycyclic polyamine diester organometallic compound (generic) (P-10-358).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polycyclic polyamine diester organometallic compound (generic) (P-10-358). 721.10414 Section 721.10414 Protection of Environment ENVIRONMENTAL... compound (generic) (P-10-358). (a) Chemical substance and significant new uses subject to reporting....

  9. 40 CFR 721.10414 - Polycyclic polyamine diester organometallic compound (generic) (P-10-358).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Polycyclic polyamine diester organometallic compound (generic) (P-10-358). 721.10414 Section 721.10414 Protection of Environment ENVIRONMENTAL... compound (generic) (P-10-358). (a) Chemical substance and significant new uses subject to reporting....

  10. 40 CFR 721.10414 - Polycyclic polyamine diester organometallic compound (generic) (P-10-358).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polycyclic polyamine diester organometallic compound (generic) (P-10-358). 721.10414 Section 721.10414 Protection of Environment ENVIRONMENTAL... compound (generic) (P-10-358). (a) Chemical substance and significant new uses subject to reporting....

  11. Organometallic Chemical Vapor Deposition Growth of Antimony Compounds

    NASA Astrophysics Data System (ADS)

    Chiang, Peng-Kuen

    This research is motivated by the desire to synthesize Sb III-V materials, including GaAs(,1-x)Sb(,x), InSb, and InAs(,1-x)Sb(,x). Ga-As-Sb system is known to have a significant solid phase miscibility gap from x = 0.2 to x = 0.8 at 600(DEGREES)C using a liquid phase epitaxy (LPE) growth technique. In this work, organometallic chemical vapor deposition (OM-CVD) has been shown to be a suitable growth technique for growing GaAs(,1-x)Sb(,x) alloys lying in the region of solid immiscibility. Conditions for growth of GaAs(,1-x)Sb(,x) layers with x as high as 0.7 on GaAs substrates are described for temperatures between 580 and 650(DEGREES)C. Effects of substrate orientation on growth characteristics are noted, and comparisons of growth on (511) and (100) GaAs faces are made. The experimental results indicate that growth is being controlled by surface reaction kinetics. A simple model based on kinetic control is presented. InSb is one of the most extensively examined semiconductors because of the small energy bandgap which is suitable for 3-5 (mu)m wavelength detection, and it also has highest mobility of any III-V compounds. OM-CVD has been used to epitaxially grow high quality InSb for the first time in this work. InSb with excellent morphology was achieved on both (100) and (111)B InSb substrates. The measured electron mobility at 300(DEGREES)K of undoped InSb grown on (100) GaAs semi-insulating substrates was 40,000 cm('2)/V -sec at a carrier concentration of N(,D)-N(,A) = 1.2 x 10('15)cm(' -3) has been measured at 77(DEGREES)K.Experimental data suggests that a dislocation scattering mechanism represents a significant mobility limiting process. InAs(,1-x)Sb(,x), with x (TURN) 0.6, has the lowest bandgap (=0.1 eV at 300(DEGREES)K) of any of the III-V ternary compounds. This bandgap is suitable for detectors in the 8-12 (mu)m wavelength region where an atmosphere window exists. So far, InAs(,1-x)Sb(,x) with 0.55 < x < 0.75 has not been achieved by LPE and molecular

  12. Model for the Vaporization of Mixed Organometallic Compounds in the Metalorganic Chemical Vapor Deposition of High Temperature Superconducting Films

    NASA Technical Reports Server (NTRS)

    Meng, Guangyao; Zhou, Gang; Schneider, Roger L.; Sarma, Bimal K.; Levy, Moises

    1993-01-01

    A model of the vaporization and mass transport of mixed organometallics from a single source for thin film metalorganic chemical vapor deposition is presented. A stoichiometric gas phase can be obtained from a mixture of the organometallics in the desired mole ratios, in spite of differences in the volatilities of the individual compounds. Proper film composition and growth rates are obtained by controlling the velocity of a carriage containing the organometallics through the heating zone of a vaporizer.

  13. Using Molecular Modeling in Teaching Group Theory Analysis of the Infrared Spectra of Organometallic Compounds

    ERIC Educational Resources Information Center

    Wang, Lihua

    2012-01-01

    A new method is introduced for teaching group theory analysis of the infrared spectra of organometallic compounds using molecular modeling. The main focus of this method is to enhance student understanding of the symmetry properties of vibrational modes and of the group theory analysis of infrared (IR) spectra by using visual aids provided by…

  14. Organometallic Compounds and Polymers with Second and Third Order Nonlinear Optical Properties

    DTIC Science & Technology

    1993-05-06

    Nonlinear Optical Properties of Inorganic Coordination Polymers . William Chiang, Mark E. Thompson, Donna Van Engen , "Organic Materials for Nonlinear...Organometallic Compounds and Polymers with Second and Third Order Nonlinear Optical Pro. -c.AUTHOR(S) 61102F 2303 All Mark E. Thompson, PI 7. PERFORMING...scale Sc -Cr $5 Fe > Co. Polar coordination polymers were prepared in which excellent polar order was found in the polyermic chains. however, the

  15. Mössbauer effect studies on organometallic237Np-compounds

    NASA Astrophysics Data System (ADS)

    Adrian, G.; Appel, H.; Bohlander, R.; Haffner, H.; Kanellakopulos, B.

    1988-02-01

    A series of organometallic compounds of tetravalent Neptunium was studied by Moessbauer methods. Three of them will be presented here. Their molecular structure is close to C3v symmetry. The data were parameterised on the basis of an anisotropic paramagnetic relaxation model and will be interpreted for each individual compound. In general it can be stated that distortions from axially symmetric hyperfine parameters were observed, no magnetic ordering occured at all temperatures above 1.5 K and anisotropic relaxation frequencies had to be introduced to fit the spectra.

  16. Absorption of organic compounds and organometallics on ceramic substrates for wear reduction

    SciTech Connect

    Kennedy, P.J.; Agarwala, V.S.

    1996-12-31

    The concept of employing thermally stable compounds (that is, metal oxides) as high temperature vapor phase ceramic lubricants was investigated. A major part of this study was devoted to the development of various calorimetric and tribological techniques that could be used to determine interfacial reactions between thermally stable compounds and ceramic substrates such as zirconia and alumina. This interaction is pivotal in understanding the mechanism of high temperature lubricity. The approach consisted of selecting low sublimation temperature materials and measuring their thermodynamic interactions as vapors with the ceramic substrates. The materials studied included two easily sublimable organic compounds (that is, naphthalene and salicylic acid) and several organometallics (for example, copper phthalocyanine). Thermodynamic data such as heat of adsorption, packing density, and reversibility of the adsorption were obtained on some of these compounds and were related to wear characteristics. All of these compounds provided effective lubrication at room temperature. Copper phthalocyanine was an effective lubricant at temperatures up to 400 C.

  17. Systems and methods for solar energy storage, transportation, and conversion utilizing photochemically active organometallic isomeric compounds and solid-state catalysts

    DOEpatents

    Vollhardt, K. Peter C.; Segalman, Rachel A; Majumdar, Arunava; Meier, Steven

    2015-02-10

    A system for converting solar energy to chemical energy, and, subsequently, to thermal energy includes a light-harvesting station, a storage station, and a thermal energy release station. The system may include additional stations for converting the released thermal energy to other energy forms, e.g., to electrical energy and mechanical work. At the light-harvesting station, a photochemically active first organometallic compound, e.g., a fulvalenyl diruthenium complex, is exposed to light and is photochemically converted to a second, higher-energy organometallic compound, which is then transported to a storage station. At the storage station, the high-energy organometallic compound is stored for a desired time and/or is transported to a desired location for thermal energy release. At the thermal energy release station, the high-energy organometallic compound is catalytically converted back to the photochemically active organometallic compound by an exothermic process, while the released thermal energy is captured for subsequent use.

  18. Cyclopentadienyl-ruthenium(II) and iron(II) organometallic compounds with carbohydrate derivative ligands as good colorectal anticancer agents.

    PubMed

    Florindo, Pedro R; Pereira, Diane M; Borralho, Pedro M; Rodrigues, Cecília M P; Piedade, M F M; Fernandes, Ana C

    2015-05-28

    New ruthenium(II) and iron(II) organometallic compounds of general formula [(η(5)-C5H5)M(PP)Lc][PF6], bearing carbohydrate derivative ligands (Lc), were prepared and fully characterized and the crystal structures of five of those compounds were determined by X-ray diffraction studies. Cell viability of colon cancer HCT116 cell line was determined for a total of 23 organometallic compounds and SAR's data analysis within this library showed an interesting dependency of the cytotoxic activity on the carbohydrate moiety, linker, phosphane coligands, and metal center. More importantly, two compounds, 14Ru and 18Ru, matched oxaliplatin IC50 (0.45 μM), the standard metallodrug used in CC chemotherapeutics, and our leading compound 14Ru was shown to be significantly more cytotoxic than oxaliplatin to HCT116 cells, triggering higher levels of caspase-3 and -7 activity and apoptosis in a dose-dependent manner.

  19. Analysis of the mechanism of action of potent antibacterial hetero-tri-organometallic compounds: a structurally new class of antibiotics.

    PubMed

    Wenzel, Michaela; Patra, Malay; Senges, Christoph Helmut Rudi; Ott, Ingo; Stepanek, Jennifer Janina; Pinto, Antonio; Prochnow, Pascal; Vuong, Cuong; Langklotz, Sina; Metzler-Nolte, Nils; Bandow, Julia Elisabeth

    2013-07-19

    Two hetero-tri-organometallic compounds with potent activity against Gram-positive bacteria including multi-resistant Staphylococcus aureus (MRSA) were identified. The compounds consist of a peptide nucleic acid backbone with an alkyne side chain, substituted with a cymantrene, a (dipicolyl)Re(CO)3 moiety, and either a ferrocene (FcPNA) or a ruthenocene (RcPNA). Comparative proteomic analysis indicates the bacterial membrane as antibiotic target structure. FcPNA accumulation in the membrane was confirmed by manganese tracing with atomic absorption spectroscopy. Both organometallics disturbed several essential cellular processes taking place at the membrane such as respiration and cell wall biosynthesis, suggesting that the compounds affect membrane architecture. Correlating with enhanced antibacterial activity, oxidative stress was induced only by the ferrocene-substituted compound. The organometallics described here target the cytoplasmic membrane, a clinically proven antibacterial target structure, feature a bactericidal but non-bacteriolytic mode of action and limited cytotoxicity within the limits of solubility. Thus, FcPNA represents a promising lead structure for the development of a new synthetic class of antibiotics.

  20. Theoretical Study of Indium Compounds of Interest for Organometallic Chemical Vapor Deposition

    NASA Technical Reports Server (NTRS)

    Cardelino, B. H.; Moore, C. E.; Cardelino, C. A.; Frazier, D. O.; Backmann, K. J.

    2000-01-01

    The structural. electronic and therinochemical properties of indium compounds which are of interest in halide transport and organometallic chemical vapor deposition processes have been studied by ab initio and statistical mechanics methods. The compounds reported include: indium halides and hydrides (InF, InCl, InCl3, InH, InH2, InH3); indium clusters (In2, In3); methylindium, dimethylindium, and their hydrogen derivatives [In(CH3), In(CH3)H, In(CH3)H2, In(CH3)2, In(CH3)2H]; dimethyl-indium dimer [In2(CH3)4], trimethyl-indium [In(CH3)3]; dehydrogenated methyl, dimethyl and trimethylindium [In(CH3)2CH2, In(CH3)CH2, In(CH2)], trimethylindium adducts with ammonia, trimethylamine and hydrazine [(CH3)3In:NH3, (CH3)3In:N(CH3)3, (CH3)3In:N(H2)N(H2)]; dimethylamino-indium and methylimino-indium [In(CH3)2(NH2), In(CH3)(NH)]; indium nitride and indium nitride dimer (InN, In2N2), indium phosphide, arsenide and antimonide ([InP, InAs, InSb). The predicted electronic properties are based on density functional theory calculations; the calculated thermodynamic properties are reported following the format of the JANAF (Joint Army, Navy, NASA, Air Force) Tables. Equilibrium compositions at two temperatures (298 and 1000 K) have been analyzed for groups of competing simultaneous reactions.

  1. Organometallic chemistry in non-classical environments.

    PubMed

    Dyson, Paul J

    2011-01-01

    A summary of our on-going research on organometallic chemistry is provided with an emphasis on the function, reactivity and mechanisms of organometallic compounds in water, ionic liquids and in living systems. The role of organometallic compounds in both catalysis and medicinal chemistry are briefly described.

  2. Protective Actions of 17β-Estradiol and Progesterone on Oxidative Neuronal Injury Induced by Organometallic Compounds

    PubMed Central

    Ishihara, Yasuhiro; Takemoto, Takuya; Yamazaki, Takeshi

    2015-01-01

    Steroid hormones synthesized in and secreted from peripheral endocrine glands pass through the blood-brain barrier and play a role in the central nervous system. In addition, the brain possesses an inherent endocrine system and synthesizes steroid hormones known as neurosteroids. Increasing evidence shows that neuroactive steroids protect the central nervous system from various harmful stimuli. Reports show that the neuroprotective actions of steroid hormones attenuate oxidative stress. In this review, we summarize the antioxidative effects of neuroactive steroids, especially 17β-estradiol and progesterone, on neuronal injury in the central nervous system under various pathological conditions, and then describe our recent findings concerning the neuroprotective actions of 17β-estradiol and progesterone on oxidative neuronal injury induced by organometallic compounds, tributyltin, and methylmercury. PMID:25815107

  3. Spectroscopic studies of organometallic compounds on single crystal metal surfaces: Surface acetylides of silver (110)

    NASA Astrophysics Data System (ADS)

    Madix, Robert J.

    The nature of compounds formed by the reaction of organic molecules with metal surfaces can be studied with a battery of analytical methods based on both physicals and chemical understanding. In this paper the application of UPS, XPS, LEED and EELS as well as temperature programmed reaction spectroscopy (TPRS) and chemical titration methods to the characterization of surface complexes is discussed. Particular emphasis is given to the reaction of acetylene with a single crystal surface of silver, Ag(110). Previous work has shown that this surface, when clean, is unreactive to hydrocarbons, alcohols and carboxylic acids under ultra high vacuum conditions. Preadsorption of oxygen, however, renders the surface reactive, and a wide variety of organometallic surface compounds can be formed. As expected then, no stable adsorption state and no reaction was observed with clean Ag(110) following room temperature exposure to acetylene. Following exposure at 150 K, however, a weekly bound chemisorption state was observed to desorb at 195 K, indicating a binding energy to the surface of approximately 12 kcal/gmole. Reaction with preadsorbed oxygen gave water formulation upon dosing and produced surface intermediates which yeilded two acetylene desorption states at 195 and 175 K. Heating above 300 K to completely desorb the higher temperature state produced new, well-defined LEED Features due to residual surface carbon which disappeared when the surface was heated above 550 K. Clearly, there were distinc changes in the nature of the absorbed layer at 195, 300 and 550 K. These changes were reflected in XPS. For the weakly chemisorbed acetylene a large C(ls) peak at 285.6 eV with a small, broad, indistinc shoulder at higher binding energy (288.2) was observed. The spectrum of the species following acetylene desorption at 275 K, however, showed the formulation of a large C(ls) peak at 283.6 eV in addition to peaks characteristics of the weakly chemisorbed state. This result

  4. Rationalization of the inhibition activity of structurally related organometallic compounds against the drug target cathepsin B by DFT.

    PubMed

    Casini, Angela; Edafe, Fabio; Erlandsson, Mikael; Gonsalvi, Luca; Ciancetta, Antonella; Re, Nazzareno; Ienco, Andrea; Messori, Luigi; Peruzzini, Maurizio; Dyson, Paul J

    2010-06-21

    A series of organometallic compounds of general formula [(arene)M(PTA)(n)X(m)]Y (arene = eta(6)-C(10)H(14), eta-C(5)Me(5)); M = Ru(ii), Os(ii), Rh(iii) and Ir(iii); X = Cl, mPTA; Y = OTf, PF(6)) have been screened for their cytotoxicity and ability to inhibit cathepsin B in vitro, in comparison to the antimetastatic compound NAMI-A. The Ru and Os analogues and NAMI-A showed similar enzyme inhibition properties (with IC(50) values in the low muM range), whereas the Rh(iii) and Ir(iii) compounds were inactive. In order to build up a rational for the observed differences, DFT calculations of the metal complexes adducts with N-acetyl-l-cysteine-N'-methylamide, a mimic for the Cys residue in the cathepsin B active site, were performed to provide insights into binding thermodynamics in solution. Initial structure-activity relationships have been defined with the calculated binding energies of the M-S bonds correlating well with the observed inhibition properties of the compounds.

  5. Assessment of background concentrations of organometallic compounds (methylmercury, ethyllead and butyl- and phenyltin) in French aquatic environments.

    PubMed

    Cavalheiro, Joana; Sola, Cristina; Baldanza, Julie; Tessier, Emmanuel; Lestremau, François; Botta, Fabrizio; Preud'homme, Hugues; Monperrus, Mathilde; Amouroux, David

    2016-05-01

    The aim of this work is to estimate background concentrations of organometallic compounds, such as tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), triphenyltin (TPhT), diphenyltin (DPhT), monophenyltin (MPhT), methylmercury (MeHg), inorganic mercury (iHg) and diethyllead (Et2Pb) in the aquatic environment at the French national scale. Both water and sediment samples were collected all over the country, resulting in 152 water samples and 123 sediment samples collected at 181 sampling points. Three types of surface water bodies were investigated: rivers (140 sites), lakes (19 sites) and coastal water (42 sites), spread along the 11 French river basins. The choice of sites was made on the basis of previous investigation results and the following target criteria: reference, urban sites, agricultural and industrial areas. The analytical method was properly validated for both matrices prior to analysis, resulting in low limits of quantification (LOQ), good precision and linearity in agreement with the Water Framework Directive demands. The results were first evaluated as a function of their river basins, type of surrounding pressure and water bodies. Later, background concentrations at the French national scale were established for both water and sediment matrices, as well as their threshold, i.e., the concentration that distinguishes background from anomalies or contaminations. Background concentrations in water are ranging between <0.04-0.14 ng Hg. L(-1) for MeHg, <0.14-2.10 ng Hg. L(-1) for iHg, <1.0-8.43 ng Pb. L(-1) for Et2Pb and 0.49-151 ng Sn. L(-1), <0.08-3.04 ng Sn. L(-1) and <0.08-0.25 ng Sn. L(-1) for MBT, DBT and TBT, respectively. For sediments, background concentrations were set as <0.09-1.11 ng Hg. g(-1) for MeHg, <0.06-24.3 ng Pb. g(-1) for Et2Pb and <1.4-13.4 ng Sn. g(-1), <0.82-8.54 ng Sn. g(-1), <0.25-1.16 ng Sn. g(-1) and <0.08-0.61 ng Sn. g(-1) for MBT, DBT, TBT and DPhT, respectively. TBT occurs in higher concentrations than the available

  6. Studies of the hydrogenation of small unsaturated molecules using organometallic cluster compounds as catalysts

    SciTech Connect

    Not Available

    1981-01-01

    Progress under contract DE-AC02-78ER04900 and plans for continued investigations of the reactivity of transition metal hydride cluster compounds with small heteronuclear unsaturated molecules are described. Research will include further elucidation of the mechanisms of hydrogen transfer from metal atoms to unsaturated substrates and studies of the structure and bonding of partially hydrogenated substrates coordinated to polynuclear metal centers. Investigations of the reactivity of the bridging hydride ligand and the chemistry of alkyl groups in clusters are planned. The development of heteronuclear clusters as homogeneous CO hydrogenation catalysts will be attempted.

  7. Distribution of organic and organometallic compounds in sediments from the Louisianian Province

    SciTech Connect

    Maruya, K.; Ertel, J.; Loganathan, B.

    1996-12-31

    In 1994, over 200 sediment samples were collected in accordance with EPA`s EMAP probabilistic sampling protocol from coastal and estuarine areas in the Louisianian Province (Gulf of Mexico). These samples represent a homogenate of 3 to 5 grabs from which the top 2 cm of surficial sediments were extracted. These samples were frozen and shipped to the Skidaway Institute of Oceanography for analysis of metal and organic constituents. Frozen sediments were freeze dried and up to 40 g were soxhlet extracted with CH{sub 2}Cl{sub 2}. This extract was then divided into several sub-aliquots for analysis of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides, organophosphate pesticides and organotin (butyl- and phenyltins) compounds. Interferences were removed using packed column chromatography and split extracts were analyzed by GC with the appropriate detection technique.

  8. Structure--activity relationship and mode of action of N-(6-ferrocenyl-2-naphthoyl) dipeptide ethyl esters: novel organometallic anticancer compounds.

    PubMed

    Mooney, Aine; Tiedt, Rachel; Maghoub, Thamir; O'Donovan, Norma; Crown, John; White, Blánaid; Kenny, Peter T M

    2012-06-14

    In this article, we report the findings of a comprehensive structure-activity relationship study of N-(6-ferrocenyl-2-naphthoyl) dipeptide ethyl esters, in which novel analogues were designed, synthesized, and evaluated in vitro for antiproliferative effect. Two new compounds, 2 and 16, showed potent nanomolar activity in the H1299 NSCLC cell line, with exceptional IC(50) values of 0.13 and 0.14 μM, respectively. These compounds were also found to have significant activity in the Sk-Mel-28 malignant melanoma cell line (IC(50) values of 1.10 and 1.06 μM, respectively). Studies were also conducted to elucidate the mode of action of these novel organometallic anticancer compounds. Cell cycle analysis in the H1299 cell line suggests these compounds induce apoptosis, while guanine oxidation studies confirm that 2 is capable of generating oxidative damage via a ROS-mediated mechanism.

  9. Organometallic Radiopharmaceuticals

    NASA Astrophysics Data System (ADS)

    Alberto, Roger

    Although molecular imaging agents have to be synthesized ultimately from aqueous solutions, organometallic complexes are becoming more and more important as flexible yet kinetically stable building blocks for radiopharmaceutical drug discovery. The diversity of ligands, targets, and targeting molecules related to these complexes is an essential base for finding novel, noninvasive imaging agents to diagnose and eventually treat widespread diseases such as cancer. This review article covers the most important findings toward these objectives accomplished during the past 3-4 years. The two major available organometallic building blocks will be discussed in the beginning together with constraints for market introduction as imposed by science and industry. Since targeting radiopharmaceuticals are a major focus of current research in molecular imaging, attempts toward so-called technetium essential radiopharmaceuticals will be briefly touched in the beginning followed by the main discussion about the labeling of targeting molecules such as folic acid, nucleosides, vitamins, carbohydrates, and fatty acids. At the end, some new strategies for drug discovery will be introduced together with results from organometallic chemistry in water. The majority of the new results have been achieved with the [99mTc(OH2)3(CO)3]+ complex which will, though not exclusively, be a focus of this review.

  10. Phase Transition Enthalpy Measurements of Organic and Organometallic Compounds and Ionic Liquids. Sublimation, Vaporization, and Fusion Enthalpies from 1880 to 2015. Part 2. C11-C192

    NASA Astrophysics Data System (ADS)

    Acree, William; Chickos, James S.

    2017-03-01

    The second part of this compendium concludes with a collection of phase change enthalpies of organic molecules inclusive of C11-C192 reported over the period 1880-2015. Also included are phase change enthalpies including fusion, vaporization, and sublimation enthalpies for organometallic, ionic liquids, and a few inorganic compounds. Paper I of this compendium, published separately, includes organic compounds from C1 to C10 and describes a group additivity method for evaluating solid, liquid, and gas phase heat capacities as well as temperature adjustments of phase changes. Paper II of this compendium also includes an updated version of a group additivity method for evaluating total phase change entropies which together with the fusion temperature can be useful in estimating total phase change enthalpies. Other uses include application in identifying potential substances that either form liquid or plastic crystals or exhibit additional phase changes such as undetected solid-solid transitions or behave anisotropically in the liquid state.

  11. TRIFLUOROMETHYL COMPOUNDS OF GERMANIUM

    DTIC Science & Technology

    FLUORIDES, *GERMANIUM COMPOUNDS, *HALIDES, *ORGANOMETALLIC COMPOUNDS, ALKYL RADICALS, ARSENIC COMPOUNDS, CHEMICAL BONDS, CHEMICAL REACTIONS ...CHLORIDES, CHLORINE COMPOUNDS, HYDROLYSIS, IODIDES, METHYL RADICALS, POTASSIUM COMPOUNDS, PYROLYSIS, STABILITY, SYNTHESIS, TIN COMPOUNDS.

  12. Organometallic neptunium(III) complexes.

    PubMed

    Dutkiewicz, Michał S; Farnaby, Joy H; Apostolidis, Christos; Colineau, Eric; Walter, Olaf; Magnani, Nicola; Gardiner, Michael G; Love, Jason B; Kaltsoyannis, Nikolas; Caciuffo, Roberto; Arnold, Polly L

    2016-08-01

    Studies of transuranic organometallic complexes provide a particularly valuable insight into covalent contributions to the metal-ligand bonding, in which the subtle differences between the transuranium actinide ions and their lighter lanthanide counterparts are of fundamental importance for the effective remediation of nuclear waste. Unlike the organometallic chemistry of uranium, which has focused strongly on U(III) and has seen some spectacular advances, that of the transuranics is significantly technically more challenging and has remained dormant. In the case of neptunium, it is limited mainly to Np(IV). Here we report the synthesis of three new Np(III) organometallic compounds and the characterization of their molecular and electronic structures. These studies suggest that Np(III) complexes could act as single-molecule magnets, and that the lower oxidation state of Np(II) is chemically accessible. In comparison with lanthanide analogues, significant d- and f-electron contributions to key Np(III) orbitals are observed, which shows that fundamental neptunium organometallic chemistry can provide new insights into the behaviour of f-elements.

  13. Organometallic neptunium(III) complexes

    NASA Astrophysics Data System (ADS)

    Dutkiewicz, Michał S.; Farnaby, Joy H.; Apostolidis, Christos; Colineau, Eric; Walter, Olaf; Magnani, Nicola; Gardiner, Michael G.; Love, Jason B.; Kaltsoyannis, Nikolas; Caciuffo, Roberto; Arnold, Polly L.

    2016-08-01

    Studies of transuranic organometallic complexes provide a particularly valuable insight into covalent contributions to the metal-ligand bonding, in which the subtle differences between the transuranium actinide ions and their lighter lanthanide counterparts are of fundamental importance for the effective remediation of nuclear waste. Unlike the organometallic chemistry of uranium, which has focused strongly on UIII and has seen some spectacular advances, that of the transuranics is significantly technically more challenging and has remained dormant. In the case of neptunium, it is limited mainly to NpIV. Here we report the synthesis of three new NpIII organometallic compounds and the characterization of their molecular and electronic structures. These studies suggest that NpIII complexes could act as single-molecule magnets, and that the lower oxidation state of NpII is chemically accessible. In comparison with lanthanide analogues, significant d- and f-electron contributions to key NpIII orbitals are observed, which shows that fundamental neptunium organometallic chemistry can provide new insights into the behaviour of f-elements.

  14. Organometallic Titanocene–Gold Compounds as Potential Chemotherapeutics in Renal Cancer. Study of their Protein Kinase Inhibitory Properties

    PubMed Central

    2015-01-01

    Early–late transition metal TiAu2 compounds [(η-C5H5)2Ti{OC(O)CH2PPh2AuCl}2] (3) and new [(η-C5H5)2Ti{OC(O)-4-C6H4PPh2AuCl}2] (5) were evaluated as potential anticancer agents in vitro against renal and prostate cancer cell lines. The compounds were significantly more effective than monometallic titanocene dichloride and gold(I) [{HOC(O)RPPh2}AuCl] (R = −CH2– 6, −4-C6H4– 7) derivatives in renal cancer cell lines, indicating a synergistic effect of the resulting heterometallic species. The activity on renal cancer cell lines (for 5 in the nanomolar range) was considerably higher than that of cisplatin and highly active titanocene Y. Initial mechanistic studies in Caki-1 cells in vitro coupled with studies of their inhibitory properties on a panel of 35 kinases of oncological interest indicate that these compounds inhibit protein kinases of the AKT and MAPKAPK families with a higher selectivity toward MAPKAPK3 (IC503 = 91 nM, IC505 = 117 nM). The selectivity of the compounds in vitro against renal cancer cell lines when compared to a nontumorigenic human embryonic kidney cell line (HEK-293T) and the favorable preliminary toxicity profile on C57black6 mice indicate that these compounds (especially 5) are excellent candidates for further development as potential renal cancer chemotherapeutics. PMID:25435644

  15. s-Block organometallics: analysis of ion-association and noncovalent interactions on structure and function in benzyl-based compounds.

    PubMed

    Torvisco, Ana; Ruhlandt-Senge, Karin

    2011-12-19

    The organometallic chemistry of alkali and alkaline-earth metals has been marred by synthetic setbacks because of their high reactivity. Advances in their synthesis and a better understanding of the stabilization effects of ligands and coligands have resulted in the revolution of s-block organometallics. Among those, benzyl-based derivatives have played a key role in developing this chemistry because factors such as the ligand size, charge delocalization, and introduction of electronic parameters along with metal effects can be analyzed. This article will focus on s-block benzylates and di- and triphenylmethanide derivatives with specific emphasis on the factors that stabilize the highly reactive metal species.

  16. Application of imaging spectroscopic reflectometry for characterization of gold reduction from organometallic compound by means of plasma jet technology

    NASA Astrophysics Data System (ADS)

    Vodák, Jiří; Nečas, David; Pavliňák, David; Macak, Jan M.; Řičica, Tomáš; Jambor, Roman; Ohlídal, Miloslav

    2017-02-01

    This work presents a new application of imaging spectroscopic reflectometry to determine a distribution of metallic gold in a layer of an organogold precursor which was treated by a plasma jet. Gold layers were prepared by spin coating from a solution of the precursor containing a small amount of polyvinylpyrrolidone on a microscopy glass, then they were vacuum dried. A difference between reflectivity of metallic gold and the precursor was utilized by imaging spectroscopic reflectometry to create a map of metallic gold distribution using a newly developed model of the studied sample. The basic principle of the imaging spectroscopic reflectometry is also shown together with the data acquisition principles. XPS measurements and microscopy observations were made to complete the imaging spectroscopic reflectometry results. It is proved that the imaging spectroscopic reflectometry represents a new method for quantitative evaluation of local reduction of metallic components from metaloorganic compounds.

  17. Group IV organometallic compounds based on dianionic "pincer" ligands: synthesis, characterization, and catalytic activity in intramolecular hydroamination reactions.

    PubMed

    Luconi, Lapo; Rossin, Andrea; Motta, Alessandro; Tuci, Giulia; Giambastiani, Giuliano

    2013-04-08

    Neutral Zr(IV) and Hf(IV) diamido complexes stabilized by unsymmetrical dianionic N,C,N' pincer ligands have been prepared through the simplest and convenient direct metal-induced Caryl-H bond activation. Simple ligand modification has contributed to highlight the non-innocent role played by the donor atom set in the control of the cyclometallation kinetics. The as-prepared bis-amido catalysts were found to be good candidates for the intramolecular hydroamination/cyclization of primary aminoalkenes. The ability of these compounds to promote such a catalytic transformation efficiently (by providing, in some cases, fast and complete substrate conversion at room temperature) constitutes a remarkable step forward toward catalytic systems that can operate at relatively low catalyst loading and under milder reaction conditions. Kinetic studies and substrate-scope investigations, in conjunction with preliminary DFT calculations on the real systems, were used to elucidate the effects of the substrate substitution on the catalyst performance and to support the most reliable mechanistic path operative in the hydroamination reaction.

  18. Organometallic Chemistry of Molybdenum.

    ERIC Educational Resources Information Center

    Lucas, C. Robert; Walsh, Kelly A.

    1987-01-01

    Suggests ways to avoid some of the problems students have learning the principles of organometallic chemistry. Provides a description of an experiment used in a third-year college chemistry laboratory on molybdenum. (TW)

  19. Chromo- and Fluorogenic Organometallic Sensors

    NASA Astrophysics Data System (ADS)

    Fletcher, Nicholas C.; Lagunas, M. Cristina

    Compounds that change their absorption and/or emission properties in the presence of a target ion or molecule have been studied for many years as the basis for optical sensing. Within this group of compounds, a variety of organometallic complexes have been proposed for the detection of a wide range of analytes such as cations (including H+), anions, gases (e.g. O2, SO2, organic vapours), small organic molecules, and large biomolecules (e.g. proteins, DNA). This chapter focuses on work reported within the last few years in the area of organometallic sensors. Some of the most extensively studied systems incorporate metal moieties with intense long-lived metal-to-ligand charge transfer (MLCT) excited states as the reporter or indicator unit, such as fac-tricarbonyl Re(I) complexes, cyclometallated Ir(III) species, and diimine Ru(II) or Os(II) derivatives. Other commonly used organometallic sensors are based on Pt-alkynyls and ferrocene fragments. To these reporters, an appropriate recognition or analyte-binding unit is usually attached so that a detectable modification on the colour and/or the emission of the complex occurs upon binding of the analyte. Examples of recognition sites include macrocycles for the binding of cations, H-bonding units selective to specific anions, and DNA intercalating fragments. A different approach is used for the detection of some gases or vapours, where the sensor's response is associated with changes in the crystal packing of the complex on absorption of the gas, or to direct coordination of the analyte to the metal centre.

  20. Chemistry related to semiconductor growth involving organometallics

    NASA Astrophysics Data System (ADS)

    Husk, G. R.; Jones, K. A.; Paur, R. J.; Prater, J. T.

    1990-05-01

    OMVPE (OrganoMetallic Vapor-Phase Epitaxy) technology requirements for III-V compounds and chemistry related to semiconductor growth involving organometallics are discussed. The following subject areas are covered: semiconductor device requirements; Army II-VI deposition program/MOMBE (Metal Organic Molecular Beam Epitaxy) for IR detector applications; epitaxial growth of III-V's and II-VI's using organometallics; electrical device requirements; environmental and safety issues in MOVPE; quantum chemistry of vapor phase; carbon doping and selective epitaxy (tailoring growth chemistry in MOVPE); TBA/TBP precursors in GaAs and InP MOCVD; single source precursors for III-V OMCVD (OrganoMetallic Chemical Vapor Deposition) growth; alternate sources for MOMBE of AlGaAs; mechanism of incorporation of impurities and analysis of carbon contamination; growth on nonplanar and patterned substrates; CBE growth mechanisms; TriMethylamine Alane (a new robust precursor for MOMBE growth of AlGaAs); real-time determinations of OMCVD growth kinetics on GaAs by reflectance-difference spectroscopy; photoreflectance measurements; growth and doping mechanisms for HgCdTe; photoassisted CBE (Chemical Beam Epitaxy) of CdTe and HgCdTe alloys; in-situ analysis of ZnSe growth by OMCVD using X-ray scattering; biodegradation of GaAs IC chips and wafers; detailed models of compound semiconductor growth by MOCVD; gas phase probes of GaAs cluster chemistry; photodecomposition of organometallic compounds at 193 nm; manufacturing issues in MOCVD compound semiconductor technology.

  1. Tailored Organometallic Polymers

    DTIC Science & Technology

    1993-01-31

    ORGANOMETALLIC POLYMERS (Unclassified) 12. PERSONAL AUTHOR(S) R.M. Laine, C. Viney and R.J.P. Corriu (Addresses listed on following page) 13a. TYPE OF...MI 48109-2136 Christopher Viney Center for Bioengineering WD-12 University of Washington Seattle, W,’ 98195 Reproduced From Best Available Copy Robert...RECOGNIZING SUPPORT FROM CONTRACT F49620-89-C-0059 R.M. Laine and C. Viney welcome requests for reprints of articles that they authored. 1

  2. Sterically Hindered Square-Planar Nickel(II) Organometallic Complexes: Preparation, Characterization, and Substitution Behavior

    ERIC Educational Resources Information Center

    Martinez, Manuel; Muller, Guillermo; Rocamora, Merce; Rodriguez, Carlos

    2007-01-01

    The series of experiments proposed for advanced undergraduate students deal with both standard organometallic preparative methods in dry anaerobic conditions and with a kinetic study of the mechanisms operating in the substitution of square-planar complexes. The preparation of organometallic compounds is carried out by transmetallation or…

  3. Optimisation of a headspace-solid-phase micro-extraction method for simultaneous determination of organometallic compounds of mercury, lead and tin in water by gas chromatography-tandem mass spectrometry.

    PubMed

    Beceiro-González, E; Guimaraes, A; Alpendurada, M F

    2009-07-17

    In this work, a headspace-solid-phase micro-extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) method for multielemental speciation of organometallic compounds of mercury, lead and tin in water samples was upgraded by the introduction of tandem mass spectrometry (MS/MS) as detection technique. The analytical method is based on the ethylation with NaBEt(4) and simultaneous headspace-solid-phase micro-extraction of the derivative compounds followed by GC-MS/MS analysis. The main experimental parameters influencing the extraction efficiency such as derivatisation time, extraction time and extraction temperature were optimized. The overall optimum extraction conditions were the following: a 50 microm/30 microm divinyl-benzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) SPME fibre, 150 min derivatisation time, 15 min extraction time, sample agitation at 250 rpm and 40 degrees C extraction temperature. The analytical characteristics of the HS-SPME method combined with GC-MS and GC-MS/MS were evaluated. The combination of both techniques HS-SPME and GC-MS/MS allowed to attain lower limits of detection (4-33 ng l(-1)) than those obtained by HS-SPME-GC-MS (17-45 ng l(-1)). The proposed method presented good linear regression coefficients (r(2)>0.9970) and repeatability (4.8-21.0%) for all the compounds under study. The accuracy of the method measured as the average percentage recovery of the compounds in spiked river water and seawater samples was higher than 80% for all the compounds studied, except for monobutyltin in the river water sample. A study of the uncertainty associated with the analytical results was also carried out.

  4. Inorganic and Organometallic Polymers

    NASA Astrophysics Data System (ADS)

    Chandrasekhar, Vadapalli

    This textbook is intended to give an understanding of the basic principles that constitute the field of non-conventional polymers containing inorganic and organometalic units as the repeating units. Each chapter will be self-explanatory with a good background so that it can be easily understood at the senior undergraduate level. The principles involved in the preparation of these polymers, their characterisation and their applications will be discussed. Basic inorganic chemistry required for the understanding of each topic is presented so that the content of the chapter is readily understood.

  5. Luminescent Di and Polynuclear Organometallic Gold(I)-M (Au2, {Au2Ag}n and {Au2Cu}n) Compounds Containing Bidentate Phosphanes as Active Antimicrobial Agents

    PubMed Central

    Frik, Malgorzata; Jiménez, Josefina; Gracia, Ismael; Falvello, Larry R.; Abi-Habib, Sarya; Suriel, Karina; Muth, Theodore R.

    2012-01-01

    The reaction of new dinuclear gold(I) organometallic complexes containing mesityl ligands and bridging bidentate phosphanes [Au2(mes)2(μ-LL)] (LL = dppe: 1,2-Bis(di-phenylphosphano)ethane 1a, and water-soluble dppy: 1,2-Bis(di-3-pyridylphosphano)ethane 1b) with Ag+ and Cu+ lead to the formation of a family of heterometallic clusters with mesityl bridging ligands of the general formula [Au2M(μ-mes)2(μ-LL)]A (M = Ag, A = ClO4−, L-L = dppe 2a, dppy 2b; M = Ag, A = SO3CF3−, L-L = dppe 3a, dppy 3b; M = Cu, A = PF6−, L-L = dppe 4a, dppy 4b). The new compounds were characterized by different spectroscopic techniques and mass spectrometry The crystal structures of [Au2(mes)2(μ-dppy)] 1b and [Au2Ag(μ-mes)2(μ-dppe)]SO3CF3 3a were determined by a single-crystal X-ray diffraction study. 3a in solid state is not a cyclic trinuclear Au2Ag derivative but it gives an open polymeric structure instead, with the {Au2(μ-dppe)} fragments “linked” by Ag(μ-mes)2 units. The very short distances of 2.7559(6) Å (Au-Ag) and 2.9229(8) Å (Au-Au) are indicative of gold-silver (metallophillic) and aurophilic interactions. A systematic study of their luminescence properties revealed that all compounds are brightly luminescent in solid state, at room temperature (RT) and at 77 K, or in frozen DMSO solutions with lifetimes in the microsecond range and probably due to the self-aggregation of [Au2M(μ-mes)2(μ-LL)]+ units (M= Ag or Cu; LL= dppe or dppy) into an extended chain structure, through Au-Au and/or Au-M metallophylic interactions, as that observed for 3a. In solid state the heterometallic Au2M complexes with dppe (2a–4a) show a shift of emission maxima (from ca. 430 to the range of 520–540 nm) as compared to the parent dinuclear organometallic product 1a while the complexes with dppy (2b–4b) display a more moderate shift (505 for 1b to a max of 563 nm for 4b). More importantly, compound [Au2Ag(μ-mes)2(μ-dppy)]ClO4 2b resulted luminescent in diluted DMSO solution

  6. Preparation of activated carbons with mesopores by use of organometallics

    SciTech Connect

    Yamada, Yoshio; Yoshizawa, Noriko; Furuta, Takeshi

    1996-12-31

    Activated carbons are commercially produced by steam or CO{sub 2} activation of coal, coconut shell and so on. In general the carbons obtained give pores with a broad range of distribution. The objective of this study was to prepare activated carbons from coal by use of various organometallic compounds. The carbons were evaluated for pore size by nitrogen adsorption experiments.

  7. Organometallic Chemistry. Final Progress Report

    SciTech Connect

    2003-07-14

    The Gordon Research Conference (GRC) on Organometallic Chemistry was held at Salve Regina, Newport, Rhode Island, 7/21-26/02. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  8. Evidence for the involvement of 5f orbitals in the bonding and reactivity of organometallic actinide compounds: thorium(IV) and uranium(IV) bis(hydrazonato) complexes.

    PubMed

    Cantat, Thibault; Graves, Christopher R; Jantunen, Kimberly C; Burns, Carol J; Scott, Brian L; Schelter, Eric J; Morris, David E; Hay, P Jeffrey; Kiplinger, Jaqueline L

    2008-12-24

    Migratory insertion of diphenyldiazomethane into both metal-carbon bonds of the bis(alkyl) and bis(aryl) complexes (C(5)Me(5))(2)AnR(2) yields the first f-element bis(hydrazonato) complexes (C(5)Me(5))(2)An[eta(2)-(N,N')-R-N-N=CPh(2)](2) [An = Th, R = CH(3) (18), PhCH(2) (15), Ph (16); An = U, R = CH(3) (17), PhCH(2) (14)], which have been characterized by a combination of spectroscopy, electrochemistry, and X-ray crystallography. The two hydrazonato ligands adopt an eta(2)-coordination mode leading to 20-electron (for Th) and 22-electron (for U) complexes that have no transition-metal analogues. In fact, reaction of (C(5)H(5))(2)Zr(CH(3))(2) or (C(5)Me(5))(2)Hf(CH(3))(2) with diphenyldiazomethane is limited to the formation of the corresponding mono(hydrazonato) complex (C(5)R(5))(2)M[eta(2)-(N,N')-CH(3)-N-N=CPh(2)](CH(3)) (M = Zr, R = H or M = Hf, R = CH(3)). The difference in the reactivities of the group 4 metal complexes and the actinides was used as a unique platform for investigating in depth the role of 5f orbitals on the reactivity and bonding in actinide organometallic complexes. The electronic structure of the (C(5)H(5))(2)M[eta(2)-(N,N')-CH(3)-N-N=CH(2)](2) (M = Zr, Th, U) model complexes was studied using density functional theory (DFT) calculations and compared to experimental structural, electrochemical, and spectroscopic results. Whereas transition-metal bis(cyclopentadienyl) complexes are known to stabilize three ligands in the metallocene girdle to form saturated (C(5)H(5))(2)ML(3) species, in a bis(hydrazonato) system, a fourth ligand is coordinated to the metal center to give (C(5)H(5))(2)ML(4). DFT calculations have shown that 5f orbitals in the actinide complexes play a crucial role in stabilizing this fourth ligand by stabilizing both the sigma and pi electrons of the two eta(2)-coordinated hydrazonato ligands. In contrast, the stabilization of the hydrazonato ligands was found to be significantly less effective for the putative bis

  9. Potent organometallic osmium compounds induce mitochondria-mediated apoptosis and S-phase cell cycle arrest in A549 non-small cell lung cancer cells.

    PubMed

    van Rijt, Sabine H; Romero-Canelón, Isolda; Fu, Ying; Shnyder, Steve D; Sadler, Peter J

    2014-05-01

    The problems of acquired resistance associated with platinum drugs may be addressed by chemotherapeutics based on other transition metals as they offer the possibility of novel mechanisms of action. In this study, the cellular uptake and induction of apoptosis in A549 human non-small cell lung cancer cells of three promising osmium(II) arene complexes containing azopyridine ligands, [Os(η(6)-arene)(p-R-phenylazopyridine)X]PF6, where arene is p-cymene or biphenyl, R is OH or NMe2, and X is Cl or I, were investigated. These complexes showed time-dependent (4–48 h) potent anticancer activity with highest potency after 24 h (IC50 values ranging from 0.1 to 3.6 μM). Cellular uptake of the three compounds as quantified by ICP-MS, was independent of their logP values (hydrophobicity). Furthermore, maximum cell uptake was observed after 24 h, with evident cell efflux of the osmium after 48 and 72 h of exposure, which correlated with the corresponding IC50 values. The most active compound 2, [Os(η(6)-p-cymene)(NMe2-phenylazopyridine)I]PF6, was taken up by lung cancer cells predominately in a temperature-dependent manner indicating that energy-dependent mechanisms are important in the uptake of 2. Cell fractionation studies showed that all three compounds accumulated mainly in cellular membranes. Furthermore, compound 2 induced apoptosis and caused accumulation in the S-phase of the cell cycle. In addition, 2 induced cytochrome c release and alterations in mitochondrial membrane potential even after short exposure times, indicating that mitochondrial apoptotic pathways are involved. This study represents the first steps towards understanding the mode of action of this promising class of new osmium-based chemotherapeutics.

  10. Polyyn-diyls capped by diruthenium termini: a new family of carbon-rich organometallic compounds and distance-dependent electronic coupling therein.

    PubMed

    Xu, Guo-Lin; Zou, Gang; Ni, Yu-Hua; DeRosa, Maria C; Crutchley, Robert J; Ren, Tong

    2003-08-20

    Polyyn-diyls capped by Ru(2)(ap)(4) termini (ap = 2-anilinopyridinate), that is, [Ru2(ap)4](mu-C,C'-C2m)[Ru2(ap)4] (compounds 1-5 with m = 1-4 and 6), were synthesized through either a metathesis reaction between Ru2(ap)4Cl and LiC(2m)Li or a Glaser homocoupling reaction of Ru2(ap)4(CmH) under Eglinton/Hay conditions. X-ray diffraction studies of compounds 2 and 4 revealed both the linear rigid rod topology of these compounds and the fine structural details about the Ru2 cores and polyyn-diyl chains. Cyclic and differential pulse voltammetric (CV and DPV) measurements and spectroelectrochemical studies show that reduced and oxidized forms of 1, 2, 4, and 5 are donor-acceptor systems in which the Ru2 termini are coupled to varying degrees depending upon the length of the polyyn-diyl bridge.

  11. Structure investigations of group 13 organometallic carboxylates.

    PubMed

    Justyniak, Iwona; Prochowicz, Daniel; Tulewicz, Adam; Bury, Wojciech; Goś, Piotr; Lewiński, Janusz

    2017-01-17

    The octet-compliant group 13 organometallics with highly polarized bonds in the metal coordination sphere exhibit a significant tendency to maximize their coordination number through the formation of adducts with a wide range of neutral donor ligands or by self-association to give aggregates containing tetrahedral and higher coordinated aluminium centres, and even in some cases molecular complexes equilibrate with ionic species of different coordination numbers of the metal centre. This work provides a comprehensive overview of the structural chemistry landscape of the group 13 carboxylates. Aside from a more systematic approach to the general structural chemistry of the title compounds, the structure investigations of [R2M(μ-O2CPh)]2-type benzoate complexes (where M = B, Al and Ga) and their Lewis acid-base adducts [(R2M)(μ-O2CPh)(py-Me)] are reported. DFT calculations were also performed to obtain a more in-depth understanding of both the changes in the bonding of group 13 organometallic carboxylate adducts with a pyridine ligand.

  12. Perfluorinated Ligands in Organometallic Chemistry

    DTIC Science & Technology

    1989-12-12

    Decacarbonyldimanganese. Organometallics, 1986, 1,2391. W.P. Henry and R.P. Hughes, Organic Synthesis Using Carbon Monoxide. Regiospecific Cobalt Mediated...Pentamethylcyclopentadiene with Decacarbonyldi manganese. Organometalllcs, 1986, 1,2391. 4. W.P. Henry and R.P. Hughes, Organic Synthesis Using Carbon

  13. Organometallic-inorganic hybrid electrodes for lithium-ion batteries

    DOEpatents

    Huang, Qian; Lemmon, John P.; Choi, Daiwon; Cosimbescu, Lelia

    2016-09-13

    Disclosed are embodiments of active materials for organometallic and organometallic-inorganic hybrid electrodes and particularly active materials for organometallic and organometallic-inorganic hybrid cathodes for lithium-ion batteries. In certain embodiments the organometallic material comprises a ferrocene polymer.

  14. NEW APPLICATIONS OF LC-MS AND LC-MS2 TOWARD UNDERSTANDING THE ENVIRONMENTAL FATE OF ORGANOMETALLICS

    EPA Science Inventory

    Over the last 40 years, many organometallic compounds have been synthesized and used in a variety of consumer, agricultural, and industrial products. Including wastewater effluents, leaching, and direct land and water applications, there are many pathways that can disperse organo...

  15. Use of ionic liquids as coordination ligands for organometallic catalysts

    DOEpatents

    Li, Zaiwei; Tang, Yongchun; Cheng; Jihong

    2009-11-10

    Aspects of the present invention relate to compositions and methods for the use of ionic liquids with dissolved metal compounds as catalysts for a variety of chemical reactions. Ionic liquids are salts that generally are liquids at room temperature, and are capable of dissolving a many types of compounds that are relatively insoluble in aqueous or organic solvent systems. Specifically, ionic liquids may dissolve metal compounds to produce homogeneous and heterogeneous organometallic catalysts. One industrially-important chemical reaction that may be catalyzed by metal-containing ionic liquid catalysts is the conversion of methane to methanol.

  16. Organometallic Chemistry and Catalysis in Industry.

    ERIC Educational Resources Information Center

    Parshall, George W.; Putscher, Richard E.

    1986-01-01

    Traces the growth in the industrial usage of organometallic chemistry from 1950 to 1977, pointing out that this growth involved the production of commodity chemicals. Indicates that one of the early successes of organometallic chemistry was the discovery of ethylene polymerization catalysts. (JN)

  17. Conjugated organometallic materials containing tungsten centers

    NASA Astrophysics Data System (ADS)

    Jones, Marya

    Our group is interested in the optical and electronic properties of organometallic analogues of conjugated organic compounds. Specifically, in this thesis we will discuss the properties of complexes in which W≡C moieties replace C≡C fragments within the framework of oligo(phenyleneethynylenes) and a C4-polyyne. A family of derivatives of the type Ph(C≡CC6H4 )m(L)4W≡C(C6H 4C≡C)nPh (m = 0, 1; n = 0, 1, 2) have been prepared and characterized by X-ray crystallography, electronic-absorption spectroscopy, and electrochemistry. This substitution has allowed us to directly compare the electronic and optical properties of these organometallic complexes with those of their organic analogues. We found that while these systems exhibit redox and spectroscopic properties similar to those of their organic counterparts they also exhibit new characteristics that are due to the incorporation of the metal center. The design of these compounds has also allowed us to address how the position of the metal within the backbone affects the electronic and optical properties of these compounds. We found that the position of the metal is important in controlling the electronic structure of the material, thus suggesting that the properties of these compounds can be further tuned by changing the position of the metal within the conjugated carbon chain. In addition, we have appended sulfur and isocyanide functionalities to oligo(phenyleneethynylene) analogues. A family of compounds of the type Cl(dppe) 2W(≡CC6H4-4-(C≡CC6H 4)m-4'-R) (m = l, 2; R = N≡C, SCH2CH 2Si(CH3)3) have been prepared and characterized by electronic-absorption spectroscopy and electrochemistry. Differences between the sulfur and isocyanide functionalities are examined, along with the effects of extending conjugation along the arylidyne chain. Evidence that the sulfur-containing arylidyne complexes form self-assembled monolayers on Au and Pt electrodes is presented. In addition, the electron-transfer rates for

  18. An organometallic guide to the chemistry of hydrocarbon moieties on transition metal surfaces

    SciTech Connect

    Zaera, F.

    1995-12-01

    In this review what is known about the chemistry of hydrocarbon molecules on transition metal surfaces will be surveyed. Here the authors discuss the results reported to date on the structure and reactivity of the different types of hydrocarbon moieties that form on transition metal surfaces. One of the goals of this review is to provide an organometallic guide for the possible interactions of hydrocarbons with transition metals with the idea of examining their relation to the corresponding surface chemistry. The authors however limit the review of the organometallic literature to the information relevant to the surface systems, and also narrow the field to cover only molecules with carbon and hydrogen atoms; compounds containing other atoms (O, S, N) will be excluded. The present review is organized in the following manner. First, a brief discussion of the experimental techniques used to characterize both organometallic and surface systems is presented. A discussion of the coordination and structure of the different types of organic moieties, first in organometallic compounds and then on metal surfaces, follows. Here the systems are classified according to the type of bonding between the molecules and the metals. Next, the different elementary steps that such systems can undergo are summarized: C-H and C-C bond-breaking and bond-forming reactions, isomerizations, and others. Again, the chemistry of organometallic compounds is discussed first, and the surface chemistry is presented subsequently. A brief description of a few key nonelementary reactions is also given, including some catalytic processes. Lastly, a brief discussion on the main similarities and differences found so far between surface and organometallic systems, and on possible future directions for this field, is offered.

  19. Anticancer Organometallic Osmium(II)-p-cymene Complexes.

    PubMed

    Păunescu, Emilia; Nowak-Sliwinska, Patrycja; Clavel, Catherine M; Scopelliti, Rosario; Griffioen, Arjan W; Dyson, Paul J

    2015-09-01

    Osmium compounds are attracting increasing attention as potential anticancer drugs. In this context, a series of bifunctional organometallic osmium(II)-p-cymene complexes functionalized with alkyl or perfluoroalkyl groups were prepared and screened for their antiproliferative activity. Three compounds from the series display selectivity toward cancer cells, with moderate cytotoxicity observed against human ovarian carcinoma (A2780) cells, whereas no cytotoxicity was observed on non-cancerous human embryonic kidney (HEK-293) cells and human endothelial (ECRF24) cells. Two of these three cancer-cell-selective compounds induce cell death largely via apoptosis and were also found to disrupt vascularization in the chicken embryo chorioallantoic membrane (CAM) model. Based on these promising properties, these compounds have potential clinical applications.

  20. Sizable band gap in organometallic topological insulator

    NASA Astrophysics Data System (ADS)

    Derakhshan, V.; Ketabi, S. A.

    2017-01-01

    Based on first principle calculation when Ceperley-Alder and Perdew-Burke-Ernzerh type exchange-correlation energy functional were adopted to LSDA and GGA calculation, electronic properties of organometallic honeycomb lattice as a two-dimensional topological insulator was calculated. In the presence of spin-orbit interaction bulk band gap of organometallic lattice with heavy metals such as Au, Hg, Pt and Tl atoms were investigated. Our results show that the organometallic topological insulator which is made of Mercury atom shows the wide bulk band gap of about ∼120 meV. Moreover, by fitting the conduction and valence bands to the band-structure which are produced by Density Functional Theory, spin-orbit interaction parameters were extracted. Based on calculated parameters, gapless edge states within bulk insulating gap are indeed found for finite width strip of two-dimensional organometallic topological insulators.

  1. Organometallic chemistry meets crystal engineering to give responsive crystalline materials.

    PubMed

    Bacchi, A; Pelagatti, P

    2016-01-25

    Dynamically porous crystalline materials have been obtained by engineering organometallic molecules. This feature article deals with organometallic wheel-and-axle compounds, molecules with two relatively bulky groups (wheels) connected by a linear spacer. The wheels are represented by half-sandwich Ru(ii) moieties, while the spacer can be covalent or supramolecular in character. Covalent spacers are obtained using divergent bidentate ligands connecting two [(arene)RuX2] groups. Supramolecular spacers are instead obtained by exploiting the dimerization of COOH or C(O)NH2 groups appended to N-based ligands. A careful choice of ligand functional groups and X ligands leads to the isolation of crystalline materials with remarkable host-guest properties, evidenced by the possibility of reversibly capturing/releasing volatile guests through heterogenous solid-gas reactions. Structural correlations between the crystalline arrangement of the apohost and the host-guest compounds allow us to envisage the structural path followed by the system during the exchange processes.

  2. Combinatorial sythesis of organometallic materials

    DOEpatents

    Schultz, Peter G.; Xiang, Xiaodong; Goldwasser, Isy

    2002-07-16

    Methods and apparatus for the preparation and use of a substrate having an array of diverse materials in predefined regions thereon. A substrate having an array of diverse materials thereon is generally prepared by delivering components of materials to predefined regions on a substrate, and simultaneously reacting the components to form at least two materials. Materials which can be prepared using the methods and apparatus of the present invention include, for example, covalent network solids, ionic solids and molecular solids. More particularly, materials which can be prepared using the methods and apparatus of the present invention include, for example, inorganic materials, intermetallic materials, metal alloys, ceramic materials, organic materials, organometallic materials, non-biological organic polymers, composite materials (e.g., inorganic composites, organic composites, or combinations thereof), etc. Once prepared, these materials can be screened for useful properties including, for example, electrical, thermal, mechanical, morphological, optical, magnetic, chemical, or other properties. Thus, the present invention provides methods for the parallel synthesis and analysis of novel materials having useful properties.

  3. Patterns in Organometallic Chemistry with Application in Organic Synthesis.

    ERIC Educational Resources Information Center

    Schwartz, Jeffrey; Labinger, Jay A.

    1980-01-01

    Of interest in this discussion of organometallic complexes are stoichiometric or catalytic reagents for organic synthesis in the complex transformations observed during synthesis for transition metal organometallic complexes. Detailed are general reaction types from which the chemistry or many transition metal organometallic complexes can be…

  4. Hydrotreatment of bio-oil over Ni-based catalyst.

    PubMed

    Zhang, Xinghua; Wang, Tiejun; Ma, Longlong; Zhang, Qi; Jiang, Ting

    2013-01-01

    Inexpensive non-sulfided Ni-based catalysts were evaluated for hydrotreatments using phenol as model compound. HZSM-5, a zeolite with different ratio of Si/Al and γ-Al(2)O(3) were impregnated with Ni(NO(3))(2) · 6H(2)O and calcined at 450 °C. Conversion rates and product distribution for treatment of phenol at 160-240 °C in the presence of catalysts with nickel loads of 6, 10, 14 and 17 wt.% were determined. Phenol conversion was highest (91.8%) at 240 °C in the presence of HZSM-5(Si/Al = 38) loaded with 10% Ni. When hydrotreatment was carried out with bio-oil obtained from pyrolysis of pine sawdust under the optimal conditions determined for phenol, the pH of bio-oil increased from 2.27 to 4.07, and the hydrogen content increased from 6.28 to 7.01 wt.%. The decrease in acidity is desirable for the use of upgraded bio-oil.

  5. Organometallic Antitumour Agents with Alternative Modes of Action

    NASA Astrophysics Data System (ADS)

    Casini, Angela; Hartinger, Christian G.; Nazarov, Alexey A.; Dyson, Paul J.

    The therapeutic index of drugs that target DNA, a ubiquitous target present in nearly all cells, is low. Nevertheless, DNA has remained the primary target for medicinal chemists developing metal-based anticancer drugs, although DNA has been essentially abandoned in favour of non-genomic targets by medicinal chemists developing organic drugs. A number of organometallic drugs that target proteins/enzymes have been developed and these compounds, based on ruthenium, osmium and gold, are described in this chapter. Targets include cathepsin B, thioredoxin reductases, multidrug resistance protein (Pgp), glutathione S-transferases and kinases. It is found that compounds that inhibit these various targets are active against metastatic tumours, or tumours that are resistant to classical DNA damaging agents such as cisplatin, and therefore offer considerable potential in clinical applications.

  6. Cytotoxic properties of a new organometallic platinum(II) complex and its gold(I) heterobimetallic derivatives.

    PubMed

    Serratrice, Maria; Maiore, Laura; Zucca, Antonio; Stoccoro, Sergio; Landini, Ida; Mini, Enrico; Massai, Lara; Ferraro, Giarita; Merlino, Antonello; Messori, Luigi; Cinellu, Maria Agostina

    2016-01-14

    A novel platinum(ii) organometallic complex, [Pt(pbi)(Me)(DMSO)], bearing the 2-(2'-pyridyl)-benzimidazole (pbiH) ligand, was synthesized and fully characterized. Interestingly, the reaction of this organometallic platinum(ii) complex with two distinct gold(i) phosphane compounds afforded the corresponding heterobimetallic derivatives with the pbi ligand bridging the two metal centers. The antiproliferative properties in vitro of [Pt(pbi)(Me)(DMSO)] and its gold(i) derivatives as well as those of the known coordination platinum(ii) and palladium(ii) complexes with the same ligand, of the general formula [MCl2(pbiH)], were comparatively evaluated against A2780 cancer cells, either sensitive or resistant to cisplatin. A superior biological activity of the organometallic compound clearly emerged compared to the corresponding platinum(ii) complex; the antiproliferative effects are further enhanced upon attaching the gold(i) triphenylphosphine moiety to the organometallic Pt compound. Remarkably, these novel metal species are able to overcome nearly complete resistance to cisplatin. Significant mechanistic insight into the study compounds was gained after investigating their reactions with a few representative biomolecules by electrospray mass spectrometry and X-ray crystallography. The obtained results are comprehensively discussed.

  7. Pulsed Laser Deposition of the Ni-Base Superalloy Films

    NASA Astrophysics Data System (ADS)

    Shin, Joonghan; Mazumder, Jyotirmoy

    2016-03-01

    Ni-base superalloy films were deposited on single-crystal (SC) Ni-base superalloy substrates from a target with the same alloy composition by pulsed laser deposition (PLD) technique. Microstructure and growth behavior of the films deposited were investigated by X-ray diffraction and scanning electron microscopy, and atomic force microscope. The homoepitaxial growth of the SC Ni-base superalloy film occurred at the 1123 K (850 °C) substrate temperature and 2 J/cm2 pulse energy. Films generally exhibited a strong polycrystalline characteristic as the substrate temperature and pulse energy increased. The SC film had a smooth surface. The measured root mean square roughness of the SC film surface was ~6 nm. Based on the Taguchi analysis, the substrate temperature and pulse energy were the most significant process parameters influencing the structural characteristics of the films. Also, the influence of the pulse repletion rate and deposition time was not found to be significant.

  8. A ferroelectric olefin-copper(I) organometallic polymer with flexible organic ligand (R)-MbVBP

    NASA Astrophysics Data System (ADS)

    Wang, Guo-Xi; Xing, Zheng; Chen, Li-Zhuang; Han, Guang-Fan

    2015-07-01

    Hydrothermal treatment of (R)-2-methyl-1,4-bis(4-vinylbenzyl)piperazine [(R)-MbVBP] and CuCl afforded a novel olefin-copper(I) coordination compound. Introducing the flexible ligand (R)-MbVBP allowed the olefin-copper(I) organometallic compound to crystallize in a polar point group P21. The compound was ferroelectric, and its electric hysteresis loop showed a remnant polarization (Pr) of 0.13-0.32 μC cm-2 and a coercive field (Ec) of 3.5-11 kV cm-1.

  9. Mechanistic study of organometallic vapor phase epitaxy

    SciTech Connect

    Stringfellow, G.B.

    1990-12-31

    Only AsH{sub 3} and PH{sub 3} have been used as the group V source molecules for organometallic vapor phase epitaxy (OMVPE) of III/V semiconductors until recently, since they have been the only precursors yielding device quality materials. This paper reviews recent work on the pyrolysis of individual organometallic molecules, with emphasis on the group V sources, including: (1) the methylarsines, di- and tri-methylarsine, (2) the ethylarsines, mono-, di-, and tri-ethylarsine, and (3) the singly substituted tertiarybutyl arsine and phosphine molecules. The pyrolysis and growth reactions occurring when both group III and group V precursors are present simultaneously, i.e., the reactions occuring during OMVPE growth of several III/V semiconductors, are also briefly reviewed.

  10. Mechanistic study of organometallic vapor phase epitaxy

    SciTech Connect

    Stringfellow, G.B.

    1990-01-01

    Only AsH{sub 3} and PH{sub 3} have been used as the group V source molecules for organometallic vapor phase epitaxy (OMVPE) of III/V semiconductors until recently, since they have been the only precursors yielding device quality materials. This paper reviews recent work on the pyrolysis of individual organometallic molecules, with emphasis on the group V sources, including: (1) the methylarsines, di- and tri-methylarsine, (2) the ethylarsines, mono-, di-, and tri-ethylarsine, and (3) the singly substituted tertiarybutyl arsine and phosphine molecules. The pyrolysis and growth reactions occurring when both group III and group V precursors are present simultaneously, i.e., the reactions occuring during OMVPE growth of several III/V semiconductors, are also briefly reviewed.

  11. Preparation of uranium compounds

    DOEpatents

    Kiplinger, Jaqueline L; Montreal, Marisa J; Thomson, Robert K; Cantat, Thibault; Travia, Nicholas E

    2013-02-19

    UI.sub.3(1,4-dioxane).sub.1.5 and UI.sub.4(1,4-dioxane).sub.2, were synthesized in high yield by reacting turnings of elemental uranium with iodine dissolved in 1,4-dioxane under mild conditions. These molecular compounds of uranium are thermally stable and excellent precursor materials for synthesizing other molecular compounds of uranium including alkoxide, amide, organometallic, and halide compounds.

  12. Molecular alloys, linking organometallics with intermetallic Hume-Rothery phases: the highly coordinated transition metal compounds [M(ZnR)(n)] (n >or= 8) containing organo-zinc ligands.

    PubMed

    Cadenbach, Thomas; Bollermann, Timo; Gemel, Christian; Tombul, Mustafa; Fernandez, Israel; von Hopffgarten, Moritz; Frenking, Gernot; Fischer, Roland A

    2009-11-11

    This paper presents the preparation, characterization and bonding analyses of the closed shell 18 electron compounds [M(ZnR)(n)] (M = Mo, Ru, Rh, Ni, Pd, Pt, n = 8-12), which feature covalent bonds between n one-electron organo-zinc ligands ZnR (R = Me, Et, eta(5)-C(5)(CH(3))(5) = Cp*) and the central metal M. The compounds were obtained in high isolated yields (>80%) by treatment of appropriate GaCp* containing transition metal precursors 13-18, namely [Mo(GaCp*)(6)], [Ru(2)(Ga)(GaCp*)(7)(H)(3)] or [Ru(GaCp*)(6)(Cl)(2)], [(Cp*Ga)(4)RhGa(eta(1)-Cp*)Me] and [M(GaCp*)(4)] (M = Ni, Pd, Pt) with ZnMe(2) or ZnEt(2) in toluene solution at elevated temperatures of 80-110 degrees C within a few hours of reaction time. Analytical characterization was done by elemental analyses (C, H, Zn, Ga), (1)H and (13)C NMR spectroscopy. The molecular structures were determined by single crystal X-ray diffraction. The coordination environment of the central metal M and the M-Zn and Zn-Zn distances mimic the situation in known solid state M/Zn Hume-Rothery phases. DFT calculations at the RI-BP86/def2-TZVPP and BP86/TZ2P+ levels of theory, AIM and EDA analyses were done with [M(ZnH)(n)] (M = Mo, Ru, Rh, Pd; n = 12, 10, 9, 8) as models of the homologous series. The results reveal that the molecules can be compared to 18 electron gold clusters of the type M@Au(n), that is, W@Au(12), but are neither genuine coordination compounds nor interstitial cage clusters. The molecules are held together by strong radial M-Zn bonds. The tangential Zn-Zn interactions are generally very weak and the (ZnH)(n) cages are not stable without the central metal M.

  13. The water soluble ruthenium(II) organometallic compound [Ru(p-cymene)(bis(3,5 dimethylpyrazol-1-yl)methane)Cl]Cl suppresses triple negative breast cancer growth by inhibiting tumor infiltration of regulatory T cells.

    PubMed

    Montani, Maura; Pazmay, Gretta V Badillo; Hysi, Albana; Lupidi, Giulio; Pettinari, Riccardo; Gambini, Valentina; Tilio, Martina; Marchetti, Fabio; Pettinari, Claudio; Ferraro, Stefano; Iezzi, Manuela; Marchini, Cristina; Amici, Augusto

    2016-05-01

    Ruthenium compounds have become promising alternatives to platinum drugs by displaying specific activities against different cancers and favorable toxicity and clearance properties. Here, we show that the ruthenium(II) complex [Ru(p-cymene)(bis(3,5-dimethylpyrazol-1-yl)methane)Cl]Cl (UNICAM-1) exhibits potent in vivo antitumor effects. When administered as four-dose course, by repeating a single dose (52.4mgkg-1) every three days, UNICAM-1 significantly reduces the growth of A17 triple negative breast cancer cells transplanted into FVB syngeneic mice. Pharmacokinetic studies indicate that UNICAM-1 is rapidly eliminated from kidney, liver and bloodstream thanks to its high hydrosolubility, exerting excellent therapeutic activity with minimal side effects. Immunohistological analysis revealed that the efficacy of UNICAM-1, mainly relies on its capacity to reverse tumor-associated immune suppression by significantly reducing the number of tumor-infiltrating regulatory T cells. Therefore, UNICAM-1 appears very promising for the treatment of TNBC.

  14. In vitro antimalarial activity of a new organometallic analog, ferrocene-chloroquine.

    PubMed

    Domarle, O; Blampain, G; Agnaniet, H; Nzadiyabi, T; Lebibi, J; Brocard, J; Maciejewski, L; Biot, C; Georges, A J; Millet, P

    1998-03-01

    The in vitro activities of new organometallic chloroquine analogs, based on 4-amino-quinoleine compounds bound to a molecule of ferrocene, were evaluated against chloroquine-susceptible, chloroquine-intermediate, and chloroquine-resistant, culture-adapted Plasmodium falciparum lineages by a proliferation test. One of the ferrocene analogs totally restored the activity of chloroquine against chloroquine-resistant parasites. This compound, associated with tartaric acid for better solubility, was highly effective. The role of the ferrocene in reversing chloroquine resistance is discussed, as is its potential use for human therapy.

  15. In Vitro Antimalarial Activity of a New Organometallic Analog, Ferrocene-Chloroquine

    PubMed Central

    Domarle, O.; Blampain, G.; Agnaniet, H.; Nzadiyabi, T.; Lebibi, J.; Brocard, J.; Maciejewski, L.; Biot, C.; Georges, A. J.; Millet, P.

    1998-01-01

    The in vitro activities of new organometallic chloroquine analogs, based on 4-amino-quinoleine compounds bound to a molecule of ferrocene, were evaluated against chloroquine-susceptible, chloroquine-intermediate, and chloroquine-resistant, culture-adapted Plasmodium falciparum lineages by a proliferation test. One of the ferrocene analogs totally restored the activity of chloroquine against chloroquine-resistant parasites. This compound, associated with tartaric acid for better solubility, was highly effective. The role of the ferrocene in reversing chloroquine resistance is discussed, as is its potential use for human therapy. PMID:9517929

  16. Organotitanoxanes with unique structure among transition-element organometallic oxide derivatives.

    PubMed

    Buitrago, Olga; Mosquera, Marta E G; Jiménez, Gerardo; Cuenca, Tomás

    2008-05-19

    The synthesis of novel titanoxane compounds, [{(TiCl)(Ti)[mu-(eta(5)-C5Me4SiMe2O-kappaO)]2(mu-O)}2(mu-O)] (4) and [{Ti[mu-(eta(5)-C5Me4SiMe2O-kappaO)](mu-O)}6] (5), by controlled hydrolysis of a dinuclear titanium/oxo complex is described. Complexes 4 and 5 show unprecedented structural features for organometallic oxide derivatives of transition elements and represent unique fully characterized examples of tetra- and hexanuclear organo-transition-metal oxide compounds with an open-chain and a monocyclic structure, respectively.

  17. Transuranic organometallics: The next generation

    SciTech Connect

    Zwick, B.D.; Sattelberger, A.P.; Avens, L.R.

    1990-01-01

    Neptunium and plutonium metal react cleanly with 3/2 equiv. I{sub 2} in aprotic ligating solvents, L, such as tetrahydrofuran (THF), pyridine (Py), and dimethylsulfoxide (DMSO) to give the triiodide complexes as tetrasolvates, AnI{sub 3}(L){sub 4} (An = Np, L = THF (1)); An = Pu, L = THF (2a), Py (2b), and DMSO (2c). These triiodide complexes are convenient precursors to new transuranic compounds. Reaction of the triiodide complexes 1 and 2a hexane with 3 equiv. of sodium bis(trimethylsilyl)amide give the volatile, solvate-free tris(silylamide) complexes, An(N(SiMe{sub 3}){sub 2}){sub 3} (An = Np, 3; An = Pu, 4). The silylamide complexes 3 and 4 undergo rapid reaction in hexane upon stoichiometric addition of HO-2,6-(t-C{sub 4}H{sub 9}){sub 2}C{sub 6}H{sub 3} to give the aryl oxide complexes An(O-2,6-(t-C{sub 4}H{sub 9}){sub 2}C{sub 6}H{sub 3}){sub 3} (An = Np, 5; An = Pu, 6). Preliminary investigations suggest that the aryl oxide complexes 5 and 6 react with lithium bis(trimethylsilyl)methanide, Li{sup +} CH(SiMe{sub 3}){sub 2}, in hexane to give the homoleptic alkyl complexes An(CH(SiMe{sub 3}){sub 2}){sub 3} (An = Np, 7; An = Pu, 8). The homoleptic silylamide, aryl oxide, and alkyl complexes are the first to be reported for transuranic elements. 17 refs.

  18. In Situ Observation of Active Oxygen Species in Fe-Containing Ni-Based Oxygen Evolution Catalysts: The Effect of pH on Electrochemical Activity.

    PubMed

    Trześniewski, Bartek J; Diaz-Morales, Oscar; Vermaas, David A; Longo, Alessandro; Bras, Wim; Koper, Marc T M; Smith, Wilson A

    2015-12-09

    Ni-based oxygen evolution catalysts (OECs) are cost-effective and very active materials that can be potentially used for efficient solar-to-fuel conversion process toward sustainable energy generation. We present a systematic spectroelectrochemical characterization of two Fe-containing Ni-based OECs, namely nickel borate (Ni(Fe)-B(i)) and nickel oxyhydroxide (Ni(Fe)OOH). Our Raman and X-ray absorption spectroscopy results show that both OECs are chemically similar, and that the borate anions do not play an apparent role in the catalytic process at pH 13. Furthermore, we show spectroscopic evidence for the generation of negatively charged sites in both OECs (NiOO(-)), which can be described as adsorbed "active oxygen". Our data conclusively links the OER activity of the Ni-based OECs with the generation of those sites on the surface of the OECs. The OER activity of both OECs is strongly pH dependent, which can be attributed to a deprotonation process of the Ni-based OECs, leading to the formation of the negatively charged surface sites that act as OER precursors. This work emphasizes the relevance of the electrolyte effect to obtain catalytically active phases in Ni-based OECs, in addition to the key role of the Fe impurities. This effect should be carefully considered in the development of Ni-based compounds meant to catalyze the OER at moderate pHs. Complementarily, UV-vis spectroscopy measurements show strong darkening of those catalysts in the catalytically active state. This coloration effect is directly related to the oxidation of nickel and can be an important factor limiting the efficiency of solar-driven devices utilizing Ni-based OECs.

  19. Zirconocene and Si-tethered diynes: a happy match directed toward organometallic chemistry and organic synthesis.

    PubMed

    Zhang, Wen-Xiong; Zhang, Shaoguang; Xi, Zhenfeng

    2011-07-19

    Characterizing reactive organometallic intermediates is critical for understanding the mechanistic aspects of metal-mediated organic reactions. Moreover, the isolation of reactive organometallic intermediates can often result in the ability to design new synthetic methods. In this Account, we outline synthetic methods that we developed for a variety of diverse Zr/Si organo-bimetallic compounds and Si/N heteroatom-organic compounds through the detailed study of zirconacyclobutene-silacyclobutene fused compounds. Two basic components are involved in this chemistry. The first is the Si-tethered diyne, which owes its rich reactive palette to the combination of the Si-C bond and the C≡C triple bond. The second is the low-valent zirconocene species Cp(2)Zr(II), which has proven very useful in organic synthesis. The reaction of these two components affords the zirconacyclobutene-silacyclobutene fused compound, which is the key reactive Zr/Si organo-bimetallic intermediate discussed here. We discuss the three types of reactions that have been developed for the zirconacyclobutene-silacyclobutene fused intermediate. The reaction with nitriles (the C≡N triple bond) is introduced in the first section. In this one-pot reaction, up to four different components can be combined: the Si-tethered diyne can be reacted with three identical nitriles, with differing nitriles, or with a nitrile and other unsaturated organic substrates such as formamides, isocyanides, acid chlorides, aldehydes, carbodiimides, and azides. Several unexpected multiring, fused Zr/Si organo-bimetallic intermediates were isolated and characterized. A wide variety of N-heterocycles, such as 5-azaindole, pyrrole, and pyrroloazepine derivatives, were obtained. We then discuss the reaction with alkynes (the C≡C triple bond). A consecutive skeletal rearrangement, differing from that observed in the reactions with nitriles, takes place in this reaction. Finally, we discuss the reaction with the C═X substrates

  20. Sample treatment in chromatography-based speciation of organometallic pollutants.

    PubMed

    Gómez-Riza, J L; Morales, E; Giráldez, I; Sánchez-Rodas, D; Velasco, A

    2001-12-14

    Speciation analysis is nowadays performed routinely in many laboratories to control the quality of the environment, food and health. Chemical speciation analyses generally include the study of different oxidation state of elements or individual organometallic compounds. The determination of the different chemical forms of elements is still an analytical challenge, since they are often unstable and concentrations in different matrices of interest are in the microg l(-1) or even in the ng l(-1) range (e.g., estuarine waters) or ng g(-1) in sediments and biological tissues. For this reason, sensitive and selective analytical atomic techniques are being used as available detectors for speciation, generally coupled with chromatography for the time-resolved introduction of analytes into the atomic spectrometer. The complexity of these instrumental couplings has a straightforward consequence on the duration of the analysis, but sample preparation to separate and transfer the chemical species present in the sample into a solution to be accepted readily by a chromatographic column is the more critical step of total analysis, and demands considerable operator skills and time cost. Traditionally, liquid-liquid extraction has been employed for sample treatment with serious disadvantages, such as consumption, disposal and long-term exposure to organic solvent. In addition, they are usually cumbersome and time-consuming. Therefore, the introduction of new reagents such as sodium tetraethylborate for the simultaneous derivatization of several elements has been proposed. Other possibilities are based in the implementation of techniques for efficient and accelerated isolation of species from the sample matrix. This is the case for microwave-assisted extraction, solid-phase extraction and microextraction, supercritical fluid extraction or pressurized liquid extraction, which offer new possibilities in species treatment, and the advantages of a drastic reduction of the extraction

  1. Organometallic Bonding in an Ullmann-Type On-Surface Chemical Reaction Studied by High-Resolution Atomic Force Microscopy.

    PubMed

    Kawai, Shigeki; Sadeghi, Ali; Okamoto, Toshihiro; Mitsui, Chikahiko; Pawlak, Rémy; Meier, Tobias; Takeya, Jun; Goedecker, Stefan; Meyer, Ernst

    2016-10-01

    The on-surface Ullmann-type chemical reaction synthesizes polymers by linking carbons of adjacent molecules on solid surfaces. Although an organometallic compound is recently identified as the reaction intermediate, little is known about the detailed structure of the bonded organometallic species and its influence on the molecule and the reaction. Herein atomic force microscopy at low temperature is used to study the reaction with 3,9-diiododinaphtho[2,3-b:2',3'-d]thiophene (I-DNT-VW), which is polymerized on Ag(111) in vacuum. Thermally sublimated I-DNT-VW picks up a Ag surface atom, forming a CAg bond at one end after removing an iodine. The CAg bond is usually short-lived, and a CAgC organometallic bond immediately forms with an adjacent molecule. The existence of the bonded Ag atoms strongly affects the bending angle and adsorption height of the molecular unit. Density functional theory calculations reveal the bending mechanism, which reveals that charge from the terminus of the molecule is transferred via the Ag atom into the organometallic bond and strengths the local adsorption to the substrate. Such deformations vanish when the Ag atoms are removed by annealing and CC bonds are established.

  2. [Mechanistic examination of organometallic electron transfer reactions: Annual report, 1989

    SciTech Connect

    Not Available

    1989-12-31

    Our mechanistic examination of electron transfer reactions between organometallic complexes has required data from our stopped-flow infrared spectrophotometer that was constructed in the first year. Our research on organometallic electron transfer reaction mechanisms was recognized by an invitation to the Symposium on Organometallic Reaction Mechanisms at the National ACS meeting in Miami. We have obtained a reasonable understanding of the electron transfer reactions between metal cations and anions and between metal carbonyl anions and metal carbonyl dimers. In addition we have begun to obtain data on the outer sphere electron transfer between metal carbonyl anions and coordination complexes and on reactions involving cluster anions.

  3. UV excimer laser photochemistry of hybrid organometallic compounds of gallium

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Cleaver, W. M.; Stuke, M.; Barron, A. R.

    1992-09-01

    The gas phase ultraviolet (UV) excimer laser induced photolysis of the gallium-alkyls Ga( t-C4H9) n - (CH3)3- n ( n=0, 1, 2, 3) was studied, using photolysis wavelengths of 308, 248, and 193 nm. The photofragments Ga, GaH, and GaCH3 were detected by laser ionization time-of-flight mass spectroscopy, while the hydrocarbon products CH4, C2H6, HC(CH3)3 and H2C=C(CH3)2 were identified using Fourier transform infrared (FTIR) spectroscopy. The formation of the GaH photofragment, and a high olefin-to-alkane product ratio, for Ga( t-C4H9)2(CH3) and Ga( t-C4H9)3 are interpreted to indicate a β-hydrogen elimination process. However, β-hydrogen elimination only occurs after fission of the weakest Ga-C bond, thus no β-hydride elimination is observed for Ga( t-C4H9)(CH3)2. Detection of C2H6 for Ga(CH3)3 and Ga( t-C4H9)(CH3)2, but not for Ga( t-C4H9)2(CH3), shows that under our experimental conditions the formation of ethane is as a result of the reductive elimination of the methyl groups, and is not due to the recombination of two free methyl radicals.

  4. Strain induced directional coarsening in Ni based superalloys

    SciTech Connect

    Veron, M.; Brechet, Y.; Louchet, F.

    1996-06-15

    Directional coarsening (or rafting) in Ni-based single crystal superalloys occurs after short times under stress at high temperature. This phenomenon results in a strongly anisotropic evolution of the microstructure that needs to be understood since it can occur in superalloy turbine blades during service. As the strain induced during creep seems to be responsible for the rafting phenomenon, it is worth studying the effect of a strain gradient on coarsened structures. A simple way to do this is to investigate the coarsening morphologies developed around an indentation.

  5. Determining the Quantum Efficiency for Activation of an Organometallic Photoinitiator for Cationic Polymerization: An Experiment for the Physical or Inorganic Chemistry Laboratory

    ERIC Educational Resources Information Center

    Hayes, David M.; Mahar, Maura; Schnabel, R. Chris; Shah, Paras; Lees, Alistair J.; Jakubek, Vladimir

    2007-01-01

    We present a new laboratory experiment on the photochemistry of organometallic [eta][superscript 5],[eta][superscript 6]-mixed-sandwich compounds, which is suitable for both the physical chemistry and inorganic chemistry laboratory. Specifically, students use 1,10-phenanthroline to trap the intermediate formed when…

  6. High-sensitivity molecular organometallic resist for EUV (MORE)

    NASA Astrophysics Data System (ADS)

    Passarelli, James; Murphy, Michael; Del Re, Ryan; Sortland, Miriam; Dousharm, Levi; Vockenhuber, Michaela; Ekinci, Yasin; Neisser, Mark; Freedman, Daniel A.; Brainard, Robert L.

    2015-03-01

    We have developed organometallic carboxylate compounds [RnM(O2CR')2] capable of acting as negativetone EUV resists. Overall, the best and fastest resists contain antimony, are pentavalent and the carboxylate group contains a polymerizable olefin (e.g. acrylate, methacrylate or styrenecarboxylate). Evidence suggests that high sensitivity is achieved through the polymerization of olefins in the exposed region. We have performed a systematic sensitivity study of molecules of the type RnM(O2CR')2 where we have studied seven R groups, four main group metals (M), and three polymerizable carboxylate groups (O2CR'). We found that the greatest predictor of sensitivity of the RnSb(O2CR')2 resists is their level of polymerizable olefins. We mathematically define the polymerizable olefin loading (POL) as the ratio of the number of olefins vs. the number of non-hydrogen atoms. Linear and log plots of Emax vs. POL for a variety of molecules of the type R3Sb(O2CR')2 lend insight into the behaviour of these resists.

  7. Organometallic carboxylate resists for extreme ultraviolet with high sensitivity

    NASA Astrophysics Data System (ADS)

    Passarelli, James; Murphy, Michael; Re, Ryan Del; Sortland, Miriam; Hotalen, Jodi; Dousharm, Levi; Fallica, Roberto; Ekinci, Yasin; Neisser, Mark; Freedman, Daniel A.; Brainard, Robert L.

    2015-10-01

    We have developed organometallic carboxylate compounds [RnM)] capable of acting as negative-tone extreme ultraviolet (EUV) resists. The most sensitive of these resists contain antimony, three R-groups and two carboxylate groups, and carboxylate groups with polymerizable olefins (e.g., acrylate, methacrylate, or styrenecarboxylate). Evidence suggests that high sensitivity is achieved through the polymerization of olefins in the exposed region. We have performed a systematic sensitivity study of the molecules of the type RnM) where we have studied seven R groups, four main group metals (M), and three polymerizable carboxylate groups (O2CR‧). The sensitivity of these resists was evaluated using Emax or dose to maximum resist thickness after exposure and development. We found that the greatest predictor of sensitivity of the RnSb) resists is their level of polymerizable olefins. We mathematically define the polymerizable olefin loading (POL) as the ratio of the number of olefins versus the number of nonhydrogen atoms. Linear and log plots of Emax versus POL for a variety of molecules of the type R3Sb) lend insight into the behavior of these resists.

  8. Non-metallocene organometallic complexes and related methods and systems

    DOEpatents

    Agapie, Theodor; Golisz, Suzanne Rose; Tofan, Daniel; Bercaw, John E.

    2010-12-07

    A non-metallocene organometallic complex comprising a tridentate ligand and a metal bonded to a tridentate ligand, wherein two substituted aryl groups in the tridentate ligand are connected to a cyclic group at the ortho position via semi-rigid ring-ring linkages, and selected so to provide the resulting non-metallocene organometallic complex with a C.sub.S geometry, a C.sub.1 geometry, a C.sub.2 geometry or a C.sub.2v geometry. Method for performing olefin polymerization with a non-metallocene organometallic complex as a catalyst, related catalytic systems, tridentate ligand and method for providing a non-metallocene organometallic complex.

  9. Organometallic perovskites for optoelectronic applications (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Levchuk, Levgen; Hoegl, Florian; Brandl, Marco; Osvet, Andres; Hock, Rainer; Herre, Patrick; Wolfgang, Wolfgang; Schweizer, Peter; Spiecker, Erdmann; Batentschuk, Miroslaw; Brabec, Christoph

    2016-09-01

    Organometallic halide perovskites CH3NH3BX3 (B= Pb, Sn, Ge; X = I, Br, Cl) have become one of the most promising semiconductors for solar cell applications, reaching power conversion efficiencies beyond 20%. Improving our ability to harness the full potential of organometal halide perovskites requires the development of more reliable synthesis routines of well defined, reproducible and defect free reference systems allowing to study the fundamental photo-physical processes. In this study we present size and band gap engineering for organo-lead perovskites crystallites with various shapes and sizes ranging from the 5 nm regime all the way to 1 cm. Colloidal nano-crystals, micro-crystlline particles as well as single crystals are demonstrated with excellent purity and control in shape and size are demonstrated. The structural, optical and photo-physical properties of these reference materials are investigated and analyzed as function of their size and shape.

  10. Compound

    NASA Astrophysics Data System (ADS)

    Suzumura, Akitoshi; Watanabe, Masaki; Nagasako, Naoyuki; Asahi, Ryoji

    2014-06-01

    Recently, Cu-based chalcogenides such as Cu3SbSe4, Cu2Se, and Cu2SnSe3 have attracted much attention because of their high thermoelectric performance and their common feature of very low thermal conductivity. However, for practical use, materials without toxic elements such as selenium are preferable. In this paper, we report Se-free Cu3SbS4 thermoelectric material and improvement of its figure of merit ( ZT) by chemical substitutions. Substitutions of 3 at.% Ag for Cu and 2 at.% Ge for Sb lead to significant reductions in the thermal conductivity by 37% and 22%, respectively. These substitutions do not sacrifice the power factor, thus resulting in enhancement of the ZT value. The sensitivity of the thermal conductivity to chemical substitutions in these compounds is discussed in terms of the calculated phonon dispersion and previously proposed models for Cu-based chalcogenides. To improve the power factor, we optimize the hole carrier concentration by substitution of Ge for Sb, achieving a power factor of 16 μW/cm K2 at 573 K, which is better than the best reported for Se-based Cu3SbSe4 compounds.

  11. Half-metallicity in 2D organometallic honeycomb frameworks.

    PubMed

    Sun, Hao; Li, Bin; Zhao, Jin

    2016-10-26

    Half-metallic materials with a high Curie temperature (T C) have many potential applications in spintronics. Magnetic metal free two-dimensional (2D) half-metallic materials with a honeycomb structure contain graphene-like Dirac bands with π orbitals and show excellent aspects in transport properties. In this article, by investigating a series of 2D organometallic frameworks with a honeycomb structure using first principles calculations, we study the origin of forming half-metallicity in this kind of 2D organometallic framework. Our analysis shows that charge transfer and covalent bonding are two crucial factors in the formation of half-metallicity in organometallic frameworks. (i) Sufficient charge transfer from metal atoms to the molecules is essential to form the magnetic centers. (ii) These magnetic centers need to be connected through covalent bonding, which guarantee the strong ferromagnetic (FM) coupling. As examples, the organometallic frameworks composed by (1,3,5)-benzenetricarbonitrile (TCB) molecules with noble metals (Au, Ag, Cu) show half-metallic properties with T C as high as 325 K. In these organometallic frameworks, the strong electronegative cyano-groups (CN groups) drive the charge transfer from metal atoms to the TCB molecules, forming the local magnetic centers. These magnetic centers experience strong FM coupling through the d-p covalent bonding. We propose that most of the 2D organometallic frameworks composed by molecule-CN-noble metal honeycomb structures contain similar half metallicity. This is verified by replacing TCB molecules with other organic molecules. Although the TCB-noble metal organometallic framework has not yet been synthesized, we believe the development of synthesizing techniques and facility will enable the realization of them. Our study provides new insight into the 2D half-metallic material design for the potential applications in nanotechnology.

  12. Half-metallicity in 2D organometallic honeycomb frameworks

    NASA Astrophysics Data System (ADS)

    Sun, Hao; Li, Bin; Zhao, Jin

    2016-10-01

    Half-metallic materials with a high Curie temperature (T C) have many potential applications in spintronics. Magnetic metal free two-dimensional (2D) half-metallic materials with a honeycomb structure contain graphene-like Dirac bands with π orbitals and show excellent aspects in transport properties. In this article, by investigating a series of 2D organometallic frameworks with a honeycomb structure using first principles calculations, we study the origin of forming half-metallicity in this kind of 2D organometallic framework. Our analysis shows that charge transfer and covalent bonding are two crucial factors in the formation of half-metallicity in organometallic frameworks. (i) Sufficient charge transfer from metal atoms to the molecules is essential to form the magnetic centers. (ii) These magnetic centers need to be connected through covalent bonding, which guarantee the strong ferromagnetic (FM) coupling. As examples, the organometallic frameworks composed by (1,3,5)-benzenetricarbonitrile (TCB) molecules with noble metals (Au, Ag, Cu) show half-metallic properties with T C as high as 325 K. In these organometallic frameworks, the strong electronegative cyano-groups (CN groups) drive the charge transfer from metal atoms to the TCB molecules, forming the local magnetic centers. These magnetic centers experience strong FM coupling through the d-p covalent bonding. We propose that most of the 2D organometallic frameworks composed by molecule—CN—noble metal honeycomb structures contain similar half metallicity. This is verified by replacing TCB molecules with other organic molecules. Although the TCB-noble metal organometallic framework has not yet been synthesized, we believe the development of synthesizing techniques and facility will enable the realization of them. Our study provides new insight into the 2D half-metallic material design for the potential applications in nanotechnology.

  13. A robust microfluidic device for the synthesis and crystal growth of organometallic polymers with highly organized structures.

    PubMed

    Liu, Xiao; Yi, Qiaolian; Han, Yongzhen; Liang, Zhenning; Shen, Chaohua; Zhou, Zhengyang; Sun, Jun-Liang; Li, Yizhi; Du, Wenbin; Cao, Rui

    2015-02-02

    A simple and robust microfluidic device was developed to synthesize organometallic polymers with highly organized structures. The device is compatible with organic solvents. Reactants are loaded into pairs of reservoirs connected by a 15 cm long microchannel prefilled with solvents, thus allowing long-term counter diffusion for self-assembly of organometallic polymers. The process can be monitored, and the resulting crystalline polymers are harvested without damage. The device was used to synthesize three insoluble silver acetylides as single crystals of X-ray diffraction quality. Importantly, for the first time, the single-crystal structure of silver phenylacetylide was determined. The reported approach may have wide applications, such as crystallization of membrane proteins, synthesis and crystal growth of organic, inorganic, and polymeric coordination compounds, whose single crystals cannot be obtained using traditional methods.

  14. Local structure of Iridium organometallic catalysts covalently bonded to carbon nanotubes.

    NASA Astrophysics Data System (ADS)

    Blasco, J.; Cuartero, V.; Subías, G.; Jiménez, M. V.; Pérez-Torrente, J. J.; Oro, L. A.; Blanco, M.; Álvarez, P.; Blanco, C.; Menéndez, R.

    2016-05-01

    Hybrid catalysts based on Iridium N-heterocyclic carbenes anchored to carbon nanotubes (CNT) have been studied by XAFS spectroscopy. Oxidation of CNT yields a large amount of functional groups, mainly hydroxyl groups at the walls and carboxylic groups at the tips, defects and edges. Different kinds of esterification reactions were performed to functionalize oxidized CNT with imidazolium salts. Then, the resulting products were reacted with an Ir organometallic compound to form hybrid catalysts efficient in hydrogen transfer processes. XANES spectroscopy agree with the presence of Ir(I) in these catalysts and the EXAFS spectra detected differences in the local structure of Ir atoms between the initial Ir organometallic compound and the Ir complexes anchored to the CNT. Our results confirm that the halide atom, present in the Ir precursor, was replaced by oxygen from -OH groups at the CNT wall in the first coordination shell of Ir. The lability of this group accounts for the good recyclability and the good efficiency shown by these hybrid catalysts.

  15. Sulfur-bonded thiophenes in organometallic rhenium complexes and adsorption of isocyanides on gold

    SciTech Connect

    Robertson, Mitchell Joe

    1993-08-01

    This dissertation contains results of research conducted in two different areas: (1) organometallic synthesis and reactivity, and (2) organometallic surface chemistry. In the synthesis and reactivity studies, sulfur coordination of thiophene and benzo[b]thiophene to the metal center in organometallic rhenium complexes is examined. In the surface chemistry studies, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is used to analyze the adsorption of several isocyanides on the surface of gold powder. Results are compared and contrasted to known organometallic chemistry.

  16. Organic or organometallic template mediated clay synthesis

    SciTech Connect

    Gregar, K.C.; Winans, R.E.; Botto, R.E.

    1992-12-31

    A method is given for incorporating diverse varieties of intercalants or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and LiF for 2 days with an organic or organometallic intercalant or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by US patent No. 3,887,454 issued to Hickson, June 13, 1975; however, a variety of intercalants or templates may be introduced. The intercalants or templates should have water-solubility, positive charge, and thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays.

  17. Combinatorial screening of inorganic and organometallic materials

    DOEpatents

    Schultz, Peter G.; Xiang, Xiaodong; Goldwasser, Isy

    2002-01-01

    Methods and apparatus for the preparation and use of a substrate having an array of diverse materials in predefined regions thereon. A substrate having an array of diverse materials thereon is generally prepared by delivering components of materials to predefined regions on a substrate, and simultaneously reacting the components to form at least two materials. Materials which can be prepared using the methods and apparatus of the present invention include, for example, covalent network solids, ionic solids and molecular solids. More particularly, materials which can be prepared using the methods and apparatus of the present invention include, for example, inorganic materials, intermetallic materials, metal alloys, ceramic materials, organic materials, organometallic materials, non-biological organic polymers, composite materials (e.g., inorganic composites, organic composites, or combinations thereof), etc. Once prepared, these materials can be screened for useful properties including, for example, electrical, thermal, mechanical, morphological, optical, magnetic, chemical, or other properties. Thus, the present invention provides methods for the parallel synthesis and analysis of novel materials having useful properties.

  18. Organic or organometallic template mediated clay synthesis

    DOEpatents

    Gregar, K.C.; Winans, R.E.; Botto, R.E.

    1994-05-03

    A method is described for incorporating diverse varieties of intercalates or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and lithium fluoride for two days in the presence of an organic or organometallic intercalate or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue that are based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by U.S. Pat. No. 3,887,454 issued to Hickson, Jun. 13, 1975; however, a variety of intercalates or templates may be introduced. The intercalates or templates should have (i) water-solubility, (ii) positive charge, and (iii) thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays. 22 figures.

  19. Organic or organometallic template mediated clay synthesis

    DOEpatents

    Gregar, Kathleen C.; Winans, Randall E.; Botto, Robert E.

    1994-01-01

    A method for incorporating diverse Varieties of intercalants or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and lithium fluoride for two days in the presence of an organic or organometallic intercalant or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue that are based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by U.S. Pat. No. 3,887,454 issued to Hickson, Jun. 13, 1975; however, a variety of intercalants or templates may be introduced. The intercalants or templates should have (i) water-solubility, (ii) positive charge, and (iii) thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays.

  20. Ultrafast studies of organometallic photochemistry: The mechanism of carbon-hydrogen bond activation in solution

    SciTech Connect

    Bromberg, S.E.

    1998-05-01

    When certain organometallic compounds are photoexcited in room temperature alkane solution, they are able to break or activate the C-H bonds of the solvent. Understanding this potentially practical reaction requires a detailed knowledge of the entire reaction mechanism. Because of the dynamic nature of chemical reactions, time-resolved spectroscopy is commonly employed to follow the important events that take place as reactants are converted to products. For the organometallic reactions examined here, the electronic/structural characteristics of the chemical systems along with the time scales for the key steps in the reaction make ultrafast UV/Vis and IR spectroscopy along with nanosecond Step-Scan FTIR spectroscopy the ideal techniques to use for this study. An initial study of the photophysics of (non-activating) model metal carbonyls centering on the photodissociation of M(CO){sub 6} (M = Cr, W, Mo) was carried out in alkane solutions using ultrafast IR spectroscopy. Next, picosecond UV/vis studies of the C-H bond activation reaction of Cp{sup *}M(CO){sub 2} (M = Rh, Ir), conducted in room temperature alkane solution, are described in an effort to investigate the origin of the low quantum yield for bond cleavage ({approximately}1%). To monitor the chemistry that takes place in the reaction after CO is lost, a system with higher quantum yield is required. The reaction of Tp{sup *}Rh(CO){sub 2} (Tp{sup *} = HB-Pz{sub 3}{sup *}, Pz{sup *} = 3,5-dimethylpyrazolyl) in alkanes has a quantum yield of {approximately}30%, making time resolved spectroscopic measurements possible. From ultrafast IR experiments, two subsequently formed intermediates were observed. The nature of these intermediates are discussed and the first comprehensive reaction mechanism for a photochemical C-H activating organometallic complex is presented.

  1. Modules for Introducing Organometallic Reactions: A Bridge between Organic and Inorganic Chemistry

    ERIC Educational Resources Information Center

    Schaller, Chris P.; Graham, Kate J.; Johnson, Brian J.

    2015-01-01

    Transition metal organometallic reactions have become increasingly important in the synthesis of organic molecules. A new approach has been developed to introduce organometallic chemistry, along with organic and inorganic chemistry, at the foundational level. This change highlights applications of organometallic chemistry that have dramatically…

  2. A "Classic Papers" Approach to Teaching Undergraduate Organometallic Chemistry

    NASA Astrophysics Data System (ADS)

    Duncan, Andrew P.; Johnson, Adam R.

    2007-03-01

    We have structured an upper-level undergraduate course in organometallic chemistry on a selection of "classic" publications in the field. This approach offers students a richly contextual introduction to many of the fundamental tenets of the discipline. After a brief introduction to the field led by the faculty, the students themselves are responsible for researching and presenting selected papers to their classmates for analysis and discussion. Beyond mastery of basic organometallic principles, course goals for the students include improved proficiency in using the primary chemical literature and increased experience and confidence in researching, preparing, and delivering an informative oral presentation in individual and collaborative settings. Student performance is assessed based on performance on open-ended, take-home exams, quality of presentations, and contribution to in-class discussions. Student end-of-term survey responses indicate that this class model is successful as an introduction to organometallic chemistry.

  3. Slip Analysis in a Ni-base Superalloy

    NASA Technical Reports Server (NTRS)

    Westbrooke, Eboni F.; Forero, Luis E.; Ebrahimi, Fereshteh

    2004-01-01

    A Ni-base superalloy single crystal with Gamma/Gamma' structure was tested at room temperature along the , <110> and <111> directions. Consistent with previously reported investigations, this alloy did not obey the Schmid law and the CRSS (critical resolved shear stress) was noticeably lower for the <111>-oriented samples. Furthermore, the strain hardening rate decreased and the degree of deformation localization increased in the order of <111>, and <110> orientations. The appearance and orientation of deformation traces were found to depend on the loading orientation as well as the amount of strain. In general, when Gamma'-particles were sheared, the traces followed the expected octahedral shear planes. It is demonstrated that the wavy deformation traces that do not follow the {111} planes are associated with changes in the gamma-channels width and the falling off of the gamma-particles. In this paper the evolution of deformation bands are discussed in terms of plastic localization at microscopic, mesoscopic and macroscopic levels.

  4. Microstructural and Chemical Rejuvenation of a Ni-Based Superalloy

    NASA Astrophysics Data System (ADS)

    Yao, Zhiqi; Degnan, Craig C.; Jepson, Mark A. E.; Thomson, Rachel C.

    2016-12-01

    The microstructural evolution of the Ni-based superalloy CMSX-4 including the change in gamma prime morphology, size, and distribution after high-temperature degradation and subsequent rejuvenation heat treatments has been examined using field emission gun scanning electron microscopy and transmission electron microscopy. In this paper, it is shown that there are significant differences in the size of the `channels' between gamma prime particles, the degree of rafting, and the size of tertiary gamma prime particles in each of the different microstructural conditions studied. Chemical analysis has been carried out to compare rejuvenated and pre-service samples after the same subsequent degradation procedure. The results indicate that although the microstructures of pre-service and rejuvenated samples are similar, chemical differences are more pronounced in the rejuvenated samples, suggesting that chemical segregation from partitioning of the elements was not completely eliminated through the applied rejuvenation heat treatment. A number of modified rejuvenation heat treatment trials were carried out to reduce the chemical segregation prior to creep testing. The creep test results suggest that chemical segregation has an immeasurable influence on the short-term mechanical properties under the test conditions used here, indicating that further work is required to fully understand the suitability of specific rejuvenation heat treatments and their role in the extension of component life in power plant applications.

  5. Direct borohydride fuel cell using Ni-based composite anodes

    NASA Astrophysics Data System (ADS)

    Ma, Jia; Sahai, Yogeshwar; Buchheit, Rudolph G.

    In this study, nickel-based composite anode catalysts consisting of Ni with either Pd on carbon or Pt on carbon (the ratio of Ni:Pd or Ni:Pt being 25:1) were prepared for use in direct borohydride fuel cells (DBFCs). Cathode catalysts used were 1 mg cm -2 Pt/C or Pd electrodeposited on activated carbon cloth. The oxidants were oxygen, oxygen in air, or acidified hydrogen peroxide. Alkaline solution of sodium borohydride was used as fuel in the cell. High power performance has been achieved by DBFC using non-precious metal, Ni-based composite anodes with relatively low anodic loading (e.g., 270 mW cm -2 for NaBH 4/O 2 fuel cell at 60 °C, 665 mW cm -2 for NaBH 4/H 2O 2 fuel cell at 60 °C). Effects of temperature, oxidant, and anode catalyst loading on the DBFC performance were investigated. The cell was operated for about 100 h and its performance stability was recorded.

  6. Ni-based nanoalloys: Towards thermally stable highly magnetic materials

    SciTech Connect

    Palagin, Dennis Doye, Jonathan P. K.

    2014-12-07

    Molecular dynamics simulations and density functional theory calculations have been used to demonstrate the possibility of preserving high spin states of the magnetic cores within Ni-based core-shell bimetallic nanoalloys over a wide range of temperatures. We show that, unlike the case of Ni–Al clusters, Ni–Ag clusters preserve high spin states (up to 8 μ{sub B} in case of Ni{sub 13}Ag{sub 32} cluster) due to small hybridization between the electronic levels of two species. Intriguingly, such clusters are also able to maintain geometrical and electronic integrity of their cores at temperatures up to 1000 K (e.g., for Ni{sub 7}Ag{sub 27} cluster). Furthermore, we also show the possibility of creating ordered arrays of such magnetic clusters on a suitable support by soft-landing pre-formed clusters on the surface, without introducing much disturbance in geometrical and electronic structure of the cluster. We illustrate this approach with the example of Ni{sub 13}Ag{sub 38} clusters adsorbed on the Si(111)–(7×7) surface, which, having two distinctive halves to the unit cell, acts as a selective template for cluster deposition.

  7. Recent applications of polymer supported organometallic catalysts in organic synthesis.

    PubMed

    Kann, Nina

    2010-09-07

    Recent developments concerning the application of polymer supported organometallic reagents in solid phase synthesis are reviewed, with a special focus on methodology for carbon-carbon formation. Examples of reactions that are covered include the classical Suzuki, Sonogashira and Heck coupings, but also aryl amination, epoxide opening, rearrangements, metathesis and cyclopropanation. Applications in the field of asymmetric synthesis are also discussed.

  8. Organometalic carbosilane polymers containing vanadium and their preparation

    NASA Technical Reports Server (NTRS)

    Yajima, S.; Okamura, K.; Shishido, T.; Fukuda, K.

    1983-01-01

    The present invention concerns a new organometallic polymer material containing in part a vanadium-siloxane linkage (V-0-Si), which has excellent resistance to heat and oxidation and a high residue ratio after high temperature treatment in a non-oxidizing atmosphere, for example, nitrogen, argon, helium, ammonia, or hydrogen.

  9. In –Situ Spectroscopic Investigation of Immobilized Organometallic Catalysts

    SciTech Connect

    Davis, Robert, J.

    2007-11-14

    Immobilized organometallic catalysts, in principle, can give high rates and selectivities like homogeneous catalysts with the ease of separation enjoyed by heterogeneous catalysts. However, the science of immobilized organometallics has not been developed because the field lies at the interface between the homogeneous and heterogeneous catalysis communities. By assembling an interdisciplinary research team that can probe all aspects of immobilized organometallic catalyst design, the entire reacting system can be considered, where the transition metal complex, the complex-support interface and the properties of the support can all be considered simultaneously from both experimental and theoretical points of view. Researchers at Georgia Tech and the University of Virginia are studying the fundamental principles that can be used to understand and design future classes of immobilized organometallic catalysts. In the framework of the overall collaborative project with Georgia Tech, our work focused on (a) the X-ray absorption spectroscopy of an immobilized Pd-SCS-O complex (b) the mode of metal leaching from supported Pd catalysts during Heck catalysis and (c) the mode of deactivation of Jacobsen’s Co-salen catalysts during the hydrolytic kinetic resolution of terminal epoxides. Catalysts containing supported Pd pincer complexes, functionalized supports containing mercapto and amine groups, and oligomeric Co-salen catalysts were synthesized at Georgia Tech and sent to the University of Virginia. Incorporation of Pd onto several different kinds of supports (silica, mercapto-functionalized silica, zeolite Y) was performed at the University of Virginia.

  10. Rational design of an organometallic glutathione transferase inhibitor

    SciTech Connect

    Ang, W.H.; Parker, L.J.; De Luca, A.; Juillerat-Jeanneret, L.; Morton, C.J.; LoBello, M.; Parker, M.W.; Dyson, P.J.

    2010-08-17

    A hybrid organic-inorganic (organometallic) inhibitor was designed to target glutathione transferases. The metal center is used to direct protein binding, while the organic moiety acts as the active-site inhibitor. The mechanism of inhibition was studied using a range of biophysical and biochemical methods.

  11. ROMP Synthesis of Iron-Containing Organometallic Polymers.

    PubMed

    Dragutan, Ileana; Dragutan, Valerian; Filip, Petru; Simionescu, Bogdan C; Demonceau, Albert

    2016-02-06

    The paper overviews iron-containing polymers prepared by controlled "living" ring-opening metathesis polymerization (ROMP). Developments in the design and synthesis of this class of organometallic polymers are highlighted, pinpointing methodologies and newest trends in advanced applications of hybrid materials based on polymers functionalized with iron motifs.

  12. Ligand Rearrangements of Organometallic Complexes inSolution

    SciTech Connect

    Shanoski, Jennifer E.

    2006-01-01

    Many chemical reactions utilize organometallic complexes as catalysts. These complexes find use in reactions as varied as bond activation, polymerization, and isomerization. This thesis outlines the construction of a new ultrafast laser system with an emphasis on the generation of tunable mid-infrared pulses, data collection, and data analysis.

  13. Strategies to prepare and use functionalized organometallic reagents.

    PubMed

    Klatt, Thomas; Markiewicz, John T; Sämann, Christoph; Knochel, Paul

    2014-05-16

    Polyfunctional zinc and magnesium organometallic reagents occupy a central position in organic synthesis. Most organic functional groups are tolerated by zinc organometallic reagents, and Csp(2)-centered magnesium organometallic reagents are compatible with important functional groups, such as the ester, aryl ketone, nitro, cyano, and amide functions. This excellent chemoselectivity gives zinc- and magnesium-organometallic reagents a central position in modern organic synthesis. Efficient and general preparations of these organometallic reagents, as well as their most practical and useful reactions, are presented in this Perspective. As starting materials, a broad range of organic halides (iodides, bromides, and also to some extent chlorides) can be used for the direct insertion of magnesium or zinc powder; the presence of LiCl very efficiently promotes such insertions. Alternatively, aromatic or heterocyclic bromides also undergo a smooth bromine-magnesium exchange when treated with i-PrMgCl·LiCl. Alternative precursors of zinc and magnesium reagents are polyfunctionalized aryl and heteroaryl molecules, which undergo directed metalations with sterically hindered TMP bases (TMP = 2,2,6,6-tetramethylpiperide) of magnesium and zinc. This powerful C-H functionalization method gives access to polyfunctional heterocyclic zinc and magnesium reagents, which undergo efficient reactions with numerous electrophiles. The compatibility of the strong TMP-bases with BF3·OEt2 (formation of frustrated Lewis pairs) dramatically increases the scope of these metalations, giving for example, a practical access to magnesiated pyridines and pyrazines, which can be used as convenient building blocks for the preparation of biologically active molecules.

  14. Fluoroalkylation of organic compounds

    NASA Astrophysics Data System (ADS)

    Mikhaylov, D. Yu; Budnikova, Yu H.

    2013-09-01

    Data on fluoroalkylation and perfluoroalkylation methods in organic synthesis are analyzed, summarized and described systematically. The most practically important properties of compounds with fluoroalkyl substituents are illustrated. The key trends and the potential of this field of organic chemistry are considered. Electrochemical syntheses of perfluoroalkyl derivatives that are inaccessible or experimentally difficult to prepare by regular chemical techniques are presented. Particular attention is paid to processes involving organometallic compounds as well as to prospects for the development of this field of research. The bibliography includes 226 references.

  15. In situ electrochemical activation of Ni-based colloids from an NiCl2 electrode and their advanced energy storage performance.

    PubMed

    Chen, Kunfeng; Xue, Dongfeng

    2016-10-06

    The formation of electrochemical activated cations in electrode materials to induce multiple-electron transfer reactions is a challenge for high-energy storage systems. Herein, highly electroactive Ni-based colloidal electrode materials have been synthesized by in situ electrochemical activation of a NiCl2 electrode. The highest specific capacitance of the activated Ni-based electrodes was 10 286 F g(-1) at a current density of 3 A g(-1), indicating that a three-electron Faradaic redox reaction (Ni(3+) ↔ Ni) occurred. Upon potential cycling and constant potential activation, a decrease in the charge transfer resistance can be found. Activation and utilization of multiple-electron reactions is an efficient route to increase the energy density of supercapacitors. This newly designed colloidal pseudocapacitor is compatible with inorganic pseudocapacitor chemistry, which enables us to use metal cations directly via their commercial salts rather than their oxide/hydroxide compounds.

  16. MALDI-TOFMS analysis of coordination and organometallic complexes: a nic(h)e area to work in.

    PubMed

    Wyatt, Mark F

    2011-07-01

    A mini-review of the characterisation of metal-containing compounds by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) is presented. Organometallic and coordination compounds have many varied applications, most notably in industrial catalytic processes and also in the electronics and healthcare sectors. In general, the compounds discussed, be they small or large molecules, have a high percentage metal content, rather than simply containing 'a metal atom'. A brief history of the field is given, but the main scope over the last 5 years is covered in some detail. How MALDI-TOFMS compliments electrospray for metal-containing compounds is highlighted. Perspectives on recent advances, such as solvent-free and air/moisture-sensitive sample preparation, and potential future challenges and developments, such as nanomaterials and metallodrug/metallometabolite imaging, are given.

  17. Organometallic Chemical Vapor Deposition of ZrF4-Based Fluoride Glasses

    NASA Astrophysics Data System (ADS)

    Fujiura, Kazuo; Ohishi, Yasutake; Takahashi, Shiro

    1989-01-01

    By organometallic chemical vapor deposition (OMCVD), fluoride glasses in a ZrF4-BaF2 binary system are successfully synthesized. β-Diketone chelates of Zr and Ba as starting materials can be volatilized and completely fluorinated with HF gas into ZrF4-BaF2 compounds. 65 mol%ZrF4-35 mol%BaF2 powder synthesized by OMCVD is identified as homogeneous glass by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). By this method, ZrF4 is also obtained in an amorphous state. The OMCVD is available for preparation of fluoride glass, which is promising for optical fiber.

  18. Femtosecond Time-Resolved Infrared Spectra of Organometallic Complexes Bound to a Dinuclear Metal Center

    NASA Astrophysics Data System (ADS)

    Brown-Xu, Samantha E.; Durr, Christopher B.

    2012-06-01

    Compounds of the form M2L2L'2, where M2 is a quadruply bonded metal center (M = Mo or W) and L and L' are conjugated organic ligands, are known to show interesting photophysical properties and exhibit intense metal-to-ligand charge transfer (MLCT) transitions throughout the visible spectrum. Recently, we have modified one of the ligands to incorporate a transition metal carbonyl complex bound to an organic moiety. Following excitation into the MLCT band, the vibrational modes of the organometallic ligand can be observed by fs time-resolved infrared (TRIR) spectroscopy. This allows for a visualization of where the electron density resides in the excited states, which provides useful information for designing new materials that could later be incorporated into solar devices.

  19. Iron-Catalyzed C-C Cross-Couplings Using Organometallics.

    PubMed

    Guérinot, Amandine; Cossy, Janine

    2016-08-01

    Over the last decades, iron-catalyzed cross-couplings have emerged as an important tool for the formation of C-C bonds. A wide variety of alkenyl, aryl, and alkyl (pseudo)halides have been coupled to organometallic reagents, the most currently used being Grignard reagents. Particular attention has been devoted to the development of iron catalysts for the functionalization of alkyl halides that are generally challenging substrates in classical cross-couplings. The high functional group tolerance of iron-catalyzed cross-couplings has encouraged organic chemists to use them in the synthesis of bioactive compounds. Even if some points remain obscure, numerous studies have been carried out to investigate the mechanism of iron-catalyzed cross-coupling and several hypotheses have been proposed.

  20. Estimate of conjugate gamma and gamma prime compositions in Ni-base superalloys

    NASA Technical Reports Server (NTRS)

    Dreshfield, R. L.

    1977-01-01

    Approaches for estimating the composition of the matrix phase of alloys from the melt composition are reviewed. The first method is based on assigning essentially fixed stoichiometry to precipitating phases and is typified by PHACOMP. The second method uses analytical geometry to interpret phase diagrams and is applicable to a two-phase region of a six-component Ni-base system. The geometric method is also applicable to commercial Ni-base superalloys.

  1. Effectiveness of various organometallics as antiwear additives in mineral oil

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1977-01-01

    Sliding friction experiments were conducted with 1045 steel contacting 302 stainless steel and lubricated with various organometallics in mineral oil. Auger emission spectroscopy was used to determine the element present in the wear contact zone. The results indicate that there are organometallics which are as effective an antiwear additives as the commonly used zinc dialkyl dithiophosphate. These include dimethyl cadmium, triphenyl lead thiomethoxide, and triphenyl tin chloride. The additives were examined in concentrations to 1 weight percent. With dimethyl cadmium at concentrations of 0.5 weight percent and above, cadmium was detected in the contact zone. Coincident with the detection of cadmium, a marked decrease in the friction coefficient was observed. All additives examined reduced friction, but only the aforementioned reduced wear to a level comparable to that observed with zinc dialkyl dithiophosphate.

  2. An Organometallic Future in Green and Energy Chemistry?

    SciTech Connect

    Crabtree, Robert H

    2011-01-10

    The title topic is reviewed with selected examples taken from recent work, such as: the 'hydrogen borrowing' amine alkylation by alcohols; the dehydrogenative coupling of amine and alcohol to give amide; Ru complexes as solar cell photosensitizers; Ir organometallics as water oxidation catalyst precursors and as OLED emitters; as well as recent hydrogen storage strategies involving catalytic dehydrogenation of ammonia-borane and of organic heterocycles.

  3. Sunlight induced cycloaddition and host-guest property of self-assembled organometallic macrocycles based on a versatile building block.

    PubMed

    Wu, Tong; Weng, Lin-Hong; Jin, Guo-Xin

    2012-05-11

    Organometallic rectangle 1 which undergoes [2+2] cycloaddition upon irradiation with sunlight and organometallic prism 3 which displayed interesting host-guest property were self-assembled based on a versatile building block.

  4. Computational Raman spectroscopy of organometallic reaction products in lithium and sodium-based battery systems.

    PubMed

    Sánchez-Carrera, Roel S; Kozinsky, Boris

    2014-11-28

    A common approach to understanding surface reaction mechanisms in rechargeable lithium-based battery systems involves spectroscopic characterization of the product mixtures and matching of spectroscopic features to spectra of pure candidate reference compounds. This strategy, however, requires separate chemical synthesis and accurate characterization of potential reference compounds. It also assumes that atomic structures are the same in the actual product mixture as in the reference samples. We propose an alternative approach that uses first-principles computations of spectra of the possible reaction products and by-products present in advanced battery systems. We construct a library of computed Raman spectra for possible products, achieving excellent agreement with reference experimental data, targeting solid-electrolyte interphase in Li-ion cells and discharge products of Li-air cells. However, the solid-state crystalline structure of Li(Na) metal-organic compounds is often not known, making the spectra computations difficult. We develop and apply a novel technique of simplifying spectra calculations by using dimer-like representations of the solid state structures. On the basis of a systematic investigation, we demonstrate that molecular dimers of Li(Na)-based organometallic material provide relevant information about the vibrational properties of many possible solid reaction products. Such an approach should serve as a basis to extend existing spectral libraries of molecular structures relevant for understanding the link between atomic structures and measured spectroscopic data of materials in novel battery systems.

  5. Field-induced conductance switching by charge-state alternation in organometallic single-molecule junctions

    NASA Astrophysics Data System (ADS)

    Schwarz, Florian; Kastlunger, Georg; Lissel, Franziska; Egler-Lucas, Carolina; Semenov, Sergey N.; Venkatesan, Koushik; Berke, Heinz; Stadler, Robert; Lörtscher, Emanuel

    2016-02-01

    Charge transport through single molecules can be influenced by the charge and spin states of redox-active metal centres placed in the transport pathway. These intrinsic properties are usually manipulated by varying the molecule's electrochemical and magnetic environment, a procedure that requires complex setups with multiple terminals. Here we show that oxidation and reduction of organometallic compounds containing either Fe, Ru or Mo centres can solely be triggered by the electric field applied to a two-terminal molecular junction. Whereas all compounds exhibit bias-dependent hysteresis, the Mo-containing compound additionally shows an abrupt voltage-induced conductance switching, yielding high-to-low current ratios exceeding 1,000 at bias voltages of less than 1.0 V. Density functional theory calculations identify a localized, redox-active molecular orbital that is weakly coupled to the electrodes and closely aligned with the Fermi energy of the leads because of the spin-polarized ground state unique to the Mo centre. This situation provides an additional slow and incoherent hopping channel for transport, triggering a transient charging effect in the entire molecule with a strong hysteresis and large high-to-low current ratios.

  6. Preparation and characterization of Ni-based perovskite catalyst for steam CO2 reforming of methane.

    PubMed

    Yang, Eun-Hyeok; Kim, Sang Woo; Ahn, Byong Song; Moon, Dong Ju

    2013-06-01

    Steam CO2 reforming of methane was investigated over Ni-based perovskite catalyst to produce desired H2/CO ratio by adjusting the feed ratio of CH4, CO2 and H2O for floating GTL process application. La modified perovskites were prepared by the Pechini method and calcined in air and the Ni-based catalysts were prepared by dispersing Ni on the La modified perovskite by an incipient wetness impregnation. The catalysts before and after the reaction were characterized by N2 physisoprtion, CO chemisoprtion, XRD, TPR and SEM techniques. To control desired H2/CO ratio, simulation for SCR was carried out by Aspen plus, and product distribution for SCR was investigated in a fixed bed reactor system using feed ratio estimated by simulation. The Ni-based perovskite catalysts were found to give CH4 and CO2 conversions of up to 82% and 60% respectively to yield a H2/CO product ratio close to 2.

  7. A Review on Inertia and Linear Friction Welding of Ni-Based Superalloys

    NASA Astrophysics Data System (ADS)

    Chamanfar, Ahmad; Jahazi, Mohammad; Cormier, Jonathan

    2015-04-01

    Inertia and linear friction welding are being increasingly used for near-net-shape manufacturing of high-value materials in aerospace and power generation gas turbines because of providing a better quality joint and offering many advantages over conventional fusion welding and mechanical joining techniques. In this paper, the published works up-to-date on inertia and linear friction welding of Ni-based superalloys are reviewed with the objective to make clarifications on discrepancies and uncertainties reported in literature regarding issues related to these two friction welding processes as well as microstructure, texture, and mechanical properties of the Ni-based superalloy weldments. Initially, the chemical composition and microstructure of Ni-based superalloys that contribute to the quality of the joint are reviewed briefly. Then, problems related to fusion welding of these alloys are addressed with due consideration of inertia and linear friction welding as alternative techniques. The fundamentals of inertia and linear friction welding processes are analyzed next with emphasis on the bonding mechanisms and evolution of temperature and strain rate across the weld interface. Microstructural features, texture development, residual stresses, and mechanical properties of similar and dissimilar polycrystalline and single crystal Ni-based superalloy weldments are discussed next. Then, application of inertia and linear friction welding for joining Ni-based superalloys and related advantages over fusion welding, mechanical joining, and machining are explained briefly. Finally, present scientific and technological challenges facing inertia and linear friction welding of Ni-based superalloys including those related to modeling of these processes are addressed.

  8. 2012 ORGANOMETALLIC CHEMISTRY GRC/GRS, JULY 7-13, 2012

    SciTech Connect

    Hillhouse, Gregory

    2012-07-13

    The 2012 Organometallic Chemistry Gordon Research Conference will highlight new basic science and fundamental applications of organometallic chemistry in industrial, academic, and national lab settings. Scientific themes of the conference will include chemical synthesis, reactivity, catalysis, polymer chemistry, bonding, and theory that involve transition-metal (and main-group) interactions with organic moieties.

  9. [Progress of organometallic complexes and their application to organic electroluminescent materials].

    PubMed

    Zhou, Rui; An, Zhong-Wei; Chai, Sheng-Yong

    2004-08-01

    Organic electroluminescent (EL) material is one of most prospective display materials in flat panel display. Organometallic complexes, which have five or six member ring structures, with high stability, high melting point and high fluorescence quantum efficiency, are widely applied in organic EL devices. The recent progress in organometallic complexes is summarized in terms of the electroluminescence of ligands and metal atoms.

  10. New Twists and Turns for Actinide Chemistry: Organometallic Infinite Coordination Polymers of Thorium Diazide.

    PubMed

    Monreal, Marisa J; Seaman, Lani A; Goff, George S; Michalczyk, Ryszard; Morris, David E; Scott, Brian L; Kiplinger, Jaqueline L

    2016-03-07

    Two organometallic 1D infinite coordination polymers and two organometallic monometallic complexes of thorium diazide have been synthesized and characterized. Steric control of these self-assembled arrays, which are dense in thorium and nitrogen, has also been demonstrated: infinite chains can be circumvented by using steric bulk either at the metallocene or with a donor ligand in the wedge.

  11. A study on coke deposition in Ni-based catalysts for CO2 reforming of methane

    NASA Astrophysics Data System (ADS)

    Yahya, Erny Azwin; Zabidi, Noor Asmawati Mohd; Kait, Chong Fai

    2016-11-01

    Cobalt (Co) and niobium (Nb) promoted Ni-based catalysts have been prepared by a wet impregnation method. The influence of these promoters on properties and performance of Ni-based catalyst supported on γ-Al2O3 for CO2 reforming of methane reaction has been studied. CO2 reforming of methane reaction has been conducted at atmospheric pressure for 5 h at 850 °C. Results show that Nb promoted catalysts show higher conversion of CH4 and CO2 (44.5%) compared to that of unpromoted catalyst. Meanwhile, the amount of coke formed was lower on the promoted catalysts compared to that of unpromoted catalyst.

  12. Effect of Surface Roughness on the Oxidation Behavior of the Ni-Base Superalloy ME3

    NASA Astrophysics Data System (ADS)

    Evans, Jeffrey L.

    2010-10-01

    Ni-base superalloys are used in applications, such as jet aircraft engines and power production facilities that require excellent elevated temperature oxidation resistance. This present work evaluated the effect of surface roughness on the oxidation behavior of the Ni-base superalloy ME3. Isothermal oxidation tests were performed in air at different times to investigate the oxide growth kinetics. The surface oxides were also characterized using scanning electron microscopy and x-ray diffraction. The surface roughness was measured using a linear scanning profilometer. The surface roughness measurements were correlated to the oxidation rates and an empirical model is proposed to describe the effect of surface roughness on the oxidation behavior.

  13. Irradiation effects in oxide dispersion strengthened (ODS) Ni-base alloys for Gen. IV nuclear reactors

    NASA Astrophysics Data System (ADS)

    Oono, Naoko; Ukai, Shigeharu; Kondo, Sosuke; Hashitomi, Okinobu; Kimura, Akihiko

    2015-10-01

    Oxide particle dispersion strengthened (ODS) Ni-base alloys are irradiated by using simulation technique (Fe/He dual-ion irradiation) to investigate the reliability to Gen. IV high-temperature reactors. The fine oxide particles with less than 10 nm in average size and approximately 8.0 × 1022 m-3 in number density remained after 101 dpa irradiation. The tiny helium bubbles were inside grains, not at grain-boundaries; it is advantageous effect of oxide particles which trap the helium atoms at the particle-matrix interface. Ni-base ODS alloys demonstrated their great ability to overcome He embrittlement.

  14. Supported organometallic complexes, surface chemistry, spectroscopy, and catalysis

    SciTech Connect

    Marks, T.J.

    1993-04-01

    Goal is to elucidate and understand the surface chemistry and catalytic properties of well-defined, highly-reactive organometallic molecules (principally based upon abundant actinide, lanthanide, and early transition elements) adsorbed on metal oxides and halides. Nature of adsorbed species is probed by a battery of chemical and physicochemical techniques, to understand the nature of the molecule-surface coordination chemistry and how this can give rise to extremely high catalytic activity. A complementary objective is to delineate the scope and mechanisms of the heterogeneous catalytic reactions, as well as to relate them both conceptually and functionally to model systems generated in solution.

  15. Fundamental organometallic reactions: Applications on the CYBER 205

    NASA Technical Reports Server (NTRS)

    Rappe, A. K.

    1984-01-01

    Two of the most challenging problems of Organometallic chemistry (loosely defined) are pollution control with the large space velocities needed and nitrogen fixation, a process so capably done by nature and so relatively poorly done by man (industry). For a computational chemist these problems are on the fringe of what is possible with conventional computers (large models needed and accurate energetics required). A summary of the algorithmic modification needed to address these problems on a vector processor such as the CYBER 205 and a sketch of findings to date on deNOx catalysis and nitrogen fixation are presented.

  16. Growth and characterization of GaAs, AlGaAs and their heterostructures by organometallic vapor phase epitaxy

    SciTech Connect

    Shealy, J.R.

    1983-01-01

    Organometallic Vapor Phase Epitaxy (OMVPE) is a cold wall vapor desposition technique using organometallic and/or hydride sources for the fabrication of a variety of epitaxial compound semiconductor alloys on suitable substrates. The use of the OMVPE process to produce high quality GaAs, AlGaAs, and their heterostructures on GaAs substrates using trimethygalium (TMG), trimethylalumium (TMA), and arsine is described. For GaAs epitaxial films, the unintentional residual donor sand acceptors have been identified using far-infrared photo-ionization data, and low temperature photoluminescence, respectively, and their concentrations have been evaluated using Hall data. For the growth of AlGaAs films, it was observed that poor quality films were obtained due to oxygen contamination of the layer during growth. A series of graded bandgap heterostructures and abrupt quantum well heterostructures were grown over a variety of growth conditions. Composition gradings were controlled over a full range of alloy compositions on distances as small as 500 - 1000 A, and a 40 A quantum well heterostructure was obtained at low growth temperatures (550/sup 0/C). Finally, results are presented on a few devices which incorporate metallurgical junctions and heterojunctions with the GaAs/AlGaAs system. These devices include a microwave vertical FET structure, graded bandgap solar cells, and light emitting diodes.

  17. Magnetic Exchange Interactions in Long Range Ordered Diluted Organometallic Semiconductors

    NASA Astrophysics Data System (ADS)

    Rawat, Naveen; Manning, Lane; Furis, Madalina

    2015-03-01

    Exchange Interactions in diluted organometallic crystalline thin films of Phthalocyanines made of a mixture of organo-soluble derivatives of metal-free (H2Pc) molecule and MnPc is investigated. The tuning of optical and magnetic properties in organometallics is driven by their emergence in optoelectronic applications involving flexible electronics. Thin films with metal to metal-free Pc ratios ranging from 1: 1 to 1:10 were fabricated using solution processing that produces macroscopic grains. In the case of Mn-Pc, our previos measurements showed enhanced hybridization of ligand π-electronic states with the Mn d-orbitals as well as indirect exchange interaction similar to that of RKKY type exchange. The evolution of Zeeman splitting of specific MCD-active states resulted in enhanced effective π-electrons g-factors, analogous to diluted magnetic semiconductors (DMS) systems. Recent Variable temperature Magnetic Circular Dichroism (VTVH-MCD) measurements has now revealed that the exchange interaction is Antiferromagnetic. Recent MCD data for mixed derivatives will be presented along with their temperature dependance that further probes this exchange interaction. NSF award 1056589

  18. Two-Photon Absorption in Organometallic Bromide Perovskites.

    PubMed

    Walters, Grant; Sutherland, Brandon R; Hoogland, Sjoerd; Shi, Dong; Comin, Riccardo; Sellan, Daniel P; Bakr, Osman M; Sargent, Edward H

    2015-09-22

    Organometallic trihalide perovskites are solution-processed semiconductors that have made great strides in third-generation thin film light-harvesting and light-emitting optoelectronic devices. Recently, it has been demonstrated that large, high-purity single crystals of these perovskites can be synthesized from the solution phase. These crystals' large dimensions, clean bandgap, and solid-state order have provided us with a suitable medium to observe and quantify two-photon absorption in perovskites. When CH3NH3PbBr3 single crystals are pumped with intense 800 nm light, we observe band-to-band photoluminescence at 572 nm, indicative of two-photon absorption. We report the nonlinear absorption coefficient of CH3NH3PbBr3 perovskites to be 8.6 cm GW(-1) at 800 nm, comparable to epitaxial single-crystal semiconductors of similar bandgap. We have leveraged this nonlinear process to electrically autocorrelate a 100 fs pulsed laser using a two-photon perovskite photodetector. This work demonstrates the viability of organometallic trihalide perovskites as a convenient and low-cost nonlinear absorber for applications in ultrafast photonics.

  19. Reactive codoping of GaAlInP compound semiconductors

    DOEpatents

    Hanna, Mark Cooper; Reedy, Robert

    2008-02-12

    A GaAlInP compound semiconductor and a method of producing a GaAlInP compound semiconductor are provided. The apparatus and method comprises a GaAs crystal substrate in a metal organic vapor deposition reactor. Al, Ga, In vapors are prepared by thermally decomposing organometallic compounds. P vapors are prepared by thermally decomposing phospine gas, group II vapors are prepared by thermally decomposing an organometallic group IIA or IIB compound. Group VIB vapors are prepared by thermally decomposing a gaseous compound of group VIB. The Al, Ga, In, P, group II, and group VIB vapors grow a GaAlInP crystal doped with group IIA or IIB and group VIB elements on the substrate wherein the group IIA or IIB and a group VIB vapors produced a codoped GaAlInP compound semiconductor with a group IIA or IIB element serving as a p-type dopant having low group II atomic diffusion.

  20. Towards cancer cell-specific phototoxic organometallic rhenium(I) complexes.

    PubMed

    Leonidova, Anna; Pierroz, Vanessa; Rubbiani, Riccardo; Heier, Jakob; Ferrari, Stefano; Gasser, Gilles

    2014-03-21

    Over the recent years, several Re(I) organometallic compounds have been shown to be toxic to various cancer cell lines. However, these compounds lacked sufficient selectivity towards cancer tissues to be used as novel chemotherapeutic agents. In this study, we probe the potential of two known N,N-bis(quinolinoyl) Re(I) tricarbonyl complex derivatives, namely Re(I) tricarbonyl [N,N-bis(quinolin-2-ylmethyl)amino]-4-butane-1-amine (Re-NH₂) and Re(I) tricarbonyl [N,N-bis(quinolin-2-ylmethyl)amino]-5-valeric acid (Re-COOH), as photodynamic therapy (PDT) photosensitizers. Re-NH₂ and Re-COOH proved to be excellent singlet oxygen generators in a lipophilic environment with quantum yields of about 75%. Furthermore, we envisaged to improve the selectivity of Re-COOH via conjugation to two types of peptides, namely a nuclear localization signal (NLS) and a derivative of the neuropeptide bombesin, to form Re-NLS and Re-Bombesin, respectively. Fluorescent microscopy on cervical cancer cells (HeLa) showed that the conjugation of Re-COOH to NLS significantly enhanced the compound's accumulation into the cell nucleus and more specifically into its nucleoli. Importantly, in view of PDT applications, the cytotoxicity of the Re complexes and their bioconjugates increased significantly upon light irradiation. In particular, Re-Bombesin was found to be at least 20-fold more toxic after light irradiation. DNA photo-cleavage studies demonstrated that all compounds damaged DNA via singlet oxygen and, to a minor extent, superoxide production.

  1. The organometallic fluorine chemistry of palladium and rhodium: studies toward aromatic fluorination.

    PubMed

    Grushin, Vladimir V

    2010-01-19

    Although springing from two established fields, organometallic chemistry and fluorine chemistry, organometallic fluorine chemistry is still in its early stages. However, developments in this area are expected to provide new tools for the synthesis of selectively fluorinated organic compounds that have been in high demand. Selectively fluorinated organic molecules currently account for up to 40% of all agrochemicals and 20% of all pharmaceuticals on the market. Our research efforts have been focused on the development of new organometallic and catalytic methods for the selective introduction of fluorine and the CF(3) group into the aromatic ring. Monofluorinated and trifluoromethylated aromatic compounds are still made by the old technologies that employ stoichiometric quantities of hazardous and costly materials. In this Account, we describe our studies toward the development of safe, catalytic alternatives to these methods. We have synthesized, characterized, and studied the reactivity of the first aryl palladium(II) fluoride complexes. We have demonstrated for the first time that a Pd-F bond can be formed in a soluble and isolable molecular complex: this bond is more stable than previously thought. Toward the goal of fluoroarene formation via Ar-F reductive elimination, we have studied a number of sigma-aryl Pd(II) fluorides stabilized by various P, N, and S ligands. It has been established that numerous conventional tertiary phosphine ligands, most popular in Pd catalysis, are unlikely to be useful for the desired C-F bond formation at the metal center because of the competing, kinetically preferred P-F bond-forming reaction. A metallophosphorane mechanism has been demonstrated for the P-F bond-forming processes at Rh(I) and Pd(II), which rules out the possibility of controlling these reactions by varying the amount of phosphine in the system, a most common and often highly efficient technique in homogeneous catalysis. The novel F/Ph rearrangement of the fluoro

  2. Aqueous phase reforming of glycerol over Ni-based catalysts for hydrogen production.

    PubMed

    Cho, Su Hyun; Moon, Dong Ju

    2011-08-01

    Aqueous phase reforming of glycerol over Ni-based catalysts for hydrogen production was carried out at 225 degrees C, 23 bar and LHSV = 4 h(-1). The Ni-based catalyst was prepared by an incipient wetness impregnation method. The catalysts before and after the reaction were characterized by N2 physisorption, CO chemisorption, XRD, TPR, SEM and TEM techniques. It was found that Ni(20 wt%)-Co(3 wt%)/gamma-Al2O3 catalyst showed higher glycerol conversion and hydrogen selectivity than Ni(20 wt%)/gamma-Al2O3 catalyst. There are no major changes in Ni particles after the reaction over Ni-Co/gamma-Al2O3 catalyst. The results suggest that the Ni-Co/gamma-Al2O3 catalyst can be applied to the hydrogen production system using APR of glycerol.

  3. Estimation of conjugate gamma and gamma-prime compositions in Ni-base superalloys

    NASA Technical Reports Server (NTRS)

    Dreshfield, R. L.

    1977-01-01

    To control the formation of unwanted phases, superalloy metallurgists have developed methods of estimating the composition of the matrix phase of alloys. That composition is then used to estimate the alloy's propensity toward sigma and other unwanted phase formations upon prolonged exposure to elevated temperatures in service. This paper reviews two approaches for estimating phase composition from the melt composition. One method is based on assigning essentially fixed stoichiometry to precipitating phases and is typified by 'PHACOMP'. The second method uses analytical geometry to interpret phase diagrams and is shown to be applicable to a two-phase region of a six-component Ni-base system. The geometric method is also shown to be applicable to commercial Ni-base superalloys.

  4. Simulation of γ' Precipitation Kinetics in a Commercial Ni-Base Superalloy

    NASA Astrophysics Data System (ADS)

    Fahrmann, M. G.; Metzler, D. A.

    2016-11-01

    The ability to accurately simulate the precipitation kinetics of γ' and other strengthening phases in Ni-base superalloys is of great interest to industry. Several commercial simulation tools such as TC-PRISMA (Thermo-Calc, Sweden) and PanPrecipitation (Computherm, USA) have been made available in recent years. This paper reports the outcome of a validation study on wrought Ni-base superalloy HAYNES® 282® alloy for two scenarios of commercial interest: (1) the precipitation of γ' during continuous cooling, and (2) the precipitation of γ' during two-step aging. The simulation results are validated against experimental data. Any discrepancies are discussed in the context of the uncertainty in key material properties (such as interfacial energies), model assumptions, and experimental errors.

  5. A synchrotron study of microstructure gradient in laser additively formed epitaxial Ni-based superalloy

    PubMed Central

    Xue, Jiawei; Zhang, Anfeng; Li, Yao; Qian, Dan; Wan, Jingchun; Qi, Baolu; Tamura, Nobumichi; Song, Zhongxiao; Chen, Kai

    2015-01-01

    Laser additive forming is considered to be one of the promising techniques to repair single crystal Ni-based superalloy parts to extend their life and reduce the cost. Preservation of the single crystalline nature and prevention of thermal mechanical failure are two of the most essential issues for the application of this technique. Here we employ synchrotron X-ray microdiffraction to evaluate the quality in terms of crystal orientation and defect distribution of a Ni-based superalloy DZ125L directly formed by a laser additive process rooted from a single crystalline substrate of the same material. We show that a disorientation gradient caused by a high density of geometrically necessary dislocations and resultant subgrains exists in the interfacial region between the epitaxial and stray grains. This creates a potential relationship of stray grain formation and defect accumulation. The observation offers new directions on the study of performance control and reliability of the laser additive manufactured superalloys. PMID:26446425

  6. A synchrotron study of microstructure gradient in laser additively formed epitaxial Ni-based superalloy

    SciTech Connect

    Xue, Jiawei; Zhang, Anfeng; Li, Yao; Qian, Dan; Wan, Jingchun; Qi, Baolu; Tamura, Nobumichi; Song, Zhongxiao; Chen, Kai

    2015-10-08

    Laser additive forming is considered to be one of the promising techniques to repair single crystal Ni-based superalloy parts to extend their life and reduce the cost. Preservation of the single crystalline nature and prevention of thermal mechanical failure are two of the most essential issues for the application of this technique. Here we employ synchrotron X-ray microdiffraction to evaluate the quality in terms of crystal orientation and defect distribution of a Ni-based superalloy DZ125L directly formed by a laser additive process rooted from a single crystalline substrate of the same material. We show that a disorientation gradient caused by a high density of geometrically necessary dislocations and resultant subgrains exists in the interfacial region between the epitaxial and stray grains. This creates a potential relationship of stray grain formation and defect accumulation. In conclusion, the observation offers new directions on the study of performance control and reliability of the laser additive manufactured superalloys.

  7. Microstructural Evolution During Friction Stir Welding of Mild Steel and Ni-Based Alloy 625

    NASA Astrophysics Data System (ADS)

    Fernandez, Johnnatan Rodriguez; Ramirez, Antonio J.

    2017-01-01

    Microstructure evolution during friction stir welding (FSW) of mild steel and Ni-based alloy 625 was studied. Regarding the Ni-based alloy, the welding process led to grain refinement caused by discontinuous and continuous dynamic recrystallization, where bulging of the pre-existing grains and subgrain rotation were the primary mechanisms of recrystallization. In the steel, discontinuous dynamic recrystallization was identified as the recovery process experienced by the austenite. Simple shear textures were observed in the regions affected by the deformation of both materials. Although the allotropic transformation obscured the deformation history, the thermo-mechanically affected zone was identified in the steel by simple shear texture components. A new methodology for the study of texture evolution based on rotations of the slip systems using pole figures is presented as an approximation to describe the texture evolution in FSW.

  8. Microstructural Evolution During Friction Stir Welding of Mild Steel and Ni-Based Alloy 625

    NASA Astrophysics Data System (ADS)

    Fernandez, Johnnatan Rodriguez; Ramirez, Antonio J.

    2017-03-01

    Microstructure evolution during friction stir welding (FSW) of mild steel and Ni-based alloy 625 was studied. Regarding the Ni-based alloy, the welding process led to grain refinement caused by discontinuous and continuous dynamic recrystallization, where bulging of the pre-existing grains and subgrain rotation were the primary mechanisms of recrystallization. In the steel, discontinuous dynamic recrystallization was identified as the recovery process experienced by the austenite. Simple shear textures were observed in the regions affected by the deformation of both materials. Although the allotropic transformation obscured the deformation history, the thermo-mechanically affected zone was identified in the steel by simple shear texture components. A new methodology for the study of texture evolution based on rotations of the slip systems using pole figures is presented as an approximation to describe the texture evolution in FSW.

  9. Oxidation Resistance: One Barrier to Moving Beyond Ni-Base Superalloys

    SciTech Connect

    Pint, Bruce A; Distefano, James R; Wright, Ian G

    2006-01-01

    The implementation of new high-temperature materials is often hampered by their lack of oxidation or environmental resistance. This failing is one of the strongest barriers to moving beyond Ni-base superalloys for many commercial applications. In practice, usable high-temperature alloys have at least reasonable oxidation resistance, but the current generation of single-crystal Ni-base superalloys has sufficient oxidation resistance that optimized versions can be used without a metallic bond coating and only an oxygen-transparent ceramic coating for thermal protection. The material development process often centers around mechanical properties, while oxidation resistance, along with other realities, is given minor attention. For many applications, the assumption that an oxidation-resistant coating can be used to protect a substrate is seriously flawed, as coatings often do not provide sufficient reliability for critical components. Examples of oxidation problems are given for currently used materials and materials classes with critical oxidation resistance problems.

  10. Organometallic complexes with terminal imidazolato ligands and their use as metalloligands.

    PubMed

    Gómez, Eva; Huertos, Miguel A; Pérez, Julio; Riera, Lucía; Menéndez-Velázquez, Amador

    2010-10-18

    Compounds [Re(bipy)(CO)(3)(HIm)]OTf (1) and [Mo(η(3)-C(3)H(4)-R-2)(CO)(2)(HIm)(phen)]BAr'(4) [R = Me (2a), H (2b); Ar' = 3,5-bis(trifluoromethyl)phenyl; HIm = 1H-imidazole] were prepared from 1H-imidazole and either [Re(OTf)(bipy)(CO)(3)] or [MoCl(η(3)-C(3)H(4)-R-2)(CO)(2)(phen)]. Compounds 1, 2a, and 2b were deprotonated to afford the terminal κ-N-imidazolate complexes [Re(bipy)(CO)(3)(Im)] (3) and [Mo(η(3)-C(3)H(4)-R-2)(CO)(2)(Im)(phen)] [R = Me (4a), H (4b)], which were fully characterized, including an X-ray structural determination of 3. The topological analysis of the electron density (obtained from the X-ray diffraction study) and its Laplacian were used to characterize the differences in the electron density at the five-membered ring ligand between the imidazole and imidazolate complexes 1 and 3. The reaction of complexes 3, 4a, and 4b with the appropriate organometallic complexes afforded the bimetallic imidazolate-bridged compounds [{Re(bipy)(CO)(3)}(2)(μ-Im)]OTf (5), [{Mo(η(3)-C(4)H(7))(CO)(2)(phen)}(2)(μ-Im)]OTf (6), and [{Mo(η(3)-C(3)H(5))(CO)(2)(phen)}(μ-Im){Re(phen)(CO)(3)}]OTf (7). The reaction of [Mo(η(3)-C(4)H(7))(CO)(2)(Im)(phen)] (4a) with SnClPh(3) led to the formation of the trinuclear complex [{Mo(η(3)-C(4)H(7))(CO)(2)(phen)(μ-Im)}(2){SnPh(3)}]BAr'(4) (8).

  11. The state and catalytic properties of (Ni + Pd)/SiO{sub 2} systems obtained by grafting organometallic complexes on the surface of SiO{sub 2}

    SciTech Connect

    Koval`chuk, V.I.; Chesnokov, N.V.; Naimushina, L.V.

    1995-05-01

    The adsorption and catalytic properties of Pd/SiO{sub 2}, Ni/SiO{sub 2}, and (Pd + Ni)/SiO{sub 2} samples obtained by grafting organometallic Pd and Ni compounds on the support surface are studied. Bimetallic Pd-Ni catalysts are shown to have an additive catalytic action in the hydrogenation of benzene. Synergistic effects are detected in the reactions of ethane hydrogenolysis, CO hydrogenation, and propylene hydroformylation. The obtained data show that the surface of bimetallic cluster particles becomes enriched with palladium atoms.

  12. Effect of organometallic fuel additives on nanoparticle emissions from a gasoline passenger car.

    PubMed

    Gidney, Jeremy T; Twigg, Martyn V; Kittelson, David B

    2010-04-01

    Particle size measurements were performed on the exhaust of a car operating on a chassis dynamometer fueled with standard gasoline and gasoline containing low levels of Pb, Fe, and Mn organometallic additives. When additives were present there was a distinct nucleation mode consisting primarily of sub-10 nm nanoparticles. At equal molar dosing Mn and Fe gave similar nanoparticle concentrations at the tailpipe, whereas Pb gave a considerably lower concentration. A catalytic stripper was used to remove the organic component of these particles and revealed that they were mainly solid and, because of their association with inorganic additives, presumably inorganic. Solid nucleation mode nanoparticles of similar size and concentration to those observed here from a gasoline engine with Mn and Fe additives have also been observed from modern heavy-duty diesel engines without aftertreatment at idle, but these solid particles are a small fraction of the primarily volatile nucleation mode particles emitted. The solid nucleation mode particles emitted by the diesel engines are likely derived from metal compounds in the lubrication oil, although carbonaceous particles cannot be ruled out. Significantly, most of these solid nanoparticles emitted by both engine types fall below the 23 nm cutoff of the PMP number regulation.

  13. Selective Organic and Organometallic Reactions in Water-Soluble Host-Guest Supramolecular Systems

    SciTech Connect

    Pluth, Michael D.; Raymond, Kenneth N.; Bergman, Robert G.

    2008-02-16

    Inspired by the efficiency and selectivity of enzymes, synthetic chemists have designed and prepared a wide range of host molecules that can bind smaller molecules with their cavities; this area has become known as 'supramolecular' or 'host-guest' chemistry. Pioneered by Lehn, Cram, Pedersen, and Breslow, and followed up by a large number of more recent investigators, it has been found that the chemical environment in each assembly - defined by the size, shape, charge, and functional group availability - greatly influences the guest-binding characteristics of these compounds. In contrast to the large number of binding studies that have been carried out in this area, the exploration of chemistry - especially catalytic chemistry - that can take place inside supramolecular host cavities is still in its infancy. For example, until the work described here was carried out, very few examples of organometallic reactivity inside supramolecular hosts were known, especially in water solution. For that reason, our group and the group directed by Kenneth Raymond decided to take advantage of our complementary expertise and attempt to carry out metal-mediated C-H bond activation reactions in water-soluble supramolecular systems. This article begins by providing background from the Raymond group in supramolecular coordination chemistry and the Bergman group in C-H bond activation. It goes on to report the results of our combined efforts in supramolecular C-H activation reactions, followed by extensions of this work into a wider range of intracavity transformations.

  14. Chromocene in porous polystyrene: an example of organometallic chemistry in confined spaces.

    PubMed

    Estephane, Jane; Groppo, Elena; Vitillo, Jenny G; Damin, Alessandro; Lamberti, Carlo; Bordiga, Silvia; Zecchina, Adriano

    2009-04-07

    In this work, we present an innovative approach to investigate the structure and the reactivity of a molecularly dispersed organometallic compound. The poly(4-ethylstyrene-co-divinylbenzene) microporous system (PS) is used as "solid solvent" able to molecularly disperse CrCp2, allowing: (i) its full characterization by means of spectroscopic techniques; (ii) the pressure and temperature dependent study of its interaction towards simple molecules like CO freely diffusing through the pores; (iii) the accurate determination of the reaction enthalpies by both direct microcalorimetric measurements and by an indirect spectroscopic approach. The experimental results are compared with quantum-mechanical calculations adopting the DFT approximation with two different functionals (namely BP86 and B3-LYP), showing the limitations and the potentialities of DFT methods in predicting the properties of open shell systems. It is concluded that modern DFT methods are able to give a coherent view of the vibrational properties of the CrCp2 molecule (and of the complex formed upon CO adsorption) that well match the experimental results, while the energetic predictions should be taken with care as they are significantly dependent on the functionals used.

  15. Organometallic Rhenium Complexes Divert Doxorubicin to the Mitochondria.

    PubMed

    Imstepf, Sebastian; Pierroz, Vanessa; Rubbiani, Riccardo; Felber, Michael; Fox, Thomas; Gasser, Gilles; Alberto, Roger

    2016-02-18

    Doxorubicin, a well-established chemotherapeutic agent, is known to accumulate in the cell nucleus. By using ICP-MS, we show that the conjugation of two small organometallic rhenium complexes to this structural motif results in a significant redirection of the conjugates from the nucleus to the mitochondria. Despite this relocation, the two bioconjugates display excellent toxicity toward HeLa cells. In addition, we carried out a preliminarily investigation of aspects of cytotoxicity and present evidence that the conjugates disrupt the mitochondrial membrane potential, are strong inhibitors of human Topoisomerase II, and induce apoptosis. Such derivatives may enhance the therapeutic index of the aggressive parent drug and overcome drug resistance by influencing nuclear and mitochondrial homeostasis.

  16. Naturally Efficient Emitters: Luminescent Organometallic Complexes Derived from Natural Products

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Hua; Young, David J.

    2013-08-01

    Naturally occurring molecules offer intricate structures and functionality that are the basis of modern medicinal chemistry, but are under-represented in materials science. Herein, we review recent literature describing the use of abundant and relatively inexpensive, natural products for the synthesis of ligands for luminescent organometallic complexes used for organic light emitting diodes (OLEDs) and related technologies. These ligands are prepared from the renewable starting materials caffeine, camphor, pinene and cinchonine and, with the exception of caffeine, impart performance improvements to the emissive metal complexes and resulting OLED devices, with emission wavelengths that span the visible spectrum from blue to red. The advantages of these biologically-derived molecules include improved solution processibility and phase homogeneity, brighter luminescence, higher quantum efficiencies and lower turn-on voltages. While nature has evolved these carbon-skeletons for specific purposes, they also offer some intriguing benefits in materials science and technology.

  17. Flat Chern Band in a Two-Dimensional Organometallic Framework

    NASA Astrophysics Data System (ADS)

    Liu, Zheng; Wang, Zheng-Fei; Mei, Jia-Wei; Wu, Yong-Shi; Liu, Feng

    2013-03-01

    By combining exotic band dispersion with nontrivial band topology, an interesting type of band, namely the flat chern band (FCB), has recently been proposed, in which carriers experience strong Coulomb interaction as well as topological frustration that in together spawn unprecedented topological strongly-correlated electronic states, such as high-temperature fractional quantum hall state. Despite the proposal of several theoretical lattice models, however, it remains a doubt whether such a ``romance of flatland'' could exist in a real material. Here, we present a first-principles design to realize a nearly FCB right around the Fermi level in a two-dimensional (2D) Indium-Phenylene Organometallic Framework (IPOF). Our design in addition provides a general strategy to synthesize topologically nontrivial materials in virtue of organic chemistry and nanotechnology. Supported by DOE-BES and ARL

  18. Flat Chern Band in a Two-Dimensional Organometallic Framework

    NASA Astrophysics Data System (ADS)

    Liu, Zheng; Wang, Zheng-Fei; Mei, Jia-Wei; Wu, Yong-Shi; Liu, Feng

    2013-03-01

    By combining exotic band dispersion with nontrivial band topology, an interesting type of band structure, namely, the flat Chern band, has recently been proposed to spawn high-temperature fractional quantum Hall states. Despite the proposal of several theoretical lattice models, however, it remains doubtful whether such a “romance of flatland” could exist in a real material. Here, we present a first-principles design of a two-dimensional indium-phenylene organometallic framework that realizes a nearly flat Chern band right around the Fermi level by combining lattice geometry, spin-orbit coupling, and ferromagnetism. An effective four-band model is constructed to reproduce the first-principles results. Our design, in addition, provides a general strategy to synthesize topologically nontrivial materials by virtue of organic chemistry and nanotechnology.

  19. Hydroconversion of heavy crude oils using soluble metallic compounds in the presence of hydrogen or methane

    SciTech Connect

    Morales, A.; Salazar, A.; Ovalles, C.; Filgueiras, E.

    1996-12-31

    The hydroconversion of heavy crude oil was studied under thermal and catalytic conditions using soluble organo-metallic compounds of Mo, Fe, Cr, V, Ni, and Co as a catalyst precursors. All catalysts are effective for the hydroconversion, however, molybdenum and nickel compounds are preferred.

  20. Organometallic catalysts for primary phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Walsh, Fraser

    1987-01-01

    A continuing effort by the U.S. Department of Energy to improve the competitiveness of the phosphoric acid fuel cell by improving cell performance and/or reducing cell cost is discussed. Cathode improvement, both in performance and cost, available through the use of a class of organometallic cathode catalysts, the tetraazaannulenes (TAAs), was investigated. A new mixed catalyst was identified which provides improved cathode performance without the need for the use of a noble metal. This mixed catalyst was tested under load for 1000 hr. in full cell at 160 to 200 C in phosphoric acid H3PO4, and was shown to provide stable performance. The mixed catalyst contains an organometallic to catalyze electroreduction of oxygen to hydrogen peroxide and a metal to catalyze further electroreduction of the hydrogen peroxide to water. Cathodes containing an exemplar mixed catalyst (e.g., Co bisphenyl TAA/Mn) operate at approximately 650 mV vs DHE in 160 C, 85% H3PO4 with oxygen as reactant. In developing this mixed catalyst, a broad spectrum of TAAs were prepared, tested in half-cell and in a rotating ring-disk electrode system. TAAs found to facilitate the production of hydrogen peroxide in electroreduction were shown to be preferred TAAs for use in the mixed catalyst. Manganese (Mn) was identified as a preferred metal because it is capable of catalyzing hydrogen peroxide electroreduction, is lower in cost and is of less strategic importance than platinum, the cathode catalyst normally used in the fuel cell.

  1. Organometallic catalysts for primary phosphoric acid fuel cells

    NASA Astrophysics Data System (ADS)

    Walsh, Fraser

    1987-03-01

    A continuing effort by the U.S. Department of Energy to improve the competitiveness of the phosphoric acid fuel cell by improving cell performance and/or reducing cell cost is discussed. Cathode improvement, both in performance and cost, available through the use of a class of organometallic cathode catalysts, the tetraazaannulenes (TAAs), was investigated. A new mixed catalyst was identified which provides improved cathode performance without the need for the use of a noble metal. This mixed catalyst was tested under load for 1000 hr. in full cell at 160 to 200 C in phosphoric acid H3PO4, and was shown to provide stable performance. The mixed catalyst contains an organometallic to catalyze electroreduction of oxygen to hydrogen peroxide and a metal to catalyze further electroreduction of the hydrogen peroxide to water. Cathodes containing an exemplar mixed catalyst (e.g., Co bisphenyl TAA/Mn) operate at approximately 650 mV vs DHE in 160 C, 85% H3PO4 with oxygen as reactant. In developing this mixed catalyst, a broad spectrum of TAAs were prepared, tested in half-cell and in a rotating ring-disk electrode system. TAAs found to facilitate the production of hydrogen peroxide in electroreduction were shown to be preferred TAAs for use in the mixed catalyst. Manganese (Mn) was identified as a preferred metal because it is capable of catalyzing hydrogen peroxide electroreduction, is lower in cost and is of less strategic importance than platinum, the cathode catalyst normally used in the fuel cell.

  2. Microstructural Stability and Hot Deformation of γ- γ'- δ Ni-Base Superalloys

    NASA Astrophysics Data System (ADS)

    Detrois, Martin; Helmink, Randolph C.; Tin, Sammy

    2014-11-01

    Nickel-base superalloys exhibit excellent high-temperature mechanical and physical properties and remain the first choice for structural components in advanced gas turbine engines for the aerospace propulsion and power generation applications. In response to the increasing demand for more efficient solutions and tighter requirements linked to gas turbine technologies, the properties of nickel-base superalloys can be improved by modification of their thermo-mechanical and/or compositional attributes. Recent investigations have revealed the potential use of ternary eutectic γ- γ'- δ Ni-base superalloys in advanced gas turbines due to high temperature mechanical properties that are comparable to state-of-the-art polycrystalline Ni-base superalloys. With properties largely dependent on microstructural strengthening mechanisms, both the composition and thermo-mechanical processing parameters of this novel class of alloys need to be optimized concurrently. The hot deformation characteristics of four γ- γ'- δ Ni-base superalloys with varying levels of Nb were evaluated at temperatures and strain rates between 1353 K and 1433 K (1080 °C and 1160 °C) and 0.01 to 0.001/s, respectively. Evidence of dislocation-based plasticity was observed following deformation at low temperatures and high strain rates, while high temperatures and low strain rates promoted superplasticity in these alloys. The extent of the microstructural changes and the magnitude of the cavitation damage which occurred during deformation was found to vary as a function of the alloy composition.

  3. Organometallic acetylides of Pt(II), Au(I) and Hg(II) as new generation optical power limiting materials.

    PubMed

    Zhou, Gui-Jiang; Wong, Wai-Yeung

    2011-05-01

    Within the scope of nonlinear optics, optical power limiting (OPL) materials are commonly regarded as an important class of compounds which can protect the delicate optical sensors or human eyes from sudden exposure to damaging intense laser beams. Recent efforts have been devoted to developing organometallic acetylide complexes, dendrimers and polymers as high performance OPL materials of the next generation which can favorably optimize the optical limiting/transparency trade-off issue. These metallated materials offer a new avenue towards a new family of highly transparent homo- and heterometallic optical limiters with good solution processability which outperform those of current state-of-the-art visible-light-absorbing competitors such as fullerenes, metalloporphyrins and metallophthalocyanines. This critical review aims to provide a detailed account on the recent advances of these novel OPL chromophores. Their OPL activity was shown to depend strongly on the electronic characters of the aryleneethynylene ligand and transition metal moieties as well as the conjugation chain length of the compounds. Strategies including copolymerization with other transition metals, change of structural geometry, use of a dendritic platform and variation of the type and content of transition metal ions would strongly govern their photophysical behavior and improve the resulting OPL responses. Special emphasis is placed on the structure-OPL response relationships of these organometallic acetylide materials. The research endeavors for realizing practical OPL devices based on these materials have also been presented. This article concludes with perspectives on the current status of the field, as well as opportunities that lie just beyond its frontier (106 references).

  4. Effect of fuel gas composition in chemical-looping combustion with Ni-based oxygen carriers. 1. Fate of sulfur

    SciTech Connect

    Garcia-Labiano, F.; de Diego, L.F.; Gayan, P.; Adanez, J.; Abad, A.; Dueso, C.

    2009-03-15

    Chemical-looping combustion (CLC) has been suggested among the best alternatives to reduce the economic cost of CO{sub 2} capture using fuel gas because CO{sub 2} is inherently separated in the process. For gaseous fuels, natural gas, refinery gas, or syngas from coal gasification can be used. These fuels may contain different amounts of sulfur compounds, such as H{sub 2}S and COS. An experimental investigation of the fate of sulfur during CH{sub 4} combustion in a 500 W{sub th} CLC prototype using a Ni-based oxygen carrier has been carried out. The effect on the oxygen carrier behavior and combustion efficiency of several operating conditions such as temperature and H{sub 2}S concentration has been analyzed. Nickel sulfide, Ni3S{sub 2}, was formed at all operating conditions in the fuel reactor, which produced an oxygen carrier deactivation and lower combustion efficiencies. However, the oxygen carrier recovered their initial reactivity after certain time without sulfur addition. The sulfides were transported to the air reactor where SO{sub 2} was produced as final gas product. Agglomeration problems derived from the sulfides formation were never detected during continuous operation. Considering both operational and environmental aspects, fuels with sulfur contents below 100 vppm H{sub 2}S seem to be adequate to be used in an industrial CLC plant.

  5. Tribromobenzene on Cu(111): Temperature-dependent formation of halogen-bonded, organometallic, and covalent nanostructures

    SciTech Connect

    Fan, Qitang; Wang, Tao; Zhu, Junfa; Liu, Liming; Zhao, Jin; Gottfried, J. Michael

    2015-03-14

    The temperature-controlled surface-assisted synthesis of halogen bonded, organometallic, and covalent nanostructures based on 1,3,5-tribromo-benzene (TriBB) was studied with scanning tunneling microscopy and X-ray photoemission spectroscopy in ultrahigh vacuum. Vapor deposition of TriBB onto a Cu(111) surface held at 90 K leads to the formation of large domains of a honeycomb-like organic monolayer structure stabilized by triangular nodes with Br⋯Br intermolecular bonds. Upon annealing the organic monolayer to ∼140 K, a new hexagonal close-packed structure with intact TriBB molecules connected by Cu adatoms is formed. Further warming up the sample to 300 K gives rise to the scission of C–Br bonds and formation of C–Cu–C bonds between phenyl fragments such that stable dendritic organometallic networks are formed. Larger islands of organometallic networks are obtained by maintaining the temperature of Cu(111) at 420 K during deposition of TriBB. Simultaneously, large islands of Br atoms are formed around the organometallic networks. Annealing the more extended organometallic network (prepared at 420 K) to 520 K leads to the formation of a branched covalent organic framework (COF) which comprises structural elements of porous graphene and is surrounded by Br islands. These organometallic networks and COFs appear as small dendritic and branched domains, most likely due to the steric influence exerted by the Br islands.

  6. Tribromobenzene on Cu(111): Temperature-dependent formation of halogen-bonded, organometallic, and covalent nanostructures

    NASA Astrophysics Data System (ADS)

    Fan, Qitang; Wang, Tao; Liu, Liming; Zhao, Jin; Zhu, Junfa; Gottfried, J. Michael

    2015-03-01

    The temperature-controlled surface-assisted synthesis of halogen bonded, organometallic, and covalent nanostructures based on 1,3,5-tribromo-benzene (TriBB) was studied with scanning tunneling microscopy and X-ray photoemission spectroscopy in ultrahigh vacuum. Vapor deposition of TriBB onto a Cu(111) surface held at 90 K leads to the formation of large domains of a honeycomb-like organic monolayer structure stabilized by triangular nodes with Br⋯Br intermolecular bonds. Upon annealing the organic monolayer to ˜140 K, a new hexagonal close-packed structure with intact TriBB molecules connected by Cu adatoms is formed. Further warming up the sample to 300 K gives rise to the scission of C-Br bonds and formation of C-Cu-C bonds between phenyl fragments such that stable dendritic organometallic networks are formed. Larger islands of organometallic networks are obtained by maintaining the temperature of Cu(111) at 420 K during deposition of TriBB. Simultaneously, large islands of Br atoms are formed around the organometallic networks. Annealing the more extended organometallic network (prepared at 420 K) to 520 K leads to the formation of a branched covalent organic framework (COF) which comprises structural elements of porous graphene and is surrounded by Br islands. These organometallic networks and COFs appear as small dendritic and branched domains, most likely due to the steric influence exerted by the Br islands.

  7. The first organometallic selective estrogen receptor modulators (SERMs) and their relevance to breast cancer.

    PubMed

    Jaouen, Gérard; Top, Siden; Vessières, Anne; Leclercq, G; McGlinchey, Michael J

    2004-09-01

    In the overall scheme of the future development of new drugs for the treatment of breast cancer, specially tamoxifen resistant tumours, we have explored the unprecedented use of organometallic SERMs. The initial idea is to enhance the efficacy of the current standard, i.e. tamoxifen, by modifying the structure through judicious incorporation of an organometallic moiety possessing novel properties. Results have been varied, justifying a systematic approach that has proved to be full of surprised. The following differing situations were observed (a) the anti-proliferative effect is due to the vector and the organometallic moiety does not improve the effects of the SERM, no matter what concentration is used. In particular, this is the case for the hydroxytamoxifen derivative bearing a CpRe(CO)3 group, which behaves almost identically to hydroxytamoxifen. These stable species have future promise for use with radionucleides of Re and Tc (b) the effect of the organometallic moiety counteracts the anti-estrogenic behaviour of the vector and leads to species with proliferative activity; this is the case with Cp2TiCl2 entity, which when attached to tamoxifen behaves as a powerful estrogen, probably due to in situ release of Ti(IV) (c) a synergy exists between the cytotoxic organometallic moiety and its organic vector, leading to unique anti-proliferative effects on breast cancer cells classed ER+ and ER-. This result opens a new window on organometallic oncology. It is also clear that the range of possibilities is broad, varied and currently unpredictable. A systematic study combining organometallic chemistry and biology is the only option in the search for new SERMs with novel properties.

  8. Potential and limitations of microanalysis SEM techniques to characterize borides in brazed Ni-based superalloys

    SciTech Connect

    Ruiz-Vargas, J.; Siredey-Schwaller, N.; Noyrez, P.; Mathieu, S.; Bocher, P.; and others

    2014-08-15

    Brazed Ni-based superalloys containing complex phases of different Boron contents remain difficult to characterize at the micrometer scale. Indeed Boron is a light element difficult to measure precisely. The state-of-the-art microanalysis systems have been tested on a single crystal MC2 based metal brazed with BNi-2 alloy to identify boride precipitates. Effort has been made to evaluate the accuracy in Boron quantitation. Energy-dispersive and wavelength-dispersive X-ray spectroscopy attached to a Scanning Electron Microscope have first been used to determine the elemental composition of Boron-free phases, and then applied to various types of borides. Results have been compared to the ones obtained using a dedicated electron probe microanalysis, considered here as the reference technique. The most accurate method to quantify Boron using EDS is definitely by composition difference. A precision of 5 at.% could be achieved with optimized data acquisition and post-processing schemes. Attempts that aimed at directly quantifying Boron with various standards using EDS or coupled EDS/WDS gave less accurate results. Ultimately, Electron Backscatter Diffraction combined with localized EDS analysis has proved invaluable in conclusively identifying micrometer sized boride precipitates; thus further improving the characterization of brazed Ni-based superalloys. - Highlights: • We attempt to accurately identify Boron-rich phases in Ni-based superalloys. • EDS, WDS, EBSD systems are tested for accurate identification of these borides. • Results are compared with those obtained by electron probe microanalysis. • Boron was measured with EDS by composition difference with a precision of 5 at. %. • Additional EBSD in phase identification mode conclusively identifies the borides.

  9. Oxidation Resistance of Low-Temperature Pack Aluminizing Coatings on Ni-Base Superalloy

    NASA Astrophysics Data System (ADS)

    Yuan, Bifei; Yu, Longwen; Lu, Guiwu

    A nickel-base superalloy has been used to deposit the aluminide coating by low-temperature pack cementation process. The high temperature oxidation tests on aluminized alloys and the uncoated specimens are carried out at 1000°C for 10h. It is observed that a dense and protective Al2O3 surface layer is produced on the aluminized alloy, and the aluminizing process has greatly enhanced the high temperature oxidation resistance of the Ni-base superalloy at 1000°C. As a contrast, the uncoated specimen begins to be failure when treated only for 6h at the same temperature.

  10. Microscopic study of the structure of the Steel Ni-based Alloy: Hastelloy G35 Alloy

    NASA Astrophysics Data System (ADS)

    Sabir, F.; Ben Lenda, O.; Saissi, S.; Marbouh, K.; Tyouke, B.; Zerrouk, L.; Ibnlfassi, A.; Ouzaouit, K.; Elmadani, S.

    2017-03-01

    The study of the influence of heat treatment on changes of mechanical and structural properties of Steel Ni-based Alloy is a highly interdisciplinary topic at the interface of the physical chemistry of metallic materials, which also helps in environmental and economic protection.After heat treatment, the structural and micro-structural studies for the different transformation temperature led to identify phases formed and the morphology. This work has been carried out using different techniques: X-ray diffraction, optical microscopy and scanning electron microscopy.

  11. Mesoscale modeling and simulation of microstructure evolution during dynamic recrystallization of a Ni-based superalloy

    NASA Astrophysics Data System (ADS)

    Chen, Fei; Cui, Zhenshan; Ou, Hengan; Long, Hui

    2016-10-01

    Microstructural evolution and plastic flow characteristics of a Ni-based superalloy were investigated using a simulative model that couples the basic metallurgical principle of dynamic recrystallization (DRX) with the two-dimensional (2D) cellular automaton (CA). Variation of dislocation density with local strain of deformation is considered for accurate determination of the microstructural evolution during DRX. The grain topography, the grain size and the recrystallized fraction can be well predicted by using the developed CA model, which enables to the establishment of the relationship between the flow stress, dislocation density, recrystallized fraction volume, recrystallized grain size and the thermomechanical parameters.

  12. Deciphering Halogen Competition in Organometallic Halide Perovskite Growth

    DOE PAGES

    Keum, Jong Kahk; Ovchinnikova, Olga S.; Chen, Shiyou; ...

    2016-03-01

    Organometallic halide perovskites (OHPs) hold great promise for next-generation, low-cost optoelectronic devices. During the chemical synthesis and crystallization of OHP thin films a major unresolved question is the competition between multiple halide species (e.g. I-, Cl-, Br-) in the formation of the mixed halide perovskite crystals. Whether Cl- ions are successfully incorporated into the perovskite crystal structure or alternatively, where they are located, is not yet fully understood. Here, in situ X-ray diffraction measurements of crystallization dynamics are combined with ex situ TOF-SIMS chemical analysis to reveal that Br- or Cl- ions can promote crystal growth, yet reactive I- ionsmore » prevent them from incorporating into the lattice of the final perovskite crystal structure. The Cl- ions are located in the grain boundaries of the perovskite films. These findings significantly advance our understanding of the role of halogens during synthesis of hybrid perovskites, and provide an insightful guidance to the engineering of high-quality perovskite films, essential for exploring superior-performance and cost-effective optoelectronic devices.« less

  13. Deciphering Halogen Competition in Organometallic Halide Perovskite Growth

    SciTech Connect

    Keum, Jong Kahk; Ovchinnikova, Olga S.; Chen, Shiyou; Du, Mao-Hua; Ivanov, Ilia N; Rouleau, Christopher; Geohegan, David B.; Xiao, Kai

    2016-03-01

    Organometallic halide perovskites (OHPs) hold great promise for next-generation, low-cost optoelectronic devices. During the chemical synthesis and crystallization of OHP thin films a major unresolved question is the competition between multiple halide species (e.g. I-, Cl-, Br-) in the formation of the mixed halide perovskite crystals. Whether Cl- ions are successfully incorporated into the perovskite crystal structure or alternatively, where they are located, is not yet fully understood. Here, in situ X-ray diffraction measurements of crystallization dynamics are combined with ex situ TOF-SIMS chemical analysis to reveal that Br- or Cl- ions can promote crystal growth, yet reactive I- ions prevent them from incorporating into the lattice of the final perovskite crystal structure. The Cl- ions are located in the grain boundaries of the perovskite films. These findings significantly advance our understanding of the role of halogens during synthesis of hybrid perovskites, and provide an insightful guidance to the engineering of high-quality perovskite films, essential for exploring superior-performance and cost-effective optoelectronic devices.

  14. Sweetening ruthenium and osmium: organometallic arene complexes containing aspartame.

    PubMed

    Gray, Jennifer C; Habtemariam, Abraha; Winnig, Marcel; Meyerhof, Wolfgang; Sadler, Peter J

    2008-09-01

    The novel organometallic sandwich complexes [(eta(6)-p-cymene)Ru(eta(6)-aspartame)](OTf)(2) (1) (OTf = trifluoromethanesulfonate) and [(eta(6)-p-cymene)Os(eta(6)-aspartame)](OTf)(2) (2) incorporating the artificial sweetener aspartame have been synthesised and characterised. A number of properties of aspartame were found to be altered on binding to either metal. The pK(a) values of both the carboxyl and the amino groups of aspartame are lowered by between 0.35 and 0.57 pH units, causing partial deprotonation of the amino group at pH 7.4 (physiological pH). The rate of degradation of aspartame to 3,6-dioxo-5-phenylmethylpiperazine acetic acid (diketopiperazine) increased over threefold from 0.12 to 0.36 h(-1) for 1, and to 0.43 h(-1) for 2. Furthermore, the reduction potential of the ligand shifted from -1.133 to -0.619 V for 2. For the ruthenium complex 1 the process occurred in two steps, the first (at -0.38 V) within a biologically accessible range. This facilitates reactions with biological reductants such as ascorbate. Binding to and activation of the sweet taste receptor was not observed for these metal complexes up to concentrations of 1 mM. The factors which affect the ability of metal-bound aspartame to interact with the receptor site are discussed.

  15. Coordination of dibensothiophenes and corannulenes to organometallic ruthenium (II) fragments

    SciTech Connect

    Vecchi, Paul Anthony

    2005-01-01

    This dissertation contains five papers in the format required for journal publication which describe (in part) my research accomplishments as a graduate student at Iowa State University. This work can be broadly categorized as the binding of weakly-coordinating ligands to cationic organometallic ruthenium fragments, and consists of two main areas of study. Chapters 2-4 are investigations into factors that influence the binding of dibenzothiophenes to [Cp'Ru(CO)2(+ fragments, where Cp' = η5-C5H5 (Cp) and η5-C5Me5 (Cp*). Chapters 5 and 6 present the synthesis and structural characterization of complexes containing corannulene buckybowls that are η6-coordinated to [Cp*Ru(+ fragments. The first chapter contains a brief description of the difficulty in lowering sulfur levels in diesel fuel along with a review of corannulene derivatives and their metal complexes. After the final paper is a short summary of the work herein (Chapter 7). Each chapter is independent, and all equations, schemes, figures, tables, references, and appendices in this dissertation pertain only to the chapter in which they appear.

  16. Switching on elusive organometallic mechanisms with photoredox catalysis.

    PubMed

    Terrett, Jack A; Cuthbertson, James D; Shurtleff, Valerie W; MacMillan, David W C

    2015-08-20

    Transition-metal-catalysed cross-coupling reactions have become one of the most used carbon-carbon and carbon-heteroatom bond-forming reactions in chemical synthesis. Recently, nickel catalysis has been shown to participate in a wide variety of C-C bond-forming reactions, most notably Negishi, Suzuki-Miyaura, Stille, Kumada and Hiyama couplings. Despite the tremendous advances in C-C fragment couplings, the ability to forge C-O bonds in a general fashion via nickel catalysis has been largely unsuccessful. The challenge for nickel-mediated alcohol couplings has been the mechanistic requirement for the critical C-O bond-forming step (formally known as the reductive elimination step) to occur via a Ni(III) alkoxide intermediate. Here we demonstrate that visible-light-excited photoredox catalysts can modulate the preferred oxidation states of nickel alkoxides in an operative catalytic cycle, thereby providing transient access to Ni(III) species that readily participate in reductive elimination. Using this synergistic merger of photoredox and nickel catalysis, we have developed a highly efficient and general carbon-oxygen coupling reaction using abundant alcohols and aryl bromides. More notably, we have developed a general strategy to 'switch on' important yet elusive organometallic mechanisms via oxidation state modulations using only weak light and single-electron-transfer catalysts.

  17. Switching on elusive organometallic mechanisms with photoredox catalysis

    NASA Astrophysics Data System (ADS)

    Terrett, Jack A.; Cuthbertson, James D.; Shurtleff, Valerie W.; MacMillan, David W. C.

    2015-08-01

    Transition-metal-catalysed cross-coupling reactions have become one of the most used carbon-carbon and carbon-heteroatom bond-forming reactions in chemical synthesis. Recently, nickel catalysis has been shown to participate in a wide variety of C-C bond-forming reactions, most notably Negishi, Suzuki-Miyaura, Stille, Kumada and Hiyama couplings. Despite the tremendous advances in C-C fragment couplings, the ability to forge C-O bonds in a general fashion via nickel catalysis has been largely unsuccessful. The challenge for nickel-mediated alcohol couplings has been the mechanistic requirement for the critical C-O bond-forming step (formally known as the reductive elimination step) to occur via a Ni(III) alkoxide intermediate. Here we demonstrate that visible-light-excited photoredox catalysts can modulate the preferred oxidation states of nickel alkoxides in an operative catalytic cycle, thereby providing transient access to Ni(III) species that readily participate in reductive elimination. Using this synergistic merger of photoredox and nickel catalysis, we have developed a highly efficient and general carbon-oxygen coupling reaction using abundant alcohols and aryl bromides. More notably, we have developed a general strategy to `switch on' important yet elusive organometallic mechanisms via oxidation state modulations using only weak light and single-electron-transfer catalysts.

  18. Switching on Elusive Organometallic Mechanisms with Photoredox Catalysis

    PubMed Central

    Terrett, Jack A.; Cuthbertson, James D.; Shurtleff, Valerie W.; MacMillan, David W. C.

    2015-01-01

    Transition metal-catalyzed cross-coupling reactions have become one of the most utilized carbon–carbon and carbon–heteroatom bond-forming reactions in chemical synthesis. More recently, nickel catalysis has been shown to participate in a wide variety of C–C bond forming reactions, most notably Negishi, Suzuki–Miyaura, Stille, Kumada, and Hiyama couplings1,2. Despite the tremendous advances in C–C fragment couplings, the ability to forge C–O bonds in a general fashion via nickel catalysis has been largely unsuccessful. The challenge for nickel-mediated alcohol couplings has been the mechanistic requirement for the critical C–O bond forming step (formally known as the reductive elimination step) to occur via a Ni(III) alkoxide intermediate. In this manuscript, we demonstrate that visible light-excited photoredox catalysts can modulate the preferred oxidation states of nickel alkoxides in an operative catalytic cycle, thereby providing transient access to Ni(III) species that readily participate in reductive elimination. Using this synergistic merger of photoredox and nickel catalysis, we have developed a highly efficient and general carbon–oxygen coupling reaction using abundant alcohols and aryl bromides. More significantly, we have developed a general strategy to “switch on” important yet elusive organometallic mechanisms via oxidation state modulations using only weak light and single-electron transfer (SET) catalysts. PMID:26266976

  19. Synthesis, Characterization, and C-H Activation Reactions of Novel Organometallic O-donor Ligated Rh(III) Complexes

    SciTech Connect

    Tenn, William J.; Conley, Brian L.; Bischof, Steven M.; Periana, Roy A.

    2010-09-17

    The synthesis and characterization of the O-donor ligated, air and water stable organometallic complexes trans- (2), and cis-(hfac-O,O) 2Rh(CH3)(py) (3), trans-(hfac-O,O)2Rh(C6H5)(py) (4), cis-(hfac-O,O)2Rh(C6H5)(py) (5), and cis-(hfac-O,O)2Rh(Mes)(py) (6) (where hfac-O,O = κ 2-O,O-1,1,1,5,5,5-hexafluoroacetylacetonato) are reported. These compounds are analogues to the O-donor iridium complexes that are active catalysts for the hydroarylation and C–H activation reactions as well as the bis-acetylacetonato rhodium complexes, which we recently reported. The trans-complex 2 undergoes a quantitative trans to cis isomerization in cyclohexane to form 3, which activates C–H bonds in both benzene and mesitylene to form compounds 5 and 6, respectively. All of these compounds are air and water stable and do not lead to decomposition products. Complex 5 promotes hydroarylation of styrene by benzene to generate dihydrostilbene.

  20. Castability of Traditionally Wrought Ni-Based Superalloys for USC Steam Turbines

    SciTech Connect

    Jablonski, P D; Cowen, C J; Hawk, J A; Evens, N; Maziasz, P

    2011-02-27

    The high temperature components within conventional coal fired power plants are manufactured from ferritic/martensitic steels. In order to reduce greenhouse gas emissions the efficiency of pulverized coal steam power plants must be increased. The proposed steam temperature in the Advanced Ultra Supercritical (A-USC) power plant is high enough (760°C) that ferritic/martensitic steels will not work due to temperature limitations of this class of materials; thus Ni-based superalloys are being considered. The full size castings are quite substantial: ~4in thick, several feet in diameter and weigh 5-10,000lb each half. Experimental castings were quite a bit smaller, but section size was retained and cooling rate controlled in order to produce relevant microstructures. A multi-step homogenization heat treatment was developed in order to better deploy the alloy constituents. The castability of two traditionally wrought Ni-based superalloys to which minor alloy adjustments have been made in order to improve foundry performance is further explored.

  1. Thermosensitive Ni-based magnetic particles for self-controlled hyperthermia applications

    NASA Astrophysics Data System (ADS)

    Pandey, Sudip; Quetz, Abdiel; Aryal, Anil; Dubenko, Igor; Mazumdar, Dipanjan; Stadler, Shane; Ali, Naushad

    2017-04-01

    A number of ferromagnetic alloys in the bulk-form "thermoseeds" have been investigated for localized self-controlled hyperthermia treatment of cancer by substituting V, Mo, Cu, and Ga for Ni. The samples were prepared by arc-melting technique and annealed at 1223 K (950 °C) for 12 h in sealed quartz tubes. The structural, magnetic, and magnetocaloric properties of the samples were studied, using room temperature X-ray diffraction and a Superconducting Quantum Interference Device (SQUID) magnetometer. The magnetocaloric parameters (magnetic entropy changes, refrigeration capacity (RC), and hysteretic effects) have been calculated. It has been shown that recrystallization, i.e., annealing time and temperature, is crucial for controlling the heating characteristics of the seeds. A linear decrease in Curie temperature (TC) from 380 K (107 °C) to 200 K (-73 °C) was observed with increasing substitution of Ni by V, Mo, Cu, and Ga, while the magnetization value remained nearly constant for all substitutions. The optimal composition of these Ni-based alloys has been determined in order to allow self-controlling hyperthermia, implying a Curie temperature near the therapeutic level, 315-318 K (41-45 °C). The results showed that an extraordinary self-regulating heating effect has been achieved in Ni-based magnetic materials, which may create new vistas for hyperthermia cancer treatment.

  2. A study of microstructural characteristics of Ni-based superalloys at high temperatures

    NASA Technical Reports Server (NTRS)

    Lal, Ravindra B.; Aggarwal, M. D.

    1990-01-01

    The microstructural characteristics of the Ni-based superalloy MAR-M245(Hf) which is used in manufacturing the components of the Space Shuttle main engine are studied. These superalloys need optimum heat treatment to get the best results. To find out the optimum heat treatment, the techniques of differential thermal analysis (DTA) and the optical photomicrographs were utilized. In the first phase, the existing experimental equipment like cutting, grinding/polishing machines and metallurgical microscope were set up to cut/polish and take the photomicrographs. In the beginning of the project a Perkin Elmer differential thermal analyzer DTA1700 along with a temperature programmed and the needed computer interface was procured and made operational. In the second year a Leitz Metallux-3 hot state research microscope was also procured and installed for in-situ observation of the superalloy samples. The hot stage when tested for the first time alloyed the thermocouple with the Tantalum heating element and has now been installed. Samples of MAR-M246(Hf), MAR-M247, Waspaloy, Udimet-41, CMSX-3, and CMSX-3 (Polycrystalline and single crystals) were studied using a differential thermal analyzer and the results are reported. Photomicrographs of the Ni-based superalloy MAR-M246 (Hf) were recorded before and after heat treatment at certain temperatures. More heat treatments need to be done before a final inference can be reached.

  3. A synchrotron study of microstructure gradient in laser additively formed epitaxial Ni-based superalloy

    DOE PAGES

    Xue, Jiawei; Zhang, Anfeng; Li, Yao; ...

    2015-10-08

    Laser additive forming is considered to be one of the promising techniques to repair single crystal Ni-based superalloy parts to extend their life and reduce the cost. Preservation of the single crystalline nature and prevention of thermal mechanical failure are two of the most essential issues for the application of this technique. Here we employ synchrotron X-ray microdiffraction to evaluate the quality in terms of crystal orientation and defect distribution of a Ni-based superalloy DZ125L directly formed by a laser additive process rooted from a single crystalline substrate of the same material. We show that a disorientation gradient caused bymore » a high density of geometrically necessary dislocations and resultant subgrains exists in the interfacial region between the epitaxial and stray grains. This creates a potential relationship of stray grain formation and defect accumulation. In conclusion, the observation offers new directions on the study of performance control and reliability of the laser additive manufactured superalloys.« less

  4. Steam Oxidation Behavior of Advanced Steels and Ni-Based Alloys at 800 °C

    NASA Astrophysics Data System (ADS)

    Dudziak, T.; Boroń, L.; Deodeshmukh, V.; Sobczak, J.; Sobczak, N.; Witkowska, M.; Ratuszek, W.; Chruściel, K.

    2017-02-01

    This publication studies the steam oxidation behavior of advanced steels (309S, 310S and HR3C) and Ni-based alloys (Haynes® 230®, alloy 263, alloy 617 and Haynes® 282®) exposed at 800 °C for 2000 h under 1 bar pressure, in a pure water steam system. The results revealed that all exposed materials showed relatively low weight gain, with no spallation of the oxide scale within the 2000 h of exposure. XRD analysis showed that Ni-based alloys developed an oxide scale consisting of four main phases: Cr2O3 (alloy 617, Haynes® 282®, alloy 263 and Haynes® 230®), MnCr2O4 (alloy 617, Haynes® 282® and Haynes® 230®), NiCr2O4 (alloy 617) and TiO2 (alloy 263, Haynes® 282®). In contrast, advanced steels showed the development of Cr2O3, MnCr2O4, Mn7SiO12, FeMn(SiO4) and SiO2 phases. The steel with the highest Cr content showed the formation of Fe3O4 and the thickest oxide scale.

  5. Creep Crack Initiation and Growth Behavior for Ni-Base Superalloys

    NASA Astrophysics Data System (ADS)

    Nagumo, Yoshiko; Yokobori, A. Toshimitsu, Jr.; Sugiura, Ryuji; Ozeki, Go; Matsuzaki, Takashi

    The structural components which are used in high temperature gas turbines have various shapes which may cause the notch effect. Moreover, the site of stress concentration might have the heterogeneous microstructural distribution. Therefore, it is necessary to clarify the creep fracture mechanism for these materials in order to predict the life of creep fracture with high degree of accuracy. In this study, the creep crack growth tests were performed using in-situ observational testing machine with microscope to observe the creep damage formation and creep crack growth behavior. The materials used are polycrystalline Ni-base superalloy IN100 and directionally solidified Ni-base superalloy CM247LC which were developed for jet engine turbine blades and gas turbine blades in electric power plants, respectively. The microstructural observation of the test specimens was also conducted using FE-SEM/EBSD. Additionally, the analyses of two-dimensional elastic-plastic creep finite element using designed methods were conducted to understand the effect of microstructural distribution on creep damage formation. The experimental and analytical results showed that it is important to determine the creep crack initiation and early crack growth to predict the life of creep fracture and it is indicated that the highly accurate prediction of creep fracture life could be realized by measuring notch opening displacement proposed as the RNOD characteristic.

  6. Hot corrosion testing of Ni-based alloys and coatings in a modified Dean rig

    NASA Astrophysics Data System (ADS)

    Steward, Jason Reid

    Gas turbine blades are designed to withstand a variety of harsh operating conditions. Although material and coating improvements are constantly administered to increase the mean time before turbine refurbishment or replacement, hot corrosion is still considered as the major life-limiting factor in many industrial and marine gas turbines. A modified Dean rig was designed and manufactured at Tennessee Technological University to simulate the accelerated hot corrosion conditions and to conduct screening tests on the new coatings on Ni-based superalloys. Uncoated Ni-based superalloys, Rene 142 and Rene 80, were tested in the modified Dean rig to establish a testing procedure for Type I hot corrosion. The influence of surface treatments on the hot corrosion resistance was then investigated. It was found that grit-blasted specimens showed inferior hot corrosion resistance than that of the polished counterpart. The Dean rig was also used to test model MCrAlY alloys, pack cementation NiAl coatings, and electro-codeposited MCrAlY coatings. Furthermore, the hot corrosion attack on the coated-specimens were also assessed using a statistical analysis approach.

  7. Effect of inhomogeneous re-oxidation on Ni-based SOFC oxidation resistance

    NASA Astrophysics Data System (ADS)

    Lou, Kang; Wang, Feng Hui; Lu, Yong Jun; Zhao, Xiang

    2016-09-01

    Inhomogeneous re-oxidation, which causes graded NiO content along anode thickness, has been confirmed to be a key reason for Ni-based cell cracking during redox progress. In this paper, an analytical model is developed to estimate the impact of inhomogeneous re-oxidation on Ni-based solid oxide fuel cell (SOFC) oxidation resistance. And experiments, in which the SOFC was partially re-oxidized, were implemented for model trial. Model results show that electrolyte internal stress can be significantly reduced (from 367 MPa to 135 MPa, when the oxidation degree is 60%), and the electrolyte can remain intact even when the oxidation degree reaches about 70%, if the anode was re-oxidized uniformly. This impact of inhomogeneous re-oxidation on stress in the electrolyte decreases as the anode thickness increases. Scanning electron microscopic (SEM) images of partially oxidized anode cross-sections confirmed that Ni oxidation was inhomogeneous, in which the outer regions of the anode became almost fully oxidized, while the inner regions remained metallic. And the inhomogeneity increases with the redox times. Consequently, it is important to avoid gradients in NiO content during oxidation progress to prevent cell cracking.

  8. Steam Oxidation Behavior of Advanced Steels and Ni-Based Alloys at 800 °C

    NASA Astrophysics Data System (ADS)

    Dudziak, T.; Boroń, L.; Deodeshmukh, V.; Sobczak, J.; Sobczak, N.; Witkowska, M.; Ratuszek, W.; Chruściel, K.

    2017-03-01

    This publication studies the steam oxidation behavior of advanced steels (309S, 310S and HR3C) and Ni-based alloys (Haynes® 230®, alloy 263, alloy 617 and Haynes® 282®) exposed at 800 °C for 2000 h under 1 bar pressure, in a pure water steam system. The results revealed that all exposed materials showed relatively low weight gain, with no spallation of the oxide scale within the 2000 h of exposure. XRD analysis showed that Ni-based alloys developed an oxide scale consisting of four main phases: Cr2O3 (alloy 617, Haynes® 282®, alloy 263 and Haynes® 230®), MnCr2O4 (alloy 617, Haynes® 282® and Haynes® 230®), NiCr2O4 (alloy 617) and TiO2 (alloy 263, Haynes® 282®). In contrast, advanced steels showed the development of Cr2O3, MnCr2O4, Mn7SiO12, FeMn(SiO4) and SiO2 phases. The steel with the highest Cr content showed the formation of Fe3O4 and the thickest oxide scale.

  9. Organometallic Palladium Complexes with a Water-Soluble Iminophosphorane Ligand as Potential Anticancer Agents

    PubMed Central

    Carreira, Monica; Calvo-Sanjuán, Rubén; Sanaú, Mercedes; Marzo, Isabel; Contel, María

    2012-01-01

    The synthesis and characterization of a new water-soluble iminophosphorane ligand TPA=N-C(O)-2BrC6H4 (C,N-IM; TPA = 1,3,5-triaza-7-phosphaadamantane) 1 is reported. Oxidative addition of 1 to Pd2(dba)3 affords the orthopalladated dimer [Pd(μ-Br){C6H4(C(O)N=TPA-kC,N)-2}]2 (2) as a mixture of cis and trans isomers (1:1 molar ratio) where the iminophosphorane moeity behaves as a C,N-pincer ligand. By addition of different neutral or monoanionic ligands to 2, the bridging bromide can be cleaved and a variety of hydrophilic or water-soluble mononuclear organometallic palladium(II) complexes of the type [Pd{C6H4(C(O)N=TPA-kC,N)-2}(L-L)] (L-L = acac (3); S2CNMe2 (4); 4,7-Diphenyl-1,10-phenanthrolinedisulfonic acid disodium salt C12H6N2(C6H4SO3Na)2 (5)); [Pd{C6H4(C(O)N=TPA-kC,N)-2}(L)Br] (L = P(mC6H4SO3Na)3 (6); P(3-Pyridyl)3 (7)) and, [Pd(C6H4(C(O)N=TPA)-2}(TPA)2Br] (8) are obtained as single isomers. All new complexes were tested as potential anticancer agents and their cytotoxicity properties were evaluated in vitro against human Jurkat-T acute lymphoblastic leukemia cells, normal T-lymphocytes (PBMC) and DU-145 human prostate cancer cells. Compounds [Pd(μ-Br){C6H4(C(O)N=TPA-kC,N)-2}]2 (2) and [Pd{C6H4(C(O)N=TPA-kC,N)-2}(acac)] 3 (which has been crystallographically characterized) display the higher cytotoxicity against the above mentioned cancer cell lines while being less toxic to normal T-lymphocytes (peripheral blood mononuclear cells: PBMC). In addition, 3 is very toxic to cisplatin resistant Jurkat shBak indicating a cell death pathway that may be different to that of cisplatin. The interaction of 2 and 3 with plasmid (pBR322) DNA is much weaker than that of cisplatin pointing to an alternative biomolecular target for these cytotoxic compounds. All the compounds show an interaction with human serum albumin (HSA) faster than that of cisplatin. PMID:23066172

  10. Combining Organometallic Reagents, the Sulfur Dioxide Surrogate DABSO, and Amines: A One-Pot Preparation of Sulfonamides, Amenable to Array Synthesis**

    PubMed Central

    Deeming, Alex S; Russell, Claire J; Willis, Michael C

    2015-01-01

    We describe a method for the synthesis of sulfonamides through the combination of an organometallic reagent, a sulfur dioxide equivalent, and an aqueous solution of an amine under oxidative conditions (bleach). This simple reaction protocol avoids the need to employ sulfonyl chloride substrates, thus removing the limitation imposed by the commercial availability of these reagents. The resultant method allows access to new chemical space, and is also tolerant of the polar functional groups needed to impart favorable physiochemical properties required for medicinal chemistry and agrochemistry. The developed chemistry is employed in the synthesis of a targeted 70 compound array, prepared using automated methods. The array achieved a 93 % success rate for compounds prepared. Calculated molecular weights, lipophilicities, and polar surface areas are presented, demonstrating the utility of the method for delivering sulfonamides with drug-like properties. PMID:25431118

  11. Molecular metal catalysts on supports: organometallic chemistry meets surface science.

    PubMed

    Serna, Pedro; Gates, Bruce C

    2014-08-19

    Recent advances in the synthesis and characterization of small, essentially molecular metal complexes and metal clusters on support surfaces have brought new insights to catalysis and point the way to systematic catalyst design. We summarize recent work unraveling effects of key design variables of site-isolated catalysts: the metal, metal nuclearity, support, and other ligands on the metals, also considering catalysts with separate, complementary functions on supports. The catalysts were synthesized with the goal of structural simplicity and uniformity to facilitate incisive characterization. Thus, they are essentially molecular species bonded to porous supports chosen for their high degree of uniformity; the supports are crystalline aluminosilicates (zeolites) and MgO. The catalytic species are synthesized in reactions of organometallic precursors with the support surfaces; the precursors include M(L)2(acetylacetonate)1-2, with M = Ru, Rh, Ir, or Au and the ligands L = C2H4, CO, or CH3. Os3(CO)12 and Ir4(CO)12 are used as precursors of supported metal clusters, and some such catalysts are made by ship-in-a-bottle syntheses to trap the clusters in zeolite cages. The simplicity and uniformity of the supported catalysts facilitate precise structure determinations, even in reactive atmospheres and during catalysis. The methods of characterizing catalysts in reactive atmospheres include infrared (IR), extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES), and nuclear magnetic resonance (NMR) spectroscopies, and complementary methods include density functional theory and atomic-resolution aberration-corrected scanning transmission electron microscopy for imaging of individual metal atoms. IR, NMR, XANES, and microscopy data demonstrate the high degrees of uniformity of well-prepared supported species. The characterizations determine the compositions of surface metal complexes and clusters, including the ligands and the metal

  12. The direct synthesis of organic and organometallic-containing MICA-type aluminosilicates

    SciTech Connect

    Carrado, K.A.; Awaluddin, A.

    1993-08-01

    Layer-silicate clay structures can provide supramolecular organization for catalysis, chiral reactions, colloid science, and electron transfer. The authors have successfully modified the experimental preparations of several different layer silicates in order to incorporate a wide variety of organic and organometallic molecules in the clay galleries. Synthesis and physical characterization of these materials are described and compared to ion-exchanged natural clay analogs. In addition, the photophysical properties of organometallic Ru(II) complexes incorporated by direct hydrothermal crystallization into synthetic clays were measured. 3 tabs, 21 refs.

  13. Performance of Alumina-Forming Austenitic Steels, Fe-base and Ni-base alloys exposed to metal dusting environments

    SciTech Connect

    Vande Put Ep Rouaix, Aurelie; Unocic, Kinga A; Pint, Bruce A; Brady, Michael P

    2011-01-01

    A series of conventional Fe- and Ni- base, chromia- and alumina- forming alloys, and a newly developed creep-resistant, alumina-forming austenitic steel were developed and its performance relative to conventional Fe- and Ni-based chromia-forming alloys was evaluated in metal dusting environments with a range of water vapor contents. Five 500h experiments have been performed at 650 C with different water vapor contents and total pressures. Without water vapor, the Ni-base alloys showed greater resistance to metal dusting than the Fe-base alloys, including AFA. However, with 10-28% water vapor, more protective behavior was observed with the higher-alloyed materials and only small mass changes were observed. Longer exposure times are in progress to further differentiate performance.

  14. Two-step solid-state synthesis of PEPPSI-type compounds.

    PubMed

    Adams, Christopher J; Lusi, Matteo; Mutambi, Emily M; Guy Orpen, A

    2015-06-14

    The two-step mechanochemical preparation of carbene-pyridine complexes of palladium and platinum is reported. The organometallic products, which represent a class of commercially available catalysts, are rapidly formed in excellent yield proving solvent-free synthesis to be a viable synthetic alternative even in the case of NHC-containing compounds.

  15. A study of microstructural characteristics of Ni-based superalloys at high temperatures

    NASA Technical Reports Server (NTRS)

    Lal, R. B.; Aggarwal, M. D.

    1987-01-01

    The microstructure of the Ni-based superalloy MAR-M246 (Hf) which is used in manufacturing the components of the Space Shuttle Main Engine was investigated. In the first year, the superalloy will be studied using optical photomicrographs and the differential thermal analysis. During this period, the existing experimental equipment like cutting, grinding/polishing machines, metallurgical microscope will be used to but/polish and take the photomicrographs. At present, only a 35 mm camera attachment with the olympus inverted metallurgical microscope is being used. Due to this, there was considerable delay in processing photographs. A Perkin-Elmer Differential Thermal Analyzer (DTA-1700) was ordered and finally installed on April 28, 1987. Preliminary test runs were made on silver as well as MAR-M246 (Hf).

  16. Development of Ni-based Sulfur Resistant Catalyst for Diesel Reforming

    SciTech Connect

    Gunther Dieckmann

    2006-06-30

    In order for diesel fuel to be used in a solid oxide fuel cell auxiliary power unit, the diesel fuel must be reformed into hydrogen, carbon monoxide and carbon dioxide. One of the major problems facing catalytic reforming is that the level of sulfur found in low sulfur diesel can poison most catalysts. This report shows that a proprietary low cost Ni-based reforming catalyst can be used to reform a 7 and 50 ppm sulfur containing diesel fuel for over 500 hours of operation. Coking, which appears to be route of catalyst deactivation due to metal stripping, can be controlled by catalyst modifications, introduction of turbulence, and/or by application of an electromagnetic field with a frequency from {approx}50 kHz to 13.56 MHz with field strength greater than about 100 V/cm and more preferably greater about 500 V/cm.

  17. A study of microstructural characteristics and differential thermal analysis of Ni-based superalloys

    NASA Technical Reports Server (NTRS)

    Aggarwal, M. D.; Lal, R. B.; Oyekenu, Samuel A.; Parr, Richard; Gentz, Stephen

    1989-01-01

    The objective of this work is to correlate the mechanical properties of the Ni-based superalloy MAR M246(Hf) used in the Space Shuttle Main Engine with its structural characteristics by systematic study of optical photomicrographs and differential thermal analysis. The authors developed a method of predicting the liquidus and solidus temperature of various nickel based superalloys (MAR-M247, Waspaloy, Udimet-41, polycrystalline and single crystals of CMSX-2 and CMSX-3) and comparing the predictions with the experimental differential thermal analysis (DTA) curves using Perkin-Elmer DTA 1700. The method of predicting these temperatures is based on the additive effect of the components dissolved in nickel. The results were compared with the experimental values.

  18. FeNi-based magnetoimpedance multilayers: Tailoring of the softness by magnetic spacers

    NASA Astrophysics Data System (ADS)

    Svalov, A. V.; Fernandez, E.; Garcia-Arribas, A.; Alonso, J.; Fdez-Gubieda, M. L.; Kurlyandskaya, G. V.

    2012-04-01

    The microstructure and magnetic properties of sputtered permalloy films and FeNi(170 nm)/X/FeNi(170 nm) (X = Co, Fe, Gd, Gd-Co) sandwiches were studied. Laminating of the thick FeNi film with various spacers was done in order to control the magnetic softness of FeNi-based multilayers. In contrast to the Co and Fe spacers, Gd and Gd-Co magnetic spacers improved the softness of the FeNi/X/FeNi sandwiches. The magnetoimpedance responses were measured for [FeNi/Ti(6 nm)]2/FeNi and [FeNi/Gd(2 nm)]2/FeNi multilayers in a frequency range of 1-500 MHz: for all frequencies under consideration the highest magnetoimpedance variation was observed for [FeNi/Gd(2 nm)]2/FeNi multilayers.

  19. Corrosion behavior aspects of Ni-base self-fluxing coatings

    NASA Astrophysics Data System (ADS)

    Paulin, C.; Chicet, D. L.; Istrate, B.; Panţuru, M.; Munteanu, C.

    2016-08-01

    Due to the development of thermal spray deposition technologies, thus obtained layers have more applications and fields of use. One of the coatings with increased application is the one produced from Ni-based self-fluxing alloys, which besides the good wear resistance, shows a satisfactory corrosion resistance. In this study it was observed the behavior of three types of coatings produced by Flame Spray method, both at wear and especially corrosion in the environment simulating acid rain. As a result of the experiments it was found that these layers became compact enough after applying the self-fluxing heat treatment, so in their structure are not present defects such as pores and micro-cracks, unmelted particles etc., which could be points of corrosion initiation.

  20. Ni-base superalloy powder-processed porous layer for gas cooling in extreme environments

    DOE PAGES

    White, Emma M. H.; Heidloff, Andrew J.; Byrd, David J.; ...

    2016-05-26

    Extreme high temperature conditions demand novel solutions for hot gas filters and coolant access architectures, i.e., porous layers on exposed components. These high temperatures, for example in current turbine engines, are at or exceeding current material limits for high temperature oxidation/corrosion, creep resistance, and, even, melting temperature. Thus novel blade designs allowing greater heat removal are required to maintain airfoil temperatures below melting and/ or rapid creep deformation limits. Gas atomized Ni-base superalloy powders were partially sintered into porous layers to allow full-surface, transpirational cooling of the surface of airfoils. Furthermore, these powder-processed porous layers were fully characterized for surface,more » morphology, cross-sectional microstructure, and mechanical strength characteristics. A sintering model based on pure Ni surface diffusion correlated well with the experimental results and allowed reasonable control over the partial sintering process to obtain a specified level of porosity within the porous layer.« less

  1. Microstructure and creep resistance of a diffusionally aluminized Ni-base superalloy

    NASA Astrophysics Data System (ADS)

    Sah, Injin; Kim, Sung Hwan; Jang, Changheui

    2016-11-01

    An aluminide layer was formed on a wrought Ni-base superalloy by the diffusional aluminizing method, which involves a physical vapor deposition of Al followed by two-step heat treatment in vacuum. Microstructural analysis revealed the presence of an aluminide layer, inter-diffusion zone (IDZ), and affected substrate, all of which developed due to the inter-diffusion of deposited Al and elements in the matrix. In addition, a wide carbide free zone, in which grain boundaries were mostly denuded of carbides, was found below the IDZ. Depth profiling analysis using a glow discharge spectrometer confirmed the reduced carbon content in the carbide free zone. At 900 °C, the diffusionally aluminized specimens showed a decrease in creep-rupture life caused by the presence of the carbide free zone. Fracture surface and cross-section microstructure observation confirmed the detrimental effect of the carbide free zone on the creep resistance of the diffusionally aluminized Alloy 617.

  2. Reduction of chromium in Ni-base superalloys through element substitution and rapid solidification processing

    NASA Technical Reports Server (NTRS)

    Fraser, H. D.; Muddl, B. C.

    1982-01-01

    The reduction in the use of Cr in Ni base superalloys by the combined approaches of both elemental substitution and rapid solidification processing is studied. The elements Si, Zr, Y and Hf were chosen as potential partial substitutes for Cr in Waspaloy and IN 713LC sine their separate addition to other alloys has previously resulted in enhanced oxidation resistance. The roles of Cr and these replacement elements in determining the microstructure and properties are evaluated. The elements Si, Zr, and Y and Hf are used as partial replacements for Cr in the base superalloys and these resultant alloys are processed using rapid solidification techniques. The mechanical properties and oxidation resistance of the processed materials are evaluated. The microstructure is characterized using state of the art techniques (e.g. analytical transmission electron microscopy), and the mechanism by which these structures are produced is determined.

  3. Microstructural and Mechanical Properties of Ni-Base Thermal Spray Coatings Deposited by Flame Spraying

    NASA Astrophysics Data System (ADS)

    Amokrane, Bradai Mohand; Abdelhamid, Sadeddine; Youcef, Mouadji; Abderrahim, Benabbas; Nedjemeddine, Bounar; Ahmed, Mammeri

    2011-10-01

    In this work, two different Ni-base powders, namely, ProXon 21021 (P21) and ProXon 21031 (P31), were sprayed onto a steel substrate 35CrMo4 using a thermal flame spray technique. The morphology and chemical composition of the phases that are present in the powders and coatings were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The hardness and wear resistance of the coatings were investigated. The XRD analysis revealed that the phases present in the coatings are different from the initial powders. In addition, some inhomogeneities such as oxides, porosity, and unmelted particles were observed by SEM. It was found that the P31 spray-coated exhibited higher microhardness, higher wear resistance, and significantly lower friction coefficient in comparison with those of P21 coatings.

  4. Interdiffusion Behavior of Pt-Diffused gamma+gamma' Coatings on Ni-Based Superalloys

    SciTech Connect

    Zhang, Ying; Stacy, J P; Pint, Bruce A; Haynes, James A; Hazel, Brian T; Nagaraj, Ben

    2008-01-01

    Platinum-diffused {gamma} + {gamma}{prime} coatings ({approx} 20 at.% Al, {approx} 22 at.% Pt) were synthesized on Rene 142 and Rene N5 Ni-based superalloys by electroplating the substrates with {approx} 7 {micro}m of Pt, followed by an annealing treatment in vacuum at 1175 C. In order to study the compositional and microstructural evolution of these coatings at elevated temperatures, interdiffusion experiments were carried out on coated specimens in the temperature range of 900-1050 C for various durations. Composition profiles of the alloying elements in the {gamma} + {gamma}{prime} coatings before and after diffusion experiments were determined by electron probe microanalysis. Although the change of the Al content in the coatings was minimal under these interdiffusion conditions, the decrease of the Pt content and increase of the diffusion depth of Pt into the substrate alloys were significant. A preliminary diffusion model was used to estimate the Pt penetration depth after diffusion.

  5. Ni-base superalloy powder-processed porous layer for gas cooling in extreme environments

    SciTech Connect

    White, Emma M. H.; Heidloff, Andrew J.; Byrd, David J.; Anderson, Ross D.; Anderson, Iver E.

    2016-05-26

    Extreme high temperature conditions demand novel solutions for hot gas filters and coolant access architectures, i.e., porous layers on exposed components. These high temperatures, for example in current turbine engines, are at or exceeding current material limits for high temperature oxidation/corrosion, creep resistance, and, even, melting temperature. Thus novel blade designs allowing greater heat removal are required to maintain airfoil temperatures below melting and/ or rapid creep deformation limits. Gas atomized Ni-base superalloy powders were partially sintered into porous layers to allow full-surface, transpirational cooling of the surface of airfoils. Furthermore, these powder-processed porous layers were fully characterized for surface, morphology, cross-sectional microstructure, and mechanical strength characteristics. A sintering model based on pure Ni surface diffusion correlated well with the experimental results and allowed reasonable control over the partial sintering process to obtain a specified level of porosity within the porous layer.

  6. An anisotropic micromechanics model for predicting the rafting direction in Ni-based single crystal superalloys

    NASA Astrophysics Data System (ADS)

    Li, Shuang-Yu; Wu, Wen-Ping; Chen, Ming-Xiang

    2016-02-01

    An anisotropic micromechanics model based on the equivalent inclusion method is developed to investigate the rafting direction of Ni-based single crystal superalloys. The micromechanical model considers actual cubic structure and orthogonal anisotropy properties. The von Mises stress, elastic strain energy density, and hydrostatic pressure in different inclusions of micromechanical model are calculated when applying a tensile or compressive loading along the [001] direction. The calculated results can successfully predict the rafting direction for alloys exhibiting a positive or a negative mismatch, which are in agreement with pervious experimental and theoretical studies. Moreover, the elastic constant differences and mismatch degree of the matrix and precipitate phases and their influences on the rafting direction are carefully discussed.

  7. DISTRIBUTION OF ORGANIC AND ORGANOMETALLIC COMPOUNDS IN SEDIMENTS FROM THE GULF OF MEXICO

    EPA Science Inventory

    In 1994, over 200 sediment samples were collected in accordance with EPA's Environmental Monitoring and Assessment (EMAP) probabilistic sampling protocol from coastal and estuarine locations in the Louisianian Province (Gulf of Mexico). Organic extracts of homogenized aliquots we...

  8. Photodissociation dynamics of organometallic compounds: Study of the dihydride complex H2Fe(CO)4

    SciTech Connect

    Heitz, M. C.; Daniel, C.

    1996-04-01

    The photodissociation of the dihydride complex H2Fe(CO)4 has been investigated by a theoretical approach, involving time-dependent wave packet propagations on potential energy surfaces (PES) obtained from CASSCF-MRCI calculations. A two dimensions simulation is proposed, allowing the study of two concurrents processes, namely photoinduced elimination of molecular hydrogen vs loss of a carbonyl ligand. Three singlet excited states {sup 1}bA1(x{sup 2}-y{sup 2}{yields}{sigma}g*), {sup 1}aB2(x{sup 2}-y{sup 2}{yields}{sigma}u*), {sup 1}aB1(yz{yields}{sigma}g*) has been identified in the range of energy corresponding to the experimental absorption spectrum. Wave packets propagations performed separately on the three PES describe the elementary processes contributing to the photochemical behavior of the molecule. The absorption spectrum reflecting these different processes, has been calculated, using the time dependent formalism.

  9. Secondary Reaction Zone Formations in coated Ni-base Single Crystal Superalloys

    NASA Astrophysics Data System (ADS)

    Suzuki, A.; Rae, C. M. F.

    2009-05-01

    Ruthenium (Ru) has been added to the latest 4th Generation Ni-base superalloys to improve phase stability and modify creep life. Various coatings are routinely applied to these advanced alloys to protect the turbine blade at elevated temperature, however, this creates several problems such as the precipitation of brittle Topologically Close-Packed (TCP) phases and the formation of Secondary Reaction Zones (SRZ). The SRZ forms under the plat-aluminized coating of turbine blades and consists of γ, γ and TCP phases growing into substrate by the migration of high-angle grain boundaries. Surface residual stress and chemical super-saturation of alloying elements are associated to SRZ formation. In the thin sections of high-pressure turbine blades this is critical in determining blade performance and longevity. It is essential to know how Ru additions affect coating and SRZ morphologies during exposure. In this study, we focus on the effects of three variables on the SRZ formation: Ru concentration, alloy composition in Ru-containing alloys and surface finish. A series of Platinum-Aluminised superalloys containing 2-5wt% Ru and having various surface finishes was studied after isothermal exposure at 1100°C for up to 500h. The alloys were classified into two groups by their distinctive SRZ morphology. At the lowest Ru levels sporadic formation of SRZ was observed, whilst a continuous SRZ was formed in the higher Ru alloys. EBSD analysis revealed that the latter group have a higher nucleation rate of individual SRZ grains and also showed more rapid SRZ growth. The precipitation of TCPs in the substrate also inhibited the growth of the SRZ towards the end of the exposure further reducing the penetration of the SRZ into the substrate. It is concluded that Ru-additions to Ni-base superalloys are effective in impeding TCP phase formation in the substrate, but increase both the extent and the rate of SRZ formation beneath coating.

  10. Microstructural characterization of a new mechanically alloyed Ni-base ODS superalloy powder

    SciTech Connect

    Seyyed Aghamiri, S.M.; Shahverdi, H.R.; Ukai, S.; Oono, N.; Taya, K.; Miura, S.; Hayashi, S.; Okuda, T.

    2015-02-15

    The microstructure of a new Ni-base oxide dispersion strengthened superalloy powder was studied for high temperature gas turbine applications after the mechanical alloying process. In this study, an atomized powder with a composition similar to the CMSX-10 superalloy was mechanically alloyed with yttria and Hf powders. The mechanically alloyed powder included only the supersaturated solid solution γ phase without γ′ and yttria provided by severe plastic deformation, while after the 3-step aging, the γ′ phase was precipitated due to the partitioning of Al and Ta to the γ′ and Co, Cr, Re, W, and Mo to the γ phase. Mechanical alloying modified the morphology of γ′ to the new coherent γ–γ′ nanoscale lamellar structure to minimize the elastic strain energy of the precipitation, which yielded a low lattice misfit of 0.16% at high temperature. The γ′ lamellae aligned preferentially along the elastically soft [100] direction. Also, the precipitated oxide particles were refined in the γ phase by adding Hf from large incoherent YAlO{sub 3} to fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles with the average size of 7 nm and low interparticle spacing of 76 nm. - Highlights: • A new Ni-base ODS superalloy powder was produced by mechanical alloying. • The nanoscale γ–γ′ lamellar structure was precipitated after the aging treatment. • Fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles were precipitated by addition of Hf.

  11. Organometallic single source precursors for chemical vapor deposition of metal chalcogenides

    NASA Astrophysics Data System (ADS)

    Seidler, Dean Jerry

    The group 14--16 compounds with the general formula (Bn2SnE)3, (Bn3Sn)2E, and Bn 2Sn(EBn)2, where E = S or Se, were synthesized and investigated as potential single-source precursors for the preparation of tin chalcogenides. Each precursor was pyrolyzed under an inert atmosphere. Decomposition took place at relatively mild conditions (<400°C). The cyclic molecules, (Bn2SnS)3 and (Bn2SnSe)3, produced tin sulfide and tin selenide, respectively. The samples were XRD phase pure, and combustion analysis indicated less than 1% carbon present in the final product. The acyclic precursors, (Bn3Sn)2S and (Bn 3Sn)2Se, yielded a mixture of the tin chalcogenide and elemental tin with carbon content <1%. The pyrolysis of Bn2Sn(SBn) 2 and Bn2Sn(SeBn)2 produced SnS2 and SnSe2, respectively, with carbon contamination <3%. The only volatile by-product detected from the pyrolysis of these compounds was bibenzyl, indicating all of the tin and chalcogen were left behind in the solid state product. Solid solutions could be generated by combining (Bn 2SnS)3 and (Bn2SnSe)3, and pyrolyzing the mixture. Combinations of Bn2Sn(SBn)2 and Bn 2Sn(SeBn)2 yielded products with some solid solution character; however, some phase separation was indicated in the XRD patterns. Bn3SnSBn and (tert-Bu2SnS)2 were pyrolyzed to produce bulk samples of SnS and also used as single-source precursors for the chemical vapor deposition of thin films of SnS on glass and halite substrates. The composition and morphology of the products, both as bulk materials and thin films, were influenced by the structure of the organometallic precursor, the nature of the leaving group attached to the metal (or chalcogen), and the nature of the film substrate.

  12. Nanoscaled tin dioxide films processed from organotin-based hybrid materials: an organometallic route toward metal oxide gas sensors

    NASA Astrophysics Data System (ADS)

    Renard, Laetitia; Babot, Odile; Saadaoui, Hassan; Fuess, Hartmut; Brötz, Joachim; Gurlo, Aleksander; Arveux, Emmanuel; Klein, Andreas; Toupance, Thierry

    2012-10-01

    Nanocrystalline tin dioxide (SnO2) ultra-thin films were obtained employing a straightforward solution-based route that involves the calcination of bridged polystannoxane films processed by the sol-gel process from bis(triprop-1-ynylstannyl)alkylene and -arylene precursors. These films have been thoroughly characterized by FTIR, contact angle measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force (AFM) and scanning electron (SEM) microscopies. Annealing at a high temperature gave 30-35 nm thick cassiterite SnO2 films with a mean crystallite size ranging from 4 to 7 nm depending on the nature of the organic linker in the distannylated compound used as a precursor. In the presence of H2 and CO gases, these layers led to highly sensitive, reversible and reproducible responses. The sensing properties were discussed in regard to the crystallinity and porosity of the sensing body that can be tuned by the nature of the precursor employed. Organometallic chemistry combined with the sol-gel process therefore offers new possibilities toward metal oxide nanostructures for the reproducible and sensitive detection of combustible and toxic gases.Nanocrystalline tin dioxide (SnO2) ultra-thin films were obtained employing a straightforward solution-based route that involves the calcination of bridged polystannoxane films processed by the sol-gel process from bis(triprop-1-ynylstannyl)alkylene and -arylene precursors. These films have been thoroughly characterized by FTIR, contact angle measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force (AFM) and scanning electron (SEM) microscopies. Annealing at a high temperature gave 30-35 nm thick cassiterite SnO2 films with a mean crystallite size ranging from 4 to 7 nm depending on the nature of the organic linker in the distannylated compound used as a precursor. In the presence of H2 and CO gases, these layers led to highly sensitive, reversible and reproducible

  13. Application of Organometallic Catalysis to the Commercial Production of L-DOPA.

    ERIC Educational Resources Information Center

    Knowles, W. S.

    1986-01-01

    Shows how asymmetric organometallic catalysts can be used to make complex organic molecules with extremely high enantioselectivity. The molecule considered is l-3, 4-dihydroxyphenylalanine (L-DOPA), an amino acid which was found to be effective in the treatment of Parkinson's disease. (JN)

  14. Molecular tectonics: heterometallic coordination networks based on a Pt(II) organometallic metallatecton.

    PubMed

    Zigon, Nicolas; Kyritsakas, Nathalie; Hosseini, Mir Wais

    2015-08-28

    Combinations of a neutral organometallic tecton based on a square planar Pt(ii) complex bearing two triphenylphosphine groups and two 4-ethynylpyridyl coordinating moieties in trans positions, with various metal halides (MX2, M = Co(ii), Ni(ii), Cd(ii), X = Cl(-) or Br(-)) lead to the formation of 2D grid type heterobimetallic coordination networks in the crystalline phase.

  15. New methodologies for construction of hyperbranched organic and organometallic polymers

    NASA Astrophysics Data System (ADS)

    Xu, Kaitian

    2000-10-01

    A series of completely soluble hyperbranched polymers were synthesized by polycyclotrimerization of diynes for the first time. TaCl5-Ph 4Sn was found to be the effective catalyst and toluene to be the efficient solvent. A possible polycyclotrimerization mechanism via tantalacyclopentadiene intermediates is proposed. The polymerization processes including initiation, propagation and termination are analyzed. The unique backbiting reaction was found to be a plausible way to terminate the propagation chain. Conformations of the diynes greatly affect the occurrence of backbiting reaction and affect the solubility of resultant polymers to certain extent. Diynes with short spacers such as 1,5-hexadiyne (21 ); 1,6-heptadiyne (22); 1,7-octadiyne (23); and 1,8-nonadiyne (17); possess a conformation in which the two triple bonds locate closely. Such a conformation makes the backbiting termination to occur easily. Thus, soluble polymers are readily formed from these diynes. For the diynes of long spacers, a conformation with two far-separating triple bonds dramatically reduces the chance of backbiting reaction. Consequently, only partially soluble or insoluble polymers could be prepared. In the polycyclotrimerization of internal diynes, hexasubstituted benzene rings were formed. The steric effect of the terminal substituents plays an important role in the polymerization reaction. Internal diynes with bulky substituents such as 1,9-bis(trimethylsilyl)-1,8-nonadiyne (74), 1,6-bis(dimethylphenylsilyl)-1,5-hexadiyne (75), 1,8-bis(dimethylphenylsilyl)-1,7-octadiyne (76) gave little amount of polymers. Internal diynes with less bulky substituents and short spacers [e.g. 3,9-dodecadiyne (78) and 2,9-undecadiyne (79)] offered soluble polymers. In the study on hyperbranched organometallic polymers, a new methodology for the preparation of hyperbranched polysilynes was developed. Ceramization of the hyperbranched polymers produced mesoporous magnetoceramic materials. The compositions

  16. Non-vacuum sintering process of WC/W2C reinforced Ni-based coating on steel

    NASA Astrophysics Data System (ADS)

    Lyu, Yezhe; Sun, Yufu; Yang, Yong

    2016-03-01

    Ni-based composite coatings containing varied contents of tungsten carbides on low carbon steel were fabricated. Effects of sintering temperature and tungsten carbides contents on the surface, interface, microstructure and wear resistance of the coatings were investigated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Vickers microhardness tester, bulk hardness tester and pin-on-disc tribometer. The results indicated that with appropriate sintering temperature (1230 °C), smooth coating surfaces can be achieved. Favorable interfaces about 200 μm can be got that both the chemical composition and property of the interfacial region showed gradual transitions from the substrates to the coatings. Microstructure of the coatings consists of tungsten carbides and M7C3/M23C6 in the matrix. With excessive sintering temperature, tungsten carbides tend to dissolve. Ni-based coatings containing tungsten carbides showed much higher level of bulk hardness and wear resistance than ISO Fe360A and ASTM 1566 steels. With increasing contents of tungsten carbides from 25% to 40%, bulk hardness of Ni-based coatings gradually increased. Ni-based coating with 35% tungsten carbides performed the best wear resistance.

  17. Investigation on corrosion behavior of Ni-based alloys in molten fluoride salt using synchrotron radiation techniques

    NASA Astrophysics Data System (ADS)

    Liu, Min; Zheng, Junyi; Lu, Yanling; Li, Zhijun; Zou, Yang; Yu, Xiaohan; Zhou, Xingtai

    2013-09-01

    Ni-based alloys have been selected as the structural materials in molten-salt reactors due to their high corrosion resistance and excellent mechanical properties. In this paper, the corrosion behavior of some Ni-based superalloys including Inconel 600, Hastelloy X and Hastelloy C-276 were investigated in molten fluoride salts at 750 °C. Morphology and microstructure of corroded samples were analyzed using scanning electron microscope (SEM), synchrotron radiation X-ray microbeam fluorescence (μ-XRF) and synchrotron radiation X-ray diffraction (SR-XRD) techniques. Results from μ-XRF and SR-XRD show that the main depleted alloying element of Ni-based alloys in molten fluoride salt is Cr. In addition, the results indicate that Mo can enhance the corrosion resistance in molten FLiNaK salts. Among the above three Ni-based alloys, Hastelloy C-276 exhibits the best corrosion resistance in molten fluoride salts 750 °C. Higher-content Mo and lower-content Cr in Hastelloy C-276 alloy were responsible for the better anti-corrosive performance, compared to the other two alloys.

  18. Grain boundary engineering of powder-processed Ni-base superalloy RR1000

    NASA Astrophysics Data System (ADS)

    Detrois, Martin

    Grain boundary engineering (GBE) has been used to improve the properties of various polycrystalline materials by optimization of their grain boundary network. Traditional processing routes for GBE often require multiple iterations of cold work followed by short annealing cycles where each iteration imparts a modest increase in the fraction of special grain boundaries. Multiple iterations are then required to achieve sufficiently high fractions (>50%) that result in the improved properties. Thus, this GBE approach is not suitable for the fabrication of large, complex-shaped structures and leads to added manufacturing lead time and cost. In this investigation, the Ni-base superalloy RR1000 used as turbine discs in gas turbine engines manufactured by Rolls-Royce, was considered for GBE using alternative processing routes more suitable to the forging of Ni-base superalloy components. A preliminary study of the effects of hot deformation parameters closer to typical industrial processing revealed that the length fraction of Sigma3 boundaries increased from 35% to 52% following a single deformation/anneal cycle. Deformation parameters that resulted in strain accommodation via superplastic flow did not enhance the formation of Sigma3 boundaries upon annealing. Whereas deformation parameters that resulted in a dominant dislocation-based plasticity flow mechanism promoted the formation of annealing twins. Using misorientation maps and by estimating the stored strain energy from deformation, equations for the length fraction and density of Sigma3 boundaries were generated for high-temperature GBE of RR1000. The grain boundary characters obtained via high-temperature deformation, however, are less ideal than those resulting from traditional cold rolling. The underlying mechanisms responsible for the formation of Sigma3n boundaries during high-temperature GBE were further investigated. A larger starting grain size prior to deformation was found to be unfavorable to the

  19. Preliminary Investigations of Joining Technologies for Attaching Refractory Metals to Ni-Based Superalloys

    NASA Technical Reports Server (NTRS)

    Gould, Jerry E.; Ritzert, Frank J.; Loewenthal, William S.

    2006-01-01

    In this study, a range of joining technologies has been investigated for creating attachments between refractory metal and Ni-based superalloys. Refractory materials of interest include Mo-47%Re, T-111, and Ta-10%W. The Ni-based superalloys include Hastelloy X and MarM 247. During joining with conventional processes, these materials have potential for a range of solidification and intermetallic formation-related defects. For this study, three non-conventional joining technologies were evaluated. These included inertia welding, electro-spark deposition (ESD) welding, and magnetic pulse welding (MPW). The developed inertia welding practice closely paralleled that typically used for the refractory metals alloys. Metallographic investigations showed that forging during inertia welding occurred predominantly on the nickel base alloy side. It was also noted that at least some degree of forging on the refractory metal side of the joint was necessary to achieve consistent bonding. Both refractory metals were readily weldable to the Hastelloy X material. When bonding to the MarM 247, results were inconsistent. This was related to the higher forging temperatures of the MarM 247, and subsequent reduced deformation on that material during welding. ESD trials using a Hastelloy X filler were successful for all material combinations. ESD places down very thin (5- to 10- m) layers per pass, and interactions between the substrates and the fill were limited (at most) to that layer. For the refractory metals, the fill only appeared to wet the surface, with minimal dilution effects. Microstructures of the deposits showed high weld metal integrity with maximum porosity on the order of a few percent. Some limited success was also obtained with MPW. In these trials, only the T-111 tubes were used. Joints were possible for the T-111 tube to the Hastelloy X bar stock, but the stiffness of the tube (resisting collapse) necessitated the use of very high power levels. These power levels

  20. Nanoscaled tin dioxide films processed from organotin-based hybrid materials: an organometallic route toward metal oxide gas sensors.

    PubMed

    Renard, Laetitia; Babot, Odile; Saadaoui, Hassan; Fuess, Hartmut; Brötz, Joachim; Gurlo, Aleksander; Arveux, Emmanuel; Klein, Andreas; Toupance, Thierry

    2012-11-07

    Nanocrystalline tin dioxide (SnO(2)) ultra-thin films were obtained employing a straightforward solution-based route that involves the calcination of bridged polystannoxane films processed by the sol-gel process from bis(triprop-1-ynylstannyl)alkylene and -arylene precursors. These films have been thoroughly characterized by FTIR, contact angle measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force (AFM) and scanning electron (SEM) microscopies. Annealing at a high temperature gave 30-35 nm thick cassiterite SnO(2) films with a mean crystallite size ranging from 4 to 7 nm depending on the nature of the organic linker in the distannylated compound used as a precursor. In the presence of H(2) and CO gases, these layers led to highly sensitive, reversible and reproducible responses. The sensing properties were discussed in regard to the crystallinity and porosity of the sensing body that can be tuned by the nature of the precursor employed. Organometallic chemistry combined with the sol-gel process therefore offers new possibilities toward metal oxide nanostructures for the reproducible and sensitive detection of combustible and toxic gases.

  1. Convergent study of Ru-ligand interactions through QTAIM, ELF, NBO molecular descriptors and TDDFT analysis of organometallic dyes

    NASA Astrophysics Data System (ADS)

    Sánchez-Coronilla, Antonio; Sánchez-Márquez, Jesús; Zorrilla, David; Martín, Elisa I.; de los Santos, Desireé M.; Navas, Javier; Fernández-Lorenzo, Concha; Alcántara, Rodrigo; Martín-Calleja, Joaquín

    2014-08-01

    We report a theoretical study of a series of Ru complexes of interest in dye-sensitised solar cells, in organic light-emitting diodes, and in the war against cancer. Other metal centres, such as Cr, Co, Ni, Rh, Pd, and Pt, have been included for comparison purposes. The metal-ligand trends in organometallic chemistry for those compounds are shown synergistically by using three molecular descriptors: quantum theory of atoms in molecules (QTAIM), electron localisation function (ELF) and second-order perturbation theory analysis of the natural bond orbital (NBO). The metal-ligand bond order is addressed through both delocalisation index (DI) of QTAIM and fluctuation index (λ) of ELF. Correlation between DI and λ for Ru-N bond in those complexes is introduced for the first time. Electron transfer and stability was also assessed by the second-order perturbation theory analysis of the NBO. Electron transfer from the lone pair NBO of the ligands toward the antibonding lone pair NBO of the metal plays a relevant role in stabilising the complexes, providing useful insights into understanding the effect of the 'expanded ligand' principle in supramolecular chemistry. Finally, absorption wavelengths associated to the metal-to-ligand charge transfer transitions and the highest occupied molecular orbital (HOMO)--lowest unoccupied molecular orbital (LUMO) characteristics were studied by time-dependent density functional theory.

  2. The Development and Study of Surface Bound Ruthenium Organometallic Complexes

    NASA Astrophysics Data System (ADS)

    Abbott, Geoffrey Reuben

    The focus of this project has been on the use of mono-diimine ruthenium organometallic complexes, of the general structure [H(Ru)(CO)(L)2(L') 2][PF6] (L=PPh3, DPPENE and L'=Bpy, DcBpy, MBpyC, Phen, AminoPhen) bound to surfaces as luminescent probes. Both biological and inorganic/organic hybrid surfaces have been studied. The complexes were characterized both bound and unbound using standard analytical techniques such as NMR, IR and X-ray crystallography, as well as through several photophysical methods as well. Initially the study focused on how the photophyscial properties of the complexes were affected by incorporation into biological membranes. It was found that by conjugating the probes to a more rigid cholesterol moiety that luminescence was conserved, compared to conjugation with a far more flexible lipid moiety, where luminescence was either lost or reduced. Both the cholesterol and lipid conjugates were able to insert into a lipid membrane, and in the more rigid environment some of the lipid conjugates regained some of their luminescence, but often blue shifted and reduced, depending on the conjugation site. Silica Polyamine Composites (SPCs) were a hybrid material developed in the Rosenberg Lab as useful metal separation materials, that could be easily modified, and had several benefits over current commercially available polymers, or inorganic materials. These SPCs also provided an opportunity for the development of a heterogeneous platform for luminescent complexes as either catalysts or sensors. Upon binding of the luminescent Ru complexes to the surface no loss, or major change in luminescence was seen, however, when bound to the rigid surface a significant increase in excited state lifetime was measured. It is likely that through binding and interacting with the surface that the complexes lost non-radiative decay pathways, resulting in the increase in lifetime, however, these interactions do not seem to affect the energy level of the MLCT band in a

  3. Desulfurization of Ni-based super alloys by combined heating and glow discharge

    SciTech Connect

    Outlaw, R.A.; Rezaie-Serej, S.; Allen, W.P.; Latanision, R.M.

    1996-04-15

    The service lifetime of blades and vanes in aircraft gas turbines can be influenced by the degradation of the interface of the Ni-based superalloy and the overlying aluminide coating during cyclic oxidation. Advanced superalloys and coatings rely on formation of a thin and continuous Al{sub 2}O{sub 3} film to protect the base alloy from further oxidative attack at temperatures above 980 C. In order that the Al{sub 2}O{sub 3} scale be protective, it must remain adherent to the underlying alloy under thermal cycling conditions. Recent experimental work indicates that the interfacial binding between Ni and the overlying Al{sub 2}O{sub 3} scale is initially strong, but has also been shown that segregation of indigenous sulfur to the metal/oxide interface induces premature scale spallation, apparently through a reduction in the interfacial adhesive strength with a concomitant reduction in component lifetime. Removal of the sulfur is the best solution to this problem.

  4. Resistance to sulfur poisoning of Ni-based alloy with coinage (IB) metals

    NASA Astrophysics Data System (ADS)

    Xu, Xiaopei; Zhang, Yanxing; Yang, Zongxian

    2015-12-01

    The poisoning effects of S atom on the (1 0 0), (1 1 0) and (1 1 1) metal surfaces of pure Ni and Ni-based alloy with IB (coinage) metals (Cu, Ag, Au) are systematically studied. The effects of IB metal dopants on the S poisoning features are analyzed combining the density functional theory (DFT) results with thermodynamics data using the ab initio atomistic thermodynamic method. It is found that introducing IB doping metals into Ni surface can shift the d-band center downward from the Fermi level and weaken the adsorption of S on the (1 0 0) and (1 1 0) surfaces, and the S tolerance ability increases in the order of Ni, Cu/Ni, Ag/Ni and Au/Ni. Nevertheless, on the (1 1 1) surface, the S tolerance ability increases in the order of Ag/Ni (or Cu/Ni), Ni, and Au/Ni. When we increase the coverage of the IB metal dopants, we found that not only Au, but Cu and Ag can increase its S tolerance. We therefore propose that alloying can increase its S tolerance and alloying with Au would be a better way to increase the resistance to sulfur poisoning of the Ni anode as compared with the pure Ni and the Ag- or, Cu-doped Ni materials.

  5. Hot Deformation Processing Map and Microstructural Evaluation of the Ni-Based Superalloy IN-738LC

    NASA Astrophysics Data System (ADS)

    Sajjadi, S. A.; Chaichi, A.; Ezatpour, H. R.; Maghsoudlou, A.; Kalaie, M. A.

    2016-04-01

    Hot deformation behavior of the Ni-based superalloy IN-738LC was investigated by means of hot compression tests over the temperature range of 1000-1200 °C and strain rate range of 0.01-1 s-1. The obtained peak flow stresses were related to strain rate and temperature through the hyperbolic sine equation with activation energy of 950 kJ/mol. Dynamic material model was used to obtain the processing map of IN-738LC. Analysis of the microstructure was carried out in order to study each domain's characteristic represented by the processing map. The results showed that dynamic recrystallization occurs in the temperature range of 1150-1200 °C and strain rate of 0.1 s-1 with the maximum power dissipation efficiency of 35%. The unstable domain was exhibited in the temperature range of 1000-1200 °C and strain rate of 1 s-1 on the occurrence of severe deformation bands and grain boundary cracking.

  6. A study of microstructural characteristics of Ni-based superalloys at high temperatures

    NASA Technical Reports Server (NTRS)

    Lal, R. B.; Aggarwal, M. D.

    1988-01-01

    The microstructural characteristics of the Ni-based superalloy MAR-M246(Hf) which is used in manufacturing the components of the Space Shuttle's main engine have been studied. These superalloys need optimal heat treatment to get the best results. To find the optimum heat treatment the technique of differential thermal analysis and the optical photomicrographs are being planned to be utilized. In the first phase, the existing experimental equipment like cutting, grinding/polishing machines and metallurgical microscope have been set up to cut/polish and take the photomicrographs. In the beginning of this year an order was placed for the Leitz Mettalux-3 microscope with a hot stage for in-situ observation of the superalloy samples. The hot stage was tested for the first time, alloying the thermocouple with the Tantulum heating element and has not been installed finally by the supplier. A Perkin Elmer Differential Thermal Analyzer (DTA 1700) was procured in the first year of the project. Samples of MAR-M246(Hf), MAR-M247, Waspaloy, Udimet-41, CMSX-2 and CMSX-3 (polycrystalline and single crystals) have been studied using differential thermal analyzer.

  7. Kinetics and Mechanisms of γ‧ Reprecipitation in a Ni-based Superalloy

    NASA Astrophysics Data System (ADS)

    Masoumi, F.; Shahriari, D.; Jahazi, M.; Cormier, J.; Devaux, A.

    2016-06-01

    The reprecipitation mechanisms and kinetics of γ‧ particles during cooling from supersolvus and subsolvus temperatures were studied in AD730TM Ni-based superalloy using Differential Thermal Analysis (DTA). The evolution in the morphology and distribution of reprecipitated γ‧ particles was investigated using Field Emission Gun Scanning Electron Microscopy (FEG-SEM). Depending on the cooling rate, γ‧ particles showed multi or monomodal distribution. The irregularity growth characteristics observed at lower cooling rates were analyzed in the context of Mullins and Sekerka theory, and allowed the determination of a critical size of γ‧ particles above which morphological instability appears. Precipitation kinetics parameters were determined using a non-isothermal JMA model and DTA data. The Avrami exponent was determined to be in the 1.5–2.3 range, suggesting spherical or irregular growth. A methodology was developed to take into account the temperature dependence of the rate coefficient k(T) in the non-isothermal JMA equation. In that regard, a function for k(T) was developed. Based on the results obtained, reprecipitation kinetics models for low and high cooling rates are proposed to quantify and predict the volume fraction of reprecipitated γ‧ particles during the cooling process.

  8. Influence of coarsened and rafted microstructures on the thermomechanical fatigue of a Ni-base superalloy

    DOE PAGES

    Kirka, M. M.; Brindley, K. A.; Neu, R. W.; ...

    2015-08-17

    The aging of the microstructure of Ni-base superalloys during service is mainly characterized by coarsening and rafting of the γ' precipitates. The influence of these different aged microstructures on thermomechanical fatigue (TMF) under either continuously cycled (CC) and creep-fatigue (CF) was investigated. Three different aged microstructures, generated through accelerated aging and pre-creep treatments, were studied: stress-free coarsened γ', rafted with orientation perpendicular to loading direction (N-raft), and rafted with orientation parallel to loading direction (P-raft). Under most conditions, the aged microstructures were less resistant to TMF than the virgin microstructure; however, there were exceptions. Both stress-free coarsened and N-raft microstructuresmore » resulted in a reduction in TMF life under both CC and CF conditions in comparison to the virgin material. P-raft microstructure also resulted in reduction in TMF life under CC conditions; however, an increase in life over that of the virgin material was observed under CF conditions. Finally, these differences are discussed and hypothesized to be related to the interactions of the dislocations in the γ channels with γ' precipitates.« less

  9. Influence of coarsened and rafted microstructures on the thermomechanical fatigue of a Ni-base superalloy

    SciTech Connect

    Kirka, M. M.; Brindley, K. A.; Neu, R. W.; Antolovich, S. D.; Shinde, S. R.; Gravett, P. W.

    2015-08-17

    The aging of the microstructure of Ni-base superalloys during service is mainly characterized by coarsening and rafting of the γ' precipitates. The influence of these different aged microstructures on thermomechanical fatigue (TMF) under either continuously cycled (CC) and creep-fatigue (CF) was investigated. Three different aged microstructures, generated through accelerated aging and pre-creep treatments, were studied: stress-free coarsened γ', rafted with orientation perpendicular to loading direction (N-raft), and rafted with orientation parallel to loading direction (P-raft). Under most conditions, the aged microstructures were less resistant to TMF than the virgin microstructure; however, there were exceptions. Both stress-free coarsened and N-raft microstructures resulted in a reduction in TMF life under both CC and CF conditions in comparison to the virgin material. P-raft microstructure also resulted in reduction in TMF life under CC conditions; however, an increase in life over that of the virgin material was observed under CF conditions. Finally, these differences are discussed and hypothesized to be related to the interactions of the dislocations in the γ channels with γ' precipitates.

  10. Investigations of White Layer Formation During Machining of Powder Metallurgical Ni-Based ME 16 Superalloy

    NASA Astrophysics Data System (ADS)

    Veldhuis, S. C.; Dosbaeva, G. K.; Elfizy, A.; Fox-Rabinovich, G. S.; Wagg, T.

    2010-10-01

    Surface integrity of machined parts made from the advanced Ni-based superalloys is important for modern manufacturing in the aerospace industry. Metallographic observations of the ME 16 alloy microstructure were made using optical metallography and a high-resolution scanning electron microscope with energy dispersive x-ray spectrometer (HR SEM/EDS). Tool life of cemented carbide inserts with TiAlN coating during machining (finishing turning operation) of ME 16 superalloy has been studied and wear patterns of the cutting tools were identified. Surface integrity of the machined part after completion of the turning operation was investigated. The morphology of machined parts has been examined and cross-sections of the machined surfaces have been analyzed. The formation of white layer on the surface of the machined part was studied for varied machining conditions. It was found that a 2-4 µm thick white layer forms during turning of the ME 16 superalloy. This layer was investigated using EDS and XRD. The studies show that the white layer is an oxygen-containing layer with a high amount of aluminum, enriched by chromium and tungsten. Under specific cutting conditions, the structure of white layer transforms into a γ-alumina. Formation of this thermal barrier ceramic white layer on the surface of the machined part negatively affects its surface integrity and cutting tool life.

  11. Control of Interfacial Reactivity Between ZrB2 and Ni-Based Brazing Alloys

    NASA Astrophysics Data System (ADS)

    Valenza, F.; Muolo, M. L.; Passerone, A.; Cacciamani, G.; Artini, C.

    2012-05-01

    Transition metals diborides (Ti,Zr,Hf)B2 play a key role in applications where stability at extremely high temperatures and damage tolerance are required; however, much research has still to be done to optimize the joining of these materials to themselves or to other high-temperature materials. In this study, the reactivity at the solid-liquid interface between ZrB2 ceramics and Ni-based brazing alloys has been addressed; it is shown how the reactivity and the dissolution of the solid phase can be controlled and even suppressed by adjusting the brazing alloy composition on the basis of thermodynamic calculations. Wetting experiments on ZrB2 ceramics by Ni, Ni-B 17 at.%, and Ni-B 50 at.% were performed at 1500 and 1200 °C by the sessile drop technique. The obtained interfaces were characterized by optical microscopy and SEM-EDS, and interpreted by means of the ad hoc-calculated B-Ni-Zr ternary diagram. A correlation among microstructures, substrate dissolution, shape of the drops, spreading kinetics, and the phase diagram was found. The effect on the interfacial reactivity of Si3Ni4 used as a sintering aid and issues related to Si diffusion into the brazing alloy are discussed as well.

  12. Burner Rig Hot Corrosion of Five Ni-Base Alloys Including Mar-M247

    NASA Technical Reports Server (NTRS)

    Nesbitt, James A.; Helmink, R.; Harris, K.; Erickson, G.

    2000-01-01

    The hot corrosion resistance of four new Ni-base superalloys was compared to that of Mar-M247 by testing in a Mach 0.3 burner rig at 900 C for 300 1-hr cycles. While the Al content was held the same as in the Mar-M247, the Cr and Co levels in the four new alloys were decreased while other strengthening elements (Re, Ta) were increased. Surprisingly, despite their lower Cr and Co contents, the hot corrosion behavior of all four new alloys was superior to that of the Mar-M247 alloy. The Mar-M247 alloy began to lose weight almost immediately whereas the other four alloys appeared to undergo an incubation period of 50-150 1-hr cycles. Examination of the cross-sectional microstructures showed regions of rampant corrosion attack (propagation stage) in all five alloys after 300 1-hr cycles . This rampant corrosion morphology was similar for each of the alloys with Ni and Cr sulfides located in an inner subscale region. The morphology of the attack suggests a classic "Type I", or high temperature, hot corrosion attack.

  13. Kinetics and Mechanisms of γ′ Reprecipitation in a Ni-based Superalloy

    PubMed Central

    Masoumi, F.; Shahriari, D.; Jahazi, M.; Cormier, J.; Devaux, A.

    2016-01-01

    The reprecipitation mechanisms and kinetics of γ′ particles during cooling from supersolvus and subsolvus temperatures were studied in AD730TM Ni-based superalloy using Differential Thermal Analysis (DTA). The evolution in the morphology and distribution of reprecipitated γ′ particles was investigated using Field Emission Gun Scanning Electron Microscopy (FEG-SEM). Depending on the cooling rate, γ′ particles showed multi or monomodal distribution. The irregularity growth characteristics observed at lower cooling rates were analyzed in the context of Mullins and Sekerka theory, and allowed the determination of a critical size of γ′ particles above which morphological instability appears. Precipitation kinetics parameters were determined using a non-isothermal JMA model and DTA data. The Avrami exponent was determined to be in the 1.5–2.3 range, suggesting spherical or irregular growth. A methodology was developed to take into account the temperature dependence of the rate coefficient k(T) in the non-isothermal JMA equation. In that regard, a function for k(T) was developed. Based on the results obtained, reprecipitation kinetics models for low and high cooling rates are proposed to quantify and predict the volume fraction of reprecipitated γ′ particles during the cooling process. PMID:27338868

  14. Electron phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    DOE PAGES

    Samolyuk, German D.; Stocks, George Malcolm; Stoller, Roger E.

    2016-04-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states atmore » the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration.« less

  15. Laser surface annealing of Ni-base superalloy for enhancement of material performance in hydrogen environment

    NASA Astrophysics Data System (ADS)

    Hirose, Akio; Liu, Liufa; Kobayashi, Kojiro F.

    2000-11-01

    In the present work, laser surface annealing has been applied to an age-hardened Ni base supper alloy Inconel 718 using a 2.5kW CO2 laser to improve its performance in hydrogen environment. Laser surface annealing can produce a locally solutionized zone at the surface of Inconel 718. In the solutionized zone the age precipitates of (gamma) ' and (gamma) '' are dissolved in the matrix, and thereby the hardness of the solutionized zones is reduced to below 250Hv from approximately 450Hv of the aged base metal hardness. The surface softened zones having several hundred micro meters in depth can be obtained without melting the treated zone by controlling the laser parameters, i.e. thee defocus distance and traverse speed. Having much greater ductility than the aged base metal in hydrogen environment, the surface softened zones can effectively prevent hydrogen induced cracking, which tends to occur at the surface of a stress concentrated region. In the present case, the ductility of the surface annealed specimen is almost twice that of the base metal in a tensile test under a 29.3MPa hydrogen atmosphere at room temperature with hydrogen pre- charging. Since a controlled laser irradiation can precisely and locally anneal the surface of a stress concentrated region where hydrogen induced cracking is liable to occur, a sacrifice of strength of the structure caused by the surface softening is negligible.

  16. Crystallization behavior of a melt-spun Fe-Ni based steel

    NASA Technical Reports Server (NTRS)

    Michal, G. M.; Laxmanan, V.; Glasgow, T. K.

    1987-01-01

    Whether Fe-Ni-based alloys solidify with a bcc or fcc structure has been observed by many investigators to be a stronger function of kinetics and undercooling than strictly free-energy minimization. Such behavior has been observed in an Fe(52.8)Ni(28.7)Al(3.4)Ti(6.1)B(9.0) alloy. The alloy was cast as ribbons about 45 microns thick using a dual free-jet variation of chillbock melt spinning against a Cu wheel. Optical, X-ray, and electron analyses of the as-cast and annealed ribbons were performed. A microstructure of at least four layers containing combinations of ecc, bcc, and amorphous phases in differing proportions was observed in the as-cast ribbon. The midthickness layer had the most unusual features, containing fcc grains about 75 nm in size encompassing spherulitic regions as large as 15 microns comprised of fcc grains about 25 nm in size. The crystallization sequence responsible for the as-cast microstructure is discussed in terms of the competition between the formation of bcc and fcc phases as influenced by undercooling, recalescence, and variations in cooling rate experienced by the as-cast ribbon.

  17. Atomic-scale properties of Ni-based FCC ternary, and quaternary alloys

    DOE PAGES

    Tamm, Artur; Aabloo, Alvo; Klintenberg, Mattias; ...

    2015-08-26

    The aim of our study is to characterize some atomic-scale properties of Ni-based FCC multicomponent alloys. For this purpose, we use Monte Carlo method combined with density functional theory calculations to study short-range order (SRO), atomic displacements, electronic density of states, and magnetic moments in equimolar ternary NiCrCo, and quaternary NiCrCoFe alloys. The salient features for the ternary alloy are a negative SRO parameter between Ni Cr and a positive between Cr Cr pairs as well as a weakly magnetic state. For the quaternary alloy we predict negative SRO parameter for Ni Cr and Ni Fe pairs and positive formore » Cr Cr and Fe Fe pairs. Atomic displacements for both ternary and quaternary alloys are negligible. In contrast to the ternary, the quaternary alloy shows a complex magnetic structure. The electronic structure of the ternary and quaternary alloys shows differences near the Fermi energy between a random solid solution and the predicted structure with SRO. Despite that, the calculated EXAFS spectra does not show enough contrast to discriminate between random and ordered structures. Finally, the predicted SRO has an impact on point-defect energetics, electron phonon coupling and thermodynamic functions and thus, SRO should not be neglected when studying properties of these two alloys.« less

  18. Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals

    SciTech Connect

    Michael J. Mills

    2009-03-05

    Cast nickel-based superalloys are used for blades in land-based, energy conversion and powerplant applications, as well as in aircraft gas turbines operating at temperatures up to 1100 C, where creep is one of the life-limiting factors. Creep of superalloy single crystals has been extensively studied over the last several decades. Surprisingly, only recently has work focused specifically on the dislocation mechanisms that govern high temperature and low stress creep. Nevertheless, the perpetual goal of better engine efficiency demands that the creep mechanisms operative in this regime be fully understood in order to develop alloys and microstructures with improved high temperature capability. At present, the micro-mechanisms controlling creep before and after rafting (the microstructure evolution typical of high temperature creep) has occurred have yet to be identified and modeled, particularly for [001] oriented single crystals. This crystal orientation is most interesting technologically since it exhibits the highest creep strength. The major goal of the program entitled ''Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals'' (DOE Grant DE-FG02-04ER46137) has been to elucidate these creep mechanisms in cast nickel-based superalloys. We have utilized a combination of detailed microstructure and dislocation substructure analysis combined with the development of a novel phase-field model for microstructure evolution.

  19. The Portevin-Le Chatelier Effect in the Ni-Based Superalloy IN100

    NASA Astrophysics Data System (ADS)

    Fernandez-Zelaia, Patxi; Adair, Benjamin S.; Barker, Vincent M.; Antolovich, Stephen D.

    2015-12-01

    The Portevin-Le Chatelier (PLC) effect has been studied in the Ni-based superalloy IN100 which is currently used as a disk material in jet engines. A series of tensile tests was carried out at 588 K, 755 K, and 922 K (315 °C, 482 °C, and 649 °C) at plastic strain rates ranging from a low of 6.21 × 10-6 s-1 to a high of 4.92 × 10-2 s-1. The activation energy was determined using the slope of a line on a strain rate/temperature graph which divided the area of the graph into two regions: (1) "PLC behavior observed," and (2) "No PLC behavior observed." A new statistical approach was developed to objectively differentiate between a true PLC effect and experimental uncertainty ( i.e., "noise"). The value of the activation energy was found to be 1.14 eV/atom, which strongly suggests that the rate controlling process was bulk diffusion of C in the lattice. A qualitative model, based on the Orowan equation and slip band dislocation mechanics, was proposed, which unifies the seemingly disparate ideas of the process being controlled by a single atom/dislocation interaction while at the same time exhibiting significant strains during PLC load drops.

  20. Local Evolution of the Elastocaloric Effect in TiNi-Based Films

    NASA Astrophysics Data System (ADS)

    Ossmer, H.; Chluba, C.; Gueltig, M.; Quandt, E.; Kohl, M.

    2015-06-01

    Strain and temperature profiles of magnetron-sputtered ferroelastic TiNi-based films of 20 μm thickness are investigated during tensile load cycling with respect to strain, strain rate, and cycle number in order to assess their potential for elastocaloric cooling. Two different ferroelastic film specimens are considered, binary TiNi and quaternary TiNiCuCo films, which strongly differ regarding their phase transformation hysteresis and fatigue behavior. In situ digital image correlation and infrared thermography measurements reveal a correlated response of strain and temperature bands that is determined by mesoscale stress and temperature fields on the kinetics of phase transformation. In the case of binary TiNi films, this response is also strongly affected by cycling-induced fatigue causing vanishing band formation and decreasing elastocaloric effect size. In contrast, TiNiCuCo films show negligible fatigue and retain the local characteristics of the elastocaloric effect. Compared to TiNi films, they exhibit not only a reduced temperature change, but also a reduced work input for pseudoelastic cycling resulting in an improved material's coefficient of performance of 15.

  1. Atomic-scale properties of Ni-based FCC ternary, and quaternary alloys

    SciTech Connect

    Tamm, Artur; Aabloo, Alvo; Klintenberg, Mattias; Stocks, Malcolm; Caro, Alfredo

    2015-08-26

    The aim of our study is to characterize some atomic-scale properties of Ni-based FCC multicomponent alloys. For this purpose, we use Monte Carlo method combined with density functional theory calculations to study short-range order (SRO), atomic displacements, electronic density of states, and magnetic moments in equimolar ternary NiCrCo, and quaternary NiCrCoFe alloys. The salient features for the ternary alloy are a negative SRO parameter between Ni Cr and a positive between Cr Cr pairs as well as a weakly magnetic state. For the quaternary alloy we predict negative SRO parameter for Ni Cr and Ni Fe pairs and positive for Cr Cr and Fe Fe pairs. Atomic displacements for both ternary and quaternary alloys are negligible. In contrast to the ternary, the quaternary alloy shows a complex magnetic structure. The electronic structure of the ternary and quaternary alloys shows differences near the Fermi energy between a random solid solution and the predicted structure with SRO. Despite that, the calculated EXAFS spectra does not show enough contrast to discriminate between random and ordered structures. Finally, the predicted SRO has an impact on point-defect energetics, electron phonon coupling and thermodynamic functions and thus, SRO should not be neglected when studying properties of these two alloys.

  2. Microstructure evolution and mechanical property of pulsed laser welded Ni-based superalloy

    NASA Astrophysics Data System (ADS)

    Ma, Guangyi; Wu, Dongjiang; Niu, Fangyong; Zou, Helin

    2015-09-01

    For evaluating the microstructure evolution and mechanical property of Ni-based Hastelloy C-276 weld joint by the pulsed laser welding, the influence of pulsed laser welding on the microstructure and mechanical property of the weld joint is investigated by the analysis of the microstructure morphology, microhardness, phase structure and tensile property. The results indicate that, in the fusion zone three sections are divided on the basis of the patterns of grain structures. In the weld joint, the element segregation is found, but the trend of brittle phase's formation is weakened. The weld microhardness presents just a little higher than that of base metal, and there is no obvious the softened heat affected zone. Meanwhile in the weld joint, the phase structure is still the face-center cubic with the tiny shift of peak positions and widened Full Width at Half-Maximum. The yield strength of weld joint is the same as that of base metal, and the tensile strength is nearly 90% of that of base metal. The decreased tensile strength is mainly attributed to the dislocation piling-up.

  3. Synthesis and Characterization of Neopentylaluminum Compounds.

    DTIC Science & Technology

    1987-08-05

    Mols, 0. ]lsley, W. H.; Oliver, J. P. Organometallics 1286, 1, 1812. 3. Lehmkuhl, H. Justus Liebigs Ann. Chem. 168, 719, 40. 4. Nyathl, J. Z.; Ressner...Manipulation of Air-Sensitive Compounds" John Wiley & Sons, New York, 1986, p 38. 10. Pfohl, W. Justus Liebigs Ann. Chem . 1260, 629, 207. 11. Hoffmann, E...G. Justus Liebigs Ann. Chem. 1260, 629, 104. 12. Malpass, D. B.; Watson, S. C. U. S. Patents 4,170,604 and 4,101,568. 13. Pitzer, K. S.; Gutowsky, H

  4. (Comparison of group transfer, inner sphere and outer sphere electron transfer mechanisms of organometallic complexes)

    SciTech Connect

    Atwood, J.

    1990-01-01

    During the course of Grant ER13775 we have constructed an infrared stopped-flow spectrophotometer and initiated a study of the mechanisms of reactions that involve a change in the oxidation state of organometallic complexes. The spectrometer combined conventional stopped-flow techniques with an infrared optical system comprised of a carbon monoxide laser, an IRTRAN flow-through cell and a mercury-cadium-telluride detector. In this summary we will highlight our results on reactions: (1) that formally involve exchange of a charged species between two metal carbonyl anions, (2) that involve additional of an electron to, or removal of an electron from organometallic complexes that contain a metal-metal bond, and (3) between coordination complexes and metal carbonyl anions. 12 refs.

  5. Antimicrobial Organometallic Dendrimers with Tunable Activity against Multidrug-Resistant Bacteria.

    PubMed

    Abd-El-Aziz, Alaa S; Agatemor, Christian; Etkin, Nola; Overy, David P; Lanteigne, Martin; McQuillan, Katherine; Kerr, Russell G

    2015-11-09

    Multidrug-resistant pathogens are an increasing threat to public health. In an effort to curb the virulence of these pathogens, new antimicrobial agents are sought. Here we report a new class of antimicrobial organometallic dendrimers with tunable activity against multidrug-resistant Gram-positive bacteria that included methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium. Mechanistically, these redox-active, cationic organometallic dendrimers induced oxidative stress on bacteria and also disrupted the microbial cell membrane. The minimum inhibitory concentrations, which provide a quantitative measure of the antimicrobial activity of these dendrimers, were in the low micromolar range. AlamarBlue cell viability assay also confirms the antimicrobial activity of these dendrimers. Interestingly, these dendrimers were noncytotoxic to epidermal cell lines and to mammalian red blood cells, making them potential antimicrobial platforms for topical applications.

  6. Energy and chemicals from the selective electrooxidation of renewable diols by organometallic fuel cells.

    PubMed

    Bellini, Marco; Bevilacqua, Manuela; Filippi, Jonathan; Lavacchi, Alessandro; Marchionni, Andrea; Miller, Hamish A; Oberhauser, Werner; Vizza, Francesco; Annen, Samuel P; Grützmacher, H

    2014-09-01

    Organometallic fuel cells catalyze the selective electrooxidation of renewable diols, simultaneously providing high power densities and chemicals of industrial importance. It is shown that the unique organometallic complex [Rh(OTf)(trop2NH)(PPh3)] employed as molecular active site in an anode of an OMFC selectively oxidizes a number of renewable diols, such as ethylene glycol , 1,2-propanediol (1,2-P), 1,3-propanediol (1,3-P), and 1,4-butanediol (1,4-B) to their corresponding mono-carboxylates. The electrochemical performance of this molecular catalyst is discussed, with the aim to achieve cogeneration of electricity and valuable chemicals in a highly selective electrooxidation from diol precursors.

  7. Measuring grain boundary character distributions in Ni-base alloy 725 using high-energy diffraction microscopy

    DOE PAGES

    Bagri, Akbar; Hanson, John P.; Lind, J. P.; ...

    2016-10-25

    We use high-energy X-ray diffraction microscopy (HEDM) to characterize the microstructure of Ni-base alloy 725. HEDM is a non-destructive technique capable of providing three-dimensional reconstructions of grain shapes and orientations in polycrystals. The present analysis yields the grain size distribution in alloy 725 as well as the grain boundary character distribution (GBCD) as a function of lattice misorientation and boundary plane normal orientation. We find that the GBCD of Ni-base alloy 725 is similar to that previously determined in pure Ni and other fcc-base metals. We find an elevated density of Σ9 and Σ3 grain boundaries. We also observe amore » preponderance of grain boundaries along low-index planes, with those along (1 1 1) planes being the most common, even after Σ3 twins have been excluded from the analysis.« less

  8. Measuring grain boundary character distributions in Ni-base alloy 725 using high-energy diffraction microscopy

    SciTech Connect

    Bagri, Akbar; Hanson, John P.; Lind, J. P.; Kenesei, Peter; Suter, Robert; Gradecak, Silvija; Demkowicz, Michael J.

    2016-10-25

    We use high-energy X-ray diffraction microscopy (HEDM) to characterize the microstructure of Ni-base alloy 725. HEDM is a non-destructive technique capable of providing three-dimensional reconstructions of grain shapes and orientations in polycrystals. The present analysis yields the grain size distribution in alloy 725 as well as the grain boundary character distribution (GBCD) as a function of lattice misorientation and boundary plane normal orientation. We find that the GBCD of Ni-base alloy 725 is similar to that previously determined in pure Ni and other fcc-base metals. We find an elevated density of Σ9 and Σ3 grain boundaries. We also observe a preponderance of grain boundaries along low-index planes, with those along (1 1 1) planes being the most common, even after Σ3 twins have been excluded from the analysis.

  9. Measuring Grain Boundary Character Distributions in Ni-Base Alloy 725 Using High-Energy Diffraction Microscopy

    NASA Astrophysics Data System (ADS)

    Bagri, Akbar; Hanson, John P.; Lind, Jonathan; Kenesei, Peter; Suter, Robert M.; Gradečak, Silvija; Demkowicz, Michael J.

    2017-01-01

    We use high-energy X-ray diffraction microscopy (HEDM) to characterize the microstructure of Ni-base alloy 725. HEDM is a non-destructive technique capable of providing three-dimensional reconstructions of grain shapes and orientations in polycrystals. The present analysis yields the grain size distribution in alloy 725 as well as the grain boundary character distribution (GBCD) as a function of lattice misorientation and boundary plane normal orientation. We find that the GBCD of Ni-base alloy 725 is similar to that previously determined in pure Ni and other fcc-base metals. We find an elevated density of Σ9 and Σ3 grain boundaries. We also observe a preponderance of grain boundaries along low-index planes, with those along (1 1 1) planes being the most common, even after Σ3 twins have been excluded from the analysis.

  10. The halogen effect for Ni-base alloys - A new method for increasing the oxidation protection at high temperatures

    NASA Astrophysics Data System (ADS)

    Zschau, Hans-Eberhard; Renusch, Daniel; Masset, Patrick J.; Schütze, Michael

    2009-05-01

    A new method for oxidation protection of Ni-base alloys is presented. The method is based on the halogen effect. Thermodynamic calculations show the preferred formation of gaseous Al-halogenides within a certain region of fluorine partial pressures. Ion implantation has been chosen for fluorine treatment. The implantation parameters are defined by using the T-DYN simulation software. Based on these results fluorine implantations of the Ni-base alloy IN 738 are performed to meet the required fluorine content near the surface. The fluorine depth profiles are analyzed by using the PIGE-technique. After oxidation at 1050 °C a dense protecting external alumina scale is formed on the surface.

  11. Microstructure-Sensitive Extreme Value Probabilities for High Cycle Fatigue of Ni-Base Superalloy IN100 (Preprint)

    DTIC Science & Technology

    2009-03-01

    transition fatigue regimes; however, microplasticity (i.e., heterogeneous plasticity at the scale of microstructure) is relevant to understanding fatigue...and Socie [57] considered the affect of microplastic 14 Microstructure-Sensitive Extreme Value Probabilities for High Cycle Fatigue of Ni-Base...considers the local stress state as affected by intergranular interactions and microplasticity . For the calculations given below, the volumes over which

  12. The solid-state synthesis of metal nanoparticles from organometallic precursors.

    PubMed

    Wostek-Wojciechowska, Dorota; Jeszka, Jeremiasz K; Amiens, Catherine; Chaudret, Bruno; Lecante, Pierre

    2005-07-01

    Nanoparticles (NPs), average size of 2-5 nm, of ruthenium, cobalt, and rhodium have been prepared by an original method, namely the solid-state decomposition under dihydrogen of an organometallic precursor either dispersed in polymer films or directly as nanocrystals. The NPs dispersion, size, and morphology are investigated by transmission electron microscopy, and their structure by wide angle X-ray scattering. Infrared spectroscopy, after adsorption of carbon monoxide on the metal NPs surfaces, evidences a nonoxidized surface of high reactivity.

  13. Organometallic NLO Polymers. Accordian Main-Chain NLO Polymers of Ferrocene

    DTIC Science & Technology

    1991-12-13

    suggest that the reaction conditions required to carry out the Lewis acid catalyzed transesterification polycondensation are having deleterious effects on...organometallic main-chain NLO polymers. Our research 1"n -U has continued to f--cus on ferrocene based NLO polymers . MFP because of the outstanding results...under rt-ad pressure. The crude product wargood functional group tolerance because of the mild base (i.e. dissolved in chloroform and precipitated in

  14. Progress toward cascade cells made by OM-VPE. [organometallic vapor phase epitaxy

    NASA Technical Reports Server (NTRS)

    Borden, P. G.; Larue, R. A.; Ludowise, M. J.

    1982-01-01

    Organometallic Vapor Phase Epitaxy (COM-VPE) was used to make a sophisticated monolithic cascade cell, with a peak AMO efficiency of 16.6%, not corrected for 14% grid coverage. The cell has 9 epitaxial layers. The top cell is 1.35 microns thick with a 0.1 micron thich emitter. Both cells are heteroface n-p structures. The cascade cell uses metal interconnects. Details of growth and processing are described.

  15. Access to organometallic arylcobaltcorrins through radical synthesis: 4-ethylphenylcobalamin, a potential "antivitamin B(12)".

    PubMed

    Ruetz, Markus; Gherasim, Carmen; Gruber, Karl; Fedosov, Sergey; Banerjee, Ruma; Kräutler, Bernhard

    2013-02-25

    Locked B(12): 4-Ethylphenylcobalamin, a novel organometallic arylcobalamin, has been synthesized in a radical reaction. This vitamin B(12) antimetabolite features a strong Co-C bond, and represents a "locked" form of vitamin B(12) . It may be used in animal studies to induce functional vitamin B(12) deficiency artificially to help clarify still controversial issues related to the pathophysiology of vitamin B(12) deficiency.

  16. Molecular Models of Ruthenium(II) Organometallic Complexes

    ERIC Educational Resources Information Center

    Coleman, William F.

    2007-01-01

    This article presents the featured molecules for the month of March, which appear in the paper by Ozerov, Fafard, and Hoffman, and which are related to the study of the reactions of a number of "piano stool" complexes of ruthenium(II). The synthesis of compound 2a offers students an alternative to the preparation of ferrocene if they are only…

  17. Electron phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    SciTech Connect

    Samolyuk, German D.; Stocks, George Malcolm; Stoller, Roger E.

    2016-04-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states at the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration.

  18. Magnetic Properties of FeNi-Based Thin Film Materials with Different Additives.

    PubMed

    Liang, Cai; Gooneratne, Chinthaka P; Wang, Qing Xiao; Liu, Yang; Gianchandani, Yogesh; Kosel, Jurgen

    2014-09-01

    This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials attractive for sensor applications. Our findings show that FeNi deposited with Mo or Al yields magnetically soft materials and that depositing with B further increases the softness. The out-of-plane magnetic anisotropy of FeNi thin films is reduced by depositing with Al and completely removed by depositing with B. The effect of depositing with Mo is dependent on the Mo concentration. The coercivity of FeNiMo and FeNiAl is reduced to less than a half of that of FeNi, and a value as low as 40 A/m is obtained for FeNiB. The surfaces of the obtained FeNiMo, FeNiAl and FeNiB thin films reveal very different morphologies. The surface of FeNiMo shows nano-cracks, while the FeNiAl films show large clusters and fewer nano-cracks. When FeNi is deposited with B, a very smooth morphology is obtained. The crystal structure of FeNiMo strongly depends on the depositant concentration and changes into an amorphous structure at a higher Mo level. FeNiAl thin films remain polycrystalline, even at a very high concentration of Al, and FeNiB films are amorphous, even at a very low concentration of B.

  19. Magnetic Properties of FeNi-Based Thin Film Materials with Different Additives

    PubMed Central

    Liang, Cai; Gooneratne, Chinthaka P.; Wang, Qing Xiao; Liu, Yang; Gianchandani, Yogesh; Kosel, Jurgen

    2014-01-01

    This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials attractive for sensor applications. Our findings show that FeNi deposited with Mo or Al yields magnetically soft materials and that depositing with B further increases the softness. The out-of-plane magnetic anisotropy of FeNi thin films is reduced by depositing with Al and completely removed by depositing with B. The effect of depositing with Mo is dependent on the Mo concentration. The coercivity of FeNiMo and FeNiAl is reduced to less than a half of that of FeNi, and a value as low as 40 A/m is obtained for FeNiB. The surfaces of the obtained FeNiMo, FeNiAl and FeNiB thin films reveal very different morphologies. The surface of FeNiMo shows nano-cracks, while the FeNiAl films show large clusters and fewer nano-cracks. When FeNi is deposited with B, a very smooth morphology is obtained. The crystal structure of FeNiMo strongly depends on the depositant concentration and changes into an amorphous structure at a higher Mo level. FeNiAl thin films remain polycrystalline, even at a very high concentration of Al, and FeNiB films are amorphous, even at a very low concentration of B. PMID:25587418

  20. Gamma prime precipitation mechanisms and solute partitioning in Ni-base alloys

    NASA Astrophysics Data System (ADS)

    Rojhirunsakool, Tanaporn

    Nickel-base superalloys have been emerged as materials for gas turbines used for jet propulsion and electricity generation. The strength of the superalloys depends mainly from an ordered precipitates of L12 structure, so called gamma prime (gamma') dispersed within the disorder gamma matrix. The Ni-base alloys investigated in this dissertation comprise both model alloy systems based on Ni-Al-Cr and Ni-Al-Co as well as the commercial alloy Rene N5. Classical nucleation and growth mechanism dominates the gamma' precipitation process in slowed-cooled Ni-Al-Cr alloys. The effect of Al and Cr additions on gamma' precipitate size distribution as well as morphological and compositional development of gamma' precipitates were characterized by coupling transmission electron microscopy (TEM) and 3D atom probe (3DAP) techniques. Rapid quenching Ni-Al-Cr alloy experiences a non-classical precipitation mechanism. Structural evolution of the gamma' precipitates formed and subsequent isothermal annealing at 600 °C were investigated by coupling TEM and synchrotron-based high-energy xray diffraction (XRD). Compositional evolution of the non-classically formed gamma' precipitates was determined by 3DAP and Langer, Bar-on and Miller (LBM) method. Besides homogeneous nucleation, the mechanism of heterogeneous gamma' precipitation involving a discontinuous precipitation mechanism, as a function of temperature, was the primary focus of study in case of the Ni-Al-Co alloy. This investigation coupled SEM, SEM-EBSD, TEM and 3DAP techniques. Lastly, solute partitioning and enrichment of minor refractory elements across/at the gamma/ gamma' interfaces in the commercially used single crystal Rene N5 superalloy was investigated by using an advantage of nano-scale composition investigation of 3DAP technique.

  1. Effect of La2O3 Addition on Microstructure and Wear Behavior of Electrospark Deposited Ni-BASED Coatings

    NASA Astrophysics Data System (ADS)

    Yuxin, Gao; Jian, Yi

    2013-12-01

    La2O3 doped Ni-based coatings have been prepared by electrospark deposition technique. The effect of La2O3 on the microstructure, hardness and wear behavior of the as-prepared Ni-based coatings is investigated by using X-ray diffractometer, scanning electron microscope, wear tribometer and Vickers hardness tester. Results indicates that the microstructure, hardness and wear resistance of La2O3 doped Ni-based coatings are effectively improved as compared to the undoped one, and the coating with the addition of 2.5 wt.% La2O3 shows the optimal improvement effects. The addition of La2O3 can reduce the defects, refine grains and increase hardness of the coating, which can inhibit the nucleation and propagation of cracking, consequently resist cutting and fracture during the wear process. Moreover, the addition of La2O3 leads to changes in abrasion mechanism of the coatings, and the reasons resulting in different abrasion mechanisms are discussed.

  2. 2011 Organometallic Chemistry (July 10-15, 2011, Salve Regina University, Newport, RI)

    SciTech Connect

    Dr. Emilio Bunel

    2011-07-15

    Organometallic chemistry has played and will continue to play a significant role in helping us understand the way bonds are made or broken in the presence of a transition metal complex. Current challenges range from the efficient exploitation of energy resources to the creative use of natural and artificial enzymes. Most of the new advances in the area are due to our extended understanding of processes at a molecular level due to new mechanistic studies, techniques to detect reaction intermediates and theory. The conference will bring the most recent advances in the field including nanocatalysis, surface organometallic chemistry, characterization techniques, new chemical reactivity and theoretical approaches along with applications to organic synthesis and the discovery of new materials. The Conference will bring together a collection of investigators who are at the forefront of their field, and will provide opportunities for junior scientists and graduate students to present their work in poster format and exchange ideas with leaders in the field. Six outstanding posters will be selected for short talks. The collegial atmosphere of this Conference, with programmed discussion sessions as well as opportunities for informal gatherings in the afternoons and evenings, provides an avenue for scientists from different disciplines to brainstorm and promotes cross-disciplinary collaborations in the various research areas represented. Graduate students and postdoctoral fellows should also consider participating in the Gordon Research Seminar on Organometallic Chemistry (July 9-10, same location) which is specially designed to promote interaction and discussion between junior scientists.

  3. Investigation of organometallic reaction mechanisms with one and two dimensional vibrational spectroscopy

    SciTech Connect

    Cahoon, James Francis

    2008-12-01

    One and two dimensional time-resolved vibrational spectroscopy has been used to investigate the elementary reactions of several prototypical organometallic complexes in room temperature solution. The electron transfer and ligand substitution reactions of photogenerated 17-electron organometallic radicals CpW(CO)3 and CpFe(CO)2 have been examined with one dimensional spectroscopy on the picosecond through microsecond time-scales, revealing the importance of caging effects and odd-electron intermediates in these reactions. Similarly, an investigation of the photophysics of the simple Fischer carbene complex Cr(CO)5[CMe(OMe)] showed that this class of molecule undergoes an unusual molecular rearrangement on the picosecond time-scale, briefly forming a metal-ketene complex. Although time-resolved spectroscopy has long been used for these types of photoinitiated reactions, the advent of two dimensional vibrational spectroscopy (2D-IR) opens the possibility to examine the ultrafast dynamics of molecules under thermal equilibrium conditions. Using this method, the picosecond fluxional rearrangements of the model metal carbonyl Fe(CO)5 have been examined, revealing the mechanism, time-scale, and transition state of the fluxional reaction. The success of this experiment demonstrates that 2D-IR is a powerful technique to examine the thermally-driven, ultrafast rearrangements of organometallic molecules in solution.

  4. Synthesis of Some "Cobaloxime" Derivatives: A Demonstration of "Umpolung" in the Reactivity of an Organometallic Complex

    NASA Astrophysics Data System (ADS)

    Jameson, Donald L.; Grzybowski, Joseph J.; Hammels, Deb E.; Castellano, Ronald K.; Hoke, Molly E.; Freed, Kimberly; Basquill, Sean; Mendel, Angela; Shoemaker, William J.

    1998-04-01

    This article describes a four-reaction sequence for the synthesis of two organometallic "cobaloxime" derivatives. The concept of "Umpolung" or reversal of reactivity is demonstrated in the preparation of complexes. The complex Co(dmgH)2(4-t-BuPy)Et is formed by the reaction of a cobalt (I) intermediate (cobalt in the role of nucleophile) with ethyl iodide. The complex Co(dmgH)2(4-t-BuPy)Ph is formed by the reaction of PhMgBr with a cobalt (III) intermediate (cobalt in the role of electrophile). All the products contain cobalt in the diamagnetic +3 oxidation state and are readily characterized by proton and carbon NMR. The four reaction sequence may be completed in two 4-hour lab periods. Cobaloximes are well known as model complexes for Vitamin B-12 and the experiment exposes students to aspects of classical coordination chemistry, organometallic chemistry and bioinorganic chemistry. The experiment also illustrates an important reactivity parallel between organic and organometallic chemistry.

  5. Enhancing Sulfur Tolerance of Ni-Based Cermet Anodes of Solid Oxide Fuel Cells by Ytterbium-Doped Barium Cerate Infiltration.

    PubMed

    Li, Meng; Hua, Bin; Luo, Jing-Li; Jiang, San Ping; Pu, Jian; Chi, Bo; Li, Jian

    2016-04-27

    Conventional anode materials for solid oxide fuel cells (SOFCs) are Ni-based cermets, which are highly susceptible to deactivation by contaminants in hydrocarbon fuels. Hydrogen sulfide is one of the commonly existed contaminants in readily available natural gas and gasification product gases of pyrolysis of biomasses. Development of sulfur tolerant anode materials is thus one of the critical challenges for commercial viability and practical application of SOFC technologies. Here we report a viable approach to enhance substantially the sulfur poisoning resistance of a Ni-gadolinia-doped ceria (Ni-GDC) anode through impregnation of proton conducting perovskite BaCe0.9Yb0.1O3-δ (BCYb). The impregnation of BCYb nanoparticles improves the electrochemical performance of the Ni-GDC anode in both H2 and H2S containing fuels. Moreover, more importantly, the enhanced stability is observed in 500 ppm of H2S/H2. The SEM and XPS analysis indicate that the infiltrated BCYb fine particles inhibit the adsorption of sulfur and facilitate sulfur removal from active sites, thus preventing the detrimental interaction between sulfur and Ni-GDC and the formation of cerium sulfide. The preliminary results of the cell with the BCYb+Ni-GDC anode in methane fuel containing 5000 ppm of H2S show the promising potential of the BCYb infiltration approach in the development of highly active and stable Ni-GDC-based anodes fed with hydrocarbon fuels containing a high concentration of sulfur compounds.

  6. Investigation of porous Ni-based metal-organic frameworks containing paddle-wheel type inorganic building units via high-throughput methods.

    PubMed

    Maniam, Palanikumar; Stock, Norbert

    2011-06-06

    In the search of Ni based metal-organic frameworks (MOFs) containing paddle-wheel type building units, three chemical systems Ni(2+)/H(n)L/base/solvent with H(n)L = H(3)BTC (1,3,5-benzenetricarboxylic acid), H(3)BTB (4,4',4'',-benzene-1,3,5-triyl-tris(benzoic acid)), and H(2)BDC (terephthalic acid) were investigated using high-throughput (HT) methods. In addition to the conventional heating, for the first time HT microwave assisted synthesis of MOFs was carried out. Six new compounds were discovered, and their fields of formation were established. In the first system, H(3)BTC was employed and a comprehensive HT-screening of compositional and process parameters was conducted. The synthesis condition for the Ni paddle-wheel unit was determined and two compounds [Ni(3)(BTC)(2)(Me(2)NH)(3)]·(DMF)(4)(H(2)O)(4) (1a) and [Ni(6)(BTC)(2)(DMF)(6)(HCOO)(6)] (1b) were discovered (Me(2)NH = dimethylamine, DMF = dimethylformamide). In the second system, the use of the extended tritopic linker H(3)BTB and the synthesis conditions for the paddle-wheel units led to the porous MOF, [Ni(3)(BTB)(2)(2-MeIm)(1.5)(H(2)O)(1.5)]·(DMF)(9)(H(2)O)(6.5) (2), (2-MeIm = 2-methylimidazole). This compound shows a selective adsorption of H(2)O and H(2) with a strong hysteresis. In the third system, H(2)BDC was used, and the base (DABCO) was incorporated as a bridging ligand into all structures. Thus, two pillared layered porous MOFs [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(1.5) (3a) and [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(4) (3b) as well as a layered compound [Ni(BDC)(DABCO)]·(DMF)(1.5)(H(2)O)(2) (3c) were isolated. The 3a and 3b polymorphs of the [Ni(2)(BDC)(2)(DABCO)] framework can be selectively synthesized. The combination of microwave assisted heating, low overall concentration, stirring of the reaction mixtures, and an excess of DABCO yields a highly crystalline pure phase of 3b. The fields of formation of all compounds were established, and scale-up was successfully performed for 1b, 2

  7. Microstructure and corrosion resistance of Ni-based alloy laser coatings with nanosize CeO2 addition

    NASA Astrophysics Data System (ADS)

    Zhang, Shi Hong; Li, Ming Xi; Yoon, Jae Hong; Cho, Tong Yul; Zhu He, Yi; Lee, Chan Gyu

    2008-07-01

    Micron-size Ni-base alloy (NBA) powders were mixed with both 1.5 wt.% (hereinafter %) micron-size CeO2 (m-CeO2) and also 1.5% and 3.0% nano-size CeO2 (n- CeO2) powders. These mixtures were coated on low-carbon steel (Q235) by 2.0 kW CO2 laser cladding. The effects on the microstructures, phases and electrochemical corrosion of the coatings upon the addition of m- and n- CeO2 powders to NBA (m- and n- CeO2 /NBA) have been investigated. The results showed that a smooth coating was prepared under suitable processing parameters (P= 2.0 kW, V= 180 mm min- 1) by adding 1.5% n- CeO2. In addition to the primary phases of γ-Ni, Cr23 C6 and Ni3 B in the Ni-base alloy coating, CeNi3 was formed in Ni-base alloy coatings with both n- CeO2 and m-CeO2 particles, and CeNi5 appeared in the coating upon decreasing the size of CeO2 particles. Well-developed dendrites were observed in the Ni-base alloy coating; directional dendrites grew at the interface in the coating upon the addition of m-CeO2, whereas fine and multioriented dendrites grew upon decreasing the size of CeO2 particles to the nanoscale. Actinomorphic dendrites and compact equiaxed dendrites grew from the interface to near the surface upon increasing the content of n- CeO2 from 1.5 to 3.0%. In strongly acidic HNO3 solution, the severe corrosion of dendrites occurred and there were many corrosion pits in the Ni-base alloy coating; intercrystalline corrosion also has a dominant role upon the addition of m-CeO2, whereas uniform corrosion occurs in the coating as the size of CeO2 particles is decreased to nanoscale.

  8. Room temperature synthesis of Ni-based alloy nanoparticles by radiolysis.

    SciTech Connect

    Nenoff, Tina Maria; Berry, Donald T.; Lu, Ping; Leung, Kevin; Provencio, Paula Polyak; Stumpf, Roland Rudolph; Huang, Jian Yu; Zhang, Zhenyuan

    2009-09-01

    Room temperature radiolysis, density functional theory, and various nanoscale characterization methods were used to synthesize and fully describe Ni-based alloy nanoparticles (NPs) that were synthesized at room temperature. These complementary methods provide a strong basis in understanding and describing metastable phase regimes of alloy NPs whose reaction formation is determined by kinetic rather than thermodynamic reaction processes. Four series of NPs, (Ag-Ni, Pd-Ni, Co-Ni, and W-Ni) were analyzed and characterized by a variety of methods, including UV-vis, TEM/HRTEM, HAADF-STEM and EFTEM mapping. In the first focus of research, AgNi and PdNi were studied. Different ratios of Ag{sub x}- Ni{sub 1-x} alloy NPs and Pd{sub 0.5}- Ni{sub 0.5} alloy NP were prepared using a high dose rate from gamma irradiation. Images from high-angle annular dark-field (HAADF) show that the Ag-Ni NPs are not core-shell structure but are homogeneous alloys in composition. Energy filtered transmission electron microscopy (EFTEM) maps show the homogeneity of the metals in each alloy NP. Of particular interest are the normally immiscible Ag-Ni NPs. All evidence confirmed that homogeneous Ag-Ni and Pd-Ni alloy NPs presented here were successfully synthesized by high dose rate radiolytic methodology. A mechanism is provided to explain the homogeneous formation of the alloy NPs. Furthermore, studies of Pd-Ni NPs by in situ TEM (with heated stage) shows the ability to sinter these NPs at temperatures below 800 C. In the second set of work, CoNi and WNi superalloy NPs were attempted at 50/50 concentration ratios using high dose rates from gamma irradiation. Preliminary results on synthesis and characterization have been completed and are presented. As with the earlier alloy NPs, no evidence of core-shell NP formation occurs. Microscopy results seem to indicate alloying occurred with the CoNi alloys. However, there appears to be incomplete reduction of the Na{sub 2}WO{sub 4} to form the W

  9. MICROSTRUCTURE OF LONG-TERM AGED IN617 NI-BASE SUPERALLOY

    SciTech Connect

    Wu, Quanyan; Shingledecker, John P; Vasudevan, Vijay; Swindeman, Robert W

    2008-01-01

    The microstructure of the Ni-base superalloy IN617 that had undergone prolonged aging (approximately 65,000 hours) at a series of temperatures from 482 C to 871 C has been characterized by microhardness measurements, optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Cr23C6, Mo-rich eta-M6C, and Ti(C,N) constitute the major primary coarse precipitates both within the grains and along the grain boundaries. The secondary carbides were mostly fine Cr23C6, which had a cube-on-cube orientation relationship (OR) with the fcc matrix, and at long times were present in cuboidal and plate-shape forms within the grains and as films along the grain boundaries. Fine, eta-M6C carbides were also observed at low to intermediate temperatures with an OR given by [011] carbide//[011] matrix, carbide// matrix. The coarse eta-M6C carbides increased in extent at 871 C, whereas the counterpart fine carbides were absent. The phase was found to be present at all aging temperatures up to 871 C, with a volume fraction ranging from very low to approximately 5 pct at 593 C, where the peak in microhardness occurs. The observations have also suggested that the presence of a very small amount of at temperatures as high as 871 C at long times may be associated with a reaction between the fine eta-carbides and the matrix. Ultrafine precipitates of the intermetallic phase Ni2(Cr,Mo) with the Pt2Mo-type structure was observed in addition to in samples aged for 28,300 hours at the lowest aging temperature of 482 C. These precipitates were absent in samples aged at higher temperatures. The various observations made have suggested that the long-term thermal stability of the IN617 alloy is reasonably good over a wide temperature range of 538 C to 704 C, whereas at higher temperatures (871 C), the substantial decrease in the volume fraction of and coarsening and clustering of the carbides lead to a large drop in the microhardness. A modified time

  10. Subpicosecond reverse saturable absorption in organic and organometallic solutions

    NASA Astrophysics Data System (ADS)

    Pittman, M.; Plaza, P.; Martin, M. M.; Meyer, Y. H.

    1998-12-01

    Solutions of several carbocyanines, phthalocyanines and naphthalocyanines were studied by time-resolved transient spectroscopy with subpicosecond white-light continuum. The excited-state absorption cross-sections of all compounds were determined from the differential spectra obtained at short delay time after excitation, by a global spectral analysis. All these molecules exhibit an excited-state absorption cross-section higher than that of the ground state at 610 nm. This spectral property gives rise to a reverse saturable absorption (RSA) effect under high laser fluences at this wavelength. Nonlinear transmission of these molecules was measured under increasing laser fluences. A three-level molecular model was used to simulate the measured nonlinear transmission and the best fits were obtained with molecular parameters in good agreement with those deduced from the analysis of the transient spectra. The use of RSA for the energy stabilization of ultrashort laser pulses was demonstrated, and a stabilization coefficient was defined as an efficient tool for characterizing nonlinear behavior of such compounds.

  11. Organometallic rotaxane dendrimers with fourth-generation mechanically interlocked branches

    PubMed Central

    Wang, Wei; Chen, Li-Jun; Wang, Xu-Qing; Sun, Bin; Li, Xiaopeng; Zhang, Yanyan; Shi, Jiameng; Yu, Yihua; Zhang, Li; Liu, Minghua; Yang, Hai-Bo

    2015-01-01

    Mechanically interlocked molecules, such as catenanes, rotaxanes, and knots, have applications in information storage, switching devices, and chemical catalysis. Rotaxanes are dumbbell-shaped molecules that are threaded through a large ring, and the relative motion of the two components along each other can respond to external stimuli. Multiple rotaxane units can amplify responsiveness, and repetitively branched molecules—dendrimers—can serve as vehicles for assembly of many rotaxanes on single, monodisperse compounds. Here, we report the synthesis of higher-generation rotaxane dendrimers by a divergent approach. Linkages were introduced as spacer elements to reduce crowding and to facilitate rotaxane motion, even at the congested periphery of the compounds up to the fourth generation. The structures were characterized by 1D multinuclear (1H, 13C, and 31P) and 2D NMR spectroscopy, MALDI-TOF-MS, gel permeation chromatography (GPC), and microscopy-based methods including atomic force microscopy (AFM) and transmission electron microscopy (TEM). AFM and TEM studies of rotaxane dendrimers vs. model dendrimers show that the rotaxane units enhance the rigidity and reduce the tendency of these assemblies to collapse by self-folding. Surface functionalization of the dendrimers with ferrocenes as termini produced electrochemically active assemblies. The preparation of dendrimers with a well-defined topological structure, enhanced rigidity, and diverse functional groups opens previously unidentified avenues for the application of these materials in molecular electronics and materials science. PMID:25902491

  12. An Advanced Organometallic Lab Experiment with Biological Implications: Synthesis and Characterization of Fe[subscript 2](µ-S[subscript 2])(C0)[subscript 6

    ERIC Educational Resources Information Center

    Barrett, Jacob; Spentzos, Ariana; Works, Carmen

    2015-01-01

    The organometallic complex Fe[subscript 2](µ-S[subscript 2])(CO)[subscript 6] has interesting biological implications. The concepts of bio-organometallic chemistry are rarely discussed at the undergraduate level, but this experiment can start such a conversation and, in addition, teach valuable synthetic techniques. The lab experiment takes a…

  13. Organo-metallic elements for associative information processing

    NASA Astrophysics Data System (ADS)

    Potember, Richard S.; Poehler, Theodore O.

    1989-01-01

    In the three years of the program we have: (1) built and tested a 4 bit element matrix device for possible use in high density content-addressable memories systems; (2) established a test and evaluation laboratory to examine optical materials for nonlinear effects, saturable absorption, harmonic generation and photochromism; (3) successfully designed, constructed and operated a codeposition processing system that enables organic materials to be deposited on a variety of substrates to produce optical grade coatings and films. This system is also compatible with other traditional microelectronic techniques; (4) used the sol-gel process with colloidal AgTCNQ to fabricate high speed photochromic switches; (5) develop and applied for patent coverage to make VO2 optical switching materials via the sol-gel processing using vanadium (IV) alkoxide compounds.

  14. A comparative study of quantitative microsegregation analyses performed during the solidification of the Ni-base superalloy CMSX-10

    SciTech Connect

    Seo, Seong-Moon; Jeong, Hi-Won; Ahn, Young-Keun; Yun, Dae Won; Lee, Je-Hyun; Yoo, Young-Soo

    2014-03-01

    Quantitative microsegregation analyses were systematically carried out during the solidification of the Ni-base superalloy CMSX-10 to clarify the methodological effect on the quantification of microsegregation and to fully understand the solidification microstructure. Three experimental techniques, namely, mushy zone quenching (MZQ), planar directional solidification followed by quenching (PDSQ), and random sampling (RS), were implemented for the analysis of microsegregation tendency and the magnitude of solute elements by electron probe microanalysis. The microprobe data and the calculation results of the diffusion field ahead of the solid/liquid (S/L) interface of PDSQ samples revealed that the liquid composition at the S/L interface is significantly influenced by quenching. By applying the PDSQ technique, it was also found that the partition coefficients of all solute elements do not change appreciably during the solidification of primary γ. All three techniques could reasonably predict the segregation behavior of most solute elements. Nevertheless, the RS approach has a tendency to overestimate the magnitude of segregation for most solute elements when compared to the MZQ and PDSQ techniques. Moreover, the segregation direction of Cr and Mo predicted by the RS approach was found to be opposite from the results obtained by the MZQ and PDSQ techniques. This conflicting segregation behavior of Cr and Mo was discussed intensively. It was shown that the formation of Cr-rich areas near the γ/γ′ eutectic in various Ni-base superalloys, including the CMSX-10 alloy, could be successfully explained by the results of microprobe analysis performed on a sample quenched during the planar directional solidification of γ/γ′ eutectic. - Highlights: • Methodological effect on the quantification of microsegregation was clarified. • The liquid composition at the S/L interface was influenced by quenching. • The segregation direction of Cr varied depending on the

  15. Comparative thermal stability characteristics and isothermal oxidation behavior of an aluminized and a Pt-aluminized Ni-base superalloy

    SciTech Connect

    Tawancy, H.M.; Sridhar, N.; Abbas, N.M.; Rickerby, D.

    1995-11-01

    It is the objective of this paper to compare the thermal stability characteristics and isothermal oxidation behavior of an aluminide coating and a Pt-aluminide coating of the same Al content on a Ni-base superalloy. Addition of Pt to an aluminide coating was found to improve its thermal stability as well as its capability for selective oxidation of Al resulting in a purer scale of slower growth rate. This was correlated with the greater diffusional stability of the Pt-aluminide coating restricting the transport of substrate elements into the outer coating layers.

  16. Quantum transport behavior of Ni-based dinuclear complexes in presence of zigzag graphene nanoribbon as electrode

    NASA Astrophysics Data System (ADS)

    Sarkar, Sunandan; Pramanik, Anup; Sarkar, Pranab

    2016-10-01

    Quantum transport properties of some Ni-based dinuclear complexes with different polydentate organic ligands have been studied by applying abinitio density functional theory along with nonequilibrium Green's function formulations. It is demonstrated that these materials are capable of showing multifunctional spin dependent properties by the influence of edge states of zigzag edged graphene nanoribbons. The current-voltage characteristics of these materials show spin dependent negative differential resistance behavior, spin filtering effect, and also voltage rectifying property. Proper tuning of these materials can alter these effects which may be utilized in various spintronic devices.

  17. Observation of Localized Corrosion of Ni-Based Alloys Using Coupled Orientation Imaging Microscopy and Atomic Force Microscopy

    SciTech Connect

    Bedrossian, P.J.

    1999-11-24

    We present a method for assessing the relative vulnerabilities of distinct classes of grain boundaries to localized corrosion. Orientation imaging microscopy provides a spatial map which identifies and classifies grain boundaries at a metal surface. Once the microstructure of a region of a sample surface has been characterized, a sample can be exposed to repeated cycles of exposure to a corrosive environment alternating with topographic measurement by an atomic force microscope in the same region in which the microstructure had been mapped. When this procedure is applied to Ni and Ni-based alloys, we observe enhanced attack at random grain boundaries relative to special boundaries and twins in a variety of environments.

  18. The Mean vs Life-Limiting Fatigue Response of a Ni-Base Superalloy, Part 1: Mechanisms (Preprint)

    DTIC Science & Technology

    2008-09-01

    34’"L’\\" ~~·~~~:~~~?~i.. ~ ~I~~~.~.’ ,~.- .":_~ ••-:;’~.:-- 10JJITl 3 4 S 6 Grain diameter (",m) Figure 1: Microstructure of the INIOO...DATES COVERED (From - To) September 2008 Journal Article Preprint 4 . TITLE AND SUBTITLE THE MEAN VS LIFE-LIMITING FATIGUE RESPONSE OF A Ni-BASE...SUPERALLOY, PART 1: MECHANISMS (PREPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62102F 6 . AUTHOR(S

  19. Research into oil-based high-dispersion graphite lubricants for extrusion of Ni-based alloys

    NASA Astrophysics Data System (ADS)

    Petrov, Alexander N.; Petrov, Mikhail A.; Petrov, Pavel A.

    2016-10-01

    The presented paper deals with oil-based high-dispersion graphite lubricants for hot extrusion Ni-based alloys. This paper emphasize an influence of the lubricant's flash point and oil burning on composition changing of the lubricants. It was found out that oil-based lubricants increase heat shielding properties of the die during extrusion. The temperature of a die surface was estimated on the base of production tests on the mechanical press with nominal force of 1,6MN. The practical recommendations were presented and should help to choose lubricants properly in accordance to the analysis.

  20. Modular self-assembly, characterization, and host-guest chemistry of nanoscale organometallic architectures

    SciTech Connect

    Manna, J.; Kuehl, C.J.; Stang, P.J.; Muddiman, D.C.; Smith, R.D.

    1997-12-31

    The supramolecular synthesis and chemistry of organic macrocycles has been the focus of considerable study for over thirty years. In contrast, the chemistry of analogous inorganic and organometallic macrocycles is in it infancy; little is know about the stability, spectroscopic and physical properties, and chemistry of these species. We will report on the design of several unique supramolecular macrocycles and the characterization of these species by a range of spectroscopic techniques, including electrospray-ionization Fourier transform ion cyclotron resonance spectrometry. Preliminary data concerning the host-guest chemistry of these macrocycles will also be presented.

  1. 2001 Gordon Research Conference on Organometallic Chemistry. Final progress report [agenda and attendee list

    SciTech Connect

    Burns, Carol

    2001-07-27

    The Gordon Research Conference on Organometallic Chemistry was held at Salve Regina University, Newport, Rhode Island, July 22-27, 2001. The conference had 133 participants. The attendees represented the spectrum of endeavor in this field, coming from academia, industry, and government laboratories, and included US and foreign scientists, senior researchers, young investigators, and students. Emphasis was place on current unpublished research and discussion of the future target areas in this field. There was a conscious effort to stimulate lively discussion about the key issues in the field today. Time for formal presentations was limited in the interest of group discussions; poster sessions were held.

  2. Luminescent Cyclometalated Platinum Complexes with π-Bonded Catecholate Organometallic Ligands.

    PubMed

    Moussa, Jamal; Loch, Aruny; Chamoreau, Lise-Marie; Degli Esposti, Alessandra; Bandini, Elisa; Barbieri, Andrea; Amouri, Hani

    2017-02-20

    A series of cyclometalated platinum(II) complexes of the type [(ppy)Pt(LM)](n+) (n = 0, 1) with π-bonded catecholates acting as organometallic ligands (LM) have been prepared and characterized by analytical techniques. In addition, the structures of two complexes of the series were determined by single-crystal X-ray diffraction. The packing shows the formation of a 1D supramolecular assembly generated by dPt-πCp* interactions among individual units. All complexes are luminescent in the solid state and in solution media. The results of photophysics have been rationalized by means of density functional theory (DFT) and time-dependent DFT investigations.

  3. Exploration geochemical technique for the determination of preconcentrated organometallic halides by ICP-AES

    USGS Publications Warehouse

    Motooka, J.M.

    1988-01-01

    An atomic absorption extraction technique which is widely used in geochemical exploration for the determination of Ag, As, Au, Bi, Cd, Cu, Mo, Pb, Sb, and Zn has been modified and adapted to a simultaneous inductively coupled plasma-atomic emission instrument. the experimental and operating parameters are described for the preconcentration of the metals into their organometallic halides and for the determination of the metals. Lower limits of determination are equal to or improved over those for flame atomic absorption (except Au) and ICP results are very similar to the accepted AA values, with precision for the ICP data in excess of that necessary for exploration purposes.

  4. Combined quantum mechanical/molecular mechanics modeling for large organometallic and metallobiochemical systems

    NASA Astrophysics Data System (ADS)

    Leong, Max Kangchien

    A method of combined quantum mechanics/molecular mechanics has been developed to model larger organometallic and metallobiochemical systems where neither quantum mechanics nor molecular mechanics, applied separately, can solve the problem. An electronically transparent interface, which allows charge transfers between the quantum and classical fragments, is devised and realized by employing a special iterative procedure of double (intrafragment and interfragment) self-consistent calculations. The combined QM/MM scheme was successfully applied to model iron picket-fence porphyrin, vitamin B12, aquocobalamin, and vitamin B12 coenzyme molecules.

  5. Simulation and testing of a vertical organometallic vapor phase epitaxy reactor

    NASA Astrophysics Data System (ADS)

    Sani, R. A.; Barmawi, M.; Mindara, J. Y.

    1998-02-01

    The purpose of the study is to design a single wafer vertical organo-metallic vapor phase epitaxy (OMVPE) reactor which gives a uniform deposition around the symmetry axis. The vertical reactor under the consideration consist of a diffuser and a system of coaxial cylinders to laminarize the flow which may lead to a uniform deposition without rotating the susceptor. The simulation shows that for a susceptor with a radius of 2.5 cm, a uniformity can be achieved in a region of a radius of 2 cm within 1% for certain operating condition. The result is compared with the experimental measurement of TiO2 deposition from TTIP.

  6. Selective growth of GaAs by organometallic vapor phase epitaxy at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Azoulay, R.; Dugrand, L.

    1991-01-01

    Complete selective epitaxy of GaAs by organometallic vapor phase epitaxy at atmospheric pressure was achieved by using TMG, AsH3, and AsCl3 as starting gases. Selectivity was observed at growth temperatures ranging from 650 to 750 °C. The blocking of polycrystal deposition on the mask, Si3N4, or W, is attributed to the adsorption of HCl on the mask, thus preventing the nucleation of GaAs. On the openings, the growth rate may be adjusted by controlling the TMG/AsCl3 ratio. When TMG/AsCl3<1, no growth occurs, but etching is observed.

  7. Supported organometallic complexes, surface chemistry, spectroscopy, and catalysis. Progress report, September 15, 1992--November 14, 1993

    SciTech Connect

    Marks, T.J.

    1993-04-01

    Goal is to elucidate and understand the surface chemistry and catalytic properties of well-defined, highly-reactive organometallic molecules (principally based upon abundant actinide, lanthanide, and early transition elements) adsorbed on metal oxides and halides. Nature of adsorbed species is probed by a battery of chemical and physicochemical techniques, to understand the nature of the molecule-surface coordination chemistry and how this can give rise to extremely high catalytic activity. A complementary objective is to delineate the scope and mechanisms of the heterogeneous catalytic reactions, as well as to relate them both conceptually and functionally to model systems generated in solution.

  8. Investigation of fragmentation processes following core photoionization of organometallic molecules in the vapor phase

    NASA Astrophysics Data System (ADS)

    Nagaoka, Shin-ichi; Suzuki, Shinzo; Koyano, Inosuke

    1988-04-01

    Ionic fragmentation processes following ( n - 1)d core level photoionization of organometallic molecules have been studied in the vapor phase using synchrotron radiation. Results on tetramethyllead, tetramethyltin and tetramethylgermanium are reported. The threshold electron spectra and the photoionization efficiency curves of these molecules are presented and discussed. It is concluded that the ( n - 1)d 9 core-hole state of M(CH 3) 4 (M  Pb, Sn or Ge) is split into five sublevels owing to both the spin-orbi and the electrostatic perturbations by the methyl groups, and that the M + ions are predominantly produced following ( n - 1)d photoionization.

  9. (Comparison of group transfer, inner sphere and outer sphere electron transfer mechanisms of organometallic complexes: Progress report)

    SciTech Connect

    Atwood, J.

    1990-01-01

    We have constructed an infrared stopped-flow spectrophotometer and initiated a study of the mechanisms of reactions that involve a change in the oxidation state of organometallic complexes. In this summary we highlight our results on reactions (1) that formally involve exchange of a charged species between two metal carbonyl anions, (2) that involve addition of an electron to, or removal of an electron from organometallic complexes that contain a metal-metal bond, and (3) between coordination complexes and metal carbonyl anions.

  10. [Comparison of group transfer, inner sphere and outer sphere electron transfer mechanisms of organometallic complexes: Progress report

    SciTech Connect

    Atwood, J.

    1990-12-31

    We have constructed an infrared stopped-flow spectrophotometer and initiated a study of the mechanisms of reactions that involve a change in the oxidation state of organometallic complexes. In this summary we highlight our results on reactions (1) that formally involve exchange of a charged species between two metal carbonyl anions, (2) that involve addition of an electron to, or removal of an electron from organometallic complexes that contain a metal-metal bond, and (3) between coordination complexes and metal carbonyl anions.

  11. Organometallic synthesis, reactivity and catalysis in the solid state using well-defined single-site species

    PubMed Central

    Pike, Sebastian D.; Weller, Andrew S.

    2015-01-01

    Acting as a bridge between the heterogeneous and homogeneous realms, the use of discrete, well-defined, solid-state organometallic complexes for synthesis and catalysis is a remarkably undeveloped field. Here, we present a review of this topic, focusing on describing the key transformations that can be observed at a transition-metal centre, as well as the use of well-defined organometallic complexes in the solid state as catalysts. There is a particular focus upon gas–solid reactivity/catalysis and single-crystal-to-single-crystal transformations. PMID:25666064

  12. In vivo tumour and metastasis reduction and in vitro effects on invasion assays of the ruthenium RM175 and osmium AFAP51 organometallics in the mammary cancer model.

    PubMed

    Bergamo, A; Masi, A; Peacock, A F A; Habtemariam, A; Sadler, P J; Sava, G

    2010-01-01

    We have compared the organometallic arene complexes [(eta(6)-biphenyl)M(ethylenediamine)Cl](+) RM175 (M=Ru(II)) and its isostructural osmium(II) analogue AFAP51 (M=Os(II)) for their ability to induce cell detachment resistance from fibronectin, collagen IV and poly-l-lysine, and cell re-adhesion after treatment, their effects on cell migration and cell viability, on matrix metalloproteinases production, and on primary tumour growth of MCa mammary carcinoma, the effect of human serum albumin on their cytotoxicity. There are differences between ruthenium and osmium. The Os complex is up to 6x more potent than RM175 towards highly-invasive breast MDA-MB-231, human breast MCF-7 and human epithelial HBL-100 cancer cells, but whereas RM175 was active against MCa mammary carcinoma in vivo and caused metastasis reduction, AFAP51 was not. Intriguingly the presence of human serum albumin in the growth medium enhanced the cytotoxicity of both compounds. RM175 increased the resistance of MDA-MB-231 cells to detachment from substrates and both compounds inhibited the production of MMP-2. These data confirm the key role of ruthenium itself in anti-metastatic activity. It will be interesting to explore the activity of osmium arene complexes in other tumour models and the possibility of changing the non-arene ligands to tune the anticancer activity of osmium in vivo.

  13. Assessing the Effects of Radiation Damage on Ni-base Alloys for the Prometheus Space Reactor System

    SciTech Connect

    T. Angeliu

    2006-01-19

    Ni-base alloys were considered for the Prometheus space reactor pressure vessel with operational parameters of {approx}900 K for 15 years and fluences up to 160 x 10{sup 20} n/cm{sup 2} (E > 0.1 MeV). This paper reviews the effects of irradiation on the behavior of Ni-base alloys and shows that radiation-induced swelling and creep are minor considerations compared to significant embrittlement with neutron ,exposure. While the mechanism responsible for radiation-induced embrittlement is not fully understood, it is likely a combination of helium embrittlement and solute segregation that can be highly dependent on the alloy composition and exposure conditions. Transmutation calculations show that detrimental helium levels would be expected at the end of life for the inner safety rod vessel (thimble) and possibly the outer pressure vessel, primarily from high energy (E > 1 MeV) n,{alpha} reactions with {sup 58}Ni. Helium from {sup 10}B is significant only for the outer vessel due to the proximity of the outer vessel to the Be0 control elements. Recommendations for further assessments of the material behavior and methods to minimize the effects of radiation damage through alloy design are provided.

  14. Assessing the Effects of Radiation Damage on Ni-base Alloys for the Prometheus Space Reactor System

    SciTech Connect

    T Angeliu; J Ward; J Witter

    2006-04-04

    Ni-base alloys were considered for the Prometheus space reactor pressure vessel with operational parameters of {approx}900 K for 15 years and fluences up to 160 x 10{sup 20} n/cm{sup 2} (E > 0.1 MeV). This paper reviews the effects of irradiation on the behavior of Ni-base alloys and shows that radiation-induced swelling and creep are minor considerations compared to significant embrittlement with neutron exposure. While the mechanism responsible for radiation-induced embrittlement is not fully understood, it is likely a combination of helium embrittlement and solute segregation that can be highly dependent on the alloy composition and exposure conditions. Transmutation calculations show that detrimental helium levels would be expected at the end of life for the inner safety rod vessel (thimble) and possibly the outer pressure vessel, primarily from high energy (E > 1 MeV) n,{alpha} reactions with {sup 58}Ni. Helium from {sup 10}B is significant only for the outer vessel due to the proximity of the outer vessel to the BeO control elements. Recommendations for further assessments of the material behavior and methods to minimize the effects of radiation damage through alloy design are provided.

  15. Microstructure chemistry and mechanical properties of Ni-based superalloy Rene N4 under irradiation at room temperature

    DOE PAGES

    Sun, C.; Kirk, M.; Li, M.; ...

    2015-06-14

    Nickel superalloys with cubic L12 structured γ' (Ni3(Al, Ti)) precipitates exhibit high strength at high temperatures and excellent corrosion resistance when exposed to water. Unlike prior studies on irradiation damage of other Ni-based superalloys, our study on Rene N4 involves much larger γ' precipitates, ~450 nm in size, a size regime where the irradiation-induced disordering and dissolution kinetics and the corresponding mechanical property evolution are unknown. Under heavy ion irradiation at room temperature, the submicron-sized γ' precipitates were fully disordered at ~0.3 dpa and only later partially dissolved after 75 dpa irradiation. Nanoindentation experiments indicate that the mechanical properties ofmore » the alloy change significantly, with a dramatic decrease in hardness, with irradiation dose. Three contributions to the change in hardness were examined: defect clusters, disordering and dissolution. Moreover, the generation of defect clusters in the matrix and precipitates slightly increased the indentation hardness, while disordering of the submicron-sized γ' precipitates resulted in a dramatic decrease in the total hardness, which decreased further during the early stages of the intermixing between γ' precipitates and matrix (<18 dpa). As a result, controlling the long-range-ordering and chemical intermixing can be used to tailor the mechanical properties of Ni-based superalloys under irradiation.« less

  16. Microstructure chemistry and mechanical properties of Ni-based superalloy Rene N4 under irradiation at room temperature

    SciTech Connect

    Sun, C.; Kirk, M.; Li, M.; Hattar, Khalid Mikhiel; Wang, Y.; Anderoglu, O.; Valdez, J.; Uberuaga, B. P.; Dickerson, R.; Maloy, S. A.

    2015-06-14

    Nickel superalloys with cubic L12 structured γ' (Ni3(Al, Ti)) precipitates exhibit high strength at high temperatures and excellent corrosion resistance when exposed to water. Unlike prior studies on irradiation damage of other Ni-based superalloys, our study on Rene N4 involves much larger γ' precipitates, ~450 nm in size, a size regime where the irradiation-induced disordering and dissolution kinetics and the corresponding mechanical property evolution are unknown. Under heavy ion irradiation at room temperature, the submicron-sized γ' precipitates were fully disordered at ~0.3 dpa and only later partially dissolved after 75 dpa irradiation. Nanoindentation experiments indicate that the mechanical properties of the alloy change significantly, with a dramatic decrease in hardness, with irradiation dose. Three contributions to the change in hardness were examined: defect clusters, disordering and dissolution. Moreover, the generation of defect clusters in the matrix and precipitates slightly increased the indentation hardness, while disordering of the submicron-sized γ' precipitates resulted in a dramatic decrease in the total hardness, which decreased further during the early stages of the intermixing between γ' precipitates and matrix (<18 dpa). As a result, controlling the long-range-ordering and chemical intermixing can be used to tailor the mechanical properties of Ni-based superalloys under irradiation.

  17. Interplay between experiments and calculations for organometallic clusters and caged clusters

    SciTech Connect

    Nakajima, Atsushi

    2015-12-31

    Clusters consisting of 10-1000 atoms exhibit size-dependent electronic and geometric properties. In particular, composite clusters consisting of several elements and/or components provide a promising way for a bottom-up approach for designing functional advanced materials, because the functionality of the composite clusters can be optimized not only by the cluster size but also by their compositions. In the formation of composite clusters, their geometric symmetry and dimensionality are emphasized to control the physical and chemical properties, because selective and anisotropic enhancements for optical, chemical, and magnetic properties can be expected. Organometallic clusters and caged clusters are demonstrated as a representative example of designing the functionality of the composite clusters. Organometallic vanadium-benzene forms a one dimensional sandwich structure showing ferromagnetic behaviors and anomalously large HOMO-LUMO gap differences of two spin orbitals, which can be regarded as spin-filter components for cluster-based spintronic devices. Caged clusters of aluminum (Al) are well stabilized both geometrically and electronically at Al{sub 12}X, behaving as a “superatom”.

  18. Precursor nuclearity effects in supported vanadium oxides prepared by organometallic grafting.

    SciTech Connect

    Wegener, S. L.; Kim, H.; Marks, T. J.; Stair, P. C.

    2011-01-01

    Despite widespread importance in catalysis, the active and selective sites of supported vanadium oxide (VO{sub x}) catalysts are not well understood. Such catalysts are of great current interest because of their industrial significance and potential for selective oxidation processes. However, the fact that the nature of the active and selective sites is ambiguous hinders molecular level understanding of catalytic reactions and the development of new catalysts. Furthermore, complete structural elucidation requires isolation and characterization of specific vanadium oxide surface species, the preparation of which presents a significant synthetic challenge. In this study, we utilize the structural uniformity inherent in organometallic precursors for the preparation of supported vanadium oxide catalysts. The resulting catalysts are characterized by UV-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray absorption spectroscopy (XAS), UV-Raman spectroscopy, and H{sub 2}-temperature programmed reduction (H{sub 2}-TPR). Significant structural and reactivity differences are observed in catalysts prepared from different organometallic precursors, indicating that the chemical nature of surface vanadia can be influenced by the nuclearity of the precursor used for grafting.

  19. The optical characterization of organometallic complex thin films by spectroscopic ellipsometry and photovoltaic diode application

    SciTech Connect

    Özaydın, C.; Güllü, Ö.; Pakma, O.; Ilhan, S.; Akkılıç, K.

    2016-05-15

    Highlights: • Optical properties and thickness of the A novel organometallic complex (OMC) film were investigated by spectroscopic ellipsometry (SE). • Au/OMC/n-Si metal/interlayer/semiconductor (MIS) diode has been fabricated • This paper presents the I–V analysis of Au/OMC/n-Si MIS diode. • Current–voltage and photovoltaic properties of the diode were investigated. - Abstract: In this work, organometallic complex (OMC) films have been deposited onto glass or silicon substrates by spin coating technique and their photovoltaic application potential has been investigated. Optical properties and thickness of the film have been investigated by spectroscopic ellipsometry (SE). Also, transmittance spectrum has been taken by UV/vis spectrophotometer. The optical method has been used to determine the band gap value of the films. Also, Au/OMC/n-Si metal/interlayer/semiconductor (MIS) diode has been fabricated. Current–voltage and photovoltaic properties of the structure were investigated. The ideality factor (n) and barrier height (Φ{sub b}) values of the diode were found to be 2.89 and 0.79 eV, respectively. The device shows photovoltaic behavior with a maximum open-circuit voltage of 396 mV and a short circuit current of 33.8 μA under 300 W light.

  20. Transporting and shielding photosensitisers by using water-soluble organometallic cages: a new strategy in drug delivery and photodynamic therapy.

    PubMed

    Therrien, Bruno

    2013-06-24

    Skin photosensitivity remains one of the main limitations in photodynamic therapy. In this Concept article a strategy to overcome this limitation is described, in which the photosensitizer is hidden inside the hydrophobic cavity of a water-soluble organometallic cage. The metallacage not only protects the photosensitizer from light, it also facilitates its delivery to cancer cells.

  1. Reactivity of TEMPO toward 16- and 17-electron organometallic reaction intermediates: a time-resolved IR study.

    PubMed

    Lomont, Justin P; Nguyen, Son C; Harris, Charles B

    2013-07-31

    The (2,2,6,6-tetramethylpiperidin-1-yl)oxyl radical (TEMPO) has been employed for an extensive range of chemical applications, ranging from organometallic catalysis to serving as a structural probe in biological systems. As a ligand in an organometallic complex, TEMPO can exhibit several distinct coordination modes. Here we use ultrafast time-resolved infrared spectroscopy to study the reactivity of TEMPO toward coordinatively unsaturated 16- and 17-electron organometallic reaction intermediates. TEMPO coordinates to the metal centers of the 16-electron species CpCo(CO) and Fe(CO)4, and to the 17-electron species CpFe(CO)2 and Mn(CO)5, via an associative mechanism with concomitant oxidation of the metal center. In these adducts, TEMPO thus behaves as an anionic ligand, characterized by a pyramidal geometry about the nitrogen center. Density functional theory calculations are used to facilitate interpretation of the spectra and to further explore the structures of the TEMPO adducts. To our knowledge, this study represents the first direct characterization of the mechanism of the reaction of TEMPO with coordinatively unsaturated organometallic complexes, providing valuable insight into its reactions with commonly encountered reaction intermediates. The similar reactivity of TEMPO toward each of the species studied suggests that these results can be considered representative of TEMPO's reactivity toward all low-valent transition metal complexes.

  2. 10,000-Hour Cyclic Oxidation Behavior at 982 C (1800 F) of 68 High-Temperature Co-, Fe-, and Ni-Base Alloys

    NASA Technical Reports Server (NTRS)

    Barrett, Charles A.

    1997-01-01

    Sixty-eight high temperature Co-, Fe-, and Ni-base alloys were tested for 10-one thousand hour cycles in static air at 982 C (1800 F). The oxidation behavior of the test samples was evaluated by specific weight change/time data, x-ray diffraction of the post-test samples, and their final appearance. The gravimetric and appearance data were combined into a single modified oxidation parameter, KB4 to rank the cyclic oxidation resistance from excellent to catastrophic. The alloys showing the 'best' resistance with no significant oxidation attack were the alumina/aluminate spinel forming Ni-base turbine alloys: U-700, NASA-VIA and B-1900; the Fe-base ferritic alloys with Al: TRW-Valve, HOS-875, NASA-18T, Thermenol and 18SR; and the Ni-base superalloy IN-702.

  3. The effect of protective coatings on the high temperature properties of a gamma prime-strengthened Ni-base superalloy

    NASA Astrophysics Data System (ADS)

    Castillo, R.; Willett, K. P.

    1984-01-01

    The present study examined the influence of chrome-aluminide coatings on the creep and stress rupture properties of a wrought Udimet-520 nickel-base superalloy used in gas turbine blade applications. Creep and stress rupture tests were conducted at 802 °C (1475 °F) on coated and uncoated wrought bars in the fully heat treated condition. The tests showed that the application of the chrome-aluminide coatings caused a marked deterioration in rupture strength and ductility. Masking procedures used to protect the turbine blade roots during coating of the Ni-base superalloy also affected the rupture strength or rupture ductility. The mechanical behavior in the coated creep resistant alloy was correlated with the microstructure and is discussed in terms of possible controlling processes.

  4. Formation of Secondary Reaction Zones in Diffusion Aluminide-Coated Ni-Base Single-Crystal Superalloys Containing Ruthenium

    NASA Astrophysics Data System (ADS)

    Das, Dipak K.; Murphy, Kenneth S.; Ma, Shuwei; Pollock, Tresa M.

    2008-07-01

    The formation of secondary reaction zones (SRZs) beneath aluminide coatings in several Ru-bearing single-crystal Ni-base superalloys has been investigated. The presence of significant amounts of Ru in the superalloys did not prevent the formation of the secondary reaction zone. However, the Ru content of the alloys affected the type of refractory element-rich phase formed during the transformation. As the Ru content increased, the phase involved in the transformation shifted from the orthorhombic P to the β-RuAl phase. A differential tendency to SRZ formation was observed between the dendritic and interdendritic regions of the alloys. Significant growth of the SRZ was also observed during the high-temperature oxidation exposure of the coated alloys. The effects of the alloying elements on SRZ formation are discussed.

  5. The wetting characteristics and surface tension of some Ni-based alloys on yttria, hafnia, alumina, and zirconia substrates

    NASA Technical Reports Server (NTRS)

    Kanetkar, C. S.; Kacar, A. S.; Stefanescu, D. M.

    1988-01-01

    The surface tension and wetting characteristics of four commercial Ni-based alloys (UD718, Waspaloy, UD720, and UD520), pure Ni, and three special alloys (Ni-20 percent Cr, Ni-20 percent Cr-1 percent Al, and Ni-20 percent Cr-4 percent Al) on various ceramic substrates (including alumina, zirconia, hafnia, and yttria) were investigated using sessile drop experiments. Most of the systems studied exhibited a nonwetting behavior. Wetting improved with holding time at a given temperature to the point that some systems, such as Ni-20Cr on alumina, Ni-20Cr-4Al on alumina and on yttria, became marginally wetting. Wetting characteristics were apparently related to constitutional undercooling, which in turn could be affected by the metal dissolving some of the substrate during measurements.

  6. Corrosion behavior of Ni-base superalloys at 1373 K in simulated HTGR impure helium gas environment

    NASA Astrophysics Data System (ADS)

    Mutoh, Isao; Nakasone, Yuji; Hiraga, Keijiro; Tanabe, Tatsuhiko

    1993-12-01

    The present paper describes the corrosion behavior of recently developed Ni-base superalloys: an oxide dispersion strengthened (ODS) alloy, two kinds of Ni-Cr-W alloys and Hastelloy XR at 1373 K in a simulated HTGR impure helium gas. Corrosion tests were carried out using a transparent quartz retort at 1373 K for up to 3.6 Ms in circulating helium gas which contained a small amount of H 2, CH 4, CO, CO 2 and H 2O. The mass change versus exposure time relation revealed that the ODS alloy exhibited excellent oxidation resistance. One Ni-Cr-W alloy (113MA) and Hastelloy XR showed exfoliation of the oxide films after the tests. All the alloys were decarburized from the early exposure times. These results are discussed on the basis of phase stability diagrams for constituent elements in the alloys.

  7. Highly efficient growth of vertically aligned carbon nanotubes on Fe-Ni based metal alloy foils for supercapacitors

    NASA Astrophysics Data System (ADS)

    Amalina Raja Seman, Raja Noor; Asyadi Azam, Mohd; Ambri Mohamed, Mohd

    2016-12-01

    Supercapacitors are highly promising energy devices with superior charge storage performance and a long lifecycle. Construction of the supercapacitor cell, especially electrode fabrication, is critical to ensure good performance in applications. This work demonstrates direct growth of vertically aligned carbon nanotubes (CNTs) on Fe-Ni based metal alloy foils, namely SUS 310S, Inconel 600 and YEF 50, and their use in symmetric vertically aligned CNT supercapacitor electrodes. Alumina and cobalt thin film catalysts were deposited onto the foils, and then CNT growth was performed using alcohol catalytic chemical vapour deposition. By this method, vertically aligned CNTs were successfully grown and used directly as a binder-free supercapacitor electrode to deliver excellent electrochemical performance. The device showed relatively good specific capacitance, a superior rate capability and excellent cycle stability, maintaining about 96% capacitance up to 1000 cycles.

  8. V-Notched Bar Creep Life Prediction: GH3536 Ni-Based Superalloy Under Multiaxial Stress State

    NASA Astrophysics Data System (ADS)

    Zhang, D. X.; Wang, J. P.; Wen, Z. X.; Liu, D. S.; Yue, Z. F.

    2016-07-01

    In this study, creep experiments on smooth and circumferential V-type notched round bars were conducted in GH3536 Ni-based superalloy at 750 °C to identify notch strengthening effect in notched specimens. FE analysis was carried out, coupled with continuum damage mechanics (CDM), to analyze stress distribution and damage evolution under multiaxial stress state. The creep deformation of smooth specimens and the rupture life of both smooth and notched specimens showed good agreement between experimental results and FE analysis predictions; the creep rupture life for the notched specimen was successfully predicted via the "skeletal point" concept. Both creep damage analysis and the observed fracture morphology suggest that creep rupture started first at the root in the V-type notched specimens, and shifted to the region close to the notch root when the notch was relatively shallow compared to U-type notched specimens.

  9. Fabrication of High-Pressure Cold-Sprayed Coating on Ni-Based Superalloy for High-Temperature Corrosive Conditions

    NASA Astrophysics Data System (ADS)

    Singh, Harminder

    2015-11-01

    The surface behavior of the Ni-based superalloy (composition similar to UNS N06075) is altered in this study by depositing a 298- µm-thick coating for various erosive-corrosive and wear applications at a high temperature. The 50%Ni-50%Cr coating was developed by a high-pressure cold-spraying method. The coating microstructure was studied by various characterization techniques. The unmelted solid particles formed the coating structure, which is homogeneous, dense, hard, and free from cracks, oxides, and other defects. The coating composition and microstructure is suitable for providing protection to the substrate under high-temperature corrosive conditions. The developed coating performed well, with degradation rate of 0.47 mm/year, in the chlorine-based highly corrosive conditions of actual waste incinerator at 900°C.

  10. New Fe-Ni based metal-metalloid glassy alloys prepared by mechanical alloying and rapid solidification

    SciTech Connect

    Sunol, J.J.; Clavaguera-Mora, M.T.; Clavaguera, N.; Pradell, T.

    1997-12-31

    Mechanical alloying and rapid solidification are two important routes to obtain glassy alloys. New Fe-Ni based metal-metalloid (P-Si) alloys prepared by these two different processing routes were studied by differential scanning calorimetry and transmission Moessbauer spectroscopy. Mechanical alloyed samples were prepared with elemental precursors, and different nominal compositions. Rapidly solidified alloys were obtained by melt-spinning. The structural analyses show that, independent of the composition, the materials obtained by mechanical alloying are not completely disordered whereas fully amorphous alloys were obtained by rapid solidification. Consequently, the thermal stability of mechanically alloyed samples is lower than that of the analogous material prepared by rapid solidification. The P/Si ratio controls the magnetic interaction of the glassy ribbons obtained by rapid solidification. The experimental results are discussed in terms of the degree of amorphization and crystallization versus processing route and P/Si ratio content.

  11. Hardness and microstructural inhomogeneity at the epitaxial interface of laser 3D-printed Ni-based superalloy

    NASA Astrophysics Data System (ADS)

    Qian, Dan; Zhang, Anfeng; Zhu, Jianxue; Li, Yao; Zhu, Wenxin; Qi, Baolu; Tamura, Nobumichi; Li, Dichen; Song, Zhongxiao; Chen, Kai

    2016-09-01

    In this letter, microstructural and mechanical inhomogeneities, a great concern for single crystal Ni-based superalloys repaired by laser assisted 3D printing, have been probed near the epitaxial interface. Nanoindentation tests show the hardness to be uniformly lower in the bulk of the substrate and constantly higher in the epitaxial cladding layer. A gradient of hardness through the heat affected zone is also observed, resulting from an increase in dislocation density, as indicated by the broadening of the synchrotron X-ray Laue microdiffraction reflections. The hardening mechanism of the cladding region, on the other hand, is shown to originate not only from high dislocation density but also and more importantly from the fine γ/γ' microstructure.

  12. Effect of Co on Discontinuous Precipitation Transformation with TCP Phase in Ni-based Alloy Containing Re

    NASA Astrophysics Data System (ADS)

    Shi, Qianying; An, Ning; Huo, Jiajie; Zheng, Yunrong; Feng, Qiang

    2017-02-01

    The effect of Co on discontinuous precipitation (DP) transformation involving the formation of topologically close-packed (TCP) phase was investigated in three Ni-Cr-Re model alloys containing different levels of Co. One typical TCP phase, σ, was generated within DP cellular colonies along the migrating grain boundaries in experimental alloys during aging treatment. As a result of the increased solubility of Re in the γ matrix and enlarged interlamellar spacing of σ precipitates inside of growing DP colonies, Co addition suppressed the formation of σ phase and associated DP colonies. This study suggests that Co could potentially serve as a microstructural stabilizer in Re-containing Ni-base superalloys, which provides an alternative method for the composition optimization of superalloys.

  13. Application of Computational Thermodynamics to the Design of a Co-Ni-Based γ'-Strengthened Superalloy

    NASA Astrophysics Data System (ADS)

    Lass, Eric A.

    2017-03-01

    A currently available commercial Calphad thermodynamic database was utilized to investigate its applicability to alloy design in the new class of Co-Ni-based γ'-strengthened high-temperature alloys. A simple primary design criterion was chosen: maximize the γ' solvus temperature in the six-component Co-Ni-Al-Ti-W-Ta system while ensuring no formation of secondary, potentially deleterious phases. Secondary design considerations included the effects of alloying elements on equilibrium γ' volume fraction and on solidus and liquidus temperatures. The identified composition, Co-30Ni-9Al-3Ti-7W-2Ta-0.1B (expressed in mole percent), representing a conservative estimate of the maximum allowable concentrations of alloying additions Al, Ti, W, and Ta, was subsequently produced and characterized. The experimentally measured γ' solvus temperature of the new alloy was 1491 ± 3 K (1218 ± 3 °C), about 35 K (35 °C) above any previously reported two-phase γ-γ' Co-(Ni)-based alloy. No secondary phases were observed in the alloy after annealing at temperatures between 1173 K and 1473 K (900 °C and 1200 °C). Additional alloy compositions with experimentally measured γ' solvus temperatures in excess of 1533 K (1260 °C) were also identified employing the same basic approach. The efficacy of currently available thermodynamic databases in their application to Co-based γ'-strengthened superalloy development is discussed, including expanding design efforts to include additional alloying elements, as well as specific areas for improvement of future databases.

  14. Regeneration of Sulfur Deactivated Ni-based Biomass Syngas Cleaning Catalysts

    SciTech Connect

    Li, Liyu; Howard, Christopher J.; King, David L.; Gerber, Mark A.; Dagle, Robert A.; Stevens, Don J.

    2010-09-14

    Nickel-based catalysts have been widely tested in decomposing tar and methane in hot biomass syngas cleanup researches. However these catalysts can be easily deactivated by the sulfur compounds in syngas due to the strong sulfur adsorption effect on the Ni surface. Here we report on a new regeneration process, which can effectively and efficiently regenerate the sulfur-poisoned Ni reforming catalysts. This process consists of four sequential treatments: 1) controlled oxidation at 750oC in 1% O2, 2) decomposition at 900oC in Ar, 3) reduction at 900oC in 2% H2, and 4) reaction at 900oC under reforming condition. The duration of this 4-step regeneration process is only about 8 hours, which is shorter than that of the conventional steaming regeneration treatment.

  15. Stepwise formation of organometallic macrocycles and triangular prisms containing 2,2'-bisbenzimidazole ligands.

    PubMed

    Wu, Tong; Lin, Yue-Jian; Jin, Guo-Xin

    2013-01-07

    A series of organometallic macrocycles have been constructed by an efficient “bottom-up” assembly methodology at ambient temperature. Treatment of [Cp*MCl2]2 (1a: M = Ir, 1b: M = Rh) with pyrazine or 4,4′-bipyridine (bpy) (1:1; Cp* = pentamethylcyclopentadienyl) at room temperature resulted in the formation of binuclear complexes [Cp*MCl2]2(pyrazine) and [Cp*MCl2]2(bpy) (M = Ir or Rh), which were then further reacted with AgOTf (Tf = O2SCF3) and 2,2′-bisbenzimidazole ligand (BiBzIm). Four organometallic macrocyclic complexes formulated as [Cp*4Ir4(BiBzIm)2(pyrazine)2](OTf)4 (2a), [Cp*4Rh4(BiBzIm)2(pyrazine)2](OTf)4 (2b), [Cp*4Ir4(BiBzIm)2(bpy)2](OTf)4 (2c) and [Cp*4Rh4(BiBzIm)2(bpy)2](OTf)4 (2d) each bearing 2,2′-bisbenzimidazole ligand and the half-sandwich Ir, Rh fragments were finally obtained in good yields. In a similar process, if a rigid ligand L (3-pyridyl-bian) was used as the linker, two novel metallacycles (3a and 3b) which enchased a silver atom in the centre were obtained. Organometallic triangular prisms 4a were synthesized via methods similar to those of the rectangles. [Cp*IrCl2]2 reacted with tridentate ligand 2,4,6-tri(4-pyridyl)-1,3,5-triazine (tpt) to give the corresponding trinuclear complexes [Cp*IrCl2]3(tpt), then further reacted with AgOTf and 2,2′-bisbenzimidazole ligand, leading to the formation of the prism-like complexes formulated as [Cp*6M6(BiBzIm)6(tpt)2](OTf)6 (3a: M = Ir, 3b: M = Rh). All complexes were well characterized by 1H NMR and IR spectroscopy, as well as elemental analyses. The molecular structures of 2a, 2b, 2c, 3a, 3b and 4a were characterized by single-crystal X-ray crystallography. We found that the prism-like hexanuclear complexes 4a displayed interesting host–guest chemistry.

  16. Use of the Spin-Trapping method to establish the radical steps in the reactions of organic compounds of zinc, cadmium, and mercury with various peroxides

    SciTech Connect

    Dodonov, V.A.; Grishin, D.F.

    1985-06-01

    This paper uses the spin trapping method to investigate the homolytic reactions of group II organometallic compounds (OMC) with organic and heteroorganic peroxides. The radical reactions of the OMC with peroxides was investigated and the reactivity of the spin traps was examined with respect to compounds of zinc, cadmium, and mercury. Phenyl-tert-butylnitron (I), 2-methyl-2-nitrosopropane (II), and tri-bromonitrobenzene (III) were chosen as spin traps. The radicals formed are aable to initiate the polymerization of vinyl monomers.

  17. Ruthenium(II) and osmium(II) 1,2,3-triazolylidene organometallics: a preliminary investigation into the biological activity of 'click' carbene complexes.

    PubMed

    Kilpin, Kelly J; Crot, Stéphanie; Riedel, Tina; Kitchen, Jonathan A; Dyson, Paul J

    2014-01-21

    Taking advantage of the facile and versatile synthetic properties of 'click' 1,2,3-triazolylidene N-heterocyclic carbenes (tzNHC's), a range of new organometallic Ru(II) and Os(II) arene complexes containing functionalised tzNHC ligands, [M(η(6)-p-cymene)(tzNHC)Cl2] [M = Ru(II), Os(II)], have been synthesised and fully characterised, including the X-ray crystal structure of one of the Os(II) complexes. The tzNHC ligands remain coordinated to the metal centres under relevant physiological conditions, and following binding to the model protein, ubiquitin. The in vitro cytotoxicity of the compounds towards human ovarian cancer cells is dependent on the substituent on the tzNHC ligand but is generally <50 μM and in some cases <1 μM, whilst still retaining a high degree of selectivity towards cancer cells over healthy cells (1.85 μM in A2780 ovarian cancer cells versus 435 μM in human embryonic kidney cells in one case).

  18. Multi-targeted organometallic ruthenium(II)-arene anticancer complexes bearing inhibitors of poly(ADP-ribose) polymerase-1: A strategy to improve cytotoxicity.

    PubMed

    Wang, Zhigang; Qian, Hui; Yiu, Shek-Man; Sun, Jianwei; Zhu, Guangyu

    2014-02-01

    Small-molecule inhibitors of poly(ADP-ribose) polymerase-1 (PARP-1) have currently drawn much attention as promising chemotherapeutic drug candidates, and there is a need to develop more potent PARP inhibitors with improved bioavailability. Here we report a strategy to improve the cytotoxicity of PARP inhibitors by conjugation with organometallic ruthenium(II)-arene compounds. We also report a systematic study to reveal the mechanism of action of these ruthenium-PARP inhibitor conjugates. The complexes have been synthesized and characterized spectroscopically. The improved antiproliferative activity from the as-prepared complexes in four human cancer cell lines has indicated their potential for further development as antitumor drugs. Cellular uptake study reveals that the most active complex 3 easily entered into cells. Target validation assays show that the complexes inhibited PARP-1 slightly better than the original PARP inhibitors, that complex 3 strongly bound to DNA and inhibited transcription, and that this complex arrested the cell cycle at the G0/G1 stage. This type of information could shed light on the design of the next generation of more active ruthenium-PARP inhibitor conjugates.

  19. Organometallic model complexes elucidate the active gallium species in alkane dehydrogenation catalysts based on ligand effects in Ga K-edge XANES

    SciTech Connect

    Getsoian, Andrew “Bean”; Das, Ujjal; Camacho-Bunquin, Jeffrey; Zhang, Guanghui; Gallagher, James R.; Hu, Bo; Cheah, Singfoong; Schaidle, Joshua A.; Ruddy, Daniel A.; Hensley, Jesse E.; Krause, Theodore R.; Curtiss, Larry A.; Miller, Jeffrey T.; Hock, Adam S.

    2016-01-01

    Gallium-modified zeolites are known catalysts for the dehydrogenation of alkanes, reactivity that finds industrial application in the aromatization of light alkanes by Ga-ZSM5. While the role of gallium cations in alkane activation is well known, the oxidation state and coordination environment of gallium under reaction conditions has been the subject of debate. Edge shifts in Ga K-edge XANES spectra acquired under reaction conditions have long been interpreted as evidence for reduction of Ga(III) to Ga(I). However, a change in oxidation state is not the only factor that can give rise to a change in the XANES spectrum. In order to better understand the XANES spectra of working catalysts, we have synthesized a series of molecular model compounds and grafted surface organometallic Ga species and compared their XANES spectra to those of gallium-based catalysts acquired under reducing conditions. We demonstrate that changes in the identity and number of gallium nearest neighbors can give rise to changes in XANES spectra similar to those attributed in literature to changes in oxidation state. Specifically, spectral features previously attributed to Ga(I) may be equally well interpreted as evidence for low-coordinate Ga(III) alkyl or hydride species. These findings apply both to gallium-impregnated zeolite catalysts and to silica-supported single site gallium catalysts, the latter of which is found to be active and selective for dehydrogenation of propane and hydrogenation of propylene.

  20. Toward new organometallic architectures: synthesis of carbene-centered rhodium and palladium bisphosphine complexes. stability and reactivity of [PC(BIm)PRh(L)][PF6] pincers.

    PubMed

    Plikhta, Andriy; Pöthig, Alexander; Herdtweck, Eberhardt; Rieger, Bernhard

    2015-10-05

    In this article, we report the synthesis of a tridentate carbene-centered bisphosphine ligand precursor and its complexes. The developed four-step synthetic strategy of a new PC(BIm)P pincer ligand represents the derivatization of benzimidazole in the first and third positions by (diphenylphosphoryl)methylene synthone, followed by phosphine deprotection and subsequent insertion of a noncoordinating anion. The obtained ligand precursor undergoes complexation, with PdCl2 and [μ-OCH3Rh(COD)]2 smoothly forming the target organometallics [PC(BIm)PPdCl][PF6] and [PC(BIm)PRh(L)][PF6] under mild hydrogenation conditions. A more detailed study of the rhodium complexes [PC(BIm)PRh(L)][PF6] reveals significant thermal stability of the PC(BIm)PRh moiety in the solid state as well as in solution. The chemical behavior of 1,3-bis(diphenylphosphinomethylene)benzimidazol-2-ylrhodium acetonitrile hexafluorophosphate has been screened under decarbonylation, hydrogenation, and hydroboration reaction conditions. Thus, the PC(BIm)PRh(I) complex is a sufficiently stable compound, with the potential to be applied in catalysis.

  1. Technomimetic molecules: synthesis of ruthenium(II) 1,2,3,4,5-penta(p-bromophenyl)cyclopentadienyl hydrotris(indazolyl)borate, an organometallic molecular turnstile.

    PubMed

    Carella, Alexandre; Jaud, Jöel; Rapenne, Gwénaël; Launay, Jean-Pierre

    2003-10-07

    A short route to prepare a ruthenium complex with a pentaphenyl substituted cyclopentadienyl and a hydrotris(indazolyl)borate ligand is described: this complex can be seen as an organometallic molecular turnstile.

  2. Microelectrode fabrication by laser direct curing of tiny nanoparticle self-generated from organometallic ink.

    PubMed

    Kang, Bongchul; Ko, Seunghwan; Kim, Jongsu; Yang, Minyang

    2011-01-31

    In this paper, we present a new laser direct patterning method that selectively cures nanoparticles self-generated from organometallic ink by proper thermal decomposition. This approach has several advantages in the curing rate, resolution and pattern quality compared with the conventional nanoparticle ink based direct laser curing method. It was found that a laser wavelength which is more weakly absorbed by the nanoparticles could produce a more stable and homogeneous curing condition. Finally, arbitrary shaped silver electrodes with narrow width and uniform profile could be achieved on a polymer substrate at a high curing rate of 25 mm/s. This process can be applied for flexible electronics fabrications on heat sensitive polymer substrates.

  3. Low oxygen and carbon incorporation in AIGaAs using tritertiarybutylaluminum in organometallic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Wang, C. A.; Salimand, S.; Jensen, K. F.; Jones, A. C.

    1996-05-01

    High-quality AIGaAs epilayers have been grown by low pressure organometallic vapor phase epitaxy with a new aluminum precursor tritertiarybutylaluminum (TTBAl). Layers grown at 650°C have a featureless mirror surface morphology and strong room temperature photoluminescence. Carbon was not detectable in chemical analysis by secondary ion mass spectroscopy, nor in low temperature (4K) photoluminescence spectra. Oxygen concentration in Al0.25Ga0.75As is as low as ˜2-3 × 1017 cm-3. Nominally undoped AIGaAs layers exhibit n-type conductiv-ity with electron concentrations at ˜ 1-1.5 × 1016 cm-3. A high degree of compo-sitional uniformity over 5 cm diam substrates (0.268 ±0.001) was obtained. These results indicate the potential for TTBA1 as an aluminum precursor for low temperature growth of Al-containing III-V alloys.

  4. Reactivity of seventeen- and nineteen-valence electron complexes in organometallic chemistry

    NASA Technical Reports Server (NTRS)

    Stiegman, Albert E.; Tyler, David R.

    1986-01-01

    A guideline to the reactivity of 17- and 19-valence electron species in organometallic chemistry is proposed which the authors believe will supersede all others. The thesis holds that the reactions of 17-electron metal radicals are associatively activated with reactions proceeding through a 19-valence electron species. The disparate reaction chemistry of the 17-electron metal radicals are unified in terms of this associative reaction pathway, and the intermediacy of 19-valence electron complexes in producing the observed products is discussed. It is suggested that related associatively activated pathways need to be considered in some reactions that are thought to occur by more conventional routes involving 16- and 18-electron intermediates. The basic reaction chemistry and electronic structures of these species are briefly discussed.

  5. Metal-organometallic polymers and frameworks derived from facially metalated arylcarboxylates

    NASA Astrophysics Data System (ADS)

    Kumalah Robinson, Sayon A.

    The interest in coordination polymers, also known as metal-organic frameworks, has risen drastically over the past 2 decades. In this time, the field has matured and given rise to a diverse range of crystalline structures possessing various functionalities. Coordination polymers are typically formed from the self assembly of metal ions which serve as nodes and organic ligands which act as bridges. By the careful selection of the organic ligand and the metal ion, the overall physical properties of the material may be tuned. In this work, the use of organometallic bridging ligands are explored using facially metalated aryl carboxylates ligands to synthesize metal-organometallic frameworks (MOMFs). Therefore, with the aim of synthesizing [CpM]+-functionalized (M = FeII, RuII; Cp = cyclopentadienyl) coordination polymers and metal organic frameworks, various [CpFe]+and [CpRu] + functionalized aryl carboxylates were synthesized and characterized. In particular, the [CpFe]+-functionalized benzoic, terephthalic and trimesic acids as well as the [CpRu]+-functionalized terephthalic acid were made. Using the [CpFe]+ complexes of the benzoic and terephthalic acid as bridging ligands, a number of 1D and 2D coordination polymers were synthesized. For instance, the reaction of [CpFe]+-functionalized benzoic acid with CdCl2 yielded the 1D chain of [Cd(benzoate)Cl 2]˙H2O whilst the reaction of [CpFe]+-functionalized terephthalic acid with Cu(NO3)2˙6H2O yielded a 2D square grid sheet. Using the [CpFe]+-functionalized terephthalic acid, a series of polymorphic, 3D metal-organometallic frameworks of the general formula [M3(terephthalate)4(mu-H2O)2(H 2O)2][NO3]2˙xsolvent (M = Co II, NiII ; solvent = EtOH, DMF, H2O) were synthesized and fully characterized. The polymorphic nature of these frameworks may be attributed to the different orientations that the [CpFe]+ moiety may adapt within the cavities in the 3D frameworks. The selectivity of the desolvated forms of the polymorphs for

  6. Quasi-one-dimensional spin-orbit-coupled correlated insulator in a multinuclear coordinated organometallic crystal

    NASA Astrophysics Data System (ADS)

    Merino, J.; Jacko, A. C.; Khosla, A. L.; Powell, B. J.

    2016-11-01

    We show how quasi-one-dimensional correlated insulating states arise at two-thirds filling in organometallic multinuclear coordination complexes described by layered decorated honeycomb lattices. The interplay of spin-orbit coupling and electronic correlations leads to pseudospin-one moments arranged in weakly coupled chains with highly anisotropic exchange and a large trigonal splitting. We show that the in-plane exchange coupling is very different from the interlayer coupling; in particular the latter is much larger, despite the underlying hopping integrals being close to isotropic. Surprisingly, the effective dimensionality of the pseudospin model is strongly dependent on the strength of the electronic correlations: With increasing Hubbard U the pseudospin-one model becomes increasingly one dimensional, even though the crystal is almost isotropic. We predict that the trigonal splitting leads to a quantum phase transition from a Haldane phase to a topologically trivial phase as the relative strength of the spin-orbit coupling increases.

  7. p-type Mesoscopic nickel oxide/organometallic perovskite heterojunction solar cells.

    PubMed

    Wang, Kuo-Chin; Jeng, Jun-Yuan; Shen, Po-Shen; Chang, Yu-Cheng; Diau, Eric Wei-Guang; Tsai, Cheng-Hung; Chao, Tzu-Yang; Hsu, Hsu-Cheng; Lin, Pei-Ying; Chen, Peter; Guo, Tzung-Fang; Wen, Ten-Chin

    2014-04-23

    In this article, we present a new paradigm for organometallic hybrid perovskite solar cell using NiO inorganic metal oxide nanocrystalline as p-type electrode material and realized the first mesoscopic NiO/perovskite/[6,6]-phenyl C61-butyric acid methyl ester (PC61BM) heterojunction photovoltaic device. The photo-induced transient absorption spectroscopy results verified that the architecture is an effective p-type sensitized junction, which is the first inorganic p-type, metal oxide contact material for perovskite-based solar cell. Power conversion efficiency of 9.51% was achieved under AM 1.5 G illumination, which significantly surpassed the reported conventional p-type dye-sensitized solar cells. The replacement of the organic hole transport materials by a p-type metal oxide has the advantages to provide robust device architecture for further development of all-inorganic perovskite-based thin-film solar cells and tandem photovoltaics.

  8. Anodic Deposition of a Robust Iridium-Based Water-Oxidation Catalyst from Organometallic Precursors

    SciTech Connect

    Blakemore, James D; Schley, Nathan D; Olack, G.; Incarvito, Christopher D; Brudvig, Gary W; Crabtree, Robert H

    2011-01-01

    Artificial photosynthesis, modeled on natural light-driven oxidation of water in Photosystem II, holds promise as a sustainable source of reducing equivalents for producing fuels. Few robust water-oxidation catalysts capable of mediating this difficult four-electron, four-proton reaction have yet been described. We report a new method for generating an amorphous electrodeposited material, principally consisting of iridium and oxygen, which is a robust and long-lived catalyst for water oxidation, when driven electrochemically. The catalyst material is generated by a simple anodic deposition from Cp*Ir aqua or hydroxo complexes in aqueous solution. This work suggests that organometallic precursors may be useful in electrodeposition of inorganic heterogeneous catalysts.

  9. A Photoferroelectric Perovskite-Type Organometallic Halide with Exceptional Anisotropy of Bulk Photovoltaic Effects.

    PubMed

    Sun, Zhihua; Liu, Xitao; Khan, Tariq; Ji, Chengmin; Asghar, Muhammad Adnan; Zhao, Sangen; Li, Lina; Hong, Maochun; Luo, Junhua

    2016-05-23

    Perovskite-type ferroelectrics composed of organometallic halides are emerging as a promising alternative to conventional photovoltaic devices because of their unique photovoltaic effects (PVEs). A new layered perovskite-type photoferroelectric, bis(cyclohexylaminium) tetrabromo lead (1), is presented. The material exhibits an exceptional anisotropy of bulk PVEs. Upon photoexcitation, superior photovoltaic behaviors are created along its inorganic layers, which are composed of corner-sharing PbBr6 octahedra. Semiconducting activity with remarkable photoconductivity is achieved in the vertical direction, showing sizeable on/off current ratios (>10(4) ), which compete with the most active photovoltaic material CH3 NH3 PbI3 . In 1 the temperature-dependence of photovoltage coincides fairly well with that of polarization, confirming the dominant role of ferroelectricity in such highly anisotropic PVEs. This finding sheds light on bulk PVEs in ferroelectric materials, and promotes their application in optoelectronic devices.

  10. Radical SAM catalysis via an organometallic intermediate with an Fe-[5'-C]-deoxyadenosyl bond.

    PubMed

    Horitani, Masaki; Shisler, Krista; Broderick, William E; Hutcheson, Rachel U; Duschene, Kaitlin S; Marts, Amy R; Hoffman, Brian M; Broderick, Joan B

    2016-05-13

    Radical S-adenosylmethionine (SAM) enzymes use a [4Fe-4S] cluster to cleave SAM to initiate diverse radical reactions. These reactions are thought to involve the 5'-deoxyadenosyl radical intermediate, which has not yet been detected. We used rapid freeze-quenching to trap a catalytically competent intermediate in the reaction catalyzed by the radical SAM enzyme pyruvate formate-lyase activating enzyme. Characterization of the intermediate by electron paramagnetic resonance and (13)C, (57)Fe electron nuclear double-resonance spectroscopies reveals that it contains an organometallic center in which the 5' carbon of a SAM-derived deoxyadenosyl moiety forms a bond with the unique iron site of the [4Fe-4S] cluster. Discovery of this intermediate extends the list of enzymatic bioorganometallic centers to the radical SAM enzymes, the largest enzyme superfamily known, and reveals intriguing parallels to B12 radical enzymes.

  11. Design, synthesis, and carbon-heteroatom coupling reactions of organometallic nickel(IV) complexes.

    PubMed

    Camasso, Nicole M; Sanford, Melanie S

    2015-03-13

    Homogeneous nickel catalysis is used for the synthesis of pharmaceuticals, natural products, and polymers. These reactions generally proceed via nickel intermediates in the Ni(0), Ni(I), Ni(II), and/or Ni(III) oxidation states. In contrast, Ni(IV) intermediates are rarely accessible. We report herein the design, synthesis, and characterization of a series of organometallic Ni(IV) complexes, accessed by the reaction of Ni(II) precursors with the widely used oxidant S-(trifluoromethyl)dibenzothiophenium triflate. These Ni(IV) complexes undergo highly selective carbon(sp(3))-oxygen, carbon(sp(3))-nitrogen, and carbon(sp(3))-sulfur coupling reactions with exogenous nucleophiles. The observed reactivity has the potential for direct applications in the development of nickel-catalyzed carbon-heteroatom coupling reactions.

  12. Preparation and characterization of barium hexaferrite powders produced by decomposition of organometallic complexes

    SciTech Connect

    Chandrasekhar, R.; Charles, S.W.; O'Grady, K. ); Moerup, S.; van Wonterghem, J. )

    1987-01-01

    Barium hexaferrite (BaFe{sub 12}O{sub 19}) particles have been prepared by the decomposition of an organometallic salt. The properties of the ferrite particles have been investigated by x-ray diffractometry, Moessbauer spectroscopy, scanning electron microscopy, and magnetic measurements. The size of the particles produced lie between 0.1 and 0.5 {mu}m. To form the hexaferrite the decomposition product must be heated to > 620{degree}C. Typical values of the saturation magnetization, coercivity, and remanence ratio of the hexaferrite particles are 333 kA{center dot}m{sup {minus}1} (63 emu/g{sup {minus}1}), 320 kA{center dot}m{sup {minus}1} (4 kOe), and 0.49, respectively.

  13. Organometallic Polymers.

    ERIC Educational Resources Information Center

    Carraher, Charles E., Jr.

    1981-01-01

    Reactions utilized to incorporate a metal-containing moiety into a polymer chain (addition, condensation, and coordination) are considered, emphasizing that these reactions also apply to smaller molecules. (JN)

  14. Recent progress in GaInAsSb thermophotovoltaics grown by organometallic vapor phase epitaxy

    SciTech Connect

    Wang, C.A.; Choi, H.K.; Oakley, D.C.; Charache, G.W.

    1998-06-01

    Studies on the materials development of Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} alloys for thermophotovoltaic (TPV) devices are reviewed. Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} epilayers were grown lattice matched to GaSb substrates by organometallic vapor phase epitaxy (OMVPE) using all organometallic precursors including triethylgallium, trimethylindium, tertiarybutylarsine, and trimethylantimony with diethyltellurium and dimethylzinc as the n- and p-type dopants, respectively. The overall material quality of these alloys depends on growth temperature, In content, V/III ratio, substrate misorientation, and to a lesser extent, growth rate. A mirror-like surface morphology and room temperature photoluminescence (PL) are obtained for GaInAsSb layers with peak emission in the wavelength range between 2 and 2.5 {micro}m. The crystal quality improves for growth temperature decreasing from 575 to 525 C, and with decreasing In content, as based on epilayer surface morphology and low temperature PL spectra. A trend of smaller full width at half-maximum for low temperature PL spectra is observed as the growth rate is increased from 1.5 to 2.5 and 5 {micro}m/h. In general, GaInAsSb layers grown on (100) GaSb substrates with a 6{degree} toward (111)B misorientation exhibited overall better material quality than layers grown on the more standard substrate (100)2{degree} toward (110). Consistent growth of high performance lattice-matched GaInAsSb TPV devices is also demonstrated.

  15. NMR studies in chemistry. I. Organometallic tin and geramanium compounds. II. The sorbitol pathway in intact lenses

    SciTech Connect

    Williams, W.F.

    1985-01-01

    Nuclear magnetic resonance spectroscopy has been utilized in the study of two very different chemical problems. The bonding and structure of various cyclopropyl derivatives of tin and germanium has been investigated by means of Sn-119, Ge-73, C-13, and H-1 NMR spectroscopy. Intact rabbit lenses have also been studied using NMR spectroscopy with regard to diabetic cataract formation. C-13 and P-31 NMR spectroscopies have been utilized in the study of the sorbitol pathway and aldose reductase inhibition.

  16. Photonics of a conjugated organometallic Pt-Ir polymer and its model compounds exhibiting hybrid CT excited states.

    PubMed

    Soliman, Ahmed M; Fortin, Daniel; Zysman-Colman, Eli; Harvey, Pierre D

    2012-04-13

    Trans- dichlorobis(tri-n-butylphosphine)platinum(II) reacts with bis(2- phenylpyridinato)-(5,5'-diethynyl-2,2'-bipyridine)iridium(III) hexafluorophosphate to form the luminescent conjugated polymer poly[trans-[(5,5'-ethynyl-2,2'-bipyridine)bis(2- phenylpyridinato)-iridium(III)]bis(tri-n-butylphosphine)platinum(II)] hexafluorophosphate ([Pt]-[Ir])n. Gel permeation chromatography indicates a degree of polymerization of 9 inferring the presence of an oligomer. Comparison of the absorption and emission band positions and their temperature dependence, emission quantum yields, and lifetimes with those for models containing only the [Pt] or the [Ir] units indicates hybrid excited states including features from both chromophores.

  17. Studies on the reactivity of organometallic Ru-, Rh- and Os-pta complexes with DNA model compounds.

    PubMed

    Dorcier, Antoine; Hartinger, Christian G; Scopelliti, Rosario; Fish, Richard H; Keppler, Bernhard K; Dyson, Paul J

    2008-01-01

    The reactions of arene-metal complexes (arene=p-cymene, benzene or pentamethylcyclopentadienyl, metal=Ru, Rh or Os), including 1,3,5-triaza-7-phosphatricyclo-[3.3.1.1]decanephosphine (pta) and chloro co-ligands, with 9-methylguanine, adenine, and a series of nucleosides were studied in water to ascertain the binding modes. The products were characterized by NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS). Tandem mass spectrometry was found to provide excellent information on preferential binding sites. In general, the N7 position on guanine (the most basic site) was found to be the preferred donor atom for coordination to the metal complexes. The X-ray structures of the precursor complexes, [(eta5-C10H15)RhCl(pta-Me)2]Cl2, [(eta6-C10H14)OsCl(pta)2]Cl, and [(eta6-C6H6)OsCl2(CH3CN)], are also reported.

  18. Crystal and molecular structures of selected organic and organometallic compounds and an algorithm for empirical absorption correction

    SciTech Connect

    Karcher, B.

    1981-10-01

    Cr(CO)/sub 5/(SCMe/sub 2/) crystallizes in the monoclinic space group P2/sub 1//a with a = 10.468(8), b = 11.879(5), c = 9.575(6) A, and ..beta.. = 108.14(9)/sup 0/, with an octahedral coordination around the chromium atom. PSN/sub 3/C/sub 6/H/sub 12/ crystallizes in the monoclinic space group P2/sub 1//n with a = 10.896(1), b = 11.443(1), c = 7.288(1) A, and ..beta.. = 104.45(1)/sup 0/. Each of the five-membered rings in this structure contains a carbon atom which is puckered toward the sulfur and out of the nearly planar arrays of the remaining ring atoms. (RhO/sub 4/N/sub 4/C/sub 48/H/sub 56/)/sup +/(BC/sub 24/H/sub 20/)/sup -/.1.5NC/sub 2/H/sub 3/ crystallizes in the triclinic space group P1 with a = 17.355(8), b = 21.135(10), c = 10.757(5) A, ..cap alpha.. = 101.29(5), ..beta.. = 98.36(5), and ..gamma.. = 113.92(4)/sup 0/. Each Rh cation complex is a monomer. MoP/sub 2/O/sub 10/C/sub 16/H/sub 22/ crystallizes in the monoclinic space group P2/sub 1//c with a = 12.220(3), b = 9.963(2), c = 20.150(6) A, and ..beta.. = 103.01(3)/sup 0/. The molybdenum atom occupies the axial position of the six-membered ring of each of the two phosphorinane ligands. An empirical absorption correction program was written.

  19. Electron-Transfer Reactions of Organometallic and Coordination Compounds in the Absence of Solvent: Experimental Results and Theoretical Approaches

    DTIC Science & Technology

    1988-07-07

    OI C FILE COF AD-A 197 086 ). ... ENTA TION PAGE AD A 197 086 b. RESTRICTIVE MARKINGS L~ a. SECURITY CLASSIFICATION AUTH 3. DISTRIBUTION/ AV...and theoretically estimated factors are compared to experiment for a typical metallocene, ferrocene . (’ 20. DISTRIBUItuN/AVAILABILITY OF ABSTRACT 21...is examined, and theoretically estimated factors are ,’or compared to experiment for a typical metallocene, ferrocene . I L) I t *~6% ~ * ’." .-- 4

  20. Unravelling novel synergies between organometallic and biological partners: a quantum mechanics/molecular mechanics study of an artificial metalloenzyme

    PubMed Central

    Ortega-Carrasco, Elisabeth; Lledós, Agustí; Maréchal, Jean-Didier

    2014-01-01

    In recent years, the design of artificial metalloenzymes obtained by the insertion of homogeneous catalysts into biological macromolecules has become a major field of research. These hybrids, and the corresponding X-ray structures of several of them, are offering opportunities to better understand the synergy between organometallic and biological subsystems. In this work, we investigate the resting state and activation process of a hybrid inspired by an oxidative haemoenzyme but presenting an unexpected reactivity and structural features. An extensive series of quantum mechanics/molecular mechanics calculations show that the resting state and the activation processes of the novel enzyme differ from naturally occurring haemoenzymes in terms of the electronic state of the metal, participation of the first coordination sphere of the metal and the dynamic process. This study presents novel insights into the sensitivity of the association between organometallic and biological partners and illustrates the molecular challenge that represents the design of efficient enzymes based on this strategy. PMID:24829279

  1. Unravelling novel synergies between organometallic and biological partners: a quantum mechanics/molecular mechanics study of an artificial metalloenzyme.

    PubMed

    Ortega-Carrasco, Elisabeth; Lledós, Agustí; Maréchal, Jean-Didier

    2014-07-06

    In recent years, the design of artificial metalloenzymes obtained by the insertion of homogeneous catalysts into biological macromolecules has become a major field of research. These hybrids, and the corresponding X-ray structures of several of them, are offering opportunities to better understand the synergy between organometallic and biological subsystems. In this work, we investigate the resting state and activation process of a hybrid inspired by an oxidative haemoenzyme but presenting an unexpected reactivity and structural features. An extensive series of quantum mechanics/molecular mechanics calculations show that the resting state and the activation processes of the novel enzyme differ from naturally occurring haemoenzymes in terms of the electronic state of the metal, participation of the first coordination sphere of the metal and the dynamic process. This study presents novel insights into the sensitivity of the association between organometallic and biological partners and illustrates the molecular challenge that represents the design of efficient enzymes based on this strategy.

  2. Functionalization of a ruthenium-diacetylide organometallic complex as a next-generation push-pull chromophore.

    PubMed

    De Sousa, Samuel; Ducasse, Laurent; Kauffmann, Brice; Toupance, Thierry; Olivier, Céline

    2014-06-02

    The design and preparation of an asymmetric ruthenium-diacetylide organometallic complex was successfully achieved to provide an original donor-π-[M]-π-acceptor architecture, in which [M] corresponds to the [Ru(dppe)2] (dppe: bisdiphenylphosphinoethane) metal fragment. The charge-transfer processes occurring upon photoexcitation of the push-pull metal-dialkynyl σ complex were investigated by combining experimental and theoretical data. The novel push-pull complex, appropriately end capped with an anchoring carboxylic acid function, was further adsorbed onto a semiconducting metal oxide porous thin film to serve as a photosensitizer in hybrid solar cells. The resulting photoactive material, when embedded in dye-sensitized solar cell devices, showed a good spectral response with a broad incident photon-to-current conversion efficiency profile and a power conversion efficiency that reached 7.3 %. Thus, this material paves the way to a new generation of organometallic chromophores for photovoltaic applications.

  3. Organometallic nickel(III) complexes relevant to cross-coupling and carbon-heteroatom bond formation reactions.

    PubMed

    Zheng, Bo; Tang, Fengzhi; Luo, Jia; Schultz, Jason W; Rath, Nigam P; Mirica, Liviu M

    2014-04-30

    Nickel complexes have been widely employed as catalysts in C-C and C-heteroatom bond formation reactions. In addition to Ni(0) and Ni(II) intermediates, several Ni-catalyzed reactions are proposed to also involve odd-electron Ni(I) and Ni(III) oxidation states. We report herein the isolation, structural and spectroscopic characterization, and organometallic reactivity of Ni(III) complexes containing aryl and alkyl ligands. These Ni(III) species undergo transmetalation and/or reductive elimination reactions to form new C-C or C-heteroatom bonds and are also competent catalysts for Kumada and Negishi cross-coupling reactions. Overall, these results provide strong evidence for the direct involvement of organometallic Ni(III) species in cross-coupling reactions and oxidatively induced C-heteroatom bond formation reactions.

  4. Search for the ground-state electronic configurations of correlated organometallic metallocenes from constraint density functional theory

    NASA Astrophysics Data System (ADS)

    Nawa, Kenji; Kitaoka, Yukie; Nakamura, Kohji; Imamura, Hiroshi; Akiyama, Toru; Ito, Tomonori; Weinert, M.

    2016-07-01

    The ground-state electronic configurations of the correlated organometallic metallocenes, M Cp2,M =V , Cr, Mn, Fe, Co, and Ni, are investigated using constraint density functional theory combined with nonempirical Ueff parameters determined from linear-response theory. The relative stability of the various d -orbital electronic configurations of these organometallic molecules is found to be sensitive to the amount of correlation. Using nonempirical values of Ueff, the calculated electronic configurations are in agreement with the experiments: 4A2 g ,3E2 g ,6A1 g ,1A1 g ,2E1 g , and 3A2 g for the VCp2,CrCp2,MnCp2,FeCp2,CoCp2 , and NiCp2, respectively.

  5. 'Clickable' ZnO nanocrystals: the superiority of a novel organometallic approach over the inorganic sol-gel procedure.

    PubMed

    Grala, Agnieszka; Wolska-Pietkiewicz, Małgorzata; Danowski, Wojciech; Wróbel, Zbigniew; Grzonka, Justyna; Lewiński, Janusz

    2016-05-31

    We demonstrate for the first time a highly efficient Cu(i)-catalyzed alkyne-azide cycloaddition reaction on the surface of ZnO nanocrystals with retention of their photoluminescence properties. Our comparative studies highlight the superiority of a novel self-supporting organometallic method for the preparation of brightly luminescent and well-passivated ZnO nanocrystals over the traditional sol-gel procedure.

  6. Effect of Cyclic Oxidation Exposure on Tensile Properties of a Pt-Aluminide Bond-Coated Ni-Base Superalloy

    NASA Astrophysics Data System (ADS)

    Zafir Alam, Md.; Hazari, N.; Varma, Vijay K.; Das, Dipak K.

    2011-12-01

    The tensile behavior of a directionally solidified (DS) Ni-base superalloy, namely, CM-247LC, was evaluated in the presence of a Pt-aluminide bond coat. The effect of the thermal cycling exposure of the coated alloy at 1373 K (1100 °C) on its tensile properties was examined. The tensile properties were evaluated at a temperature of 1143 K (870 °C). The presence of the bond coating caused an approximately 8 pct drop in the strength of the alloy in the as-coated condition. However, the coating did not appreciably affect the tensile ductility of the substrate alloy. The bond coat prevented oxidation-related surface damage to the superalloy during thermal cycling exposure in air at 1373 K (1100 °C). Such cyclic oxidation exposure (up to 750 hours) did not cause any further reduction in yield strength (YS) of the coated alloy. There was a marginal decrease in the ultimate tensile strength (UTS) with increased exposure duration. Because of the oxidation protection provided by the bond coat, the drastic loss in ductility of the alloy, which would have happened in the absence of the coating, was prevented.

  7. Synthesis and cyclic oxidation behavior of a (Ni, Pt) Al coating on a desulfurized Ni-base superalloy

    SciTech Connect

    Zhang, Y.; Lee, W.Y.; Haynes, J.A.; Wright, I.G.; Pint, B.A.; Cooley, K.M.; Liaw, P.K.

    1999-10-01

    The influences of sulfur impurities and Pt incorporation on the scale adhesion behavior of aluminide coatings were studied and compared. Low-sulfur NiAl coatings were prepared on a desulfurized, yttrium-free, single-crystal Ni-based superalloy by a modified version of a conventional aluminizing procedure based on chemical vapor deposition. The sulfur level in the resulting NiAl coatings was measured to be less than {approximately}0.5 ppmw by glow-discharge mass spectroscopy. Platinum-modified aluminide coatings were synthesized by first electroplating a thin layer of Pt({approximately}7 {micro}m) on the superalloy, followed by the same low-sulfur aluminizing procedure. The measured sulfur content in the (Ni,Pt)Al coating was substantially higher than that of the low-sulfur NiAl coating due to contamination during the Pt electroplating process. A very adherent {alpha}-Al{sub 2}O{sub 3} scale formed on the grain surfaces of the low-sulfur NiAl coating during cyclic oxidation testing at 1,150 C, but scale spallation eventually occurred over many of the NiAl grain boundaries. In contrast, despite the higher level of sulfur in the (NI,Pt)Al coating, a very adherent scale was formed over both the coating grain surfaces and grain boundaries during thermal cycling. These results suggest that Pt additions can mitigate the detrimental influence of sulfur on scale adhesion.

  8. Laser clad Ni-base alloy added nano- and micron-size CeO 2 composites

    NASA Astrophysics Data System (ADS)

    Zhang, Shi Hong; Li, Ming Xi; Cho, Tong Yul; Yoon, Jae Hong; Lee, Chan Gyu; He, Yi Zhu

    2008-07-01

    Micron-size Ni-base alloy (NBA) powders are mixed with both 1.5 wt% (%) micron-CeO 2 (m-CeO 2) and also 1.0-3.0% nano-CeO 2 (n-CeO 2) powders. These mixtures are coated on low carbon steel (Q235) by 2.0 kW CO 2 laser cladding. The effects on microstructures, microhardness and wear resistance of the coating by the addition of m- and n-CeO 2 powders to NBA (m- and n-CeO 2/NBA) have been investigated. Addition to the primary phases of γ-Ni, Cr 23C 6 and Ni 3B of NBA coating, CeNi 3 shows up both in m- and n-CeO 2/NBA coatings and CeNi 5 appears only in n-CeO 2/NBA coating. Directional dendrite and coarse equiaxed dendrite are grown in m-CeO 2/NBA coating from interface to central zone, whereas multi-oriented dendrite and fine equiaxed dendrite growth by addition of n-CeO 2. The microhardness and wear resistance of coatings are greatly improved by CeO 2 powder addition, and compared to the addition of 1.0% and 3.0%, 1.5% n-CeO 2/NBA is the best. Hardness and wear resistance of the coating improves with decreasing CeO 2 size from micron to nano.

  9. Effect of impregnation phases on the performance of Ni-based anodes for low temperature solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Liu, Zhangbo; Ding, Dong; Liu, Beibei; Guo, Weiwei; Wang, Wendong; Xia, Changrong

    2011-10-01

    Impregnated nanoparticles are very effective in improving the electrochemical performance of solid oxide fuel cell (SOFC) anodes possibly due to the extension of reaction sites and/or the enhancement of catalytic activity. In this work, samaria-doped ceria (SDC), pure ceria, samaria, and alumina oxides impregnated Ni-based anodes are fabricated to compare the site extending and the catalytic effects. Except for alumina, the impregnation of the other three nano-sized oxides could substantially enhance the performance of the anodes for the hydrogen oxidation reactions. Moreover, single cells with CeO2 and Sm2O3 impregnated anodes could exhibit as great performance as those with SDC impregnated anodes. When the impregnation loading reached the optimal value, 1.7 mmol cm-3, these cells exhibit very high performance, with peak power densities around 750 mW cm-2. The high performance of CeO2 and Sm2O3 impregnated anodes demonstrates that the improved performance are mainly attributed to the significantly improved electrochemical activities of the anodes, but not to the extension of triple-phase-boundary, and wet impregnation is indeed an alternative and effective technique to introduce these nano-sized catalytic active oxides into the anode configuration of SOFCs to enhance cell performance, stability and reliability.

  10. Deactivation Mechanisms of Ni-Based Tar Reforming Catalysts As Monitored by X-ray Absorption Spectroscopy

    SciTech Connect

    Yung, Matthew M.; Kuhn, John N.

    2010-12-06

    Deactivation mechanisms of alumina-supported, Ni-based catalysts for tar reforming in biomass-derived syngas were evaluated using extended X-ray absorption fine structure (EXAFS) spectroscopy. Catalysts were characterized before and after catalytic reaction cycles and regeneration procedures, which included oxidation by a mixture of steam and air, and reduction in hydrogen. Qualitative analysis of the EXAFS spectra revealed that oxidation of a portion of the Ni in the catalysts to form an oxide phase and/or a sulfide phase were likely scenarios that led to catalyst deactivation with time-on-stream and with increased reaction cycles. Deactivation through carbon deposition, phosphorus poisoning, or changes in particle size were deemed as unlikely causes. Quantitative analysis of the EXAFS spectra indicated sulfur poisoning occurred with time-on-stream, and the contaminating species could not be completely removed during the regeneration protocols. The results also verified that Ni-containing oxide phases (most likely a spinel also containing Mg and Al) formed and contributed to the deactivation. This study validates the need for developing catalyst systems that will protect Ni from sulfur poisoning and oxide formation at elevated reaction and regeneration temperatures.

  11. The effect of variations of cobalt content on the cyclic oxidation resistance of selected Ni-base superalloys

    NASA Technical Reports Server (NTRS)

    Barrett, C. A.

    1986-01-01

    Cobalt levels were systematically varied in the Ni-base turbine alloys U-700 (cast), U-700m(PM/HIP), Waspaloy, Mar-M-247, In-738, Nimonic-115, U-720, and SX-R-150. The cobalt levels ranged from 0 wt % to the nominal commercial content in each alloy. The alloys were tested in cyclic oxidation in static air at 1000, 1100 and 1150 C for 500, 200 and 100 hr respectively. An oxidation attack parameter, Ka derived from the specific weight change versus time data was used to evaluate the oxidation behavior of the alloys along with X-ray diffraction analysis of the surface oxides. The alloys tend to form either Cr2O3/chromite spinel or Al2O3/aluminate spinel depending on the CR/Al ratio in the alloys. Alloys with a ratio of 3.5 or higher tend to favor the Cr oxides while those under 3.0 form mostly Al oxides. In general the Al2O3/aluminate spinel forming alloys have the better oxidation resistance. Increased cobalt content lowers the scaling resistance of the higher Cr alloys while a 5.0 wt % Co content is optimum for the Al controlling alloys. The refractory metals, particularly Ta, appear beneficial to both types of oxides perhaps due to the formation of the omni-present trirutile Ni(Ta,Cb,Mo,W)2O6. Both scales break down as increasing amounts of NiO is formed.

  12. The effect of variations of cobalt content on the cyclic oxidation resistance of selected Ni-base superalloys

    NASA Technical Reports Server (NTRS)

    Barrett, Charles A.

    1987-01-01

    Cobalt levels were systematically varied in the Ni-base turbine alloys U-700 (cast), U-700m (PM/HIP), Waspaloy, Mar-M-247, In-738, Nimonic-115, U-720, and SX-R-150. the cobalt levels ranged from 0 wt pct to the nominal commercial content in each alloy. the alloys were tested in cyclic oxidation in static air at 1000, 1100 and 1150 C for 500, 200, and 100 hr, respectively. An oxidation attack parameter, Ka, derived from the specific weight change versus time data was used to evaluate the oxidation behavior of the alloys along with X-ray diffraction analysis of the surface oxides. The alloys tend to form either Cr2O3/chromite spinel or Al2O3/aluminate spinel depending on the Cr/Al ratio in the alloys. Alloys with a ratio of 3.5 or higher tend to favor the Cr oxides while those under 3.0 form mostly Al oxides. In general the Al2O3/aluminate spinel forming alloys have the better oxidation resistance. Increased cobalt content lowers the scaling resistance of the higher Cr allys while a 5.0 wt pct Co content is optimum for the Al controlling alloys. The refractory metals, particularly Ta, appear beneficial to both types of oxides, perhaps due to the formation of the omnipresent trirutile Ni(Ta, Cb, Mo, W)2O6. Both scales break down as increasing amounts of NiO are formed.

  13. Abrasive Wear Behavior of WC Reinforced Ni-BASED Composite Coating Sprayed and Fused by Oxy-Acetylene Flame

    NASA Astrophysics Data System (ADS)

    Wang, Qun; Chen, Zhenhua; Ding, Zhang Xiong; Chen, Ding

    Microstructure of WC reinforced Ni-based self-fluxing alloy composite coating sprayed and fused by oxy-acetylene flame was investigated by scanning electron microscopy and energy dispersive X-ray Spectrometry, X-ray diffraction, and transmission electron microscopy. The wear performance of the coating was studied by a MLS-225 wet sand rubber wheel abrasive wear tester at various loads and sizes of abrasive particles. Also, the wear resistance of the coating was compared with uncoated ASTM1020 steel. The results indicated that the coating is bonded metallurgically to the substrate and has a homogeneous microstructure composed of both coarse WC and fine carbide and boride grains such as Cr7C3, Cr23C6, and Ni2B which disperse uniformly in the matrix of γ-Ni solid solution and Ni3B. The worn mass loss of the coating and ASTM1020 steel both increased with the load and size of abrasive particles, also, the coating has exhibited excellent abrasive wear resistance compared with ASTM1020 steel.

  14. Tailoring the physical properties of Ni-based single-phase equiatomic alloys by modifying the chemical complexity.

    PubMed

    Jin, K; Sales, B C; Stocks, G M; Samolyuk, G D; Daene, M; Weber, W J; Zhang, Y; Bei, H

    2016-02-01

    Equiatomic alloys (e.g. high entropy alloys) have recently attracted considerable interest due to their exceptional properties, which might be closely related to their extreme disorder induced by the chemical complexity. In order to understand the effects of chemical complexity on their fundamental physical properties, a family of (eight) Ni-based, face-center-cubic (FCC), equiatomic alloys, extending from elemental Ni to quinary high entropy alloys, has been synthesized, and their electrical, thermal, and magnetic properties are systematically investigated in the range of 4-300 K by combining experiments with ab initio Korring-Kohn-Rostoker coherent-potential-approximation (KKR-CPA) calculations. The scattering of electrons is significantly increased due to the chemical (especially magnetic) disorder. It has weak correlation with the number of elements but strongly depends on the type of elements. Thermal conductivities of the alloys are largely lower than pure metals, primarily because the high electrical resistivity suppresses the electronic thermal conductivity. The temperature dependence of the electrical and thermal transport properties is further discussed, and the magnetization of five alloys containing three or more elements is measured in magnetic fields up to 4 T.

  15. Real-time microstructure imaging by Laue microdiffraction: A sample application in laser 3D printed Ni-based superalloys

    PubMed Central

    Zhou, Guangni; Zhu, Wenxin; Shen, Hao; Li, Yao; Zhang, Anfeng; Tamura, Nobumichi; Chen, Kai

    2016-01-01

    Synchrotron-based Laue microdiffraction has been widely applied to characterize the local crystal structure, orientation, and defects of inhomogeneous polycrystalline solids by raster scanning them under a micro/nano focused polychromatic X-ray probe. In a typical experiment, a large number of Laue diffraction patterns are collected, requiring novel data reduction and analysis approaches, especially for researchers who do not have access to fast parallel computing capabilities. In this article, a novel approach is developed by plotting the distributions of the average recorded intensity and the average filtered intensity of the Laue patterns. Visualization of the characteristic microstructural features is realized in real time during data collection. As an example, this method is applied to image key features such as microcracks, carbides, heat affected zone, and dendrites in a laser assisted 3D printed Ni-based superalloy, at a speed much faster than data collection. Such analytical approach remains valid for a wide range of crystalline solids, and therefore extends the application range of the Laue microdiffraction technique to problems where real-time decision-making during experiment is crucial (for instance time-resolved non-reversible experiments). PMID:27302087

  16. Optical and analytical electron microscopy of ductility-dip cracking in Ni-base filler metal 52 -- Initial studies

    SciTech Connect

    Cola, M.J.; Teter, D.F.

    1998-01-01

    Microcharacterization studies were performed on weld-metal microstructures of a Ni-base filler metal. Specimens were taken from the fusion zone and the weld-metal heat-affected zone of transverse- and spot-Varestraint welds. The filler metal was first deposited onto a steel substrate by hot-wire, gas tungsten arc welding before specimen removal. Optical microscopy indicates the crack morphology is intergranular and is along high-angle, migrated grain boundaries. At low magnifications, scanning electron microscopy reveals a relatively smooth fracture surface. However, at higher magnifications the grain faces exhibit microductility. Analytical electron microscopy reveals high-angle, migrated grain boundaries decorated with MC (Ti, Cr) and M{sub 23}C{sub 6} (Cr, Ni, Fe) precipitates ranging from 10 to 200 n. Auger electron spectroscopy of pre-strained Gleeble specimens fractured in situ revealed internal ductility-dip cracks decorated with magnesium aluminate (MgAl{sub 2}O{sub 4}) spinel particles (1,000 nm).

  17. Tailoring the physical properties of Ni-based single-phase equiatomic alloys by modifying the chemical complexity

    SciTech Connect

    Jin, Ke; Sales, Brian C.; Stocks, George Malcolm; Samolyuk, German D.; Daene, Markus; Weber, William J.; Zhang, Yanwen; Bei, Hongbin

    2016-02-01

    We discovered that equiatomic alloys (e.g. high entropy alloys) have recently attracted considerable interest due to their exceptional properties, which might be closely related to their extreme disorder induced by the chemical complexity. To understand the effects of chemical complexity on their fundamental physical properties, a family of (eight) Ni-based, face-center-cubic (FCC), equiatomic alloys, extending from elemental Ni to quinary high entropy alloys, has been synthesized, and their electrical, thermal, and magnetic properties are systematically investigated in the range of 4–300 K by combining experiments with ab initio Korring-Kohn-Rostoker coherent-potential-approximation (KKR-CPA) calculations. The scattering of electrons is significantly increased due to the chemical (especially magnetic) disorder. It has weak correlation with the number of elements but strongly depends on the type of elements. Thermal conductivities of the alloys are largely lower than pure metals, primarily because the high electrical resistivity suppresses the electronic thermal conductivity. Moreover, the temperature dependence of the electrical and thermal transport properties is further discussed, and the magnetization of five alloys containing three or more elements is measured in magnetic fields up to 4 T.

  18. Detached Melt Nucleation during Diffusion Brazing of a Technical Ni-based Superalloy: A Phase-Field Study

    NASA Astrophysics Data System (ADS)

    Böttger, B.; Apel, M.; Laux, B.; Piegert, S.

    2015-06-01

    Advanced solidification processes like welding, soldering, and brazing are often characterized by their specific solidification conditions. But they also may include different types of melting processes which themselves are strongly influenced by the initial microstructures and compositions of the applied materials and therefore are decisive for the final quality and mechanical properties of the joint. Such melting processes are often not well- understood because - compared to other fields of solidification science - relatively little research has been done on melting by now. Also, regarding microstructure simulation, melting has been strongly neglected in the past, although this process is substantially different from solidification due to the reversed diffusivities of the involved phases. In this paper we present phase-field simulations showing melting, solidification and precipitation of intermetallic phases during diffusion brazing of directionally solidified and heat-treated high-alloyed Ni- based gas turbine blade material using different boron containing braze alloys. Contrary to the common belief, melting of the base material is not always planar and can be further accompanied by detached nucleation and growth of a second liquid phase inside the base material leading to polycrystalline morphologies of the joint after solidification. These findings are consistent with results from brazed laboratory samples, which were characterized by EDX and optical microscopy, and can be explained in terms of specific alloy thermodynamics and inter-diffusion kinetics. Consequences of the gained new understanding for brazing of high- alloyed materials are discussed.

  19. Deactivation mechanisms of Ni-based tar reforming catalysts as monitored by X-ray absorption spectroscopy.

    PubMed

    Yung, Matthew M; Kuhn, John N

    2010-11-02

    Deactivation mechanisms of alumina-supported, Ni-based catalysts for tar reforming in biomass-derived syngas were evaluated using extended X-ray absorption fine structure (EXAFS) spectroscopy. Catalysts were characterized before and after catalytic reaction cycles and regeneration procedures, which included oxidation by a mixture of steam and air, and reduction in hydrogen. Qualitative analysis of the EXAFS spectra revealed that oxidation of a portion of the Ni in the catalysts to form an oxide phase and/or a sulfide phase were likely scenarios that led to catalyst deactivation with time-on-stream and with increased reaction cycles. Deactivation through carbon deposition, phosphorus poisoning, or changes in particle size were deemed as unlikely causes. Quantitative analysis of the EXAFS spectra indicated sulfur poisoning occurred with time-on-stream, and the contaminating species could not be completely removed during the regeneration protocols. The results also verified that Ni-containing oxide phases (most likely a spinel also containing Mg and Al) formed and contributed to the deactivation. This study validates the need for developing catalyst systems that will protect Ni from sulfur poisoning and oxide formation at elevated reaction and regeneration temperatures.

  20. Effect of La2O3 on High-Temperature Oxidation Resistance of Electrospark Deposited Ni-BASED Coatings

    NASA Astrophysics Data System (ADS)

    Gao, Yuxin; Yi, Jian; Fang, Zhigang; Cheng, Hu

    2014-08-01

    The oxidation tests of electrospark deposited Ni-based coatings without and with 2.5 wt.% La2O3 were conducted at 960°C in air for 100 h. The oxidation kinetic of the coatings was studied by testing the weight gain. The phase structures and morphologies of the oxidized coatings were investigated by XRD and SEM. The experimental results show that the coatings with 2.5 wt.% La2O3 exhibits excellent high-temperature oxidation resistance including low oxidation rate and improved spallation resistance, due to the formation of a denser and more adherent oxide scale compared with that without La2O3. The effects of La2O3 on the oxidation resistance include the following two aspects: First, refinement of the coating grains promotes the selective oxidation of Cr, leading to the formation of protective chromia scale in a short time, and second, refinement of the oxide grains enhances the high-temperature creep rate, resulting in decrease of inner stress and improvement of spallation resistance of the oxide layer.

  1. Direct methane solid oxide fuel cells based on catalytic partial oxidation enabling complete coking tolerance of Ni-based anodes

    NASA Astrophysics Data System (ADS)

    Lee, Daehee; Myung, Jaeha; Tan, Jeiwan; Hyun, Sang-Hoon; Irvine, John T. S.; Kim, Joosun; Moon, Jooho

    2017-03-01

    Solid oxide fuel cells (SOFCs) can oxidize diverse fuels by harnessing oxygen ions. Benefited by this feature, direct utilization of hydrocarbon fuels without external reformers allows for cost-effective realization of SOFC systems. Superior hydrocarbon reforming catalysts such as nickel are required for this application. However, carbon coking on nickel-based anodes and the low efficiency associated with hydrocarbon fueling relegate these systems to immature technologies. Herein, we present methane-fueled SOFCs operated under conditions of catalytic partial oxidation (CPOX). Utilizing CPOX eliminates carbon coking on Ni and facilitates the oxidation of methane. Ni-gadolinium-doped ceria (GDC) anode-based cells exhibit exceptional power densities of 1.35 W cm-2 at 650 °C and 0.74 W cm-2 at 550 °C, with stable operation over 500 h, while the similarly prepared Ni-yttria stabilized zirconia anode-based cells exhibit a power density of 0.27 W cm-2 at 650 °C, showing gradual degradation. Chemical analyses suggest that combining GDC with the Ni anode prevents the oxidation of Ni due to the oxygen exchange ability of GDC. In addition, CPOX operation allows the usage of stainless steel current collectors. Our results demonstrate that high-performance SOFCs utilizing methane CPOX can be realized without deterioration of Ni-based anodes using cost-effective current collectors.

  2. Observations on the oxidation of Mn-modified Ni-base Haynes 230 alloy under SOFC exposure conditions

    SciTech Connect

    Yang, Z Gary; Xia, Gordon; Stevenson, Jeffry W.; Singh, Prabhakar

    2005-07-01

    The commercial Ni-base Haynes 230 alloy (Ni-Cr-Mo-W-Mn) was modified with two increased levels of Mn (1 and 2 wt per cent) and evaluated for its oxidation resistance under simulated SOFC interconnect exposure conditions. Oxidation rate, oxide morphology, oxide conductivity and thermal expansion were measured and compared with commercial Haynes 230. It was observed that additions of higher levels of Mn to the bulk alloy facilitated the formation of a bi-layered oxide scale that was comprised of an outer M3O4 (M=Mn, Cr, Ni) spinel-rich layer at the oxide – gas interface over a Cr2O3-rich sub-layer at the metal – oxide interface. The modified alloys showed higher oxidation rates and the formation of thicker oxide scales compared to the base alloy. The formation of a spinel-rich top layer improved the scale conductivity, especially during the early stages of the oxidation, but the higher scale growth rate resulted in an increase in the area-specific electrical resistance over time. Due to their face-centered cubic crystal structure, both commercial and modified alloys demonstrated a coefficient of thermal expansion that was higher than that of typical anode-supported and electrolyte-supported SOFCs.

  3. Initial assessment of Ni-base alloy performance in 0.1 MPa and supercritical CO2

    DOE PAGES

    Pint, B. A.; Keiser, J. R.

    2015-09-25

    There is considerable interest in increasing the working temperature of both open and closed supercritical CO2 (sCO2) cycles to ≥700 °C. At these temperatures, it is unlikely that any Fe-base alloys have suitable strength and therefore the focus is on Ni-base alloys for this application. To begin addressing the lack of compatibility data under these conditions, initial work exposed a wide range of candidate alloys in 500-h exposures at 20 MPa (200 bar) CO2 at 650 -750 °C in high purity CO2. In general, the reaction products were thin and protective in these exposures. A smaller group of alloy couponsmore » focusing on chromia- and alumina-forming alloys was exposed for 500h in 0.1 MPa (1bar) air, CO2, CO2+O2 and CO2+H2O for comparison. Thus, the thin surface oxides formed were very similar to those formed at high pressure and no clear detrimental effect of CO2 oxidation or O2 or H2O impurities could be observed in these exposures.« less

  4. Real-time microstructure imaging by Laue microdiffraction: A sample application in laser 3D printed Ni-based superalloys

    NASA Astrophysics Data System (ADS)

    Zhou, Guangni; Zhu, Wenxin; Shen, Hao; Li, Yao; Zhang, Anfeng; Tamura, Nobumichi; Chen, Kai

    2016-06-01

    Synchrotron-based Laue microdiffraction has been widely applied to characterize the local crystal structure, orientation, and defects of inhomogeneous polycrystalline solids by raster scanning them under a micro/nano focused polychromatic X-ray probe. In a typical experiment, a large number of Laue diffraction patterns are collected, requiring novel data reduction and analysis approaches, especially for researchers who do not have access to fast parallel computing capabilities. In this article, a novel approach is developed by plotting the distributions of the average recorded intensity and the average filtered intensity of the Laue patterns. Visualization of the characteristic microstructural features is realized in real time during data collection. As an example, this method is applied to image key features such as microcracks, carbides, heat affected zone, and dendrites in a laser assisted 3D printed Ni-based superalloy, at a speed much faster than data collection. Such analytical approach remains valid for a wide range of crystalline solids, and therefore extends the application range of the Laue microdiffraction technique to problems where real-time decision-making during experiment is crucial (for instance time-resolved non-reversible experiments).

  5. Tailoring the physical properties of Ni-based single-phase equiatomic alloys by modifying the chemical complexity

    DOE PAGES

    Jin, Ke; Sales, Brian C.; Stocks, George Malcolm; ...

    2016-02-01

    We discovered that equiatomic alloys (e.g. high entropy alloys) have recently attracted considerable interest due to their exceptional properties, which might be closely related to their extreme disorder induced by the chemical complexity. To understand the effects of chemical complexity on their fundamental physical properties, a family of (eight) Ni-based, face-center-cubic (FCC), equiatomic alloys, extending from elemental Ni to quinary high entropy alloys, has been synthesized, and their electrical, thermal, and magnetic properties are systematically investigated in the range of 4–300 K by combining experiments with ab initio Korring-Kohn-Rostoker coherent-potential-approximation (KKR-CPA) calculations. The scattering of electrons is significantly increased duemore » to the chemical (especially magnetic) disorder. It has weak correlation with the number of elements but strongly depends on the type of elements. Thermal conductivities of the alloys are largely lower than pure metals, primarily because the high electrical resistivity suppresses the electronic thermal conductivity. Moreover, the temperature dependence of the electrical and thermal transport properties is further discussed, and the magnetization of five alloys containing three or more elements is measured in magnetic fields up to 4 T.« less

  6. Predicting minimum Al concentrations for protective scale fromation on Ni-base alloys. I - Isothermal oxidation. II - Cyclic oxidation

    NASA Technical Reports Server (NTRS)

    Nesbitt, James A.

    1989-01-01

    Criteria proposed to predict the minimum bulk Al concentration for the formation of protective Al2O3 scales on Ni-based alloys during isothermal oxidation (two criteria proposed by Wagner, 1952 and 1959) and cyclic oxidation (the criteria proposed by Wahl, 1983, and Whittle, 1972/Wahl, 1983) were applied to Ni-Al and Ni-Cr-Al(Zr) alloys, respectively. It is shown that the first Wagner (1952) criterion underpredicted, by a factor of 3, the experimentally observed minimum Al concentration for the formation of an external Al2O3 scale on Ni-Al alloys at 1200 C; the second Wagner criterion predicted a transition from internal oxidation to continuous Al2O3 formation in good agreement with experimentally observed concentrations. It was also found that the two criteria for an Al2O3 scale formation during cyclic oxidation of Ni-Cr-Al(Zr) alloys were inadequate to predict the minimum Al concentration necessary for repeated formation of an Al2O3 scale, regardless of the adherence of the scale.

  7. Thin Co/Ni-based bottom pinned spin-transfer torque magnetic random access memory stacks with high annealing tolerance

    NASA Astrophysics Data System (ADS)

    Tomczak, Y.; Swerts, J.; Mertens, S.; Lin, T.; Couet, S.; Liu, E.; Sankaran, K.; Pourtois, G.; Kim, W.; Souriau, L.; Van Elshocht, S.; Kar, G.; Furnemont, A.

    2016-01-01

    Spin-transfer torque magnetic random access memory (STT-MRAM) is considered as a replacement for next generation embedded and stand-alone memory applications. One of the main challenges in the STT-MRAM stack development is the compatibility of the stack with CMOS process flows in which thermal budgets up to 400 °C are applied. In this letter, we report on a perpendicularly magnetized MgO-based tunnel junction (p-MTJ) on a thin Co/Ni perpendicular synthetic antiferromagnetic layer with high annealing tolerance. Tunnel magneto resistance (TMR) loss after annealing occurs when the reference layer loses its perpendicular magnetic anisotropy due to reduction of the CoFeB/MgO interfacial anisotropy. A stable Co/Ni based p-MTJ stack with TMR values of 130% at resistance-area products of 9 Ω μm2 after 400 °C anneal is achieved via moment control of the Co/Ta/CoFeB reference layer. Thinning of the CoFeB polarizing layer down to 0.8 nm is the key enabler to achieve 400 °C compatibility with limited TMR loss. Thinning the Co below 0.6 nm leads to a loss of the antiferromagnetic interlayer exchange coupling strength through Ru. Insight into the thickness and moment engineering of the reference layer is displayed to obtain the best magnetic properties and high thermal stability for thin Co/Ni SAF-based STT-MRAM stacks.

  8. Tailoring the physical properties of Ni-based single-phase equiatomic alloys by modifying the chemical complexity

    NASA Astrophysics Data System (ADS)

    Jin, K.; Sales, B. C.; Stocks, G. M.; Samolyuk, G. D.; Daene, M.; Weber, W. J.; Zhang, Y.; Bei, H.

    2016-02-01

    Equiatomic alloys (e.g. high entropy alloys) have recently attracted considerable interest due to their exceptional properties, which might be closely related to their extreme disorder induced by the chemical complexity. In order to understand the effects of chemical complexity on their fundamental physical properties, a family of (eight) Ni-based, face-center-cubic (FCC), equiatomic alloys, extending from elemental Ni to quinary high entropy alloys, has been synthesized, and their electrical, thermal, and magnetic properties are systematically investigated in the range of 4–300 K by combining experiments with ab initio Korring-Kohn-Rostoker coherent-potential-approximation (KKR-CPA) calculations. The scattering of electrons is significantly increased due to the chemical (especially magnetic) disorder. It has weak correlation with the number of elements but strongly depends on the type of elements. Thermal conductivities of the alloys are largely lower than pure metals, primarily because the high electrical resistivity suppresses the electronic thermal conductivity. The temperature dependence of the electrical and thermal transport properties is further discussed, and the magnetization of five alloys containing three or more elements is measured in magnetic fields up to 4 T.

  9. Effect of Creep and Oxidation on Reduced Creep-Fatigue life of Ni-based Alloy 617 at 850 C

    SciTech Connect

    Chen, Xiang; Yang, Zhiqing; Sokolov, Mikhail A; ERDMAN III, DONALD L; Mo, Kun; Stubbins, James

    2014-01-01

    Low cycle fatigue (LCF) and creep fatigue testing of Ni-based alloy 617 was carried out at 850 C. Compared with its LCF life, the material s creep fatigue life decreases to different extents depending on test conditions. To elucidate the microstructure-fatigue property relationship for alloy 617 and the effect of creep and oxidation on its fatigue life, systematic microstructural investigations were carried out using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electron backscatter diffraction (EBSD). In LCF tests, as the total strain range increased, deformations concentrated near high angle grain boundaries (HAGBs). The strain hold period in the creep fatigue tests introduced additional creep damage to the material, which revealed the detrimental effect of the strain hold time on the material fatigue life in two ways. First, the strain hold time enhanced the localized deformation near HAGBs, resulting in the promotion of intergranular cracking of alloy 617. Second, the strain hold time encouraged grain boundary sliding, which resulted in interior intergranular cracking of the material. Oxidation accelerated the initiation of intergranular cracking in alloy 617. In the crack propagation stage, if oxidation was promoted and the cyclic oxidation damage was greater than the fatigue damage, oxidation-assisted intergranular crack growth resulted in a significant reduction in the material s fatigue life.

  10. Low cycle fatigue and creep-fatigue behavior of Ni-based alloy 230 at 850 C

    SciTech Connect

    Chen, Xiang; Yang, Zhiqing; Sokolov, Mikhail A; ERDMAN III, DONALD L; Mo, Kun; Stubbins, James

    2013-01-01

    Strain-controlled low cycle fatigue (LCF) and creep-fatigue testing of Ni-based alloy 230 were carried out at 850 C. The material creep-fatigue life decreased compared with its low cycle fatigue life at the same total strain range. Longer hold time at peak tensile strain further reduced the material creep-fatigue life. Based on the electron backscatter diffraction, a novel material deformation characterization method was applied, which revealed that in low cycle fatigue testing as the total strain range increased, the deformation was segregated to grain boundaries since the test temperature was higher than the material equicohesive temperature and grain boundaries became weaker regions compared with grains. Creep-fatigue tests enhanced the localized deformation, resulting in material interior intergranular cracking, and accelerated material damage. Precipitation in alloy 230 helped slip dispersion, favorable for fatigue property, but grain boundary cellular precipitates formed after material exposure to the elevated temperature had a deleterious effect on the material low cycle fatigue and creep-fatigue property.

  11. Surface organometallic chemistry on metals: Evidence for a new surface organometallic material Rh(Sn(C{sub 4}H{sub 9}){sub x}){sub y} obtained by controlled hydrogenolysis of Sn(C{sub 4}H{sub 9}){sub 4} on Rh/SiO{sub 2}

    SciTech Connect

    Didillon, B.; Clause, O.; Lefevbre, F.; Lamb, H.; Houtman, C.; Shay, T.; Candy, J.P.; Basset, J.M.

    1993-12-31

    It is shown that it is possible to graft organometallic fragments, namely Sn(C{sub 4}H{sub 9}){sub x}(x=1,2,3) at the surface of a rhodium particle supported on silica. These organometallic fragments are obtained by selective hydrogenolysis of Sn(C{sub 4}H{sub 9}){sub 4} on a Rhodium/silica catalyst. They are thermally stable on the particle up to a temperature of 423 K. The surface organometallic fragments have been characterized by micro-analytical data. Electron microscopy (CTEM and STEM), infrared spectroscopy, XPS Analysis, Moessbauer spectroscopy, MAS{sup 13}C NMR, EXAFS and molecular modeling. Depending on experimental conditions, it is possible to propose various surface structures for the organometallic fragments. However, the most likely fragment can be represented by the general formula: Rh{sub 8}Sn[Sn(C{sub 4}H{sub 9}){sub 3}]{sub 2}.

  12. Gas phase studies of the Pesci decarboxylation reaction: synthesis, structure, and unimolecular and bimolecular reactivity of organometallic ions.

    PubMed

    O'Hair, Richard A J; Rijs, Nicole J

    2015-02-17

    CONSPECTUS: Decarboxylation chemistry has a rich history, and in more recent times, it has been recruited in the quest to develop cheaper, cleaner, and more efficient bond-coupling reactions. Thus, over the past two decades, there has been intense investigation into new metal-catalyzed reactions of carboxylic substrates. Understanding the elementary steps of metal-mediated transformations is at the heart of inventing new reactions and improving the performance of existing ones. Fortunately, during the same time period, there has been a convergence in mass spectrometry (MS) techniques, which allows these catalytic processes to be examined efficiently in the gas phase. Thus, electrospray ionization (ESI) sources have been combined with ion-trap mass spectrometers, which in turn have been modified to either accept radiation from tunable OPO lasers for spectroscopy based structural assignment of ions or to allow the study of ion-molecule reactions (IMR). The resultant "complete" gas-phase chemical laboratories provide a platform to study the elementary steps of metal-catalyzed decarboxylation reactions in exquisite detail. In this Account, we illustrate how the powerful combination of ion trap mass spectrometry experiments and DFT calculations can be systematically used to examine the formation of organometallic ions and their chemical transformations. Specifically, ESI-MS allows the transfer of inorganic carboxylate complexes, [RCO2M(L)n](x), (x = charge) from the condensed to the gas phase. These mass selected ions serve as precursors to organometallic ions [RM(L)n](x) via neutral extrusion of CO2, accessible by slow heating in the ion trap using collision induced dissociation (CID). This approach provides access to an array of organometallic ions with well-defined stoichiometry. In terms of understanding the decarboxylation process, we highlight the role of the metal center (M), the organic group (R), and the auxiliary ligand (L), along with cluster nuclearity, in

  13. The Effect of CeO2 Addition on the Microstructure and Properties of Ni-Based Flame-Spray Coatings

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenyu; Liang, Bunv; Guo, Hongjian

    2014-04-01

    Ni-based alloy with different amount of CeO2 powders were flame sprayed and melted onto 1045 carbon steel substrate. Microstructure and properties of the coatings were studied by XRD, field emission gun scanning electron microscope (FEGSEM) and SEM analyses. The wear behavior of the coatings was investigated under dry sliding wear conditions, and was compared with that of the coatings without CeO2, The results show that the microstructure of the coating with CeO2 differs widely from the coating without CeO2, the novel microstructure is beneficial for wear resistance. Abrasive wear tests without lubricant and analysis of the worn surfaces revealed that the Ni-based alloy coatings with the addition of 0.8% CeO2 exhibit higher wear resistance.

  14. Performance of chromia- and alumina-forming Fe- and Ni-base alloys exposed to metal dusting environments: The effect of water vapor and temperature

    DOE PAGES

    Rouaix-Vande Put, Aurelie; Unocic, Kinga A.; Brady, Michael P.; ...

    2015-11-18

    Fe- and Ni-base alloys including an alumina-forming austenitic alloy were exposed for 500 h under metal dusting environments with varying temperature, gas composition and total pressure. For one H2–CO–CO2–H2O environment, the increase in temperature from 550 to 750 °C generally decreased metal dusting. When H2O was added to a H2–CO–CO2 environment at 650 °C, the metal dusting attack was reduced. Even after 5000 h at a total pressure of 9.1 atm with 20%H2O, the higher alloyed specimens retained a thin protective oxide. Lastly, for gas mixtures containing little or no H2O, the Fe-base alloys were less resistant to metal dustingmore » than Ni-base alloys.« less

  15. The nonlinear unloading behavior of a typical Ni-based superalloy during hot deformation: a unified elasto-viscoplastic constitutive model

    NASA Astrophysics Data System (ADS)

    Chen, Ming-Song; Lin, Y. C.; Li, Kuo-Kuo; Chen, Jian

    2016-09-01

    In authors' previous work (Chen et al. in Appl Phys A. doi: 10.1007/s00339-016-0371-6, 2016), the nonlinear unloading behavior of a typical Ni-based superalloy was investigated by hot compressive experiments with intermediate unloading-reloading cycles. The characters of unloading curves were discussed in detail, and a new elasto-viscoplastic constitutive model was proposed to describe the nonlinear unloading behavior of the studied Ni-based superalloy. Still, the functional relationships between the deformation temperature, strain rate, pre-strain and the parameters of the proposed constitutive model need to be established. In this study, the effects of deformation temperature, strain rate and pre-strain on the parameters of the new constitutive model proposed in authors' previous work (Chen et al. 2016) are analyzed, and a unified elasto-viscoplastic constitutive model is proposed to predict the unloading behavior at arbitrary deformation temperature, strain rate and pre-strain.

  16. Deformation-phase transformation coupling mechanism of white layer formation in high speed machining of FGH95 Ni-based superalloy

    NASA Astrophysics Data System (ADS)

    Du, Jin; Liu, zhanqiang; Lv, Shaoyu

    2014-02-01

    Ni-based superalloy represents a significant metal portion of the aircraft critical structural and engine components. When these critical structural components in aerospace industry are manufactured with the objective to reach high reliability levels and excellent service performance, surface integrity is one of the most relevant parameter used for evaluating the quality of finish machined surfaces. In the study of surface integrity, the formation white layer is a very important research topic. The formation of white layer on the Ni-based superalloy machined surface will reduce the machined parts service performance and fatigue life. This paper was conducted to determine the effects of cutting speed on white layer formation in high speed machining of FGH95 Ni-based superalloy. Optical microscope, scanning electron microscope and X-ray diffraction were employed to analyze the elements and microstructures of white layer and bulk materials. The statistical analysis for grain numbers was executed to study the influence of cutting speed on the grain refinement in the machined surface. The investigation results showed that white layer exhibits significantly different microstructures with the bulk materials. It shows densification, no obvious structural features characteristic. The microstructure and phase of Ni-based solid solution changed during cutting process. The increase of cutting speed causes the increase of white layer thickness when the cutting speed is less than 2000 m/min. However, white layer thickness reduces with the cutting speed further increase. The higher the cutting speed, the more serious grains refinement in machined surface. 2-D FEM for machining FGH95 were carried out to simulate the cutting process and obtained the cutting temperature field, cutting strain field and strain rate field. The impact mechanisms of cutting temperature, cutting strain and strain rates on white layer formation were analyzed. At last, deformation-phase transformation

  17. Development of a High Chromium Ni-Base Filler Metal Resistant to Ductility Dip Cracking and Solidification Cracking

    NASA Astrophysics Data System (ADS)

    Hope, Adam T.

    Many nuclear reactor components previously constructed with Ni-based alloys containing 20 wt% Cr have been found to be susceptible to stress corrosion cracking. The nuclear power industry now uses high chromium (˜30wt%) Ni-based filler metals to mitigate stress corrosion cracking. Current alloys are plagued with weldability issues, either solidification cracking or ductility dip cracking (DDC). Solidification cracking is related to solidification temperature range and the DDC is related to the fraction eutectic present in the microstructure. It was determined that an optimal alloy should have a solidification temperature range less than 150°C and at least 2% volume fraction eutectic. Due to the nature of the Nb rich eutectic that forms, it is difficult to avoid both cracking types simultaneously. Through computational modeling, alternative eutectic forming elements, Hf and Ta, have been identified as replacements for Nb in such alloys. Compositions have been optimized through a combination of computational and experimental techniques combined with a design of experiment methodology. Small buttons were melted using commercially pure materials in a copper hearth to obtain the desired compositions. These buttons were then subjected to a gas tungsten arc spot weld. A type C thermocouple was used to acquire the cooling history during the solidification process. The cooling curves were processed using Single Sensor Differential Thermal Analysis to determine the solidification temperature range, and indicator of solidification cracking susceptibility. Metallography was performed to determine the fraction eutectic present, an indicator of DDC resistance. The optimal level of Hf to resist cracking was found to be 0.25 wt%. The optimal level of Ta was found to be 4 wt%. gamma/MC type eutectics were found to form first in all Nb, Ta, and Hf-bearing compositions. Depending on Fe and Cr content, gamma/Laves eutectic was sometimes found in Nb and Ta-bearing compositions, while

  18. Single-Molecule Fluorescence Imaging for Studying Organic, Organometallic, and Inorganic Reaction Mechanisms

    SciTech Connect

    Blum, Suzanne A.

    2016-05-24

    The reactive behavior of individual molecules is seldom observed, because we usually measure the average properties of billions of molecules. What we miss is important: the catalytic activity of less than 1% of the molecules under observation can dominate the outcome of a chemical reaction seen at a macroscopic level. Currently available techniques to examine reaction mechanisms (such as nuclear magnetic resonance spectroscopy and mass spectrometry) study molecules as an averaged ensemble. These ensemble techniques are unable to detect minor components (under ~1%) in mixtures or determine which components in the mixture are responsible for reactivity and catalysis. In the field of mechanistic chemistry, there is a resulting heuristic device that if an intermediate is very reactive in catalysis, it often cannot be observed (termed “Halpern’s Rule” ). Ultimately, the development of single-molecule imaging technology could be a powerful tool to observe these “unobservable” intermediates and active catalysts. Single-molecule techniques have already transformed biology and the understanding of biochemical processes. The potential of single-molecule fluorescence microscopy to address diverse chemical questions, such as the chemical reactivity of organometallic or inorganic systems with discrete metal complexes, however, has not yet been realized. In this respect, its application to chemical systems lags significantly behind its application to biophysical systems. This transformative imaging technique has broad, multidisciplinary impact with the potential to change the way the chemistry community studies reaction mechanisms and reactivity distributions, especially in the core area of catalysis.

  19. Atmospheric pressure synthesis of photoluminescent hybrid materials by sequential organometallic vapor infiltration into polyethylene terephthalate fibers

    SciTech Connect

    Akyildiz, Halil I.; Mousa, Moataz Bellah M.; Jur, Jesse S.

    2015-01-28

    Exposing a polymer to sequential organometallic vapor infiltration (SVI) under low pressure conditions can significantly modify the polymer's chemical, mechanical, and optical properties. We demonstrate that SVI of trimethylaluminum into polyethylene terephthalate (PET) can also proceed readily at atmospheric pressure, and at 60 °C the extent of reaction determined by mass uptake is independent of pressure between 2.5 Torr and 760 Torr. At 120 °C, however, the mass gain is 50% larger at 2.5 Torr relative to that at 760 Torr, indicating that the precursor diffusion in the chamber and fiber matrix decreases at higher source pressure. Mass gain decreases, in general, as the SVI process temperature increases both at 2.5 Torr and 760 Torr attributed to the faster reaction kinetics forming a barrier layer, which prevents further diffusion of the reactive species. The resulting PET/Al-O{sub x} product shows high photoluminescence compared to untreated fibers. A physical mask on the polymer during infiltration at 760 Torr is replicated in the underlying polymer, producing an image in the polymer that is visible under UV illumination. Because of the reduced precursor diffusivity during exposure at 760 Torr, the image shows improved resolution compared to SVI performed under typical 2.5 Torr conditions.

  20. Active photonic devices based on colloidal semiconductor nanocrystals and organometallic halide perovskites

    NASA Astrophysics Data System (ADS)

    Suárez Alvarez, Isaac

    2016-10-01

    Semiconductor nanocrystals have arisen as outstanding materials to develop a new generation of optoelectronic devices. Their fabrication under simple and low cost colloidal chemistry methods results in cheap nanostructures able to provide a wide range of optical functionalities. Their attractive optical properties include a high absorption cross section below the band gap, a high quantum yield emission at room temperature, or the capability of tuning the band-gap with the size or the base material. In addition, their solution process nature enables an easy integration on several substrates and photonic structures. As a consequence, these nanoparticles have been extensively proposed to develop several photonic applications, such as detection of light, optical gain, generation of light or sensing. This manuscript reviews the great effort undertaken by the scientific community to construct active photonic devices based on these nanoparticles. The conditions to demonstrate stimulated emission are carefully studied by comparing the dependence of the optical properties of the nanocrystals with their size, shape and composition. In addition, this paper describes the design of different photonic architectures (waveguides and cavities) to enhance the generation of photoluminescence, and hence to reduce the threshold of optical gain. Finally, semiconductor nanocrystals are compared to organometallic halide perovskites, as this novel material has emerged as an alternative to colloidal nanoparticles.

  1. Magnetically-induced electric polarization in an organo-metallic magnet

    SciTech Connect

    Zapf, W S; Fabris, F W; Balakirev, F F; Francoual, S M; Kenzelmann, M; Chen, Y

    2009-01-01

    The coupling between magnetic order and ferroelectricity has been under intense investigation in a wide range of transition metal oxides. The strongest coupling is obtained in so-called magnetically induced multiferroics where ferroelectricity arises directly from magnetic order that breaks inversion symmetry. However, it has been difficult to find non-oxide based materials in which these effects occur. Here we present a study of copper dimethyl sulfoxide dichloride (CDC), an organometallic quantum magnet containing S =1/1 Cu spins, in which a switchable electric polarization arises from field-tuned magnetic order. Fast magnetic field pulses allow us to perform sensitive measurements of the electric polarization and demonstrate that the electric state is present only if the magnetic order is non-collinear. Furthermore, we show that the electric polarization can be switched in a stunning hysteretic fashion. Because the magnetic order in CDC is mediated by large organic molecules, our study shows that magnetoelectric interactions can exist in this important class of materials, opening the road to designing magnetoelectrics and multiferroics using large molecules as building blocks. Further, we demonstrate that CDC undergoes a magnetoelectric quantum phase transition -the first of its kind, where both ferroelectric and magnetic order emerge simultaneously as a function of magnetic field at very low temperatures.

  2. Preparation of nanocrystalline metal oxides and intermetallic phases by controlled thermolysis of organometallic coordination polymers

    NASA Astrophysics Data System (ADS)

    Rehbein, Marcus; Epple, Matthias; Fischer, R. Dieter

    2000-06-01

    Organometallic coordination polymers of the super-Prussian blue type [(Me 3Sn) nM(CN) 6] (Me=CH 3; n=3, 4; M=Fe, Co, Ru) were subjected to thermolysis in different atmospheres (air, argon, hydrogen/nitrogen). In air, oxides were found: Fe 2O 3/SnO 2 (crystalline and nanocrystalline), Co 2SnO 4 and RuO 2. In argon and in hydrogen, the intermetallic phases FeSn 2, CoSn 2, Ru 3Sn 7 and Fe 3SnC were obtained. A detailed mechanistic study was carried out using thermogravimetry (TG), X-ray diffraction (XRD), X-ray absorption spectroscopy (EXAFS) at Fe, Co, Ru and Sn K-edges, infrared spectroscopy (IR) and elemental analysis. Below 250°C, Me 3SnCN and (CN) 2 are released, whereas above 250°C oxidation or pyrolysis leads to the corresponding oxides or intermetallic phases. Polymeric cyanides containing at least two metals have turned out to be suitable precursors to prepare well-defined oxides and intermetallic phases at comparatively low temperature.

  3. Electron spin resonance study of GaAs:Er,O grown by organometallic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Yoshida, Makoto; Hiraka, Kensaku; Ohta, Hitoshi; Fujiwara, Yasufumi; Koizumi, Atsushi; Takeda, Yoshikazu

    2004-10-01

    Electron spin resonance (ESR) measurements of GaAs:Er,O grown by organometallic vapor phase epitaxy have been performed at 9.49GHz from 4.5to13K. Several anisotropic ESR signals (A, B, C, and D) are observed, which is consistent with the previous reports. We reexamined the angular dependence and temperature dependence of the signals in detail. Our ESR results indicate that the direction of alignment of two oxygen atoms or two arsenic atoms for an Er-2O center deviates from the ⟨110⟩ direction in various ways, resulting in the various Er-2O centers. Our ESR results also indicate that the paramagnetic states of the Er centers in GaAs change to a singletlike nonmagnetic state below 8K. The ESR measurements under illumination have been performed to investigate the effect of photoexcitation of the host. This result indicates that the energy transfer efficiency from the host to the B center is especially large. We found that the luminescent Er-2O center B and another Er-2O center C considerably differ in the coupling with the lattice.

  4. p-type Mesoscopic Nickel Oxide/Organometallic Perovskite Heterojunction Solar Cells

    PubMed Central

    Wang, Kuo-Chin; Jeng, Jun-Yuan; Shen, Po-Shen; Chang, Yu-Cheng; Diau, Eric Wei-Guang; Tsai, Cheng-Hung; Chao, Tzu-Yang; Hsu, Hsu-Cheng; Lin, Pei-Ying; Chen, Peter; Guo, Tzung-Fang; Wen, Ten-Chin

    2014-01-01

    In this article, we present a new paradigm for organometallic hybrid perovskite solar cell using NiO inorganic metal oxide nanocrystalline as p-type electrode material and realized the first mesoscopic NiO/perovskite/[6,6]-phenyl C61-butyric acid methyl ester (PC61BM) heterojunction photovoltaic device. The photo-induced transient absorption spectroscopy results verified that the architecture is an effective p-type sensitized junction, which is the first inorganic p-type, metal oxide contact material for perovskite-based solar cell. Power conversion efficiency of 9.51% was achieved under AM 1.5 G illumination, which significantly surpassed the reported conventional p-type dye-sensitized solar cells. The replacement of the organic hole transport materials by a p-type metal oxide has the advantages to provide robust device architecture for further development of all-inorganic perovskite-based thin-film solar cells and tandem photovoltaics. PMID:24755642

  5. Organometallic halide perovskite/barium di-silicide thin-film double-junction solar cells

    NASA Astrophysics Data System (ADS)

    Vismara, R.; Isabella, O.; Zeman, M.

    2016-04-01

    Barium di-silicide (BaSi2) is an abundant and inexpensive semiconductor with appealing opto-electrical properties. In this work we show that a 2-μm thick BaSi2-based thin-film solar cell can exhibit an implied photo-current density equal to 41.1 mA/cm2, which is higher than that of a state-of-the-art wafer-based c-Si hetero-junction solar cell. This performance makes BaSi2 an attractive absorber for high-performing thin-film and multi-junction solar cells. In particular, to assess the potential of barium di-silicide, we propose a thin-film double-junction solar cell based on organometallic halide perovskite (CH3NH3PbI3) as top absorber and BaSi2 as bottom absorber. The resulting modelled ultra-thin double-junction CH3NH3PbI3 / BaSi2 (< 2 μm) exhibits an implied total photo-current density equal to 38.65 mA/cm2 (19.84 mA/cm2 top cell, 18.81 mA/cm2 bottom cell) and conversion efficiencies up to 28%.

  6. Influence of PPh₃ moiety in the anticancer activity of new organometallic ruthenium complexes.

    PubMed

    Sáez, Rubén; Lorenzo, Julia; Prieto, Ma Jose; Font-Bardia, Mercè; Calvet, Teresa; Omeñaca, Nuria; Vilaseca, Marta; Moreno, Virtudes

    2014-07-01

    The effect of the PPh3 group in the antitumor activity of some new organometallic ruthenium(II) complexes has been investigated. Several complexes of the type [Ru((II))(Cl)(PPh3)(Lig-N)], [Ru((II))(Cl)2(Lig-N)] (where Lig-N=pyridine derivate) and [Ru((II))(Cl)(PPh3)2], have been synthesized and characterized. A noticeable increment of the antitumor activity and cytotoxicity of the complexes due to the presence of PPh3 moiety has also been demonstrated, affording IC50 values of 5.2 μM in HL-60 tumor cell lines. Atomic force microscopy, circular dichroism and electrophoresis experiments have proved that these complexes can bind DNA resulting in a distortion of both secondary and tertiary structures. Ethidium bromide displacement fluorescence spectroscopy studies and viscosity measurements support that the presence of PPh3 group induces intercalation interactions with DNA. Indeed, crystallographic analysis, suggest that intra-molecular π-π interactions could be involved in the intercalation within DNA base pairs. Furthermore, high performance liquid chromatography mass spectrometry (HPLC-MS) studies have confirmed a strong interaction between ruthenium complexes and proteins (ubiquitin and potato carboxypeptidase inhibitor - PCI) including slower kinetics due to the presence of PPh3 moiety, which could have an important role in detoxification mechanism and others. Finally, ion mobility mass spectrometry (IMMS) experiments have proved that there is no significant change in the gas phase structural conformation of the proteins owing to their bonding to ruthenium complexes.

  7. Organometallic ruthenium anticancer complexes inhibit human glutathione-S-transferase π.

    PubMed

    Lin, Yu; Huang, Yongdong; Zheng, Wei; Wang, Fuyi; Habtemariam, Abraha; Luo, Qun; Li, Xianchan; Wu, Kui; Sadler, Peter J; Xiong, Shaoxiang

    2013-11-01

    The organometallic ruthenium(II) anticancer complexes [(η(6)-arene)Ru(en)Cl](+) (arene = p-cymene (1), biphenyl (2) or 9,10-dihydrophenanthrene (3); en = ethylenediamine), exhibit in vitro and in vivo anticancer activities. In the present work, we show that they inhibit human glutathione-S-transferase π (GSTπ) with IC50 values of 59.4 ± 1.3, 63.2 ± 0.4 and 37.2 ± 1.1 μM, respectively. Mass spectrometry revealed that complex 1 binds to the S-donors of Cys15, Cys48 within the G-site and Cys102 at the interface of the GSTπ dimer, while complex 2 binds to Cys48 and Met92 at the dimer interface and complex 3 to Cys15, Cys48 and Met92. Moreover, the binding of complex 1 to Cys15 and Cys102, complex 2 to Cys48 and complex 3 to Cys15 induces the irreversible oxidation of the coordinated thiolates to sulfenates. Molecular modeling studies indicate that the coordination of the {(arene)Ru(en)}(2+) fragment to Cys48 blocks the hydrophilic G-site sterically, perhaps preventing substrate from proper positioning and accounting for the reduction in enzymatic activity of ruthenated GSTπ. The binding of the ruthenium arene complexes to Cys102 or Met92 disrupts the dimer interface which is an essential structural feature for the proper functioning of GSTπ, perhaps also contributing to the inhibition of GSTπ.

  8. Time resolved infrared studies of C-H bond activation by organometallics

    SciTech Connect

    Asplund, M.C. |

    1998-06-01

    This work describes how step-scan Fourier Transform Infrared spectroscopy and visible and near infrared ultrafast lasers have been applied to the study of the photochemical activation of C-H bonds in organometallic systems, which allow for the selective breaking of C-H bonds in alkanes. The author has established the photochemical mechanism of C-H activation by Tp{sup *}Rh(CO){sub 2}(Tp{sup *} = HB-Pz{sup *}{sub 3}, Pz = 3,5-dimethylpyrazolyl) in alkane solution. The initially formed monocarbonyl forms a weak solvent complex, which undergoes a change in Tp{sup *} ligand connectivity. The final C-H bond breaking step occurs at different time scales depending on the structure of the alkane. In linear solvents, the time scale is <50 ns and cyclic alkanes is {approximately}200 ps. The reactivity of the Tp{sup *}Rh(CO){sub 2} system has also been studied in aromatic solvents. Here the reaction proceeds through two different pathways, with very different time scales. The first proceeds in a manner analogous to alkanes and takes <50 ns. The second proceeds through a Rh-C-C complex, and takes place on a time scale of 1.8 {micro}s.

  9. Formation of Organometallic Intermediate States in On-Surface Ullmann Couplings.

    PubMed

    Barton, Dennis; Gao, Hong-Ying; Held, Philipp Alexander; Studer, Armido; Fuchs, Harald; Doltsinis, Nikos L; Neugebauer, Johannes

    2017-02-17

    Possible origins of the formation of organometallic intermediates in on-surface Ullmann couplings have been investigated by surface tunneling microscopy (STM) and density functional theory (DFT) calculations. We consider the case of iodobenzenes on the coinage metals Au, Ag and Cu. We found experimental evidence for the formation of surface vacancies and the presence of metal adatoms in these coupling reactions, which are taken as a hint for the reactive extraction of surface atoms by adsorbates. In a second step, we demonstrate by ab initio molecular dynamics calculations for aryl-iodides on copper that metal atoms can be pulled out of the surface to form metalorganic species. By contrast, a thermally activated provision of a metal atom from the surface to form an adatom is energetically unfavourable. Finally, we investigate the mechanism and energetics of the reactive extraction of surface metal atoms by means of (climbing-image) nudged-elastic-band density-functional theory calculations for iodobenzene on copper, silver and gold, and analyze our results in the light of the experimental findings.

  10. Study of surface relief gratings on azo organometallic films in picosecond regime.

    PubMed

    Luc, J; Bouchouit, K; Czaplicki, R; Fillaut, J-L; Sahraoui, B

    2008-09-29

    Materials for optical data storage and optical information processing must exhibit good holographic properties. Many materials for these applications have been already proposed. Here we describe a grating inscription process characterized by short inscription time and long-time stability. A series of ruthenium-acetylide organometallic complexes containing an azobenzene fragment were synthesized. Photo-induced gratings were produced by short pulse (16 ps, 532 nm) laser irradiation. The surface relief gratings formed at the same time were observed by atomic force microscope. In this work, we highlight the short inscription times brought into play as well as the good temporal stability of these gratings stored at room temperature. We study the influence of the polarization states and the light intensity of writing beams on the dynamics of the surface relief gratings formation and we compare these results with those of a known representative of azobenzene derivative (Disperse Red 1). Lastly, we show that it is possible to write two-dimensional surface relief gratings.

  11. Electronic and magnetic properties of silicon supported organometallic molecular wires: a density functional theory (DFT) study.

    PubMed

    Liu, Xia; Tan, Yingzi; Li, Xiuling; Wu, Xiaojun; Pei, Yong

    2015-08-28

    The electronic and magnetic properties of transition metal (TM = Sc, Ti, V, Cr and Mn) atom incorporated single and double one-dimensional (1D) styrene molecular wires confined on the hydrogen-terminated Si(100) surface are explored for the first time by means of spin-polarized density functional theory, denoted as Si-[TM(styrene)]. It is unveiled that TM atoms bind asymmetrically to the adjacent phenyl rings, which leads to novel electronic and magnetic properties in stark contrast to the well-studied gas phase TM-benzene molecular wires. Si-[Mn(styrene)]∞ and Si-[Cr(styrene)]∞ single molecular wires (SMWs) are a ferromagnetic semiconductor and half metal, respectively. Creation of H-atom defects on the silicon surface can introduce an impurity metallic band, which leads to novel half-metallic magnetism of a Si-[Mn(styrene)]∞ system. Moreover, double molecular wires (DMWs) containing two identical or hetero SMWs are theoretically designed. The [Mn(styrene)]∞-[Cr(styrene)]∞ DMW exhibits half-metallic magnetism where the spin-up and spin-down channels are contributed by two single molecular wires. Finally, we demonstrate that introducing a TM-defect may significantly affect the electronic structure and magnetic properties of molecular wires. These studies provide new insights into the structure and properties of surface supported 1-D sandwiched molecular wires and may inspire the future experimental synthesis of substrate confined organometallic sandwiched molecular wires.

  12. Nanometre-sized GaAs wires grown by organo-metallic vapour-phase epitaxy

    NASA Astrophysics Data System (ADS)

    Hiruma, Kenji; Haraguchi, Keiichi; Yazawa, Masamitsu; Madokoro, Yuuichi; Katsuyama, Toshio

    2006-06-01

    We grew GaAs wires as thin as 20 nm on a GaAs(111)B substrate using organo-metallic vapour-phase epitaxy (OMVPE), with Au as a growth catalyst. To investigate the growth characteristics, we compared two methods of depositing Au. In the first, Au was deposited by vacuum evaporation, and the deposition thickness was varied to form a planar Au layer. We found that an Au layer thickness of 1 nm was best for forming cylindrical shaped wires. Next, a new method of injecting Au onto an area of a few micrometres was tested using a focused ion beam (FIB), and this method was found to be effective for growing wires as thin as 30-80 nm. However, the wire width did not depend on the injected density of Au. We based our analysis of the results on an ion implantation model. GaAs wires with a p-n junction along the \\langle 111\\rangle \\mathrm {B} direction were formed by changing dopants from silicon to carbon during growth. We observed an optical emission with a peak intensity at the wavelength of 910-920 nm during continuous current injection into the wires at 300 K. A spectral blue-shift in the light emission and a polarization along the wire growth direction were also revealed at 77 K.

  13. Low-Temperature Wet Conformal Nickel Silicide Deposition for Transistor Technology through an Organometallic Approach.

    PubMed

    Lin, Tsung-Han; Margossian, Tigran; De Marchi, Michele; Thammasack, Maxime; Zemlyanov, Dmitry; Kumar, Sudhir; Jagielski, Jakub; Zheng, Li-Qing; Shih, Chih-Jen; Zenobi, Renato; De Micheli, Giovanni; Baudouin, David; Gaillardon, Pierre-Emmanuel; Copéret, Christophe

    2017-02-08

    The race for performance of integrated circuits is nowadays facing a downscale limitation. To overpass this nanoscale limit, modern transistors with complex geometries have flourished, allowing higher performance and energy efficiency. Accompanying this breakthrough, challenges toward high-performance devices have emerged on each significant step, such as the inhomogeneous coverage issue and thermal-induced short circuit issue of metal silicide formation. In this respect, we developed a two-step organometallic approach for nickel silicide formation under near-ambient temperature. Transmission electron and atomic force microscopy show the formation of a homogeneous and conformal layer of NiSix on pristine silicon surface. Post-treatment decreases the carbon content to a level similar to what is found for the original wafer (∼6%). X-ray photoelectron spectroscopy also reveals an increasing ratio of Si content in the layer after annealing, which is shown to be NiSi2 according to X-ray absorption spectroscopy investigation on a Si nanoparticle model. I-V characteristic fitting reveals that this NiSi2 layer exhibits a competitive Schottky barrier height of 0.41 eV and series resistance of 8.5 Ω, thus opening an alternative low-temperature route for metal silicide formation on advanced devices.

  14. Hydrodeoxygenation of prairie cordgrass bio-oil over Ni based activated carbon synergistic catalysts combined with different metals.

    PubMed

    Cheng, Shouyun; Wei, Lin; Zhao, Xianhui; Kadis, Ethan; Cao, Yuhe; Julson, James; Gu, Zhengrong

    2016-06-25

    Bio-oil can be upgraded through hydrodeoxygenation (HDO). Low-cost and effective catalysts are crucial for the HDO process. In this study, four inexpensive combinations of Ni based activated carbon synergistic catalysts including Ni/AC, Ni-Fe/AC, Ni-Mo/AC and Ni-Cu/AC were evaluated for HDO of prairie cordgrass (PCG) bio-oil. The tests were carried out in the autoclave under mild operating conditions with 500psig of H2 pressure and 350°C temperature. The catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and transmission electron microscope (TEM). The results show that all synergistic catalysts had significant improvements on the physicochemical properties (water content, pH, oxygen content, higher heating value and chemical compositions) of the upgraded PCG bio-oil. The higher heating value of the upgraded bio-oil (ranging from 29.65MJ/kg to 31.61MJ/kg) improved significantly in comparison with the raw bio-oil (11.33MJ/kg), while the oxygen content reduced to only 21.70-25.88% from 68.81% of the raw bio-oil. Compared to raw bio-oil (8.78% hydrocarbons and no alkyl-phenols), the Ni/AC catalysts produced the highest content of gasoline range hydrocarbons (C6-C12) at 32.63% in the upgraded bio-oil, while Ni-Mo/AC generated the upgraded bio-oil with the highest content of gasoline blending alkyl-phenols at 38.41%.

  15. Effects of alloying element and temperature on the stacking fault energies of dilute Ni-base superalloys.

    PubMed

    Shang, S L; Zacherl, C L; Fang, H Z; Wang, Y; Du, Y; Liu, Z K

    2012-12-19

    A systematic study of stacking fault energy (γ(SF)) resulting from induced alias shear deformation has been performed by means of first-principles calculations for dilute Ni-base superalloys (Ni(23)X and Ni(71)X) for various alloying elements (X) as a function of temperature. Twenty-six alloying elements are considered, i.e., Al, Co, Cr, Cu, Fe, Hf, Ir, Mn, Mo, Nb, Os, Pd, Pt, Re, Rh, Ru, Sc, Si, Ta, Tc, Ti, V, W, Y, Zn, and Zr. The temperature dependence of γ(SF) is computed using the proposed quasistatic approach based on a predicted γ(SF)-volume-temperature relationship. Besides γ(SF), equilibrium volume and the normalized stacking fault energy (Γ(SF) = γ(SF)/Gb, with G the shear modulus and b the Burgers vector) are also studied as a function of temperature for the 26 alloying elements. The following conclusions are obtained: all alloying elements X studied herein decrease the γ(SF) of fcc Ni, approximately the further the alloying element X is from Ni on the periodic table, the larger the decrease of γ(SF) for the dilute Ni-X alloy, and roughly the γ(SF) of Ni-X decreases with increasing equilibrium volume. In addition, the values of γ(SF) for all Ni-X systems decrease with increasing temperature (except for Ni-Cr at higher Cr content), and the largest decrease is observed for pure Ni. Similar to the case of the shear modulus, the variation of γ(SF) for Ni-X systems due to various alloying elements is traceable from the distribution of (magnetization) charge density: the spherical distribution of charge density around a Ni atom, especially a smaller sphere, results in a lower value of γ(SF) due to the facility of redistribution of charges. Computed stacking fault energies and the related properties are in favorable accord with available experimental and theoretical data.

  16. Solidification and welding metallurgy of experimental Ni-base and Fe-base superalloys containing Nb, Si and C

    NASA Astrophysics Data System (ADS)

    Dupont, John Neuman

    1997-12-01

    The solidification and weldability of experimental Ni base and Fe base superalloys containing Nb, Si, and C was studied using a combination of differential thermal analysis, quenching experiments, varestraint testing, and microstructural characterization techniques. The solidification reaction sequences responsible for microstructural development were found to be similar to those expected in the Ni-Nb-C ternary system. The solute rich interdendritic liquid exhibited two eutectic-type reactions at the terminal stages of solidification: L->(gamma + NbC) and L->(gamma + Laves). A pseudo ternary gamma-Nb-C approach, modelled after the simple Ni-Nb-C system, was developed to provide a quantitative description of solidification behavior for these experimental alloys. Solute redistribution calculations in the model are based on a previous approach developed by Mehrabian and Flemings, with modifications made to account for the high diffusion rate of C in the solid. Solidification parameters for Nb and C were determined through DTA and electron probe microanalysis techniques and used as inputs to the model. Reasonable agreement is found between calculated volume fractions of the gamma/NbC and gamma/Laves constituents and those measured experimentally. The modelling results permit detailed descriptions of the relation between alloy composition and microstructural evolution during solidification. The results are also joined with experimental observations of fusion zone microstructures to determine the relation between alloy composition and solidification cracking susceptibility. A method is proposed for calculating the distribution of liquid in the solid + liquid zone as an aid to determining the individual effects of alloy composition on solidification cracking susceptibility.

  17. Thin Co/Ni-based bottom pinned spin-transfer torque magnetic random access memory stacks with high annealing tolerance

    SciTech Connect

    Tomczak, Y.; Swerts, J.; Mertens, S.; Lin, T.; Couet, S.; Sankaran, K.; Pourtois, G.; Kim, W.; Souriau, L.; Van Elshocht, S.; Kar, G.; Furnemont, A.; Liu, E.

    2016-01-25

    Spin-transfer torque magnetic random access memory (STT-MRAM) is considered as a replacement for next generation embedded and stand-alone memory applications. One of the main challenges in the STT-MRAM stack development is the compatibility of the stack with CMOS process flows in which thermal budgets up to 400 °C are applied. In this letter, we report on a perpendicularly magnetized MgO-based tunnel junction (p-MTJ) on a thin Co/Ni perpendicular synthetic antiferromagnetic layer with high annealing tolerance. Tunnel magneto resistance (TMR) loss after annealing occurs when the reference layer loses its perpendicular magnetic anisotropy due to reduction of the CoFeB/MgO interfacial anisotropy. A stable Co/Ni based p-MTJ stack with TMR values of 130% at resistance-area products of 9 Ω μm{sup 2} after 400 °C anneal is achieved via moment control of the Co/Ta/CoFeB reference layer. Thinning of the CoFeB polarizing layer down to 0.8 nm is the key enabler to achieve 400 °C compatibility with limited TMR loss. Thinning the Co below 0.6 nm leads to a loss of the antiferromagnetic interlayer exchange coupling strength through Ru. Insight into the thickness and moment engineering of the reference layer is displayed to obtain the best magnetic properties and high thermal stability for thin Co/Ni SAF-based STT-MRAM stacks.

  18. Environmental Effects in Niobium Base Alloys and Other Selected Intermetallic Compounds

    DTIC Science & Technology

    1988-12-15

    Niobium aluminides and silicides as well as other intermetallic corn unds have potential for use in advanced gas turbines where increased operating...diffusion aluminide coatings on Ni-base alloys(10), Fe- silicides (l 1), and Ni- ’ silicides (12) indicate similar behavior to that in Figure 8. Typical... Niobium W MAR- 2 7 1983 Base Alloys and Other Selected Intermetallic Compounds &Simukx Defense Advanced Research Projects Agency . DARPA Order No. 6155

  19. Aldehydes as alkyl carbanion equivalents for additions to carbonyl compounds

    NASA Astrophysics Data System (ADS)

    Wang, Haining; Dai, Xi-Jie; Li, Chao-Jun

    2016-12-01

    Nucleophilic addition reactions of organometallic reagents to carbonyl compounds for carbon-carbon bond construction have played a pivotal role in modern chemistry. However, this reaction's reliance on petroleum-derived chemical feedstocks and a stoichiometric quantity of metal have prompted the development of many carbanion equivalents and catalytic metal alternatives. Here, we show that naturally occurring carbonyls can be used as latent alkyl carbanion equivalents for additions to carbonyl compounds, via reductive polarity reversal. Such 'umpolung' reactivity is facilitated by a ruthenium catalyst and diphosphine ligand under mild conditions, delivering synthetically valuable secondary and tertiary alcohols in up to 98% yield. The unique chemoselectivity exhibited by carbonyl-derived carbanion equivalents is demonstrated by their tolerance to protic reaction media and good functional group compatibility. Enantioenriched tertiary alcohols can also be accessed with the aid of chiral ligands, albeit with moderate stereocontrol. Such carbonyl-derived carbanion equivalents are anticipated to find broad utility in chemical bond formation.

  20. (N-pyrrolyl)B(C6F5)2--a new organometallic Lewis acid for the generation of group 4 metallocene cation complexes.

    PubMed

    Kehr, G; Fröhlich, R; Wibbeling, B; Erker, G

    2000-01-01

    Treatment of the (C6F5)2BF x OEt2 (3) complex with N-pyrrolyl lithium gives bis(pentafluorophenyl)(N-pyrrolyl)borane (2), a strong organometallic Lewis acid, which was characterized by X-ray diffraction (B-N bond length: 1.401(5) A). It exhibits a columnar superstructure in the crystal and contains pi-stacks of pyrrolyl units. Compound 2 readily abstracts alkyl anions from a variety of alkyl Group 4 metallocene-type complexes and leads to the clean formation of the respective metallocene ions or ion pairs. For example, the treatment of Cp3ZrCH3 (9) with 2 transfers a methyl anion to yield the ion pair [Cp3Zr]+[(C4H4N)B(CH3)(C6F5)2]- (12). The X-ray crystal structure analysis of 12 shows a close contact between zirconium and the pyrrolyl-beta-carbon (2.641(2) A). The borane 2 adds to (butadiene)zirconocene (13) to yield the betaine system [Cp2Zr]+[(C4H6)B- (NC4H4)(C6F)2]- (15). Complex 15 contains a distorted eta3-allyl moiety inside the metallacyclic framework and it features an internal Zr+...(pyrrolyl)B- ion pair interaction with a Zr...pyrrolyl-alphacarbon separation of 2.723(3) A (determined by X-ray diffraction). From the dynamic NMR spectra of 15 the bond strength of the internal ion pair interaction was estimated to be deltaGdiss (223 K) approximately = to15 kcalmol(-1). Treatment of dimethylzirconocene (16) with 2 yields the metallocene borate salt [Cp2ZrCH3]+[(C4H4N)B(CH3)(C6F5)2]- (17), which is an active catalyst for the polymerization of ethene.

  1. Structural studies of crystals of organic and organoelement compounds using modern quantum chemical calculations within the framework of the density functional theory

    NASA Astrophysics Data System (ADS)

    Korlyukov, Alexander A.; Antipin, Mikhail Yu

    2012-02-01

    The review generalizes the results of structural studies of crystals of organic and organometallic compounds by modern quantum chemical calculations within the framework of the density functional theory reported in the last decade. Features of the software for such calculations are discussed. Examples of the use of quantum chemical calculations for the studies of the electronic structure, spectroscopic and other physicochemical properties of molecular crystals are presented. The bibliography includes 223 references.

  2. Single source precursors for the OMCVD of 3/5 compound semiconductors

    NASA Astrophysics Data System (ADS)

    Jones, Richard A.; Ekerdt, John G.

    1993-07-01

    The overall goals are to develop the fundamental chemistry of group III and group V compounds in several key areas. The underlying rationale is to ultimately improve on the preparation and properties of important materials used in the semiconductor industries. The research comprises a collaboration between a synthetic inorganic chemist and a chemical engineer. The three main areas are single source precursors for OMCVD of III/V semiconductors; alternative precursors for OMCVD studies, group III or V hydrides; and the organometallic chemistry of bismuth. The first area will employ compounds of the general type (R2M(mu-R'2E))2 (M = Al, Ga, In; E = P, As; R, R' = alkyl, aryl, etc.) and the second will employ similar compounds but with R or R' replaced by the hydride ligand. The paper explores the relationships between precursor structures, mechanisms of decomposition and thin film formation, and the morphological and electrical properties of the grown films. In the third area the document explores the organometallic chemistry of bismuth and compounds which may serve as precursors to important materials such as InBiSb.

  3. Volatile organometallic complexes suitable for use in chemical vapor depositions on metal oxide films

    DOEpatents

    Giolando, Dean M.

    2003-09-30

    Novel ligated compounds of tin, titanium, and zinc are useful as metal oxide CVD precursor compounds without the detriments of extreme reactivity yet maintaining the ability to produce high quality metal oxide coating by contact with heated substrates.

  4. Mechanistic Studies at the Interface Between Organometallic Chemistry and Homogeneous Catalysis

    SciTech Connect

    Casey, Charles P

    2012-11-14

    Mechanistic Studies at the Interface Between Organometallic Chemistry and Homogeneous Catalysis Charles P. Casey, Principal Investigator Department of Chemistry, University of Wisconsin - Madison, Madison, Wisconsin 53706 Phone 608-262-0584 FAX: 608-262-7144 Email: casey@chem.wisc.edu http://www.chem.wisc.edu/main/people/faculty/casey.html Executive Summary. Our goal was to learn the intimate mechanistic details of reactions involved in homogeneous catalysis and to use the insight we gain to develop new and improved catalysts. Our work centered on the hydrogenation of polar functional groups such as aldehydes and ketones and on hydroformylation. Specifically, we concentrated on catalysts capable of simultaneously transferring hydride from a metal center and a proton from an acidic oxygen or nitrogen center to an aldehyde or ketone. An economical iron based catalyst was developed and patented. Better understanding of fundamental organometallic reactions and catalytic processes enabled design of energy and material efficient chemical processes. Our work contributed to the development of catalysts for the selective and mild hydrogenation of ketones and aldehydes; this will provide a modern green alternative to reductions by LiAlH4 and NaBH4, which require extensive work-up procedures and produce waste streams. (C5R4OH)Ru(CO)2H Hydrogenation Catalysts. Youval Shvo described a remarkable catalytic system in which the key intermediate (C5R4OH)Ru(CO)2H (1) has an electronically coupled acidic OH unit and a hydridic RuH unit. Our efforts centered on understanding and improving upon this important catalyst for reduction of aldehydes and ketones. Our mechanistic studies established that the reduction of aldehydes by 1 to produce alcohols and a diruthenium bridging hydride species occurs much more rapidly than regeneration of the ruthenium hydride from the diruthenium bridging hydride species. Our mechanistic studies require simultaneous transfer of hydride from ruthenium to

  5. Electronic and magnetic properties of silicon supported organometallic molecular wires: a density functional theory (DFT) study

    NASA Astrophysics Data System (ADS)

    Liu, Xia; Tan, Yingzi; Li, Xiuling; Wu, Xiaojun; Pei, Yong

    2015-08-01

    The electronic and magnetic properties of transition metal (TM = Sc, Ti, V, Cr and Mn) atom incorporated single and double one-dimensional (1D) styrene molecular wires confined on the hydrogen-terminated Si(100) surface are explored for the first time by means of spin-polarized density functional theory, denoted as Si-[TM(styrene)]. It is unveiled that TM atoms bind asymmetrically to the adjacent phenyl rings, which leads to novel electronic and magnetic properties in stark contrast to the well-studied gas phase TM-benzene molecular wires. Si-[Mn(styrene)]∞ and Si-[Cr(styrene)]∞ single molecular wires (SMWs) are a ferromagnetic semiconductor and half metal, respectively. Creation of H-atom defects on the silicon surface can introduce an impurity metallic band, which leads to novel half-metallic magnetism of a Si-[Mn(styrene)]∞ system. Moreover, double molecular wires (DMWs) containing two identical or hetero SMWs are theoretically designed. The [Mn(styrene)]∞-[Cr(styrene)]∞ DMW exhibits half-metallic magnetism where the spin-up and spin-down channels are contributed by two single molecular wires. Finally, we demonstrate that introducing a TM-defect may significantly affect the electronic structure and magnetic properties of molecular wires. These studies provide new insights into the structure and properties of surface supported 1-D sandwiched molecular wires and may inspire the future experimental synthesis of substrate confined organometallic sandwiched molecular wires.The electronic and magnetic properties of transition metal (TM = Sc, Ti, V, Cr and Mn) atom incorporated single and double one-dimensional (1D) styrene molecular wires confined on the hydrogen-terminated Si(100) surface are explored for the first time by means of spin-polarized density functional theory, denoted as Si-[TM(styrene)]. It is unveiled that TM atoms bind asymmetrically to the adjacent phenyl rings, which leads to novel electronic and magnetic properties in stark contrast to

  6. Organometallic chemical vapor deposition of silicon nitride films enhanced by atomic nitrogen generated from surface-wave plasma

    SciTech Connect

    Okada, H.; Kato, M.; Ishimaru, T.; Sekiguchi, H.; Wakahara, A.; Furukawa, M.

    2014-02-20

    Organometallic chemical vapor deposition of silicon nitride films enhanced by atomic nitrogen generated from surface-wave plasma is investigated. Feasibility of precursors of triethylsilane (TES) and bis(dimethylamino)dimethylsilane (BDMADMS) is discussed based on a calculation of bond energies by computer simulation. Refractive indices of 1.81 and 1.71 are obtained for deposited films with TES and BDMADMS, respectively. X-ray photoelectron spectroscopy (XPS) analysis of the deposited film revealed that TES-based film coincides with the stoichiometric thermal silicon nitride.

  7. Structure-activity relationships for organometallic osmium arene phenylazopyridine complexes with potent anticancer activity.

    PubMed

    Fu, Ying; Habtemariam, Abraha; Basri, Aida M B H; Braddick, Darren; Clarkson, Guy J; Sadler, Peter J

    2011-10-28

    We report the synthesis and characterisation of 32 half sandwich phenylazopyridine Os(II) arene complexes [Os(η(6)-arene)(phenylazopyridine)X](+) in which X is chloride or iodide, the arene is p-cymene or biphenyl and the pyridine and phenyl rings contain a variety of substituents (F, Cl, Br, I, CF(3), OH or NO(2)). Ten X-ray crystal structures have been determined. Cytotoxicity towards A2780 human ovarian cancer cells ranges from high potency at nanomolar concentrations to inactivity. In general the introduction of an electron-withdrawing group (e.g. F, Cl, Br or I) at specific positions on the pyridine ring significantly increases cytotoxic activity and aqueous solubility. Changing the arene from p-cymene to biphenyl and the monodentate ligand X from chloride to iodide also increases the activity significantly. Activation by hydrolysis and DNA binding appears not to be the major mechanism of action since both the highly active complex [Os(η(6)-bip)(2-F-azpy)I]PF(6) (9) and the moderately active complex [Os(η(6)-bip)(3-Cl-azpy)I]PF(6) (23) are very stable and inert towards aquation. Studies of octanol-water partition coefficients (log P) and subcellular distributions of osmium in A2780 human ovarian cancer cells suggested that cell uptake and targeting to cellular organelles play important roles in determining activity. Although complex 9 induced the production of reactive oxygen species (ROS) in A2780 cells, the ROS level did not appear to play a role in the mechanism of anticancer activity. This class of organometallic osmium complexes has new and unusual features worthy of further exploration for the design of novel anticancer drugs.

  8. Shadow masked organometallic vapor phase epitaxy for advanced micro-optical structures

    NASA Astrophysics Data System (ADS)

    Peake, Gregory Merwin

    2000-12-01

    This thesis presents novel techniques and applications of nonplanar chemical vapor deposition (CVD) for optoelectronic materials and devices. Specifically, nonplanar organometallic vapor phase epitaxy (OMVPE) employing a shadow mask has been developed for the fabrication of integrated optoelectronic structures. Shadow masked OMVPE (SM-OMVPE) is currently the only technique known to produce thick, nonplanar layers of single crystal material without macroscopic faceting. By the use of SM-OMVPE, various microlenses, micromirrors and novel devices have been designed fabricated and tested. Shadow masked microlenses with record short focal lengths have been produced. High quality microlens arrays with accurate control of lens diameter, sagitta, focal length, astigmatism and position have been designed, fabricated and tested. The author has shown that precise three-dimensional control during crystal growth can be employed to construct useful optoelectronic structures in a reproducible manner. This work also presents novel techniques for the fabrication of shadow masks. A high aluminum- concentration spacer layer and chemical recipes for the removal of epitaxial shadow masks are reported. In addition, the first reusable shadow mask constructed by reactive ion etching has been utilized for the growth of shadow masked structures. Direct fusion wafer bonding of silicon shadow masks was first developed by the author and has proven to be a robust, clean and reliable technique for mask placement. The application of shadow masked growth to vertical cavity semiconductor lasers (VCSELs) was initiated in this work. Microlenses were designed for top-emitting VCSELs to provide focusing of the output beam and these designs are currently being fabricated at Sandia National Laboratories. Furthermore, by introducing curvature to the distributed Bragg reflector (DBR) mirrors, a high power single mode VCSEL has been designed. The author has grown the first concentrically

  9. Catalytic ionic hydrogenation of ketones using tungsten or molybdenum organometallic species

    DOEpatents

    Voges, Mark; Bullock, R. Morris

    2000-01-01

    The present invention is a process for the catalytic hydrogenation of ketones and aldehydes to alcohols at low temperatures and pressures using organometallic molybdenum and tungsten complexes. The functional group is selected from groups represented by the formulas R(C.dbd.O)R' and R(C.dbd.O)H, wherein R and R' are selected from hydrogen or any alkyl or aryl group. The active catalyst for the process has the form: [CpM(CO).sub.2 (PR*.sub.3) L].sup.+ A.sup.-, where Cp=.eta..sup.5 -R.sup..tangle-solidup..sub.m C.sub.5 H.sub.5-m and R.sup..tangle-solidup. represents an alkyl group or a halogen (F, Cl, Br, I) or R.sup..tangle-solidup. =OR' (where R'=H, an alkyl group or an aryl group) or R.sup..tangle-solidup. =CO.sub.2 R' (where R'=H, an alkyl group or an aryl group) and m=0 to 5; M represents a molybdenum atom or a tungsten atom; R*.sub.3 represents three hydrocarbon groups selected from a cyclohexyl group (C.sub.6 H.sub.11), a methyl group (CH.sub.3), and a phenyl group (C.sub.6 H.sub.5) and all three R* groups can be the same or different or two of the three groups can be the same; L represents a ligand; and A.sup.- represents an anion. In another embodiment, one, two or three of the R* groups can be an OR*.

  10. Transferrin serves as a mediator to deliver organometallic ruthenium(II) anticancer complexes into cells.

    PubMed

    Guo, Wei; Zheng, Wei; Luo, Qun; Li, Xianchan; Zhao, Yao; Xiong, Shaoxiang; Wang, Fuyi

    2013-05-06

    We report herein a systematic study on interactions of organometallic ruthenium(II) anticancer complex [(η(6)-arene)Ru(en)Cl](+) (arene = p-cymene (1) or biphenyl (2), en = ethylenediamine) with human transferrin (hTf) and the effects of the hTf-ligation on the bioavailability of these complexes with cisplatin as a reference. Incubated with a 5-fold excess of complex 1, 2, or cisplatin, 1 mol of diferric hTf (holo-hTf) attached 0.62 mol of 1, 1.01 mol of 2, or 2.14 mol of cisplatin. Mass spectrometry revealed that both ruthenium complexes coordinated to N-donors His242, His273, His578, and His606, whereas cisplatin bound to O donors Tyr136 and Tyr317 and S-donor Met256 in addition to His273 and His578 on the surface of both apo- and holo-hTf. Moreover, cisplatin could bind to Thr457 within the C-lobe iron binding cleft of apo-hTf. Neither ruthenium nor platinum binding interfered with the recognition of holo-hTf by the transferrin receptor (TfR). The ruthenated/platinated holo-hTf complexes could be internalized via TfR-mediated endocytosis at a similar rate to that of holo-hTf itself. Moreover, the binding to holo-hTf well preserved the bioavailability of the ruthenium complexes, and the hTf-bound 1 and 2 showed a similar cytotoxicity toward the human breast cancer cell line MCF-7 to those of the complexes themselves. However, the conjugation with holo-hTf significantly reduced the cellular uptake of cisplatin and the amount of platinated DNA adducts formed intracellularly, leading to dramatic reduction of cisplatin cytotoxicity toward MCF-7. These findings suggest that hTf can serve as a mediator for the targeting delivery of Ru(arene) anticancer complexes while deactivating cisplatin.

  11. Dual-targeting organometallic ruthenium(II) anticancer complexes bearing EGFR-inhibiting 4-anilinoquinazoline ligands.

    PubMed

    Zhang, Yang; Zheng, Wei; Luo, Qun; Zhao, Yao; Zhang, Erlong; Liu, Suyan; Wang, Fuyi

    2015-08-07

    We have recently demonstrated that complexation with (η(6)-arene)Ru(II) fragments confers 4-anilinoquinazoline pharmacophores a higher potential for inducing cellular apoptosis while preserving the highly inhibitory activity of 4-anilinoquinazolines against EGFR and the reactivity of the ruthenium centre to 9-ethylguanine (Chem. Commun., 2013, 49, 10224-10226). Reported herein are the synthesis, characterisation and evaluation of the biological activity of a new series of ruthenium(ii) complexes of the type [(η(6)-arene)Ru(N,N-L)Cl]PF6 (arene = p-cymene, benzene, 2-phenylethanol or indane, L = 4-anilinoquinazolines). These organometallic ruthenium complexes undergo fast hydrolysis in aqueous solution. Intriguingly, the ligation of (arene)Ru(II) fragments with 4-anilinoquinazolines not only makes the target complexes excellent EGFR inhibitors, but also confers the complexes high affinity to bind to DNA minor grooves while maintaining their reactivity towards DNA bases, characterising them with dual-targeting properties. Molecular modelling studies reveal that the hydrolysis of these complexes is a favourable process which increases the affinity of the target complexes to bind to EGFR and DNA. In vitro biological activity assays show that most of this group of ruthenium complexes are selectively active inhibiting the EGF-stimulated growth of the HeLa cervical cancer cell line, and the most active complex [(η(6)-arene)Ru(N,N-L13)Cl]PF6 (, IC50 = 1.36 μM, = 4-(3'-chloro-4'-fluoroanilino)-6-(2-(2-aminoethyl)aminoethoxy)-7-methoxyquinazoline) is 29-fold more active than its analogue, [(η(6)-arene)Ru(N,N-ethylenediamine)Cl]PF6, and 21-fold more active than gefitinib, a well-known EGFR inhibitor in use clinically. These results highlight the strong promise to develop highly active ruthenium anticancer complexes by ligation of cytotoxic ruthenium pharmacophores with bioactive organic molecules.

  12. Probing the chemistry, electronic structure and redox energetics in pentavalent organometallic actinide complexes

    SciTech Connect

    Graves, Christopher R; Vaughn, Anthony E; Morris, David E; Kiplinger, Jaqueline L

    2008-01-01

    Complexes of the early actinides (Th-Pu) have gained considerable prominence in organometallic chemistry as they have been shown to undergo chemistries not observed with their transition- or lanthanide metal counterparts. Further, while bonding in f-element complexes has historically been considered to be ionic, the issue of covalence remains a subject of debate in the area of actinide science, and studies aimed at elucidating key bonding interactions with 5f-orbitals continue to garner attention. Towards this end, our interests have focused on the role that metal oxidation state plays in the structure, reactivity and spectral properties of organouranium complexes. We report our progress in the synthesis of substituted U{sup V}-imido complexes using various routes: (1) Direct oxidation of U{sup IV}-imido complexes with copper(I) salts; (2) Salt metathesis with U{sup V}-imido halides; (3) Protonolysis and insertion of an U{sup V}-imido alkyl or aryl complex with H-N{double_bond}CPh{sub 2} or N{triple_bond}C-Ph, respectively, to form a U{sup V}-imido ketimide complex. Further, we report and compare the crystallographic, electrochemical, spectroscopic and magnetic characterization of the pentavalent uranium (C{sub 5}Me{sub 5}){sub 2}U({double_bond}N-Ar)(Y) series (Y = OTf, SPh, C{triple_bond}C-Ph, NPh{sub 2}, OPh, N{double_bond}CPh{sub 2}) to further interrogate the molecular, electronic, and magnetic structures of this new class of uranium complexes.

  13. Design of Ni-base superalloys and MCrAlY coatings from first-principles and computational thermodynamics

    NASA Astrophysics Data System (ADS)

    Liu, Xuan

    This thesis explores the thermodynamics of Ni-base superalloys and metallic coatings used in the protection of these alloys. First, a thermodynamic description of the Nb-Re binary system is developed by means of the CALculation of PHAse Diagrams (CALPHAD) method supplemented by first-principles calculations based on density functional theory (DFT) and experimental data in the literature. In addition to terminal solution phases in the Nb-Re system, there are two intermetallic phases, sigma (sigma) and chi (chi), all modeled with sublattice models. Special quasi-random structures (SQS) are employed to mimic the random mixing of the bcc, hcp, and fcc solid solution phases from first-principles. Finite temperature thermodynamic properties of end-members and dilute mixing in each sublattice of the complex sigma and chi phases are predicted from first-principles calculations and the Debye-Gruneisen model. The utility of the Debye-Gruneisen model is then investigated with respect to its fitting parameter known as the scaling factor, and it is found that the prediction of finite-temperature properties can be improved by modification of this factor. This scaling factor is studied using bcc, fcc, hcp systems and the Mg-Zn binary system due to the abundance of thermodynamic data. Predicted Debye temperatures (thetaD), using a calculated scaling factor, show good agreement with experiments and improvements over the scaling factor derived by Moruzzi et al. Finite-temperature thermodynamic properties of intermetallics are investigated to show the efficiency and improved accuracy of the calculated scaling factor. However, for the intermetallic Mg2Zn11, the Debye-Gruneisen model cannot account for anomalous lattice dynamics at low temperatures. The calculated scaling factor is then used throughout the present work for finite-temperature predictions. Another missing piece of the literature includes the thermodynamics of Al-Co-Cr-Ni bond coat system used in the protection of

  14. Corrosion behavior and inhibitive effects on organotin compounds on nickel in formic acid

    SciTech Connect

    Singh, R.N.; Singh, V.B. . Dept. of Chemistry)

    1993-07-01

    Corrosion behavior of nickel (Ni) in different compositions of formic acid (HCOOH) at 30C was studied using the potentiostatic polarization method. The shape of the polarization curve was evaluated, and the corrosion current density, critical current density, and passive current density were determined. HCOOH solution of different composition were aggressive for the anodic dissolution of Ni, except for 20 and 30 mol/O HCOOH, in which feeble passitivity was observed. The organometallic compounds dibutyltin dichloride, phenyltin trichloride, diphenyltin dichloride, and triphenyltin chloride ([C[sub 6]H[sub 5

  15. Analysis of trace impurities in organometallic semiconductor grade reagent materials using electrothermal vaporization - inductively coupled plasma spectrometry

    SciTech Connect

    Argentine, M.D.

    1993-12-31

    Trace impurity determinations in volatile, pyrophoric organometallic materials is complicated owing to its chemical nature. Furthermore, trends toward high semiconductor circuit density demand that impurity determinations are performed at increasingly low levels. Volatility of the impurities is also desired as it plays a significant role in impurity incorporation in semiconductor products. Determination of both volatile and nonvolatile impurities in semiconductor-grade organometallic reagent materials has been accomplished using electrothermal vaporization-inductively coupled plasma spectrometry. Solid or liquid materials can be dispensed directly onto a graphite microboat, and application of an appropriate time-temperature ramp allows separation of impurities based on volatility. Temporal separation allows quantitative capabilities on both volatile and nonvolatile signals in a single ETV run. Calibration efforts for volatile impurities have been compared with results from exponential dilution and direct vapor sampling techniques. Nonvolatile impurity determinations can be reasonably performed with aqueous external standard calibration. Inductively coupled plasma-mass spectrometry provides an alternate and more sensitive, multielement detection method. Several spectroscopic and non-spectroscopic difficulties with volatile impurity detection remain. Nonetheless, qualitative and semiquantitative (<50% RSD) determination of most impurities may be performed in a single ETV run.

  16. Back-extraction of trace elements from organometallic-halide extracts for determination by flameless atomic absorption spectrometry

    USGS Publications Warehouse

    Clark, J.R.; Viets, J.G.

    1981-01-01

    The Methyl isobutyl ketone-Amine synerGistic Iodkte Complex (MAGIC) extraction system offers the advantage that a large number of trace elements can be rapidly determined with a single sample preparation procedure. However, many of the elements extracted by the MAGIC system form volatile organometallic halide salts when the organic extract is heated in the graphite furnace. High concentrations of some elements such as Cu and Zn extracted by the system from anomalous geological samples produce serious interferences when certain other elements are determined by flameless atomic absorption. Stripping systems have been developed using solutions of HNO3, H2SO4, and CH3COOH individually or combined with H2O2 in order to circumvent these problems. With these systems most of the elements in the organic extract can be sequentially stripped into an aqueous phase. Organometallic volatilization and the most serious interelement interferences, therefore, can be eliminated by stripping with various combinations of reagents in a series of steps.

  17. Optical properties of organometallic perovskite: An ab initio study using relativistic GW correction and Bethe-Salpeter equation

    NASA Astrophysics Data System (ADS)

    Ahmed, Towfiq; La-o-vorakiat, C.; Salim, T.; Lam, Y. M.; Chia, Elbert E. M.; Zhu, Jian-Xin

    2014-12-01

    In the development of highly efficient photovoltaic cells, solid perovskite systems have demonstrated unprecedented promise, with the figure of merit exceeding nineteen percent of efficiency. In this paper, we investigate the optical and vibrational properties of organometallic cubic perovskite CH3NH3PbI3 using first-principles calculations. For accurate theoretical description, we go beyond conventional density functional theory (DFT), and calculate optical conductivity using relativistic quasi-particle (GW) correction. Incorporating these many-body effects, we further solve Bethe-Salpeter equations (BSE) for excitons, and found enhanced optical conductivity near the gap edge. Due to the presence of organic methylammonium cations near the center of the perovskite cell, the system is sensitive to low-energy vibrational modes. We estimate the phonon modes of CH3NH3PbI3 using a small displacement approach, and further calculate the infrared (IR) absorption spectra. Qualitatively, our calculations of low-energy phonon frequencies are in good agreement with our terahertz measurements. Therefore, for both energy scales (around 1.5 eV and 0-20 meV), our calculations reveal the importance of many-body effects and their contributions to the desirable optical properties in the cubic organometallic perovskites system.

  18. Investigation of the Hydrolysis of Perovskite Organometallic Halide CH3NH3PbI3 in Humidity Environment

    NASA Astrophysics Data System (ADS)

    Zhao, Jiangtao; Cai, Bing; Luo, Zhenlin; Dong, Yongqi; Zhang, Yi; Xu, Han; Hong, Bin; Yang, Yuanjun; Li, Liangbin; Zhang, Wenhua; Gao, Chen

    2016-02-01

    Instability of emerging perovskite organometallic halide in humidity environment is the biggest obstacle for its potential applications in solar energy harvest and electroluminescent display. Understanding the detailed decay mechanism of these materials in moisture is a critical step towards the final appropriate solutions. As a model study presented in this work, in situ synchrotron radiation x-ray diffraction was combined with microscopy and gravimetric analysis to study the degradation process of CH3NH3PbI3 in moisture, and the results reveal that: 1) intermediate monohydrated CH3NH3PbI3·H2O is detected in the degradation process of CH3NH3PbI3 and the final decomposition products are PbI2 and aqueous CH3NH3I; 2) the aqueous CH3NH3I could hardly further decompose into volatile CH3NH2, HI or I2; 3) the moisture disintegrate CH3NH3PbI3 and then alter the distribution of the decomposition products, which leads to an incompletely-reversible reaction of CH3NH3PbI3 hydrolysis and degrades the photoelectric properties. These findings further elucidate the picture of hydrolysis process of perovskite organometallic halide in humidity environment.

  19. A physical simulation study of the effect of thermal variations on the secondary dendrite arm spacing in a Ni-based superalloy

    NASA Astrophysics Data System (ADS)

    Rahimian, Mehdi; Milenkovic, Srdjan; Sabirov, Ilchat

    2014-02-01

    The effect of thermal variations on the secondary dendrite arm spacing (SDAS) in a MAR-M247 Ni-based superalloy has been studied by a novel method based on a physical simulation of melting/solidification experiments with a constant cooling rate and variable temperature gradient. The method proved to be effective as it yielded a spread of microstructures corresponding to a range of well-controlled solidification rates in a single melting/solidification experiment. In addition, it has been demonstrated that SDAS is better related to the solidification rate than to the cooling rate in cases when significant variations of thermal parameters during the solidification process occur.

  20. Nondestructive evaluation of creep damage and life prediction of Ni-base superalloy used in advanced gas turbine blades by electrochemical technique

    NASA Astrophysics Data System (ADS)

    Komazaki, Shin-ichi; Shoji, Tetsuo; Abe, Iwao; Okada, Ikuo

    1999-12-01

    In order to develop a creep life assessment technique for directionally solidified Ni-base superalloy CM247LC, changes in electrochemical properties due to creep have been investigated. Experimental results on electrochemical polarization measurements revealed that the peak current density "Ip" and "Ipr" which appeared at a specific potential during potentiodynamic polarization reactivation measurements in dilute glyceregia solution linearly increased with a life fraction in early stage of the creep life and were uniquely correlated with Arrhenius type parameter "(t/tr)exp(-Qc/RT)." As a consequence, the creep life fraction can be estimated with high accuracy by the electrochemical technique.

  1. Polybenzimidazole compounds

    DOEpatents

    Klaehn, John R [Idaho Falls, ID; Peterson, Eric S [Idaho Falls, ID; Orme, Christopher J [Shelley, ID; Jones, Michael G [Chubbuck, ID; Wertsching, Alan K [Idaho Falls, ID; Luther, Thomas A [Idaho Falls, ID; Trowbridge, Tammy L [Idaho Falls, ID

    2011-11-22

    A PBI compound includes imidazole nitrogens at least a portion of which are substituted with a moiety containing a carbonyl group, the substituted imidazole nitrogens being bonded to carbon of the carbonyl group. At least 85% of the nitrogens may be substituted. The carbonyl-containing moiety may include RCO--, where R is alkoxy or haloalkyl. The PBI compound may exhibit a first temperature marking an onset of weight loss corresponding to reversion of the substituted PBI that is less than a second temperature marking an onset of decomposition of an otherwise identical PBI compound without the substituted moiety. The PBI compound may be included in separatory media. A substituted PBI synthesis method may include providing a parent PBI in a less than 5 wt % solvent solution. Substituting may use more than 5 equivalents in relation to the imidazole nitrogens to be substituted.

  2. Polybenzimidazole compounds

    DOEpatents

    Klaehn, John R.; Peterson, Eric S.; Wertsching, Alan K.; Orme, Christopher J.; Luther, Thomas A.; Jones, Michael G.

    2010-08-10

    A PBI compound that includes imidazole nitrogens, at least a portion of which are substituted with an organic-inorganic hybrid moiety. At least 85% of the imidazole nitrogens may be substituted. The organic-inorganic hybrid moiety may be an organosilane moiety, for example, (R)Me.sub.2SiCH.sub.2--, where R is selected from among methyl, phenyl, vinyl, and allyl. The PBI compound may exhibit similar thermal properties in comparison to the unsubstituted PBI. The PBI compound may exhibit a solubility in an organic solvent greater than the solubility of the unsubstituted PBI. The PBI compound may be included in separatory media. A substituted PBI synthesis method may include providing a parent PBI in a less than 5 wt % solvent solution. Substituting may occur at about room temperature and/or at about atmospheric pressure. Substituting may use at least five equivalents in relation to the imidazole nitrogens to be substituted or, preferably, about fifteen equivalents.

  3. Synthesis and Migratory-Insertion Reactivity of CpMo(CO)[subscript3](CH[subscript3]): Small-Scale Organometallic Preparations Utilizing Modern Glovebox Techniques

    ERIC Educational Resources Information Center

    Whited, Matthew T.; Hofmeister, Gretchen E.

    2014-01-01

    Experiments are described for the reliable small-scale glovebox preparation of CpMo(CO)[subscript 3](CH[subscript 3]) and acetyl derivatives thereof through phosphine-induced migratory insertion. The robust syntheses introduce students to a variety of organometallic reaction mechanisms and glovebox techniques, and they are easily carried out…

  4. Grubbs's Cross Metathesis of Eugenol with cis-2-butene-1, 4-diol to Make a Natural Product: An Organometallic Experiment for the Undergraduate Lab

    ERIC Educational Resources Information Center

    Taber, Douglass F.; Frankowski, Kevin J.

    2006-01-01

    A modified experimental procedure for the one-step synthesis that is suitable for the undergraduate organic lab is presented. In the course of work towards the more routine use of air-sensitive organometallic complexes such as the Grubb's catalyst, the natural product (E)-4-(4-hydroxy-3-methoxyphenyl) but-2-en-ol, 4, was synthesized.

  5. Synthesis and Catalytic Activity of Ruthenium-Indenylidene Complexes for Olefin Metathesis: Microscale Experiments for the Undergraduate Inorganic or Organometallic Laboratories

    ERIC Educational Resources Information Center

    Pappenfus, Ted M.; Hermanson, David L.; Ekerholm, Daniel P.; Lilliquist, Stacie L.; Mekoli, Megan L.

    2007-01-01

    A series of experiments for undergraduate laboratory courses (e.g., inorganic, organometallic or advanced organic) have been developed. These experiments focus on understanding the design and catalytic activity of ruthenium-indenylidene complexes for olefin metathesis. Included in the experiments are the syntheses of two ruthenium-indenylidene…

  6. Multi-stimuli-responsive organometallic gels based on ferrocene-linked poly(aryl ether) dendrons: reversible redox switching and Pb2+-ion sensing.

    PubMed

    Lakshmi, Neelakandan Vidhya; Mandal, Dipendu; Ghosh, Sundargopal; Prasad, Edamana

    2014-07-14

    We describe the design, synthesis, and "stimuli-responsive" study of ferrocene-linked Fréchet-type [poly(aryl ether)]-dendron-based organometallic gels, in which the ferrocene moiety is attached to the dendron framework through an acyl hydrazone linkage. The low-molecular-weight gelators (LMWGs) form robust gels in both polar and non-polar solvent/solvent mixtures. The organometallic gels undergo stimuli-responsive behavior through 1) thermal, 2) chemical, and 3) electrochemical methods. Among them, conditions 1 and 3 lead to seamlessly reversible with repeated cycles of identical efficiency. Results indicate that the flexible nature of the poly(aryl ether) dendron framework plays a key role in retaining the reversible electrochemical behavior of ferrocene moiety in the LMWGs. Further, the organometallic gelators have exhibited unique selectivity towards Pb(2+) ions (detection limit ≈10(-8)  M). The metal ion-sensing results in a gel-sol phase transition associated with a color change visible to the naked eye. Most importantly, decomplexing the metal ion from the system leads to the regeneration of the initial gel morphology, indicating the restoring ability of the organometallic gel. The metal-ligand binding nature has been analyzed by using (1)H NMR spectroscopy, mass spectrometry, and DFT calculations.

  7. Supramolecular Organometallic Polymer Chemistry: Self-Assembly of a Novel Poly(ferrocene)-b-polysiloxane-b-poly(ferrocene) Triblock Copolymer in Solution.

    PubMed

    Resendes; Massey; Dorn; Power; Winnik; Manners

    1999-09-01

    Micelles with unprecedented flowerlike arrangements of the poly(ferrocene) cores (shown in the TEM image) are among the supramolecular architectures generated in the self-assembly of a novel organometallic triblock copolymer from silicon-bridged [1]ferrocenophane monomers and [Me(2)SiO](3) in hexane, a solvent selective for the central polysiloxane block.

  8. Correction: NanoSIMS analysis of an isotopically labelled organometallic ruthenium(II) drug to probe its distribution and state in vitro.

    PubMed

    Lee, Ronald F S; Escrig, Stéphane; Croisier, Marie; Clerc-Rosset, Stéphanie; Knott, Graham W; Meibom, Anders; Davey, Curt A; Johnsson, Kai; Dyson, Paul J

    2015-11-28

    Correction for 'NanoSIMS analysis of an isotopically labelled organometallic ruthenium(II) drug to probe its distribution and state in vitro' by Ronald F. S. Lee et al., Chem. Commun., 2015, DOI: 10.1039/c5cc06983a.

  9. A deadly organometallic luminescent probe: anticancer activity of a ReI bisquinoline complex.

    PubMed

    Kitanovic, Igor; Can, Suzan; Alborzinia, Hamed; Kitanovic, Ana; Pierroz, Vanessa; Leonidova, Anna; Pinto, Antonio; Spingler, Bernhard; Ferrari, Stefano; Molteni, Roberto; Steffen, Andreas; Metzler-Nolte, Nils; Wölfl, Stefan; Gasser, Gilles

    2014-02-24

    The photophysical properties of [Re(CO)3 (L-N3)]Br (L-N3 =2-azido-N,N-bis[(quinolin-2-yl)methyl]ethanamine), which could not be localized in cancer cells by fluorescence microscopy, have been revisited in order to evaluate its use as a luminescent probe in a biological environment. The Re(I) complex displays concentration-dependent residual fluorescence besides the expected phosphorescence, and the nature of the emitting excited states have been evaluated by DFT and time-dependent (TD) DFT methods. The results show that fluorescence occurs from a (1) LC/MLCT state, whereas phosphorescence mainly stems from a (3) LC state, in contrast to previous assignments. We found that our luminescent probe, [Re(CO)3 (L-N3)]Br, exhibits an interesting cytotoxic activity in the low micromolar range in various cancer cell lines. Several biochemical assays were performed to unveil the cytotoxic mechanism of the organometallic Re(I) bisquinoline complex. [Re(CO)3 (L-N3)]Br was found to be stable in human plasma indicating that [Re(CO)3 (L-N3)]Br itself and not a decomposition product is responsible for the observed cytotoxicity. Addition of [Re(CO)3 (L-N3)]Br to MCF-7 breast cancer cells grown on a biosensor chip micro-bioreactor immediately led to reduced cellular respiration and increased glycolysis, indicating a large shift in cellular metabolism and inhibition of mitochondrial activity. Further analysis of respiration of isolated mitochondria clearly showed that mitochondrial respiratory activity was a direct target of [Re(CO)3 (L-N3)]Br and involved two modes of action, namely increased respiration at lower concentrations, potentially through increased proton transport through the inner mitochondrial membrane, and efficient blocking of respiration at higher concentrations. Thus, we believe that the direct targeting of mitochondria in cells by [Re(CO)3 (L-N3)]Br is responsible for the anticancer activity.

  10. Organometallic photovoltaics: a new and versatile approach for harvesting solar energy using conjugated polymetallaynes.

    PubMed

    Wong, Wai-Yeung; Ho, Cheuk-Lam

    2010-09-21

    Energy remains one of the world's great challenges. Growing concerns about limited fossil fuel resources and the accumulation of CO(2) in the atmosphere from burning those fuels have stimulated tremendous academic and industrial interest. Researchers are focusing both on developing inexpensive renewable energy resources and on improving the technologies for energy conversion. Solar energy has the capacity to meet increasing global energy needs. Harvesting energy directly from sunlight using photovoltaic technology significantly reduces atmospheric emissions, avoiding the detrimental effects of these gases on the environment. Currently inorganic semiconductors dominate the solar cell production market, but these materials require high technology production and expensive materials, making electricity produced in this manner too costly to compete with conventional sources of electricity. Researchers have successfully fabricated efficient organic-based polymer solar cells (PSCs) as a lower cost alternative. Recently, metalated conjugated polymers have shown exceptional promise as donor materials in bulk-heterojunction solar cells and are emerging as viable alternatives to the all-organic congeners currently in use. Among these metalated conjugated polymers, soluble platinum(II)-containing poly(arylene ethynylene)s of variable bandgaps (∼1.4-3.0 eV) represent attractive candidates for a cost-effective, lightweight solar-energy conversion platform. This Account highlights and discusses the recent advances of this research frontier in organometallic photovoltaics. The emerging use of low-bandgap soluble platinum-acetylide polymers in PSCs offers a new and versatile strategy to capture sunlight for efficient solar power generation. Properties of these polyplatinynes--including their chemical structures, absorption coefficients, bandgaps, charge mobilities, accessibility of triplet excitons, molecular weights, and blend film morphologies--critically influence the device

  11. Performance of chromia- and alumina-forming Fe- and Ni-base alloys exposed to metal dusting environments: The effect of water vapor and temperature

    SciTech Connect

    Rouaix-Vande Put, Aurelie; Unocic, Kinga A.; Brady, Michael P.; Pint, Bruce A.

    2015-11-18

    Fe- and Ni-base alloys including an alumina-forming austenitic alloy were exposed for 500 h under metal dusting environments with varying temperature, gas composition and total pressure. For one H2–CO–CO2–H2O environment, the increase in temperature from 550 to 750 °C generally decreased metal dusting. When H2O was added to a H2–CO–CO2 environment at 650 °C, the metal dusting attack was reduced. Even after 5000 h at a total pressure of 9.1 atm with 20%H2O, the higher alloyed specimens retained a thin protective oxide. Lastly, for gas mixtures containing little or no H2O, the Fe-base alloys were less resistant to metal dusting than Ni-base alloys.

  12. Coupling the Phase Field Method for diffusive transformations with dislocation density-based crystal plasticity: Application to Ni-based superalloys

    NASA Astrophysics Data System (ADS)

    Cottura, M.; Appolaire, B.; Finel, A.; Le Bouar, Y.

    2016-09-01

    A phase field model is coupled to strain gradient crystal plasticity based on dislocation densities. The resulting model includes anisotropic plasticity and the size-dependence of plastic activity, required when plasticity is confined in region below few microns in size. These two features are important for handling microstructure evolutions during diffusive phase transformations that involve plastic deformation occurring in confined areas such as Ni-based superalloys undergoing rafting. The model also uses a storage-recovery law for the evolution of the dislocation density of each glide system and a hardening matrix to account for the short-range interactions between dislocations. First, it is shown that the unstable modes during the morphological destabilization of a growing misfitting circular precipitate are selected by the anisotropy of plasticity. Then, the rafting of γ‧ precipitates in a Ni-based superalloy is investigated during [100] creep loadings. Our model includes most of the important physical phenomena accounted for during the microstructure evolution, such as the presence of different crystallographic γ‧ variants, their misfit with the γ matrix, the elastic inhomogeneity and anisotropy, the hardening, anisotropy and viscosity of plasticity. In agreement with experiments, the model predicts that rafting proceeds perpendicularly to the tensile loading axis and it is shown that plasticity slows down significantly the evolution of the rafts.

  13. Cationization of organometallo carbonyl compounds by fast ion bombardment

    NASA Astrophysics Data System (ADS)

    Siuzdak, Gary; Wendeborn, Sebastian V.; Nicolaou, K. C.

    1992-01-01

    Organodicobalt, organochromium, and organomolybdenum carbonyl complexes have been studied using fast ion bombardment mass spectrometry. It has been found that the addition of cesium iodide to the liquid matrix, m-NBA, can significantly enhance the ability to observed the precursor ions of these organometallics through charge localization. In most cases the [M + Cs]+ ions were more abundant than the radical cations M-, the protonated molecules [M + H]+, or the sodium cationized molecules [M + Na]+ which were either unobservable or less intense than those treated with the cesium iodide salt solution. The decomposition of the compounds took place primarily through the successive loss of carbonyls from the radical cation with some carbonyl loss observed through the protonated and cationized species. The FAB matrix ions produced when cesium iodide was added to m-NBA also allowed for internal calibration.

  14. Laser photochemistry of gallium-containing compounds. [Trimethylgallium

    SciTech Connect

    Baughcum, S.L.; Oldenborg, R.C.

    1986-01-01

    The production of gas-phase gallium atoms in the photolysis of trimethylgallium has been investigated at 193 nm and at other laser wavelengths. Ground state (4 /sup 2/P/sup 0//sub 1/2) and metastable (4 /sup 2/P/sup 0//sub 3/2/) gallium atoms are detected using laser-induced fluorescence techniques. Our results indicate that gallium atoms continue to be produced at long times after the laser pulse. The observed dependence on photolysis laser fluence, trimethylgallium pressure, and buffer gas pressure are consistent with a mechanism in which highly excited gallium methyl radicals undergo unimolecular decomposition to produce gallium atoms. Since this process is observed to happen on the time scale of hundreds of microseconds, these results have important implications for studies of metal deposition and direct laser writing by laser photolysis of organometallic compounds. 31 refs., 5 figs.

  15. Multipurpose Compound

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Specially formulated derivatives of an unusual basic compound known as Alcide may be the answer to effective treatment and prevention of the disease bovine mastitis, a bacterial inflammation of a cow's mammary gland that results in loss of milk production and in extreme cases, death. Manufactured by Alcide Corporation the Alcide compound has killed all tested bacteria, virus and fungi, shortly after contact, with minimal toxic effects on humans or animals. Alcide Corporation credits the existence of the mastitis treatment/prevention products to assistance provided the company by NERAC, Inc.

  16. Perfluorinated Compounds

    EPA Science Inventory

    Perfluorinated compounds such as the perfluoroalkyl acids (PFAAs) and their derivatives are important man-made chemicals that have wide consumer and industrial applications. They are relatively contemporary chemicals, being in use only since the 1950s, and until recently, have be...

  17. Structurally defined allyl compounds of main group metals: coordination and reactivity.

    PubMed

    Lichtenberg, Crispin; Okuda, Jun

    2013-05-10

    Organometallic allyl compounds are important as allylation reagents in organic synthesis, as polymerization catalysts, and as volatile metal precursors in material science. Whereas the allyl chemistry of synthetically relevant transition metals such as palladium and of the lanthanoids is well-established, that of main group metals has been lagging behind. Recent progress on allyl complexes of Groups 1, 2, and 12-16 now provides a more complete picture. This is based on a fundamental understanding of metal-allyl bonding interactions in solution and in the solid state. Furthermore, reactivity trends have been rationalized and new types of allyl-specific reactivity patterns have been uncovered. Key features include 1) the exploitation of the different types of metal-allyl bonding (highly ionic to predominantly covalent), 2) the use of synergistic effects in heterobimetallic compounds, and 3) the adjustment of Lewis acidity by variation of the charge of allyl compounds.

  18. Spin-State Effects on the Thermal Dihydrogen Release from Solid-State [MH(η2-H2)dppe2]+ (M = Fe, Ru, Os) Organometallic Complexes for Hydrogen Storage Applications

    PubMed Central

    2015-01-01

    Mössbauer spectroscopy, experimental thermodynamic measurements, and computational studies were performed to investigate the properties of molecular hydrogen binding to the organometallic fragments [MHdppe2]+ (M = Fe, Ru, Os; dppe =1,2-bis(diphenylphosphino)ethane) to form the dihydrogen complex fragments [MH(η2-H2)dppe2]+. Mössbauer spectroscopy showed that the dehydrogenated complex [FeHdppe2]+ adopts a geometry consistent with the triplet spin state, transitioning to a singlet state complex upon addition of the dihydrogen molecule in a manner similar to the previously studied dinitrogen complexes. From simulations, this spin transition behavior was found to be responsible for the strong binding behavior experimentally observed in the iron complex. Spin-singlet to spin-singlet transitions were found to exhibit thermodynamics consistent with the 5d > 3d > 4d binding trend observed for other transition metal dihydrogen complexes. Finally, the method for distinguishing between dihydrogen and dihydride complexes based on partial quadrupole splittings observed in Mössbauer spectra was confirmed, providing a tool for further characterization of these unique species for Mössbauer active compounds. PMID:24803973

  19. Vibrational spectral characterization, NLO studies and charge transfer analysis of the organometallic material L-Alanine cadmium chloride

    NASA Astrophysics Data System (ADS)

    Arun Sasi, B. S.; Bright, K. C.; James, C.

    2016-01-01

    An organometallic nonlinear crystal, L-Alanine Cadmium Chloride (LACC) was synthesized by slow evaporation technique. The effects of hydrogen bonding on the structure, binding of ligand to metal ion, natural orbital occupancies, and vibrational frequencies were investigated using density functional theory (DFT) with the combined B3LYP and LANL2DZ basis set. Vibrational assignments were made on the basis of calculated potential energy distribution values from MOLVIB program. The topological analysis of electron localization function (ELF) provides basin population N (integrated density over the attractor basin), standard deviation (σ), and their relative fluctuation, defined as λ = σ2/N, which are sensitive criteria of delocalization. The molecular stability, electronic exchange interaction, and bond strength of the molecule were studied by natural bond orbital (NBO) analysis. The second harmonic generation (SHG) efficiency was determined using Kurtz and Perry method. Natural bond orbital analysis was carried out to study various intramolecular interactions that are responsible for the stabilization of the molecule.

  20. Quaternized and Thiazole-Functionalized Free Radical-Generating Organometallic Dendrimers as Antimicrobial Platform against Multidrug-Resistant Microorganisms.

    PubMed

    Abd-El-Aziz, Alaa S; Agatemor, Christian; Etkin, Nola; Bissessur, Rabin; Overy, David; Lanteigne, Martin; McQuillan, Katherine; Kerr, Russell G

    2017-03-31

    New macromolecules such as dendrimers are increasingly needed to drive breakthroughs in diverse areas, for example, healthcare. Here, the authors report hybrid antimicrobial dendrimers synthesized by functionalizing organometallic dendrimers with quaternary ammonium groups or 2-mercaptobenzothiazole. The functionalization tunes the glass transition temperature and antimicrobial activities of the dendrimers. Electron paramagnetic resonance spectroscopy reveals that the dendrimers form free radicals, which have significant implications for catalysis and biology. In vitro antimicrobial assays indicate that the dendrimers are potent antimicrobial agents with activity against multidrug-resistant pathogens such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium as well as other microorganisms. The functionalization increases the activity, especially in the quaternary ammonium group-functionalized dendrimers. Importantly, the activities are selective because human epidermal keratinocytes cells and BJ fibroblast cells exposed to the dendrimers are viable after 24 h.

  1. Synthesis, characterization and cellular location of cytotoxic constitutional organometallic isomers of rhenium delivered on a cyanocobalmin scaffold.

    PubMed

    Santoro, Giuseppe; Zlateva, Theodora; Ruggi, Albert; Quaroni, Luca; Zobi, Fabio

    2015-04-21

    Constitutional isomers of cyanocobalamin adducts based on a fluorescent rhenium tris-carbonyl diimine complex were prepared, characterized and tested against PC-3 cancer cells. The adducts differ only in the relative binding position of the organometallic species which is either bound at the cyano or the 5'-hydroxo group of vitamin B12. When tested for their cytotoxic potency, the species showed IC50 values in the low μM rage. Upon conjugation to the vitamin an energy transfer process causes an extremely low quantum yield of fluorescence emission, making the conjugates unsuitable for fluorescence imaging. However, by exploiting the vibrational signature of the fac-[Re(CO)3](+) core, their cellular distribution was evaluated via FTIR spectromicroscopy.

  2. Method of Continuous Variations: Applications of Job Plots to the Study of Molecular Associations in Organometallic Chemistry[**

    PubMed Central

    Renny, Joseph S.; Tomasevich, Laura L.; Tallmadge, Evan H.; Collum, David B.

    2014-01-01

    Applications of the method of continuous variations—MCV or the Method of Job—to problems of interest to organometallic chemists are described. MCV provides qualitative and quantitative insights into the stoichiometries underlying association of m molecules of A and n molecules of B to form AmBn. Applications to complex ensembles probe associations that form metal clusters and aggregates. Job plots in which reaction rates are monitored provide relative stoichiometries in rate-limiting transition structures. In a specialized variant, ligand- or solvent-dependent reaction rates are dissected into contributions in both the ground states and transition states, which affords insights into the full reaction coordinate from a single Job plot. Gaps in the literature are identified and critiqued. PMID:24166797

  3. Organometallic Vapor-Phase Epitaxial Growth and Characterization of GaAs/Zn(S, Se) Multilayered Structures

    NASA Astrophysics Data System (ADS)

    Fujita, Shigeo; Murawala, Prakash A.; Maruo, Seiji; Tsuji, Osamu; Fujita, Shizuo

    1991-01-01

    We report growth conditions of lattice-matched dissimilar semiconductor multilayered structures of GaAs/Zn(S, Se) systems by organometallic vapor-phase epitaxy (OMVPE). Since the optimum growth temperature for GaAs is much higher than that of Zn(S, Se), we performed low-temperature growth (470°C) of GaAs by photo-assisted OMVPE. A smooth growth surface of GaAs on Zn(S, Se) was achieved by lattice-matching, sufficient preflow of triethylarsenic (TEAs) and a Zn-stabilized surface before starting the growth of GaAs; hence we succeeded in the fabrication of a ZnSSe/GaAs/ZnSSe double hetero (DH) structure and a superlattice. Thermal annealing of the DH structure showed no appreciable Zn diffusion into GaAs up to 650°C but showed thermal stability at the interface up to 550°C.

  4. Divergence between organometallic and single-electron-transfer mechanisms in copper(II)-mediated aerobic C-H oxidation.

    PubMed

    Suess, Alison M; Ertem, Mehmed Z; Cramer, Christopher J; Stahl, Shannon S

    2013-07-03

    Copper(II)-mediated C-H oxidation is the subject of extensive interest in synthetic chemistry, but the mechanisms of many of these reactions are poorly understood. Here, we observe different products from Cu(II)-mediated oxidation of N-(8-quinolinyl)benzamide, depending on the reaction conditions. Under basic conditions, the benzamide group undergoes directed C-H methoxylation or chlorination. Under acidic conditions, the quinoline group undergoes nondirected chlorination. Experimental and computational mechanistic studies implicate an organometallic C-H activation/functionalization mechanism under the former conditions and a single-electron-transfer mechanism under the latter conditions. This rare observation of divergent, condition-dependent mechanisms for oxidation of a single substrate provides a valuable foundation for understanding Cu(II)-mediated C-H oxidation reactions.

  5. Synthesis of polystyrene microspheres and functionalization with Pd(0) nanoparticles to perform bioorthogonal organometallic chemistry in living cells.

    PubMed

    Unciti-Broceta, Asier; Johansson, Emma M V; Yusop, Rahimi M; Sánchez-Martín, Rosario M; Bradley, Mark

    2012-05-31

    We have developed miniaturized heterogeneous Pd(0)-catalysts (Pd(0)-microspheres) with the ability to enter cells, stay harmlessly within the cytosol and mediate efficient bioorthogonal organometallic chemistries (e.g., allylcarbamate cleavage and Suzuki-Miyaura cross-coupling). This approach is a major addition to the toolbox available for performing chemical reactions within cells. Here we describe a full protocol for the synthesis of the Pd(0)-microspheres from readily available starting materials (by the synthesis of size-controlled amino-functionalized polystyrene microspheres), as well as for their characterization (electron microscopy and palladium quantitation) and functional validation ('in solution' and 'in cytoplasm' conversions). From the beginning of the synthesis to functional evaluation of the catalytic device requires 5 d of work.

  6. Square-micrometer-sized, free-standing organometallic sheets and their square-centimeter-sized multilayers on solid substrates.

    PubMed

    Zheng, Zhikun; Ruiz-Vargas, Carlos S; Bauer, Thomas; Rossi, Antonella; Payamyar, Payam; Schütz, Andri; Stemmer, Andreas; Sakamoto, Junji; Schlüter, A Dieter

    2013-11-01

    Oligofunctional terpyridine-based monomers are spread at an air/water interface, where they are connected with transition metal salts such as Fe(II) into mechanically coherent monolayer sheets of macroscopic dimension. The conversions of these processes are determined by XPS for several monomer/metal ion combinations. The sheets are transferred onto TEM grids, the 20 × 20 square micrometer sized holes of which can be spanned. AFM indentation experiments provide in-plane elastic moduli which are compared with naturally occurring sheets such as graphene. The new organometallic sheets are also used to create multilayer assemblies on square centimeter length scales on solid substrates. Finally some directions are provided where this research can lead to in future and where its application potential lies.

  7. Engineered Organometallic Polymer and Hybrid Systems Containing Nanoparticles and/or Poly(ferrocenylsilanes)

    NASA Astrophysics Data System (ADS)

    Roskov, Kristen Ekiert

    electrospun fibers, and the fibers have likewise been aligned to permit longrange orientation order at both the nanoscale and macroscale. This is an important consideration in the fabrication of devices spanning multiple size scales. The GNRs within nano/microfibers exhibit excellent alignment with their longitudinal axis parallel to the fiber axis. Optical absorbance spectroscopy measurements reveal that the longitudinal surface plasmon resonance bands of the aligned GNRs are highly anisotropic, depending on polarization angle, and that maximum absorption occurs when polarization is parallel to the fiber axis. Lastly, blends of hydrophobic and hydrophilic polymers have been prepared to control the spatial position of SPIONs within electrospun fibers on the basis of thermodynamic compatibility. In this case, TEM confirms that a core-sheath nanostructure naturally forms due to polymer-polymer phase separation and that the hydrophobic nanoparticles are sequestered in one preferred phase. Lastly, a nanocomposite fiber is created using only one entity, the organometallic polymer poly(ferrocenylsilane) (PFS)and its crystalline structure is probed alone and in the presence of SPIONs. Block copolymer cylindrical micelles of PFS-b-poly(isoprene) (PI) are crosslinked within an elastomeric matrix of poly (vinylmethoxysilane) (PVMS) and found to maintain their crystalline structure with the target application being nanowires in soft electronics.

  8. DFT and time-resolved IR investigation of electron transfer between photogenerated 17- and 19-electron organometallic radicals

    SciTech Connect

    Cahoon, James B.; Kling, Matthias F.; Sawyer, Karma R.; Andersen, Lars K.; Harris, Charles B.

    2008-04-30

    The photochemical disproportionation mechanism of [CpW(CO){sub 3}]{sub 2} in the presence of Lewis bases PR{sub 3} was investigated on the nano- and microsecond time-scales with Step-Scan FTIR time-resolved infrared spectroscopy. 532 nm laser excitation was used to homolytically cleave the W-W bond, forming the 17-electron radicals CpW(CO){sub 3} and initiating the reaction. With the Lewis base PPh{sub 3}, disproportionation to form the ionic products CpW(CO){sub 3}PPh{sub 3}{sup +} and CpW(CO){sub 3}{sup -} was directly monitored on the microsecond time-scale. Detailed examination of the kinetics and concentration dependence of this reaction indicates that disproportionation proceeds by electron transfer from the 19-electron species CpW(CO){sub 3}PPh{sub 3} to the 17-electron species CpW(CO){sub 3}. This result is contrary to the currently accepted disproportionation mechanism which predicts electron transfer from the 19-electron species to the dimer [CpW(CO){sub 3}]{sub 2}. With the Lewis base P(OMe){sub 3} on the other hand, ligand substitution to form the product [CpW(CO){sub 2}P(OMe){sub 3}]{sub 2} is the primary reaction on the microsecond time-scale. Density Functional Theory (DFT) calculations support the experimental results and suggest that the differences in the reactivity between P(OMe){sub 3} and PPh{sub 3} are due to steric effects. The results indicate that radical-to-radical electron transfer is a previously unknown but important process for the formation of ionic products with the organometallic dimer [CpW(CO){sub 3}]{sub 2} and may also be applicable to the entire class of organometallic dimers containing a single metal-metal bond.

  9. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2003-01-01

    Seawater and natural brines accounted for about 60 percent of U.S. magnesium compounds production during 2002. Dead-burned and caustic-calcined magnesias were recovered from seawater by Premier Chemicals in Florida. They were also recovered from well brines in Michigan by Dow Chemical, Martin Marietta Magnesia Specialties and Rohm & Haas. And they were recovered from magnesite in Nevada by Premier Chemicals.

  10. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2006-01-01

    In 2005, seawater and natural brines accounted for 51% of US magnesium compounds production. World magnesia production was estimated to be 14.5 Mt. Most of the production came from China, North Korea, Russia and Turkey. Although no specific production figures are available, Japan and the United States are estimated to account for almost one-half of the world's capacity from seawater and brines.

  11. Effects of sulfur impurity on the scale adhesion behavior of a desulfurized Ni-based superalloy aluminized by chemical vapor deposition

    SciTech Connect

    Lee, W.Y.; Wright, I.G.; Pint, B.A.; Liwa, P.K.

    1998-03-01

    The surface of a single-crystal Ni-based superalloy, which contained a bulk sulfur content of {approximately} 0.4 ppmw, was aluminized in a hot-wall chemical vapor deposition (CVD) reactor, using AlCl{sub 3} and H{sub 2} as gaseous precursors, at 1,100 C. The chemical composition and microstructure of the resulting aluminide coating were characterized with particular emphasis on sulfur incorporation as an impurity during aluminizing. Depth profiling by glow-discharge mass spectroscopy (GDMS) was used as a qualitative means of assessing the level of sulfur in the coating structure. Sulfur contamination, which was initially observed at the coating surface and the substrate-coating interface, could be reduced by some minor reactor modifications. With the reduced sulfur content, scale adhesion on the surface of the aluminide grains of the coating was significantly improved during cyclic oxidation, whereas scale spallation at the coating`s grain boundaries became more apparent.

  12. In situ determination of {gamma}{prime} phase volume fraction and of relations between lattice parameters and precipitate morphology in Ni-based single crystal superalloy

    SciTech Connect

    Royer, A.; Bastie, P.; Veron, M.

    1998-09-18

    Diffraction profiles of single crystal Ni-based superalloy samples with different microstructures were measured in situ up to the complete solutionizing of the {gamma}{prime} phase, using a high resolution triple crystal diffactometer and high energy synchrotron radiation (150 keV, {lambda} = 0.08 {angstrom}). A comparison between an undeformed sample and creep-deformed specimens with various resultant microstructures evidenced a relation between the lattice parameter distribution, the {gamma}{prime} precipitate microstructure and the sign of the connectivity. It was shown that a deformation induces a change in the relative volume cell of {gamma} and {gamma}{prime} phases. Moreover, the high resolution of the experimental set-up allows in many cases the {gamma}{prime} phase volume fraction to be measured with a good accuracy.

  13. Surface topography evolution of Ni-based single crystal superalloy under laser shock: Formation of the nano-scale surface reliefs

    NASA Astrophysics Data System (ADS)

    Lu, G. X.; Liu, J. D.; Qiao, H. C.; Zhou, Y. Z.; Jin, T.; Sun, X. F.; Hu, Z. Q.

    2017-03-01

    The aim of the study was to investigate the effect of laser shock peening (LSP) on surface topography evolution of metallic targets. Samples manufactured by a Ni-based single crystal superalloy with polished finish were treated by LSP, and the surface topographies before and after LSP were examined by non-contact White-Light Interferometer (WLI). Results showed the following three aspects: (a) By taking advantage of WLI, the shrinkage porosities and the interdendritic structures were observed simultaneously. (b) With the increasing impact times, the round pit induced by laser shock became deeper. (c) The nano-scale surface reliefs were found on the bottom of round pit induced by LSP, and the specific plastic flow of metallic materials under the action of compressive stresses was deemed as the primary contributor to the formation of surface reliefs. It revealed a novel microscale plastic deformation phenomenon of metallic materials in surface strengthening.

  14. Low-temperature magnetothermal transport investigation of a Ni-based superconductor BaNi2As2: evidence for fully gapped superconductivity.

    PubMed

    Kurita, N; Ronning, F; Tokiwa, Y; Bauer, E D; Subedi, A; Singh, D J; Thompson, J D; Movshovich, R

    2009-04-10

    We have performed low-temperature specific heat and thermal conductivity measurements of the Ni-based superconductor BaNi2As2 (T{c}=0.7 K) in a magnetic field. In a zero field, thermal conductivity shows T-linear behavior in the normal state and exhibits a BCS-like exponential decrease below T{c}. The field dependence of the residual thermal conductivity extrapolated to zero temperature is indicative of a fully gapped superconductor. This conclusion is supported by the analysis of the specific heat data, which are well fit by the BCS temperature dependence from T{c} down to the lowest temperature of 0.1 K.

  15. The effect of grain boundary on the dissolution of base metal into insert metal during TLP bonding of Ni-base superalloys

    NASA Astrophysics Data System (ADS)

    Kim, Dae-Up; Kang, Chung-Yun; Lee, Won-Jae

    1999-10-01

    The dissolution of base metal into insert metal during TLP bonding of Ni base CMSX-2 superalloys, was studied. The effect of grain size on the dissolution phenomenon was also investigated. TLP bonding of single crystal, coarse grained and fine grained CMSX-2 specimens was carried out at 1373-1548 K for 019.6 ks under 2.3 MPa. During TLP bonding, the dissolution of the base metal into insert metal occurred very rapidly, leading to constant dissolution width at a given holding time. The dissolution width of the base metal broadened with increasing bonding temperature and holding time in all samples used. The dissolution of the base metal into the insert melt pool was governed by Nernst-Brunner's theory in any grain size of base metal. The saturation time for dissolving base metal shortened, but its width broadened with increasing bonding temperature. The dissolution rate of the base metal increased with decreasing grain size of the base metals.

  16. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2002-01-01

    Seawater and natural brines accounted for about 60% of US magnesium compounds production in 2001. Dead-burned and caustic-calcined magnesias were recovered from seawater in Florida by Premier Chemicals. They were also recovered from Michigan well brines by Dow Chemical, Martin Marietta Magnesia Specialties and Rohm & Haas. And Premier Chemicals recovered dead-burned and caustic-calcined magnesias from magnesite in Nevada. Reilly Industries and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah.

  17. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2011-01-01

    Seawater and natural brines accounted for about 54 percent of U.S. magnesium compounds production in 2010. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash-Wendover and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its operation mentioned above.

  18. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2010-01-01

    Seawater and natural brines accounted for about 40 percent of U.S. magnesium compounds production in 2009. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Chemicals in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover, and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta from its operation mentioned above.

  19. Synthesis and Characterization of Sterically Hindered Alkylaluminum-Phosphorus and -Arsenic Compounds. X-Ray Crystal Structures of (Me3ECH2)3Al E’(SiMe3)3 (E = Si, E’ = As; E = C, E’ = P, As), (Me3SiCH2)2(Br)Al P(SiMe3)3, and (Me3SiCH2)(X)AlE(SiMe3)22 (X = Br, E = P, As; X = Me3SiCH2, E =As)

    DTIC Science & Technology

    2007-11-02

    Various physical and spectroscopic data, including a variable temperature NMR study of the dimeric compounds 6 through 9, are presented for the above...CHARACTERIZATION OF STERICALLY HINDERED ALKYLALUMINUM-PHOSPHORUS AND -ARSENIC COMPOUNDS . X-RAY CRYSTAL STRUCTURES OF (Me3ECH2)3Al«E’(SiMe3)3 (E = Si, E...Accepted for publication in the Organometallics 12a. DISTRIBUTION /AVAILABILITY STATEMENT Approved for Public Release Distribution Unlimited 12b

  20. The Radical SAM Enzyme HydG Requires Cysteine and a Dangler Iron for Generating an Organometallic Precursor to the [FeFe]-Hydrogenase H-Cluster.

    PubMed

    Suess, Daniel L M; Pham, Cindy C; Bürstel, Ingmar; Swartz, James R; Cramer, Stephen P; Britt, R David

    2016-02-03

    Three maturase enzymes-HydE, HydF, and HydG-synthesize and insert the organometallic component of the [FeFe]-hydrogenase active site (the H-cluster). HydG generates the first organometallic intermediates in this process, ultimately producing an [Fe(CO)2(CN)] complex. A limitation in understanding the mechanism by which this complex forms has been uncertainty regarding the precise metallocluster composition of HydG that comprises active enzyme. We herein show that the HydG auxiliary cluster must bind both l-cysteine and a dangler Fe in order to generate the [Fe(CO)2(CN)] product. These findings support a mechanistic framework in which a [(Cys)Fe(CO)2(CN)](-) species is a key intermediate in H-cluster maturation.

  1. The Radical SAM Enzyme HydG Requires Cysteine and a Dangler Iron for Generating an Organometallic Precursor to the [FeFe]-Hydrogenase H-Cluster

    PubMed Central

    Suess, Daniel L. M.; Pham, Cindy C.; Bürstel, Ingmar; Swartz, James R.; Cramer, Stephen P.; Britt, R. David

    2016-01-01

    Three maturase enzymes—HydE, HydF, and HydG—synthesize and insert the organometallic component of the [FeFe]-hydrogenase active site (the H-cluster). HydG generates the first organometallic intermediates in this process, ultimately producing an [Fe(CO)2(CN)] complex. A limitation in understanding the mechanism by which this complex forms has been uncertainty regarding the precise metallocluster composition of HydG that comprises active enzyme. We herein show that the HydG auxiliary cluster must bind both l-cysteine and a dangler Fe in order to generate the [Fe(CO)2(CN)] product. These findings support a mechanistic framework in which a [(Cys)Fe(CO)2(CN)]− species is a key intermediate in H-cluster maturation. PMID:26764535

  2. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2007-01-01

    Seawater and natural brines accounted for about 52 percent of U.S. magnesium compounds production in 2006. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from sea-water by Premier Chemicals in Florida; from well brines in Michigan by Martin Marietta and Rohm and Haas; and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from brucite by Applied Chemical Magnesias in Texas, from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta and Rohm and Haas from their operations mentioned above. About 59 percent of the magnesium compounds consumed in the United States was used for refractories that are used mainly to line steelmaking furnaces. The remaining 41 percent was consumed in agricultural, chemical, construction, environmental and industrial applications.

  3. Intermetallic Compounds

    NASA Astrophysics Data System (ADS)

    Takagiwa, Y.; Matsuura, Y.; Kimura, K.

    2014-06-01

    We have focused on the binary narrow-bandgap intermetallic compounds FeGa3 and RuGa3 as thermoelectric materials. Their crystal structure is FeGa3-type (tetragonal, P42/ mnm) with 16 atoms per unit cell. Despite their simple crystal structure, their room temperature thermal conductivity is in the range 4-5-W-m-1-K-1. Both compounds have narrow-bandgaps of approximately 0.3-eV near the Fermi level. Because their Seebeck coefficients are quite large negative values in the range 350-<-| S 373K|-<-550- μV-K-1 for undoped samples, it should be possible to obtain highly efficient thermoelectric materials both by adjusting the carrier concentration and by reducing the thermal conductivity. Here, we report the effects of doping on the thermoelectric properties of FeGa3 and RuGa3 as n and p-type materials. The dimensionless figure of merit, ZT, was significantly improved by substitution of Sn for Ga in FeGa3 (electron-doping) and by substitution of Zn for Ga in RuGa3 (hole-doping), mainly as a result of optimization of the electronic part, S 2 σ.

  4. Inhibition of the p53/hDM2 protein-protein interaction by cyclometallated iridium(III) compounds

    PubMed Central

    Liu, Li-Juan; He, Bingyong; Miles, Jennifer A.; Wang, Wanhe; Mao, Zhifeng; Che, Weng Ian; Lu, Jin-Jian; Chen, Xiu-Ping; Wilson, Andrew J.; Ma, Dik-Lung; Leung, Chung-Hang

    2016-01-01

    Inactivation of the p53 transcription factor by mutation or other mechanisms is a frequent event in tumorigenesis. One of the major endogenous negative regulators of p53 in humans is hDM2, a ubiquitin E3 ligase that binds to p53 causing proteasomal p53 degradation. In this work, a library of organometallic iridium(III) compounds were synthesized and evaluated for their ability to disrupt the p53/hDM2 protein-protein interaction. The novel cyclometallated iridium(III) compound 1 [Ir(eppy)2(dcphen)](PF6) (where eppy = 2-(4-ethylphenyl)pyridine and dcphen = 4, 7-dichloro-1, 10-phenanthroline) blocked the interaction of p53/hDM2 in human amelanotic melanoma cells. Finally, 1 exhibited anti-proliferative activity and induced apoptosis in cancer cell lines consistent with inhibition of the p53/hDM2 interaction. Compound 1 represents the first reported organometallic p53/hDM2 protein-protein interaction inhibitor. PMID:26883110

  5. Domain Walls Conductivity in Hybrid Organometallic Perovskites and Their Essential Role in CH3NH3PbI3 Solar Cell High Performance

    PubMed Central

    Rashkeev, Sergey N.; El-Mellouhi, Fedwa; Kais, Sabre; Alharbi, Fahhad H.

    2015-01-01

    The past several years has witnessed a surge of interest in organometallic trihalide perovskites, which are at the heart of the new generation of solid-state solar cells. Here, we calculated the static conductivity of charged domain walls in n- and p- doped organometallic uniaxial ferroelectric semiconductor perovskite CH3NH3PbI3 using the Landau-Ginzburg-Devonshire (LGD) theory. We find that due to the charge carrier accumulation, the static conductivity may drastically increase at the domain wall by 3 – 4 orders of magnitude in comparison with conductivity through the bulk of the material. Also, a two-dimensional degenerated gas of highly mobile charge carriers could be formed at the wall. The high values of conductivity at domain walls and interfaces explain high efficiency in organometallic solution-processed perovskite films which contains lots of different point and extended defects. These results could suggest new routes to enhance the performance of this promising class of novel photovoltaic materials. PMID:26088321

  6. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2012-01-01

    Seawater and natural brines accounted for about 57 percent of magnesium compounds produced in the United States in 2011. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties LLC from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia LLC in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash Wendover LLC and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma Inc. in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its brine operation in Michigan.

  7. Bismaleimide compounds

    DOEpatents

    Adams, Johnnie E.; Jamieson, Donald R.

    1986-01-14

    Bismaleimides of the formula ##STR1## wherein R.sub.1 and R.sub.2 each independently is H, C.sub.1-4 -alkyl, C.sub.1-4 -alkoxy, C1 or Br, or R.sub.1 and R.sub.2 together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R.sub.1 and R.sub.2 are not t-butyl or t-butoxy; X is O, S or Se; n is 1-3; and the alkylene bridging group, optionally, is substituted by 1-3 methyl groups or by fluorine, form polybismaleimide resins which have valuable physical properties. Uniquely, these compounds permit extended cure times, i.e., they remain fluid for a time sufficient to permit the formation of a homogeneous melt prior to curing.

  8. Bismaleimide compounds

    DOEpatents

    Adams, J.E.; Jamieson, D.R.

    1986-01-14

    Bismaleimides of the formula shown in the diagram wherein R[sub 1] and R[sub 2] each independently is H, C[sub 1-4]-alkyl, C[sub 1-4]-alkoxy, Cl or Br, or R[sub 1] and R[sub 2] together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R[sub 1] and R[sub 2] are not t-butyl or t-butoxy; X is O, S or Se; n is 1--3; and the alkylene bridging group, optionally, is substituted by 1--3 methyl groups or by fluorine, form polybismaleimide resins which have valuable physical properties. Uniquely, these compounds permit extended cure times, i.e., they remain fluid for a time sufficient to permit the formation of a homogeneous melt prior to curing.

  9. Characterization of a versatile organometallic pro-drug (CORM) for experimental CO based therapeutics

    PubMed Central

    Seixas, João D.; Mukhopadhyay, Abhik; Santos-Silva, Teresa; Otterbein, Leo E; Gallo, David J.; Rodrigues, Sandra S.; Guerreiro, Bruno H.; Gonçalves, Ana M. L.; Penacho, Nuno; Marques, Ana R.; Coelho, Ana C.; Reis, Patrícia M.; Romão, Maria J.; Romão, Carlos C.

    2013-01-01

    The complex fac-[Mo(CO)3(histidinate)]Na has been reported to be an effective CO− Releasing Molecule in vivo, eliciting therapeutic effects in several animal models of disease. The CO releasing profile of this complex in different settings both in vitro and in vivo reveals that the compound can readily liberate all of its three CO equivalents under biological conditions. The compound has low toxicity and cytoxicity and is not hemolytic. CO release is accompanied by a decrease in arterial blood pressure following administration in vivo. We studied its behavior in solution and upon the interaction with proteins. Reactive oxygen species (ROS) generation upon exposure to air and polyoxomolybdate formation in soaks with lysozyme crystals were observed as processes ensuing from the decomposition of the complex and the release of CO. PMID:23223860

  10. Shape, electronic structure and steric effects of organometallic nanocatalysts: relevant tools to improve the synergy between theory and experiment.

    PubMed

    Cusinato, Lucy; Del Rosal, Iker; Poteau, Romuald

    2017-01-03

    Working closely with experimentalists on the comprehension of the surface properties of catalytically active organometallic nanoparticles (NPs) requires the development of several computational strategies which significantly differ from the cluster domain where a precise knowledge of their optimal geometry is a mandatory prerequisite to computational modeling. Theoretical simulations can address several properties of organometallic nanoparticles: the morphology of the metal core, the surface composition under realistic thermodynamic conditions, the relationship between adsorption energies and predictive descriptors of reactivity. It is in such context that an integrated package has been developed or adapted in our group: (i) one tool aims at building a wide variety of the typical shapes exhibited by nanoparticles. Using Reverse Monte Carlo modeling, a given shape can be optimized in order to fit pair distribution function data obtained from X-ray diffraction measurements; (ii) trends in density functional theory (DFT) adsorption energies of surface species can be rationalized and predicted by making use of simple descriptors. This is why we have proposed an extension of the d-band center model, that leads to the formulation of a generalized ligand-field theory. A comparison between cobalt and ruthenium is proposed in the case of a 55-atoms nanocluster. The accuracy of the generalized coordination number [Angew. Chem., Int. Ed., 2014, 53, 8316], a very simple coordination-activity criterion, is also assessed; (iii) the builder package is completed by the steric-driven grafting of ligands on the surface of metal NPs. It easily generates structures with adjustable surface composition values and coordination modes; (iv) after a local optimization at the DFT level of theory, DFT energies and normal modes of vibration can feed a general tool based on the ab initio thermodynamics method. This method aims at easily calculating an optimal surface composition under realistic

  11. Organometallic Chemistry of Carbon Dioxide. Final Report for June 1, 1986 - March 31, 2002

    SciTech Connect

    Gibson, D. H.

    2002-09-26

    Research focused on C{sub 1} transition metal complexes that are relevant to CO{sub 2} activation and fixation. First, we prepared and studied new metallocarboxylic acids, a class of compounds proposed as intermediates in the Water Gas Shift reaction and CO{sub 2} reductions, and the corresponding metallocarboxylate anions. Next, we prepared and structurally characterized a large number of CO{sub 2}-bridged bimetallic compounds (models for metal surface-bound CO{sub 2}) and established structure-spectra correlations for the three general types of compounds identified. The next phase involved the synthesis and studies of putative catalytic intermediates derived from rhenium and ruthenium polypyridyl complexes in order to establish their fundamental reaction characteristics. Finally, we progressed to the design of a possible catalytic sequence which could account for C{sub 2} products formed in ruthenium-catalyzed CO{sub 2} reductions and to the synthesis, characterization and studies of the reactions of expected intermediates in the catalytic sequence.

  12. 10 000-hr Cyclic Oxidation Behavior of 68 High-Temperature Co-, Fe-, and Ni- Base Alloys Evaluated at 982 deg. C (1800 deg. F)

    NASA Technical Reports Server (NTRS)

    Barrett, Charles A.

    1999-01-01

    Power systems with operating temperatures in the range of 815 to 982 C (1500 to 1800 F) frequently require alloys that can operate for long times at these temperatures. A critical requirement is that these alloys have adequate oxidation resistance. The alloys used in these power systems require thousands of hours of operating life with intermittent shutdown to room temperature. Intermittent power plant shutdowns, however, offer the possibility that the protective scale will tend to spall (i.e., crack and flake off) upon cooling, increasing the rate of oxidative attack in subsequent heating cycles. Thus, it is critical that candidate alloys be evaluated for cyclic oxidation behavior. It was determined that exposing test alloys to ten 1000-hr cycles in static air at 982 10 000-hr Cyclic Oxidation Behavior of 68 High-Temperature Co-, Fe-, and Ni-Base Alloys Evaluated at 982 C (1800 F) could give a reasonable simulation of long-time power plant operation. Iron- (Fe-), nickel- (Ni-), and cobalt- (Co-) based high-temperature alloys with sufficient chromium (Cr) and/or aluminum (Al) content can exhibit excellent oxidation resistance. The protective oxides formed by these classes of alloys are typically Cr2O3 and/or Al2O3, and are usually influenced by their Cr, or Cr and Al, content. Sixty-eight Co-, Fe-, and Ni-base high-temperature alloys, typical of those used at this temperature or higher, were used in this study. At the NASA Lewis Research Center, the alloys were tested and compared on the basis of their weight change as a function of time, x-ray diffraction of the protective scale composition, and the physical appearance of the exposed samples. Although final appearance and x-ray diffraction of the final scale products were two factors used to evaluate the oxidation resistance of each alloy, the main criterion was the oxidation kinetics inferred from the specific weight change versus time data. These data indicated a range of oxidation behavior including parabolic

  13. Alumina-supported bimetallics of palladium alloyed with germanium, tin, lead, or antimony from organometallic precursors I. Preparation and characterization

    SciTech Connect

    Aduriz, H.R.; Bodnariuk, P. , Bahia Blanca ); Coq, B.; Figueras, F. )

    1989-09-01

    Bimetallic PdSn, PdSb, PdPb, and PdGe on alumina catalysts with a low metal content have been prepared using either chloride or organometallic precursors. For the catalysts obtained from chloride precursors no interaction was observed between the two metals, and the catalysts behaved like pure Pd/Al{sub 2}O{sub 3}. In contrast, the reactions of (C{sub 4}H{sub 9}){sub 4}Sn, (C{sub 4}H{sub 9}){sub 4}Pb, (C{sub 4}H{sub 9}){sub 4}Ge, or (C{sub 4}H{sub 9}){sub 3}Sb in n-heptane solution with reduced Pd/Al{sub 2}O{sub 3} catalyst yielded a supported alloy. The interaction between metallic palladium and the organic modifier is highly selective and leads to the formation of a well-tailored bimetallic catalyst. When these final solids are reduced at 573 or 773 K, the second metal locates preferentially at the outer layer of the bimetallic aggregates. After reduction at 773 K large metallic aggregates are obtained (particle size 15 nm), and the formation of {beta}-palladium hydride, which can be formed with pure palladium catalysts, is suppressed by the addition of a small amount of the second metal. The specific activity of the palladium surface atoms for isoprene hydrogenation is then lowered, and the selectivity increased.

  14. Design and synthesis of novel organometallic dyes for NiO sensitization and photo-electrochemical applications.

    PubMed

    Massin, Julien; Lyu, Siliu; Pavone, Michele; Muñoz-García, Ana B; Kauffmann, Brice; Toupance, Thierry; Chavarot-Kerlidou, Murielle; Artero, Vincent; Olivier, Céline

    2016-08-02

    Two metallo-organic dyes were synthesized and used for NiO sensitization in view of their photoelectrochemical applications. The new dyes present an original π-conjugated structure containing the [Ru(dppe)2] metal fragment with a highly delocalized allenylidene ligand on one side and a σ-alkynyl ligand bearing an electron-rich group, i.e. a thiophene or triphenylamine unit, and one or two anchoring functions on the other side. The optoelectronic, electrochemical and photoelectrochemical properties of the dyes were systematically investigated. A broad photoresponse was observed with the absorption maximum at 600 nm. The X-ray crystal structure of one precursor was obtained to elucidate the structural conformation of the organometallic complexes and theoretical calculations were performed in order to address the photophysical properties of the new dyes. These photosensitizers were further implemented in NiO-based photocathodes and tested as photocurrent generators under pertinent aqueous conditions in association with [Co(NH3)5Cl]Cl2 as an irreversible electron acceptor. The dye-sensitized photocathodes provided good photocurrent densities (40 to 60 μA cm(-2)) at neutral pH in phosphate buffer and a high stability was observed for the two dyes.

  15. Organometallic enantiomeric scaffolding: a strategy for the enantiocontrolled construction of regio- and stereodivergent trisubstituted piperidines from a common precursor.

    PubMed

    Wong, Heilam; Garnier-Amblard, Ethel C; Liebeskind, Lanny S

    2011-05-18

    Reported herein is a general and efficient method to construct 2,3,6-trisubstituted piperidines in a substituent-independent fashion. From the high enantiopurity organometallic scaffold (-)-Tp(CO)(2)[(η-2,3,4)-(1S,2S)-1-benzyloxycarbonyl-5-oxo-5,6-dihydro-2H-pyridin-2-yl)molybdenum (Tp = hydridotrispyrazolylborato), a variety of TpMo(CO)(2)-based 2,3,6-trifunctionalized complexes of the (η-3,4,5-dihydropyridinyl) ligand were easily obtained in 5 steps through a sequence of highly regio- and stereospecific metal-influenced transformations (15 examples). From the 2,3,6-trifunctionalized molybdenum complexes, either 2,6-cis-3-trans or 2,3,6-cis systems were selectively obtained through the choice of an appropriate stereodivergent demetalation protocol. The potential of this strategy in synthetic chemistry was demonstrated by the short total synthesis of four natural and one non-natural alkaloids: indolizidines (±)-209I and (±)-8-epi-219F in the racemic series, and enantiocontrolled syntheses of (-)-indolizidine 251N, (-)-quinolizidine 251AA, and (-)-dehydroindolizidine 233E.

  16. Behavior of DNAPL mixture of organometallic and chlorinated solvent in the presence of surfactants and alcohols as density modifying agents.

    PubMed

    Talawat, Jaruwan; Sabatini, David A; Tongcumpou, Chantra

    2013-01-01

    This work evaluates the behavior of surfactant and alcohols in combination with a mixture of tributyltinchloride (TBT) and tetrachloroethylene (PCE) with the goal of modifying the mixed oil from being a dense non-aqueous phase liquid (DNAPL) to a light non-aqueous phase liquid (LNAPL). Phase behavior of the mixed oil was studied under various combinations of surfactant, alcohol, and salinity. Phase density conversion was examined using pseudo-ternary phase diagrams constructed between the mixed oil, surfactant solution (4 wt%), and two types of alcohols (n-butyl alcohol (BuOH) and tert-butyl alcohol (TBA)). Aqueous phase solubilization and oil phase density modification were studied at varying alcohol to surfactant (A/S) ratios. The results showed that the optimum surfactant system was sodium dihexylsulfosuccinate (SDHS) and hexadecyl diphenyloxidedisulfonate (C16DPDS) (3.6 wt% and 0.4 wt%, respectively) with salt (NaCl) of 3 wt%. From pseudo-ternary phase diagrams, BuOH was found to produce a larger LNAPL region than TBA. From solubilization studies, the surfactant system plus either TBA or BuOH caused PCE preferential solubilization and this preference was more pronounced at higher total surfactant concentration in the system with TBA addition. In terms of density modification, BuOH produced lower oil density than TBA at high A/S ratio. This phase behavior knowledge can be used to optimize site remediation of organometallic DNAPLs.

  17. Computational design of organometallic oligomers featuring 1,3-metal-carbon bonding and planar tetracoordinate carbon atoms.

    PubMed

    Zhao, Xue-Feng; Yuan, Cai-Xia; Wang, Xiang; Li, Jia-Jia; Wu, Yan-Bo; Wang, Xiaotai

    2016-01-15

    Density functional theory computations (B3LYP) have been used to explore the chemistry of titanium-aromatic carbon "edge complexes" with 1,3-metal-carbon (1,3-MC) bonding between Ti and planar tetracoordinate Cβ . The titanium-coordinated, end-capping chlorides are replaced with OH or SH groups to afford two series of difunctional monomers that can undergo condensation to form oxide- and sulfide-bridged oligomers. The sulfide-linked oligomers have less molecular strain and are more exergonic than the corresponding oxide-linked oligomers. The HOMO-LUMO gap of the oligomers varies with their composition and decreases with growing oligomer chain. This theoretical study is intended to enrich 1,3-MC bonding and planar tetracoordinate carbon chemistry and provide interesting ideas to experimentalists. Organometallic complexes with the TiE2 (E = OH and SH) decoration on the edge of aromatic hydrocarbons have been computationally designed, which feature 1,3-metal-carbon (1,3-MC) bonding between titanium and planar tetracoordinate β-carbon. Condensation of these difunctional monomers by eliminating small molecules (H2O and H2S) produce chain-like oligomers. The HOMO-LUMO gaps of the oligomers decreases with growing oligomer chain, a trend that suggests possible semiconductor properties for oligomers with longer chains.

  18. Organometallic approach to polymer-protected antibacterial silver nanoparticles: optimal nanoparticle size-selection for bacteria interaction

    NASA Astrophysics Data System (ADS)

    Crespo, Julian; García-Barrasa, Jorge; López-de-Luzuriaga, José M.; Monge, Miguel; Olmos, M. Elena; Sáenz, Yolanda; Torres, Carmen

    2012-12-01

    The optimal size-specific affinity of silver nanoparticles (Ag NPs) towards E. coli bacteria has been studied. For this purpose, Ag NPs coated with polyvinylpyrrolidone (PVP) and cellulose acetate (CA) have been prepared using an organometallic approach. The complex NBu4[Ag(C6F5)2] has been treated with AgClO4 in a 1:1 molar ratio giving rise to the nanoparticle precursor [Ag(C6F5)] in solution. Addition of an excess of PVP ( 1) or CA ( 2) and 5 h of reflux in tetrahydrofuran (THF) at 66 °C leads to Ag NPs of small size (4.8 ± 3.0 nm for PVP-Ag NPs and 3.0 ± 1.2 nm for CA-Ag NPs) that coexist in both cases with larger nanoparticles between 7 and 25 nm. Both nanomaterials display a high antibacterial effectiveness against E. coli. The TEM analysis of the nanoparticle-bacterial cell membrane interaction shows an optimal size-specific affinity for PVP-Ag NPs of 5.4 ± 0.7 nm in the presence of larger size silver nanoparticles.

  19. Cytotoxicity of iron oxide nanoparticles made from the thermal decomposition of organometallics and aqueous phase transfer with Pluronic F127

    PubMed Central

    Gonzales, Marcela; Mitsumori, Lee M.; Kushleika, John V.; Rosenfeld, Michael E.; Krishnan, Kannan M.

    2010-01-01

    Magnetic nanoparticles are promising molecular imaging agents due to their relative high relaxivity and the potential to modify surface functionality to tailor biodistribution. In this work we describe the synthesis of magnetic nanoparticles using organic solvents with organometallic precursors. This method results in nanoparticles that are highly crystalline, and have uniform size and shape. The ability to create a monodispersion of particles of the same size and shape results in unique magnetic properties that can be useful for biomedical applications with MR imaging. Before these nanoparticles can be used in biological applications, however, means are needed to make the nanoparticles soluble in aqueous solutions and the toxicity of these nanoparticles needs to be studied. We have developed two methods to surface modify and transfer these nanoparticles to the aqueous phase using the biocompatible co-polymer, Pluronic F127. Cytotoxicity was found to be dependent on the coating procedure used. Nanoparticle effects on a cell-culture model was quantified using concurrent assaying; a LDH assay to determine cytotoxicity and an MTS assay to determine viability for a 24 hour incubation period. Concurrent assaying was done to insure that nanoparticles did not interfere with the colorimetric assay results. This report demonstrates that a monodispersion of nanoparticles of uniform size and shape can be manufactured. Initial cytotoxicity testing of new molecular imaging agents need to be carefully constructed to avoid interference and erroneous results. PMID:20623517

  20. Organometallic Enantiomeric Scaffolding. A Strategy for the Enantiocontrolled Construction of Regio- and Stereodivergent Trisubstituted Piperidines from a Common Precursor

    PubMed Central

    Wong, Heilam; Garnier-Amblard, Ethel C.; Liebeskind, Lanny S.

    2011-01-01

    Reported herein is a general and efficient method to construct 2,3,6-trisubstituted piperidines in a substituent-independent fashion. From the high enantiopurity organometallic scaffold (−)-Tp(CO)2[(η-2,3,4)-(1S, 2S)-1-benzyloxycarbonyl-5-oxo-5,6-dihydro-2H-pyridin-2-yl)molybdenum (Tp = hydridotrispyrazolylborato), a variety of TpMo(CO)2-based 2,3,6-trifunctionalized complexes of the (η-3,4,5-dihydropyridinyl) ligand were easily obtained in 5 steps through a sequence of highly regio- and stereospecific metal-influenced transformations (15 examples). From the 2,3,6-trifunctionalized molybdenum complexes, either 2,6-cis-3-trans or 2,3,6-cis systems were selectively obtained through the choice of an appropriate stereodivergent demetalation protocol. The potential of this strategy in synthetic chemistry was demonstrated by the short total synthesis of four natural and one non-natural alkaloids: indolizidines (±)-209I and (±)-8-epi-219F in the racemic series, and enantiocontrolled syntheses of (−)-indolizidine 251N, (−)-quinolizidine 251AA, and (−)-dehydroindolizidine 233E. PMID:21513336

  1. Effects of prehafnizing on morphological development of a chemical vapor deposition aluminide coating formed on single-crystal Ni-based superalloy

    NASA Astrophysics Data System (ADS)

    He, L. M.; Meyer, J. D.; Lee, W. Y.

    2004-03-01

    We examined a sequential Hf doping procedure, which consisted of (1) “prehafnizing” the surface of a single-crystal Ni-based superalloy (RENÉ N5) with HfCl4 and H2, and (2) aluminizing with AlCl3 and H2, as a means of incorporating Hf as a dopant in the aluminide coating matrix. The prehafnized layer on RENÉ N5 substrate significantly altered the growth behavior and therefore the morphology of the resulting aluminide coating. With the prehafnizing step, the coating layer became much thinner with a significant amount of Hf incorporated as Hf-rich phases (Hf2Ni7, Hf3Ni7, and/or Hf8Ni21). However, the Hf-rich phases segregated to the coating surface and retarded the inward Al diffusion required to form the β-NiAl coating matrix. The sequential Hf doping procedure provided a mechanism to incorporate a significant amount of Hf in the coating, but did not produce a uniform distribution of Hf as a dopant. The results were compared to those observed for a continuous doping procedure that was previously studied, and were discussed in the context of understanding the limitations of these procedures.

  2. Crack Progression during Sustained-Peak Low-Cycle Fatigue in Single-Crystal Ni-Base Superalloy René N5

    NASA Astrophysics Data System (ADS)

    Suzuki, A.; Gigliotti, M. F. X.; Hazel, B. T.; Konitzer, D. G.; Pollock, T. M.

    2010-04-01

    Crack progression during compressive sustained-peak low-cycle fatigue (SPLCF) was examined in vapor phase aluminide coated single-crystal Ni-base superalloy René N5. Strain-controlled tests with a 120-second hold at compression were conducted at 1366 K (1093 °C) with A = -1 ( R = -∞) and 0.35 pct total strain range, and were terminated at selected fractions of predicted life. Crack lengths on the surface and crack depth in longitudinal sections were examined for each specimen. All cracks appeared to have initiated at the coating surface. Failed specimens showed that cracks initially grew on (001), perpendicular to the stress axis, and then deflected to other crystallographic planes. Interrupted test specimens showed crevices initiated on the coating surface at less than 10 pct of the predicted life. The depths of crevices into the coating increased with cyclic exposure, but they did not penetrate into the substrate through the interdiffusion zone (IDZ) until about 80 pct of predicted life. Stress relaxation during compressive hold results in residual tension upon unloading. These results suggest that improving creep resistance of the substrate alloy and developing a coating system that can delay crack penetration into the substrate are keys for improved SPLCF life.

  3. Surface Tension and Viscosity of the Ni-Based Superalloys LEK94 and CMSX-10 Measured by the Oscillating Drop Method on Board a Parabolic Flight

    NASA Astrophysics Data System (ADS)

    Wunderlich, Rainer K.; Fecht, Hans-Jörg; Lohöfer, Georg

    2017-02-01

    The surface tension and viscosity of the Ni-based superalloys LEK94 and CMSX-10 were measured by the oscillating drop method in a containerless electromagnetic processing device on board a parabolic flight airplane. Surface oscillations were recorded by 150 and 200 Hz frame rate digital cameras positioned in two perpendicular directions and by the inductive coupling between the oscillating sample surface and the oscillating circuit of the radio frequency heating and positioning generator. The surface tension as a function of temperature of LEK94 and CMSX-10 was obtained as σ( T) = 1.73 - 4.51 × 10-4 [ T—1656 K (1383 °C)] Nm-1 and σ( T) = 1.71 - 5.80 × 10-4 [( T—1683 K (1410 °C)] Nm-1, respectively. The viscosity at the liquidus temperatures as 9.8 and 7.8 mPa.s, respectively. In addition, some basic thermophysical properties such as solidus and liquidus temperatures, densities at room temperature, and thermal expansion in the solid phase are reported.

  4. Temperature dependence of the intrinsic small fatigue crack growth behavior in ni-base superalloys based on measurement of crack closure

    NASA Astrophysics Data System (ADS)

    Okazaki, M.; Yamada, H.; Nohmi, S.

    1996-04-01

    The effect of temperature on the small fatigue crack growth behavior of a single crystal and directionally solidified Ni-base superalloys was investigated at temperatures between 873 to 1123 K by measuring the crack closure. The results were also compared with those of the physically long crack. It was found that the propagation resistance and the fatigue threshold of the long cracks increased with temperature in all the materials. The long crack growth rates at three temperatures were approximately represented by an unique curve, after taking account of crack closure level and elastic modulus. In contrast, the small crack growth resistance decreased with temperature even when the crack closure phenomenon was taken into consideration. Furthermore, the small fatigue cracks exhibited considerably higher growth rates than the long cracks at a given effective stress intensity factor range and also grew under effective stress intensity factor ranges below the long crack threshold. The factors responsible for the lack of similitude in propagation rates between small and long cracks were also discussed, based on these observations and the chemical analysis near the crack tip using the electron probe microanalyzer.

  5. Effect of Primary Dendrite Orientation on Stray Grain Formation in Cross-Section Change Region During the Directional Solidification of Ni-Based Superalloy

    NASA Astrophysics Data System (ADS)

    Xuan, Weidong; Li, Chuantao; Zhao, Dengke; Wang, Baojun; Li, Chuanjun; Ren, Zhongming; Zhong, Yunbo; Li, Xi; Cao, Guanghui

    2017-02-01

    The effect of primary dendrite orientation on stray grain formation in a cross-section change region during the directional solidification of Ni-based superalloy is investigated through both experimental observations and numerical simulation. The results clearly show that the orientation of primary dendrite affects the formation of stray grains in the cross-section change region. It is observed that, for the primary dendrite without misorientation, no stray grain is formed in the cross-section change region; for the primary dendrite with a moderate misorientation (15 deg), stray grains are formed only on the side converging from the mold wall in the cross-section change region. When the misorientation is 25 deg, stray grains are formed on both the side converging from the mold wall and the side diverging from the mold wall in the cross-section change region (the converging side and the diverging side for short). The simulation results are in accordance with experimental results. Furthermore, the correlation among factors such as stray grain formation, primary dendrite orientation, and withdrawal velocity has been analyzed. The mechanism of stray grain formation in various oriented primary dendrites is discussed.

  6. The Wyckoff positional order and polyhedral intergrowth in the M3B2- and M5B3-type boride precipitated in the Ni-based superalloys

    PubMed Central

    Hu, X. B.; Zhu, Y. L.; Sheng, N. C.; Ma, X. L.

    2014-01-01

    Ni-based single superalloys play a crucial role in the hottest parts of jet engines. However, due to the complex geometry and macro-segregation during the solidification process, the cast defect such as stray grains is inevitable. Therefore, the transient liquid phase (TLP) bonding which can join several small single crystalline castings together is gradually believed to be an effective method for improving the yields of production of the complex components. The melting point depressant element B is always added into the interlayer filler material. Consequently, borides including the M3B2 and M5B3 phase usually precipitate during the TLP bonding process. So a comprehensive knowledge of the fine structural characteristics of the borides is very critical for an accurate evaluation of the TLP bonding process. In this work, by means of the aberration-corrected transmission electron microscopy, we show, at an atomic scale, the Wyckoff positional order phenomenon of the metal atoms in the unit cell of M3B2- and M5B3-type boride. Meanwhile, the defect along the (001) plane of the above two types of boride are determined to be the polyhedral intergrowth with complex configurations. PMID:25482386

  7. Microstructure and Mechanical Properties of Dissimilar Welded Ti3Al/Ni-Based Superalloy Joint Using a Ni-Cu Filler Alloy

    NASA Astrophysics Data System (ADS)

    Chen, Bing-Qing; Xiong, Hua-Ping; Guo, Shao-Qing; Sun, Bing-Bing; Chen, Bo; Tang, Si-Yi

    2015-02-01

    Dissimilar welding of a Ti3Al-based alloy and a Ni-based superalloy (Inconel 718) was successfully carried out using gas tungsten arc welding technology in this study. With a Ni-Cu alloy as filler material, sound joints have been obtained. The microstructure evolution along the cross section of the dissimilar joint has been revealed based on the results of scanning electron microscopy and X-ray energy dispersive spectroscopy as well as X-ray diffractometer. It is found that the weld/Ti3Al interface is composed of Ti2AlNb matrix dissolved with Ni and Cu, Al(Cu, Ni)2Ti, (Cu, Ni)2Ti, (Nb, Ti) solid solution, and so on. The weld and In718/weld interface mainly consist of (Cu, Ni) solid solutions. The weld exhibits higher microhardness than the two base materials. The average room-temperature tensile strength of the joints reaches 242 MPa and up to 73.6 pct of the value can be maintained at 873 K (600 °C). The brittle intermetallic phase of Ti2AlNb matrix dissolved with Ni and Cu at the weld/Ti3Al interface is the weak link of the joint.

  8. Initial assessment of Ni-base alloy performance in 0.1 MPa and supercritical CO2

    SciTech Connect

    Pint, B. A.; Keiser, J. R.

    2015-09-25

    There is considerable interest in increasing the working temperature of both open and closed supercritical CO2 (sCO2) cycles to ≥700 °C. At these temperatures, it is unlikely that any Fe-base alloys have suitable strength and therefore the focus is on Ni-base alloys for this application. To begin addressing the lack of compatibility data under these conditions, initial work exposed a wide range of candidate alloys in 500-h exposures at 20 MPa (200 bar) CO2 at 650 -750 °C in high purity CO2. In general, the reaction products were thin and protective in these exposures. A smaller group of alloy coupons focusing on chromia- and alumina-forming alloys was exposed for 500h in 0.1 MPa (1bar) air, CO2, CO2+O2 and CO2+H2O for comparison. Thus, the thin surface oxides formed were very similar to those formed at high pressure and no clear detrimental effect of CO2 oxidation or O2 or H2O impurities could be observed in these exposures.

  9. The Wyckoff positional order and polyhedral intergrowth in the M3B2- and M5B3-type boride precipitated in the Ni-based superalloys

    NASA Astrophysics Data System (ADS)

    Hu, X. B.; Zhu, Y. L.; Sheng, N. C.; Ma, X. L.

    2014-12-01

    Ni-based single superalloys play a crucial role in the hottest parts of jet engines. However, due to the complex geometry and macro-segregation during the solidification process, the cast defect such as stray grains is inevitable. Therefore, the transient liquid phase (TLP) bonding which can join several small single crystalline castings together is gradually believed to be an effective method for improving the yields of production of the complex components. The melting point depressant element B is always added into the interlayer filler material. Consequently, borides including the M3B2 and M5B3 phase usually precipitate during the TLP bonding process. So a comprehensive knowledge of the fine structural characteristics of the borides is very critical for an accurate evaluation of the TLP bonding process. In this work, by means of the aberration-corrected transmission electron microscopy, we show, at an atomic scale, the Wyckoff positional order phenomenon of the metal atoms in the unit cell of M3B2- and M5B3-type boride. Meanwhile, the defect along the (001) plane of the above two types of boride are determined to be the polyhedral intergrowth with complex configurations.

  10. Application of indium tin oxide (ITO) thin film as a low emissivity film on Ni-based alloy at high temperature

    NASA Astrophysics Data System (ADS)

    Sun, Kewei; Zhou, Wancheng; Tang, Xiufeng; Luo, Fa

    2016-09-01

    Indium tin oxide (ITO) films as the low emissivity coatings of Ni-based alloy at high temperature were studies. ITO films were deposited on the polished surface of alloy K424 by direct current magnetron sputtering. These ITO-coated samples were heat-treated in air at 600-900 °C for 150 h to explore the effect of high temperature environment on the emissivity. The samples were analyzed by X-ray diffraction (XRD), SEM and EDS. The results show that the surface of sample is integrity after heat processing at 700 °C and below it. A small amount of fine crack is observed on the surface of sample heated at 800 °C and Ti oxide appears. There are lots of fine cracks on the sample annealed at 900 °C and a large number of various oxides are detected. The average infrared emissivities at 3-5 μm and 8-14 μm wavebands were tested by an infrared emissivity measurement instrument. The results show the emissivity of the sample after annealed at 600 and 700 °C is still kept at a low value as the sample before annealed. The ITO film can be used as a low emissivity coating of super alloy K424 up to 700 °C.

  11. Effects of alloying elements and temperature on the elastic properties of dilute Ni-base superalloys from first-principles calculations

    NASA Astrophysics Data System (ADS)

    Shang, S. L.; Kim, D. E.; Zacherl, C. L.; Wang, Y.; Du, Y.; Liu, Z. K.

    2012-09-01

    The variation of elastic properties, e.g., elastic constants, bulk modulus, and shear modulus of dilute Ni-base superalloys due to alloying elements (X's) and temperature, has been studied via first-principles calculations. Here, 26 alloying elements are considered: Al, Co, Cr, Cu, Fe, Hf, Ir, Mn, Mo, Nb, Os, Pd, Pt, Re, Rh, Ru, Sc, Si, Ta, Tc, Ti, V, W, Y, Zn, and Zr. It is found that (i) both the bulk and shear moduli of Ni-X decrease approximately linearly with increasing equilibrium volume, especially within each group of 3d, 4d, or 5d transition-metal alloying elements; (ii) all alloying elements considered herein increase the ratio of bulk to shear modulus (i.e., the ductility) and the elastic anisotropy of the Ni-X alloys; and (iii) the largest decrease of elastic properties of Ni is caused by alloying element Y. It is observed that the change of elastic properties of Ni due to various alloying elements is traceable from the distribution of (magnetization) charge density, for instance the spherical distribution of charge density facilitates shear deformation, resulting in a lower shear-related property. Using a proposed quasistatic approach based on the predicted elasticity-volume-temperature relationship, the isothermal and the isentropic elastic properties are predicted for the dilute Ni-X alloys at finite temperatures, displaying a decreasing trend with respect to temperature for each Ni-X system. Computed elastic properties are in favorable accord with available experimental data.

  12. Single-Molecule Conductance Studies of Organometallic Complexes Bearing 3-Thienyl Contacting Groups.

    PubMed

    Bock, Sören; Al-Owaedi, Oday A; Eaves, Samantha G; Milan, David C; Lemmer, Mario; Skelton, Brian W; Osorio, Henrry M; Nichols, Richard J; Higgins, Simon J; Cea, Pilar; Long, Nicholas J; Albrecht, Tim; Martín, Santiago; Lambert, Colin J; Low, Paul J

    2017-02-10

    The compounds and complexes 1,4-C6 H4 (C≡C-cyclo-3-C4 H3 S)2 (2), trans-[Pt(C≡C-cyclo-3-C4 H3 S)2 (PEt3 )2 ] (3), trans-[Ru(C≡C-cyclo-3-C4 H3 S)2 (dppe)2 ] (4; dppe=1,2-bis(diphenylphosphino)ethane) and trans-[Ru(C≡C-cyclo-3-C4 H3 S)2 {P(OEt)3 }4 ] (5) featuring the 3-thienyl moiety as a surface contacting group for gold electrodes have been prepared, crystallographically characterised in the case of 3-5 and studied in metal|molecule|metal junctions by using both scanning tunnelling microscope break-junction (STM-BJ) and STM-I(s) methods (measuring the tunnelling current (I) as a function of distance (s)). The compounds exhibit similar conductance profiles, with a low conductance feature being more readily identified by STM-I(s) methods, and a higher feature by the STM-BJ method. The lower conductance feature was further characterised by analysis using an unsupervised, automated multi-parameter vector classification (MPVC) of the conductance traces. The combination of similarly structured HOMOs and non-resonant tunnelling mechanism accounts for the remarkably similar conductance values across the chemically distinct members of the family 2-5.

  13. Stereoselective Alkane Oxidation with meta-Chloroperoxybenzoic Acid (MCPBA) Catalyzed by Organometallic Cobalt Complexes.

    PubMed

    Shul'pin, Georgiy B; Loginov, Dmitriy A; Shul'pina, Lidia S; Ikonnikov, Nikolay S; Idrisov, Vladislav O; Vinogradov, Mikhail M; Osipov, Sergey N; Nelyubina, Yulia V; Tyubaeva, Polina M

    2016-11-22

    Cobalt pi-complexes, previously described in the literature and specially synthesized and characterized in this work, were used as catalysts in homogeneous oxidation of organic compounds with peroxides. These complexes contain pi-butadienyl and pi-cyclopentadienyl ligands: [(tetramethylcyclobutadiene)(benzene)cobalt] hexafluorophosphate, [(C₄Me₄)Co(C₆H₆)]PF₆ (1); diiodo(carbonyl)(pentamethylcyclopentadienyl)cobalt, Cp*Co(CO)I₂ (2); diiodo(carbonyl)(cyclopentadienyl)cobalt, CpCo(CO)I₂ (3); (tetramethylcyclobutadiene)(dicarbonyl)(iodo)cobalt, (C₄Me₄)Co(CO)₂I (4); [(tetramethylcyclobutadiene)(acetonitrile)(2,2'-bipyridyl)cobalt] hexafluorophosphate, [(C₄Me₄)Co(bipy)(MeCN)]PF₆ (5); bis[dicarbonyl(B-cyclohexylborole)]cobalt, [(C₄H₄BCy)Co(CO)₂]₂ (6); [(pentamethylcyclopentadienyl)(iodo)(1,10-phenanthroline)cobalt] hexafluorophosphate, [Cp*Co(phen)I]PF₆ (7); diiodo(cyclopentadienyl)cobalt, [CpCoI₂]₂ (8); [(cyclopentadienyl)(iodo)(2,2'-bipyridyl)cobalt] hexafluorophosphate, [CpCo(bipy)I]PF₆ (9); and [(pentamethylcyclopentadienyl)(iodo)(2,2'-bipyridyl)cobalt] hexafluorophosphate, [Cp*Co(bipy)I]PF₆ (10). Complexes 1 and 2 catalyze very efficient and stereoselective oxygenation of tertiary C-H bonds in isomeric dimethylcyclohexanes with MCBA: cyclohexanols are produced in 39 and 53% yields and with the trans/cis ratio (of isomers with mutual trans- or cis-configuration of two methyl groups) 0.05 and 0.06, respectively. Addition of nitric acid as co-catalyst dramatically enhances both the yield of oxygenates and stereoselectivity parameter. In contrast to compounds 1 and 2, complexes 9 and 10 turned out to be very poor catalysts (the yields of oxygenates in the reaction with cis-1,2-dimethylcyclohexane were only 5%-7% and trans/cis ratio 0.8 indicated that the oxidation is not stereoselective). The chromatograms of the reaction mixture obtained before and after reduction with PPh₃ are very similar, which testifies that alkyl

  14. Discovery of a highly tumor-selective organometallic ruthenium(II)-arene complex.

    PubMed

    Clavel, Catherine M; Păunescu, Emilia; Nowak-Sliwinska, Patrycja; Griffioen, Arjan W; Scopelliti, Rosario; Dyson, Paul J

    2014-04-24

    A ruthenium(II)-arene complex with a perfluoroalkyl-ligand was found to display remarkable selectivity toward cancer cells. IC50 values on several cancer cell lines are in the range of 25-45 μM, and no cytotoxic effect was observed on nontumorigenic (HEK-293) cells at concentrations up to 500 μM (the maximum concentration tested). Consequently, this complex was used as the basis for the development of a number of related derivatives, which were screened in cancerous and noncancerous cell lines. The lead compound was then evaluated in vivo for antiangiogenic activity in the CAM model and in a xenografted ovarian carcinoma tumor (A2780) grown on the CAM. A 90% reduction in the tumor growth was observed.

  15. Emission and fs/ns-TRANSIENT Absorption of Organometallic Complexes Bound to a Dinuclear Metal Center

    NASA Astrophysics Data System (ADS)

    Durr, Christopher B.; Brown-Xu, Samantha E.; Chisholm, Malcolm H.

    2012-06-01

    Compounds containing a MM quadruple bond (M = Mo or W) of the form M2L2L'2, where L and L' are conjugated organic ligands, show interesting photophysical properties along with a metal-to-ligand charge transfer (MLCT) band that is tunable throughout the UV-Vis-NIR spectra. Recently, our attention has shifted towards ligands that incorporate a secondary transition metal complex bound to an organic moiety. Along with allowing for a second tunable MLCT band for better coverage of the solar spectrum, these hybrid molecules show unique spectroscopic properties that were explored using fs/ns-transient absorption and UV-Vis/NIR emission. These techniques allow for the elucidation of the electronic character of the excited states as well as their lifetimes. This knowledge will be put to use in the design of new materials that could later be incorporated into next generation photovoltaic devices.

  16. Spontaneous Double Hydrometallation Induced by N→M Coordination in Organometallic Hydrides of Group 14 Elements.

    PubMed

    Novák, Miroslav; Dostál, Libor; Turek, Jan; Alonso, Mercedes; De Proft, Frank; Růžička, Aleš; Jambor, Roman

    2016-04-11

    Our attempts to synthesise N→M intramolecularly coordinated diorganometallic hydrides L2MH2 [M=Si (4), Ge (5), Sn (6)] containing the CH=N imine group (in which L is C,N-chelating ligand {2-[(2,6-iPr2C6H3)N=CH]C6 H4}(-)) yielded 1,1'-bis(2,6-diisopropylphenyl)-2,2'-spriobi[benzo[c][1,2]azasilole] (7), 1,1'-bis(2,6-diisopropylphenyl)-2,2'-spriobi[benzo[c][1,2]azagermole] (8) and C,N-chelated homoleptic stannylene L2Sn (10), respectively. Compounds 7 and 8 are an outcome of a spontaneous double hydrometallation of the two CH=N imine moieties induced by N→M intramolecular coordination (M=Si, Ge) in the absence of any catalyst. In contrast, the diorganotin hydride L2SnH2 (6) is redox-unstable and the reduction of the tin centre with the elimination of H2 provided the C,N-chelated homoleptic stannylene L2Sn (10). Compounds 7 and 8 were characterised by NMR spectroscopy and X-ray diffraction analysis. Because the proposed N→M intramolecularly coordinated diorganometallic hydrides L2MH2 [M=Si (4), Ge (5), Sn (6)] revealed two different types of reduction reactions, DFT calculations were performed to gain an insight into the structures and bonding of the non-isolable diorganometallic hydrides as well as the products of their subsequent reactions. Furthermore, the thermodynamic profiles of the different reaction pathways with respect to the central metal atom were also investigated.

  17. Hybrid organometallic compounds of gallium: UV excimer laser photochemistry of Ga( t-C 4H 9) n(CH 3) 3- n ( n = 0, 1, 2, 3)

    NASA Astrophysics Data System (ADS)

    Cleaver, W. M.; Barron, A. R.; Zhang, Y.; Stuke, M.

    1992-01-01

    The gas-phase ultraviolet (UV) excimer laser induced photolysis of the gallium-alkyls Ga( t-C 4H 9) n(CH 3) 3- n ( n = 0, 1, 2, 3) was studied, using photolysis wavelenghts of 308, 248 and 193 nm. The photofragments Ga, GaH and GaCH 3 were detected by laser ionization time-of-flight mass spectroscopy, while the hydrocarbon products CH 4, C 2H 6, HC(CH 3) 3 and H 2C=C(CH 3) 2 were identified using Fourier transform infrared (FTIR) spectroscopy. The formation of the GaH photofragment, and a high olefin-to-alkane product ratio, for Ga( t-C 4H 9) 2(CH 3) and Ga( t-C 4H 9) 3 is interpreted to indicate a β-hydrogen elimination process. However, β-hydrogen elimination only occurs after fission of the weakest Ga-C bond, thus no β-hydride elimination is observed for Ga( t-C 4H 9)(CH 3) 2.

  18. The influence of a presence of a heavy atom on the spin-spin coupling constants between two light nuclei in organometallic compounds and halogen derivatives

    SciTech Connect

    Wodyński, Artur; Pecul, Magdalena

    2014-01-14

    The {sup 1}J{sub CC} and {sup 1}J{sub CH} spin-spin coupling constants have been calculated by means of density functional theory (DFT) for a set of derivatives of aliphatic hydrocarbons substituted with I, At, Cd, and Hg in order to evaluate the substituent and relativistic effects for these properties. The main goal was to estimate HALA (heavy-atom-on-light-atom) effects on spin-spin coupling constants and to explore the factors which may influence the HALA effect on these properties, including the nature of the heavy atom substituent and carbon hybridization. The methods applied range, in order of reduced complexity, from Dirac-Kohn-Sham method (density functional theory with four-component Dirac-Coulomb Hamiltonian), through DFT with two- and one-component Zeroth Order Regular Approximation (ZORA) Hamiltonians, to scalar non-relativistic effective core potentials with the non-relativistic Hamiltonian. Thus, we are able to compare the performance of ZORA-DFT and Dirac-Kohn-Sham methods for modelling of the HALA effects on the spin-spin coupling constants.

  19. The influence of a presence of a heavy atom on the spin-spin coupling constants between two light nuclei in organometallic compounds and halogen derivatives

    NASA Astrophysics Data System (ADS)

    Wodyński, Artur; Pecul, Magdalena

    2014-01-01

    The 1JCC and 1JCH spin-spin coupling constants have been calculated by means of density functional theory (DFT) for a set of derivatives of aliphatic hydrocarbons substituted with I, At, Cd, and Hg in order to evaluate the substituent and relativistic effects for these properties. The main goal was to estimate HALA (heavy-atom-on-light-atom) effects on spin-spin coupling constants and to explore the factors which may influence the HALA effect on these properties, including the nature of the heavy atom substituent and carbon hybridization. The methods applied range, in order of reduced complexity, from Dirac-Kohn-Sham method (density functional theory with four-component Dirac-Coulomb Hamiltonian), through DFT with two- and one-component Zeroth Order Regular Approximation (ZORA) Hamiltonians, to scalar non-relativistic effective core potentials with the non-relativistic Hamiltonian. Thus, we are able to compare the performance of ZORA-DFT and Dirac-Kohn-Sham methods for modelling of the HALA effects on the spin-spin coupling constants.

  20. Organometallic Modeling of the Hydrodesulfurization (HDS) Process: Rhenium Carbonyl-promoted C-S Bond Cleavage and Hydrogenation of Thiophenes and Benozothiophenes

    SciTech Connect

    Reynolds, Michael A.

    2000-09-21

    Organometallic modeling of the HDS process at single or multiple metal centers is one approach to better understanding the mechanism that govern commercial HDS. Therefore, we have currently been investigating the use of Re2(CO)10 as a potential model system for catalytic HDS with respect to S-binding, ring-opening, and hydrogenation of thiophenes andbenzothiophenes. We have also been investigating the use of UV-light as a method for activating thiophenic molecules towards C-S and C-H bond cleavage.