Sample records for complexes synthesis reactivity

  1. Synthesis, Structure and Reactivity of Lanthanocene Complexes

    Institute of Scientific and Technical Information of China (English)

    QIAN, Chang-Tao(钱长涛); ZHU, Cheng-Jian(朱成建)


    A variety of lanthanocene complexes,e.g.chlorides,hydrocarbyls,amides,hydrides and divalent derivatives,were synthesized by using a series of destgned cyclopentadienyl,indenyl and fluorenyl ligands with ring bridges or dornor-functionalized sidearms.X-Ray crystallographic analyses reveal the formation of intramolecular coordination bonds between central metals and heteroatoms(O,N)in sidearms or bridging chains.Some applications of these complexes are also discussed in this account.

  2. Synthesis, characterization, and reactivity of pentamethylcyclopentadienyl complexes of divalent cobalt and nickel

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Michael Edward [Univ. of California, Berkeley, CA (United States)


    The thesis is divided into the following 4 chapters: synthesis, characterization, and reactivity of trinuclear pentamethylcyclopentadienyl cobalt and nickel clusters with triply-bridging methylidyne groups; chemical and physical properties of pentamethylcyclopentadienyl acetylacetonate complexes of Co(II) and Ni(II); synthesis, characterization, and reactivity of pentamethylcyclopentadienyl halide complexes of Co and Ni; and crystallographic studies of distortions in metallocenes with C5-symmetrical cyclopentadienyl rings.

  3. Synthesis, characterization, and reactivity of pentamethylcyclopentadienyl complexes of divalent cobalt and nickel

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.E.


    The thesis is divided into the following 4 chapters: synthesis, characterization, and reactivity of trinuclear pentamethylcyclopentadienyl cobalt and nickel clusters with triply-bridging methylidyne groups; chemical and physical properties of pentamethylcyclopentadienyl acetylacetonate complexes of Co(II) and Ni(II); synthesis, characterization, and reactivity of pentamethylcyclopentadienyl halide complexes of Co and Ni; and crystallographic studies of distortions in metallocenes with C{sub 5}-symmetrical cyclopentadienyl rings.

  4. Unprecedented copper(I) bifluoride complexes: synthesis, characterization and reactivity. (United States)

    Vergote, Thomas; Nahra, Fady; Welle, Alexandre; Luhmer, Michel; Wouters, Johan; Mager, Nathalie; Riant, Olivier; Leyssens, Tom


    To be or not to bifluoride: Two synthetic pathways to unprecedented N-heterocyclic carbene copper(I) bifluoride complexes have been developed. Catalytic tests demonstrated that copper(I) bifluorides are very efficient catalysts, which do not require any additional activating agent. The first Cu-catalyzed diastereoselective allylation of (R)-N-tert-butanesulfinyl aldimines was also established. The method enables efficient, simple and general synthesis of enantiomerically enriched homoallylic amines at room temperature in high yields.

  5. Synthesis and Reactivity of Ruthenium Phosphite Indenylidene Complexes


    Bantreil, Xavier; Poater, Albert; Urbina-Blanco, César A; Bidal, Yannick D.; Falivene, Laura; Randall, Rebecca A. M.; Cavallo, Luigi; Slawin, Alexandra M. Z.; Cazin, Catherine S. J.


    The synthesis of the four olefin metathesis precatalysts Caz-1a-d, featuring the NHC ligand N,N'-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene (SIMes) and four different phosphites (P((OPr)-Pr-i)(3), P(OPh)(3), P(OEt)(3), and P(OMe)(3)), is reported. The complexes are readily synthesized from commercially available [RuCl2(3-phenylinden-1-ylidene)-(pyridine)(SIMes)] (Ind-III) in yields of up to 88%. These complexes adopt an unusual cis configuration between the phosphite and the NHC ligands. ...

  6. Synthesis and Reactivity of Tripodal Complexes Containing Pendant Bases

    Energy Technology Data Exchange (ETDEWEB)

    Blacquiere, Johanna M.; Pegis, Michael L.; Raugei, Simone; Kaminsky, Werner; Forget, Amelie; Cook, Sarah; Taguchi, Taketo; Borovik, Andrew S.; Mayer, James M.


    The synthesis of a new tripodal ligand family is reported, with tertiary-amine groups in the second-coordination sphere. The ligands are tris(amido)amine derivatives, with the pendant amines attached via a peptide coupling strategy. They were designed to be used in new catalysts for the oxygen reduction reaction (ORR), in which the pendant acid/base group could improve catalyst performance. Two members of the new ligand family were each metallated with Co(II) and Zn(II) to afford trigonal monopyramidal complexes. Reaction of the cobalt complexes, [Co(L)]-, with dioxygen reversibly generates a small amount of a Co(III)-superoxo species, which was characterized by EPR. Protonation of the zinc complex Zn[N{CH2CH2NC(O)CH2N(CH2Ph)2}3)-– ([Zn(TNBn)]-) with one equivalent of acid occurs with displacement and dissociation of an amide ligand. Addition of excess acid to the any of the complexes [M(L)]- results in complete proteolysis and formation of the ligands H3L. This decomposition limits the use of these complexes as catalysts for the ORR. An alternative ligand with two pyridyl arms was also prepared but could not be metallated. These studies highlight the importance of stability of the primary-coordination sphere of ORR electrocatalysts to both oxidative and acidic conditions. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.

  7. Pentamethylcyclopentadienyl Zirconium and Hafnium Polyhydride Complexes : Synthesis, Structure, and Reactivity

    NARCIS (Netherlands)

    Visser, Cindy; Hende, Johannes R. van den; Meetsma, Auke; Hessen, Bart; Teuben, Jan H.


    The half-sandwich zirconium and hafnium N,N-dimethylaminopropyl complexes Cp*M[(CH2)3NMe2]Cl2 (Cp* = η5-C5Me5, M = Zr, 1; Hf, 2) and Cp*M[(CH2)3NMe2]2Cl (M = Zr, 3; Hf, 4) were synthesized by mono- or dialkylation of Cp*MCl3 with the corresponding alkyllithium and Grignard reagents. Hydrogenolysis

  8. Unsaturated platinum-rhenium cluster complexes. Synthesis, structures and reactivity. (United States)

    Adams, Richard D; Captain, Burjor; Smith, Mark D; Beddie, Chad; Hall, Michael B


    Two new compounds PtRe3(CO)12(PBut3)(micro-H)3, 9, and PtRe2(CO)9(PBut3)(micro-H)2, 10, were obtained from the reaction of Pt(PBut3)2 with Re3(CO)12(micro-H3), 8, at room temperature. Compound 9 contains a butterfly cluster of four metals formed by the insertion of the platinum atom from a Pt(PBut3) group into one of the hydride-bridged metal-metal bonds of 8. The three hydrido ligands are bridging ligands across each of three new Pt-Re bonds. Compound 10 contains a triangular PtRe2 cluster with two hydrido ligands; one bridges a Pt-Re bond, and the other bridges the Re-Re bond. The new compound Pt2Re2(CO)7(PBut3)2(micro-H)2, 11, was obtained from the reaction of 8 with Pt(PBut3)2 in hexane at reflux. Compound 11 was also obtained from 10 by reaction with an additional quantity of Pt(PBut3)2. Compound 11 contains a tetrahedral cluster of four metal atoms with two dynamically active hydrido ligands. A CO ligand on one of the two platinum atoms also exchanges between the two platinum atoms rapidly on the NMR time scale. Compound 11 is electronically unsaturated and was found to add hydrogen at room temperature to form the tetrahydrido cluster complex, Pt2Re2(CO)7(PBut3)2(micro-H)4, 12. Compound 12 has a structure similar to 11 but contains one triply bridging hydrido ligand, two edge bridging hydrido ligands, and one terminal hydrido ligand on one of the two platinum atoms. A kinetic isotope effect D/H of 1.5(1) was determined for the addition of H2 to 11. Hydrogen can be eliminated from 12 by heating to 97 degrees C or by the application of UV-vis irradiation at room temperature. Compound 12 adds CO at room temperature to yield the complex Pt2Re2(CO)8(PBut3)2(micro-H)4, 13, which contains a planar cluster of four metal atoms with a Pt-Pt bond and four edge bridging hydrido ligands. Compounds 11 and 12 react with Pt(PBut3)2 to yield the known five metal cluster complexes Pt3Re2(CO)6(PBut3)3(micro-H)2, 14, and Pt3Re2(CO)6(PBut3)3(micro-H)4, 15, respectively. Density

  9. Synthesis and Reactivity of Metal Complexes in Trigonal N,O,O,O-Environments


    Adelhardt, Mario Erwin


    High-valent iron complexes, for instance stabilized by multiple bonded oxo, nitrido, or imido ligands, have been identified as reactive intermediates in biological as well as technical systems. Although numerous synthetic model complexes have been synthesized and characterized in the past four decades, they often lack the high reactivity of their parental compounds. One strategy to enhance the reactivity of, for example, Fe(IV) oxo complexes is to enforce a trigonal coordination geometry ar...

  10. Group 3 metal stilbene complexes: Synthesis, reactivity, and electronic structure studies


    Huang, W.; Abukhalil, PM; Khan, SI; Diaconescu, PL


    Group 3 metal (E)-stilbene complexes supported by a ferrocene diamide ligand were synthesized and characterized. Reactivity studies showed that they behave similar to analogous naphthalene complexes. Experimental and computational results indicated that the double bond was reduced and not a phenyl ring, in contrast to a previously reported uranium (E)-stilbene complex. © the Partner Organisations 2014.

  11. Synthesis, Structure, and Reactivity of Arylchlorobis(dialkyl sulfide)platinum(II) Complexes. (United States)

    Wendt, Ola F.; Oskarsson Å, Åke; Leipoldt, Johann G.; Elding, Lars I.


    Complexes trans-[PtRCl(SR'(2))(2)], where R = Ph, mesityl, and p-anisyl and R' = Me or Et, have been synthesized and their crystal and molecular structures determined. Crystals of trans-[PtPhCl(SEt(2))(2)] (2) are triclinic (P&onemacr;) with a = 10.112(6) Å, b = 13.158(2) Å, c = 14.714(5) Å, alpha = 102.48(2) degrees, beta = 94.394(4) degrees, gamma = 90.22(3) degrees, and Z = 4. Crystals of trans-[Pt(mesityl)Cl(SMe(2))(2)] (4) are monoclinic (P2(1)/c) with a = 13.158(2) Å, b = 9.170(1) Å, c = 16.013(3) Å, beta = 120.93(2) degrees, and Z = 4, and crystals of [Pt(p-anisyl)Cl(SMe(2))(2)] (5) are monoclinic (P2(1)/n) with a = 9.879(4) Å, b = 8.128(2) Å, c = 19.460(5) Å, beta = 96.56(3) degrees, and Z = 4. All complexes are square-planar, featuring Pt-Cl distances between 2.40 and 2.42 Å, indicating a large ground-state trans influence of the aryl group. The coordination geometry is maintained in methanol and chloroform solution as shown by (1)H-NMR spectra. The kinetics of substitution of the labile chloride trans to aryl by various nucleophiles has been studied in methanol by variable-temperature and -pressure stopped-flow spectrophotometry. A two-term rate law with a well-developed solvolytic pathway is followed. Negative entropies and volumes of activation indicate an associative mode of activation in all cases, independent of steric blocking of the axial sites and a large Pt-Cl ground-state bond-weakening. Comparison of the reaction rates of the present series of complexes with their bis(phosphine) analogues and with related cyclometalated compounds shows that the triethylphosphine complexes are 2-3 orders of magnitude less reactive than the thioether complexes, which in turn are a factor 10-20 less reactive than the cyclometalated ones. This reactivity increase can be rationalized mainly in terms of a decrease in steric hindrance in the series. There seems to be no inherent differences with regard to trans labilizing ability of the aryl ligands in the

  12. Synthesis, crystal structure and reactivity studies of iron complexes with pybox ligands

    KAUST Repository

    Chen, Tao


    Iron(II) complexes, [Fe(2,6-bis(4,4-dimethyl-1,3-oxazolin-2-yl)pyridine)Cl2] ((Fe(Me2-pybox)Cl2), 3) and [Fe(2,6-bis(4,4-diphenyl-1,3-oxazolin-2-yl)pyridine)Cl2] ((Fe(Ph2-pybox)Cl2), 4), have been synthesized and characterized by X-ray crystallographic analysis. Upon treatment of complex 3 with silver triflate and 4 with acetonitrile, [Fe(Me2-pybox)(CH3CN)OTf2] (5) and [Fe(Ph2-pybox)(CH3CN)2Cl][FeCl3] (6) were obtained, respectively. The bulkier phenyl substitutes were found not only to cause the elongation of the N-Fe bonds but also influence the reactivity of the Fe center.

  13. The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes (United States)

    Phanopoulos, Andreas; Long, Nicholas; Miller, Philip


    Herein we report the synthesis of a tridentate phosphine ligand N(CH2PPh2)3 (N-triphosPh) (1) via a phosphorus based Mannich reaction of the hydroxylmethylene phosphine precursor with ammonia in methanol under a nitrogen atmosphere. The N-triphosPh ligand precipitates from the solution after approximately 1 hr of reflux and can be isolated analytically pure via simple cannula filtration procedure under nitrogen. Reaction of the N-triphosPh ligand with [Ru3(CO)12] under reflux affords a deep red solution that show evolution of CO gas on ligand complexation. Orange crystals of the complex [Ru(CO)2{N(CH2PPh2)3}-κ3P] (2) were isolated on cooling to RT. The 31P{1H} NMR spectrum showed a characteristic single peak at lower frequency compared to the free ligand. Reaction of a toluene solution of complex 2 with oxygen resulted in the instantaneous precipitation of the carbonate complex [Ru(CO3)(CO){N(CH2PPh2)3}-κ3P] (3) as an air stable orange solid. Subsequent hydrogenation of 3 under 15 bar of hydrogen in a high-pressure reactor gave the dihydride complex [RuH2(CO){N(CH2PPh2)3}-κ3P] (4), which was fully characterized by X-ray crystallography and NMR spectroscopy. Complexes 3 and 4 are potentially useful catalyst precursors for a range of hydrogenation reactions, including biomass-derived products such as levulinic acid (LA). Complex 4 was found to cleanly react with LA in the presence of the proton source additive NH4PF6 to give [Ru(CO){N(CH2PPh2)3}-κ3P{CH3CO(CH2)2CO2H}-κ2O](PF6) (6). PMID:25938678

  14. Two-coordinate terminal zinc hydride complexes: synthesis, structure and preliminary reactivity studies. (United States)

    Dawkins, Michael J C; Middleton, Ewart; Kefalidis, Christos E; Dange, Deepak; Juckel, Martin M; Maron, Laurent; Jones, Cameron


    The first examples of essentially two-coordinate, monomeric zinc hydride complexes, LZnH (L = -N(Ar)(SiR3)) (Ar = C6H2{C(H)Ph2}2R'-2,6,4; R = Me, R' = Pr(i) (L'); R = Pr(i), R' = Me (L*); R = Pr(i), R' = Pr(i) (L(†))) have been prepared and shown by crystallographic studies to have near linear N-Zn-H fragments. The results of computational studies imply that any PhZn interactions in the compounds are weak at best. Preliminary reactivity studies reveal the compounds to be effective for the stoichiometric hydrozincation and catalytic hydrosilylation of carbonyl compounds.

  15. An Azobenzenyl Anion Radical Complex of Magnesium: Synthesis, Structure, and Reactivity Studies. (United States)

    Ren, Wenshan; Gu, Defa


    Azobenzenyl anion radical complex of magnesium [HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(PhNNPh) (THF) (2) was obtained for the first time through the reaction of [HC(C(Me)N-2,6-(i)Pr2C6H3)2]MgBr (1) with potassium graphite in the presence of azobenzene. Complex 2 is a useful electron-transfer reagent as shown by the reactivity with diphenyl disulfide, diphenyl diselenide, oxygen, sulfur, and Me3SiN3 yielding the magnesium thiolate [HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(SPh)(THF) (3), magnesium selenolate [HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(SePh)(THF) (4), peroxido complex {[HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(THF)}2(μ-η(2)-η(2)-O2) (5), persulfido complex {[HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(THF)}2(μ-η(2)-η(2)-S2) (6), and azido complex [HC(C(Me)N-2,6-(i)Pr2C6H3)2]MgN3 (7), respectively. Furthermore, treatment of 2 with Me3SiCHN2 results in a rearrangement product {[HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg[CNN(SiMe3)]}2 (8).

  16. Synthesis of mixed Cp/Tp(Me2) lanthanide complexes from lanthanocene precursors and their structures and reactivities. (United States)

    Han, Fuyan; Zhang, Jie; Han, Yanan; Zhang, Zhengxing; Chen, Zhenxia; Weng, Linhong; Zhou, Xigeng


    Reaction of Cp(2)LnCl with 1 equiv of KTp(Me2) in toluene gives the mixed Tp(Me2)/Cp lanthanide complexes Cp(2)Ln(Tp(Me2)) (Ln = Yb (1a), Er (1b), Dy (1c)), while unexpected complexes CpLn(Tp(Me2))Cl(THF) (Ln = Yb (2a), Er (2b.THF), Dy (2c), Y (2d)) are obtained when the reactions are carried out in THF. Complex 2b can also be formed by the reaction of CpErCl(2)(THF)(3) with 1 equiv of KTp(Me2) in THF. Moreover, complex 1a can also be obtained from the reaction of Cp(3)Yb and KTp(Me2). The results not only represent an efficient and versatile method for the synthesis of mixed Cp/Tp(Me2) lanthanide complexes but also provide new insight into the reactivity of Cp(2)LnCl. Furthermore, the reactivities of complexes 1a-c toward proton-donating reagents are examined. It has been found that 1b reacts with benzotriazole (C(6)H(4)NHN(2)) in THF to yield a lanthanide metallomacrocyclic complex [(Tp(Me2))CpEr(mu-N(3)C(6)H(4))](3) (3), while the reaction of 1a with 1 equiv of 2-aminopyridine in THF gives an unexpected oxide complex [(Tp(Me2))Yb(2-HNC(5)H(4)N)](2)(mu-O) (4). Presumably, the oxide ligand of compound 4 results from adventitious water. In addition, treatment of 1c with 2 equiv of 3,5-dimethylpyrazole yields a completely Cp-abstracted product (Tp(Me2))Dy(Pz(Me2))(2)(THF) (5), which can also be directly obtained from a three-component reaction of Cp(2)DyCl, KTp(Me2), and 3,5-dimethylpyrazole in THF. These results further indicate that the new mixed Tp(Me2)/Cp lanthanide complexes are practical and versatile precursors for the synthesis of poly(pyrazolyl)borate lanthanide derivatives. All new compounds have been characterized by elemental analysis and spectroscopic methods. The structures of complexes 1a,b and 2-5 have also been determined through single-crystal X-ray diffraction analysis.

  17. Bulky guanidinato nickel(I) complexes: synthesis, characterization, isomerization, and reactivity studies. (United States)

    Jones, Cameron; Schulten, Christian; Fohlmeister, Lea; Stasch, Andreas; Murray, Keith S; Moubaraki, Boujemaa; Kohl, Stuart; Ertem, Mehmed Z; Gagliardi, Laura; Cramer, Christopher J


    Reactions of lithium complexes of the bulky guanidinates [{(Dip)N}(2)CNR(2)](-) (Dip=C(6)H(3)iPr(2)-2,6; R=C(6)H(11) (Giso(-)) or iPr (Priso(-)), with NiBr(2) have afforded the nickel(II) complexes [{Ni(L)(μ-Br)}(2)] (L=Giso(-) or Priso(-)), the latter of which was crystallographically characterized. Reduction of [{Ni(Priso)(μ-Br)}(2)] with elemental potassium in benzene or toluene afforded the diamagnetic species [{Ni(Priso)}(2)(μ-C(6)H(5)R)] (R=H or Me), which were shown, by X-ray crystallographic studies, to possess nonplanar bridging arene ligands that are partially reduced. A similar reduction of [{Ni(Priso)(μ-Br)}(2)] in cyclohexane yielded a mixture of the isomeric complexes [{Ni(μ-κ(1)-N-,η(2)-Dip-Priso)}(2)] and [{Ni(μ-κ(2)-N,N'-Priso)}(2)], both of which were structurally characterized. These complexes were also formed through arene elimination processes if [{Ni(Priso)}(2)(μ-C(6)H(5)R)] (R=H or Me) were dissolved in hexane. In that solvent, diamagnetic [{Ni(μ-κ(1)-N-,η(2)-Dip-Priso)}(2)] was found to slowly convert to paramagnetic [{Ni(μ-κ(2)-N,N'-Priso)}(2)], suggesting that the latter is the thermodynamic isomer. Computational analysis of a model of [{Ni(μ-κ(2)-N,N'-Priso)}(2)] showed it to have a Ni-Ni bond that has a multiconfigurational electronic structure. An analogous copper(I) complex [{Cu(μ-κ(2)-N,N'-Giso)}(2)] was prepared, structurally authenticated, and found, by a theoretical study, to have a negligible Cu···Cu bonding interaction. The reactivity of [{Ni(Priso)}(2)(μ-C(6)H(5)Me)] and [{Ni(μ-κ(2)-N,N'-Priso)}(2)] towards a range of small molecules was examined and this gave rise to diamagnetic complexes [{Ni(Priso)(μ-CO)}(2)] and [{Ni(Priso)(μ-N(3))}(2)]. Taken as a whole, this study highlights similarities between bulky guanidinate ligands and the β-diketiminate ligand class, but shows the former to have greater coordinative flexibility.

  18. Synthesis, Structure, and Reactivity of Co(II) and Ni(II) PCP Pincer Borohydride Complexes. (United States)

    Murugesan, Sathiyamoorthy; Stöger, Berthold; Weil, Matthias; Veiros, Luis F; Kirchner, Karl


    The 15e square-planar complexes [Co(PCP(Me)-iPr)Cl] (2a) and [Co(PCP-tBu)Cl] (2b), respectively, react readily with NaBH4 to afford complexes [Co(PCP(Me)-iPr)(η(2)-BH4)] (4a) and [Co(PCP-tBu)(η(2)-BH4)] (4b) in high yields, as confirmed by IR spectroscopy, X-ray crystallography, and elemental analysis. The borohydride ligand is symmetrically bound to the cobalt center in η(2)-fashion. These compounds are paramagnetic with effective magnetic moments of 2.0(1) and 2.1(1) μB consistent with a d(7) low-spin system corresponding to one unpaired electron. None of these complexes reacted with CO2 to give formate complexes. For structural and reactivity comparisons, we prepared the analogous Ni(II) borohydride complex [Ni(PCP(Me)-iPr)(η(2)-BH4)] (5) via two different synthetic routes. One utilizes [Ni(PCP(Me)-iPr)Cl] (3) and NaBH4, the second one makes use of the hydride complex [Ni(PCP(Me)-iPr)H] (6) and BH3·THF. In both cases, 5 is obtained in high yields. In contrast to 4a and 4b, the borohydride ligand is asymmetrically bound to the nickel center but still in an η(2)-mode. [Ni(PCP(Me)-iPr)(η(2)-BH4)] (5) loses readily BH3 at elevated temperatures in the presence of NEt3 to form 6. Complexes 5 and 6 are both diamagnetic and were characterized by a combination of (1)H, (13)C{(1)H}, and (31)P{(1)H} NMR, IR spectroscopy, and elemental analysis. Additionally, the structure of these compounds was established by X-ray crystallography. Complexes 5 and 6 react with CO2 to give the formate complex [Ni(PCP(Me)-iPr)(OC(C=O)H] (7). The extrusion of BH3 from [Co(PCP(Me)-iPr)(η(2)-BH4)] (4a) and [Ni(PCP(Me)-iPr)(η(2)-BH4)] (5) with the aid of NH3 to yield the respective hydride complexes [Co(PCP(Me)-iPr)H] and [Ni(PCP(Me)-iPr)H] (6) and BH3NH3 was investigated by DFT calculations showing that formation of the Ni hydride is thermodynamically favorable, whereas the formation of the Co(II) hydride, in agreement with the experiment, is unfavorable. The electronic structures and

  19. Synthesis, Structure, and Reactivity of Co(II) and Ni(II) PCP Pincer Borohydride Complexes (United States)


    The 15e square-planar complexes [Co(PCPMe-iPr)Cl] (2a) and [Co(PCP-tBu)Cl] (2b), respectively, react readily with NaBH4 to afford complexes [Co(PCPMe-iPr)(η2-BH4)] (4a) and [Co(PCP-tBu)(η2-BH4)] (4b) in high yields, as confirmed by IR spectroscopy, X-ray crystallography, and elemental analysis. The borohydride ligand is symmetrically bound to the cobalt center in η2-fashion. These compounds are paramagnetic with effective magnetic moments of 2.0(1) and 2.1(1) μB consistent with a d7 low-spin system corresponding to one unpaired electron. None of these complexes reacted with CO2 to give formate complexes. For structural and reactivity comparisons, we prepared the analogous Ni(II) borohydride complex [Ni(PCPMe-iPr)(η2-BH4)] (5) via two different synthetic routes. One utilizes [Ni(PCPMe-iPr)Cl] (3) and NaBH4, the second one makes use of the hydride complex [Ni(PCPMe-iPr)H] (6) and BH3·THF. In both cases, 5 is obtained in high yields. In contrast to 4a and 4b, the borohydride ligand is asymmetrically bound to the nickel center but still in an η2-mode. [Ni(PCPMe-iPr)(η2-BH4)] (5) loses readily BH3 at elevated temperatures in the presence of NEt3 to form 6. Complexes 5 and 6 are both diamagnetic and were characterized by a combination of 1H, 13C{1H}, and 31P{1H} NMR, IR spectroscopy, and elemental analysis. Additionally, the structure of these compounds was established by X-ray crystallography. Complexes 5 and 6 react with CO2 to give the formate complex [Ni(PCPMe-iPr)(OC(C=O)H] (7). The extrusion of BH3 from [Co(PCPMe-iPr)(η2-BH4)] (4a) and [Ni(PCPMe-iPr)(η2-BH4)] (5) with the aid of NH3 to yield the respective hydride complexes [Co(PCPMe-iPr)H] and [Ni(PCPMe-iPr)H] (6) and BH3NH3 was investigated by DFT calculations showing that formation of the Ni hydride is thermodynamically favorable, whereas the formation of the Co(II) hydride, in agreement with the experiment, is unfavorable. The electronic structures and the bonding of the borohydride ligand in [Co

  20. Synthesis, characterization, and reactivities of manganese(V)-oxo porphyrin complexes. (United States)

    Song, Woon Ju; Seo, Mi Sook; George, Serena Debeer; Ohta, Takehiro; Song, Rita; Kang, Min-Jung; Tosha, Takehiko; Kitagawa, Teizo; Solomon, Edward I; Nam, Wonwoo


    The reactions of manganese(III) porphyrin complexes with terminal oxidants, such as m-chloroperbenzoic acid, iodosylarenes, and H(2)O(2), produced high-valent manganese(V)-oxo porphyrins in the presence of base in organic solvents at room temperature. The manganese(V)-oxo porphyrins have been characterized with various spectroscopic techniques, including UV-vis, EPR, 1H and 19F NMR, resonance Raman, and X-ray absorption spectroscopy. The combined spectroscopic results indicate that the manganese(V)-oxo porphyrins are diamagnetic low-spin (S = 0) species with a longer, weaker Mn-O bond than in previously reported Mn(V)-oxo complexes of non-porphyrin ligands. This is indicative of double-bond character between the manganese(V) ion and the oxygen atom and may be attributed to the presence of a trans axial ligand. The [(Porp)Mn(V)=O](+) species are stable in the presence of base at room temperature. The stability of the intermediates is dependent on base concentration. In the absence of base, (Porp)Mn(IV)=O is generated instead of the [(Porp)Mn(V)=O](+) species. The stability of the [(Porp)Mn(V)=O](+) species also depends on the electronic nature of the porphyrin ligands: [(Porp)Mn(V)=O](+) complexes bearing electron-deficient porphyrin ligands are more stable than those bearing electron-rich porphyrins. Reactivity studies of manganese(V)-oxo porphyrins revealed that the intermediates are capable of oxygenating PPh(3) and thioanisoles, but not olefins and alkanes at room temperature. These results indicate that the oxidizing power of [(Porp)Mn(V)=O](+) is low in the presence of base. However, when the [(Porp)Mn(V)=O](+) complexes were associated with iodosylbenzene in the presence of olefins and alkanes, high yields of oxygenated products were obtained in the catalytic olefin epoxidation and alkane hydroxylation reactions. Mechanistic aspects, such as oxygen exchange between [(Porp)Mn(V)=16O](+) and H(2)(18)O, are also discussed.

  1. Coinage Metal Hydrides: Synthesis, Characterization, and Reactivity. (United States)

    Jordan, Abraham J; Lalic, Gojko; Sadighi, Joseph P


    Hydride complexes of copper, silver, and gold encompass a broad array of structures, and their distinctive reactivity has enabled dramatic recent advances in synthesis and catalysis. This Review summarizes the synthesis, characterization, and key stoichiometric reactions of isolable or observable coinage metal hydrides. It discusses catalytic processes in which coinage metal hydrides are known or probable intermediates, and presents mechanistic studies of selected catalytic reactions. The purpose of this Review is to convey how developments in coinage metal hydride chemistry have led to new organic transformations, and how developments in catalysis have in turn inspired the synthesis of reactive new complexes.

  2. Cationic methyl complexes of the rare-earth metals: an experimental and computational study on synthesis, structure, and reactivity. (United States)

    Kramer, Mathias U; Robert, Dominique; Arndt, Stefan; Zeimentz, Peter M; Spaniol, Thomas P; Yahia, Ahmed; Maron, Laurent; Eisenstein, Odile; Okuda, Jun


    Synthesis, structure, and reactivity of two families of rare-earth metal complexes containing discrete methyl cations [LnMe(2-x)(thf)n]((1+x)+) (x = 0, 1; thf = tetrahydrofuran) have been studied. As a synthetic equivalent for the elusive trimethyl complex [LnMe3], lithium methylates of the approximate composition [Li3LnMe6(thf)n] were prepared by treating rare-earth metal trichlorides [LnCl3(thf)n] with 6 equiv of methyllithium in diethyl ether. Heteronuclear complexes of the formula [Li3Ln2Me9L(n)] (Ln = Sc, Y, Tb; L = Et2O, thf) were isolated by crystallization from diethyl ether. Single crystal X-ray diffraction studies revealed a heterometallic aggregate of composition [Li3Ln2Me9(thf)n(Et2O)m] with a [LiLn2Me9](2-) core (Ln = Sc, Y, Tb). When tris(tetramethylaluminate) [Ln(AlMe4)3] (Ln = Y, Lu) was reacted with less than 1 equiv of [NR3H][BPh4], the dimethyl cations [LnMe2(thf)n][BPh4] were obtained. The coordination number as well as cis/trans isomer preference was studied by crystallographic and computational methods. Dicationic methyl complexes of the rare-earth metals of the formula [LnMe(thf)n][BAr4]2 (Ln = Sc, Y, La-Nd, Sm, Gd-Lu; Ar = Ph, C6H4F-4) were synthesized, by protonolysis of either the ate complex [Li3LnMe6(thf)n] (Ln = Sc, Y, Gd-Lu) or the tris(tetramethylaluminate) [Ln(AlMe4)3] (Ln = La-Nd, Sm, Dy, Gd) with ammonium borates [NR3H][BAr4] in thf. The number of coordinated thf ligands varied from n = 5 (Ln = Sc, Tm) to n = 6 (Ln = La, Y, Sm, Dy, Ho). The configuration of representative examples was determined by X-ray diffraction studies and confirmed by density-functional theory calculations. The highly polarized bonding between the methyl group and the rare-earth metal center results in the reactivity pattern dominated by the carbanionic character and the pronounced Lewis acidity: The dicationic methyl complex [YMe(thf)6](2+) inserted benzophenone as an electrophile to give the alkoxy complex [Y(OCMePh2)(thf)5](2+). Nucleophilic addition of

  3. Synthesis, Structure, and Reactivity ofbis(1,2,4-tri-t-butylcyclopentadienyl) Complexes of Cerium

    Energy Technology Data Exchange (ETDEWEB)

    Werkema, Evan L. [Univ. of California, Berkeley, CA (United States)


    fluorobenzenes, permittingthe synthesis of specific Cp'2CeC6HxF5-x complexes. The crystal structureof Cp'2CeC6F5 is presented. The hydride and the metallacycle react withfluoromethanes, CH4-xFx, x = 1-3, through postulated Cp'2CeCH3-xFx intermediates to generate Cp'2CeF and other products. The other products,CH4, tri-t-butylbenzenes, tri-t-butylfluorobenzenes, and a presumedmetallocene cerium fluoride with one Cp' and one (Me2EtC)(Me3C)2C5H2 ligand, suggest a decomposition pathway for Cp'2CeCH3-xFx , x = 1-3, thatinvolves carbenes or carbenoids, which are trapped. The hydridepolymerizes ethylene, but hydrogenates other olefins. The metallacycleactivates C-H bonds in olefins and aromatics to generate new complexeswith Ce-C bonds. The hydride reacts with one equivalent of CO in pentaneto generate (Cp'2Ce)2CH2O, whose crystal structure shows the presence ofa bridging dianionic formaldehyde ligand. (Cp'2Ce)2&l

  4. Synthesis, structures, and reactivity of the base-stabilized silanone molybdenum complexes. (United States)

    Muraoka, Takako; Abe, Keisuke; Kimura, Haruhiko; Haga, Youhei; Ueno, Keiji; Sunada, Yusuke


    Base-stabilized silanone molybdenum complexes were synthesized by the oxygenation of the M=Si bond in the silyl(silylene)molybdenum complex with 1 eq. of PNO in the presence of Lewis base L. The PNO-coordinated silanone complex (L = PNO) was converted to cis-[Cp*(OC)2Mo{OSiMes2(OSiMe3)}(PMe3)] in the presence of excess PMe3.

  5. Synthesis, bonding, and reactivity of a cerium(IV) fluoride complex. (United States)

    Williams, Ursula J; Robinson, Jerome R; Lewis, Andrew J; Carroll, Patrick J; Walsh, Patrick J; Schelter, Eric J


    Oxidation of Ce[N(SiMe3)2]3 in the presence of PF6(-) or BF4(-) afforded isolation of CeF[N(SiMe3)2]3. Structural and electrochemical characterization shows that this compound is in its tetravalent oxidation state and contains a terminal fluoride ligand. Spectroscopy and density functional theory have been used to characterize the Ce-F bond as ionic, which is reinforced by an initial reactivity study that demonstrates the nucleophilicity of the fluoride ligand.

  6. Lead-chromium carbonyl complexes incorporated with group 8 metals: synthesis, reactivity, and theoretical calculations. (United States)

    Shieh, Minghuey; Chu, Yen-Yi; Hsu, Miao-Hsing; Ke, Wei-Ming; Lin, Chien-Nan


    The trichromium-lead complex [Pb{Cr(CO)5}3](2-) (1) was isolated from the reaction of PbCl2 and Cr(CO)6 in a KOH/MeOH solution, and the new mixed chromium-iron-lead complex [Pb{Cr(CO)5}{Fe(CO)4}2](2-) (3) was synthesized from the reaction of PbCl2 and Cr(CO)6 in a KOH/MeOH solution followed by the addition of Fe(CO)5. X-ray crystallography showed that 3 consisted of a central Pb atom bound in a trigonal-planar environment to two Fe(CO)4 and one Cr(CO)5 fragments. When complex 1 reacted with 1.5 equiv of Mn(CO)5Br, the Cr(CO)4-bridged dimeric lead-chromium carbonyl complex [Pb2Br2Cr4(CO)18](2-) (4) was produced. However, a similar reaction of 3 or the isostructural triiron-lead complex [Pb{Fe(CO)4}3](2-) (2) with Mn(CO)5Br in MeCN led to the formation of the Fe3Pb2-based trigonal-bipyramidal complexes [Fe3(CO)9{PbCr(CO)5}2](2-) (6) and [Fe3(CO)9{PbFe(CO)4}2](2-) (5), respectively. On the other hand, the Ru3Pb2-based trigonal-bipyramidal complex [Ru3(CO)9{PbCr(CO)5}2](2-) (7) was obtained directly from the reaction of PbCl2, Cr(CO)6, and Ru3(CO)12 in a KOH/MeOH solution. X-ray crystallography showed that 5 and 6 each had an Fe3Pb2 trigonal-bipyramidal core geometry, with three Fe(CO)3 groups occupying the equatorial positions and two PbFe(CO)4 or PbCr(CO)5 units in the axial positions, while 7 displayed a Ru3Pb2 trigonal-bipyramidal geometry with three equatorial Ru(CO)3 groups and two axial PbCr(CO)5 units. The complexes 3-7 were characterized spectroscopically, and their nature, formation, and electrochemistry were further examined by molecular orbital calculations at the B3LYP level of density functional theory.

  7. Bis(ortho-) chelated Monoanionic Bisphosphinoaryl Ruthenium(Ⅱ) Complexes:Synthesis,Characterization and Reactivity

    Institute of Scientific and Technical Information of China (English)

    van KLINK, Gerard P.M.; DANI, Paulo; van KOTEN, Gerard


    Bisphosphinoaryl ruthenium(Ⅱ) compounds are synthesized using two distinct synthetic routes. One route, direct cycloruthenation, consists of the reaction of the parent arene compound R-PCHP with [R uCl2(PPh)3] in chlorinated solvents. However, this route suffers from major drawbacks because HCl is formed as well as free triphenylphoshine. The other route, the transcyclometalation reaction, involves the interconversion of one cyclometalated ligand metal complex,[RuCl(NCN) (PPh3)], into another complex, [RuCl(RPCP) (PPh3) ], with concomitant consumption and formation of the corresponding arenes R-PCHP and NCHN, respectively.

  8. Synthesis, reactivity and electrochemical properties of substituted cyclopentadienyl cobalt (III) complexes

    Institute of Scientific and Technical Information of China (English)

    HOU, Xiu-Feng; HUANG, Zu-En; CAI, Rui-Fang; XU, You-Feng; PANG, Zhen


    Cyclopentadienyl cobalt complexes (η5-CsH4R)CoLI2 [L= CO,R=-COOOH2CH= CH2 (3); L=PPh3, R=-COOCH2- CH=CH2 (6); L= P(P-C6H4CH3)3, R=-COOC(CH3)= CH2 (7), -COOCH2C6H5 (8), -COOCH2CH== CH2 (9)] were prepared and characterized by elemental analyses, 1H NMR, IR and UV-vis spectra. The reaction of complexes (η5- CsH4R)CoLI2 [ L = CO, R = -COOC ( CH3 ) = CH2 (1), -COOCH2C6H5 (2); L = PPh3, R=-COOC(CH3) = CH2 (4), -COOCH2C6HH5 (5) ] with Na-Hg resdted in the forma tion of their corresponding substituted cobaltocene (η5 C5H4R)2Co [R=-COOC(CH3) = CH2 (10), -COOOH2C6H5 (11) ]. The electrochemical properties of these complexes 1 11 were studied by cyclic voitammetry. It was found that as theligand (L) of the cobalt(Ⅲ) complexes changing from CO to PPh3 and P(p-tolyl)3, their oxidation potentials in creased gradually. The cyclic voltammetry of a, α′-substituted cobaltocene showed reversible oxidation of one electron pro cess.

  9. Synthesis and reactivity of calix[4]arene-supported group 4 imido complexes. (United States)

    Dubberley, Stuart R; Friedrich, Andreas; Willman, David A; Mountford, Philip; Radius, Udo


    New mononuclear titanium and zirconium imido complexes [M(NR)(R'(2)calix)] [M=Ti, R'=Me, R=tBu (1), R=2,6-C(6)H(3)Me(2) (2), R=2,6-C(6)H(3)iPr(2) (3), R=2,4,6-C(6)H(2)Me(3) (4); M=Ti, R'=Bz, R=tBu (5), R=2,6-C(6)H(3)Me(2) (6), R=2,6-C(6)H(3)iPr(2) (7); M=Zr, R'=Me, R=2,6-C(6)H(3)iPr(2) (8)] supported by 1,3-diorganyl ether p-tert-butylcalix[4]arenes (R'(2)calix) were prepared in good yield from the readily available complexes [MCl(2)(Me(2)calix)], [Ti(NR)Cl(2)(py)(3)], and [Ti(NR)Cl(2)(NHMe(2))(2)]. The crystallographically characterised complex [Ti(NtBu)(Me(2)calix)] (1) reacts readily with CO(2), CS(2), and p-tolyl-isocyanate to give the isolated complexes [Ti[N(tBu)C(O)O](Me(2)calix)] (10), [[Ti(mu-O)(Me(2)calix)](2)] (11), [[Ti(mu-S)(Me(2)calix)](2)] (12), and [Ti[N(tBu)C(O)N(-4-C(6)H(4)Me)](Me(2)calix)] (13). In the case of CO(2) and CS(2), the addition of the heterocumulene to the Ti-N multiple bond is followed by a cycloreversion reaction to give the dinuclear complexes 11 and 12. The X-ray structure of 13.4(C(7)H(8)) clearly establishes the N,N'-coordination mode of the ureate ligand in this compound. Complex 1 undergoes tert-butyl/arylamine exchange reactions to form 2, 3, [Ti(N-4-C(6)H(4)Me)(Me(2)calix)] (14), [Ti(N-4-C(6)H(4)Fc)(Me(2)calix)] (15) [Fc=Fe(eta(5)-C(5)H(5))(eta(5)-C(5)H(4))], and [[Ti(Me(2)calix)](2)[mu-(N-4-C(6)H(4))(2)CH(2)

  10. Unsymmetrical tren-based ligands: synthesis and reactivity of rhenium complexes. (United States)

    Mösch-Zanetti, Nadia C; Köpke, Sinje; Herbst-Irmer, Regine; Hewitt, Manuel


    Reaction of bis(2-aminoethyl)(3-aminopropyl)amine with C(6)F(6) and K(2)CO(3) in DMSO yields unsymmetrical [(C(6)F(5))HNCH(2)CH(2)](2)NCH(2)CH(2)CH(2)NH(C(6)F(5)) ([N(3)N]H(3)). The tetraamine acts as a tridentate ligand in complexes of the type H[N(3)N]Re(O)X (X = Cl 1, Br 2) prepared by reacting Re(O)X(3)(PPh(3))(2) with [N(3)N]H(3) and an excess of NEt(3) in THF. Addition of 1 equiv of TaCH(CMe(2)Ph)Br(3)(THF)(2) to 1 gives the dimeric compound H[N(3)N]ClReOReBrCl[N(3)N]H (3) in quantitative yield that contains a Re(V)[double bond]O[bond]Re(IV) core with uncoordinated aminopropyl groups in each ligand. Addition of 2 equiv of TaCH(CMe(2)Ph)Cl(3)(THF)(2) to 1 leads to the chloro complex [N(3)N]ReCl (4) with all three amido groups coordinated to the metal, whereas by addition of 2 equiv of TaCH(CMe(2)Ph)Br(3)(THF)(2) to 2 the dibromo species H[N(3)N]ReBr(2) (5) with one uncoordinated amino group is isolated. Reduction of 4 under an atmosphere of dinitrogen with sodium amalgam gives the dinitrogen complex [N(3)N]Re(N(2)) (6). Single-crystal X-ray structure determinations have been carried out on complexes 1, 3, 5, and 6.

  11. Synthesis, structure, and reactivity of mononuclear RE(I) oximato complexes. (United States)

    Cuesta, Luciano; Huertos, Miguel A; Morales, Dolores; Pérez, Julio; Riera, Lucía; Riera, Víctor; Miguel, Daniel; Menéndez-Velazquez, Amador; García-Granda, Santiago


    Complexes [Re(ONCMe2)(CO)3(bipy)] (1) and [Re(ONCMe2)(CO)3(phen)] (2), synthesized by reaction of the respective triflato precursors [Re(OTf)(CO)3(N-N)] (N-N = bipy, phen) with KONCMe2, feature O-bonded monodentate oximato ligands. Compound [Re(CO)3(phen)(HONCMe2)]BAr'4 (3), with a monodentate N-bonded oxime ligand, was prepared by reaction of [Re(OTf)(CO)3(phen)], HONCMe2, and NaBAr'4. Deprotonation of 3 afforded 2. The oximato complexes reacted with p-tolylisocyanate, p-tolylisothiocyanate, maleic anhydride, and tetracyanoethylene, affording the products of the insertion of the electrophile into the Re-O bond, compounds 4-7. One representative of each type of compound was fully characterized, including single-crystal X-ray diffraction. The reactions of 1 and 2 with dimethylacetylenedicarboxylate were found to involve first an insertion as the ones mentioned above but followed by incorporation of water, loss of acetone, and formation of the charge-separated neutral amido complexes 9 and 10. The structure of 9 and 10 was determined by X-ray diffraction, and key features of their electronic distribution were studied using a topological analysis of the electron density as obtained from the Fourier map.

  12. Synthesis, Reactivity, and Characterization of (-Hexacarbocyclic) Manganese Dicarbonyl Complexes with Sulfur and Phosphorus Ligands (United States)


    strained ring systems, fluorene 12,13c or carbazole, 13c or heteroatoms (0, S, or N) 13c was found to stabilize the deprotonated CpFe(arene) complexes...carbon atom rather than beneath the saturated ring carbon atom and is discussed in more detail in Chapter V.8 In 2b, the near random positioning of the...formation of d2 -cyclopropane observed in the MS analysis with peaks at 6 1.29 and 6 0.88 assigned to the two methyl groups and the ring protons

  13. Synthesis, crystal structure of diferrous complex and its reactivity with dioxygen

    Institute of Scientific and Technical Information of China (English)

    阎世平; 程鹏; 王庆伦; 廖代正; 姜宗慧; 王耕霖


    The dinuclear complex of [Fe2L{O2P(OPh)2}](CIO4)2 ·Et2O(1) (where L represents the dinucleating ligand N-Et-HPTB, anion of N, N, N’, N’-tetrakis (N-ethyl-2-benzimidazolyemethyl)-2-hydroxy-1, 3-diamino-propane) has been synthesized and crystallizes in the triclinic space group P T with cell constants α = 1.526(3) nm, b = 1.259 8(3) nm, c = 1.563 0(3) nm , α = 94.41 (3)°, P = 115.31(3)°, β=99.90(3)°, V= 3.267(1) nm3, z=2, R = 0.084 7 and Rw = 0.177 8. The Fe(Ⅱ) sites are bridged by an alkoxide of the dinucleating ligand and a phosphate, affording a diiron core with an Fe-μ-O-Fe angle of 131.20(3)° and an Fe-Fe distance of 0.364 9 nm. Both Fe(II) centers have trigonal bipyramidal geometry. Dioxygen adduct (1/O2) forms upon exposure of the diferrous complex to O2 at low temperature (-60℃). The 1/O2 adduct is stable at -60℃ but decomposes upon warming. The adduct exhibits visible absorption maximum near 606 nm and resonance Raman features at 478 cm-1 (γFe-o) and 897 cm-1 (γo-o), and the latter

  14. Synthesis of PCP-supported nickel complexes and their reactivity with carbon dioxide. (United States)

    Schmeier, Timothy J; Nova, Ainara; Hazari, Nilay; Maseras, Feliu


    The Ni amide and hydroxide complexes [(PCP)Ni(NH(2))] (2; PCP=bis-2,6-di-tert-butylphosphinomethylbenzene) and [(PCP)Ni(OH)] (3) were prepared by treatment of [(PCP)NiCl] (1) with NaNH(2) or NaOH, respectively. The conditions for the formation of 3 from 1 and NaOH were harsh (2 weeks in THF at reflux) and a more facile synthetic route involved protonation of 2 with H(2)O, to generate 3 and ammonia. Similarly the basic amide in 2 was protonated with a variety of other weak acids to form the complexes [(PCP)Ni(2-Me-imidazole)] (4), [(PCP)Ni(dimethylmalonate)] (5), [(PCP)Ni(oxazole)] (6), and [(PCP)Ni(CCPh)] (7), respectively. The hydroxide compound 3, could also be used as a Ni precursor and treatment of 3 with TMSCN (TMS=trimethylsilyl) or TMSN(3) generated [(PCP)Ni(CN)] (8) or [(PCP)Ni(N(3))] (9), respectively. Compounds 3-7, and 9 were characterized by X-ray crystallography. Although 3, 4, 6, 7, and 9 are all four-coordinate complexes with a square-planar geometry around Ni, 5 is a pseudo-five-coordinate complex, with the dimethylmalonate ligand coordinated in an X-type fashion through one oxygen atom, and weakly as an L-type ligand through another oxygen atom. Complexes 2-9 were all reacted with carbon dioxide. Compounds 2-4 underwent facile reaction at low temperature to form the κ(1)-O carboxylate products [(PCP)Ni{OC(O)NH(2)}] (10), [(PCP)Ni{OC(O)OH}] (11), and [(PCP)Ni{OC(O)-2-Me-imidazole}] (12), respectively. Compounds 10 and 11 were characterized by X-ray crystallography. No reaction was observed between 5-9 and carbon dioxide, even at elevated temperatures. DFT calculations were performed to model the thermodynamics for the insertion of carbon dioxide into 2-9 to form a κ(1)-O carboxylate product and understand the pathways for carbon dioxide insertion into 2, 3, 6, and 7. The computed free energies indicate that carbon dioxide insertion into 2 and 3 is thermodynamically favorable, insertion into 8 and 9 is significantly uphill, insertion into 5 and 7

  15. Highly luminescent half-lantern cyclometalated platinum(II) complex: synthesis, structure, luminescence studies, and reactivity. (United States)

    Sicilia, Violeta; Forniés, Juan; Casas, José Ma; Martín, Antonio; López, José A; Larraz, Carmen; Borja, Pilar; Ovejero, Carmen; Tordera, Daniel; Bolink, Henk


    The half-lantern compound [{Pt(bzq)(μ-C(7)H(4)NS(2)-κN,S)}(2)]·Me(2)CO (1) was obtained by reaction of equimolar amounts of potassium 2-mercaptobenzothiazolate (KC(7)H(4)NS(2)) and [Pt(bzq)(NCMe)(2)]ClO(4). The Pt(II)···Pt(II) separation in the neutral complex [{Pt(bzq)(μ-C(7)H(4)NS(2)-κN,S)}(2)] is 2.910 (2) Å, this being among the shortest observed in half-lantern divalent platinum complexes. Within the complex, the benzo[h]quinoline (bzq) groups lie in close proximity with most C···C distances being between 3.3 and 3.7 Å, which is indicative of significant π-π interactions. The reaction of 1 with halogens X(2) (X(2) = Cl(2), Br(2), or I(2)) proceeds with a two-electron oxidation to give the corresponding dihalodiplatinum(III) complexes [{Pt(bzq)(μ-C(7)H(4)NS(2)-κN,S)X}(2)] (X = Cl 2, Br 3, I 4). Their X-ray structures confirm the retention of the half-lantern structure and the coordination mode of the bzq and the bridging ligand μ-C(7)H(4)NS(2)-κN,S. The Pt-Pt distances (Pt-Pt = 2.6420(3) Å 2, 2.6435(4) Å 3, 2.6690(3) Å 4) are shorter than that in 1 because of the Pt-Pt bond formation. Time dependent-density functional theory (TD-DFT) studies performed on 1 show a formal bond order of 0 between the metal atoms, with the 6p(z) contribution diminishing the antibonding character of the highest occupied molecular orbital (HOMO) and being responsible for an attractive intermetallic interaction. A shortening of the Pt-Pt distance from 2.959 Å in the ground state S(0) to 2.760 Å in the optimized first excited state (T(1)) is consistent with an increase in the Pt-Pt bond order to 0.5. In agreement with TD-DFT calculations, the intense, structureless, red emission of 1 in the solid state and in solution can be mainly attributed to triplet metal-metal-to-ligand charge transfer ((3)MMLCT) [dσ*(Pt-Pt) → π*(bzq)] excited states. The high quantum yields of this emission measured in toluene (44%) and solid state (62%) at room temperature indicate

  16. Synthesis, crystal structure of diferrous complex and its reactivity with dioxygen

    Institute of Scientific and Technical Information of China (English)


    The dinuclear complex of [ Fe2L{ O2P(OPh)2} ] (ClO4)2·Et2O(1) (where L represents the dinucleating ligand N-Et-HPTB, anion of N, N, N′, N′-tetrakis (N-ethyl-2-benzimidazolyemethyl)- 2-hydroxy-1, 3-diamino-propane) has been synthesized and crystallizes in the triclinic space group P with cell constants a = 1.526(3) nm, b = 1.259 8(3) nm, c = 1.563 0(3) nm , α= 94.41(3)°, β= 115.31(3)°, γ = 99.90(3)°, V = 3.267(1) nm3, z = 2, R = 0.084 7 and Rw = 0.177 8. The Fe(Ⅱ) sites are bridged by an alkoxide of the dinucleating ligand and a phosphate, affording a diiron core with an Fe-μ-O-Fe angle of 131.20(3)° and an Fe-Fe distance of 0.364 9 nm. Both Fe(Ⅱ) centers have trigonal bipyramidal geometry. Dioxygen adduct (1/O2) forms upon exposure of the diferrous complex to O2 at low temperature (-60℃). The 1/O2 adduct is stable at -60℃ but decomposes upon warming. The adduct exhibits visible absorption maximum near 606 nm and resonance Raman features at 478 cm-1 (γFe-O) and 897 cm-1 (γO-O), and the latter is the characteristic of a μ-1,2-peroxo species, indicating that dioxygen adducts can serve as models for the putative oxygenated intermediate of some non-heme diiron-oxo proteins.

  17. Synthesis and Reactivity of Iron-Iridium Heterobimetallic Complexes Using Tridentate Phosphine Ligands


    Nawar, N. [نجوى نوار


    Treatment of {Fe (CO)3 {(PPh2) 2 C=CH2}] with PPh2H gives the addition product [Fe (CO)3 {(PPh2) 2 CHCH2 PPh2}] (1). The uncoordinated phosphine group of complex 1 reacts with Ir4 (CO)12 to give mono-, di- and tri-substituted heterobimetallic cluster complexes. درس تفاعل المتراكب [} C0)3 Fe {(PPh2)2 C=CH2)] مع ثنائي فينيل الفوسفين وفق تفاعل مايكل للإضافة . ‏وقد استخدمت المتراكبات الناتجة في تحضير متراكبات ثنائية الفلز غير المتجانس . وقد أظهرت الدراسة أن مجموعة الفوسفين غير المرتبطة في ...

  18. Synthesis, characterization and reactivity of carbohydrate platinum(IV) complexes with thioglycoside ligands. (United States)

    Vetter, Cornelia; Pornsuriyasak, Papapida; Schmidt, Jürgen; Rath, Nigam P; Rüffer, Tobias; Demchenko, Alexei V; Steinborn, Dirk


    Reactions of fac-[PtMe3(4,4'-R2bpy)(Me2CO)][BF4] (R = H, 1a; tBu, 1b) and fac-[PtMe3(OAc-kappa2O,O')(Me2CO)] (2), respectively, with thioglycosides containing thioethyl (ch-SEt) and thioimidate (ch-STaz, Taz = thiazoline-2-yl) anomeric groups led to the formation of the carbohydrate platinum(IV) complexes fac-[PtMe3(4,4-R2bpy)(ch*)][BF4] (ch* = ch-SEt, 8-14; ch-STaz, 15-23) and fac-[PtMe3(OAc-kappa2O,O')(ch*)] (ch* = ch-SEt, 24-28; ch-STaz = 29-35), respectively. NMR (1H, 13C, 195Pt) spectroscopic investigations and a single-crystal X-ray diffraction analysis of 19 (ch-STaz = 2-thiazolinyl 2,3,4,6-tetra-O-benzoyl-1-thio-beta-D-galactopyranose) revealed the S coordination of the ch-SEt glycosides and the N coordination of the ch-STaz glycosides. Furthermore, X-ray structure analyses of the two decomposition products fac-[PtMe3(bpy)(STazH-kappaS)][BF4] (21a) and 1,6-anhydro-2,3,4-tri-O-benzoyl-beta-D-glucopyranose (23a), where a cleavage of the anomeric C-S bond had occurred in both cases, gave rise to the assumption that this decomposition was mediated due to coordination of the thioglycosides to the high electrophilic platinum(IV) atom, in non-strictly dried solutions. Reactions of fac-[PtMe3(Me2CO)3][BF4] (3) with ch-SEt as well as with ch-SPT and ch-Sbpy thioglycosides (PT = 4-(pyridine-2-yl)-thiazole-2-yl; bpy = 2,2'-bipyridine-6-yl), having N,S and N,N heteroaryl anomeric groups, respectively, led to the formation of platinum(IV) complexes of the type fac-[PtMe3(ch*)][BF4] (ch* = ch-SEt, 36-40, ch-SPT 42-44, ch-Sbpy 45, 46). The thioglycosides were found to be coordinated in a tridentate kappaS,kappa2O,O, kappaS,kappaN,kappaO and kappaS,kappa2N,N coordination mode, respectively. Analogous reactions with ch-STaz ligands succeeded for 2-thiazolinyl 2,3,4-tri-O-benzyl-6-O-(2,2'-bipyridine-6-yl)-1-thio-beta-D-glucopyranoside (5h) resulting in fac-[PtMe3(ch-STaz)][BF4] (41, ch-STaz = 5h), having a kappa3N,N',N''coordinated thioglycoside ligand.

  19. Synthesis, characterization and reactivity of carbohydrate platinum(IV) complexes with thioglycoside ligands† (United States)

    Vetter, Cornelia; Pornsuriyasak, Papapida; Schmidt, Jürgen; Rath, Nigam P.; Rüffer, Tobias; Demchenko, Alexei V.; Steinborn, Dirk


    Reactions of fac-[PtMe3(4,4′-R2bpy)(Me2CO)][BF4] (R = H, 1a; tBu, 1b) and fac-[PtMe3-(OAc-κ2O,O′)(Me2CO)] (2), respectively, with thioglycosides containing thioethyl (ch-SEt) and thioimidate (ch-STaz, Taz = thiazoline-2-yl) anomeric groups led to the formation of the carbohydrate platinum(IV) complexes fac-[PtMe3(4,4′-R2bpy)(ch*)][BF4] (ch* = ch-SEt, 8–14; ch-STaz, 15–23) and fac-[PtMe3(OAc-κ2O,O′)(ch*)] (ch* = ch-SEt, 24–28; ch-STaz = 29–35), respectively. NMR (1H, 13C, 195Pt) spectroscopic investigations and a single-crystal X-ray diffraction analysis of 19 (ch-STaz = 2-thiazolinyl 2,3,4,6-tetra-O-benzoyl-1-thio-β-d-galactopyranose) revealed the S coordination of the ch-SEt glycosides and the N coordination of the ch-STaz glycosides. Furthermore, X-ray structure analyses of the two decomposition products fac-[PtMe3(bpy)(STazH-κS)][BF4] (21a) and 1,6-anhydro-2,3,4-tri-O-benzoyl-β-d-glucopyranose (23a), where a cleavage of the anomeric C–S bond had occurred in both cases, gave rise to the assumption that this decomposition was mediated due to coordination of the thioglycosides to the high electrophilic platinum(IV) atom, in non-strictly dried solutions. Reactions of fac-[PtMe3(Me2CO)3][BF4] (3) with ch-SEt as well as with ch-SPT and ch-Sbpy thioglycosides (PT = 4-(pyridine-2-yl)-thiazole-2-yl; bpy = 2,2′-bipyridine-6-yl), having N,S and N,N heteroaryl anomeric groups, respectively, led to the formation of platinum(IV) complexes of the type fac-[PtMe3(ch*)][BF4] (ch* = ch-SEt, 36–40, ch-SPT 42–44, ch-Sbpy 45, 46). The thioglycosides were found to be coordinated in a tridentate κS,κ2O,O′, κS,κN,κO and κS,κ2N,N′ coordination mode, respectively. Analogous reactions with ch-STaz ligands succeeded for 2-thiazolinyl 2,3,4-tri-O-benzyl-6-O-(2,2′-bipyridine-6-yl)-1-thio-β-d-glucopyranoside (5h) resulting in fac-[PtMe3(ch-STaz)][BF4] (41, ch-STaz = 5h), having a κ3N,N′,N″ coordinated thioglycoside ligand. PMID:20517543

  20. On the reactivity of platinum(IV) complexes: Synthesis and spectroscopic studies of platinum(IV) complexes with hypoxanthine (United States)

    Gaballa, Akmal S.


    Na 2[PtCl 6] was found to react with (HypH)Cl·H 2O ( 2) (Hyp=hypoxanthine) in aqueous solution at room temperature yielding (HypH) 2[PtCl 6] ( 3). The same compound was obtained from hexachloroplatinic acid and hypoxanthine. Performing this reaction in methanol at 50 °C complex formation took place yielding the hypoxanthine complex [PtCl 4(Hyp) 2] ( 4). Both compounds were isolated in good yields as faint orange ( 3) and yellow ( 4) precipitates, respectively and characterized by microanalyses, IR and NMR ( 1H, 13C, 195Pt) spectroscopies as well as thermal analysis. Based on the data obtained an octahedral molecular structure is proposed for complex 4 with two hypoxanthine ligands coordinated through N7 to platinum(IV).

  1. Synthesis and reactivity of a conveniently prepared two-coordinate bis(amido) nickel(II) complex. (United States)

    Lipschutz, Michael I; Tilley, T Don


    A strictly two-coordinate nickel(II) bis(amido) complex has been prepared and its reactivity towards a variety of small molecules is described. Ni[N(SiMe(3))(DIPP)](2) reacts with DMAP and acetonitrile to form T-shaped three-coordinate complexes, and preliminary results show that Ni[N(SiMe(3))(DIPP)](2) is a catalyst for the hydrosilation of olefins with secondary silanes at ambient temperature.

  2. Early-transition-metal ketenimine complexes : Synthesis, reactivity, and structure of ketenimine-containing titanocene and zirconocene complexes

    NARCIS (Netherlands)

    Fandos, R; Lanfranchi, M; Otero, A; Pellinghelli, MA; Ruiz, MJ; Teuben, JH


    Reaction of Cp2M(PMe3)(2) complexes (M = Ti, Zr; Cp = eta(5)-C5H5) with the N-(p-tolyl)-diphenylketenimine Ph'N=C=CPh2 (Ph' = p-MeC6H4) in a 1:1 molar ratio affords the ketenimine-containing metallocene derivatives Cp2M(eta(2)-(C,N)-Ph'N=C=CPh2)(PMe3) (M = Ti (1); Zr (2)). The ketenimine ligand

  3. Silver complexes of 1,2,4-triazole derived N-heterocyclic carbenes: Synthesis, structure and reactivity studies

    Indian Academy of Sciences (India)

    Chandrakanta Dash; Mobin M Shaikh; Prasenjit Ghosh


    Two silver(I) complexes {[1-R-4-(-t4-butylacetamido)-1,2,4-triazol-5-ylidene]2Ag}+ Cl− [R = Et (1b), -Pr (2b)] of /-functionalized N-heterocyclic carbenes derived from 1,2,4-triazoles are reported. The silver complexes, 1b and 2b, have been synthesized from the reaction of the /-functionalized triazolium chloride salts namely, 1-R-4-(N-t-butylacetamido)-1,2,4-triazolium chloride [R = Et (1a), -Pr (2a)] by treatment with Ag2O in 53-56% yield. The 1,2,4-triazolium chloride salts 1a and 2a were prepared by the alkylation reaction of 1-R-1,2,4-triazole (R = Et, -Pr) with --butyl-2-chloro acetamide in 47-63% yield. The molecular structures of the silver(I) complexes, 1b and 2b, have been determined by X-ray diffraction studies. The density functional theory studies on the silver 1b and 2b complexes suggest that the 1,2,4-triazole derived N-heterocyclic carbenes to be strong −donating ligands similar to the now much recognized imidazolebased N-heterocyclic carbenes. The reactivity studies with (SMe2)AuCl and (SMe2)CuBr indicated the silver complexes, 1b and 2b, to be good transmetallating agents.

  4. Synthesis, characterization, and reactivity of furan- and thiophene-functionalized bis(n-heterocyclic carbene) complexes of iron(II)

    KAUST Repository

    Rieb, Julia


    The synthesis of iron(II) complexes bearing new heteroatom-functionalized methylene-bridged bis(N-heterocyclic carbene) ligands is reported. All complexes are characterized by single-crystal X-ray diffraction (SC-XRD), nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis. Tetrakis(acetonitrile)-cis-[bis(o-imidazol-2-ylidenefuran)methane]iron(II) hexafluorophosphate (2a) and tetrakis(acetonitrile)-cis-[bis(o-imidazol-2-ylidenethiophene)methane]iron(II) hexafluorophosphate (2b) were obtained by aminolysis of [Fe{N(SiMe3)2}2(THF)] with furan- and thiophene-functionalized bis(imidazolium) salts 1a and 1b in acetonitrile. The SC-XRD structures of 2a and 2b show coordination of the bis(carbene) ligand in a bidentate fashion instead of a possible tetradentate coordination. The four other coordination sites of these distorted octahedral complexes are occupied by acetonitrile ligands. Crystallization of 2a in an acetone solution by the slow diffusion of Et2O led to the formation of cisdiacetonitriledi[ bis(o-imidazol-2-ylidenefuran)methane]iron(II) hexafluorophosphate (3a) with two bis(carbene) ligands coordinated in a bidentate manner and two cis-positioned acetonitrile molecules. Compounds 2a and 2b are the first reported iron(II) carbene complexes with four coordination sites occupied by solvent molecules, and it was demonstrated that those solvent ligands can undergo ligand-exchange reactions.

  5. Synthesis of highly reactive polyisobutylene catalyzed by EtAlCl 2/Bis(2-chloroethyl) ether soluble complex in hexanes

    KAUST Repository

    Kumar, Rajeev Ananda


    The polymerization of isobutylene (IB) to yield highly reactive polyisobutylene (HR PIB) with high exo-olefin content using GaCl3 or FeCl3·diisopropyl ether complexes has been previously reported.1 In an effort to further improve polymerization rates and exo-olefin content, we have studied ethylaluminum dichloride (EADC) complexes with diisopropyl ether, 2-chloroethyl ethyl ether (CEEE), and bis(2-chloroethyl) ether (CEE) as catalysts in conjunction with tert-butyl chloride as initiator in hexanes at different temperatures. All three complexes were readily soluble in hexanes. Polymerization, however, was only observed with CEE. At 0 °C polymerization was complete in 5 min at [t-BuCl] = [EADC·CEE] = 10 mM and resulted in PIB with ∼70% exo-olefin content. Studies on complexation using ATR FTIR and 1H NMR spectroscopy revealed that at 1:1 stoichiometry a small amount of EADC remains uncomplexed. By employing an excess of CEE, exo-olefin contents increased up to 90%, while polymerization rates decreased only slightly. With decreasing temperature, polymerization rates decreased while molecular weights as well as exo-olefin contents increased, suggesting that isomerization has a higher activation energy than β-proton abstraction. Density functional theory (DFT) studies on the Lewis acid·ether binding energies indicated a trend consistent with the polymerization results. The polymerization mechanism proposed previously for Lewis acid·ether complexes1 adequately explains all the findings. © 2014 American Chemical Society.

  6. Progress in the synthesis and reactivity studies of metallabenzenes

    Institute of Scientific and Technical Information of China (English)

    HE Guomei; XIA Haiping; JIA Guocheng


    Metallabenzenes are metallacyclohexatriene complexes that are derived by replacement of one of the CH groups in benzene with a transition-metal fragment. Their synthesis and aromatic properties have recently attracted considerable attention. This paper summarizes the progress in the synthesis, aromatic property, and reactivity studies of metallabenzenes. We will describe the synthesis and reactivity of typical metallabenzenes with various metals (e.g. osmium, iridium, and ruthenium, etc.), the synthesis and structure of a recent reported example of metallanaphthalene and several rare examples of novel and stable metallabenzynes. Finally, the possible future developments in this field have also been suggested.

  7. Diene complexes of titanium, zirconium, and hafnium. Structure and reactivity

    NARCIS (Netherlands)

    Blenkers, Johannes


    This thesis describes a study of synthesis, characterization, and reactivity of novel n4-diene complexes of group IVB transition metals in low valence states. In the study of the reactivity, emphasus is put on reactions with simple substrate molecules, e.g. CO, H2, olefins, isocanides; in particular

  8. Reactivity of pi-complexes of Ti, V, and Nb towards dithioacetic acid: Synthesis and structure of novel metal sulfur-containing complexes (United States)

    Duraj, Stan A.; Andras, Maria T.; Hepp, Aloysius F.


    In order to use sulfur-containing resources economically and with minimal environmental damage, it is important to understand the desulfurization processes. Hydrodesulfurization, for example, is carried out on the surface of a heterogeneous metal sulfide catalyst. Studies of simple, soluble inorganic systems provide information regarding the structure and reactivity of sulfur-containing compounds with metal complexes. Further, consistent with recent trends in materials chemistry, many model compounds warrant further study as catalyst precursors. The reactivity of low-valent organometallic sandwich pi-complexes toward dithiocarboxylic acids is described. For example, treatment of bisbenzene vanadium with CH3CSSH affords a divanadium tetrakis(dithioacetate) complex. The crystallographically determined V-V bond distance, 2.800(2), is nearly the same as the V-V bond distance in a V(mu-nu squared-S2)2V' unit in the mineral patonite (VS4)n. The stability of the V2S4 core in the dimer is demonstrated by evidence of V2S4(+) in the mass spectrum (70 eV, solid probe) of the vanadium dimer. Several other systems relevant to HDS catalysis are also discussed.

  9. Synthesis and Reactivity of Four- and Five-Coordinate Low-Spin Cobalt(II) PCP Pincer Complexes and Some Nickel(II) Analogues. (United States)

    Murugesan, Sathiyamoorthy; Stöger, Berthold; Carvalho, Maria Deus; Ferreira, Liliana P; Pittenauer, Ernst; Allmaier, Günter; Veiros, Luis F; Kirchner, Karl


    Anhydrous CoCl2 or [NiCl2(DME)] reacts with the ligand PCP(Me)-iPr (1) in the presence of nBuLi to afford the 15e and 16e square planar complexes [Co(PCP(Me)-iPr)Cl] (2) and [Ni(PCP(Me)-iPr)Cl] (3), respectively. Complex 2 is a paramagnetic d(7) low-spin complex, which is a useful precursor for a series of Co(I), Co(II), and Co(III) PCP complexes. Complex 2 reacts readily with CO and pyridine to afford the five-coordinate square-pyramidal 17e complexes [Co(PCP(Me)-iPr)(CO)Cl] (4) and [Co(PCP(Me)-iPr)(py)Cl] (5), respectively, while in the presence of Ag(+) and CO the cationic complex [Co(PCP(Me)-iPr)(CO)2](+) (6) is afforded. The effective magnetic moments μeff of all Co(II) complexes were derived from the temperature dependence of the inverse molar magnetic susceptibility by SQUID measurements and are in the range 1.9 to 2.4 μB. This is consistent with a d(7) low-spin configuration with some degree of spin-orbit coupling. Oxidation of 2 with CuCl2 affords the paramagnetic Co(III) PCP complex [Co(PCP(Me)-iPr)Cl2] (7), while the synthesis of the diamagnetic Co(I) complex [Co(PCP(Me)-iPr)(CO)2] (8) was achieved by stirring 2 in toluene with KC8 in the presence of CO. Finally, the cationic 16e Ni(II) PCP complex [Ni(PCP(Me)-iPr)(CO)](+) (10) was obtained by reacting complex 3 with 1 equiv of AgSbF6 in the presence of CO. The reactivity of CO addition to Co(I), Co(II), and Ni(II) PCP square planar complexes of the type [M(PCP(Me)-iPr)(CO)] (n) (n = +1, 0) was investigated by DFT calculations, showing that formation of the Co species, 6 and 8, is thermodynamically favorable, while Ni(II) maintains the 16e configuration since CO addition is unfavorable in this case. X-ray structures of most complexes are provided and discussed. A structural feature of interest is that the apical CO ligand in 4 deviates significantly from linearity, with a Co-C-O angle of 170.0(1)°. The DFT-calculated value is 172°, clearly showing that this is not a packing but an electronic effect.

  10. Síntese e reatividade de complexos platina-trifenilestibina: uma revisão bibliográfica Synthesis and reactivity of triphenylstibine-platinum complexes: a bibliographic revision

    Directory of Open Access Journals (Sweden)

    Roberto Santos Barbiéri


    Full Text Available This article deals with synthesis and reactivity of complexes with triphenylstibine (SbPh3 as the ligand. A comparative study of analogous complexes of triphenylphosphine (PPh3 and triphenylarsine (AsPh3 with platinum in the oxidation states zero, two and four is included. The bibliographic revision includes publications since 1936, when the first Pt(II complex with triphenylstibine was described.

  11. Synthesis of a mononuclear, non-square-planar chromium(ii) bis(alkoxide) complex and its reactivity toward organic carbonyls and CO2. (United States)

    Yousif, Maryam; Cabelof, Alyssa C; Martin, Philip D; Lord, Richard L; Groysman, Stanislav


    In this paper, we report the synthesis and reactivity of a rare mononuclear chromium(ii) bis(alkoxide) complex, Cr(OR')2(THF)2, that is supported by a new bulky alkoxide ligand (OR' = di-t-butyl-(3,5-diphenylphenyl)methoxide). The complex is prepared by protonolysis of square-planar Cr(N(SiMe3)2)2(THF)2 with HOR'. X-ray structure determination disclosed that Cr(OR')2(THF)2 features a distorted seesaw geometry, in contrast to nearly all other tetra-coordinate Cr(ii) complexes, which are square-planar. The reactivity of Cr(OR')2(THF)2 with aldehydes, ketones, and carbon dioxide was investigated. Treatment of Cr(OR')2(THF)2 with two equivalents of aromatic aldehydes ArCHO (ArCHO = benzaldehyde, 4-anisaldehyde, 4-trifluorbenzaldehyde, and 2,4,6-trimethylbenzaldehyde) leads cleanly to the formation of Cr(iv) diolate complexes Cr(OR')2(O2C2H2Ar2) that were characterized by UV-vis and IR spectroscopies and elemental analysis; the representative complex Cr(OR')2(O2C2H2Ph2) was characterized by X-ray crystallography. In contrast, no reductive coupling was observed for ketones: treatment of Cr(OR')2(THF)2 with one or two equivalents of benzophenone forms invariably a single ketone adduct Cr(OR')2(OCPh2) which does not react further. QM/MM calculations suggest the steric demands prevent ketone coupling, and demonstrate that a mononuclear Cr(iii) bis-aldehyde complex with partially reduced aldehydes is sufficient for C-C bond formation. The reaction of Cr(OR')2(THF)2 with CO2 leads to the insertion of CO2 into a Cr-OR' bond, followed by complex rearrangement to form a diamagnetic dinuclear paddlewheel complex Cr2(O2COR')4(THF)2, that was characterized by NMR, UV-vis, and IR spectroscopy, and X-ray crystallography.

  12. Hodgkin-Reed-Sternberg cells in classical Hodgkin lymphoma show alterations of genes encoding the NADPH oxidase complex and impaired reactive oxygen species synthesis capacity. (United States)

    Giefing, Maciej; Winoto-Morbach, Supandi; Sosna, Justyna; Döring, Claudia; Klapper, Wolfram; Küppers, Ralf; Böttcher, Sebastian; Adam, Dieter; Siebert, Reiner; Schütze, Stefan


    The membrane bound NADPH oxidase involved in the synthesis of reactive oxygen species (ROS) is a multi-protein enzyme encoded by CYBA, CYBB, NCF1, NCF2 and NCF4 genes. Growing evidence suggests a role of ROS in the modulation of signaling pathways of non-phagocytic cells, including differentiation and proliferation of B-cell progenitors. Transcriptional downregulation of the CYBB gene has been previously reported in cell lines of the B-cell derived classical Hodgkin lymphoma (cHL). Thus, we explored functional consequences of CYBB downregulation on the NADPH complex. Using flow cytometry to detect and quantify superoxide anion synthesis in cHL cell lines we identified recurrent loss of superoxide anion production in all stimulated cHL cell lines in contrast to stimulated non-Hodgkin lymphoma cell lines. As CYBB loss proved to exert a deleterious effect on the NADPH oxidase complex in cHL cell lines, we analyzed the CYBB locus in Hodgkin and Reed-Sternberg (HRS) cells of primary cHL biopsies by in situ hybridisation and identified recurrent deletions of the gene in 8/18 cases. Immunohistochemical analysis to 14 of these cases revealed a complete lack of detectable CYBB protein expression in all HRS cells in all cases studied. Moreover, by microarray profiling of cHL cell lines we identified additional alterations of NADPH oxidase genes including CYBA copy number loss in 3/7 cell lines and a significant downregulation of the NCF1 transcription (p=0.006) compared to normal B-cell subsets. Besides, NCF1 protein was significantly downregulated (p<0.005) in cHL compared to other lymphoma cell lines. Together this findings show recurrent alterations of the NADPH oxidase encoding genes that result in functional inactivation of the enzyme and reduced production of superoxide anion in cHL.

  13. Well-defined bisMETAMORPhos PdI-PdI complex : Synthesis, structural characterization, and reactivity

    NARCIS (Netherlands)

    Oldenhof, Sander; Lutz, Martin; De Bruin, Bas; Van Der Vlugt, Jarl Ivar; Reek, Joost N H


    The formation of a bisMETAMORPhos PN-bridged dimeric PdI complex (3) from ligand 1 and Pd(dba)2 is described. The addition of 1 to Pd(dba)2 initially leads to the formation of Pd0 complex 2, which has a highly distorted tetrahedral environment and binds two neutral ligands 1. Complex 2 converts to {

  14. Well-​defined BisMETAMORPhos PdI-​PdI complex: synthesis, structural characterization, and reactivity

    NARCIS (Netherlands)

    Oldenhof, S.; Lutz, M.; de Bruin, B.; van der Vlugt, J.I.; Reek, J.N.H.


    The formation of a bisMETAMORPhos PN-​bridged dimeric PdI complex (3) from ligand 1 (I) and Pd(dba)​2 is described. The addn. of 1 to Pd(dba)​2 initially gives Pd0 complex [Pd(1)​2] (2)​, which has a highly distorted tetrahedral environment and binds two neutral ligands 1. Complex 2 converts to {PdI

  15. Well-​defined BisMETAMORPhos PdI-​PdI complex: synthesis, structural characterization, and reactivity

    NARCIS (Netherlands)

    Oldenhof, S.; Lutz, M.; de Bruin, B.; van der Vlugt, J.I.; Reek, J.N.H.


    The formation of a bisMETAMORPhos PN-​bridged dimeric PdI complex (3) from ligand 1 and Pd(dba)​2 is described. The addn. of 1 to Pd(dba)​2 initially leads to the formation of Pd0 complex 2, which has a highly distorted tetrahedral environment and binds two neutral ligands 1. Complex 2 converts to {

  16. Synthesis, characterization, and reactivity of a side-on manganese(iii)-peroxo complex bearing a pentadentate aminopyridine ligand. (United States)

    Du, Junyi; Xu, Daqian; Zhang, Chunxi; Xia, Chungu; Wang, Yong; Sun, Wei


    A manganese(ii) complex has been prepared with a proline-derived pentadentate ligand (Pro3Py), and it can be converted to a peroxomanganese(iii) complex in the presence of H2O2 and triethylamine. The resulting peroxomanganese(iii) complex was well characterised by UV-vis, EPR and ESI-MS techniques, and the geometric structure was discussed based on DFT calculations.

  17. Synthesis and Photocatalytic Reactivity of Vinylsulfonium Ylides. (United States)

    Klose, Immo; Misale, Antonio; Maulide, Nuno


    Although sulfur ylides are textbook reagents in organic synthesis, surprisingly little variation of substituents on sulfur is usually observed. In particular, vinylsulfonium ylides have been neglected so far. Herein, we present a study on their synthesis and reactivity, including interesting behavior under photocatalytic conditions.

  18. Synthesis, characterization, and ligand exchange reactivity of a series of first row divalent metal 3-hydroxyflavonolate complexes. (United States)

    Grubel, Katarzyna; Rudzka, Katarzyna; Arif, Atta M; Klotz, Katie L; Halfen, Jason A; Berreau, Lisa M


    A series of divalent metal flavonolate complexes of the general formula [(6-Ph(2)TPA)M(3-Hfl)]X (1-5-X; X = OTf(-) or ClO(4)(-); 6-Ph(2)TPA = N,N-bis((6-phenyl-2-pyridyl)methyl)-N-((2-pyridyl)methyl)amine; M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II); 3-Hfl = 3-hydroxyflavonolate) were prepared and characterized by X-ray crystallography, elemental analysis, FTIR, UV-vis, (1)H NMR or EPR, and cyclic voltammetry. All of the complexes have a bidentate coordinated flavonolate ligand. The difference in M-O distances (Delta(M-O)) involving this ligand varies through the series, with the asymmetry of flavonolate coordination increasing in the order Mn(II) approximately Ni(II) pi*) of the coordinated flavonolate ligand in 1-5-OTf (relative to that in free anion) increases in the order Ni(II) metals fit well with this ordering. (1)H NMR studies indicate that the 3-Hfl complexes of Co(II), Ni(II), and Zn(II) exhibit a pseudo-octahedral geometry in solution. EPR studies suggest that the Mn(II) complex 1-OTf may form binuclear structures in solution. The mononuclear Cu(II) complex 4-OTf has a distorted square pyramidal geometry. The oxidation potential of the flavonolate ligand depends on the metal ion present and/or the solution structure of the complex, with the Mn(II) complex 1-OTf exhibiting the lowest potential, followed by the pseudo-octahedral Ni(II) and Zn(II) 3-Hfl complexes, and the distorted square pyramidal Cu(II) complex 4-OTf. The Mn(II) complex [(6-Ph(2)TPA)Mn(3-Hfl)]OTf (1-OTf) is unique in the series in undergoing ligand exchange reactions in the presence of M(ClO(4))(2).6H(2)O (M = Co, Ni, Zn) in CD(3)CN to produce [(6-Ph(2)TPA)M(CD(3)CN)(n)](X)(2), [Mn(3-Hfl)(2).0.5H(2)O], and MnX(2) (X = OTf(-) or ClO(4)(-)). Under similar conditions, the 3-Hfl complexes of Co(II), Ni(II), and Cu(II) undergo flavonolate ligand exchange to produce [(6-Ph(2)TPA)M(CD(3)CN)(n)](X)(2) (M = Co, Ni, Cu; n = 1 or 2) and [Zn(3-Hfl)(2).2H(2)O]. An Fe(II) complex of 3-Hfl, [(6-Ph(2)TPA

  19. Cyclopentadienyl molybdenum(II/VI) N-heterocyclic carbene complexes: Synthesis, structure, and reactivity under oxidative conditions

    KAUST Repository

    Li, Shenyu


    A series of N-heterocyclic carbene (NHC) complexes CpMo(CO) 2(NHC)X (NHC = IMe = 1,3-dimethylimidazol-2-ylidene, X = Br, 1; NHC = 1,3-dipropylimidazol-2-ylidene, X = Br, 2; NHC = IMes = 1,3-bis(2,4,6- trimethylphenyl)imidazol-2-ylidene, X = Br, 3; NHC = IBz = 1,3-dibenzylimidazol- 2-ylidene, X = Br, 4a, and X = Cl, 4b; NHC = 1-methyl-3-propylimidazol-2- ylidene, X = Br, 5) and [CpMo(CO)2(IMes)(CH3CN)][BF 4] (6) have been synthesized and fully characterized. The stability of metal-NHC ligand bonds in these compounds under oxidative conditions has been investigated. The thermally stable Mo(VI) dioxo NHC complex [CpMoO 2(IMes)][BF4] (9) has been isolated by the oxidation of the ionic complex 6 by TBHP (tert-butyl hydrogen peroxide). Complex 6 can be applied as a very active (TOFs up to 3400 h-1) and selective olefin epoxidation catalyst. While under oxidative conditions (in the presence of TBHP), compounds 1-5 decompose into imidazolium bromide and imidazolium polyoxomolybdate. The formation of polyoxomolybdate as oxidation products had not been observed in a similar epoxidation catalyzed by Mo(II) and Mo(VI) complexes. DFT studies suggest that the presence of Br- destabilizes the CpMo(VI) oxo NHC carbene species, consistent with the experimental observations. © 2010 American Chemical Society.

  20. Mixed sandwich thorium complexes incorporating bis(tri-isopropylsilyl)cyclooctatetraenyl and pentamethylcyclopentadienyl ligands: synthesis, structure and reactivity. (United States)

    Button, Zoë E; Higgins, Jessica A; Suvova, Markéta; Cloke, F Geoffrey N; Roe, S Mark


    The Th(iv) mixed-sandwich halide complexes Th(COT(TIPS2))Cp*X (where COT(TIPS2) = 1,4-{Si(i)Pr(3)}(2)C(8)H(6), X = Cl, I) have been synthesised, and structurally characterised. When Th(COT(TIPS2))Cp*I is reduced in situ in the presence of CO(2), a mixture of dimeric carboxylate and oxalate complexes {Th(COT(TIPS2))Cp*}(2)(μ-κ(1):κ(2)-CO(3)) and {Th(COT(TIPS2))Cp*}(2)(μ-κ(2):κ(2)-C(2)O(4)) are formed, possibly via a transient Th(iii) species. Th(COT(TIPS2))Cp*Cl is readily alkylated to yield the benzyl complex Th(COT(TIPS2))Cp*CH(2)Ph, which reacts with CO(2) to form a carboxylate and with H(2) to form a hydride; the latter inserts CO(2), giving the bridging formate complex {Th(COT(TIPS2))Cp*(μ-κ(1):κ(1)-O(2)CH)}(2).

  1. Synthesis of highly reactive polyisobutylene with FeCl3/ether complexes in hexane; kinetic and mechanistic studies

    KAUST Repository

    Kumar, Rajeev Ananda


    The kinetics and mechanism of the polymerization of isobutylene catalyzed by FeCl3·ether complexes in hexane at 0°C were investigated. The polymerization rates increased in the diisopropyl ether< 2-chloroethyl ethyl ether < bis(2-chloroethyl) ether order, attributed to electronic effects. The polymerization rates increased with increasing initiator and catalyst concentrations. The first order plots, however, deviated from the linear suggesting that the cation concentration decreases with time. The previously proposed mechanism is inadequate to explain this finding. The decrease in the polymerization rate with time is explained by the low solubility of the H+ROR′FeCl4 - complexes that precipitate during polymerization. Based on mechanistic studies the revised mechanism now also includes the equilibrium H+ROR′FeCl4 - ⇋ HCl + FeCl3·ROR′.

  2. A thermally stable gold(III) hydride: synthesis, reactivity, and reductive condensation as a route to gold(II) complexes. (United States)

    Roşca, Dragoş-Adrian; Smith, Dan A; Hughes, David L; Bochmann, Manfred


    Going for gold: The first thermally stable gold(III) hydride [(C N C)*AuH] is presented. It undergoes regioselective insertions with allenes to give gold(III) vinyl complexes, and reductive condensation with [(C N C)*AuOH] to the air-stable Au(II) product, [(C N C)*(2)Au(2)], with a short nonbridged gold-gold bond.

  3. Synthesis and reactivity of the aquation product of the antitumor complex trans-[Ru(III)Cl4(indazole)2]-. (United States)

    Cebrián-Losantos, Berta; Reisner, Erwin; Kowol, Christian R; Roller, Alexander; Shova, Sergiu; Arion, Vladimir B; Keppler, Bernhard K


    Aquation of the investigational anticancer drug trans-[Ru(III)Cl4(Hind)2](-) (1, KP1019) results in the formation of mer,trans-[Ru(III)Cl3(Hind)2(H2O)] (2), which was isolated in high yield (85%) and characterized by spectroscopic methods and X-ray crystallography. Dissolution of 2 in acetone, led to its dimerization into [Ru(III)2(mu-Cl)2Cl4(Hind)4] x 2 (Me)2CO (3) in 79% yield, with release of two water molecules. Complex 2 reacts readily with nucleophilic organic molecules, viz., methanol or dimethyl sulfide, at room temperature by replacement of the aqua ligand to give mer,trans-[Ru(III)Cl3(Hind)2(MeOH)] (4) and mer,trans-[Ru(III)Cl3(Hind)2(Me2S)] (5) in 58 and 64% yield, respectively. By reaction of 2 with DMSO at room temperature or dimethyl sulfide at elevated temperatures trans,trans,trans-[Ru(II)Cl2(Hind)2(Me2S)2] (6) and trans,trans,trans-[Ru(II)Cl2(Hind)2(S-DMSO)2] (7) were prepared in 64 and 75% yield, respectively. Dissolution of 2 in acetonitrile or benzonitrile gave rise to mer,trans-[Ru(III)Cl3(Hind)(HNC(Me)ind)] (8a), mer,trans-[Ru(III)Cl3(Hind)(HNC(Ph)ind)] (8b), and trans,trans-[Ru(III)Cl2(HNC(Me)ind)2]Cl (9) in 67, 50, and 23% yield, respectively, upon metal-assisted iminoacylation of indazole, which is unprecedented for ruthenium(III). Furthermore, complex 2 reacts with the DNA-model bases 9-methyladenine (9-meade) and N6,N6-dimethyladenine (6-me2ade) to yield mer,trans-[Ru(III)Cl3(Hind)2(9-meade)] (10) and mer,trans-[Ru(III)Cl3(Hind)2(6-me2ade)] (11) with the purine bases bound to the Ru(III) center via N7 and N3, respectively. Complex 11 represents the first ruthenium complex in which the coordination of the purine ligand N6,N6-dimethyladenine occurs via N3. In addition, the polymer [Na(EtOAc)2Ru(III)(mu-Cl)4(Hind)2]n (12) was crystallized from ethyl acetate/diethyl ether solutions of Na[trans-Ru(III)Cl4(Hind)2] x 1.5 H2O (1a). The reported complexes were characterized by elemental analysis, IR and UV-vis spectroscopy, ESI mass spectrometry

  4. Synthesis, spectroscopic characterization and redox reactivity of some transition metal complexes with salicylaldimines bearing 2,6-di-phenylphenol (United States)

    Kasumov, V. T.; Köksal, Fevzi


    New bidentate N-(2,6-di-phenyl-1-hydroxyphenyl) salicylaldimines bearing X=H and 3,5-di- t-butyl substituents on the salicylaldehyde ring, L xH, and their copper(II) complexes, M(L x) 2, (M=Cu(II), Co(II), Pd(II), Ni(II) and Zn(II)) have been synthesized and characterized by IR, UV/vis, 1H NMR, 13C NMR, ESR spectroscopy, magnetic susceptibility measurements, as well as their oxidation with PbO 2 and reduction (for Cu(L x) 2) with PPh 3 were investigated. ESR studies indicate that oxidation of M(L x) 2 produces ligand-centered M II-phenoxyl radical species. The Cu(L x) 2 complexes, unlike others M(L x) 2, are readily reduced by PPh 3 via intramolecular electron transfer from ligand to copper(II) to give unstable radical intermediates which are converted to another stable secondary radical species. The analysis of ESR spectra of Cu(L x) 2, Co(L 1) 2 and generated phenoxyl radicals are presented.

  5. Microwave synthesis of mixed ligand diimine-thiosemicarbazone complexes of ruthenium(II): biophysical reactivity and cytotoxicity. (United States)

    Beckford, Floyd A; Shaloski, Michael; Leblanc, Gabriel; Thessing, Jeffrey; Lewis-Alleyne, Lesley C; Holder, Alvin A; Li, Liya; Seeram, Navindra P


    A novel microwave-assisted synthetic method has been used to synthesise a series of mixed ligand ruthenium(II) compounds containing diimine as well as bidentate thiosemicarbazone ligands. The compounds contain the diimine 1,10-phenanthroline (phen) or 2,2'-bipyridine (bpy) and the thiosemicarbazone is derived from 9-anthraldehyde. Based on elemental analyses and spectroscopic data, the compounds are best formulated as [(phen)(2)Ru(thiosemicarbazone)](PF(6))(2) and [(phen)(2)Ru(thiosemicarbazone)](PF(6))(2) where thiosemicarbazone = 9-anthraldehydethiosemicarbazone, 9-anthraldehyde-N(4)-methylthiosemicarbazone, and 9-anthraldehyde-N(4)-ethylthiosemicarbazone. Fluorescence competition studies with ethidium bromide, along with viscometric measurements suggests that the complexes bind calf thymus DNA (CTDNA) relatively strongly via an intercalative mode possibly involving the aromatic rings of the diimine ligands. The complexes show good cytotoxic profiles against MCF-7 and MDA-MB-231 (breast adenocarcinoma) as well as HCT 116 and HT-29 (colorectal carcinoma) cell lines.

  6. Dynamic Ligand Reactivity in a Rhodium Pincer Complex

    NARCIS (Netherlands)

    Tang, Zhou; Otten, Edwin; Reek, Joost N H; van der Vlugt, Jarl Ivar; de Bruin, Bas


    Ligand cooperativity provides (transition) metal complexes with new reactivities in substrate activation and catalytic reactions, but usually the ligand acts as an internal (Brønsted) base, while the metal acts as a (Lewis) acid. We describe the synthesis and stepwise activation of a new phosphane-p

  7. Synthesis, structure, and reactivity of tris(amidate) mono(amido) and tetrakis(amidate) complexes of group 4 transition metals. (United States)

    Payne, Philippa R; Thomson, Robert K; Medeiros, Diane M; Wan, Geoff; Schafer, Laurel L


    The syntheses of a series of tris(amidate) mono(amido) titanium and zirconium complexes are reported. The binding motif of the amidate ligand has been determined to depend on the size of the metal centre for these sterically demanding N,O-chelating ligands; the larger zirconium metal centre supports three κ(2)-(N,O) bound amidate ligands while the titanium analogue has one ligand bound in a κ(1)-(O) fashion to alleviate steric strain. Reactivity studies indicate that, despite high steric crowding about the tris(amidate) mono(amido) zirconium metal centre, transamination of the reactive dimethylamido ligand can be achieved using aniline. This complex is also an active precatalyst for intramolecular alkene hydroamination, in which protonolysis of one amidate ligand in the presence of excess amine is observed as an initiation step prior to catalytic turnover. Eight-coordinate homoleptic κ(2)-amidate complexes of zirconium and hafnium have also been prepared.

  8. Iron and cobalt complexes of 4,4,9,9-tetramethyl-5,8-diazadodecane-2, 11-dione dioxime ligand: Synthesis, characterization and reactivity studies

    Indian Academy of Sciences (India)

    Oindrila Das; Sayanti Chatterjee; Tapan Kanti Paine


    Two oximate bridged dinuclear complexes [Co$^{\\text{II}}_{2}$ (HL)2](ClO4)2 (1) and [Fe$^{text{II}}_{2}$ (HL)2](ClO4)2 (2), and a biomimetic iron(III)-catecholate complex [FeIII(HL)(DBC)] (3) of a dioxime ligand (H2L = 4,4,9,9-tetramethyl-5,8-diazadodecane-2,11-dione dioxime and DBCH2 = 3,5-di-tert-butylcatechol) were synthesized and characterized. X-ray single-crystal structures of both the dinuclear complexes exhibit an out-of-plane oximate bridge where the six-membered M2(NO)2 ring adopt a boat conformation with the metal ions in a fivecoordinate distorted trigonal bipyramidal geometry. Complexes 1 and 2 react with dioxygen at ambient condition to form the corresponding hydroxo- or oxo-bridged dinuclear cobalt(III) or iron(III) complexes. On the other hand, the iron(III)-catecholate complex (3) activate dioxygen to undergo oxidative C-C bond cleavage of catechol. The selective formation of extradiol catechol cleavage products in the reaction of 3 with dioxygen mimics the functional aspect of extradiol-cleaving catechol dioxygenases. The flexibility of ligand backbone is proposed to control the dioxygen reactivity of metal complexes.

  9. Cycloaddition reactivity studies of first-row transition metal-azide complexes and alkynes: an inorganic click reaction for metalloenzyme inhibitor synthesis. (United States)

    Evangelio, Emi; Rath, Nigam P; Mirica, Liviu M


    The studies described herein focus on the 1,3-dipolar cycloaddition reaction between first-row transition metal-azide complexes and alkyne reagents, i.e. an inorganic variant of the extensively used "click reaction". The reaction between the azide complexes of biologically-relevant metals (e.g., Fe, Co and Ni) found in metalloenzyme active sites and alkyne reagents has been investigated as a proof-of-principle for a novel method of developing metalloenzyme triazole-based inhibitors. Six Fe, Co and Ni mono-azide complexes employing salen- and cyclam-type ligands have been synthesized and characterized. The scope of the targeted inorganic azide-alkyne click reaction was investigated using the electron-deficient alkyne dimethyl acetylenedicarboxylate. Of the six metal-azide complexes tested, the Co and Ni complexes of the 1,4,8,11-tetrametyl-1,4,8,11-tetraazacyclotetradecane (Me(4)cyclam) ligand showed a successful cycloaddition reaction and formation of the corresponding metal-triazolate products, which were crystallographically characterized. Moreover, use of less electron deficient alkynes resulted in a loss of cycloaddition reactivity. Analysis of the structural parameters of the investigated metal-azide complexes suggests that a more symmetric structure and charge distribution within the azide moiety is needed for the formation of a metal-triazolate product. Overall, these results suggest that a successful cycloaddition reaction between a metal-azide complex and an alkyne substrate is dependent both on the ligand and metal oxidation state, that determine the electronic properties of the bound azide, as well as the electron deficient nature of the alkyne employed.

  10. Reactive organometallics from organotellurides: application in organic synthesis


    PRINCIVAL, Jefferson L.; Santos,Alcindo A. Dos; Comasseto,João V


    In this paper the preparation of reactive organometallics starting from organotellurides is reviewed. The application of the reactive organometallics prepared in this way in the synthesis of bioactive compounds is commented.

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

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


    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.

  12. Reactivity of rhodium(I) complexes bearing nitrogen-containing ligands toward CH3I: synthesis and full characterization of neutral cis-[RhX(CO)2(L)] and acetyl [RhI(μ-I)(COMe)(CO)(L)]2 complexes. (United States)

    Adcock, Romain J; Nguyen, Duc Hanh; Ladeira, Sonia; Le Berre, Carole; Serp, Philippe; Kalck, Philippe


    The neutral rhodium(I) square-planar complexes [RhX(CO)(2)(L)] [X = Cl (3), I (4)] bearing a nitrogen-containing ligand L [diethylamine (a), triethylamine (b), imidazole (c), 1-methylimidazole (d), pyrazole (e), 1-methylpyrazole (f), 3,5-dimethylpyrazole (g)] are straightforwardly obtained from L and [Rh(μ-X)(CO)(2)](2) [X = Cl (1), I (2)] precursors. The synthesis is extended to the diethylsulfide ligand h for 3h and 4h. According to the CO stretching frequency of 3 and 4, the ranking of the electronic density on the rhodium center follows the order b > a ≈ d > c > g > f ≈ h > e. The X-ray molecular structures of 3a, 3d-3f, 4a, and 4d-4f were determined. Results from variable-temperature (1)H and (13)C{(1)H} NMR experiments suggest a fluxional associative ligand exchange for 4c-4h and a supplementary hydrogen-exchange process in 4e and 4g. The oxidative addition reaction of CH(3)I to complexes 4c-4g affords the neutral dimeric iodo-bridged acetylrhodium(III) complexes [RhI(μ-I)(COCH(3))(CO)(L)](2) (6c-6g) in very good isolated yields, whereas 4a gives a mixture of neutral 6a and dianionic [RhI(2)(μ-I)(COCH(3))(CO)][NHMeEt(2)](2) and 4h exclusively provides the analogue dianionic complex with [SMeEt(2)](+) as the counterion. X-ray molecular structures for 6d(2) and 6e reveal that the two apical CO ligands are in mutual cis positions, as are the two apical d and e ligands, whereas isomer 6d(1) is centrosymmetric. Further reactions of 6d and 6e with CO or ligand e gave quantitatively the monomeric complexes [RhI(2)(COCH(3))(CO)(2)(d)] (7d) and [RhI(2)(COCH(3))(CO)(e)(2)] (8e), respectively, as confirmed by their X-ray structures. The initial rate of CH(3)I oxidative addition to 4 as determined by IR monitoring is dependent on the nature of the nitrogen-containing ligand. For 4a and 4h, reaction rates similar to those of the well-known rhodium anionic [RhI(2)(CO)(2)](-) species are observed and are consistent with the formation of this intermediate species

  13. Reactive plasma synthesis of nanocrystalline ceramic oxides (United States)

    Sreekumar, K. P.; Vijay, M.; Thiyagarajan, T. K.; Krishnan, K.; Ananthapadmanabhan, P. V.


    Reactive plasma synthesis is an attractive route to synthesize nanocrystalline materials. A 40 kW DC non-transferred arc plasma reactor has been designed and developed in our laboratory for synthesis of nanocrystalline materials. The main components of the plasma reactor include a 40 kW DC plasma generator or plasma torch, water-cooled reactor segment, product collection facility, DC power supply, cooling-water system and exhaust gas vent. The system has been used to synthesize nano-crystalline oxides of aluminium, titanium and zirconium. Aluminium metal powder was used as the starting material to synthesize alumina. The hydrides of Ti and Zr were used as the precursor for synthesis of nanocrystalline titania and zirconia respectively. The precursor powders were injected into the thermal plasma jet and were allowed to react with oxygen injected downstream the jet. The precursor powder particles were oxidized 'in-flight' to form nano-sized powder of the respective metal, which deposited on the walls of the reactor and collector assembly. Various analytical tools were used to characterized the products.

  14. Synthesis, spectroscopy, electrochemical and reactivity of cis and transtetra aminnitrosil ruthenium (II) complexes; Sintese, espectroscopia, eletroquimica e reatividade de complexos cis e transtetra aminnitrosil rutenio (II)

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Maria das Gracas


    A synthetic route was developed for the preparation of trans-[Ru(NH{sub 3}){sub 4} N O L]{sup n+} where L= isonicotinamide, pyrazine or sulfito and cis-[Ru(NH{sub 3}){sub 4} NONO{sub 2}]{sup 2+}. The complexes have been characterized by elemental analysis, UV-visible and infrared spectroscopies, molar conductance measurements, {sup 1}H NMR, EPR and cyclic voltammetry. All the complexes showed v(N O) in the characteristic range of NO{sup +}, and furthermore, they did not exhibit any signal in the EPR spectra, therefore in agreement with the formulation of Ru{sup 11}-NO{sup +}. The electronic spectra showed bands corresponding to d-d and charge transfer transitions types similarly to other nitrosyl complexes found in literature. Through the studies of the reactivity it was possible to calculate the K{sub eq} for the reaction: trans-[Ru(NH{sub 3}){sub 4} N O(isn)]{sup 3+} 2OH{sub -} trans-[Ru(NH{sub 3}){sub 4} NO{sub 2} (isn)]{sup +} + H{sub 2}O K{sub eq} = 2.5 x 10{sup 8} L{sup 2} mol{sup -2}. The cyclic voltammetry of the complexes exhibited reversible one-electron reduction in the potential range -0.13-0.38 V vs SCE. The reduction was attributed to [Ru{sup 11} (NH{sub 3}){sub 4} NO{sup +}LL]{sup n+}/[Ru{sup 11}(NH{sub 3}){sub 4} NO{sup 0}L]{sup (n-1)+}. A correlation was observed between v(N O) and E{sub 1/2} for the reversible reduction wave. These results indicate that reduction is facilitated by increasing strong {pi}acceptor property of the trans ligands to N O. Upon treatment with Zn(Hg) and Cd(Hg), the reduction of the sulphite ligand in trans-[Ru(NH{sub 3}){sub 4} N O(SO{sub 3})]{sup +} occurs and the formation of the binuclear species, [N O(NH{sub 3}){sub 4} Ru S]{sub 2}{sup 6+}, bridged by disulphide group is observed. The complex have been characterized by near infrared and Raman spectroscopies besides the techniques used for the mononuclear complex. The results were in agreement with the formulation: [NO{sup +}(NH{sub 3}){sub 4} Ru{sup +3-} S-- SRu{sup 2

  15. Negatively charged Ir(iii) cyclometalated complexes containing a chelating bis-tetrazolato ligand: synthesis, photophysics and the study of reactivity with electrophiles. (United States)

    Fiorini, Valentina; Zacchini, Stefano; Raiteri, Paolo; Mazzoni, Rita; Zanotti, Valerio; Massi, Massimiliano; Stagni, Stefano


    The bis-tetrazolate dianion [1,2 BTB](2-), which is the deprotonated form of 1,2 bis-(1H-tetrazol-5-yl)benzene [1,2-H2BTB], is for the first time exploited as an ancillary N^N ligand for negatively charged [Ir(C^N)2(N^N)](-)-type complexes, where C^N is represented by cyclometalated 2-phenylpyridine (ppy) or 2-(2,4-difluorophenyl)pyridine (F2ppy). The new Ir(iii) complexes [Ir(ppy)2(1,2 BTB)]- and [Ir(F2ppy)2(1,2 BTB)]- have been fully characterised and the analysis of the X-ray structure of [Ir(ppy)2(1,2 BTB)]- confirmed the coordination of the [1,2 BTB](2-) dianion in a bis chelated fashion through the N-atoms adjacent to each of the tetrazolic carbons. Both of the new anionic Ir(iii) complexes displayed phosphorescence in the visible region, with intense sky-blue (λmax = 460-490 nm) or aqua (λmax = 490-520 nm) emissions originating from [Ir(F2ppy)2(1,2 BTB)]- and [Ir(ppy)2(1,2 BTB)]-, respectively. In comparison with our very recent examples of anionic Ir(iii)tetrazolate cyclometalates, the new Ir(iii) tris chelate complexes [Ir(F2ppy)2(1,2 BTB)]- and [Ir(ppy)2(1,2 BTB)]-, display an improved robustness, allowing the study of their reactivity toward the addition of electrophiles such as H(+) and CH3(+). In all cases, the electrophilic attacks occurred at the coordinated tetrazolate rings, involving the reversible - by a protonation deprotonation mechanism - or permanent - upon addition of a methyl moiety - switching of their global net charge from negative to positive and, in particular, the concomitant variation of their photoluminescence output. The combination of the anionic complexes [Ir(F2ppy)2(1,2 BTB)]- or [Ir(ppy)2(1,2 BTB)]- with a deep red emitting (λmax = 686 nm) cationic Ir(iii) tetrazole complex such as [IrTPYZ-Me]+, where TPYZ-Me is 2-(2-methyl-2H-tetrazol-5-yl)pyrazine, gave rise to two fully Ir(iii)-based soft salts capable of displaying additive and O2-sensitive emission colours, with an almost pure white light obtained by the appropriate

  16. Synthesis and Reactivity of a Cerium(III Scorpionate Complex Containing a Redox Non-Innocent 2,2′-Bipyridine Ligand

    Directory of Open Access Journals (Sweden)

    Fabrizio Ortu


    Full Text Available The Ce(III hydrotris(3,5-dimethylpyrazolylborate complex [Ce(TpMe22(κ2-dmpz] (1 (TpMe2 = {HB(dmpz3}−; dmpz = 3,5-dimethylpyrazolide was isolated in fair yield from the reaction of [Ce(I3(THF4] with two equivalents of [K(TpMe2] via the facile decomposition of TpMe2. [Ce(TpMe22(bipy] (2 was synthesized in poor yield by the “one-pot” reaction of [Ce(I3(THF4], bipy (bipy = 2,2′-bipyridine, KC8 and two equivalents of [K(TpMe2] in tetrahydrofuran (THF. The reaction of 2 with N-methylmorpholine-N-oxide produced the known decomposition product [Ce(TpMe2(μ-BOpMe2]2 (3 (BOpMe2 = {HBO(dmpz2}2− in poor yield, presumably by N–O and B–N bond cleavage of a reactive intermediate. The reaction of 2 with trimethylsilylazide gave [Ce(TpMe22(N3] (4 in poor yield; the fate of bipy and the trimethylsilyl group is unknown. Complexes 1–4 were characterized by single crystal XRD, NMR and FTIR spectroscopy and elemental analysis. Complex 2 was additionally probed by UV/Vis/NIR and Electron Paramagnetic Resonance (EPR spectroscopies, Cyclic Voltammetry (CV and magnetometry, which together indicate a formal 4f1 Ce(III center coordinated by a bipy·− radical anion in this system.

  17. Synthesis and Luminescence Properties of a Reactive Ternary Europium Complex Containing 1, 10-Phenanthroline%基于邻菲咯啉的反应型三元铕配合物的合成与荧光性质

    Institute of Scientific and Technical Information of China (English)

    徐存进; 施燕琴


    以二苯甲酰甲烷(HDBM)为第一配体,5-丙烯酰胺基-1,10-菲咯啉(Aphen)为活性第二配体,制备了新的反应型三元铕配合物Eu(DBM)3Aphen.通过元素分析、红外光谱和热分析对配合物进行了组成确定,采用紫外光谱、荧光光谱、荧光寿命和荧光量子产量研究了配合物的光物理性能.结果表明,在紫外光激发下,配合物Eu(DBM)3Aphen能发射Eu3+的特征荧光,其荧光发射强度、单色性、荧光寿命和荧光量子产率等均显著高于文献报道的丙烯酸配合物Eu(DBM)2AA的相应数值,表明配合物Eu(DBM)3 Aphen不仅可作为潜在的红色发光材料,还可作为反应型的配合物,为制备具有优异发光性能的稀土聚合物提供了一条新的途径.%With dibenzoylmethane (HDBM) as the first ligand and 5-acrylamido-l, 10-phenanthroline as the secondary ligand, a new reactive ternary europium complex, Eu(DBM)3Aphen, was prepared and characterized by elemental analysis, IR spectra and TG-DTG. Its photophysical properties were studied by using UV, luminescence spectra, lifetime and quantum yield measurements. The complex Eu(DBM)3 Aphen showed characteristic luminescence of europium ions under UV excitation. Compared with the complex Eu(DBM)2 AA reported in the literature, complex Eu(DBM)3 Aphen exhibited much stronger luminescence intensity, higher monochromaticity, longer lifetime and higher efficiency. The results showed that the complex Eu(DBM)3 Aphen would be not only a potential red-emitting material but also a reactive complex, which would provide a new way for the synthesis of rare earth polymer with outstanding luminescence properties.

  18. Low-valent organometallics--synthesis, reactivity, and potential applications. (United States)

    Schulz, Stephan


    General concepts for the synthesis and stabilization of low-valent organometallic complexes of Groups 2, 12, 13, and 15 metals and common structural motifs are described. While kinetically stabilized complexes are in the focus for more than two decades, the principle of base-stabilization only recently allowed the synthesis of unforeseen compounds. As-prepared complexes not only show fascinating structural diversities, but exhibit also very interesting chemical properties. Low-valent complexes are of particular interest in the synthesis of novel molecular complexes, but may also find applications as tailor-made precursors for the synthesis of nanosized materials.

  19. Synthesis, crystal structures and reactivity of copper(I) amidate complexes with aryl halides: insight into copper(I)-catalyzed Goldberg reaction. (United States)

    Liu, Xinfang; Zhang, Songlin; Ding, Yuqiang


    In this paper, copper(I) amidate complexes (2-3), proposed intermediates in copper-catalyzed Goldberg reaction, have been prepared and characterized by elemental analysis, IR, (1)H NMR and X-ray crystallography. Ancillary ligand bis(diphenylphosphino)ferrocene (dppf) has contributed greatly to the stability of the copper-amidate complexes due to its strong chelating ability and weak intermolecular interactions. Thermal gravimetric analyses are carried out to determine the thermal competency of complexes 2-3 as the intermediates of the high-temperature Goldberg reactions. Reaction of complexes 2 and 3 with aryl halides generates the N-arylation products 5-8, accompanied by the formation of a copper(I) complex Cu(dppf)X (X = I or Br) 4, which has been determined by LC-MS analysis. These results provide new evidence for the mechanism of copper(I)-catalyzed Goldberg reaction.

  20. Synthesis and novel reactivity of halomethyldimethylsulfonium salts (United States)

    Xu; Fletcher; Dolbier Jr WR


    Iodomethyl-, chloromethyl-, and fluoromethyldimethylsulfonium salts, 4b-d, have been synthesized and are observed to be highly reactive molecules that exhibit extraordinary diversity with respect to the nature of their reactivity, undergoing facile direct substitution (S(N)2) reactions, but also being highly susceptible to electron-transfer reactions. Cyclic voltametry experiments indicated that the iodomethyldimethylsulfonium compound, 4b, is a potent electron acceptor, even surpassing the reactivity of perfluoro-n-alkyl iodides in that capacity. The iodo- and chloromethyldimethylsulfonium salts, 4b,c, as well as the analogous iodomethyltrimethylammonium salt, 3a, are shown to be reactive SET acceptors.

  1. Synthesis and reactivity of iron complexes with a new pyrazine-based pincer ligand, and application in catalytic low-pressure hydrogenation of carbon dioxide. (United States)

    Rivada-Wheelaghan, Orestes; Dauth, Alexander; Leitus, Gregory; Diskin-Posner, Yael; Milstein, David


    A novel pincer ligand based on the pyrazine backbone (PNzP) has been synthesized, (2,6-bis(di(tert-butyl)phosphinomethyl)pyrazine), tBu-PNzP. It reacts with FeBr2 to yield [Fe(Br)2(tBu-PNzP)], 1. Treatment of 1 with NaBH4 in MeCN/MeOH gives the hydride complex [Fe(H)(MeCN)2(tBu-PNzP)][X] (X = Br, BH4), 2·X. Counterion exchange and exposure to CO atmosphere yields the complex cis-[Fe(H)(CO)(MeCN)(tBu-PNzP)][BPh4] 4·BPh4, which upon addition of Bu4NCl forms [Fe(H)(Cl)(CO)(tBu-PNzP)] 5. Complex 5, under basic conditions, catalyzes the hydrogenation of CO2 to formate salts at low H2 pressure. Treatment of complex 5 with a base leads to aggregates, presumably of dearomatized species B, stabilized by bridging to another metal center by coordination of the nitrogen at the backbone of the pyrazine pincer ligand. Upon dissolution of compound B in EtOH the crystallographically characterized complex 7 is formed, comprised of six iron units forming a 6-membered ring. The dearomatized species can activate CO2 and H2 by metal-ligand cooperation (MLC), leading to complex 8, trans-[Fe(PNzPtBu-COO)(H)(CO)], and complex 9, trans-[Fe(H)2(CO)(tBu-PNzP)], respectively. Our results point at a very likely mechanism for CO2 hydrogenation involving MLC.

  2. Photochemical route to actinide-transition metal bonds: synthesis, characterization and reactivity of a series of thorium and uranium heterobimetallic complexes

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Ashleigh; Lukens, Wayne; Lu, Connie; Arnold, John


    A series of actinide-transition metal heterobimetallics has been prepared, featuring thorium, uranium and cobalt. Complexes incorporating the binucleating ligand N[-(NHCH2PiPr2)C6H4]3 and Th(IV) (4) or U(IV) (5) with a carbonyl bridged [Co(CO)4]- unit were synthesized from the corresponding actinide chlorides (Th: 2; U: 3) and Na[Co(CO)4]. Irradiation of the isocarbonyls with ultraviolet light resulted in the formation of new species containing actinide-metal bonds in good yields (Th: 6; U: 7); this photolysis method provides a new approach to a relatively rare class of complexes. Characterization by single-crystal X-ray diffraction revealed that elimination of the bridging carbonyl is accompanied by coordination of a phosphine arm from the N4P3 ligand to the cobalt center. Additionally, actinide-cobalt bonds of 3.0771(5) and 3.0319(7) for the thorium and uranium complexes, respectively, were observed. The solution state behavior of the thorium complexes was evaluated using 1H, 1H-1H COSY, 31P and variable-temperature NMR spectroscopy. IR, UV-Vis/NIR, and variable-temperature magnetic susceptibility measurements are also reported.

  3. Influence of Schiff base and lanthanide metals on the synthesis, stability, and reactivity of monoamido lanthanide complexes bearing two Schiff bases. (United States)

    Han, Fubin; Teng, Qiaoqiao; Zhang, Yong; Wang, Yaorong; Shen, Qi


    The monoamido lanthanide complexes stabilized by Schiff base ligand L(2)LnN(TMS)(2) (L = 3,5-Bu(t)(2)-2-(O)-C(6)H(2)CH═N-8-C(9)H(6)N, Ln = Yb (1), Y (2), Eu (3), Nd (4), and La (5)) were synthesized in good yields by the reactions of Ln[N(TMS)(2)](3) with 1.8 equiv of HL in hexane at room temperature. It was found that the stability of 1-5 depends greatly on the size of the lanthanide metals with the increasing trend of Yb ≈ Y metals of Y and Yb, L''(2)LnN(TMS)(2) (Ln = Yb (13) and Y (14)), and the more stable tris-Schiff base complexes with the large metals of La and Nd, yielded L''(3)Ln as the only product. Complexes 1-14 were fully characterized including X-ray crystal structural analysis. Complexes 1-5, 10, and 14 can serve as the efficient catalysts for addition of amines to carbodiimides, and the catalytic activity is greatly affected by the lanthanide metals with the active sequence of Yb < Y < Eu ≈ Nd ≈ La.

  4. Photochemical route to actinide-transition metal bonds: synthesis, characterization and reactivity of a series of thorium and uranium heterobimetallic complexes. (United States)

    Ward, Ashleigh L; Lukens, Wayne W; Lu, Connie C; Arnold, John


    A series of actinide-transition metal heterobimetallics has been prepared, featuring thorium, uranium, and cobalt. Complexes incorporating the binucleating ligand N[ο-(NHCH2P(i)Pr2)C6H4]3 with either Th(IV) (4) or U(IV) (5) and a carbonyl bridged [Co(CO)4](-) unit were synthesized from the corresponding actinide chlorides (Th: 2; U: 3) and Na[Co(CO)4]. Irradiation of the resulting isocarbonyls with ultraviolet light resulted in the formation of new species containing actinide-metal bonds in good yields (Th: 6; U: 7); this photolysis method provides a new approach to a relatively unusual class of complexes. Characterization by single-crystal X-ray diffraction revealed that elimination of the bridging carbonyl and formation of the metal-metal bond is accompanied by coordination of a phosphine arm from the N4P3 ligand to the cobalt center. Additionally, actinide-cobalt bonds of 3.0771(5) Å and 3.0319(7) Å for the thorium and uranium complexes, respectively, were observed. The solution-state behavior of the thorium complexes was evaluated using (1)H, (1)H-(1)H COSY, (31)P, and variable-temperature NMR spectroscopy. IR, UV-vis/NIR, and variable-temperature magnetic susceptibility measurements are also reported.

  5. Synthesis of group 10 metal complexes with a new unsymmetrical PN3P-pincer ligand through ligand post-modification: Structure and reactivity

    KAUST Repository

    Wang, Xiufang


    A post-modification strategy are used to synthesize a new class of diimine-amido PN3P-pincer group-10 transition metal complexes. The coordination chemistry and the thermal stabilities of their organometallic derivatives are characterized and investigated.

  6. Actinide metals with multiple bonds to carbon: synthesis, characterization, and reactivity of U(IV) and Th(IV) bis(iminophosphorano)methandiide pincer carbene complexes. (United States)

    Ma, Guibin; Ferguson, Michael J; McDonald, Robert; Cavell, Ronald G


    Treatment of ThCl(4)(DME)(2) or UCl(4) with 1 equiv of dilithiumbis(iminophosphorano) methandiide, [Li(2)C(Ph(2)P═NSiMe(3))(2)] (1), afforded the chloro actinide carbene complexes [Cl(2)M(C(Ph(2)P═NSiMe(3))(2))] (2 (M = Th) and 3 (M = U)) in situ. Stable PCP metal-carbene complexes [Cp(2)Th(C(Ph(2)P═NSiMe(3))(2))] (4), [Cp(2)U(C(Ph(2)P═NSiMe(3))(2))] (5), [TpTh(C(Ph(2)P═NSiMe(3))(2))Cl] (6), and [TpU(C(Ph(2)P═NSiMe(3))(2))Cl] (7) were generated from 2 or 3 by further reaction with 2 equiv of thallium(I) cyclopentadienide (CpTl) in THF to yield 4 or 5 or with 1 equiv of potassium hydrotris(pyrazol-1-yl) borate (TpK) also in THF to give 6 or 7, respectively. The derivative complexes were isolated, and their crystal structures were determined by X-ray diffraction. All of these U (or Th)-carbene complexes (4-7) possess a very short M (Th or U)═carbene bond with evidence for multiple bond character. Gaussian 03 DFT calculations indicate that the M═C double bond is constructed by interaction of the 5f and 6d orbitals of the actinide metal with carbene 2p orbitals of both π and σ character. Complex 3 reacted with acetonitrile or benzonitrile to cyclo-add C≡N to the U═carbon double bond, thereby forming a new C-C bond in a new chelated quadridentate ligand in the bridged dimetallic complexes (9 and 10). A single carbon-U bond is retained. The newly coordinated uranium complex dimerizes with one equivalent of unconverted 3 using two chlorides and the newly formed imine derived from the nitrile as three connecting bridges. In addition, a new crystal structure of [CpUCl(3)(THF)(2)] (8) was determined by X-ray diffraction.

  7. Cyclopalladation of dimesityl selenide: synthesis, reactivity, structural characterization, isolation of an intermediate complex with C-H···Pd intra-molecular interaction and computational studies. (United States)

    Kolay, Siddhartha; Wadawale, Amey; Das, Dasarathi; Kisan, Hemanta K; Sunoj, Raghavan B; Jain, Vimal K


    The reaction of dimesityl selenide (Mes2Se) with either PdCl2(PhCN)2 in toluene or PdCl2 in toluene-acetonitrile yields a chloro-bridged binuclear palladium complex, [Pd2Cl2(μ-Cl)2(Mes2Se)2] (1), whereas with Na2PdCl4 in refluxing ethanol, a cyclometallated palladium complex, [Pd2(μ-Cl)2{MesSeC6H2(Me2)CH2}2] (2) is afforded. 2 can also be obtained when 1 is refluxed in ethanol. On treatment with Pb(Epy)2 in dichloromethane, 2 afforded the Epy-bridged binuclear complexes, [Pd2(μ-Epy)2{MesSeC6H2(Me2)CH2}2] (3; E = S (3a) or Se (3b)). Treatment of 2 with PPh3 yields a bridge-cleaved monomeric complex, [PdCl{MesSeC6H2(Me2)CH2}(PPh3)]. The molecular structures of 1-3 were established by X-ray diffraction analyses. All the complexes are dimeric, with the palladium atoms acquiring a distorted square planar configuration. There are intra-molecular C-H···Pd interactions (d(M-H): 2.75 Å and

  8. Synthesis and Reactivity of Group 6 Metal Carbonyl Complexes with Bis(pyrazol-1-yl)methanes Modified by the Vinyltin Groups

    Institute of Scientific and Technical Information of China (English)

    WEN,Zhenkang; YANG,Zhi; SONG,Haibin; TANG,Liangfu


    Diphenyl(vinyl)stannylbis(3,5-dimethylpyrazol-1-yl)methane and diphenyl(vinyl)stannylbis(3,4,5-trimethyl-pyrazol-1-yl)methane have been synthesized by the reaction of bis(3,5-dimethylpyrazol-1-yl)methyl or bis(3,4,5-trimethylpyrazol-1-yl)methyllithium with diphenyl(vinyl)tin iodide. Treatment of these bis(pyrazol-l-yl)methanes modified by the vinyltin groups with M(CO)5THF (M=Mo and W) in refluxing THF resulted in new heterobimeto allic complexes R3SnCHPz2M(CO)3 (R3Sn represents trivinyltin or diphenyl(vinyl)tin, and Pz represents substituted pyrazol-1-yl), in which a vinyl group bonds to the molybdenum or tungsten atom in η2-fashion to lead to bis(pyrazol-1-yl)methanes acting as a tridentate κ3-(π,N,N) ligand. Reaction of (CH2 = CH)3SnCH(3,5-Me2Pz)2W(CO)3 and Ph2(CH2=CH)SnCH(3,5-Me2Pz)2W(CO)3 with I2 has been investigated. The former gave a complex CH2(3,5-Me2Pz)2W(CO)4, while the latter yielded a four-membered heterometallocyclic complex CH(3,5-Me2Pz)2W(CO)3 I with the loss of the organotin group. Treatment of this four-membered heterometallocyc-lic complex with PhSNa led to the iodide anion replaced by the thiophenolate anion to give a complex CH(3,5-Me2Pz)2W(CO)3SPh.

  9. Synthesis, characterization, and reactivity studies of a water-soluble bis(alkoxo)(carboxylato)-bridged diMn(III) complex modeling the active site in catalase. (United States)

    Palopoli, Claudia; Duhayon, Carine; Tuchagues, Jean-Pierre; Signorella, Sandra


    A new diMn(III) complex, Na[Mn2(5-SO3-salpentO)(μ-OAc)(μ-OMe)(H2O)]·4H2O, where 5-SO3-salpentOH = 1,5-bis(5-sulphonatosalicylidenamino)pentan-3-ol, has been prepared and characterized. ESI-mass spectrometry, paramagnetic (1)H NMR, EPR and UV-visible spectroscopic studies on freshly prepared solutions of the complex in methanol and 9 : 1 methanol-water mixtures showed that the compound retains the triply bridged bis(μ-alkoxo)(μ-acetato)Mn2(3+) core in solution. In the 9 : 1 methanol-water mixture, slow substitution of acetate by water molecules took place, and after one month, the doubly bridged diMn(III) complex, [Mn2(5-SO3-salpentO)(μ-OMe)(H2O)3]·5H2O, formed and could be characterized by X-ray diffraction analysis. In methanolic or aqueous basic media, acetate shifts from a bridging to a terminal coordination mode, affording the highly stable [Mn2(5-SO3-salpentO)(μ-OMe)(OAc)](-) anion. The efficiency of the complex in disproportionating H2O2 depends on the solvent and correlates with the stability of the complex (towards metal dissociation) in each medium: basic buffer > aqueous base > water. The buffer preserves the integrity of the catalyst and the rate of O2 evolution remains essentially constant after successive additions of excess of H2O2. Turnovers as high as 3000 mol H2O2 per mol of catalyst, without significant decomposition and with an efficiency of k(cat)/K(M) = 1028 M(-1) s(-1), were measured for the complex in aqueous buffers of pH 11. Kinetic and spectroscopic results suggest a catalytic cycle that runs between Mn(III)2 and Mn(IV)2 oxidation states, which is consistent with the low redox potential observed for the Mn(III)2/Mn(III)Mn(IV) couple of the catalyst in basic medium.

  10. Synthesis, characterization, and reactivity of Fe complexes containing cyclic diazadiphosphine ligands: the role of the pendant base in heterolytic cleavage of H2. (United States)

    Liu, Tianbiao; Chen, Shentan; O'Hagan, Molly J; Rakowski DuBois, Mary; Bullock, R Morris; DuBois, Daniel L


    The iron complexes CpFe(P(Ph)(2)N(Bn)(2))Cl (1-Cl), CpFe(P(Ph)(2)N(Ph)(2))Cl (2-Cl), and CpFe(P(Ph)(2)C(5))Cl (3-Cl)(where P(Ph)(2)N(Bn)(2) is 1,5-dibenzyl-1,5-diaza-3,7-diphenyl-3,7-diphosphacyclooctane, P(Ph)(2)N(Ph)(2) is 1,3,5,7-tetraphenyl-1,5-diaza-3,7-diphosphacyclooctane, and P(Ph)(2)C(5) is 1,4-diphenyl-1,4-diphosphacycloheptane) have been synthesized and characterized by NMR spectroscopy, electrochemical studies, and X-ray diffraction. These chloride derivatives are readily converted to the corresponding hydride complexes [CpFe(P(Ph)(2)N(Bn)(2))H (1-H), CpFe(P(Ph)(2)N(Ph)(2))H (2-H), CpFe(P(Ph)(2)C(5))H (3-H)] and H(2) complexes [CpFe(P(Ph)(2)N(Bn)(2))(H(2))]BAr(F)(4), [1-H(2)]BAr(F)(4), (where BAr(F)(4) is B[(3,5-(CF(3))(2)C(6)H(3))(4)](-)), [CpFe(P(Ph)(2)N(Ph)(2))(H(2))]BAr(F)(4), [2-H(2)]BAr(F)(4), and [CpFe(P(Ph)(2)C(5))(H(2))]BAr(F)(4), [3-H(2)]BAr(F)(4), as well as [CpFe(P(Ph)(2)N(Bn)(2))(CO)]BAr(F)(4), [1-CO]Cl. Structural studies are reported for [1-H(2)]BAr(F)(4), 1-H, 2-H, and [1-CO]Cl. The conformations adopted by the chelate rings of the P(Ph)(2)N(Bn)(2) ligand in the different complexes are determined by attractive or repulsive interactions between the sixth ligand of these pseudo-octahedral complexes and the pendant N atom of the ring adjacent to the sixth ligand. An example of an attractive interaction is the observation that the distance between the N atom of the pendant amine and the C atom of the coordinated CO ligand for [1-CO]BAr(F)(4) is 2.848 Å, considerably shorter than the sum of the van der Waals radii of N and C atoms. Studies of H/D exchange by the complexes [1-H(2)](+), [2-H(2)](+), and [3-H(2)](+) carried out using H(2) and D(2) indicate that the relatively rapid H/D exchange observed for [1-H(2)](+) and [2-H(2)](+) compared to [3-H(2)](+) is consistent with intramolecular heterolytic cleavage of H(2) mediated by the pendant amine. Computational studies indicate a low barrier for heterolytic cleavage of H(2). These

  11. Solution synthesis, structure, and CO{sub 2} reduction reactivity of a Scandium(II) complex, {Sc[N(SiMe_3)_2]_3}{sup -}

    Energy Technology Data Exchange (ETDEWEB)

    Woen, David H.; Chen, Guo P.; Ziller, Joseph W.; Furche, Filipp; Evans, William J. [Department of Chemistry, University of California, Irvine, CA (United States); Boyle, Timothy J. [Sandia National Laboratories, Advanced Materials Laboratory, Albuquerque, NM (United States)


    The first crystallographically characterizable complex of Sc{sup 2+}, [Sc(NR{sub 2}){sub 3}]{sup -} (R=SiMe{sub 3}), has been obtained by LnA{sub 3}/M reactions (Ln=rare earth metal; A=anionic ligand; M=alkali metal) involving reduction of Sc(NR{sub 2}){sub 3} with K in the presence of 2.2.2-cryptand (crypt) and 18-crown-6 (18-c-6) and with Cs in the presence of crypt. Dark maroon [K(crypt)]{sup +}, [K(18-c-6)]{sup +}, and [Cs(crypt)]{sup +} salts of the [Sc(NR{sub 2}){sub 3}]{sup -} anion are formed, respectively. The formation of this oxidation state of Sc is also indicated by the eight-line EPR spectra arising from the I=7/2 {sup 45}Sc nucleus. The Sc(NR{sub 2}){sub 3} reduction differs from Ln(NR{sub 2}){sub 3} reactions (Ln=Y and lanthanides) in that it occurs under N{sub 2} without formation of isolable reduced dinitrogen species. [K(18-c-6)][Sc(NR{sub 2}){sub 3}] reacts with CO{sub 2} to produce an oxalate complex, {K_2(18-c-6)_3}{[(R_2N)_3Sc]_2(μ-C_2O_4-κ"1O:κ"1O'')}, and a CO{sub 2}{sup -} radical anion complex, [(R{sub 2}N){sub 3}Sc(μ-OCO-κ{sup 1}O:κ{sup 1}O')K(18-c-6)]{sub n}. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Two Step Synthesis of a Non-symmetric Acetylcholinesterase Reactivator

    Directory of Open Access Journals (Sweden)

    Vit Koleckar


    Full Text Available The newly developed and very promising acetylcholinesterase reactivator (E-1- (2-hydroxyiminomethylpyridinium-4-(4-hydroxyiminomethylpyridinium-but-2-ene dibromide was prepared using two different pathways via a two-step synthesis involving the appropriate (E-1-(4-bromobut-2-enyl-2- or 4-hydroxyiminomethyl-pyridinium bromides. Afterwards, purities and yields of the desired product prepared by both routes were compared. Finally, its potency to reactivate several nerve agent-inhibited acetylcholinesterases was tested.

  13. Synthesis, structure, and reactivity of iridium perfluorocarbene complexes: regio- and stereo-specific addition of HCl across a metal carbon double bond. (United States)

    Yuan, Jian; Bourgeois, Cheryl J; Rheingold, Arnold L; Hughes, Russell P


    Reductive activation of an α-fluorine in the perfluoroalkyl complexes Cp*(L)(i)Ir-CF2RF using Mg/graphite leads to perfluorocarbene complexes Cp*(L)Ir[double bond, length as m-dash]CFRF (L = CO, PMe3; RF = CF3, C2F5, C6F5). New complexes E-Cp*(PMe3)Ir[double bond, length as m-dash]CFC2F5 and E-Cp*(CO)Ir[double bond, length as m-dash]CFC6F5 have been characterized by single crystal X-ray diffraction studies, and a comparison of metric parameters with previously reported analogues is reported. Experimental NMR and computational DFT (B3LYP/LACV3P**++) studies agree that for Ir[double bond, length as m-dash]CFRF complexes (RF = CF3, CF2CF3) the thermodynamic preference for the E or Z isomer depends on the steric requirements of ligand L; when L = CO the Z-isomer (F cis to Cp*) is preferred and for L = PMe3 the E-isomer is preferred. When reduction of the precursors is carried out in the dark the reaction is completely selective to produce E- or Z-isomers. Exposure of solutions of these compounds to ambient light results in slow conversion to a photostationary non-equilibrium mixture of E and Z isomers. In the dark, these E/Z mixtures convert thermally to their preferred E or Z equilibrium geometries in an even slower reaction. A study of the temperature dependent kinetics of this dark transformation allows ΔG(‡)298 for rotation about the Ir[double bond, length as m-dash]CFCF3 double bond to be experimentally determined as 25 kcal mol(-1); a DFT/B3LYP/LACV3P**++ calculation of this rotation barrier is in excellent agreement (27 kcal mol(-1)) with the experimental value. Reaction of HCl with toluene solutions of Cp*(L)Ir[double bond, length as m-dash]CFRF (L = CO, PMe3) or Cp*(CO)Ir[double bond, length as m-dash]C(CF3)2 at low temperature resulted in regiospecific addition of HCl across the metal carbon double bond, ultimately yielding Cp*(L)Ir(CHFRF)Cl and Cp*(CO)Ir[CH(CF3)2]Cl. Reaction of HCl with single E or Z diastereomers of Cp*(L)Ir[double bond, length as m

  14. Design and synthesis of reactive separation systems

    Energy Technology Data Exchange (ETDEWEB)

    Doherty, M.F.


    During the last decade there has been a rapid upturn in interest in reactive distillation. The chemical process industry recognizes the favorable economics of carrying out reaction simultaneously with distillation for certain classes of reacting systems, and many new processes have been built based on this technology. Interest is also increasing by academics and software vendors. Systematic design methods for reactive distillation systems have only recently begun to emerge. In this report we survey the available design techniques and point out the contributions made by our group at the University of Massachusetts.

  15. Tetrakis(bis(trimethylsilyl)amido)uranium(IV): synthesis and reactivity. (United States)

    Lewis, Andrew J; Williams, Ursula J; Carroll, Patrick J; Schelter, Eric J


    The synthesis of the sterically saturated uranium(IV) complex U[N(SiMe3)2]4 (1) is demonstrated from the one-electron oxidation of U[N(SiMe3)2]3 with a variety of oxidants in THF. A high yielding synthesis of 1 directly from UI3(THF)4 is provided.

  16. Glycosyltransferase complexes improve glycolipid synthesis. (United States)

    Spessott, Waldo; Crespo, Pilar M; Daniotti, José Luis; Maccioni, Hugo J F


    The synthesis of gangliosides GM3 and GD3 is carried out by the successive addition of sialic acid residues on lactosylceramide (LacCer) by the Golgi located sialyltransferases Sial-T1 and Sial-T2, respectively. CHO-K1 cells lack Sial-T2 and only express GM3. Here we show that the activity of Sial-T1 was near 2.5-fold higher in homogenates of CHO-K1 cells transfected to express Sial-T2 (CHO-K1(Sial-T2)) than in untransfected cells. The appearance of Sial-T1 enzyme or gene transcription activators or the stabilization of the Sial-T1 protein were discarded as possible causes of the activation. Sial-T2 lacking the catalytic domain failed to promote Sial-T1 activation. Since Gal-T1, Sial-T1 and Sial-T2 form a multienzyme complex, we propose that transformation of formed GM3 into GD3 and GT3 by Sial-T2 in the complex leaves Sial-T1 unoccupied, enabled for new rounds of LacCer utilization, which results in its apparent activation.

  17. Reactivity of organic compounds in catalytic synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Minachev, Kh.M.; Bragin, O.V.


    A comprehensive review of 1976 Soviet research on catalysis delivered to the 1977 annual session of the USSR Academy of Science Council on Catalysis (Baku 6/16-20/77) covers hydrocarbon reactions, including hydrogenation and hydrogenolysis, dehydrogenation, olefin dimerization and disproportionation, and cyclization and dehydrocyclization (e.g., piperylene cyclization and ethylene cyclotrimerization); catalytic and physicochemical properties of zeolites, including cracking, dehydrogenation, and hydroisomerization catalytic syntheses and conversion of heterocyclic and functional hydrocarbon derivatives, including partial and total oxidation (e.g., of o-xylene to phthalic anhydride); syntheses of thiophenes from alkanes and hydrogen sulfide over certain dehydrogenation catalysts; catalytic syntheses involving carbon oxides ( e.g., the development of a new heterogeneous catalyst for hydroformylation of olefins), and of Co-MgO zeolitic catalysts for synthesis of aliphatic hydrocarbons from carbon dioxide and hydrogen, and fabrication of high-viscosity lubricating oils over bifunctional aluminosilicate catalysts.

  18. Characteristics and reactivity of ruthenium-oxo complexes. (United States)

    Ishizuka, Tomoya; Kotani, Hiroaki; Kojima, Takahiko


    In this perspective, we have surveyed the synthetic procedure, characteristics, and reactivity of high-valent ruthenium-oxo complexes. The ruthenium-oxo complexes have served as ideal species to elucidate the characteristics of metal-oxo complexes in terms of not only geometrical and electronic structures but also oxidation reactivity and mechanisms of oxidation reactions. Due to the high stability and excellent reversibility of redox processes, ruthenium-oxo complexes have provided significant mechanistic insights into the oxidation of organic compounds including alcohols, alkenes, and alkanes and also water on the basis of detailed kinetic analysis.

  19. Complex cellular responses to reactive oxygen species. (United States)

    Temple, Mark D; Perrone, Gabriel G; Dawes, Ian W


    Genome-wide analyses of yeast provide insight into cellular responses to reactive oxygen species (ROS). Many deletion mutants are sensitive to at least one ROS, but no one oxidant is representative of 'oxidative stress' despite the widespread use of a single compound such as H(2)O(2). This has major implications for studies of pathological situations. Cells have a range of mechanisms for maintaining resistance that involves either induction or repression of many genes and extensive remodeling of the transcriptome. Cells have constitutive defense systems that are largely unique to each oxidant, but overlapping, inducible repair systems. The pattern of the transcriptional response to a particular ROS depends on its concentration, and 'classical' antioxidant systems that are induced by high concentrations of ROS can be repressed when cells adapt to low concentrations of ROS.

  20. A multi-paradigm language for reactive synthesis

    Directory of Open Access Journals (Sweden)

    Ioannis Filippidis


    Full Text Available This paper proposes a language for describing reactive synthesis problems that integrates imperative and declarative elements. The semantics is defined in terms of two-player turn-based infinite games with full information. Currently, synthesis tools accept linear temporal logic (LTL as input, but this description is less structured and does not facilitate the expression of sequential constraints. This motivates the use of a structured programming language to specify synthesis problems. Transition systems and guarded commands serve as imperative constructs, expressed in a syntax based on that of the modeling language Promela. The syntax allows defining which player controls data and control flow, and separating a program into assumptions and guarantees. These notions are necessary for input to game solvers. The integration of imperative and declarative paradigms allows using the paradigm that is most appropriate for expressing each requirement. The declarative part is expressed in the LTL fragment of generalized reactivity(1, which admits efficient synthesis algorithms, extended with past LTL. The implementation translates Promela to input for the Slugs synthesizer and is written in Python. The AMBA AHB bus case study is revisited and synthesized efficiently, identifying the need to reorder binary decision diagrams during strategy construction, in order to prevent the exponential blowup observed in previous work.

  1. Reactivity of copper(II)-alkylperoxo complexes. (United States)

    Tano, Tetsuro; Ertem, Mehmed Z; Yamaguchi, Satoru; Kunishita, Atsushi; Sugimoto, Hideki; Fujieda, Nobutaka; Ogura, Takashi; Cramer, Christopher J; Itoh, Shinobu


    Copper(II) complexes 1a and 1b, supported by tridentate ligand bpa [bis(2-pyridylmethyl)amine] and tetradentate ligand tpa [tris(2-pyridylmethyl)amine], respectively, react with cumene hydroperoxide (CmOOH) in the presence of triethylamine in CH(3)CN to provide the corresponding copper(II) cumylperoxo complexes 2a and 2b, the formation of which has been confirmed by resonance Raman and ESI-MS analyses using (18)O-labeled CmOOH. UV-vis and ESR spectra as well as DFT calculations indicate that 2a has a 5-coordinate square-pyramidal structure involving CmOO(-) at an equatorial position and one solvent molecule at an axial position at low temperature (-90 °C), whereas a 4-coordinate square-planar structure that has lost the axial solvent ligand is predominant at higher temperatures (above 0 °C). Complex 2b, on the other hand, has a typical trigonal bipyramidal structure with the tripodal tetradentate tpa ligand, where the cumylperoxo ligand occupies an axial position. Both cumylperoxo copper(II) complexes 2a and 2b are fairly stable at ambient temperature, but decompose at a higher temperature (60 °C) in CH(3)CN. Detailed product analyses and DFT studies indicate that the self-decomposition involves O-O bond homolytic cleavage of the peroxo moiety; concomitant hydrogen-atom abstraction from the solvent is partially involved. In the presence of 1,4-cyclohexadiene (CHD), the cumylperoxo complexes react smoothly at 30 °C to give benzene as one product. Detailed product analyses and DFT studies indicate that reaction with CHD involves concerted O-O bond homolytic cleavage and hydrogen-atom abstraction from the substrate, with the oxygen atom directly bonded to the copper(II) ion (proximal oxygen) involved in the C-H bond activation step.

  2. Synthesis and reactivity of compounds containing ruthenium-carbon, -nitrogen, and -oxygen bonds

    Energy Technology Data Exchange (ETDEWEB)

    Hartwig, J.F.


    The products and mechanisms of the thermal reactions of several complexes of the general structure (PMe{sub 3}){sub 4}Ru(X)(Y) and (DMPM){sub 2}Ru(X)(Y) where X and Y are hydride, aryl, and benzyl groups, have been investigated. The mechanism of decomposition depends critically on the structure of the complex and the medium in which the thermolysis is carried out. The alkyl hydride complexes are do not react with alkane solvent, but undergo C-H activation processes with aromatic solvents by several different mechanisms. Thermolysis of (PMe{sub 3}){sub 4}Ru(Ph)(Me) or (PMe{sub 3}){sub 4}Ru(Ph){sub 2} leads to the ruthenium benzyne complex (PMe{sub 3}){sub 4}Ru({eta}{sup 2}-C{sub 6}H{sub 4}) (1) by a mechanism which involves reversible dissociation of phosphine. In many ways its chemistry is analogous to that of early rather than late organo transition metal complexes. The synthesis, structure, variable temperature NMR spectroscopy and reactivity of ruthenium complexes containing aryloxide or arylamide ligands are reported. These complexes undergo cleavage of a P-C bond in coordinated trimethylphosphine, insertion of CO and CO{sub 2} and hydrogenolysis. Mechanistic studies on these reactions are described. The generation of a series of reactive ruthenium complexes of the general formula (PMe{sub 3}){sub 4}Ru(R)(enolate) is reported. Most of these enolates have been shown to bind to the ruthenium center through the oxygen atom. Two of the enolate complexes 8 and 9 exist in equilibrium between the O- and C-bound forms. The reactions of these compounds are reported, including reactions to form oxygen-containing metallacycles. The structure and reactivity of these ruthenium metallacycles is reported, including their thermal chemistry and reactivity toward protic acids, electrophiles, carbon monoxide, hydrogen and trimethylsilane. 243 refs., 10 tabs.

  3. Synthesis of functional nanocrystallites through reactive thermal plasma processing

    Directory of Open Access Journals (Sweden)

    Takamasa Ishigaki and Ji-Guang Li


    Full Text Available A method of synthesizing functional nanostructured powders through reactive thermal plasma processing has been developed. The synthesis of nanosized titanium oxide powders was performed by the oxidation of solid and liquid precursors. Quench gases, either injected from the shoulder of the reactor or injected counter to the plasma plume from the bottom of the reactor, were used to vary the quench rate, and therefore the particle size, of the resultant powders. The experimental results are well supported by numerical analysis on the effects of the quench gas on the flow pattern and temperature field of the thermal plasma as well as on the trajectory and temperature history of the particles. The plasma-synthesized TiO2 nanoparticles showed phase preferences different from those synthesized by conventional wet-chemical processes. Nanosized particles of high crystallinity and nonequilibrium chemical composition were formed in one step via reactive thermal plasma processing.

  4. Synthesis of Reactive Polymers for Acrolein Capture Using AGET ATRP. (United States)

    Beringer, Laura T; Li, Shaohua; Gilmore, Gary; Lister, John; Averick, Saadyah


    Acrolein is a toxic metabolite of the anticancer agent cyclophosphamide (CP). Current strategies to mitigate acrolein toxicity are insufficient, and in this brief article, we report the synthesis of well-defined low molecular weight block copolymers using activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) capable of reacting with the cytotoxic small molecule acrolein. Acrolein reactivity was introduced into the block copolymers via incorporation of either (a) aminooxy or (b) sulfhydryl groups. The cytoprotective effect of the polymers was compared to sodium 2-sulfanylethanesulfonate (mesna) the current gold standard for protection from CP urotoxicity, and we found that the polymers bearing sulfhydryl moieties demonstrated superior cytoprotective activity.

  5. Synthesis and crystal structure of binuclear copper(II) complex bridged by N-(2-hydroxyphenyl)-N'-[3-(diethylamino)propyl]oxamide: in vitro anticancer activity and reactivity toward DNA and protein. (United States)

    Gao, Yang; Li, Yan-Tuan; Wu, Zhi-Yong; Yan, Cui-Wei


    A new oxamido-bridged bicopper(II) complex, [Cu2(pdpox)(bpy)(CH3OH)](ClO4), where H3pdpox and bpy stand for N-(2-hydroxyphenyl)-N'-[3-(diethylamino)propyl]oxamide and 2,2'-bipyridine, respectively, has been synthesized and characterized by elemental analyses, molar conductivity measurements, infrared and electronic spectra studies, and X-ray single crystal diffraction. In the crystal structure, the pdpox(3-) ligand bridges two copper(II) ions as cisoid conformation. The inner copper(II) ion has a {N3O} square-planar coordination geometry, while the exo- one is in a {N2O3} square-pyramidal environment. There are two sets of interpenetrating two-dimensional hydrogen bonding networks parallel to the planes (2 1 0) and (21¯0), respectively, to form a three-dimensional supramolecular structure. The bicopper(II) complex exhibits cytotoxic activity against the SMMC7721 and A549 cell lines. The reactivity toward herring sperm DNA and bovine serum albumin revealed that the bicopper(II) complex can interact with the DNA by intercalation mode, and the complex binds to protein BSA responsible for quenching of tryptophan fluorescence by static quenching mechanism.

  6. Mechanochemical synthesis and reactivity of PbS nanocrystals (United States)

    Baláž, Peter; Pourghahramani, Parviz; Achimovičová, Marcela; Dutková, Erika; Kováč, Jaroslav; Šatka, Alexander; Jiang, Jiangzhong


    PbS nanocrystals using surfactant assisted mechanochemical synthesis have been prepared by co-milling of lead acetate (CH 3COO) 2Pb rad 3H 2O and sodium sulfide Na 2S rad 9H 2O. The methods of XRD, FE-SEM, TEM (HRTEM), UV-vis, specific surface area measurements as well as reactivity in acidic FeCl 3 media were used for the nanocrystals characterization. The XRD patterns confirmed the presence of galena PbS (JCPDS 5-592) whatever treatment conditions were applied. The strong observable peaks indicate the highly crystalline nature in formation of PbS nanostructures where preferential crystal growth in the (2 0 0) direction after addition of ethylenediamine (EDA), sodiumdodecylsulphate (SDS) and ethylendiaminetetraacetic disodium salt dihydrate (EDH) surfactants has been observed. The surface weighted crystallite sizes 3, 8, 11 and 19 nm have been calculated from XRD data using the Warren-Averbach method for surfactant-free and/or EDA, SDS and EDH surfactants assisted mechanochemical synthesis. The leaching rate of galena PbS in acidic FeCl 3 solution has been studied. The dependence of PbS nanocrystals reactivity on preferential growth parameter is documented. The highest value of the specific rate constant of leaching, k0/ SA has been obtained for the mechanochemically synthesized PbS in presence of EDH surfactant.

  7. Heavy Grignard Reagents: Synthesis, Physical and Structural Properties, Chemical Behavior, and Reactivity. (United States)

    Westerhausen, Matthias; Koch, Alexander; Görls, Helmar; Krieck, Sven


    The Grignard reaction offers a straight forward atom-economic synthesis of organomagnesium halides, which undergo redistribution reactions (Schlenk equilibrium) yielding diorganylmagnesium and magnesium dihalides. The homologous organocalcium complexes (heavy Grignard reagents) gained interest only quite recently owing to several reasons. The discrepancy between the inertness of this heavy alkaline earth metal and the enormous reactivity of its organometallics hampered a vast and timely development after the first investigation more than 100 years ago. In this overview the synthesis of organocalcium reagents is described as is the durability in ethereal solvents. Aryl-, alkenyl-, and alkylcalcium halides are prepared by direct synthesis. Characteristic structural features and NMR parameters are discussed. Ligand redistribution reactions can be performed by addition of potassium tert-butanolate to ethereal solutions of arylcalcium iodides yielding soluble diarylcalcium, whereas sparingly soluble potassium iodide and calcium bis(tert-butanolate) precipitate. Furthermore, reactivity studies with respect to metalation and addition to unsaturated organic compounds and metal-based Lewis acids, leading to the formation of heterobimetallic complexes, are presented. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. NH-type of chiral Ni(II) complexes of glycine Schiff base: design, structural evaluation, reactivity and synthetic applications. (United States)

    Bergagnini, Mackenzie; Fukushi, Kazunobu; Han, Jianlin; Shibata, Norio; Roussel, Christian; Ellis, Trevor K; Aceña, José Luis; Soloshonok, Vadim A


    The work being reported here deals with the design of a new type of "N-H" Ni(II) complexes of glycine Schiff bases and study general aspects of their reactivity. It was confirmed that the presence of NH function in these Ni(II) complexes does not interfere with the homologation of the glycine residue, rendering these derivatives of high synthetic value for the general synthesis of α-amino acids. In particular, the practical application of these NH-type complexes was demonstrated by asymmetric synthesis of various β-substituted pyroglutamic acids via Michael addition reactions with chiral Michael acceptors.

  9. Process Improvement of Reactive Dye Synthesis Using Six Sigma Concept (United States)

    Suwanich, Thanapat; Chutima, Parames


    This research focuses on the problem occurred in the reactive dye synthesis process of a global manufacturer in Thailand which producing various chemicals for reactive dye products to supply global industries such as chemicals, textiles and garments. The product named “Reactive Blue Base” is selected in this study because it has highest demand and the current chemical yield shows a high variation, i.e. yield variation of 90.4% - 99.1% (S.D. = 2.405 and Cpk = -0.08) and average yield is 94.5% (lower than the 95% standard set by the company). The Six Sigma concept is applied aiming at increasing yield and reducing variation of this process. This approach is suitable since it provides a systematic guideline with five improvement phases (DMAIC) to effectively tackle the problem and find the appropriate parameter settings of the process. Under the new parameter settings, the process yield variation is reduced to range between 96.5% - 98.5% (S.D. = 0.525 and Cpk = 1.83) and the average yield is increased to 97.5% (higher than the 95% standard set by the company).

  10. 2-(2'-Pyridyl)-4,6-diphenylphosphinine versus 2-(2'-pyridyl)-4,6-diphenylpyridine: synthesis, characterization, and reactivity of cationic Rh(III) and Ir(III) complexes based on aromatic phosphorus heterocycles. (United States)

    de Krom, Iris; Broeckx, Leen E E; Lutz, Martin; Müller, Christian


    The bidentate P,N hybrid ligand 1 allows access for the first time to novel cationic phosphinine-based Rh(III) and Ir(III) complexes, broadening significantly the scope of low-coordinate aromatic phosphorus heterocycles for potential applications. The coordination chemistry of 1 towards Rh(III) and Ir(III) was investigated and compared with the analogous 2,2'-bipyridine derivative, 2-(2'-pyridyl)-4,6-diphenylpyridine (2), which showed significant differences. The molecular structures of [RhCl(Cp*)(1)]Cl and [IrCl(Cp*)(1)]Cl (Cp*=pentamethylcyclopentadienyl) were determined by means of X-ray diffraction and confirm the mononuclear nature of the λ(3) -phosphinine-Rh(III) and Ir(III) complexes. In contrast, a different reactivity and coordination behavior was found for the nitrogen analogue 2, especially towards Rh(III) as a bimetallic ion pair [RhCl(Cp*)(2)](+) [RhCl3 (Cp*)](-) is formed rather than a mononuclear coordination compound. [RhCl(Cp*)(1)]Cl and [IrCl(Cp*)(1)]Cl react with water regio- and diastereoselectively at the external PC double bond, leading exclusively to the anti-addition products [MCl(Cp*)(1H⋅OH)]Cl as confirmed by X-ray crystal-structure determination.

  11. Pd(II complexes of acetylcholinesterase reactivator obidoxime

    Directory of Open Access Journals (Sweden)

    Nedzhib Ahmed


    Full Text Available The ability of the acetylcholinesterase reactivator obidoxime (H2L2+ to bind palladium(II cations was evaluated spectrophotometrically at different reaction conditions (pH, reaction time, metal-to-ligand molar ratio. The results showed that immediately after mixing the reagents, pH 7.4, complex species of composition [PdHL]3+ existed predominantly with a value of conditional stability constant lgβ'=6.52. The reaction was completed within 24 hours affording the formation of species [Pd2L]4+ with significantly increased stability (lgβ'=9.34. The spectral data suggest that obidoxime coordinates metal(II ions through the oximate functional groups. The in vitro reactivation assay of paraoxon-inhibited rat brain acetylcholinesterase revealed that the new complex species were much less active than the non-coordinated obidoxime. The lack of reactivation ability could be explained by the considerable stability of complexes in solution as well as by the deprotonation of oxime groups essential for recovery of the enzymatic activity.

  12. Synthesis of titanium carbide by induction plasma reactive spray

    Institute of Scientific and Technical Information of China (English)

    JIANG Xian-Liang(蒋显亮); M.Boulos


    A novel method capable of sufficient mixing of titanium powder and methane of carbon source was developed in the synthesis of titanium carbide by induction plasma reactive spray. X-ray diffraction analysis, optical microscopy, scanning electron microscopy, and microhardness test were used to characterize the spray-formed deposit.The experimental results show that both primary carburization of the titanium particles inside the plasma flame and secondary carburization of the growing deposit on high temperature substrate contribute to the forming of titanium carbide. The transitional phase of TiC1-x has the same crystal structure as TiC, but has a slightly low lattice constant. The deposit consists of fine grain structure and large grain structure. The fine grain structure, harder than large grain structure, shows grain boundary fracture.

  13. Reactive Spark Plasma Sintering: Successes and Challenges of Nanomaterial Synthesis

    Directory of Open Access Journals (Sweden)

    Dina V. Dudina


    Full Text Available Spark plasma sintering (SPS, initially developed as an advanced sintering technique for consolidating nanopowders into nanostructured bulk materials, has been recently looked at in much broader perspective and gained a strong reputation of a versatile method of solid state processing of metals, ceramics, and composites. The powders in the SPS-dies experience the action of pulsed electric current and uniaxial pressure; they are heated at very high rates unachievable in furnace heating and sintered within shorter times and at lower temperatures than in conventional methods. The principle of SPS and convenient design of the facilities make it attractive for conducting solid state synthesis. In this paper, based on our own results and the literature data, we analyze the microstructure formation of the products of chemical reactions occurring in the SPS in an attempt to formulate the requirements to the microstructure parameters of reactant mixtures and SPS conditions that should be fulfilled in order to produce a nanostructured material. We present successful syntheses of nanostructured ceramics and metal matrix composite with nanosized reinforcements in terms of microstructure stability and attractive properties of the materials and discuss the challenges of making a dense nanostructured material when reaction and densification do not coincide during the SPS. In the final part of the paper, we provide an outlook on the further uses of reactive SPS in the synthesis of nanostructured materials.

  14. Synthesis and reactivity of fluoro complexes: Part 2. Rhodium(I) fluoro complexes with alkene and phosphine ligands. Synthesis of the first isolated rhodium(I) bifluoride complexes. Structure of [Rh3(mu3-OH)2(COD)(3)](HF2) by X-ray powder diffraction. (United States)

    Vicente, José; Gil-Rubio, Juan; Bautista, Delia; Sironi, Angelo; Masciocchi, Norberto


    The reaction between [Rh(mu-OH)(COD)](2) (COD = 1,5-cyclooctadiene) and 73% HF in THF gives [Rh(3)(mu(3)-OH)(2)(COD)(3)](HF(2)) (1). Its crystal structure, determined by ab initio X-ray powder diffraction methods (from conventional laboratory data), contains complex trimetallic cations linked together in 1D chains by a mu(3)-OH...F-H-F...HO-mu(3) sequence of strong hydrogen bonds. The complex [Rh(mu-F)(COE)(2)](2) (COE = cyclooctene; 2), prepared by reacting [Rh(mu-OH)(COE)(2)](2) with NEt(3).3HF (3:2), has been characterized. Complex 1 reacts with PR(3) (1:3) to give [RhF(COD)(PR(3))] [R = Ph (3), C(6)H(4)OMe-4 (4), (i)Pr (5), Cy (6)] that can be prepared directly by reacting [Rh(mu-OH)(COD)](2) with 73% HF and PR(3) (1:2:2). The reactions of 1 with PPh(3) or Et(3)P have been studied by NMR spectroscopy at different molar ratios. Complexes [RhF(PEt(3))(3)] (7), [RhF(COD)(PEt(3))] (8), and [RhF(PPh(3))(3)] (9) have been detected. The complex [Rh(F)(NBD)(iPr(3)P)] (NBD = norbornadiene; 10) was prepared by the sequential treatment of [Rh(mu-OMe)(NBD)](2) with 1 equiv of NEt(3).3HF and (i)Pr(3)P. The first isolated bifluoride rhodium(I) complexes [Rh(FHF)(COD)(PR(3))] [R = Ph (11), (i)Pr (12), Cy (13)], obtained by reacting fluoro complexes 3, 5, and 6 with NEt(3).3HF (3:1), have been characterized. The crystal structures of 3 and 11 have been determined.

  15. Completing the complex Poynting theorem: Conservation of reactive energy in reactive time

    CERN Document Server

    Kaiser, Gerald


    The complex Poynting theorem is extended canonically to a time-scale domain $(t, s)$ by replacing the phasors of time-harmonic fields by the analytic signals $X(r, t+is)$ of fields $X(r,t)$ with general time dependence. The imaginary time $s>0$ is shown to play the role of a time resolution scale, and the extended Poynting theorem splits into two conservation laws: its real part gives the conservation in $t$ of the scale-averaged active energy at fixed $s$, and its imaginary part gives the conservation in $s$ of the scale-averaged reactive energy at fixed $t$. At coarse scales (large $s$, slow time), where the system reduces to the circuit level, this may have applications to the theory of electric power transmission and conditioning. At fine scales (small $s$, fast time) it describes reactive energy dynamics in radiating systems.

  16. Synthesis of Resins with Chiral Salen Complexes

    Institute of Scientific and Technical Information of China (English)


    @@ The enormous growth in the use of polymer resin supports in solid phase combinatorial synthesis, and related methodologies, has re-stimulated interest in the area of polymer-supported transition metal complex catalyst .The recently developed chiral salen-based for the enantioselective ring opening of meso epoxides and kinetic resolution of terminal epoxides are appealing candidates for immobilization on solid support. The catalysts are reading prepare from inexpensive components, and are amenable to modification for attachment to a solid support.

  17. Solution-phase synthesis of inorganic nanostructures by chemical transformation from reactive templates

    Institute of Scientific and Technical Information of China (English)


    The solution-phase synthesis by chemical transformation from reactive templates has proved to be very effective in morphology-controlled synthesis of inorganic nanostructures. This review paper summarizes the recent progress in solution-phase synthesis of one-dimensional and hollow inorganic nanostructures via reactive templates, focusing on the approaches developed in our lab. The formation mechanisms based on reactive templates are discussed in depth to show the general concepts for the preparation processes. An outlook on the future development in this area is also presented.

  18. Phthalides: Distribution in Nature, Chemical Reactivity, Synthesis, and Biological Activity. (United States)

    León, Alejandra; Del-Ángel, Mayela; Ávila, José Luis; Delgado, Guillermo

    oxidation, reduction, addition, elimination, and cycloaddition reactions, and treatments with Lewis acids of (Z)-ligustilide have afforded linear dimers. Some intramolecular condensations and differentiated cyclizations of the dimeric phthalides have been carried out, providing evidences for the particular chemical reactivity of these compounds.Several structural modifications of phthalides have been carried out subjecting them to microbial transformations by different species of bacteria, fungi and algae, and these included resolutions of racemic mixtures and oxidations, among others.The [π4s + π2s] and [π2s + π2s] cycloadditions of (Z)-ligustilide for the synthesis of dimeric phthalides have been reported, and different approaches involving cyclizations, Alder-Rickert reactions, Sharpless asymmetric hydroxylations, or Grignard additions have been used for the synthesis of monomeric phthalides. The use of phthalides as building blocks for divergent oriented synthesis has been proven.Many of the naturally occurring phthalides display different biological activities including antibacterial, antifungal, insecticidal, cytotoxic, and anti-inflammatory effects, among many others, with a considerable recent research on the topic. In the case of compounds isolated from the Apiaceae, the bioactivities correlate with the traditional medicinal uses of the natural sources. Some monomeric phthalides have shown their ability to attenuate certain neurological diseases, including stroke, Alzheimer's and Parkinson's diseases.The present contribution covers the distribution of phthalides in nature and the findings in the structural diversity, chemical reactivity, biotransformations, syntheses, and bioactivity of natural and semisynthetic phthalides.

  19. Microwave-Assisted Functionalization of Carbon Nanotubes and Reactive Synthesis of Nanocomposites Project (United States)

    National Aeronautics and Space Administration — The Offerers will build on their recent innovation of a microwave-induced route to the rapid functionalization, solubilization and reactive synthesis of carbon...

  20. Synthesis, Reactivity and Stability of Aryl Halide Protecting Groups towards Di-Substituted Pyridines

    Directory of Open Access Journals (Sweden)

    Ptoton Mnangat Brian


    Full Text Available This paper reports the synthesis and reactivity of different Benzyl derivative protecting groups. The synthesis and stability of Benzyl halides, 4-methoxybenzyl halides, 3,5-dimethoxybenzyl halides, 3,4-dimethoxybenzyl halides, 3,4,5-trimethoxybenzyl halide protecting groups and their reactivity towards nitrogen atom of a di-substituted pyridine ring in formation of pyridinium salts is also reported.

  1. Synthesis of Resins with Chiral Salen Complexes

    Institute of Scientific and Technical Information of China (English)

    WANG; YunPu


    The enormous growth in the use of polymer resin supports in solid phase combinatorial synthesis, and related methodologies, has re-stimulated interest in the area of polymer-supported transition metal complex catalyst .The recently developed chiral salen-based for the enantioselective ring opening of meso epoxides and kinetic resolution of terminal epoxides are appealing candidates for immobilization on solid support. The catalysts are reading prepare from inexpensive components, and are amenable to modification for attachment to a solid support.  ……

  2. Mitochondrial alpha-ketoglutarate dehydrogenase complex generates reactive oxygen species. (United States)

    Starkov, Anatoly A; Fiskum, Gary; Chinopoulos, Christos; Lorenzo, Beverly J; Browne, Susan E; Patel, Mulchand S; Beal, M Flint


    Mitochondria-produced reactive oxygen species (ROS) are thought to contribute to cell death caused by a multitude of pathological conditions. The molecular sites of mitochondrial ROS production are not well established but are generally thought to be located in complex I and complex III of the electron transport chain. We measured H(2)O(2) production, respiration, and NADPH reduction level in rat brain mitochondria oxidizing a variety of respiratory substrates. Under conditions of maximum respiration induced with either ADP or carbonyl cyanide p-trifluoromethoxyphenylhydrazone,alpha-ketoglutarate supported the highest rate of H(2)O(2) production. In the absence of ADP or in the presence of rotenone, H(2)O(2) production rates correlated with the reduction level of mitochondrial NADPH with various substrates, with the exception of alpha-ketoglutarate. Isolated mitochondrial alpha-ketoglutarate dehydrogenase (KGDHC) and pyruvate dehydrogenase (PDHC) complexes produced superoxide and H(2)O(2). NAD(+) inhibited ROS production by the isolated enzymes and by permeabilized mitochondria. We also measured H(2)O(2) production by brain mitochondria isolated from heterozygous knock-out mice deficient in dihydrolipoyl dehydrogenase (Dld). Although this enzyme is a part of both KGDHC and PDHC, there was greater impairment of KGDHC activity in Dld-deficient mitochondria. These mitochondria also produced significantly less H(2)O(2) than mitochondria isolated from their littermate wild-type mice. The data strongly indicate that KGDHC is a primary site of ROS production in normally functioning mitochondria.

  3. Photo-reactive charge trapping memory based on lanthanide complex. (United States)

    Zhuang, Jiaqing; Lo, Wai-Sum; Zhou, Li; Sun, Qi-Jun; Chan, Chi-Fai; Zhou, Ye; Han, Su-Ting; Yan, Yan; Wong, Wing-Tak; Wong, Ka-Leung; Roy, V A L


    Traditional utilization of photo-induced excitons is popularly but restricted in the fields of photovoltaic devices as well as photodetectors, and efforts on broadening its function have always been attempted. However, rare reports are available on organic field effect transistor (OFET) memory employing photo-induced charges. Here, we demonstrate an OFET memory containing a novel organic lanthanide complex Eu(tta)3ppta (Eu(tta)3 = Europium(III) thenoyltrifluoroacetonate, ppta = 2-phenyl-4,6-bis(pyrazol-1-yl)-1,3,5-triazine), in which the photo-induced charges can be successfully trapped and detrapped. The luminescent complex emits intense red emission upon ultraviolet (UV) light excitation and serves as a trapping element of holes injected from the pentacene semiconductor layer. Memory window can be significantly enlarged by light-assisted programming and erasing procedures, during which the photo-induced excitons in the semiconductor layer are separated by voltage bias. The enhancement of memory window is attributed to the increasing number of photo-induced excitons by the UV light. The charges are stored in this luminescent complex for at least 10(4) s after withdrawing voltage bias. The present study on photo-assisted novel memory may motivate the research on a new type of light tunable charge trapping photo-reactive memory devices.

  4. Gold(I)-selenolate complexes: Synthesis, characterization and ligand exchange reactions

    Indian Academy of Sciences (India)

    Krishna P Bhabak; Govindasamy Mugesh


    In this paper, the synthesis and characterization of some imidazole-based gold-selenolates are described. This study indicates that the nature of selenolate plays an important role in ligand exchange reactions in gold(I) selenolates. Furthermore, the reactivity of imidazole-based gold(I) selenolates toward nucleophiles such as selenols and phosphines is strikingly different from that of the ,-dimethylaminobenzylamine-based gold(I) complexes. The presence of Se$\\cdots$N non-bonded interactions in ,-dimethylaminobenzylamine-based gold(I) complexes modulates the reactivity of Au(I) centre towards incoming nucleophiles.

  5. Changes in mitochondrial reactive oxygen species synthesis during differentiation of skeletal muscle cells. (United States)

    Malinska, Dominika; Kudin, Alexei P; Bejtka, Malgorzata; Kunz, Wolfram S


    Myogenesis is accompanied by an intensive metabolic remodeling. We investigated the mitochondrial reactive oxygen species (ROS) generation at different levels of skeletal muscle differentiation: in C2C12 myoblasts, in C2C12 myotubes and in adult mouse skeletal muscle. Differentiation was accompanied by an increase in mitochondrial content and respiratory chain activity. The detected ROS production levels correlated with mitochondrial content, being the lowest in the myoblasts. Unlike the adult skeletal muscle, myoblast ROS production was significantly stimulated by the complex I inhibitor rotenone. Our results show that mitochondria are an important ROS source in skeletal muscle cells. The substantial changes in mitochondrial ROS synthesis during skeletal muscle differentiation can be explained by intensive bioenergetic remodeling.

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


    Pike, Sebastian D.; Weller, Andrew S.


    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/catalys...

  7. Synthesis, Structure and Reactivity of Molecules Attached to Electrode Surfaces. (United States)


    Structure and Reactivity of Molecules Attached to Electrode Surfaces", AFOSR #81-0149 III. REPORTING PERIOD: April 15, 1981 through April 14, 1985 IV...Adsorption .... ............... 17 9. Effect of Surface Roughness on Adsorbate Orientation and Reactivity . 20 10. Ordered/ Disordered Packing in Chemisorbed... reactivity only when present in the edge-pendant orientation. Clearly, molecular orientation (i.e., mode of +. .4 o,, -12- attachment to the surface) is a

  8. Synthesis of Functional Polyethylene Copolymers via Reactive Monomer

    Institute of Scientific and Technical Information of China (English)

    Hua-yi Li; Shu-qing Zhang; Ling-zhi Wang; You-liang Hu


    @@ 1Introduction Polyolefins are used widely due to their good performance and low price, but the poor compatibility and adhesion with other materials limits their applications in broader areas. Reactive monomer approach is effective to synthesize functional polyolefins[1]. In this case, olefin is copolymerized with a reactive comonomer to produce reactive intermediary which is then converted to functional group or initiator to initiate graft-from polymerization of polar monomer.

  9. Ru(0) and Ru(II) nitrosyl pincer complexes: structure, reactivity, and catalytic activity. (United States)

    Fogler, Eran; Iron, Mark A; Zhang, Jing; Ben-David, Yehoshoa; Diskin-Posner, Yael; Leitus, Gregory; Shimon, Linda J W; Milstein, David


    Despite considerable interest in ruthenium carbonyl pincer complexes and their substantial catalytic activity, there has been relatively little study of the isoelectronic ruthenium nitrosyl complexes. Here we describe the synthesis and reactivity of several complexes of this type as well as the catalytic activity of complex 6. Reaction of the PNP ligand (PNP = 2,6-bis((t)Bu2PCH2)pyridine) with RuCl3(NO)(PPh3)2 yielded the Ru(II) complex 3. Chloride displacement by BAr(F-) (BAr(F-) = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) gave the crystallographicaly characterized, linear NO Ru(II) complex 4, which upon treatment with NaBEt3H yielded the Ru(0) complexes 5. The crystallographically characterized Ru(0) square planar complex 5·BF4 bears a linear NO ligand located trans to the pyridilic nitrogen. Further treatment of 5·BF4 with excess LiOH gave the crystallographicaly characterized Ru(0) square planar, linear NO complex 6. Complex 6 catalyzes the dehydrogenative coupling of alcohols to esters, reaching full conversion under air or under argon. Reaction of the PNN ligand (PNN = 2-((t)Bu2PCH2)-6-(Et2NCH2)pyridine) with RuCl3(NO)(H2O)2 in ethanol gave an equilibrium mixture of isomers 7a and 7b. Further treatment of 7a + 7b with 2 equivalent of sodium isopropoxide gave the crystallographicaly characterized, bent-nitrosyl, square pyramidal Ru(II) complex 8. Complex 8 was also synthesized by reaction of PNN with RuCl3(NO)(H2O)2 and Et3N in ethanol. Reaction of the "long arm" PN(2)N ligand (PN(2)N = 2-((t)Bu2PCH2-)-6-(Et2NCH2CH2)pyridine) with RuCl3(NO)(H2O)2 in ethanol gave complex 9, which upon treatment with 2 equiv of sodium isopropoxide gave complex 10. Complex 10 was also synthesized directly by reaction of PN(2)N with RuCl3(NO)(H2O)2 and a base in ethanol. A noteworthy aspect of these nitrosyl complexes is their preference for the Ru(0) oxidization state over Ru(II). This preference is observed with both aromatized and dearomatized pincer ligands, in

  10. Complex Ancestries of Isoprenoid Synthesis in Dinoflagellates. (United States)

    Bentlage, Bastian; Rogers, Travis S; Bachvaroff, Tsvetan R; Delwiche, Charles F


    Isoprenoid metabolism occupies a central position in the anabolic metabolism of all living cells. In plastid-bearing organisms, two pathways may be present for de novo isoprenoid synthesis, the cytosolic mevalonate pathway (MVA) and nuclear-encoded, plastid-targeted nonmevalonate pathway (DOXP). Using transcriptomic data we find that dinoflagellates apparently make exclusive use of the DOXP pathway. Using phylogenetic analyses of all DOXP genes we inferred the evolutionary origins of DOXP genes in dinoflagellates. Plastid replacements led to a DOXP pathway of multiple evolutionary origins. Dinoflagellates commonly referred to as dinotoms due to their relatively recent acquisition of a diatom plastid, express two completely redundant DOXP pathways. Dinoflagellates with a tertiary plastid of haptophyte origin, by contrast, express a hybrid pathway of dual evolutionary origin. Here, changes in the targeting motif of signal/transit peptide likely allow for targeting the new plastid by the proteins of core isoprenoid metabolism proteins. Parasitic dinoflagellates of the Amoebophyra species complex appear to have lost the DOXP pathway, suggesting that they may rely on their host for sterol synthesis.

  11. Asymmetric synthesis of pyrazoles and pyrazolones employing the reactivity of pyrazolin-5-one derivatives. (United States)

    Chauhan, Pankaj; Mahajan, Suruchi; Enders, Dieter


    Due to the frequent occurrence of the pyrazole core in many important naturally occurring and synthetic molecules, tremendous efforts have been made for their synthesis. The pyrazolin-5-one derivatives have emerged as the most effective substrates for the synthesis of useful pyrazoles and their corresponding pyrazolone derivatives. Recently, the reactivity of pyrazolin-5-ones has been used for the asymmetric synthesis of highly functionalised pyrazole and pyrazolone derivatives by employing organo- and metal-catalysts. This feature article focuses on the progress in the catalytic asymmetric synthesis of pyrazoles and pyrazolones using pyrazolin-5-one derivatives.

  12. Colloidal stability and chemical reactivity of complex colloids containing Fe3+

    NARCIS (Netherlands)

    van Leeuwen, Y.M.|info:eu-repo/dai/nl/314850139; Velikov, K. P.; Kegel, W.K.|info:eu-repo/dai/nl/113729464


    The reactivity of iron contained within insoluble colloidal metal-pyrophosphate salts was determined and compared to the reactivity of a soluble iron salt (FeCl3). As a model system for the reactivity of iron in food products, the formation of an iron–polyphenol complex was followed with

  13. Bipyrimidine ruthenium(II) arene complexes: structure, reactivity and cytotoxicity. (United States)

    Betanzos-Lara, Soledad; Novakova, Olga; Deeth, Robert J; Pizarro, Ana M; Clarkson, Guy J; Liskova, Barbora; Brabec, Viktor; Sadler, Peter J; Habtemariam, Abraha


    The synthesis and characterization of complexes [(η(6)-arene)Ru(N,N')X][PF(6)], where arene is para-cymene (p-cym), biphenyl (bip), ethyl benzoate (etb), hexamethylbenzene (hmb), indane (ind) or 1,2,3,4-tetrahydronaphthalene (thn), N,N' is 2,2'-bipyrimidine (bpm) and X is Cl, Br or I, are reported, including the X-ray crystal structures of [(η(6)-p-cym)Ru(bpm)I][PF(6)], [(η(6)-bip)Ru(bpm)Cl][PF(6)], [(η(6)-bip)Ru(bpm)I][PF(6)] and [(η(6)-etb)Ru(bpm)Cl][PF(6)]. Complexes in which N,N' is 1,10-phenanthroline (phen), 1,10-phenanthroline-5,6-dione or 4,7-diphenyl-1,10-phenanthroline (bathophen) were studied for comparison. The Ru(II) arene complexes undergo ligand-exchange reactions in aqueous solution at 310 K; their half-lives for hydrolysis range from 14 to 715 min. Density functional theory calculations on [(η(6)-p-cym)Ru(bpm)Cl][PF(6)], [(η(6)-p-cym)Ru(bpm)Br][PF(6)], [(η(6)-p-cym)Ru(bpm)I][PF(6)], [(η(6)-bip)Ru(bpm)Cl][PF(6)], [(η(6)-bip)Ru(bpm)Br][PF(6)] and [(η(6)-bip)Ru(bpm)I][PF(6)] suggest that aquation occurs via an associative pathway and that the reaction is thermodynamically favourable when the leaving ligand is I > Br ≈ Cl. pK (a)* values for the aqua adducts of the complexes range from 6.9 to 7.32. A binding preference for 9-ethylguanine (9-EtG) compared with 9-ethyladenine (9-EtA) was observed for [(η(6)-p-cym)Ru(bpm)Cl][PF(6)], [(η(6)-hmb)Ru(bpm)Cl](+), [(η(6)-ind)Ru(bpm)Cl](+), [(η(6)-thn)Ru(bpm)Cl](+), [(η(6)-p-cym)Ru(phen)Cl](+) and [(η(6)-p-cym)Ru(bathophen)Cl](+) in aqueous solution at 310 K. The X-ray crystal structure of the guanine complex [(η(6)-p-cym)Ru(bpm)(9-EtG-N7)][PF(6)](2) shows multiple hydrogen bonding. Density functional theory calculations show that the 9-EtG adducts of all complexes are thermodynamically preferred compared with those of 9-EtA. However, the bmp complexes are inactive towards A2780 human ovarian cancer cells. Calf thymus DNA interactions for [(η(6)-p-cym)Ru(bpm)Cl][PF(6)] and [(η(6)-p

  14. Synthesis of complex fluorides for optical applications (United States)

    Stepleton, Seth Eugene

    size were produced, and many spectroscopically active rare earth elements were doped into both hosts. A novel synthetic pathway to the hexagonal beta-RbGd3F 10, was discovered which led to the novel compound, beta-RbHo 3F10. The hydrothermal synthesis of hexafluoroelpasolites and lanthanide sesquioxides is also investigated. The hydrothermal synthesis described in this work has furthered the study of complex fluorides for optical applications. Novel synthetic pathways were discovered to known optical materials. Novel materials were also discovered. 1Takashima, M. In Advanced Inorganic Fluorides: Synthesis, Characterization and Applications, Nakajima, T.; Zemva, B.; Tressaud, A.; Elsevier: Amsterdam, The Netherlands, 2000, 176. 2Fouassier, C. In Advanced Inorganic Fluorides: Synthesis, Characterization and Applications, Nakajima, T.; Zemva, B.; Tressaud, A.; Elsevier: Amsterdam, The Netherlands, 2000, 316. 3Capper, P. In Bulk Crystal Growth of Electronic, Optical and Optoelectronic Materials, John Wiley and Sons: Great Britain, 2005. 4Solans, X.; Gonzalez-Silgo, C.; Calvet, T.; Ruiz-Perez, C.; Martinez-Sarrion, M. L.; Mestres, L. Phys. Rev. B 1998, 57(9), 5122-5125. 5Azorin-Nieto, J.; Khaidukov, N.M.; Sanchez-Rodriguez, A.; Azorin-Vega, J.C. Nuclear Instruments and Methods in Physics Research, 2007, B263, 36-40. 6Wang, D.; Min, Y.; Xia, S.; Makhov, V.N.; Khaidukov, N.M.; J.C. Krupa, J.C. Journal of Alloys and Compounds, 2003, 361, 294-298.

  15. Synthesis and unexpected reactivity of [Ru(6 -cymene)Cl2 (PPh2 Cl)], leading to [Ru(6 -cymene)Cl2 (PPh2H)] and [Ru(6-cymene)Cl2 (PPh2OH)] complexes

    Indian Academy of Sciences (India)

    Arun Kumar Pandiakumar; Ashoka G Samuelson


    The reaction of [Ru(6-cymene)Cl2]2 and PPh2Cl in the ratio 1:2 gives a stable [Ru(6-cymene) Cl2(PPh2Cl)] complex. Attempts to make the cationic [Ru(6-cymene)Cl(PPh2Cl)2]Cl with excess PPh2Cl and higher temperatures led to adventitious hydrolysis and formation of [Ru(6-cymene)Cl2 (PPh2OH)]. Attempts to make a phosphinite complex by reacting [Ru(6-cymene)Cl2]2 with PPh2Cl in the presence of an alcohol results in the reduction of PPh2Cl to give [Ru(6-cymene)Cl2(PPh2H)] and the expected phosphinite. The yield of the hydride complex is highest when the alcohol is 1-phenyl-ethane-1,2-diol. All three half-sandwich complexes are characterized by X-ray crystallography. Surprisingly, the conversion of chlorodiphenylphosphine to diphenylphosphine is mediated by 1-phenyl-ethane-1,2-diol even in the absence of the ruthenium half-sandwich precursor.

  16. Lanthanide alkyl and silyl compounds: Synthesis, reactivity and catalysts for green

    Energy Technology Data Exchange (ETDEWEB)

    Pindwal, Aradhana [Iowa State Univ., Ames, IA (United States)


    The last few decades have witnessed enormous research in the field of organometallic lanthanide chemistry. Our research group has developed a few rare earth alkyl compounds containing tris(dimethylsilyl)methyl ligand and explored their reactivity. This thesis focusses on extending the study of lanthanide alkyl and silyl compounds to develop strategies for their synthesis and explore their reactivity and role as catalysts in processes such as hydrosilylation and cross-dehydrocoupling.

  17. Synthesis, structure, and reactivity of rhodium and iridium complexes of the chelating bis-sulfoxide tBuSOC2H4SOtBu. Selective O-H activation of 2-hydroxy-isopropyl-pyridine. (United States)

    Schaub, Thomas; Diskin-Posner, Yael; Radius, Udo; Milstein, David


    The chloro-bridged rhodium and iridium complexes [M2(BTSE)2Cl2] (M = Rh 1, Ir 2) bearing the chelating bis-sulfoxide tBuSOC2H4SOtBu (BTSE) were prepared by the reaction of [M2(COE)4Cl2] (M = Rh, Ir; COE = cyclooctene) with an excess of a racemic mixture of the ligand. The cationic compounds [M(BTSE)2][PF6] (M = Rh 3, Ir 4), bearing one S- and one O-bonded sulfoxide, were also obtained in good yields. The chloro-bridges in 2 can be cleaved with 2-methyl-6-pyridinemethanol and 2-aminomethyl pyridine, resulting in the iridium(I) complexes [Ir(BTSE)(Py)(Cl)] (Py = 2-methyl-6-pyridinemethanol 5, 2-aminomethyl-pyridine 6). In case of the bulky 2-hydroxy- isopropyl-pyridine, selective OH oxidative addition took place, forming the Ir(III)-hydride [Ir(BTSE)(2-isopropoxy-pyridine)(H)(Cl)] 7, with no competition from the six properly oriented C-H bonds. The cationic rhodium(I) and iridium(I) compounds [M(BTSE)(2-aminomethyl-pyridine)][X] (M = Rh 8, Ir 10), [Rh(BTSE)(2-hydroxy- isopropyl-pyridine)][X] 9(stabilized by intramolecular hydrogen bonding), [Ir(BTSE)(pyridine)2][PF6] 12, [Ir(BTSE)(alpha-picoline)2][PF6] 13, and [Rh(BTSE)(1,10-phenanthroline)][PF6] 14 were prepared either by chloride abstraction from the dimeric precursors or by replacement of the labile oxygen bonded sulfoxide in 3 or 4. Complex 14 exhibits a dimeric structure in the solid state by pi-pi stacking of the phenanthroline ligands.

  18. Design and synthesis of reactive separation systems. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Doherty, M.F.


    During the last decade there has been a rapid upturn in interest in reactive distillation. The chemical process industry recognizes the favorable economics of carrying out reaction simultaneously with distillation for certain classes of reacting systems, and many new processes have been built based on this technology. Interest is also increasing by academics and software vendors. Systematic design methods for reactive distillation systems have only recently begun to emerge. In this report we survey the available design techniques and point out the contributions made by our group at the University of Massachusetts.

  19. Chemical synthesis and biochemical reactivity of bacteriophage lambda PR promoter.



    By a combination of chemical and enzymatic methods, a 75 base pair DNA duplex containing the sequence of the lambda PR promoter including the OR1 and OR2 cI repressor binding sites was synthesized. The solid support phosphite triester procedure (Caruthers, M. H. et al., Cold Spring Harbor Symposia on Quantitative Biology XLVII, in press) was used for the synthesis of oligonucleotides comprising the sequence. We report here an adaptation of the method of DNA synthesis in test tubes. Assembly o...

  20. Synthesis and Reactivity of Aluminized Fluorinated Acrylic (AIFA) Nanocomposites (Postprint) (United States)


    REACTIVITY OF ALUMINIZED FLUORINATED ACRYLIC (ALFA) NANOCOMPOSITES (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...the nano Al throughout the material, the composite was compounded for 3 min in a DACA Instruments benchtop twin screw extruder at 150 C. The com

  1. Synthesis, structure, and reactivity of a stabilized phosphiranylium salt

    NARCIS (Netherlands)

    Jansen, H.; Läng, F. B.; Slootweg, J.C.; Ehlers, A.W.; Lutz, M.; Lammertsma, K.; Grützmacher, H.


    Phosphiranes with a three-membered PC2 ring have unique electronic properties.[1] Although their ring strain is smaller than that in cyclopropanes, they are highly reactive and display remarkable chemistry, such as [2+1] cycloreversions to olefins and phosphinidenes [R P],[2] cationic ring-opening p

  2. Synthesis and processing of composites by reactive metal penetration

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E.; Ewsuk, K.G. [Sandia National Laboratories, Albuquerque, NM (United States); Tomsia, A.P. [Pask Research and Engineering, Berkeley, CA (United States)] [and others


    Ceramic-metal composites are being developed because their high stiffness-to weight ratios, good fracture toughness, and variable electrical and thermal properties give them advantages over more conventional materials. However, because ceramic-metal composite components presently are more expensive than monolithic materials, improvements in processing are required to reduce manufacturing costs. Reactive metal penetration is a promising new method for making ceramic- and metal-matrix composites that has the advantage of being inherently a net-shape process. This technique, once fully developed, will provide another capability for manufacturing the advanced ceramic composites that are needed for many light-weight structural and wear applications. The lower densities of these composites lead directly to energy savings in use. Near-net-shape fabrication of composite parts should lead to additional savings because costly and energy intensive grinding and machining operations are significantly reduced, and the waste generated from such finishing operations is minimized. The goals of this research program are: (1) to identify feasible compositional systems for making composites by reactive metal penetration; (2) to understand the mechanism(s) of composite formation by reactive metal penetration; and (3) to learn how to control and optimize reactive metal penetration for economical production of composites and composite coatings.

  3. Synthesis and Properties of Reactive Interfacial Agents for Polycaprolactone-Starch Blends

    NARCIS (Netherlands)

    Sugih, Asaf K.; Drijfhout, Jan. P.; Picchioni, Francesco; Janssen, Leon P. B. M.; Heeres, Hero J.


    The synthesis of two reactive interfacial agents for starch-polycaprolactone (PCL) blends, PCL-g-glycidyl methacrylate (PCL-g-GMA) and PCL-g-diethyl maleate (PCL-g-DEM) is described. The compounds were prepared by reacting a low molecular weight PCL. (M(w) 3000) with GMA or DEM in the presence of be

  4. Photoluminescent silicon nanocrystals with chlorosilane surfaces - synthesis and reactivity (United States)

    Höhlein, Ignaz M. D.; Kehrle, Julian; Purkait, Tapas K.; Veinot, Jonathan G. C.; Rieger, Bernhard


    We present a new efficient two-step method to covalently functionalize hydride terminated silicon nanocrystals with nucleophiles. First a reactive chlorosilane layer was formed via diazonium salt initiated hydrosilylation of chlorodimethyl(vinyl)silane which was then reacted with alcohols, silanols and organolithium reagents. With organolithium compounds a side reaction is observed in which a direct functionalization of the silicon surface takes place.We present a new efficient two-step method to covalently functionalize hydride terminated silicon nanocrystals with nucleophiles. First a reactive chlorosilane layer was formed via diazonium salt initiated hydrosilylation of chlorodimethyl(vinyl)silane which was then reacted with alcohols, silanols and organolithium reagents. With organolithium compounds a side reaction is observed in which a direct functionalization of the silicon surface takes place. Electronic supplementary information (ESI) available: Detailed experimental procedures and additional NMR, PL, EDX, DLS and TEM data. See DOI: 10.1039/C4NR05888G

  5. Cerebrovascular Reactivity in Complex Diagnostics of Vertebrobasilar Insufficiency

    Directory of Open Access Journals (Sweden)

    Goydenko V. S.


    Full Text Available The article presents the results of the assessment of cerebrovascular reactivity parameters due to transcranial Doppler sonography in 104 patients (62 women and 42 men with spondilogenic vertebrobasilar insufficiency. Mean age of patients was 42.9±12.2 years. It was found that the assessment of cerebrovascular reactivity and type of response to functional loading tests allows to confirm vertebrobasilar stage insufficiency, to determine the activity of various regulatory mechanisms of compensation of cerebral circulation and adaptation reserve of the cerebral vascular system.

  6. Oxetanes: Recent Advances in Synthesis, Reactivity, and Medicinal Chemistry. (United States)

    Bull, James A; Croft, Rosemary A; Davis, Owen A; Doran, Robert; Morgan, Kate F


    The four-membered oxetane ring has been increasingly exploited for its contrasting behaviors: its influence on physicochemical properties as a stable motif in medicinal chemistry and its propensity to undergo ring-opening reactions as a synthetic intermediate. These applications have driven numerous studies into the synthesis of new oxetane derivatives. This review takes an overview of the literature for the synthesis of oxetane derivatives, concentrating on advances in the last five years up to the end of 2015. These methods are clustered by strategies for preparation of the ring and further derivatization of preformed oxetane-containing building blocks. Examples of the use of oxetanes in medicinal chemistry are reported, including a collation of oxetane derivatives appearing in recent patents for medicinal chemistry applications. Finally, examples of oxetane derivatives in ring-opening and ring-expansion reactions are described.

  7. A New Complex with Good Catalytic Properties in Asymmetric Synthesis of Cyclopropanecarboxylic Acids

    Institute of Scientific and Technical Information of China (English)

    CAI Ya; ZHENG He-Gen; XIN Xin-Quan


    @@ The chemistry of transition metal-sulfur clusters has attracted much attention recently owing to their relevance to certain biological and industrial catalyses, rich structural chemistry, and special reactive properties as well as potential application in nonlinear optical materials. [1~ 3] In this article, a new complex, WCu2S4 (dppf)2 [ dppf = 1, 1′bis(diphenylphosphino)ferrocene] was synthesized through solid state reaction, and it was found that this complex had good catalytic properties in asymmetric synthesis of cyclopropanecarboxylic acids.

  8. Synthesis and processing of composites by reactive metal penetration

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E.; Ewsuk, K.G. [Sandia National Labs., Albuquerque, NM (United States); Tomsia, A.P. [Pask Research and Engineering, Berkeley, CA (United States)] [and others


    Achieving better performance in commercial products and processes often is dependent on availability of new and improved materials. Ceramic-metal composites have advantages over more conventional materials because of their high stiffness-to-weight ratios, good fracture toughness, and because their electrical and thermal properties can be varied through control of their compositions and microstructures. However, ceramic composites will be more widely used only when their costs are competitive with other materials and when designers have more confidence in their reliability. Over the past four years reactive metal penetration has been shown to be a promising technique for making ceramic and metal-matrix composites to near-net-shape with control of both composition and microstructure. It appears that, with sufficient development, reactive metal penetration could be an economical process for manufacturing many of the advanced ceramic composites that are needed for light-weight structural and wear applications for transportation and energy conversion devices. Near-net-shape fabrication of parts is a significant advantage because costly and energy intensive grinding and machining operations are substantially reduced, and the waste generated from such finishing operations is minimized. The most promising compositions to date consist of Al and Al{sub 2}O{sub 3}; thus, these composites should be of particular interest to the aluminum industry. The goals of this ceramic-metal composite research and development program are: (1) to identify compositions favorable for making composites by reactive metal penetration; (2) to understand the mechanism(s) by which these composites are formed; (3) to control and optimize the process so that composites and composite coatings can be made economically; and (4) to apply R&D results to problems of interest to the aluminum industry.

  9. Synthesis and Characterization of Organotin Containing Copolymers: Reactivity Ratio Studies

    Directory of Open Access Journals (Sweden)

    Mohamed H. El-Newehy


    Full Text Available Organotin monomers containing dibutyltin groups – dibutyltin citraconate (DBTC as a new monomer and dibutyltin maleate (DBTM – were synthesized. Free radical copolymerizations of the organotin monomers with styrene (ST and butyl acrylate (BA were performed. The overall conversion was kept low (≤15% wt/wt for all studied samples and the copolymers composition was determined from tin analysis using the Gillman and Rosenberg method. The reactivity ratios were calculated from the copolymer composition using the Fineman-Ross (FR method. The synthesized monomers were characterized by elemental analysis, 1H-, 13C-NMR and FTIR spectroscopy.

  10. Synthesis, characterization and photophysical properties of ESIPT reactive triazine derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Kuplich, Marcelo D.; Grasel, Fabio S.; Campo, Leandra F.; Rodembusch, Fabiano S.; Stefani, Valter, E-mail: [Laboratorio de Novos Materiais Organicos. Instituto de Quimica. Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil)


    Four new reactive fluorescent triazine derivatives were obtained from nucleophilic aromatic substitution of cyanuric chloride. The compounds were characterized by infrared spectroscopy (IR), nuclear magnetic resonance ({sup 13}C and {sup 1}H NMR) and high resolution mass spectrometry (HRMS MALDI). UV-Vis and steady-state fluorescence (in solution and in solid state) spectroscopies were also applied to characterize the photophysical behavior. The dyes are fluorescent by an intramolecular proton transfer mechanism (ESIPT) in the blue-orange region, with a large Stokes shift between 6365-10290 cm-1. The fluorescent cyanuric derivatives could successfully react with cellulose fibers to give new fluorescent cellulosic materials. (author)

  11. Developing mononuclear copper-active-oxygen complexes relevant to reactive intermediates of biological oxidation reactions. (United States)

    Itoh, Shinobu


    Active-oxygen species generated on a copper complex play vital roles in several biological and chemical oxidation reactions. Recent attention has been focused on the reactive intermediates generated at the mononuclear copper active sites of copper monooxygenases such as dopamine β-monooxygenase (DβM), tyramine β-monooxygenase (TβM), peptidylglycine-α-hydroxylating monooxygenase (PHM), and polysaccharide monooxygenases (PMO). In a simple model system, reaction of O2 and a reduced copper(I) complex affords a mononuclear copper(II)-superoxide complex or a copper(III)-peroxide complex, and subsequent H(•) or e(-)/H(+) transfer, which gives a copper(II)-hydroperoxide complex. A more reactive species such as a copper(II)-oxyl radical type species could be generated via O-O bond cleavage of the peroxide complex. However, little had been explored about the chemical properties and reactivity of the mononuclear copper-active-oxygen complexes due to the lack of appropriate model compounds. Thus, a great deal of effort has recently been made to develop efficient ligands that can stabilize such reactive active-oxygen complexes in synthetic modeling studies. In this Account, I describe our recent achievements of the development of a mononuclear copper(II)-(end-on)superoxide complex using a simple tridentate ligand consisting of an eight-membered cyclic diamine with a pyridylethyl donor group. The superoxide complex exhibits a similar structure (four-coordinate tetrahedral geometry) and reactivity (aliphatic hydroxylation) to those of a proposed reactive intermediate of copper monooxygenases. Systematic studies based on the crystal structures of copper(I) and copper(II) complexes of the related tridentate supporting ligands have indicated that the rigid eight-membered cyclic diamine framework is crucial for controlling the geometry and the redox potential, which are prerequisites for the generation of such a unique mononuclear copper(II)-(end-on)superoxide complex

  12. Copper(I)-N-heterocyclic carbene (NHC) complexes : synthesis, characterisation and applications in synthesis and catalysis


    Santoro, Orlando


    The work described herein focuses on the synthesis and characterisation of copper(I) complexes bearing N-heterocyclic carbene (NHC) ligands, their use in catalysis as well as organometallic synthesis and related reaction mechanisms. Two classes of complexes were considered: neutral NHC-Cu(I) species and their cationic analogues. Concerning the former, initial efforts were focused on the development of a general and straightforward synthetic methodology towards complexes of the type [Cu(X)(...

  13. Reactive ion exchange synthesis of high pure nano-CeO2

    Institute of Scientific and Technical Information of China (English)

    ZHU Shao-min; FENG Ying-chun; WEN Yang; JIANG Yu-ling


    This paper presents a reactive ion exchange synthesis method of nano-CeO2 with positive cerium preexchanged ion exchange resin as precursor and (NH4)2CO3 as precipitant.The resultant precipitate was dried at 100 ℃ for 12 h and then was calcined at 500 K in air.The effects of ion exchange temperature and reaction time on the diameter of CeO2 particle were discussed.The TEM images show that the samples prepared with one step reactive ion exchange method are composed of nano-club with the length about 300 nm.

  14. Sterically demanding hetero-substituted [2]borametallocenophanes of group IV metals: synthesis, structure and reactivity. (United States)

    Braunschweig, Holger; Dörfler, Rainer; Mies, Jan; Oechsner, Andreas


    We report the synthesis and characterisation of unprecedented unstrained [2]diborametallocenophanes of zirconium and hafnium that bear the bulky octamethylfluorenyl (η(5)-C(29)H(36)) system, the proligands of which were pre-constructed by a two-step synthesis. The compounds were fully characterised by NMR spectroscopy, MALDI-TOF mass spectrometry and X-ray diffraction analysis. Typical reactivities relevant to olefin polymerisation such as methylation and chloride abstraction were also investigated. Finally, a sterically demanding bis(octamethylfluorenyl) metallocene was prepared.


    African Journals Online (AJOL)


    [RuCl(η6-p-cymene)(η2-dppm)][PF6] ruthenium complexes with C2O4(Me4N)2 in the ... electron donor pair ligands to the metal centre offers useful methods of access to an increasing ..... red-brown solid 7 in a poor yield of 17 % (Figure 6).

  16. Synthesis, characterization and properties of some organozinc hydride complexes

    NARCIS (Netherlands)

    Koning, A.J. de; Boersma, J.; Kerk, G.J.M. van der


    The synthesis and characterization of the monopyridine complexes of ethylzinc hydride and phenylzinc hydride are described. On treatment with TMED these complexes are converted into R2Zn3H4. TMED species through a combination of ligand-exchange and disproportionation. The formation of organozinc hyd

  17. Synthesis of Alumina Thin Films Using Reactive Magnetron Sputtering Method (United States)

    Angarita, G.; Palacio, C.; Trujillo, M.; Arroyave, M.


    Alumina (Al2O3) thin films were deposited on Si (100) by Magnetron Sputtering in reactive conditions between an aluminium target and oxygen 99.99% pure. The plasma was formed employing Argon with an R.F power of 100 W, the dwelling time was 3 hours. 4 samples were produced with temperatures between 350 and 400 ºC in the substrate by using an oxygen flow of 2 and 8 sccm, the remaining parameters of the process were fixed. The coatings and substrates were characterized using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Energy Dispersive Spectroscopy (EDS) in order to compare their properties before and after deposition. The films thicknesses were between 47 and 70 nm. The results show that at high oxygen flow the alumina structure prevails in the coatings while at lower oxygen flow only aluminum is deposited in the coatings. It was shown that the temperature increases grain size and roughness while decreasing the thicknesses of the coatings.

  18. Reactivity of carbides in synthesis of MgB 2 bulks (United States)

    Yamamoto, Akiyasu; Shimoyama, Jun-ichi; Ueda, Shinya; Horii, Shigeru; Kishio, Kohji


    The reactivity of various carbides (B4C, Al4C3, SiC, TiC, ZrC, NbC, Mo2C, HfC and WC) with magnesium and boron in synthesis of MgB2 was systematically studied. Decreases in the a-axis length and transition temperature were observed in all the carbide doped MgB2 bulks, reflecting a certain amount of carbon substituted for boron site in MgB2. The reactivity of each carbide estimated by the carbon content in MgB2 was found to be different depending on the chemical stability. Our results suggest that carbon content in MgB2 lattice can be controlled to its optimal doping level by adjusting synthesis conditions and selection of doping reagents.

  19. Synthesis and characterization of tantalum silsesquioxane complexes. (United States)

    Guillo, Pascal; Fasulo, Meg E; Lipschutz, Michael I; Tilley, T Don


    Tantalum polyhedral oligosilsesquioxane (POSS) complexes have been synthesised and characterized. X-ray structures of these complexes revealed that the coordination number of the tantalum center greatly affects the cube-like silsesquioxane framework.

  20. Homometallic rare-Earth metal phosphinidene clusters: synthesis and reactivity. (United States)

    Wang, Kai; Luo, Gen; Hong, Jianquan; Zhou, Xigeng; Weng, Linhong; Luo, Yi; Zhang, Lixin


    Two new trinuclear μ3 -bridged rare-earth metal phosphinidene complexes, [{L(Ln)(μ-Me)}3 (μ3 -Me)(μ3 -PPh)] (L=[PhC(NC6 H4 iPr2 -2,6)2 ](-) , Ln=Y (2 a), Lu (2 b)), were synthesized through methane elimination of the corresponding carbene precursors with phenylphosphine. Heating a toluene solution of 2 at 120 °C leads to an unprecedented ortho CH bond activation of the PhP ligand to form the bridged phosphinidene/phenyl complexes. Reactions of 2 with ketones, thione, or isothiocyanate show clear phospha-Wittig chemistry, giving the corresponding organic phosphinidenation products and oxide (sulfide) complexes. Reaction of 2 with CS2 leads to the formation of novel trinuclear rare-earth metal thione dianion clusters, for which a possible pathway was determined by DFT calculation. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Synthesis and tunable reactivity of N-heterocyclic germylene. (United States)

    Xiong, Yun; Yao, Shenglai; Driess, Matthias


    Modifying the β-diketimine ligand LH 1 (LH=[ArN=C(Me)-CH=C(Me)-NHAr], Ar=2,6-iPr(2)C(6)H(3)) through replacement of the proton in 3-position by a benzyl group (Bz) leads to the new (Bz)LH ligand 2, which could be isolated in 77% yield. According to (1) H NMR spectroscopy, 2 is a mixture of the bis(imino) form [(ArN=C(Me)](2)CH(Bz) 2a and its tautomer [ArN=C(Me)-C(Bz)=C(Me)NHAr] 2b. Nevertheless, lithiation of the mixture of 2a and 2b affords solely the N-lithiated β-diketiminate [ArN=C(Me)-C(Bz)=C(Me)-NLiAr], (Bz)LLi 3. The latter reacts readily with GeCl(2)· dioxane to form the chlorogermylene (Bz)LGeCl 4, which serves as a precursor for a new zwitterionic germylene by dehydrochlorination with LiN(SiMe(3))(2). This reaction leads to the zwitterionic germylene (Bz)L'Ge: 5 ((Bz)L'=ArNC(=CH(2))C(Bz)=C(Me)NAr) which could be isolated in 83% yield. The benzyl group has a distinct influence on the reactivity of zwitterionic 5 in comparison to its benzyl-free analogue, as shown by the reaction of 5 with phenylacetylene, which yields solely the 1,4-addition product 6, that is, the alkynyl germylene (Bz)LGeCCPh. Compounds 2-6 have been fully characterized by multinuclear NMR spectroscopy, mass spectrometry, elemental analyses, and single-crystal X-ray diffraction analyses.

  2. Low-reactive circulating fluidized bed combustion (CFBC) fly ashes as source material for geopolymer synthesis. (United States)

    Xu, Hui; Li, Qin; Shen, Lifeng; Zhang, Mengqun; Zhai, Jianping


    In this contribution, low-reactive circulating fluidized bed combustion (CFBC) fly ashes (CFAs) have firstly been utilized as a source material for geopolymer synthesis. An alkali fusion process was employed to promote the dissolution of Si and Al species from the CFAs, and thus to enhance the reactivity of the ashes. A high-reactive metakaolin (MK) was also used to consume the excess alkali needed for the fusion. Reactivities of the CFAs and MK were examined by a series of dissolution tests in sodium hydroxide solutions. Geopolymer samples were prepared by alkali activation of the source materials using a sodium silicate solution as the activator. The synthesized products were characterized by mechanical testing, scanning electron microscopy (SEM), X-ray diffractography (XRD), as well as Fourier transform infrared spectroscopy (FTIR). The results of this study indicate that, via enhancing the reactivity by alkali fusion and balancing the Na/Al ratio by additional aluminosilicate source, low-reactive CFAs could also be recycled as an alternative source material for geopolymer production.

  3. Synthesis and Crystal Structure of a New Salen Complex

    Institute of Scientific and Technical Information of China (English)

    LI Li-Jun; LI Ying; SUN Wen-Hua


    @@ Salen Schiff base complexes are some of the most important stereochemical models in transition metal coordina tion chemistry, with their ease of preparation and structural variation. [1] Salen complexes are extensively used as organic reaction catalysts, it was reported to be used in asymmetric cyclopropanation, epoxidation, aziridination, hydrolysis, alkylation, Diels-Alder reaction, reduction, oxidation etc. Here we report the synthesis and structure of a new salen nickel complex 4.

  4. Synthesis, characterization, and reactivity of sulfided hexanuclear molybdenum cluster compounds

    Energy Technology Data Exchange (ETDEWEB)

    Spink, D.


    Hexanuclear molybdenum clusters with mixed chloride and sulfide bridging ligands were prepared by reacting {alpha}-MoCl{sub 2} with sodium hydrosulfide in the presence of sodium butoxide. The resulting species, Mo{sub 6}Cl{sub (8-x)}S{sub x}{center dot}npy(x {congruent} 3.6, n {congruent} 4, py = pyridine), was pyrophoric and insoluble. The mixed sulfide chloride cluster species Mo{sub 6}S{sub 4}Cl{sub 4}{center dot}6OPEt{sub 3} and Mo{sub 6}S{sub {approximately}5}Cl{sub {approximately}3}{center dot}6PEt{sub 3} and Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3} were isolated and characterized. Phosphorus-31 nuclear magnetic resonance, electron paramagnetic resonance, and UV/visible spectra were obtained for each fraction. The completely sulfided cluster, Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3}, was prepared similarly and used in various experiments as a possible precursor to Chevrel phase materials of the type Mo{sub 6}S{sub 8}or M{sub n}Mo{sub 6}S{sub 8}. With the goal of removing all of the triethylphosphine ligands, Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3} was reacted with the transition metal carbonyls molybdenum hexacarbonyl and dicobalt octacarbonyl. Reaction on the molecular sulfide cluster with copper(I) chloride in toluene gave a completely insoluble product. The reaction of Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3} with propylene sulfide gave a product whose infrared spectra showed only very weak peaks associated with coordinated triethylphosphine. The elemental analysis of this product fit the formula Mo{sub 6}S{sub 8}{center dot}5SPEt{sub 3}. Reactivity of the outer ligands of the Mo{sub 6}S{sub 8}{center dot}npy and Mo{sub 6}S{sub 8}{center dot}(6{minus}x)PrNH{sub x} clusters were investigated. Crystalline Mo{sub 6}S{sub 8}{center dot}6THT was recovered from the reaction of the n-propylamine derivative with THT. A crystal structure determination was done. 87 refs., 12 fig., 15 tabs.

  5. CuI complexes with a noninnocent PNP Ligand: selective dearomatization and electrophilic addition reactivity

    NARCIS (Netherlands)

    van der Vlugt, J.I.; Pidko, E.A.; Vogt, D.; Lutz, M.; Spek, A.L.


    The neutral, T-shaped complex CuI(PN−PtBu) (2), featuring a dearomatized 2,6-bis(diphosphino)pyridine (PNP)-pincer ligand, is shown to interact rapidly with electrophiles. This has enabled the synthesis of acetato complex 3. Furthermore, C−C bond formation onto the deprotonated methylene-bridgehead

  6. Cu-I complexes with a noninnocent PNP ligand: Selective dearomatization and electrophilic addition reactivity

    NARCIS (Netherlands)

    van der Vlugt, J.I.; Pidko, E.A.; Vogt, D.; Lutz, M.; Spek, A.L.


    The neutral, T-shaped complex Cu-I((PN-PtBu)) (2), featuring a dearomatized 2,6-bis(diphosphino)pyridine (PNP)-pincer ligand, is shown to interact rapidly with electrophiles. This has enabled the synthesis of acetato complex 3. Furthermore, C-C bond formation onto the deprotonated methylene-bridgehe

  7. Colloidal stability and chemical reactivity of complex colloids containing Fe³⁺. (United States)

    van Leeuwen, Y M; Velikov, K P; Kegel, W K


    The reactivity of iron contained within insoluble colloidal metal-pyrophosphate salts was determined and compared to the reactivity of a soluble iron salt (FeCl3). As a model system for the reactivity of iron in food products, the formation of an iron-polyphenol complex was followed with spectrophotometry. Three types of systems were prepared and their colloidal stability and reactivity studied: Fe(3+) pyrophosphate, protein-coated Fe(3+) pyrophosphate and mixed-metal pyrophosphates containing Fe(3+) and a second cation M. The additional cation used was either monovalent (sodium) or divalent (M(2+)). It was found that: (i) incorporating iron in a colloidal salt reduced its reactivity compared to free Fe(3+) ions; (ii) coating the particles with a layer of hydrophobic protein (zein) increased stability and further decreased the reactivity. Finally, the most surprising result was that (iii) a mixed system containing more Fe(3+) than M actually increased the reactivity of the contained iron, while the reverse, a system containing excess M, inhibited the reactivity completely.

  8. Combustion synthesis of reactive nickel-aluminum particles as an innovative approach for thermal joining applications (United States)

    Schreiber, S.; Theodossiadis, G. D.; Zaeh, M. F.


    Reactive systems, which are widely used in combustion synthesis, represent a promising solution for challenging joining tasks. They are able to undergo a self-sustaining, highly exothermic reaction when exposed to an external energy source. Reactive foils are the only systems that are currently commercially available. However, their industrial use is limited due to the brittle nature of the material and the restriction to planar geometries. Reactive particles represent a more flexible format, but are currently not commercially available. Therefore, a two-step electroless plating process has been developed to synthesize nickel-aluminum core-shell structures. These structures function as microreactors, which provide the energy for the thermal joining process. Ignition tests with electromagnetic waves were performed in order to investigate the overall reactivity. Energy input and particle size significantly influence the activation and the reaction behavior of the core-shell structures. Furthermore, a general approach to use reactive particles as a heat source in joining applications is proposed.

  9. Statistical synthesis of multiantenna ultrawideband radiometric complexes (United States)

    Volosyuk, V. K.; Kravchenko, V. F.; Pavlikov, V. V.; Pustovoit, V. I.


    An optimum signal processing algorithm of radiometric imaging has been synthesized for the first time using multiantenna ultrawideband (UWB) radiometric complexes (RMCs). Radiometric images (RMI) are interpreted physically as intensity depending on the angular coordinates or the spectral radio brightness averaged in the operation frequency band. In accordance with the synthesized algorithm, a structural scheme of ultrawideband radiometric complexes has been developed. An analytical expression for the ambiguity function of radiometric complexes has been obtained. The ambiguity function is modeled in the case of processing narrowband and ultrawideband radiometric signals. As follows from the analysis of the results, new elements of the theory of optimum processing of UWB radiometric signals with the involvement of multielement antenna systems are an important tool in creating highly accurate, biologically and ecologically safe complexes for studying various media and objects.

  10. Redox-inactive metal ions modulate the reactivity and oxygen release of mononuclear non-haem iron(III)-peroxo complexes. (United States)

    Bang, Suhee; Lee, Yong-Min; Hong, Seungwoo; Cho, Kyung-Bin; Nishida, Yusuke; Seo, Mi Sook; Sarangi, Ritimukta; Fukuzumi, Shunichi; Nam, Wonwoo


    Redox-inactive metal ions that function as Lewis acids play pivotal roles in modulating the reactivity of oxygen-containing metal complexes and metalloenzymes, such as the oxygen-evolving complex in photosystem II and its small-molecule mimics. Here we report the synthesis and characterization of non-haem iron(III)-peroxo complexes that bind redox-inactive metal ions, (TMC)Fe(III)-(μ,η(2):η(2)-O2)-M(n+) (M(n+) = Sr(2+), Ca(2+), Zn(2+), Lu(3+), Y(3+) and Sc(3+); TMC, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). We demonstrate that the Ca(2+) and Sr(2+) complexes showed similar electrochemical properties and reactivities in one-electron oxidation or reduction reactions. However, the properties and reactivities of complexes formed with stronger Lewis acidities were found to be markedly different. Complexes that contain Ca(2+) or Sr(2+) ions were oxidized by an electron acceptor to release O2, whereas the release of O2 did not occur for complexes that bind stronger Lewis acids. We discuss these results in the light of the functional role of the Ca(2+) ion in the oxidation of water to dioxygen by the oxygen-evolving complex.

  11. Microwave assisted synthesis of fluorene-based copolymers with different conjugate degreed quinoxaline segments from reactive polymer

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jixin; Song, Xiaohui; Feng, Ying [School of Petrochemical Engineering, Shenyang University of Technology, 30 Guanghua Street, Liaoyang 111003 (China); Wang, Zhiming, E-mail: [School of Petrochemical Engineering, Shenyang University of Technology, 30 Guanghua Street, Liaoyang 111003 (China); State Key Laboratory of Supramolecular Structure and Materials, Jilin University, 2699 Qianjin Avenue, Changchun 130012 (China); Zhang, Xiaojuan [School of Petrochemical Engineering, Shenyang University of Technology, 30 Guanghua Street, Liaoyang 111003 (China); Shen, Fangzhong; Lu, Ping [State Key Laboratory of Supramolecular Structure and Materials, Jilin University, 2699 Qianjin Avenue, Changchun 130012 (China)


    In this work, we prepared three fluorene-based copolymers with different conjugate degreed quinoxaline segments from one reactive polymer by microwave assisted method. The obtained quinoxaline-based copolymers exhibited different bright color emissions, high photoluminescence quantum, low electron affinity and electron injection barrier. This approach not only simplified the steps of similar-structure polymers, but also avoided the monomer solubility problem. - Highlights: • Quinoxaline-based copolymers were prepared in microwave-assisted synthesis. • Polymer-synthesis containing different acceptors was simplified from reactive polymer. • Multi-functions were tuned by controlling reactive monomer structures.

  12. Green synthesis of multi metal- citrate complexes and their characterization (United States)

    Raju, Usha; Warkar, Sudhir G.; Kumar, Anil


    Four new multi metal-citrate complexes have been synthesized through green synthetic pathways. Their synthesis by hydrothermal route in the present research is decorated with features such as, a simple one pot synthesis, cost effectiveness, easy to scale up for commercial production, efficient synthesis conditions like mild temperature and shorter duration which further rules out the possibility of forming byproducts which may cause damage to the environment and being environmental benign as it eliminates the use and recovery of harmful organic solvents such as N, N- dimethyl formamide and N, N- diethyl formamide, used by the researchers in the past during the synthesis of similar metal- organic framework complexes. All four complexes are well defined crystalline materials with polynuclear multi metal-citrate framework having cubic crystal structure as indicated by their Powder X-ray Diffraction patterns. These complexes have been characterized by Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Thermogravimetric analysis and Powder XRD techniques.

  13. Dynamics of reactive oxygen species generation in the presence of copper(II)-histidine complex and cysteine. (United States)

    Ząbek-Adamska, Anna; Drożdż, Ryszard; Naskalski, Jerzy W


    Histidine-copper(II) complex (Cu-His2) is a form of bound copper necessary for cellular copper uptake. Due to the high affinity of histidine to copper(II) ions, the binding of copper(II) by histidine is considered a substantial part of plasma antioxidative defense. Also cysteine plays a role in the antioxidative system. However, we show here that in the presence of oxygen the histidine-copper(II) complex plus cysteine produces reactive oxygen species (ROS). Cysteine concentration was assayed using a thiol specific silver-mercury electrode. Hydrogen peroxide was assayed amperometrically using platinum electrode. ROS formation was followed by chemiluminescence of luminol-fluoresceine-enhanced system. Addition of cysteine to Cu-His2 solution at pH 7.4 in the presence of atmospheric oxygen initiates the synthesis of H2O2 and generation of ROS, which manifests as a burst of chemiluminescence. The reaction has two stages; in the first stage, cysteine is utilized for the synthesis of an unstable intermediary product which becomes a substrate for ROS formation. Anaerobic conditions inhibit ROS formation. Increased cysteine concentration enhances the lag phase of the oxidative burst without influencing the amount of ROS. The synthesis of ROS (measured by chemiluminescence) is proportional to the concentration of Cu-His2 employed. ROS production can be repetitively initiated by further additions of cysteine to the reaction medium. The study suggests that Cu-His2 catalyzes cysteine-dependent reduction of oxygen to superoxide employing an intermediary cysteine-copper(I) complex and enabling Fenton reaction with copper and hydrogen peroxide produced as a secondary product. In effect, Cu-His2 with cysteine may be a source of ROS in biological media.


    Directory of Open Access Journals (Sweden)

    Claudia Sasso


    Full Text Available Polypyrrole (PPy was chemically synthesised at two pH levels (pH = 2 and unadjusted pH, i.e. 6.6 using pre-formed carboxymethylcellulose-iron (CMC-Fe complexes. The CMC-Fe complexes were prepared at a fixed CMC concentration, i.e. 5.5x10-5 mol/L, and with an increasing FeCl3 amount (from 4x10-3 to 5x10-2 mol/L. The quantity of iron bound to CMC was determined by the inductively coupled plasma (ICP-MS method. In order to understand the interactions between CMC and iron, speciation of the systems was simulated by Phreeqc software. SEM analysis showed that, in some conditions (particularly at pH = 2, Py polymerised within the CMC-Fe complexes, forming particles with size ranging between 300 and 600 nm. In order to evaluate polymer electric conductivity, films were prepared by direct casting of the PPy-CMC-Fe dispersions with and without addition of film-forming CMC, and bulky PPy-CMC-Fe pellets were obtained by compression. Despite the different arrangement PPy-CMC-Fe particles in dry films, the amount of iron bound to CMC during the formation of CMC-Fe complexes was found to be the dominant parameter affecting polymer conductivity.

  15. Complex Nanostructures: Synthesis and Energetic Applications


    Dunwei Wang; Stafford Sheehan; Sa Zhou; Yongjing Lin; Xiaohua Liu


    Connected through single crystalline junctions, low dimensional materials such as nanowires and nanorods form complex nanostructures. These new materials exhibit mechanical strengths and electrical conductivities superior to their constituents while maintaining comparable surface areas, an attribute ideal for energetic applications. More efficient solar cells, higher capacity batteries and better performing photoelectrochemical cells have been built using these materials. This article reviews...

  16. Electroactive Bisiminopyridine Ligands: Synthesis and Complexation Studies

    Directory of Open Access Journals (Sweden)

    Narcis Avarvari


    Full Text Available The condensation reaction of (4-(6,7-dimethyldithio-tetrathiafulvalene-aniline with 2,6-diformylpyridine afforded an electroactive Schiff base (N,N,N pincer (3. This pincer was reacted with Zn(II cation to yield the corresponding Zinc chloride complex (4. The crystal structure of the newly prepared electroactive zinc complex reveals that the tetrathiafulvalene (TTF is neutral and the zinc cation is pentacoordinated. The two chlorines are involved in a set of hydrogen bonds giving rise to a 2D supramolecular grid arrangement. The electronic absorption properties and the electrochemical behavior have been elucidated. These two compounds are promising for the construction of crystalline radical cation salts.




    Polypyrrole (PPy) was chemically synthesised at two pH levels (pH = 2 and unadjusted pH, i.e. 6.6) using pre-formed carboxymethylcellulose-iron (CMC-Fe) complexes. The CMC-Fe complexes were prepared at a fixed CMC concentration, i.e. 5.5x10-5 mol/L, and with an increasing FeCl3 amount (from 4x10-3 to 5x10-2 mol/L). The quantity of iron bound to CMC was determined by the inductively coupled plasma (ICP-MS) method. In order to understand the interactions between CMC and iron, speciation of the ...

  18. Three component synthesis of substituted {eta}{sup 5}-cyclopentadienyltricarbonylrhenium complexes: Scope, limitations, and mechanistic interpretations

    Energy Technology Data Exchange (ETDEWEB)

    Minutolo, F.; Katzenellenbogen, J.A. [Univ. of Illinois, Urbana, IL (United States). Dept. of Chemistry


    The authors have investigated the scope and mechanism of the three-component synthesis of substituted CpRe(CO){sub 3} complexes which involves the reaction of nucleophiles with diazocyclopentadiene (C{sub 5}H{sub 4}N{sub 2}) and a fac-Re(CO){sub 3}{sup +} species. They found that only moderately strong nucleophiles (halogen, carboxylates, boronic acids) are suitable for this transformation and that it shows a great sensitivity to the steric and electronic features of the nucleophile. A Hammett-type {rho}{sigma} analysis of the effect of para-substituents on the relative rate of this reaction with several benzoates showed that the reaction is accelerated by electron-donating substituents. A mechanistic analysis, based on structure/reactivity relationships and NMR experiments, indicated that the nucleophile initially reacts with the rhenium precursor. Then, in the rate-determining step, the resulting preassociated rhenium-nucleophile intermediate reacts with C{sub 5}H{sub 4}N{sub 2} via a concerted S{sub N}2-like transition state. The same general mechanistic pathway seems to be followed by two very different classes of nucleophiles, carboxylates and boronic acids, in the synthesis of acyloxy- and carbon-substituted CpRe(CO){sub 3} complexes, respectively. In particular, the lack of reactivity of boronic esters can be explained by the necessary preassociation step between the rhenium and a deprotonated hydroxy group of the nucleophile, which is possible only with free boronic acids.

  19. Complex Hollow Nanostructures: Synthesis and Energy-Related Applications. (United States)

    Yu, Le; Hu, Han; Wu, Hao Bin; Lou, Xiong Wen David


    Hollow nanostructures offer promising potential for advanced energy storage and conversion applications. In the past decade, considerable research efforts have been devoted to the design and synthesis of hollow nanostructures with high complexity by manipulating their geometric morphology, chemical composition, and building block and interior architecture to boost their electrochemical performance, fulfilling the increasing global demand for renewable and sustainable energy sources. In this Review, we present a comprehensive overview of the synthesis and energy-related applications of complex hollow nanostructures. After a brief classification, the design and synthesis of complex hollow nanostructures are described in detail, which include hierarchical hollow spheres, hierarchical tubular structures, hollow polyhedra, and multi-shelled hollow structures, as well as their hybrids with nanocarbon materials. Thereafter, we discuss their niche applications as electrode materials for lithium-ion batteries and hybrid supercapacitors, sulfur hosts for lithium-sulfur batteries, and electrocatalysts for oxygen- and hydrogen-involving energy conversion reactions. The potential superiorities of complex hollow nanostructures for these applications are particularly highlighted. Finally, we conclude this Review with urgent challenges and further research directions of complex hollow nanostructures for energy-related applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Unified Synthesis of 10-Oxygenated Lycopodium Alkaloids: Impact of C10-Stereochemistry on Reactivity. (United States)

    Saha, Mrinmoy; Li, Xin; Collett, Nathan D; Carter, Rich G


    The pronounced impact of the C10 stereochemistry on the successful construction of a polycyclic Lycopodium alkaloid scaffold has been explored. A wide range of reaction conditions and functionality were investigated to control a keto sulfone Michael addition to construct the C7-C12 linkage. An unexpected, overriding impact of the C10 stereochemistry in stereoselectivity and reaction rate in the Michael addition was observed. Furthermore, divergent reactivity of a conformationally accelerated, intramolecular Mannich cyclization based on the C10 stereochemistry was discovered. The successful execution of this synthetic route resulted in the total synthesis of all three known 10-oxygenated Lycopodium alkaloids: 10-hydroxylycopodine, paniculine, and deacetylpaniculine.

  1. Arginine deiminase modulates endothelial tip cells via excessive synthesis of reactive oxygen species. (United States)

    Zhuo, Wei; Song, Xiaomin; Zhou, Hao; Luo, Yongzhang


    ADI (arginine deiminase), an enzyme that hydrolyses arginine, has been reported as an anti-angiogenesis agent. However, its molecular mechanism is unclear. We have demonstrated for the first time that ADI modulates the angiogenic activity of endothelial tip cells. By arginine depletion, ADI disturbs actin filament in endothelial tip cells, causing disordered migratory direction and decreased migration ability. Furthermore, ADI induces excessive synthesis of ROS (reactive oxygen species), and activates caspase 8-, but not caspase 9-, dependent apoptosis in endothelial cells. These findings provide a novel mechanism by which ADI inhibits tumour angiogenesis through modulating endothelial tip cells.

  2. Biomimetic Synthesis of Complex Flavonoids Isolated from Daemonorops "Dragon's Blood". (United States)

    Schmid, Matthias; Trauner, Dirk


    The dragonbloodins are a pair of complex flavonoid trimers that have been isolated from the palm tree Daemonorops draco, one of the sources of the ancient resin known as "dragon's blood". We present a short synthesis that clarifies their relative configurations and sheds light on their origin in Nature. This synthesis features biomimetic cascade reactions that involve both ionic and radical intermediates. The biogenetic relationships between dracorhodin, the dracoflavans C, and the dragonbloodins A1 and A2 are discussed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Synthesis and luminescence of some rare earth metal complexes (United States)

    Bochkarev, Mikhail N.; Pushkarev, Anatoly P.


    In the present paper the synthesis, photoand electroluminescent properties of new rare earth metal complexes prepared and studied at the Razuvaev Institute of Organometallic Chemistry during the last decade are reviewed. The obtained compounds give luminescence in UV, visible and NIR regions. The substituted phenolates, naphtholates, mercaptobenzothiazolate, 8-oxyquinolinolate, polyfluorinated alcoholates and chalcogenophosphinates were used as ligands. The synthesis and structure of unusual three-nuclear sulfidenitride clusters of Nd and Dy are described. The new excitation mechanism of ytterbium phenolates and naphtholates, which includes the stage of reversible reduction of Yb to divalent state and oxidation of the ligands in the excitation process, is discussed.

  4. Oligocyclopentadienyl transition metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    de Azevedo, Cristina G.; Vollhardt, K. Peter C.


    Synthesis, characterization, and reactivity studies of oligocyclopentadienyl transition metal complexes, namely those of fulvalene, tercyclopentadienyl, quatercyclopentadienyl, and pentacyclopentadienyl(cyclopentadienyl) are the subject of this account. Thermal-, photo-, and redox chemistries of homo- and heteropolynuclear complexes are described.

  5. Reactive oxygen species-dependent RhoA activation mediates collagen synthesis in hyperoxic lung fibrosis. (United States)

    Kondrikov, Dmitry; Caldwell, Ruth B; Dong, Zheng; Su, Yunchao


    Lung fibrosis is an ultimate consequence of pulmonary oxygen toxicity in human and animal models. Excessive production and deposition of extracellular matrix proteins, e.g., collagen-I, is the most important feature of pulmonary fibrosis in hyperoxia-induced lung injury. In this study, we investigated the roles of RhoA and reactive oxygen species (ROS) in collagen-I synthesis in hyperoxic lung fibroblasts and in a mouse model of oxygen toxicity. Exposure of human lung fibroblasts to hyperoxia resulted in RhoA activation and an increase in collagen-I synthesis and cell proliferation. Inhibition of RhoA by C3 transferase CT-04, dominant-negative RhoA mutant T19N, or RhoA siRNA prevented hyperoxia-induced collagen-I synthesis. The constitutively active RhoA mutant Q63L mimicked the effect of hyperoxia on collagen-I expression. Moreover, the Rho kinase inhibitor Y27632 inhibited collagen-I synthesis in hyperoxic lung fibroblasts and fibrosis in mouse lungs after oxygen toxicity. Furthermore, the ROS scavenger tiron attenuated hyperoxia-induced increases in RhoA activation and collagen-I synthesis in lung fibroblasts and mouse lungs after oxygen toxicity. More importantly, we found that hyperoxia induced separation of guanine nucleotide dissociation inhibitor (GDI) from RhoA in lung fibroblasts and mouse lungs. Further, tiron prevented the separation of GDI from RhoA in hyperoxic lung fibroblasts and mouse lungs with oxygen toxicity. Together, these results indicate that ROS-induced separation of GDI from RhoA leads to RhoA activation with oxygen toxicity. ROS-dependent RhoA activation is responsible for the increase in collagen-I synthesis in hyperoxic lung fibroblasts and mouse lungs.

  6. Biogenic nanoparticulate UO 2: Synthesis, characterization, and factors affecting surface reactivity (United States)

    Singer, David M.; Farges, François; Brown, Gordon E., Jr.


    The surface reactivity of biogenic, nanoparticulate UO 2 with respect to sorption of aqueous Zn(II) and particle annealing is different from that of bulk uraninite because of the presence of surface-associated organic matter on the biogenic UO 2. Synthesis of biogenic UO 2 was accomplished by reduction of aqueous uranyl ions, UO22+ by Shewanella putrefaciens CN32, and the resulting nanoparticles were washed using one of two protocols: (1) to remove surface-associated organic matter and soluble uranyl species (NAUO2), or (2) to remove only soluble uranyl species (BIUO2). A suite of bulk and surface characterization techniques was used to examine bulk and biogenic, nanoparticulate UO 2 as a function of particle size and surface-associated organic matter. The N 2-BET surface areas of the two biogenic UO 2 samples following the washing procedures are 128.63 m 2 g -1 (NAUO2) and 92.56 m 2 g -1 (BIUO2), and the average particle sizes range from 5-10 nm based on TEM imaging. Electrophoretic mobility measurements indicate that the surface charge behavior of biogenic, nanoparticulate UO 2 (both NAUO2 and BIUO2) over the pH range 3-9 is the same as that of bulk. The U L III-edge EXAFS spectra for biogenic UO 2 (both NAUO2 and BIUO2) were best fit with half the number of second-shell uranium neighbors compared to bulk uraninite, and no oxygen neighbors were detected beyond the first shell around U(IV) in the biogenic UO 2. At pH 7, sorption of Zn(II) onto both bulk uraninite and biogenic, nanoparticulate UO 2 is independent of electrolyte concentration, suggesting that Zn(II) sorption complexes are dominantly inner-sphere. The maximum surface area-normalized Zn(II) sorption loadings for the three substrates were 3.00 ± 0.20 μmol m -2 UO 2 (bulk uraninite), 2.34 ± 0.12 μmol m -2 UO 2 (NAUO2), and 2.57 ± 0.10 μmol m -2 UO 2 (BIUO2). Fits of Zn K-edge EXAFS spectra for biogenic, nanoparticulate UO 2 indicate that Zn(II) sorption is dependent on the washing protocol. Zn

  7. Complex Nanostructures: Synthesis and Energetic Applications

    Directory of Open Access Journals (Sweden)

    Dunwei Wang


    Full Text Available Connected through single crystalline junctions, low dimensional materials such as nanowires and nanorods form complex nanostructures. These new materials exhibit mechanical strengths and electrical conductivities superior to their constituents while maintaining comparable surface areas, an attribute ideal for energetic applications. More efficient solar cells, higher capacity batteries and better performing photoelectrochemical cells have been built using these materials. This article reviews this exciting new class of materials and covers topics from controlled syntheses to applications in photovoltaics, chemical energy conversion and electrical charge storage. Mechanisms responsible for the improved performance are discussed. The prospect of their applications in a broader energy-related field is analyzed.

  8. Complexes with nitrogen-centered radical ligands: classification, spectroscopic features, reactivity, and catalytic applications. (United States)

    Olivos Suarez, Alma I; Lyaskovskyy, Volodymyr; Reek, Joost N H; van der Vlugt, Jarl Ivar; de Bruin, Bas


    The electronic structure, spectroscopic features, and (catalytic) reactivity of complexes with nitrogen-centered radical ligands are described. Complexes with aminyl ([M(˙NR2)]), nitrene/imidyl ([M(˙NR)]), and nitridyl radical ligands ([M(˙N)]) are detectable and sometimes even isolable species, and despite their radical nature frequently reveal selective reactivity patterns towards a variety of organic substrates. A classification system for complexes with nitrogen-centered radical ligands based on their electronic structure leads to their description as one-electron-reduced Fischer-type systems, one-electron-oxidized Schrock-type systems, or systems with a (nearly) covalent M-N π bond. Experimental data relevant for the assignment of the radical locus (i.e. metal or ligand) are discussed, and the application of complexes with nitrogen-centered radical ligands in the (catalytic) syntheses of nitrogen-containing organic molecules such as aziridines and amines is demonstrated with recent examples. This Review should contribute to a better understanding of the (catalytic) reactivity of nitrogen-centered radical ligands and the role they play in tuning the reactivity of coordination compounds. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Effect of ligand denticity on the nitric oxide reactivity of cobalt(ii) complexes. (United States)

    Deka, Hemanta; Ghosh, Somnath; Saha, Soumen; Gogoi, Kuldeep; Mondal, Biplab


    The activation of nitric oxide (NO) by transition metal complexes has attracted a wide range of research activity. To study the role of ligand denticity on the NO reactivity of Co(ii) complexes, three complexes (, and ) were prepared with ligands , and [ = N(1),N(2)-bis(2,4,6-trimethylbenzyl)ethane-1,2-diamine; = N(1)-(2,4,6-trimethylbenzyl)-N(2)-(2-((2,4,6-trimethylbenzyl)amino)ethyl)ethane-1,2-diamine] and = N(1)-(2,4,6-trimethylbenzyl)-N(2),N(2)-bis(2-((2,4,6-trimethylbenzyl)amino)ethyl)ethane-1,2-diamine], respectively. The complexes differ from each other in terms of denticity and flexibility of the ligand frameworks. In degassed methanol solution, they were exposed to NO gas and their reactivity was studied using various spectroscopic techniques. In the case of complex with a bidentate ligand, reductive nitrosylation of the metal ion with concomitant dinitrosation of the ligand framework was observed. Complex with a tridentate ligand did not undergo reductive nitrosylation; rather, the formation of [Co(III)(NO(-))] was observed. The nitrosyl complexes were isolated and structurally characterized. On the other hand, complex with a tetradentate tripodal ligand did not react with NO. This can be attributed to the geometry of the complex as well as due to the accessibility of the corresponding redox potential.

  10. A Neutrally Charged Trimethylmanganese(III) Complex: Synthesis, Characterization, and Disproportionation Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Stalzer, Madelyn M.; Telser, Joshua; Krzystek, Jurek; Motta, Alessandro; Delferro, Massimiliano; Marks, Tobin J.


    The synthesis and properties of an unusual, neutrally charged and volatile N,N,N',N'-tetramethylethylenediamine trimethyl manganese(III) complex, (TMEDA)MnMe3, are described, along with its facile disproportionation to the corresponding Mn(II) and Mn(IV) complexes. Characterization by single-crystal XRD, UV-vis spectroscopy, high-frequency and -field EPR (HFEPR), magnetic susceptibility, and density functional theory (DFT) computations indicate that the (TMEDA)MnMe3 electronic structure can be described as largely square pyramidal Mn(III) centered. The paucity of manganese(III) polyalkyls and the simplicity and reactivity of this compound implicate it as a potentially useful synthetic building block.

  11. Design, synthesis and study of coordination complexes for quantum computing


    Aguilà Avilés, David


    This thesis presents different strategies for the design of molecular complexes with the requirements to be used as two-qubit quantum gates. The approaches followed towards the preparation of potential qubit systems have been carried out focusing on the synthesis of ligands with β-diketone coordination units, which are very versatile for the design of metallocluster assemblies. One of the main advantages of using this kind of ligands is that they can be easily prepared through simple Claisen ...

  12. Synthesis and Crystal Structure of a New Manganese Complex

    Institute of Scientific and Technical Information of China (English)

    WANG Jian; LIU Ping; CHEN Yun


    @@ In order to study the relationship between the manganese ion and the biological coordination agent, the role ofmanganese ion in the active sites and the structure of the active sites in the manganese enzymes, small molecule complexes are often applied to modeling the structure and the properties of reaction in the active centers. In this pa per, we will report the synthesis and crystal structure of a new manganese(Ⅱ) complex, catena[ aqua-(p-methoxybenzoato- O, O′ ) - (p-methoxybenzoato- O )- (2,2′-bipyridine)-manganese (Ⅱ) ] (p-methoxybenzoic acid). The crystal structure was confirmeded by X-ray crystallography analysis.

  13. Protein synthesis is the primary target of reactive oxygen species in the photoinhibition of photosystem II. (United States)

    Nishiyama, Yoshitaka; Allakhverdiev, Suleyman I; Murata, Norio


    Photoinhibition of photosystem II (PSII) occurs when the rate of photodamage to PSII exceeds the rate of the repair of photodamaged PSII. Recent examination of photoinhibition by separate determinations of photodamage and repair has revealed that the rate of photodamage to PSII is directly proportional to the intensity of incident light and that the repair of PSII is particularly sensitive to the inactivation by reactive oxygen species (ROS). The ROS-induced inactivation of repair is attributable to the suppression of the synthesis de novo of proteins, such as the D1 protein, that are required for the repair of PSII at the level of translational elongation. Furthermore, molecular analysis has revealed that the ROS-induced suppression of protein synthesis is associated with the specific inactivation of elongation factor G via the formation of an intramolecular disulfide bond. Impairment of various mechanisms that protect PSII against photoinhibition, including photorespiration, thermal dissipation of excitation energy, and the cyclic transport of electrons, decreases the rate of repair of PSII via the suppression of protein synthesis. In this review, we present a newly established model of the mechanism and the physiological significance of repair in the regulation of the photoinhibition of PSII.

  14. Mono(imidazolin-2-iminato) actinide complexes: synthesis and application in the catalytic dimerization of aldehydes. (United States)

    Karmel, Isabell S R; Fridman, Natalia; Tamm, Matthias; Eisen, Moris S


    The synthesis of the mono(imidazolin-2-iminato) actinide(IV) complexes [(Im(R)N)An(N{SiMe3)2}3] (3-8) was accomplished by the protonolysis reaction between the respective imidazolin-2-imine (Im(R)NH, R = tBu, Mes, Dipp) and the actinide metallacycles [{(Me3Si)N}2An{κ(2)C,N-CH2SiMe2N(SiMe3)}] (1, An = U; 2, M = Th). The thorium and uranium complexes were obtained in high yields, and their structures were established by single-crystal X-ray diffraction analysis. The mono(imidazolin-2-iminato) actinide complexes 3-8 display short An-N bonds together with large An-N-C angles, indicating strong electron donation from the imidazolin-2-iminato moiety to the metal, corroborating a substantial π-character to the An-N bond. The reactivity of complexes 3-8 toward benzaldehyde was studied in the catalytic dimerization of aldehydes (Tishchenko reaction), displaying low to moderate catalytic activities for the uranium complexes 3-5 and moderate to high catalytic activities for the thorium analogues 6-8, among which 8 exhibited the highest catalytic activity. In addition, actinide coordination compounds showed unprecedented reactivity toward cyclic and branched aliphatic aldehydes in the catalytic Tishchenko reaction mediated by the thorium complex [(Im(Dipp)N)Th{N(SiMe3)2}3] (8), exhibiting high activity even at room temperature. Moreover, complex 8 was successfully applied in the crossed Tishchenko reaction between an aromatic or polyaromatic and an aliphatic cyclic and branched aldehyde, yielding selectively the asymmetrically substituted ester in high yields (80-100%).

  15. Gold complexes with benzimidazole derivatives: synthesis, characterization and biological studies. (United States)

    Mota, Vinicius Zamprogno; de Carvalho, Gustavo Senra Gonçalves; da Silva, Adilson David; Costa, Luiz Antônio Sodré; de Almeida Machado, Patrícia; Coimbra, Elaine Soares; Ferreira, Carmen Veríssima; Shishido, Silvia Mika; Cuin, Alexandre


    Synthesis, characterization, DFT studies and biological assays of new gold(I) and gold(III) complexes of benzimidazole are reported. Molecular and structural characterizations of the compounds were based on elemental (C, H and N) and thermal (TG-DTA) analyses, and FT-IR and UV-Visible spectroscopic measurements. The structures of complexes were proposed based DFT calculations. The benzimidazole compounds (Lig1 and Lig2) and the gold complexes were tested against three Leishmania species related to cutaneous manifestations of leishmaniasis. The free benzimidazole compounds showed no leishmanicidal activity. On the other hand, the gold(I and III) complexes have shown to possess significant activity against Leishmania in both stages of parasite, and the gold(III) complex with Lig2 exhibited expressive leishmanicidal activity with IC50 values below 5.7 μM. Also, the gold complexes showed high leishmania selectivity. The gold(I) complex with Lig1, for example, is almost 50 times more toxic for the parasite than for macrophages. Besides the leishmanicidal activity, all complexes exhibited toxic effect against SK-Mel 103 and Balb/c 3T3, cancer cells.

  16. Radiochemical synthesis and preliminary in vivo evaluation of new radioactive platinum complexes with carnosine. (United States)

    Maurin, Michał; Garnuszek, Piotr


    Application of cross-linking agents such as SATA and 2-iminothiolane (2-IT) for radiochemical synthesis of new radioactive Pt(II) and Pt(IV) complexes with carnosine was investigated. The mixed-ligand Pt(II)([(125)I]Hist)(Carnosine) complex has been synthesized in a multi-step reaction. First, carnosine was modified by the attachment of SATA. After chromatographic purification, the conjugate was unprotected to form a reactive sulfhydryl functional group, and then the modified carnosine was substituted to PtCl(2)[(125)I]Hist complex. The Pt(II)(IT-[(125)I]Carnosine) and Pt(IV)(IT-[(131)I]Carnosine) complexes were synthesized in a three-step reaction. First, carnosine was labeled with iodine radionuclide ((125)I or (131)I), followed by conjugation with 2-IT. The modified IT-[*I]Carnosine was complexed with tetrachloroplatinate or hexachloroplatinate. Comparative biodistribution studies were performed in normal Wistar rats and in Lewis rats with implanted (s.c.) rat pancreatic tumor cells (AR42J). The HPLC analysis showed a relatively fast formation of the new mixed-ligand Pt([(125)I]Hist)(Carnosine) complex (yield ca. 50% after 20h). Reaction of K(2)PtCl(4) with [(125)I]Carnosine modified by 2-IT proceeded rapidly and with a high yield (>95% after 2h). The synthesis of the Pt(IV)IT-[*I]Carnosine complex was the slower reaction in comparison to the analogous synthesis of the Pt(II) complex (yield ca. 70% after 12h), thus a purification step was necessary. The biodistribution study proved the in vivo stability of the newly synthesized complexes (a low accumulation in thyroid gland and in GIT) and showed that the conjugation of the modified carnosine changes significantly biodistribution scheme of the Pt complexes comparing to the reference Pt(II)[*I]Hist and Pt(IV)([*I]Hist)(2) complexes. The mixed-ligand complex was rapidly excreted in urine and revealed the highest accumulation in kidneys (>5%ID/g). A very high concentration in blood and in liver was observed for the

  17. Synthetic strategies for efficient conjugation of organometallic complexes with pendant protein reactive markers

    KAUST Repository

    Jantke, Dominik


    Site-directed conjugation of metal centers to proteins is fundamental for biological and bioinorganic applications of transition metals. However, methods for the site-selective introduction of metal centers remain scarce. Herein, we present broadly applicable synthetic strategies for the conjugation of bioactive molecules with a range of organometallic complexes. Following three different synthetic strategies, we were able to synthesize a small library of metal conjugated protein markers featuring different types of protein reactive sites (epoxides, phenylphosphonates, fluorosulfonates and fluorophosphonate groups) as well as different late transition metals (iron, ruthenium, rhodium, palladium and platinum). The products were isolated in moderate to excellent yields and high purity. Furthermore, X-ray diffraction of the metalated protein markers corroborates structural integrity of the metal complex and the protein reactive site. © 2013 Elsevier B.V. All rights reserved.

  18. A Balancing Act: Stability versus Reactivity of Mn(O) Complexes. (United States)

    Neu, Heather M; Baglia, Regina A; Goldberg, David P


    A large class of heme and non-heme metalloenzymes utilize O2 or its derivatives (e.g., H2O2) to generate high-valent metal-oxo intermediates for performing challenging and selective oxidations. Due to their reactive nature, these intermediates are often short-lived and very difficult to characterize. Synthetic chemists have sought to prepare analogous metal-oxo complexes with ligands that impart enough stability to allow for their characterization and an examination of their inherent reactivity. The challenge in designing these molecules is to achieve a balance between their stability, which should allow for their in situ characterization or isolation, and their reactivity, in which they can still participate in interesting chemical transformations. This Account focuses on our recent efforts to generate and stabilize high-valent manganese-oxo porphyrinoid complexes and tune their reactivity in the oxidation of organic substrates. Dioxygen can be used to generate a high-valent Mn(V)(O) corrolazine (Mn(V)(O)(TBP8Cz)) by irradiation of Mn(III)(TBP8Cz) with visible light in the presence of a C-H substrate. Quantitative formation of the Mn(V)(O) complex occurs with concomitant selective hydroxylation of the benzylic substrate hexamethylbenzene. Addition of a strong H(+) donor converted this light/O2/substrate reaction from a stoichiometric to a catalytic process with modest turnovers. The addition of H(+) likely activates a transient Mn(V)(O) complex to achieve turnover, whereas in the absence of H(+), the Mn(V)(O) complex is an unreactive "dead-end" complex. Addition of anionic donors to the Mn(V)(O) complex also leads to enhanced reactivity, with a large increase in the rate of two-electron oxygen atom transfer (OAT) to thioether substrates. Spectroscopic characterization (Mn K-edge X-ray absorption and resonance Raman spectroscopies) revealed that the anionic donors (X(-)) bind to the Mn(V) ion to form six-coordinate [Mn(V)(O)(X)](-) complexes. An unusual "V

  19. Transient Formation and Reactivity of a High-Valent Nickel(IV) Oxido Complex

    NARCIS (Netherlands)

    Padamati, Sandeep K.; Angelone, Davide; Draksharapu, Apparao; Primi, Gloria; Martin, David J.; Tromp, Moniek; Swart, Marcel; Browne, Wesley R.


    A reactive high-valent dinuclear nickel(IV) oxido bridged complex is reported that can be formed at room temperature by reaction of [(L)2Ni(II)2(μ-X)3]X (X = Cl or Br) with NaOCl in methanol or acetonitrile (where L = 1,4,7-trimethyl-1,4,7-triazacyclononane). The unusual Ni(IV) oxido species is

  20. Synthesis and Spectral Evaluation of Some Unsymmetrical Mesoporphyrinic Complexes

    Directory of Open Access Journals (Sweden)

    Rica Boscencu


    Full Text Available Synthesis and spectral evaluation of new zinc and copper unsymmetrical mesoporphyrinic complexes are reported. Zn(II-5-(4-acetoxy-3-methoxyphenyl-10,15,20-tris-(4-carboxymethylphenylporphyrin, Zn(II-5-[(3,4-methylenedioxyphenyl]-10,15,20-tris-(4-carboxymethylphenylporphyrin, Cu(II-5-(4-acetoxy-3-methoxyphenyl-10,15,20-tris-(4-carboxymethylphenylporphyrin and Cu(II-5-[(3,4-methylenedioxyphenyl]-10,15,20-tris-(4-carboxymethylphenylporphyrin were synthesized using microwave-assisted synthesis. The complexes were characterized by elemental analysis, FT-IR, UV-Vis, EPR and NMR spectroscopy, which fully confirmed their structure. The spectral absorption properties of the porphyrinic complexes were studied in solvents with different polarities. Fluorescence emission and singlet oxygen formation quantum yields were evaluated for the compounds under study, revealing high yields for the zinc derivatives. The copper complexes are not emissive and only display residual capacity for singlet oxygen formation.

  1. Synthesis and spectral evaluation of some unsymmetrical mesoporphyrinic complexes. (United States)

    Boscencu, Rica; Oliveira, Anabela Sousa; Ferreira, Diana P; Ferreira, Luís Filipe Vieira


    Synthesis and spectral evaluation of new zinc and copper unsymmetrical mesoporphyrinic complexes are reported. Zn(II)-5-(4-acetoxy-3-methoxyphenyl)-10,15,20- tris-(4-carboxymethylphenyl)porphyrin, Zn(II)-5-[(3,4-methylenedioxy)phenyl]-10,15,20- tris-(4-carboxymethylphenyl)porphyrin, Cu(II)-5-(4-acetoxy-3-methoxyphenyl)-10,15,20- tris-(4-carboxymethylphenyl)porphyrin and Cu(II)-5-[(3,4-methylenedioxy)phenyl]-10,15,20- tris-(4-carboxymethylphenyl)porphyrin were synthesized using microwave-assisted synthesis. The complexes were characterized by elemental analysis, FT-IR, UV-Vis, EPR and NMR spectroscopy, which fully confirmed their structure. The spectral absorption properties of the porphyrinic complexes were studied in solvents with different polarities. Fluorescence emission and singlet oxygen formation quantum yields were evaluated for the compounds under study, revealing high yields for the zinc derivatives. The copper complexes are not emissive and only display residual capacity for singlet oxygen formation.

  2. Nuclear chemistry. Synthesis and detection of a seaborgium carbonyl complex. (United States)

    Even, J; Yakushev, A; Düllmann, Ch E; Haba, H; Asai, M; Sato, T K; Brand, H; Di Nitto, A; Eichler, R; Fan, F L; Hartmann, W; Huang, M; Jäger, E; Kaji, D; Kanaya, J; Kaneya, Y; Khuyagbaatar, J; Kindler, B; Kratz, J V; Krier, J; Kudou, Y; Kurz, N; Lommel, B; Miyashita, S; Morimoto, K; Morita, K; Murakami, M; Nagame, Y; Nitsche, H; Ooe, K; Qin, Z; Schädel, M; Steiner, J; Sumita, T; Takeyama, M; Tanaka, K; Toyoshima, A; Tsukada, K; Türler, A; Usoltsev, I; Wakabayashi, Y; Wang, Y; Wiehl, N; Yamaki, S


    Experimental investigations of transactinoide elements provide benchmark results for chemical theory and probe the predictive power of trends in the periodic table. So far, in gas-phase chemical reactions, simple inorganic compounds with the transactinoide in its highest oxidation state have been synthesized. Single-atom production rates, short half-lives, and harsh experimental conditions limited the number of experimentally accessible compounds. We applied a gas-phase carbonylation technique previously tested on short-lived molybdenum (Mo) and tungsten (W) isotopes to the preparation of a carbonyl complex of seaborgium, the 106th element. The volatile seaborgium complex showed the same volatility and reactivity with a silicon dioxide surface as those of the hexacarbonyl complexes of the lighter homologs Mo and W. Comparison of the product's adsorption enthalpy with theoretical predictions and data for the lighter congeners supported a Sg(CO)6 formulation.

  3. Synthesis, structure and reactivity of Ni site models of [NiFeSe] hydrogenases. (United States)

    Wombwell, Claire; Reisner, Erwin


    A series of structural models of the Ni centre in [NiFeSe] hydrogenases has been developed which exhibits key structural features of the Ni site in the H2 cycling enzyme. Specifically, two complexes with a hydrogenase-analogous four-coordinate 'NiS3Se' primary coordination sphere and complexes with a 'NiS2Se2' and a 'NiS4' core are reported. The reactivity of the complexes towards oxygen and protons shows some relevance to the chemistry of [NiFeSe] hydrogenases. Exposure of a 'NiS3Se' complex to atmospheric oxygen results in the oxidation of the selenolate group in the complex to a diselenide, which is released from the nickel site. Oxidation of the selenolate ligand on Ni occurs approximately four times faster than oxidation with the analogous sulfur complex. Reaction of the complexes with one equivalent of HBF4 results in protonation of the monodentate chalcogenolate and the release of this ligand from the metal centre as a thiol or selenol. Unrelated to their biomimetic nature, the complexes serve also as molecular precursors to modify electrodes with Ni-S-Se containing particles by electrochemical deposition. The activated electrodes evolve H2 in pH neutral water with an electrocatalytic onset potential of -0.6 V and a current density of 15 μA cm(-2) at -0.75 V vs. NHE.

  4. Synthesis and Characterization of Reactive Powder Concrete for its Application on Thermal Insulation Panels (United States)

    Chozas, V.; Larraza, Í.; Vera-Agullo, J.; Williams-Portal, N.; Mueller, U.; Da Silva, N.; Flansbjer, M.


    This paper describes the synthesis and characterization of a set of textile reinforced reactive powder concrete (RPC) mixes that have been prepared in the framework of the SESBE project which aims to develop facade panels for the building envelope. In order to reduce the environmental impact, high concentration of type I and II mineral additions were added to the mixtures (up to 40% of cement replacement). The mechanical properties of the materials were analysed showing high values of compression strength thus indicating no disadvantages in the compression mechanical performance (∼140 MPa) and modulus of elasticity. In order to enable the use of these materials in building applications, textile reinforcement was introduced by incorporating layers of carbon fibre grids into the RPC matrix. The flexural performance of these samples was analysed showing high strength values and suitability for their further utilization.

  5. Lewis Acid Zeolites for Biomass Conversion: Perspectives and Challenges on Reactivity, Synthesis, and Stability. (United States)

    Luo, Helen Y; Lewis, Jennifer D; Román-Leshkov, Yuriy


    Zeolites containing Sn, Ti, Zr, Hf, Nb, or Ta heteroatoms are versatile catalysts for the activation and conversion of oxygenated molecules owing to the unique Lewis acid character of their tetrahedral metal sites. Through fluoride-mediated synthesis, hydrophobic Lewis acid zeolites can behave as water-tolerant catalysts, which has resulted in a recent surge of experimental and computational studies in the field of biomass conversion. However, many open questions still surround these materials, especially relating to the nature of their active sites. This lack of fundamental understanding is exemplified by the many dissonant results that have been described in recent literature reports. In this review, we use a molecular-based approach to provide insight into the relationship between the structure of the metal center and its reactivity toward different substrates, with the ultimate goal of providing a robust framework to understand the properties that have the strongest influence on catalytic performance for the conversion of oxygenates.

  6. Synthesis of novel amorphous calcium carbonate by sono atomization for reactive mixing. (United States)

    Kojima, Yoshiyuki; Kanai, Makoto; Nishimiya, Nobuyuki


    Droplets of several micrometers in size can be formed in aqueous solution by atomization under ultrasonic irradiation at 2 MHz. This phenomenon, known as atomization, is capable of forming fine droplets for use as a reaction field. This synthetic method is called SARM (sono atomization for reactive mixing). This paper reports on the synthesis of a novel amorphous calcium carbonate formed by SARM. The amorphous calcium carbonate, obtained at a solution concentration of 0.8 mol/dm(3), had a specific surface area of 65 m(2)/g and a composition of CaCO(3)•0.5H(2)O as determined using thermogravimetric/differential thermal analysis (TG-DTA). Because the ACC had a lower hydrate composition than conventional amorphous calcium carbonate (ACC), the ACC synthesized in this paper was very stable at room temperature.

  7. Synthesis of ternary metal nitride nanoparticles using mesoporous carbon nitride as reactive template. (United States)

    Fischer, Anna; Müller, Jens Oliver; Antonietti, Markus; Thomas, Arne


    Mesoporous graphitic carbon nitride was used as both a nanoreactor and a reactant for the synthesis of ternary metal nitride nanoparticles. By infiltration of a mixture of two metal precursors into mesoporous carbon nitride, the pores act first as a nanoconfinement, generating amorphous mixed oxide nanoparticles. During heating and decomposition, the carbon nitride second acts as reactant or, more precisely, as a nitrogen source, which converts the preformed mixed oxide nanoparticles into the corresponding nitride (reactive templating). Using this approach, ternary metal nitride particles with diameters smaller 10 nm composed of aluminum gallium nitride (Al-Ga-N) and titanium vanadium nitride (Ti-V-N) were synthesized. Due to the confinement effect of the carbon nitride matrix, the composition of the resulting metal nitride can be easily adjusted by changing the concentration of the preceding precursor solution. Thus, ternary metal nitride nanoparticles with continuously adjustable metal composition can be produced.

  8. Polyporphyrin Complexes of Some Transition Metals. Synthesis and Catalytic Properties

    Directory of Open Access Journals (Sweden)

    A.V. Shakhvorostov


    Full Text Available The paper presents the results of synthesis of polyporphyrin structures and metal complex catalyzers at their basis. Porphyrin to be derived from the addition reaction of pyrrole and formaldehyde. Metal complex catalyzers to be derived at the reaction of complex formation of ions of Mn2+, Co2+, Ni2+ and Fe3+ with porphyrin. The structure, physical and chemical properties of derived materials to be examined with IR spectroscopy, differential thermal analysis, thermogravimetric analysis, scanning electron microscopy investigation. Catalytic activity of synthesized catalytic systems to be established at the reaction of decompounding of hydrogen peroxide and alkylaromatics oxidation by hydrogen peroxide. The processes have been conducted under soft conditions, and also at different organic solvents.

  9. Chemistry of Iron N -heterocyclic carbene complexes: Syntheses, structures, reactivities, and catalytic applications

    KAUST Repository

    Riener, Korbinian


    Iron is the most abundant transition metal in Earth\\'s crust. It is relatively inexpensive, not very toxic, and environmentally benign. Undoubtedly, due to the involvement in a multitude of biological processes, which heavily rely on the rich functionalities of iron-containing enzymes, iron is one of the most important elements in nature. Additionally, three-coordinate iron complexes have been reported during the past several years. In this review, the mentioned iron NHC complexes are categorized by their main structure and reactivity attributes. Thus, monocarbene and bis-monocarbene complexes are presented first. This class is subdivided into carbonyl, nitrosyl, and halide compounds followed by a brief section on other, more unconventional iron NHC motifs. Subsequently, donor-substituted complexes bearing bi-, tri-, tetra-, or even pentadentate ligands and further pincer as well as scorpionato motifs are described.

  10. Amide Synthesis from Alcohols and Amines Catalyzed by Ruthenium N-Heterocyclic Carbene Complexes

    DEFF Research Database (Denmark)

    Dam, Johan Hygum; Osztrovszky, Gyorgyi; Nordstrøm, Lars Ulrik Rubæk


    The direct synthesis of amides from alcohols and amines is described with the simultaneous liberation of dihydrogen. The reaction does not require any stoichiometric additives or hydrogen acceptors and is catalyzed by ruthenium N-heterocyclic carbene complexes. Three different catalyst systems...... chloride and base. A range of different primary alcohols and amines have been coupled in the presence of the three catalyst systems to afford the corresponding amides in moderate to excellent yields. The best results are obtained with sterically unhindered alcohols and amines. The three catalyst systems do...... not show any significant differences in reactivity, which indicates that the same catalytically active species is operating. The reaction is believed to proceed by initial dehydrogenation of the primary alcohol to the aldehyde that stays coordinated to ruthenium and is not released into the reaction...

  11. Modeling the surface tension of complex, reactive organic-inorganic mixtures (United States)

    Schwier, A. N.; Viglione, G. A.; Li, Z.; McNeill, V. Faye


    Atmospheric aerosols can contain thousands of organic compounds which impact aerosol surface tension, affecting aerosol properties such as heterogeneous reactivity, ice nucleation, and cloud droplet formation. We present new experimental data for the surface tension of complex, reactive organic-inorganic aqueous mixtures mimicking tropospheric aerosols. Each solution contained 2-6 organic compounds, including methylglyoxal, glyoxal, formaldehyde, acetaldehyde, oxalic acid, succinic acid, leucine, alanine, glycine, and serine, with and without ammonium sulfate. We test two semi-empirical surface tension models and find that most reactive, complex, aqueous organic mixtures which do not contain salt are well described by a weighted Szyszkowski-Langmuir (S-L) model which was first presented by Henning et al. (2005). Two approaches for modeling the effects of salt were tested: (1) the Tuckermann approach (an extension of the Henning model with an additional explicit salt term), and (2) a new implicit method proposed here which employs experimental surface tension data obtained for each organic species in the presence of salt used with the Henning model. We recommend the use of method (2) for surface tension modeling of aerosol systems because the Henning model (using data obtained from organic-inorganic systems) and Tuckermann approach provide similar modeling results and goodness-of-fit (χ2) values, yet the Henning model is a simpler and more physical approach to modeling the effects of salt, requiring less empirically determined parameters.

  12. Utilizing the σ-complex stability for quantifying reactivity in nucleophilic substitution of aromatic fluorides

    Directory of Open Access Journals (Sweden)

    Magnus Liljenberg


    Full Text Available A computational approach using density functional theory to compute the energies of the possible σ-complex reaction intermediates, the “σ-complex approach”, has been shown to be very useful in predicting regioselectivity, in electrophilic as well as nucleophilic aromatic substitution. In this article we give a short overview of the background for these investigations and the general requirements for predictive reactivity models for the pharmaceutical industry. We also present new results regarding the reaction rates and regioselectivities in nucleophilic substitution of fluorinated aromatics. They were rationalized by investigating linear correlations between experimental rate constants (k from the literature with a theoretical quantity, which we call the sigma stability (SS. The SS is the energy change associated with formation of the intermediate σ-complex by attachment of the nucleophile to the aromatic ring. The correlations, which include both neutral (NH3 and anionic (MeO− nucleophiles are quite satisfactory (r = 0.93 to r = 0.99, and SS is thus useful for quantifying both global (substrate and local (positional reactivity in SNAr reactions of fluorinated aromatic substrates. A mechanistic analysis shows that the geometric structure of the σ-complex resembles the rate-limiting transition state and that this provides a rationale for the observed correlations between the SS and the reaction rate.

  13. Utilizing the σ-complex stability for quantifying reactivity in nucleophilic substitution of aromatic fluorides. (United States)

    Liljenberg, Magnus; Brinck, Tore; Rein, Tobias; Svensson, Mats


    A computational approach using density functional theory to compute the energies of the possible σ-complex reaction intermediates, the "σ-complex approach", has been shown to be very useful in predicting regioselectivity, in electrophilic as well as nucleophilic aromatic substitution. In this article we give a short overview of the background for these investigations and the general requirements for predictive reactivity models for the pharmaceutical industry. We also present new results regarding the reaction rates and regioselectivities in nucleophilic substitution of fluorinated aromatics. They were rationalized by investigating linear correlations between experimental rate constants (k) from the literature with a theoretical quantity, which we call the sigma stability (SS). The SS is the energy change associated with formation of the intermediate σ-complex by attachment of the nucleophile to the aromatic ring. The correlations, which include both neutral (NH3) and anionic (MeO(-)) nucleophiles are quite satisfactory (r = 0.93 to r = 0.99), and SS is thus useful for quantifying both global (substrate) and local (positional) reactivity in SNAr reactions of fluorinated aromatic substrates. A mechanistic analysis shows that the geometric structure of the σ-complex resembles the rate-limiting transition state and that this provides a rationale for the observed correlations between the SS and the reaction rate.

  14. Odd [n]Cumulenes (n = 3, 5, 7, 9): Synthesis, Characterization, and Reactivity. (United States)

    Wendinger, Dominik; Tykwinski, Rik R


    In comparison to the omnipresent two- and three-dimensional allotropes of carbon, namely, graphite and diamond (as well as recent entries graphene, carbon nanotubes, and fullerenes), a detailed understanding of the one-dimensional carbon allotrope carbyne is not well established, and even the existence of carbyne has been a matter of controversy over the past decades. Composed of sp-hybridized carbon, carbyne could potentially exist in two forms, either as a polyyne (alternating single and triple bonds, expected to show a semiconducting behavior) or as a cumulene (all carbon atoms are connected via double bonds, predicted to show metallic behavior). Although a number of publications are available on the hypothetical structure and properties of carbyne, specific knowledge about its physical and spectroscopic characteristics is still unclear. In order to predict the properties of carbyne, the synthesis and study of model compounds, namely, polyynes and cumulenes, has been a promising avenue. The synthesis of polyynes has been extensively explored in the last decades, culminating with the isolation of a polyyne with 22 acetylene units, which allows extrapolation to the properties of carbyne. Extended cumulenes, on the other hand, have remained much less well-known, and specific studies of properties versus molecular length are quite limited. A limiting factor to the study of [n]cumulenes has been their dramatically increased reactivity, especially in comparison to polyynes of comparable length. For example, most known [7]cumulenes can only be handled in solution, while the polyynes of equivalent length (i.e., a triyne with three acetylene units) are quite stable. [9]Cumulenes are the longest derivatives studied to date. In this Account, we describe our efforts to design and synthesize odd [n]cumulenes (i.e., n = 3, 5, 7, 9) that are sufficiently persistent under ambient conditions to allow in depth characterization of physical and spectral properties. This goal has

  15. Synthesis of l-cysteine derivatives containing stable sulfur isotopes and application of this synthesis to reactive sulfur metabolome. (United States)

    Ono, Katsuhiko; Jung, Minkyung; Zhang, Tianli; Tsutsuki, Hiroyasu; Sezaki, Hiroshi; Ihara, Hideshi; Wei, Fan-Yan; Tomizawa, Kazuhito; Akaike, Takaaki; Sawa, Tomohiro


    Cysteine persulfide is an L-cysteine derivative having one additional sulfur atom bound to a cysteinyl thiol group, and it serves as a reactive sulfur species that regulates redox homeostasis in cells. Here, we describe a rapid and efficient method of synthesis of L-cysteine derivatives containing isotopic sulfur atoms and application of this method to a reactive sulfur metabolome. We used bacterial cysteine syntheses to incorporate isotopic sulfur atoms into the sulfhydryl moiety of L-cysteine. We cloned three cysteine synthases-CysE, CysK, and CysM-from the Gram-negative bacterium Salmonella enterica serovar Typhimurium LT2, and we generated their recombinant enzymes. We synthesized (34)S-labeled L-cysteine from O-acetyl-L-serine and (34)S-labeled sodium sulfide as substrates for the CysK or CysM reactions. Isotopic labeling of L-cysteine at both sulfur ((34)S) and nitrogen ((15)N) atoms was also achieved by performing enzyme reactions with (15)N-labeled L-serine, acetyl-CoA, and (34)S-labeled sodium sulfide in the presence of CysE and CysK. The present enzyme systems can be applied to syntheses of a series of L-cysteine derivatives including L-cystine, L-cystine persulfide, S-sulfo-L-cysteine, L-cysteine sulfonate, and L-selenocystine. We also prepared (34)S-labeled N-acetyl-L-cysteine (NAC) by incubating (34)S-labeled L-cysteine with acetyl coenzyme A in test tubes. Tandem mass spectrometric identification of low-molecular-weight thiols after monobromobimane derivatization revealed the endogenous occurrence of NAC in the cultured mammalian cells such as HeLa cells and J774.1 cells. Furthermore, we successfully demonstrated, by using (34)S-labeled NAC, metabolic conversion of NAC to glutathione and its persulfide, via intermediate formation of L-cysteine, in the cells. The approach using isotopic sulfur labeling combined with mass spectrometry may thus contribute to greater understanding of reactive sulfur metabolome and redox biology. Copyright © 2017 Elsevier

  16. Polymer supported nickel complex: Synthesis, structure and catalytic application

    Indian Academy of Sciences (India)

    Alekha Kumar Sutar; Tungabidya Maharana; Yasobanta Das; Prasanta Rath


    In the present investigation, a new synthetic route for a novel recyclable free [3-MOBdMBn-Ni] and polystyrene-anchored [P-3-MOBdMBn-Ni] nickel complexes is presented. The free and polymer-anchored metal complexes were synthesized by the reaction of nickel (II) with one molar equivalent of unsupported N N′-bis (2-Hydroxy-3-methoxybenzaldehyde) 4-Methylbenzene-1,2-diamine (3-MOBdMBn) or polymersupported (P-3-MOBdMBn) Schiff-base ligand in methanol under nitrogen atmosphere. The advantages of these polymer-supported catalysts are the low cost of catalyst and recyclability up to six times, due to easy availability of materials and simple synthetic route. The higher efficiency of complexation of nickel on the polymer-anchored 3-MOBdMBn Schiff base than the unsupported analogue is another advantage of this catalyst system. The structural study reveals that nickel(II) complex of 3-MOBdMBn is square planar in geometry. The catalytic activity of nickel complex towards the oxidation of phenol was investigated in the presence of hydrogen peroxide. Experimental results indicate that the reactivity of P-3-MOBdMBn-Ni was dramatically affected by the polymer support compared to free 3-MOBdMBn-Ni. The rates of oxidation (R) for unsupported and supported catalysts are 1.37 × 10-6 mole dm-3 s-1 and 2.33 × 10-6 mole dm-3 s-1 respectively.

  17. Synthesis, stability and reactivity of the first mononuclear nonheme oxoiron(IV) species with monoamido ligation: a putative reactive species generated from iron-bleomycin. (United States)

    Hitomi, Yutaka; Arakawa, Kengo; Kodera, Masahito


    The preparation and characterisation of an oxoiron(IV) species with monoamido ligation are described. Reactivity studies revealed the important role of the amido ligand in enhancing the ability of oxoiron(IV) complexes to promote hydrogen atom transfer from external alkanes.

  18. Synthesis and self-assembly of complex hollow materials

    KAUST Repository

    Zeng, Hua Chun


    Hollow materials with interiors or voids and pores are a class of lightweight nanostructured matters that promise many future technological applications, and they have received significant research attention in recent years. On the basis of well-known physicochemical phenomena and principles, for example, several solution-based protocols have been developed for the general preparation of these complex materials under mild reaction conditions. This article is thus a short introductory review on the synthetic aspects of this field of development. The synthetic methodologies can be broadly divided into three major categories: (i) template-assisted synthesis, (ii) self-assembly with primary building blocks, and (iii) induced matter relocations. In most cases, both synthesis and self-assembly are involved in the above processes. Further combinations of these methodologies appear to be very important, as they will allow one to prepare functional materials at a higher level of complexity and precision. The synthetic strategies are introduced through some simple case studies with schematic illustrations. Salient features of the methods developed have been summarized, and some urgent issues of this field have also been indicated. © 2011 The Royal Society of Chemistry.

  19. From a cycloheptatrienylzirconium allyl complex to a cycloheptatrienylzirconium imidazolin-2-iminato "pogo stick" complex with imido-type reactivity. (United States)

    Glöckner, Andreas; Bannenberg, Thomas; Daniliuc, Constantin G; Jones, Peter G; Tamm, Matthias


    The reaction of the cycloheptatrienylzirconium half-sandwich complex [(η(7)-C(7)H(7))ZrCl(tmeda)] (1) (tmeda = N,N,N',N'-tetramethylethylenediamine) with Li(Im(Dipp)N), generated from bis(2,6-diisopropylphenyl)imidazolin-2-imine (Im(Dipp)NH) with methyllithium, yields the imidazolin-2-iminato complex [(η(7)-C(7)H(7))Zr(Im(Dipp)N)(tmeda)] (2). The corresponding tmeda-free complex [(η(7)-C(7)H(7))Zr(Im(Dipp)N)] (5) can be synthesized via the 1,3-bis(trimethylsilyl)allyl complex [(η(7)-C(7)H(7))Zr{η(3)-C(3)H(3)(TMS)(2)}(THF)] (3; TMS = SiMe(3)), which undergoes an acid-base reaction with Im(Dipp)NH to form 5 and 1,3-bis(trimethylsilyl)propene. 5 exhibits an unusual one-legged piano stool ("pogo stick") geometry with a particularly short Zr-N bond of 1.997(2) Å. Addition of 2,6-dimethylphenyl or tert-butyl isocyanide affords the complexes [(η(7)-C(7)H(7))Zr(Im(Dipp)N)(CNR)] (R = o-Xy, 6; R = t-Bu, 7), while the reaction with 2,6-dimethylphenyl isocyanate results in a [2 + 2] cycloaddition to form the ureato(1-) complex [(η(7)-C(7)H(7))Zr{Im(Dipp)N(C═O)N-o-Xy}] (8). 5 can also act as an initiator for the ring-opening polymerization of ε-caprolactone. These reactivity patterns together with density functional theory calculations reveal a marked similarity of the bonding in imidazolin-2-iminato and conventional imido transition-metal complexes.

  20. Combining bifunctional chelator with (3 + 2)-cycloaddition approaches: synthesis of dual-function technetium complexes. (United States)

    Braband, Henrik; Imstepf, Sebastian; Benz, Michael; Spingler, Bernhard; Alberto, Roger


    A new concept for the synthesis of dual-functionalized technetium (Tc) compounds is presented, on the basis of the reactivity of fac-{Tc(VII)O(3)}(+) complexes. The concept combines the "classical" bifunctional chelator (BFC) approach with the new ligand centered labeling strategy of fac-{TcO(3)}(+) complexes with alkenes ((3 + 2)-cycloaddition approach). To evidence this concept, fac-{(99)TcO(3)}(+) model complexes containing functionalized 1,4,7-triazacyclononane (tacn) derivatives N-benzyl-2-(1,4,7-triazonan-1-yl)acetamide (tacn-ba) and 2,2',2″-(1,4,7-triazonane-1,4,7-triyl)triacetic acid (nota·3H) were synthesized and characterized. Whereas [(99)TcO(3)(tacn-ba)](+) [2](+) can be synthesized following a established oxidation procedure starting from the Tc(V) complex [(99)TcO(glyc)(tacn-ba)](+) [1](+), a new synthetic pathway for the synthesis of [(99)TcO(3)(nota)](2-) [5](2-) had to be developed, starting from [(99)Tc(nota·3H)(CO)(3)](+) [4](+) and using sodium perborate tetrahydrate (NaBO(3)·4H(2)O) as oxidizing reagent. While [(99)TcO(3)(nota)](2-) [5](2-) is a very attractive candidate for the development of trisubstituted novel multifunctional radioprobes, (3 + 2)-cycloaddition reactions of [(99)TcO(3)(tacn-ba)](+) [2](+) with 4-vinylbenzenesulfonate (styrene-SO(3)(-)) demonstrated the suitability of monosubstituted tacn derivatives for the new mixed "BFC-(3 + 2)-cycloaddition" approach. Kinetic studies of this reaction lead to the conclusion that the alteration of the electronic structure of the nitrogen donors by, e.g., alkylation can be used to tune the rate of the (3 + 2)-cycloaddition.

  1. Effects of cryopreservation on sperm viability, synthesis of reactive oxygen species, and DNA damage of bovine sperm. (United States)

    Gürler, H; Malama, E; Heppelmann, M; Calisici, O; Leiding, C; Kastelic, J P; Bollwein, H


    The objective was to examine if there are relationships between alterations in sperm viability, reactive oxygen species (ROS) synthesis, and DNA integrity induced by cryopreservation of bovine sperm. Four ejaculates were collected from each of six bulls. Each ejaculate was diluted and divided into two aliquots; one was incubated for 24 hours at 37 °C, and the other frozen, thawed, and incubated for 24 hours at 37 °C. Analyses of quality of sperm were performed after 0, 3, 6, 12, and 24 hours of incubation. Progressive motile sperm was determined with computer assisted sperm analysis. Percentages of plasma membrane- and acrosome-intact sperm, sperm with a high mitochondrial membrane potential, sperm showing a high degree of DNA fragmentation (%DFI), and their reactive oxygen species content were assessed with dichlorofluorescein-diacetate, dihydrorhodamine, diaminofluorescein diacetate, and mitochondrial superoxide indicator using flow cytometry. Although all other sperm parameters showed alterations (P  0.05, 0.91 ± 0.23) in nonfrozen sperm. Cryopreservation induced changes of all sperm parameters (P synthesis of H2O2 showed a similar exponential rise (P synthesis of H2O2 but not to sperm viability and synthesis of other reactive oxygen species.

  2. Structure and reactivity of a mononuclear non-haem iron(III)–peroxo complex


    Cho, Jaeheung; Jeon, Sujin; Wilson, Samuel A.; Liu, Lei V.; Kang, Eun A; Braymer, Joseph J.; Lim, Mi Hee; Hedman, Britt; Hodgson, Keith O.; Valentine, Joan Selverstone; Solomon, Edward I.; Nam, Wonwoo


    Oxygen-containing mononuclear iron species—iron(III)–peroxo, iron(III)–hydroperoxo and iron(IV)–oxo—are key intermediates in the catalytic activation of dioxygen by iron-containing metalloenzymes1–7. It has been difficult to generate synthetic analogues of these three active iron–oxygen species in identical host complexes, which is necessary to elucidate changes to the structure of the iron centre during catalysis and the factors that control their chemical reactivities with substrates. Here ...

  3. Synthesis of magnetite nanoparticles-{beta}-cyclodextrin complex

    Energy Technology Data Exchange (ETDEWEB)

    Cobos Cruz, L.A.; Martinez Perez, C.A. [Instituto de Ingenieria y Tecnologia, Universidad Autonoma de Cd. Juarez, Ave. del Charro 450, Col Partido Romero, C.P. 32360, Cd. Juarez Chih. (Mexico); Monreal Romero, H.A. [Facultad de Odontologia, Universidad Autonoma de Chihuahua, Ciudad Universitaria Campus I, C.P. 31000, Chihuahua, Chi. Mexico (Mexico); Garcia Casillas, P.E. [Instituto de Ingenieria y Tecnologia, Universidad Autonoma de Cd. Juarez, Ave. del Charro 450, Col Partido Romero, C.P. 32360, Cd. Juarez Chih. (Mexico)], E-mail:


    In this work, the synthesis and characterization of a magnetite (M) and {beta}-cyclodextrin (CD) complex is presented. The chemical bonding between the magnetite and CD was studied as evidence of host-guest interaction; therefore the CD works like a reactor with the magnetite inside of it, as consequence the growth of the particle is restricted by the electrostatic interaction of M-CD complex. The particle size of the magnetite-cyclodextrin complex (M-CD) decreased 79.1% with 0.5% of CD. The average particle size of the M-CD complex was 10 nm. The saturation magnetization ({sigma}{sub s}) and intrinsic coercivity (H{sub c}) increased 10% and 20%, respectively. In order to understand how the the CD affects the results obtained, the second derivate of remission function was obtained from the ultraviolet-visible spectra (UV-vis). Fourier transform infrared spectroscopy (FTIR) was used to elucidate the interaction between the magnetite and CD. The thermal analysis was measured by thermogravimetric and differential thermal analysis (TGA-DTA). The magnetic properties, intrinsic coercivity (H{sub c}) and the saturation magnetization were determined by vibrating sample magnetometry (VSM); the size and shape of nanoparticles were determined by scanning electron microscopy (SEM). The identification of phases was made by X-ray diffraction.

  4. Pyrazine-based organometallic complex: synthesis, characterization, and supramolecular chemistry. (United States)

    Bhowmick, Sourav; Chakraborty, Sourav; Das, Atanu; Rajamohanan, P R; Das, Neeladri


    The design, synthesis, and characterization of a new pyrazine-based ditopic platinum(II) organometallic complex are reported. The molecular structure of the organoplatinum pyrazine dipod was determined by single-crystal X-ray crystallography. The potential utility of this organometallic ditopic acceptor as a building block in the construction of neutral metallasupramolecular macrocycles containing the pyrazine motif was explored. Pyrazine motifs containing supramolecules were characterized by multinuclear NMR (including (1)H DOSY), mass spectrometry, and elemental analysis. The geometry of each supramolecular framework was optimized by employing the PM6 semiempirical molecular orbital method to predict its shape and size. The ability of the pyrazine-based organoplatinum complex to act as a host for nitroaromatic guest (2,4-dinitrotoluene and PA) molecules was explored by isothermal titration calorimetry (ITC). The binding stoichiometry and thermodynamic parameters of these host-guest complexation reactions were evaluated using ITC. Theoretical calculations were performed to obtain insight into the binding pattern between the organometallic host and nitroaromatic guests. The preferable binding propensity of the binding sites of complex 1 for both nitroaromatics (PA and 2,4-dinitrotoluene) determined by molecular simulation studies corroborates well with the experimental results as obtained by ITC experiments.

  5. Heart rate complexity: A novel approach to assessing cardiac stress reactivity. (United States)

    Brindle, Ryan C; Ginty, Annie T; Phillips, Anna C; Fisher, James P; McIntyre, David; Carroll, Douglas


    Correlation dimension (D2), a measure of heart rate (HR) complexity, has been shown to decrease in response to acute mental stress and relate to adverse cardiovascular health. However, the relationship between stress-induced changes in D2 and HR has yet to be established. The present studies aimed to assess this relationship systematically while controlling for changes in respiration and autonomic activity. In Study 1 (N = 25) D2 decreased during stress and predicted HR reactivity even after adjusting for changes in respiration rate, and cardiac vagal tone. This result was replicated in Study 2 (N = 162) and extended by including a measure of cardiac sympathetic activity; correlation dimension remained an independent predictor of HR reactivity in a hierarchical linear model containing measures of cardiac parasympathetic and sympathetic activity and their interaction. These results suggest that correlation dimension may provide additional information regarding cardiac stress reactivity above that provided by traditional measures of cardiac autonomic function. © 2015 Society for Psychophysiological Research.

  6. Synthesis of reactive nucleic acid analogues and their application for the study of structure and functions of biopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Kanevskii, Igor' E; Kuznetsova, Svetlana A [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)


    Data on the synthesis of reactive derivatives of nucleic acid analogues and their application for the study of structure and functions of biopolymers are generalised. The main types of such analogues including photoactivated reagents containing azidoaryl, halogeno, and thiol groups, psoralen and its derivatives, platinum-based reagents, and nucleic acid analogues containing substituted pyrophosphate or acyl phosphate internucleotide groups are presented. The mechanisms of interaction of these compounds with proteins and nucleic acids are considered. The prospects for the in vivo application of reactive nucleic acids in various systems are discussed. The bibliography includes 76 references.

  7. Ring-Shaped Phosphinoamido-Magnesium-Hydride Complexes: Syntheses, Structures, Reactivity, and Catalysis. (United States)

    Fohlmeister, Lea; Stasch, Andreas


    A series of magnesium(II) complexes bearing the sterically demanding phosphinoamide ligand, L(-) =Ph2 PNDip(-) , Dip=2,6-diisopropylphenyl, including heteroleptic magnesium alkyl and hydride complexes are described. The ligand geometry enforces various novel ring and cluster geometries for the heteroleptic compounds. We have studied the stoichiometric reactivity of [(LMgH)4 ] towards unsaturated substrates, and investigated catalytic hydroborations and hydrosilylations of ketones and pyridines. We found that hydroborations of two ketones with pinacolborane using various Mg precatalysts is very rapid at room temperature with very low catalyst loadings, and ketone hydrosilylation using phenylsilane is rapid at 70 °C. Our studies point to an insertion/σ-bond metathesis catalytic cycle of an in situ formed "MgH2 " active species.

  8. Modeling the surface tension of complex, reactive organic-inorganic mixtures

    Directory of Open Access Journals (Sweden)

    A. N. Schwier


    Full Text Available Atmospheric aerosols can contain thousands of organic compounds which impact aerosol surface tension, affecting aerosol properties such as cloud condensation nuclei (CCN ability. We present new experimental data for the surface tension of complex, reactive organic-inorganic aqueous mixtures mimicking tropospheric aerosols. Each solution contained 2–6 organic compounds, including methylglyoxal, glyoxal, formaldehyde, acetaldehyde, oxalic acid, succinic acid, leucine, alanine, glycine, and serine, with and without ammonium sulfate. We test two surface tension models and find that most reactive, complex, aqueous organic mixtures which do not contain salt are well-described by a weighted Szyszkowski–Langmuir (S–L model which was first presented by Henning et al. (2005. Two approaches for modeling the effects of salt were tested: (1 the Tuckermann approach (an extension of the Henning model with an additional explicit salt term, and (2 a new implicit method proposed here which employs experimental surface tension data obtained for each organic species in the presence of salt used with the Henning model. We recommend the use of method (2 for surface tension modeling because the Henning model (using data obtained from organic-inorganic systems and Tuckermann approach provide similar modeling fits and goodness of fit (χ2 values, yet the Henning model is a simpler and more physical approach to modeling the effects of salt, requiring less empirically determined parameters.

  9. Scaling up complex interventions: insights from a realist synthesis. (United States)

    Willis, Cameron D; Riley, Barbara L; Stockton, Lisa; Abramowicz, Aneta; Zummach, Dana; Wong, Geoff; Robinson, Kerry L; Best, Allan


    Preventing chronic diseases, such as cancer, cardiovascular disease and diabetes, requires complex interventions, involving multi-component and multi-level efforts that are tailored to the contexts in which they are delivered. Despite an increasing number of complex interventions in public health, many fail to be 'scaled up'. This study aimed to increase understanding of how and under what conditions complex public health interventions may be scaled up to benefit more people and populations.A realist synthesis was conducted and discussed at an in-person workshop involving practitioners responsible for scaling up activities. Realist approaches view causality through the linkages between changes in contexts (C) that activate mechanisms (M), leading to specific outcomes (O) (CMO configurations). To focus this review, three cases of complex interventions that had been successfully scaled up were included: Vibrant Communities, Youth Build USA and Pathways to Education. A search strategy of published and grey literature related to each case was developed, involving searches of relevant databases and nominations from experts. Data extracted from included documents were classified according to CMO configurations within strategic themes. Findings were compared and contrasted with guidance from diffusion theory, and interpreted with knowledge users to identify practical implications and potential directions for future research.Four core mechanisms were identified, namely awareness, commitment, confidence and trust. These mechanisms were activated within two broad scaling up strategies, those of renewing and regenerating, and documenting success. Within each strategy, specific actions to change contexts included building partnerships, conducting evaluations, engaging political support and adapting funding models. These modified contexts triggered the identified mechanisms, leading to a range of scaling up outcomes, such as commitment of new communities, changes in relevant

  10. New arylruthenium(II) complexes of the P,C,P'-Coordinating terdentate monoanionic aryl ligands [C6H2(CH2PPh2)2-2,6-R-4]- (PCP-R-4; R = Ph, H). Synthesis of 16-electron species [RuIIX(PCP-R-4)(PPh3)] (X = Cl, L, OTf) and their reactivity toward the neutral terdentate N-donor ligand 2,2':6',2''-terpyridine (terpy)

    NARCIS (Netherlands)

    Koten, G. van; Karlen, T.; Dani, P.; Grove, D.M.; Steenwinkel, P.


    The synthesis and characterization of new, five-coordinate, diamagnetic, 16-electron arylruthenium(II) complexes [RuIIX{C6H2(CH2PPh2)2-2,6-R-4}(PPh3)] (1, X = Cl, R = H; 2, X = Cl, R = Ph; 3, X = OSO2CF3, R = H; 4, X = I, R = H) are described. These coordinatively unsaturated complexes contain a

  11. Synthesis and characterization of phosphorescent platinum complexes containing phenylpyridazine

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Jin; Kang, Seok; Lee, Seung Hee; Hwang, Kwang Jin; Park, Noh Kil; Kim, Young Sik


    Synthesis and characterization of a series of square planar Pt(II)-phenylpyridazine complexes are reported. The complexes have the general structure of (C-N)Pt(O-O), where HC-N is 3-phenyl-pyridazine (ppdz), 3-(3'-trifluoromethylphenyl)pyridazine (3'tfmppdz), 3-(3'-methoxyphenyl)-pyridazine (3'meoppdz), 3-(4'-methoxyphenyl)pyridazine (4'meoppdz), or 3-phenyl-6-chloro-pyridazine (6Clppdz) and HO-O is acetylacetone (Hacac). Reaction of K{sub 2}PtCl{sub 4} with a HC-N ligand forms the dimer, (C-N)Pt({mu}-Cl){sub 2}Pt(C-N), which is cleaved with Hacac to give the corresponding monomer, (C-N)Pt(O-O). The emission characteristics of these complexes are governed by the substituents of the cyclometalating ligands, showing emission {lambda}{sub max} values from 508 to 610 nm. Strong spin-orbit coupling of the platinum atom allows for the formally forbidden mixing of the {sup 1}MLCT with the {sup 3}MCLT and {sup 3}({pi}-{pi}*) states.

  12. Towards the new heterocycle based molecule: Synthesis, characterization and reactivity study (United States)

    Murthy, P. Krishna; Sheena Mary, Y.; Suneetha, V.; Panicker, C. Yohannan; Armaković, Stevan; Armaković, Sanja J.; Giri, L.; Suchetan, P. A.; Van Alsenoy, C.


    4-Chloro-2-(3-fluorophenyl)-2,3-dihydro-1H-pyrrolo[3,4-c]pyridin-1-one (CFPDPPO) have been synthesized by hydride transfer from Et3SiH to carbenium ions(reduction reaction), which is formed by reaction between 4-chloro-2-(3-fluorophenyl)-3-hydroxy-2,3-dihydro-1H-pyrrolo[3,4-c]pyridin-1-one with TFA, the single crystals were grown in acetonitrile by slow evaporation technique at room temperature and characterized by single crystal X-ray diffraction, FT-IR, FT-Raman, 1H NMR, 13C NMR and ESI-MS. The experimental vibrational spectra were compared with the calculated spectra and each vibrational wavenumber was assigned on the basis of potential energy distribution (PED). Gauge-including atomic orbital 1H NMR and 13C NMR chemical shifts calculations were carried out and compared with experimental data. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analysed using NBO analysis. First hyperpolarizability is calculated in order to find its role in non-linear optics. Besides molecular electrostatic potential (MEP), global reactivity descriptors, thermodynamic properties, and Mullikan charge analysis of the title compound were computed with the same method in gas phase, theoretically. Further, employing combination of DFT calculations and molecular dynamics (MD) simulations, we have investigated in detail reactive properties of the title molecule. Investigation of local reactive properties encompassed calculations of average local ionization energies (ALIE) and Fukui functions. Stability in water has been investigated by calculations of radial distribution functions (RDF), while sensitivity towards the mechanism of autoxidation has been investigated by calculations of bond dissociation energies (BDE). The docked ligand forms a stable complex with human alpha9 nicotinic acetylcholine receptor antagonist and can be a lead

  13. Synthesis of Alkaline-Soluble Cellulose Methyl Carbamate Using a Reactive Deep Eutectic Solvent. (United States)

    Sirviö, Juho Antti; Heiskanen, Juha P


    This study presents the use of a reactive deep eutectic solvent (DES) for the chemical modification of wood cellulose fibers. DES based on dimethylurea and ZnCl2 was used to synthetize cellulose methyl carbamate (CMeC). This synthesis was performed at elevated temperature under solvent-free conditions. Chemical characterization based on FTIR and NMR indicated that methyl carbamate was successfully introduced to cellulose, and a degree of substitution (DS) of 0.17 was obtained after 3 h of reaction at 150 °C. The product with a DS of 0.17 exhibited good alkaline solubility (in 3 % NaOH solution) after freeze-thawing, whereas the original cellulose fibers were practically insoluble even in 9 % NaOH. As dimethylurea can be produced from CO2 , this method can be used as a sustainable way to obtain novel cellulose materials with desirable properties for use in a wide range of applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Synthesis, and Investigation of the Reactive Oxygen Species of a Novel Cyclicpeptide-2,6-dimethoxyhydroquinone-3- mercaptoacetic Acid Conjugate

    Institute of Scientific and Technical Information of China (English)


    In this paper, we report the synthesis of a potential anti-cancer agent: Cyclo[Val Lys(DMQ-MA)-Gaba]. The cytotoxic agent conjugated to the N-terminal and the ξ-amino group of lysine of the tripeptide is 2,6-dimethoxyhydroquinone-3-mercaptoacetic acid (DMQ-MA). By employing the rhodamine B degradation method and ESR spectra, we testify the reactive oxygen species---hydroxyl radicals produced by the drug.

  15. Stability and Reactivity of Cyclometallated Naphthylamine Complexes in Pd-C Bond Insertion Reactions with Coordinated Alkynylphosphanes

    KAUST Repository

    Chen, Shuli


    Phenylbis(phenylethynyl)phosphane PhP(C≡CPh)2 coordinates regiospecifically to the α-methyl-chiral ortho-platinated and -palladated naphthylamine units at the positions trans to the nitrogen donors. The P→Pt coordination bond is kinetically inert, whereas the P→Pd bond is labile. Upon heating of these phosphane complexes at 70 °C, one of the C≡C bonds in the coordinated PhP(C≡CPh)2 was activated towards an intermolecular Pd-C bond insertion reaction with an external ortho-palladated naphthylamine ring. No intramolecular insertion reaction occurred. In contrast to its palladium analogue, the ortho-platinated ring is not reactive towards coordinated PhP(C≡CPh)2, although it can promote the Pd-C bond insertion reaction. However, despite the high kinetic stability of the P→Pt coordination, the organoplatinum unit is a noticeably weaker activator than its organopalladium counterpart. The chirality of the reacting ortho-metallated naphthylamine ligand exhibited high stereochemical influence on the formation of the new stereogenic phosphorus center during the course of these C-C bond-formation reactions. The coordination chemistry and the absolute stereochemistry of the dimetallic products were determined by single-crystal X-ray crystallographic analysis. The asymmetric monoinsertion of PhP(C≡CPh)2 coordinated to a cyclometallated N,N-dimethyl naphthyl/benzylamine template into the Pd-C bonds of N,N-dimethylnaphthylamine palladacycles has been demonstrated for the synthesis of a variety of new P-stereogenic homo- or heterodimetallic complexes. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


    Institute of Scientific and Technical Information of China (English)

    Lai-bao Zhang; Yi-xian Wu; Peng Zhou; Guan-ying Wu; Wan-tai Yang; Ding-sheng Yu


    The selective cationic polymerization of isobutylene (IB) initiated by a BF3·cyclohexanol (CL) complex was carried out from the mixed C4 fraction feed containing the 4C saturated and unsaturated hydrocarbons at -20℃. The effects of CL concentration, BF3 concentration, solvent for preparing BF3·CL complex and polymerization time on the chemical structure of end groups, number-average molecular weight (Mn) and molecular weight distribution (MWD, Mw/Mn) of the resulting polymers were investigated. The experimental results indicate that the BF3·CL complex initiating system exhibited an extremely high selectivity toward the cationic polymerization of IB in the mixed C4 fraction feed and low molecular weight (Mn = 900-3600) polyisobutylenes (PIBs) with large proportion of exo-double bond end groups were obtained. The exo-double bond content in PIB chain ends increased by increasing CL concentration or by decreasing solvent polarity in initiating system, BF3 concentration and polymerization time. The Mn and MWD of the resulting PIBs were dependent on the concentrations of CL and BF3. Highly reactive PIBs with around 90 mol% of exo-double bonds were successfully synthesized by the selective polymerization of IB from the mixed C4 fraction feed, providing a potentially practical process for its simplicity and low costs.

  17. Solvent dependent reactivities of di-, tetra- and hexanuclear manganese complexes: syntheses, structures and magnetic properties. (United States)

    Yang, Hua; Cao, Fan; Li, Dacheng; Zeng, Suyuan; Song, You; Dou, Jianmin


    An unusual solvent effect on the synthesis of five manganese complexes [Mn2(L1)2(Py)4](), [Mn2(L1)2(DMSO)4](), [Mn4(L2)4(OH)4](), [Mn4(L3)2(DMSO)7(H2O)](), and [Mn6O2(L4)4(OAc)2(OMe)2(DMSO)4]·MeOH] (), (H3L1 = 5-(2-oxyphenyl)-pyrazole-3-carboxylic acid; H2L2 = 5-(2-oxyphenyl)-pyrazole-3-carboxylic acid amide; H4L3 = di-[5-(2-oxyphenyl)-pyrazole]-3-hydroxamic ether; and H2L4 = 5-(2-oxyphenyl)-pyrazole-3-carboxylic acid methyl ester) has been reported. Five complexes have been characterized by X-ray single crystal diffraction, IR, element analysis, thermogravimetric analysis and UV-vis spectra. The analysis reveals that complexes and are isostructural with a bimetallic six-membered ring and L1 from the decomposition of the original H4ppha (H4ppha = 5-(2-hydroxyphenyl)-pyrazole-3-hydroxamic acid) ligand. Complexes and are two tetranuclear clusters, and possesses an aza12-metallacrown-4 core with L2 from the amide functionalization of the decomposition L1; while represents a novel linear [Mn4N8O2] core with L3 from the condensation of L1 and H4ppha. Complex is the first Mn6 cluster linked by two stacked, off-set 8-azametallacrown-3 subunits with [M-N-N-M-N-N-M-O] connectivity, and L4 derived from the esterification of L1. The magnetic behaviour of complexes show the dominant antiferromagnetic interactions between metal centers, whereas complex further reveals the coexistence of antiferromagnetic and ferromagnetic interactions, and slow magnetic relaxation at T < 6 K with S = 4 ground state, as well as field induced magnetization saturation.

  18. Synthesis of Titanium Dioxide Nanocrystals with Controlled Crystal- and Micro-structures from Titanium Complexes


    Makoto Kobayashi; Hideki Kato; Masato Kakihana


    Selective synthesis of titanium dioxide (TiO2) polymorphs including anatase, rutile, brookite and TiO2(B) by solvothermal treatment of water-soluble titanium complexes is described with a special focus on their morphological control. The utilization of water-soluble titanium complexes as a raw material allowed us to employ various additives in the synthesis of TiO2. As a result, the selective synthesis of the polymorphs, as well as diverse morphological control, was achieved.

  19. Synthesis and Characterization of Binuclear Schiff Base Complexes of Nickel, Copper, and Manganese. (United States)



  20. Significance of Lipid-Derived Reactive Aldehyde-Specific Immune Complexes in Systemic Lupus Erythematosus (United States)

    Wang, Gangduo; Pierangeli, Silvia S.; Willis, Rohan; Gonzalez, Emilio B.; Petri, Michelle; Khan, M. Firoze


    Even though systemic lupus erythematosus (SLE) is associated with high morbidity and mortality rates among young and middle-aged women, the molecular mechanisms of disease pathogenesis are not fully understood. Previous studies from our laboratory suggested an association between oxidative stress and SLE disease activity (SLEDAI). To further assess the role of reactive oxygen species (ROS) in SLE, we examined the contribution of lipid-derived reactive aldehydes (LDRAs)-specific immune complexes in SLE. Sera from 60 SLE patients with varying SLEDAI and 32 age- and gender- matched healthy controls were analyzed for oxidative stress and related markers. Patients were divided into two groups based on their SLEDAI scores (<6 and ≥ 6). Both SLEDAI groups showed higher serum 4-hydroxynonenal (HNE)-/malondialdehyde (MDA)-protein adducts and their specific immune complexes (HNE-/MDA-specific ICs) together with IL-17 than the controls, but the levels were significantly greater in the high SLEDAI (≥ 6) group. Moreover, the serum levels of anti-oxidant enzymes Cu/Zn superoxide dismutase (SOD) and catalase (CAT) were significantly reduced in both patient groups compared to controls. Remarkably, for the first time, our data show that increased HNE-/MDA-specific ICs are positively associated with SLEDAI and elevated circulating immune complexes (CICs), suggesting a possible causal relationship among oxidative stress, LDRA-specific ICs and the development of SLE. Our findings, apart from providing firm support to an association between oxidative stress and SLE, also suggest that these oxidative stress markers, especially the HNE-/MDA-specific ICs, may be useful in evaluating the prognosis of SLE as well as in elucidating the mechanisms of disease pathogenesis. PMID:27749917

  1. Synthesis of Orthogonally Reactive FK506 Derivatives via Olefin Cross Metathesis (United States)

    Marinec, Paul S.; Evans, Christopher G.; Gibbons, Garrett S.; Tarnowski, Malloree A.; Overbeek, Daniel L.; Gestwicki, Jason E.


    Chemical inducers of dimerization (CIDs) are employed in a wide range of biological applications, to control protein localization, modulate protein-protein interactions and improve drug lifetimes. These bifunctional chemical probes are assembled from two synthetic modules, which each provide affinity for a distinct protein target. FK506 and its derivatives are often employed as modules in the syntheses of these bifunctional constructs, owing to the abundance and favorable distribution of their target, FK506-binding protein (FKBP). However, the structural complexity of FK506 necessitates multi-step syntheses and/or multiple protection-deprotection schemes prior to installation into CIDs. In this work, we describe an efficient, one-step synthesis of FK506 derivatives through a selective, microwave-accelerated, cross metathesis diversification step of the C39 terminal alkene. Using this approach, FK506 is modified with an array of functional groups, including primary amines and carboxylic acids, which make the resulting derivatives suitable for the modular assembly of CIDs. To illustrate this idea, we report the synthesis of a heterobifunctional HIV protease inhibitor. PMID:19643614

  2. Electronic Structure and Reactivity of a Well-Defined Mononuclear Complex of Ti(II). (United States)

    Wijeratne, Gayan B; Zolnhofer, Eva M; Fortier, Skye; Grant, Lauren N; Carroll, Patrick J; Chen, Chun-Hsing; Meyer, Karsten; Krzystek, J; Ozarowski, Andrew; Jackson, Timothy A; Mindiola, Daniel J; Telser, Joshua


    A facile and high-yielding protocol to the known Ti(II) complex trans-[(py)4TiCl2] (py = pyridine) has been developed. Its electronic structure has been probed experimentally using magnetic susceptibility, magnetic circular dichroism, and high-frequency and high-field electron paramagnetic resonance spectroscopies in conjunction with ligand-field theory and computational methods (density functional theory and ab initio methods). These studies demonstrated that trans-[(py)4TiCl2] has a (3)Eg ground state (dxy(1)dxz,yz(1) orbital occupancy), which, as a result of spin–orbit coupling, yields a ground-state spinor doublet that is EPR active, a first excited-state doublet at ∼60 cm(–1), and two next excited states at ∼120 cm(–1). Reactivity studies with various unsaturated substrates are also presented in this study, which show that the Ti(II) center allows oxidative addition likely via formation of [Ti(η(2)-R2E2)Cl2(py)n] E = C, N intermediates. A new Ti(IV) compound, mer-[(py)3(η(2)-Ph2C2)TiCl2], was prepared by reaction with Ph2C2, along with the previously reported complex trans-(py)3Ti═NPh(Cl)2, from reaction with Ph2N2. Reaction with Ph2CN2 also yielded a new dinuclear Ti(IV) complex, [(py)2(Cl)2Ti(μ2:η(2)-N2CPh2)2Ti(Cl)2], in which the two Ti(IV) ions are inequivalently coordinated. Reaction with cyclooctatetraene (COT) yielded a new Ti(III) complex, [(py)2Ti(η(8)-COT)Cl], which is a rare example of a mononuclear “piano-stool” titanium complex. The complex trans-[(py)4TiCl2] has thus been shown to be synthetically accessible, have an interesting electronic structure, and be reactive toward oxidation chemistry.

  3. Synthesis of Stable Diarylpalladium(II) Complexes: Detailed Study of the Aryl-Aryl Bond-Forming Reductive Elimination. (United States)

    Gensch, Tobias; Richter, Nils; Theumer, Gabriele; Kataeva, Olga; Knölker, Hans-Joachim


    The synthesis of diarylpalladium(II) complexes by twofold aryl C-H bond activation was developed. These intermediates of oxidative cyclization reactions are stabilized by chelation with acetyl groups while still maintaining sufficient reactivity to study their reductive elimination. Four distinct triggers were found for the reductive elimination of these complexes to dibenzofurans and carbazoles. Thermal elimination occurs at very high temperatures, whereas ligand-promoted and oxidatively induced reductive eliminations proceed readily at room temperature. Under these conditions, no isomerization occurs. In contrast, weak Brønsted acids, such as acetic acid, lead to a sequence of proto-demetalation, isomerization to a κ(3) -diarylpalladium(II) complex, and reductive elimination to non-symmetrical cyclization products.

  4. Synthesis, structures, and dearomatization by deprotonation of iron complexes featuring bipyridine-based PNN pincer ligands. (United States)

    Zell, Thomas; Langer, Robert; Iron, Mark A; Konstantinovski, Leonid; Shimon, Linda J W; Diskin-Posner, Yael; Leitus, Gregory; Balaraman, Ekambaram; Ben-David, Yehoshoa; Milstein, David


    The synthesis and characterization of new iron pincer complexes bearing bipyridine-based PNN ligands is reported. Three phosphine-substituted pincer ligands, namely, the known (t)Bu-PNN (6-((di-tert-butylphosphino)methyl)-2,2'-bipyridine) and the two new (i)Pr-PNN (6-((di-iso-propylphosphino)methyl)-2,2'-bipyridine) and Ph-PNN (6-((diphenylphosphino)methyl)-2,2'-bipyridine) ligands were synthesized and studied in ligation reactions with iron(II) chloride and bromide. These reactions lead to the formation of two types of complexes: mono-chelated neutral complexes of the type [(R-PNN)Fe(X)2] and bis-chelated dicationic complexes of the type [(R-PNN)2Fe](2+). The complexes [(R-PNN)Fe(X)2] (1: R = (t)Bu, X = Cl, 2: R = (t)Bu, X = Br, 3: R = (i)Pr, X = Cl, and 4: R = (i)Pr, X = Br) are readily prepared from reactions of FeX2 with the free R-PNN ligand in a 1:1 ratio. Magnetic susceptibility measurements show that these complexes have a high-spin ground state (S = 2) at room temperature. Employing a 2-fold or higher excess of (i)Pr-PNN, diamagnetic hexacoordinated dicationic complexes of the type [((i)Pr-PNN)2Fe](X)2 (5: X = Cl, and 6: X = Br) are formed. The reactions of Ph-PNN with FeX2 in a 1:1 ratio lead to similar complexes of the type [(Ph-PNN)2Fe](FeX4) (7: X = Cl, and 8: X = Br). Single crystal X-ray studies of 1, 2, 4, 6, and 8 do not indicate electron transfer from the Fe(II) centers to the neutral bipyridine unit based on the determined bond lengths. Density functional theory (DFT) calculations were performed to compare the relative energies of the mono- and bis-chelated complexes. The doubly deprotonated complexes [(R-PNN*)2Fe] (9: R = (i)Pr, and 10: R = Ph) were synthesized by reactions of the dicationic complexes 6 and 8 with KO(t)Bu. The dearomatized nature of the central pyridine of the pincer ligand was established by X-ray diffraction analysis of single crystals of 10. Reactivity studies show that 9 and 10 have a slightly different behavior in

  5. Selective organic synthesis through generation and reactivity control of hyper-coordinate metal species. (United States)

    Hiyama, Tamejiro


    This paper is a review of my 40 years of research at Kyoto, Sagamihara, and Yokohama, all based on the generation of hyper-coordinate metal species such as ate complexes and pentacoordinate silicates. The topics are: (i) carbenoid reagents for carbon-carbon bond-forming reactions, (ii) nucleophilic substitution at acetal carbons using aluminate reagents, (iii) preparation of magnesium enolates and its reaction with nitriles, (iv) Cr(II) reagents for reduction of organic halides and highly selective carbon-carbon bond formation, (v) organic synthesis with organosilion reagents/fluoride ions, (vi) cross-coupling reaction of organosilicon compounds, and (vii) silicon-based conjugate addition to alpha,beta-unsaturated carbonyl acceptors.

  6. Selective Synthesis of Manganese/Silicon Complexes in Supercritical Water

    Directory of Open Access Journals (Sweden)

    Jiancheng Wang


    Full Text Available A series of manganese salts (Mn(NO32, MnCl2, MnSO4, and Mn(Ac2 and silicon materials (silica sand, silica sol, and tetraethyl orthosilicate were used to synthesize Mn/Si complexes in supercritical water using a tube reactor. X-ray diffraction (XRD, X-ray photoelectron spectrometer (XPS, transmission electron microscopy (TEM, and scanning electron microscopy (SEM were employed to characterize the structure and morphology of the solid products. It was found that MnO2, Mn2O3, and Mn2SiO4 could be obtained in supercritical water at 673 K in 5 minutes. The roles of both anions of manganese salts and silicon species in the formation of manganese silicon complexes were discussed. The inorganic manganese salt with the oxyacid radical could be easily decomposed to produce MnO2/SiO2 and Mn2O3/SiO2. It is interesting to found that Mn(Ac2 can react with various types of silicon to produce Mn2SiO4. The hydroxyl groups of the SiO2 surface from different silicon sources enhance the reactivity of SiO2.

  7. Synthesis of a new complex Chromium (Ⅲ) 2-mercaptonicotinate

    Institute of Scientific and Technical Information of China (English)

    LI Wei; HAO Er-jun; JIANG Yu-qin


    Chromium is an essential trace element for mammals[1-3].Diabetes is a chronic disease with major health consequence. Studies show that the occurrence of diabetes have great thing to do with the chromium deficient. Almost 40 years after the first report of glucose tolerance factor(GTF)[4]no conclusive evidence for an isolable ,biologically active form of chromium exited. Three materials have been proposed to be the biologically active form of chromium: "glucose tolerance factor", chromium Picolinate and low-molecular-weight chromium-binding substance (LWMCr)[5]So there is potential for the design of new chromium drugs[6].Chromium compounds have been used in medicine for centuries and there is potential for the design of new chromium drugs.2-Mercaptonicotinic acid(MN) displays the interesting biological activity. Chromium( Ⅲ )2-mercaptonicotinate is a common and effective biologically active form of Chromium. The test of biological activity indicated that may be useful in treating of diabetes. In this paper, we reported the The synthesis route is as follow:The structure of the complex has been characterized by IR, elemental analysis, MS,atomic absorption spectroscopy, X-ray powder diffraction and TG-DTA analysis.They indicate that the structure of Chromium 2-mercaptonicotinate.HPLC is used for determination of the purity. Studies show that the complex has a good biological activity for supplement tiny dietary chromium,lowering blood glucose levels, lowering serum lipid levels and increasing lean body mass.

  8. Reactivity studies on [Cp'FeI]2: monomeric amido, phenoxo, and alkyl complexes. (United States)

    Walter, Marc D; White, Peter S


    A series of monomeric mono(cyclopentadienyl) iron amido, phenoxo, and alkyl complexes were synthesized, and their structure and reactivity are presented. The iron(II) centers in these 14VE one-legged piano stool complexes are high spin (S = 2) in solid state and solution independent of solvent. The silylamide compound [Cp'FeN(SiMe(3))(2)] (2a, Cp' = 1,2,4-(Me(3)C)(3)C(5)H(2)) is an excellent starting material for the reaction with more acidic substrates such as phenols. Sterically encumbered phenols 2,6-(Me(3)C)(2)(4-R)C(6)H(2)OH (R = H, Me, and tBu) were investigated. In all cases monomeric iron phenoxo half-sandwich complexes [Cp'FeOR'] (4-R) are initially formed. Rearrangement of 4-R to the diamagnetic oxocyclohexadienyl complex [Cp'Fe(η(5)-O═C(6)H(2)R'(2)R")] (5-R) is observed for 2,6-(Me(3)C)(2)(4-R)C(6)H(2)OH (R = H and Me) and the Gibbs free enthalpy of activation (ΔG(‡)) was determined. In contrast this rearrangement is inhibited when the 4-position is blocked by a tBu group. Removing the steric bulk from the 2,6-positions leads to the formation of a μ-phenoxo dimer, [Cp'Fe(μ-OC(6)H(3)tBu(2)-3,5)](2) (5). Density functional theory (DFT) was used to further elucidate the structure-reactivity relationship in these molecules. The one-legged piano stool anilido complex [Cp'Fe(NHC(6)H(2)tBu(3)-2,4,6)] (7) is not accessible via acid-base reaction between 2a and H(2)NC(6)H(2)tBu(3)-2,4,6, but can be prepared by conventional salt metathesis reaction from [Cp'FeI](2) and [Li(NHC(6)H(2)tBu(3)-2,4,6)(OEt(2))](2). In contrast, reaction of 2a with Ph(2)NH yields the bimetallic [Cp'Fe(N,C-κ(1),η(5)-C(6)H(5)NPh)Fe(N-κ(1)-NPh(2))Cp'] (8) which combines two iron centers in the same oxidation state (+2), but different spin-states (S = 0 and S = 2) which is reflected in very different Cp(cent)-Fe distances of 1.68 and 2.04 Å, respectively. A monomeric iron alkyl half-sandwich complex [Cp'FeCH(SiMe(3))(2)] (9) was prepared that exhibits no reactivity toward H(2), C

  9. Highly reactive {001} facets of TiO2-based composites: synthesis, formation mechanism and characterization. (United States)

    Ong, Wee-Jun; Tan, Lling-Lling; Chai, Siang-Piao; Yong, Siek-Ting; Mohamed, Abdul Rahman


    Titanium dioxide (TiO2) is one of the most widely investigated metal oxides due to its extraordinary surface, electronic and catalytic properties. However, the large band gap of TiO2 and massive recombination of photogenerated electron-hole pairs limit its photocatalytic and photovoltaic efficiency. Therefore, increasing research attention is now being directed towards engineering the surface structure of TiO2 at the most fundamental and atomic level namely morphological control of {001} facets in the range of microscale and nanoscale to fine-tune its physicochemical properties, which could ultimately lead to the optimization of its selectivity and reactivity. The synthesis of {001}-faceted TiO2 is currently one of the most active interdisciplinary research areas and demonstrations of catalytic enhancement are abundant. Modifications such as metal and non-metal doping have also been extensively studied to extend its band gap to the visible light region. This steady progress has demonstrated that TiO2-based composites with {001} facets are playing and will continue to play an indispensable role in the environmental remediation and in the search for clean and renewable energy technologies. This review encompasses the state-of-the-art research activities and latest advancements in the design of highly reactive {001} facet-dominated TiO2via various strategies, including hydrothermal/solvothermal, high temperature gas phase reactions and non-hydrolytic alcoholysis methods. The stabilization of {001} facets using fluorine-containing species and fluorine-free capping agents is also critically discussed in this review. To overcome the large band gap of TiO2 and rapid recombination of photogenerated charge carriers, modifications are carried out to manipulate its electronic band structure, including transition metal doping, noble metal doping, non-metal doping and incorporating graphene as a two-dimensional (2D) catalyst support. The advancements made in these aspects are

  10. The effect of reactive oxygen species on the synthesis of prostanoids from arachidonic acid. (United States)

    Korbecki, J; Baranowska-Bosiacka, I; Gutowska, I; Chlubek, D


    Reactive oxygen species (ROS), such as hydrogen peroxide, superoxide anion radical or hydroxyl radical, play an important role in inflammation processes as well as in transduction of signals from receptors to interleukin -1β (IL-1β), tumor necrosis factor α (TNF-α) or lipopolysaccharides (LPS). NADPH oxidase increases the ROS levels, leading to inactivation of protein phosphatase 1 (PP1), protein phosphatase 2A (PP2A) and protein tyrosine phosphatase (PTP): MAPK phosphatase 1 (MKP-1). Inactivation of phosphatases results in activation of mitogen-activated protein kinase (MAPK) cascades: c-Jun N-terminal kinase (JNK), p38 and extracellular signal-regulated kinase (Erk), which, in turn, activate cytosolic phospholipase A₂ (cPLA₂). ROS cause cytoplasmic calcium influx by activation of phospholipase C (PLC) and phosphorylation of IP₃-sensitive calcium channels. ROS activate nuclear factor κB (NF-κB) via IκB kinase (IKK) through phosphoinositide 3-kinase (PI3K), tumor suppressor phosphatase and tensin homolog (PTEN) and protein kinase B (Akt/PKB) or NF-κB-inducing kinase (NIK). IKK phosphorylates NF-κB α subunit (IκBα) at Ser³². Oxidative stress inactivates NIK and IκB kinase γ subunit/NF-κB essential modulator (IKKγ/NEMO), which might cause activation of NF-κB that is independent on IKK and inhibitor of IκBα degradation, including phosphorylation of Tyr⁴² at IκBα by c-Src and spleen tyrosine kinase (Syk), phosphorylation of the domain rich in proline, glutamic acid, serine and threonine (PEST) sequence by casein kinase II and inactivation of protein tyrosine phosphatase 1B (PTP1B). NF-κB and MAPK cascades-activated transcription factor activator protein 1 (AP-1) and CREB-binding protein (CBP/p300) lead to expression of cytosolic phospholipase A₂ (cPLA₂), cyclooxygenase-2 (COX-2) and membrane-bound prostaglandin E synthase 1 (mPGES-1), and thus to increased release of arachidonic acid and production of prostaglandins, particularly

  11. Reactivity of seventeen- and nineteen-valence electron complexes in organometallic chemistry (United States)

    Stiegman, Albert E.; Tyler, David R.


    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.

  12. Coordination chemistry and reactivity of zinc complexes supported by a phosphido pincer ligand. (United States)

    D'Auria, Ilaria; Lamberti, Marina; Mazzeo, Mina; Milione, Stefano; Roviello, Giuseppina; Pellecchia, Claudio


    The preparation and characterization of new Zn(II) complexes of the type [(PPP)ZnR] in which R = Et (1) or N(SiMe(3))(2) (2) and PPP is a tridentate monoanionic phosphido ligand (PPP-H = bis(2-diphenylphosphinophenyl)phosphine) are reported. Reaction of ZnEt(2) and Zn[N(SiMe(3))(2)](2) with one equivalent of proligand PPP-H produced the corresponding tetrahedral zinc ethyl (1) and zinc amido (2) complexes in high yield. Homoleptic (PPP)(2) Zn complex 3 was obtained by reaction of the precursors with two equivalents of the proligand. Structural characterization of 1-3 was achieved by multinuclear NMR spectroscopy ((1)H, (13)C, and (31)P) and X-ray crystallography (3). Variable-temperature (1)H and (31)P NMR studies highlighted marked flexibility of the phosphido pincer ligand in coordination at the metal center. A DFT calculation on the compounds provided theoretical support for this behavior. The activities of 1 and 2 toward the ring-opening polymerization of ε-caprolactone and of L- and rac-lactide were investigated, also in combination with an alcohol as external chain-transfer agent. Polyesters with controlled molecular parameters (M(n), end groups) and low polydispersities were obtained. A DFT study on ring-opening polymerization promoted by these complexes highlighted the importance of the coordinative flexibility of the ancillary ligand to promote monomer coordination at the reactive zinc center. Preliminary investigations showed the ability of these complexes to promote copolymerization of L-lactide and ε-caprolactone to achieve random copolymers whose microstructure reproduces the composition of the monomer feed.

  13. Structure, reactivity and synthesis of piramidines and their derivates (dihidroperimidines and perimidinones); Estructura, reactividad y sintesis de perimidinas y de sus derivados (dihidroperimidinas y perimifinonas)

    Energy Technology Data Exchange (ETDEWEB)

    Claramunt, R.M.; Dotor, J.; Elguero, J. [Departamento de Quimica Organica, Facultad de Ciencias, UNED, Madrid (Spain)


    This review reports 346 references dealing with structure, reactivity and synthesis of pyrimidines and their derivatives (mainly 2,3-dihidroperimidines, 2-perimidinones and perimidinium salts). Special emphasis has been made on spectroscopy and structural properties as well as on reactivity. 346 refs.

  14. Thiomaltol-Based Organometallic Complexes with 1-Methylimidazole as Leaving Group: Synthesis, Stability, and Biological Behavior. (United States)

    Hackl, Carmen M; Legina, Maria S; Pichler, Verena; Schmidlehner, Melanie; Roller, Alexander; Dömötör, Orsolya; Enyedy, Eva A; Jakupec, Michael A; Kandioller, Wolfgang; Keppler, Bernhard K


    Thiomaltol, a potential S,O-coordinating molecule, has been utilized for the complexation of four different organometallic fragments, yielding the desired Ru(II) , Os(II) , Rh(III) , and Ir(III) complexes having a "piano-stool" configuration. In addition to the synthesis of these compounds with a chlorido leaving group, the analogous 1-methylimidazole derivatives have been prepared, giving rise to thiomaltol-based organometallics with enhanced stability under physiological conditions. The organometallic compounds have been characterized by NMR spectroscopy, elemental analysis, and X-ray diffraction analysis. Their behavior in aqueous solution and their interactions with certain amino acids have been studied by ESI mass spectrometry. Their pH-dependent stability has been investigated by (1) H NMR in aqueous solution, and their cytotoxicity against three different cancer cell lines has been investigated. Furthermore, their capacity as topoisomerase IIα inhibitors as well as their effect on the cell cycle distribution and reactive oxygen species (ROS) generation have been elucidated.

  15. Deficient plastidic fatty acid synthesis triggers cell death by modulating mitochondrial reactive oxygen species. (United States)

    Wu, Jian; Sun, Yuefeng; Zhao, Yannan; Zhang, Jian; Luo, Lilan; Li, Meng; Wang, Jinlong; Yu, Hong; Liu, Guifu; Yang, Liusha; Xiong, Guosheng; Zhou, Jian-Min; Zuo, Jianru; Wang, Yonghong; Li, Jiayang


    Programmed cell death (PCD) is of fundamental importance to development and defense in animals and plants. In plants, a well-recognized form of PCD is hypersensitive response (HR) triggered by pathogens, which involves the generation of reactive oxygen species (ROS) and other signaling molecules. While the mitochondrion is a master regulator of PCD in animals, the chloroplast is known to regulate PCD in plants. Arabidopsis Mosaic Death 1 (MOD1), an enoyl-acyl carrier protein (ACP) reductase essential for fatty acid biosynthesis in chloroplasts, negatively regulates PCD in Arabidopsis. Here we report that PCD in mod1 results from accumulated ROS and can be suppressed by mutations in mitochondrial complex I components, and that the suppression is confirmed by pharmaceutical inhibition of the complex I-generated ROS. We further show that intact mitochondria are required for full HR and optimum disease resistance to the Pseudomonas syringae bacteria. These findings strongly indicate that the ROS generated in the electron transport chain in mitochondria plays a key role in triggering plant PCD and highlight an important role of the communication between chloroplast and mitochondrion in the control of PCD in plants.

  16. Synthesis of acetyl coenzyme A by carbon monoxide dehydrogenase complex from acetate-grown Methanosarcina thermophila.


    Abbanat, D R; Ferry, J G


    The carbon monoxide dehydrogenase (CODH) complex from Methanosarcina thermophila catalyzed the synthesis of acetyl coenzyme A (acetyl-CoA) from CH3I, CO, and coenzyme A (CoA) at a rate of 65 nmol/min/mg at 55 degrees C. The reaction ended after 5 min with the synthesis of 52 nmol of acetyl-CoA per nmol of CODH complex. The optimum temperature for acetyl-CoA synthesis in the assay was between 55 and 60 degrees C; the rate of synthesis at 55 degrees C was not significantly different between pHs...

  17. Studies on solid phase synthesis,characterization and fluorescent property of the new rare earth complexes


    Shi, Jianwei; Xiaoxu TENG; Wang, Linling; Long, Rong


    Rare earth-β-diketone ligand complex luminescent material has stable chemical properties and excellent luminous property. Using europium oxide and (γ-NTA) as raw materials, novel rare earth-β-dione complexes are synthesized by solid state coordination chemistry. The synthesis temperature and milling time are discussed for optimization. Experimental results show that the suitable reaction situation is at 50 ℃ and 20 h for solid-phase synthesis. The compositions and structures of the complexes...

  18. Combinatorial effects of continuous protein synthesis, ERK-signaling, and reactive oxygen species on induction of cellular senescence. (United States)

    Takauji, Yuki; En, Atsuki; Miki, Kensuke; Ayusawa, Dai; Fujii, Michihiko


    Mammalian cells, when treated with sub-lethal doses of genotoxic stresses, slow down DNA synthesis but continue protein synthesis. Thus, these cells show an accumulation of proteins and undergo unbalanced growth. In the previous studies, we have shown that HeLa cells treated with excess thymidine or camptothecin undergo unbalanced growth, and prolonged unbalanced growth causes induction of cellular senescence, which is suppressed by restriction of protein synthesis or inhibition of ERK-signaling. In this study, we found that restriction of protein synthesis, inhibition of ERK-signaling, and elimination of reactive oxygen species showed a combinatorial effect on suppression of cellular senescence induced by excess thymidine or camptothecin. Of these, restriction of protein synthesis most effectively suppressed cellular senescence. Importantly, a similar combinatorial effect was observed in replicative senescence in normal human diploid fibroblasts. Our findings suggested that various stresses were cumulatively involved in cellular senescence, and suppression of cellular senescence was improved by combining the treatments that reduce the stresses.

  19. Nucleophilic reactivity and electrocatalytic reduction of halogenated organic compounds by nickel o-phenylenedioxamidate complexes. (United States)

    Das, Siva Prasad; Ganguly, Rakesh; Li, Yongxin; Soo, Han Sen


    A growing number of halogenated organic compounds have been identified as hazardous pollutants. Although numerous advanced oxidative processes have been developed to degrade organohalide compounds, reductive and nucleophilic molecular approaches to dehalogenate organic compounds have rarely been reported. In this manuscript, we employ nickel(ii)-ate complexes bearing the o-phenylenebis(N-methyloxamide) (Me2opba) tetraanionic ligand as nucleophilic reagents that can react with alkyl halides (methyl up to the bulky isobutyl) by O-alkylation to give their respective imidate products. Four new nickel(ii) complexes have been characterized by X-ray crystallography, and the salient structural parameters and FT-IR vibrational bands (∼1655 cm(-1)) concur with their assignment as the imidate tautomeric form. To the best of our knowledge, this is the first report on the nucleophilic reactivity of Ni(II)(Me2opba) with halogenated organic compounds. The parent nickel(ii) Me2opba complex exhibits reversible electrochemical oxidation and reduction behavior. As a proof of concept, Ni(II)(Me2opba) and its alkylated congeners were utilized for the electrocatalytic reduction of chloroform, as a representative, simple polyhalogenated organic molecule that could arise from the oxidative treatment of organic compounds by chlorination. Modest turnover numbers of up to 6 were recorded, with dichloromethane identified as one of the possible products. Future efforts are directed towards bulkier -ate complexes that possess metal-centered instead of ligand-centered nucleophilic activity to create more effective electrocatalysts for the reduction of halogenated organic compounds.

  20. Alpha-tricalcium phosphate (α-TCP): solid state synthesis from different calcium precursors and the hydraulic reactivity. (United States)

    Cicek, Gulcin; Aksoy, Eda Ayse; Durucan, Caner; Hasirci, Nesrin


    The effects of solid state synthesis process parameters and primary calcium precursor on the cement-type hydration efficiency (at 37 °C) of α-tricalcium phosphate (Ca(3)(PO(4))(2) or α-TCP) into hydroxyapatite (Ca(10-x)HPO(4)(PO(4))(6-x)(OH)(2-x) x = 0-1, or HAp) have been investigated. α-TCP was synthesized by firing of stoichiometric amount of calcium carbonate (CaCO(3)) and monetite (CaHPO(4)) at 1150-1350 °C for 2 h. Three commercial grade CaCO(3) powders of different purity were used as the starting material and the resultant α-TCP products for all synthesis routes were compared in terms of the material properties and the reactivity. The reactant CaHPO(4) was also custom synthesized from the respective CaCO(3) source. A low firing temperature in the range of 1150-1350°C promoted formation of β-polymorph as a second phase in the resultant TCP. Meanwhile, higher firing temperatures resulted in phase pure α-TCP with poor hydraulic reactivity. The extension of firing operation also led to a decrease in the reactivity. It was found that identical synthesis history, morphology, particle size and crystallinity match between the α-TCPs produced from different CaCO(3) sources do not essentially culminate in products exhibiting similar hydraulic reactivity. The changes in reactivity are arising from differences in the trace amount of impurities found in the CaCO(3) precursors. In this regard, a correlation between the observed hydraulic reactivities and the impurity content of the CaCO(3) powders--as determined by inductively coupled plasma mass spectrometry--has been established. A high level of magnesium impurity in the CaCO(3) almost completely hampers the hydration of α-TCP. This impurity also favors formation of β- instead of α-polymorph in the product of TCP upon firing.

  1. Insitu synthesis of self-assembled gold nanoparticles on glass or silicon substrates through reactive inkjet printing

    KAUST Repository

    Abulikemu, Mutalifu


    A facile and low cost method for the synthesis of self-assembled nanoparticles (NPs) with minimal size variation and chemical waste by using reactive inkjet printing was developed. Gold NPs with diameters as small as (8±2)nm can be made at low temperature (120 °C). The size of the resulting NPs can be readily controlled through the concentration of the gold precursor and oleylamine ink. The pure gold composition of the synthesized NPs was confirmed by energy-dispersive X-ray spectroscopy (EDXS) analysis. High-resolution SEM (HRSEM) and TEM (HRTEM), and X-ray diffraction revealed their size and face-centered cubic (fcc) crystal structure, respectively. Owing to the high density of the NP film, UV/Vis spectroscopy showed a red shift in the intrinsic plasmonic resonance peak. We envision the extension of this approach to the synthesis of other nanomaterials and the production of tailored functional nanomaterials and devices. Midas touch: The use of low-cost manufacturing approaches in the synthesis of nanoparticles is critical for many applications. Reactive inkjet printing, along with a judicious choice of precursor/solvent system, was used to synthesize a relatively uniform assembly of crystalline gold nanoparticles, with diameters as small as (8±2)nm, over a given substrate surface. © 2014 WILEY-VCH Verlag GmbH.

  2. The relationship between fractional flow reserve, platelet reactivity and platelet leukocyte complexes in stable coronary artery disease.

    Directory of Open Access Journals (Sweden)

    Jan-Willem E M Sels

    Full Text Available BACKGROUND: The presence of stenoses that significantly impair blood flow and cause myocardial ischemia negatively affects prognosis of patients with stable coronary artery disease. Altered platelet reactivity has been associated with impaired prognosis of stable coronary artery disease. Platelets are activated and form complexes with leukocytes in response to microshear gradients caused by friction forces on the arterial wall or flow separation. We hypothesized that the presence of significantly flow-limiting stenoses is associated with altered platelet reactivity and formation of platelet-leukocyte complexes. METHODS: One hundred patients with stable angina were studied. Hemodynamic significance of all coronary stenoses was assessed with Fractional Flow Reserve (FFR. Patients were classified FFR-positive (at least one lesion with FFR≤0.75 or FFR-negative (all lesions FFR>0.80. Whole blood samples were stimulated with increasing concentrations of ADP, TRAP, CRP and Iloprost with substimulatory ADP. Expression of P-selectin as platelet activation marker and platelet-leukocyte complexes were measured by flowcytometry. Patients were stratified on clopidogrel use. FFR positive and negative patient groups were compared on platelet reactivity and platelet-leukocyte complexes. RESULTS: Platelet reactivity between FFR-positive patients and FFR-negative patients did not differ. A significantly lower percentage of circulating platelet-neutrophil complexes in FFR-positive patients and a similar non-significant decrease in percentage of circulating platelet-monocyte complexes in FFR-positive patients was observed. CONCLUSION: The presence of hemodynamically significant coronary stenoses does not alter platelet reactivity but is associated with reduced platelet-neutrophil complexes in peripheral blood of patients with stable coronary artery disease.

  3. Synthesis and optical properties of complex nanometal composite films (United States)

    Sandrock, Marie Louise

    We have successfully prepared gold pair particles of various size, shape, and inter-particle spacing using a template synthesis method involving anodic aluminum oxide films as host templates. Both transmission electron microscopy and polarized linear spectroscopy were used to evaluate the sample quality. The nature of the synthesis is such that the rotational axes of the rod-like structures are oriented normal to the host film surface. This characteristic leads to plasmon resonance spectra with dichroic behavior. In general, we found that both the plasmon resonance maxima and intensity are dependent on the size, shape, orientation, and inter-particle spacing of the pair particle nanostructures. We have successfully prepared more complex pair particle structures, including both rod and rod-sphere pairs. Linear polarization spectroscopy indicates that the plasmon resonance maxima are sensitive to both pair-particle geometry and inter-particle spacing. Possible evidence for interaction between the two members of the rod-sphere structure is seen in the experimental spectra. Quasi-static limit models also only qualitatively describe the polarization spectra of the rod-containing systems. We have succeeded in discerning the processes that cause the second harmonic generation of light (SHG) in nanoparticle composite systems. Second harmonic generation (SHG) studies using an incident wavelength of 780 nm indicate that SHG intensities under s-polarization are low and independent of incidence angle (theta) for composites containing centrosymmetric and non-centrosymmetric gold nanostructures. However, in p-polarization, both composites show an increase in SHG counts with theta, with the non-centrosymmetric structures showing a higher SHG signal than their centrosymmetric counterparts. These results are consistent with local-field enhancements arising from long particle axis dipolar plasmon resonances. Thus, we determined that symmetry does indeed play a large role in small

  4. Dithiafulvenyl-substituted phenylacetylene derivatives: synthesis and structure-property-reactivity relationships. (United States)

    Wang, Yunfei; Zhao, Yuming


    A series of regioisomers for dithiafulvenyl-substituted phenylacetylene derivatives was synthesized and characterized to show structure-dependent electronic properties and different reactivities in their oxidized states.

  5. A New Domain of Reactivity for High-Valent Dinuclear [M(μ-O)2 M'] Complexes in Oxidation Reactions. (United States)

    Engelmann, Xenia; Yao, Shenglai; Farquhar, Erik R; Szilvási, Tibor; Kuhlmann, Uwe; Hildebrandt, Peter; Driess, Matthias; Ray, Kallol


    The strikingly different reactivity of a series of homo- and heterodinuclear [(M(III) )(μ-O)2 (M(III) )'](2+) (M=Ni; M'=Fe, Co, Ni and M=M'=Co) complexes with β-diketiminate ligands in electrophilic and nucleophilic oxidation reactions is reported, and can be correlated to the spectroscopic features of the [(M(III) )(μ-O)2 (M(III) )'](2+) core. In particular, the unprecedented nucleophilic reactivity of the symmetric [Ni(III) (μ-O)2 Ni(III) ](2+) complex and the decay of the asymmetric [Ni(III) (μ-O)2 Co(III) ](2+) core through aromatic hydroxylation reactions represent a new domain for high-valent bis(μ-oxido)dimetal reactivity.

  6. Synthesis of Iron-Nitride Phases by Reactive Sputtering: Magnetic and Moessbauer Characterization. (United States)

    Lo, Cary Chia-Chiung

    This dissertation is concerned with the synthesis of discrete Fe-N phases by the reactive rf-sputtering technique, and their characterization by x-ray diffraction, Mossbauer spectroscopy, magnetic susceptibility and magnetization measurements, and SEM (scanning electron microscopy) to elucidate the growth, the structure, and the magnetic properties of the Fe-N system. Since discrete Fe-N phases are difficult to synthesize by conventional chemical methods as was tried by several researchers, resource was taken to prepare these phases by rf-sputtering, which is a relatively new and attractive technique. Single Fe-N phases (e.g., Fe(,4)N, Fe(,3)N, Fe(,2)N, etc.) were obtained by a careful control of various sputtering conditions, such as the total gas pressure (Ar + N(,2)), partial pressure of N(,2) (p(,N(,2))), substrate temperature, and the applied power. A detailed Mossbauer study of the Fe-N system was carried out as a function of temperature. The low -temperature (300-80 K) spectra of Fe(,3)N and Fe(,4)N showed a superparamagnetic behavior. The blocking temperature (T(,B)) for Fe(,4)N was found to be (TURN)80 K, whereas the T(,B) for Fe(,3)N appeared to be well below 80 K. The high-temperature (300-553 K) spectra were recorded in order to investigate the chemical stability of the nitride films and obtain the temperature at which the magnetic ordering disappeared. It was found that the Curie temperatures of Fe(,3)N and Fe(,4)N were lower than those of the bulk phases, arising from the canted spins at the surface of the film accompanied by thermal fluctuations. Furthermore, on the basis of the Mossbauer parameters, such as the isomer shift, quadrupole splitting and hyperfine field, as well as the magnetic moment per Fe atom, a coherent electronic structure for Fe(,4)N has been proposed. The microstructure of the Fe-N system was investigated by using SEM. These films showed a micro-columnar structure with the columns perpendicular to the plane of the film in most

  7. Synthesis of SiC/Ag/Cellulose Nanocomposite and Its Antibacterial Activity by Reactive Oxygen Species Generation

    Directory of Open Access Journals (Sweden)

    Andrzej Borkowski


    Full Text Available We describe the synthesis of nanocomposites, based on nanofibers of silicon carbide, silver nanoparticles, and cellulose. Silver nanoparticle synthesis was achieved with chemical reduction using hydrazine by adding two different surfactants to obtain a nanocomposite with silver nanoparticles of different diameters. Determination of antibacterial activity was based on respiration tests. Enzymatic analysis indicates oxidative stress, and viability testing was conducted using an epifluorescence microscope. Strong bactericidal activity of nanocomposites was found against bacteria Escherichia coli and Bacillus cereus, which were used in the study as typical Gram-negative and Gram-positive bacteria, respectively. It is assumed that reactive oxygen species generation was responsible for the observed antibacterial effect of the investigated materials. Due to the properties of silicon carbide nanofiber, the obtained nanocomposite may have potential use in technology related to water and air purification. Cellulose addition prevented silver nanoparticle release and probably enhanced bacterial adsorption onto aggregates of the nanocomposite material.

  8. Synthesis, characterisation, and oxygen atom transfer reactions involving the first gold(I)-alkylperoxo complexes. (United States)

    Collado, Alba; Gómez-Suárez, Adrián; Oonishi, Yoshihiro; Slawin, Alexandra M Z; Nolan, Steven P


    The synthesis of a new class of organogold species containing a peroxo moiety is reported. Complexes [Au(IPr)(OO(t)Bu)] and [Au(SIPr)(OO(t)Bu)] have been synthesised via a straightforward methodology using the parent gold(I) hydroxide complexes as synthons. These complexes have been successfully used in oxygen-transfer reactions to triphenylphosphine.

  9. [Response of bacillus sp. F26 to different reactive oxygen species stress characterized by antioxidative enzymes synthesis]. (United States)

    Yan, Guoliang; Hua, Zhaozhe; Du, Guocheng; Chen, Jian


    The oxidative response of Bacillus sp F26 to different forms of reactive oxygen species (ROS) stress including H2O2, O2- * and OH * were investigated by using diverse generating source of ROS, which were characterized by synthesis of antioxidative enzymes. It was shown that the responses of cells to oxidative stress are largely dependent on species, mode (instantaneous and continual) and intensity of stress. Higher synthesis rate of catalase (CAT) is crucial for Bacillus sp F26 to resist H2O2 stress. The damage of H2O2 to cell was minor if CAT can efficiently decompose H2O2 entering into cell, furthermore, the response can stimulate cell growths and sugar consumption. Conversely, cell growth and synthesis of antioxidative enzymes are greatly inhibited when the intensity of H2O2 stress overwhelms the cell capability of clearing H2O2. Due to the difference in mode and effect on cells between O2- * and H2O2, higher synthesis rates of CAT and superoxide dismutase (SOD) couldn't guarantee cells to eliminate H2O2 and O2- * efficiently. Therefore, the toxicity to cells induced by intracellular O2- * is more severe than H2O2 stress. Unlike response to H2O2 and O2- *, OH stress significantly inhibited cell growth and synthesis of antioxidative enzymes due to the fact OH * is most active ROS. Our results indicated that Bacillus sp F26 will show diverse biological behaviour in response to H2O2, O2- * and OH * of stress due to the discrepancy in chemical property. In order to survive in oxidative stress, cells will timely adjust their metabolism to adapt to new environment including regulating synthesis level of antioxidative enzymes, changing rates of cells growth and substrate consumption.

  10. Chemoenzymatic synthesis of hydrophobic glycoprotein: synthesis of saposin C carrying complex-type carbohydrate. (United States)

    Hojo, Hironobu; Tanaka, Hiromasa; Hagiwara, Masashi; Asahina, Yuya; Ueki, Akiharu; Katayama, Hidekazu; Nakahara, Yuko; Yoneshige, Azusa; Matsuda, Junko; Ito, Yukishige; Nakahara, Yoshiaki


    The complex-type N-linked octasaccharide oxazoline having LacNAc as the nonreducing end sugar was efficiently synthesized using the benzyl-protected LacNAc, mannose, and β-mannosyl GlcNAc units as key building blocks. To achieve a highly β-selective glycosylation with the LacNAc unit, the N-trichloroacetyl group was used for the protection of the amino group in the LacNAc unit. After complete assembly of these units and deprotection, the obtained free sugar was successfully derivatized into the corresponding sugar oxazoline. On the other hand, the N-acetylglucosaminylated saposin C, a hydrophobic lipid-binding protein, was chemically synthesized by the native chemical ligation reaction. On the basis of the previous results related to the synthesis of the nonglycosylated saposin C, the O-acyl isopeptide structure was introduced to the N-terminal peptide thioester carrying GlcNAc to improve its solubility toward aqueous organic solvents. The ligation reaction efficiently proceeded with the simultaneous O- to N-acyl shift at the O-acyl isopeptide moiety. After the removal of the cysteine-protecting group and folding, saposin C carrying GlcNAc was successfully obtained. The synthetic sugar oxazoline was then transferred to this glycoprotein using the mutant of endo-β-N-acetylglucosaminidase from Mucor hiemalis (Endo-M) (glycosynthase), and the saposin C carrying the complex-type nonasaccharide was successfully obtained.

  11. Effect of C6-olefin isomers on π-complexation for purification of 1-hexene by reactive extractive distillation

    NARCIS (Netherlands)

    Wentink, A.E.; Kockmann, D.; Kuipers, N.J.M.; Haan, de A.B.; Scholz, J.; Mulder, H.


    Separation of α-olefins from other olefin isomers is a difficult and expensive operation because of the low selectivities encountered. A promising alternative is π-complexation in combination with extractive distillation: reactive extractive distillation (RED). In this paper, silver nitrate dissolve

  12. Metal complexes with oxygen-functionalized NHC ligands: synthesis and applications. (United States)

    Hameury, Sophie; de Frémont, Pierre; Braunstein, Pierre


    Ligand design has met with considerable success with both categories of hybrid ligands, which are characterized by chemically different donor groups, and of N-heterocyclic carbenes (NHCs). Their spectacular development and diversity are attracting worldwide interest and offers almost unlimited diversity and potential in e.g. coordination/organometallic main group and transition metal chemistry, catalysis, medicinal chemistry and materials science. This review aims at providing a comprehensive update on a specific class of ligands that has enjoyed much attention in the past few years, at the intersection between the two categories mentioned above, that of hybrid NHC ligands in which the functionality associated with the carbene donor is of the oxygen-donor type. For each type of oxygen-donor present in such chelating (Section 1) or bridging (Section 2) hybrid ligands, we will examine the synthesis, structures and reactivity of their metal complexes and their applications, with a special focus on homogeneous catalysis (Section 3). Thus, hydrogenation, C-H bond activation, C-C, C-N, C-O bond formation, hydrolysis of silanes, oligomerization, polymerization, metathesis, hydrosilylation, C-C bond cleavage, acceptorless dehydrogenation, dehalogenation/hydrogen transfer, oxidation and reduction reactions will be successively presented in a tabular manner, to facilitate an overview and a rapid identification of the relevant publications describing which metals associated with a given oxygen functionality are most suitable. The literature coverage includes the year 2015.

  13. Students' conceptual performance on synthesis physics problems with varying mathematical complexity (United States)

    Ibrahim, Bashirah; Ding, Lin; Heckler, Andrew F.; White, Daniel R.; Badeau, Ryan


    A body of research on physics problem solving has focused on single-concept problems. In this study we use "synthesis problems" that involve multiple concepts typically taught in different chapters. We use two types of synthesis problems, sequential and simultaneous synthesis tasks. Sequential problems require a consecutive application of fundamental principles, and simultaneous problems require a concurrent application of pertinent concepts. We explore students' conceptual performance when they solve quantitative synthesis problems with varying mathematical complexity. Conceptual performance refers to the identification, follow-up, and correct application of the pertinent concepts. Mathematical complexity is determined by the type and the number of equations to be manipulated concurrently due to the number of unknowns in each equation. Data were collected from written tasks and individual interviews administered to physics major students (N =179 ) enrolled in a second year mechanics course. The results indicate that mathematical complexity does not impact students' conceptual performance on the sequential tasks. In contrast, for the simultaneous problems, mathematical complexity negatively influences the students' conceptual performance. This difference may be explained by the students' familiarity with and confidence in particular concepts coupled with cognitive load associated with manipulating complex quantitative equations. Another explanation pertains to the type of synthesis problems, either sequential or simultaneous task. The students split the situation presented in the sequential synthesis tasks into segments but treated the situation in the simultaneous synthesis tasks as a single event.

  14. The diastereoselective synthesis of octahedral cationic iridium hydride complexes with a stereogenic metal centre. (United States)

    Humbert, Nicolas; Mazet, Clément


    We report herein the highly diastereoselective synthesis of octahedral cationic Ir(iii) hydride complexes with a stereogenic metal centre following various strategies. The configurational stability of these compounds has also been investigated.

  15. Interplay among nitric oxide and reactive oxygen species: a complex network determining cell survival or death. (United States)

    Zhao, Jian


    Programmed cell death (PCD) is an integrated cellular process occurring in plant growth, development, and defense responses to facilitate normal growth and development and better survival against various stresses as a whole. As universal toxic chemicals in plant and animal cells, reactive oxygen or nitrogen species (ROS or RNS), mainly superoxide anion (O(2) (-*)), hydrogen peroxide (H(2)O(2)) or nitric oxide ((*)NO), have been studied extensively for their roles in PCD induction. Physiological and genetic studies have convincingly shown their essential roles. However, the details and mechanisms by which ROS and (*)NO interplay and induce PCD are not well understood. Our recent study on Cupressus lusitanica culture cell death revealed the elicitor-induced co-accumulation of ROS and (*)NO and interactions between (*)NO and H(2)O(2) or O(2)-(*) in different ways to regulate cell death. (*)NO and H(2)O(2) reciprocally enhanced the production of each other whereas (*)NO and O(2) (-*) showed reciprocal suppression on each other's production. It was the interaction between (*)NO and O(2)-(*) but not between (*)NO and H(2)O(2) that induced PCD, probably through peroxynitrite (ONOO(-)). In this addendum, some unsolved issues in the study were discussed based on recent studies on the complex network of ROS and (*)NO leading to PCD in animals and plants.

  16. Reactivation of immobilized acetylcholinesterase-tabun complex by pralidoxime, its isomers, and homologs. (United States)

    Hoskovcová, Monika; Halámek, Emil; Kobliha, Zbynek; Tusarová, Ivana


    Reactivation efficacy of three homologous and three isomeric series of pralidoxime-type reactivators with aldoxime group in position 2, 3 and 4 of the heterocycle was tested in reactivation of tabun-inhibited AChE. The experiments were performed with immobilized and stabilized porcine brain AChE. The enzyme activity was measured by Ellman method. Reactivation efficacy was determined by measurement of indicator fabric coloration intensity as a measure of AChE activity. Of the studied group of nine reactivators, isomers with the functional group in position 2 were the most effective. The highest value (30 %) for reactivation of inhibited AChE was found for 2PAE after treatment for 15 min at concentration 0.5 mg/cm(3). The efficacy of the isomers decreased in the order ortho > para > meta. No marked effect on the efficacy of the reactivators was observed on prolongation of the reactivation time. The reactivators efficacy decreased with decreasing concentration of their solutions.

  17. Ferrocenes as potential chemotherapeutic drugs: synthesis, cytotoxic activity, reactive oxygen species production and micronucleus assay. (United States)

    Pérez, Wanda I; Soto, Yarelys; Ortíz, Carmen; Matta, Jaime; Meléndez, Enrique


    Three new ferrocene complexes were synthesized with 4-(1H-pyrrol-1-yl)phenol group appended to one of the Cp ring. These are: 1,1'-4-(1H-pyrrol-1-yl)phenyl ferrocenedicarboxylate, ('Fc-(CO2-Ph-4-Py)2'), 1,4-(1H-pyrrol-1-yl)phenyl, 1'-carboxyl ferrocenecarboxylate ('Fc-(CO2-Ph-4-Py)CO2H') and 4-(1H-pyrrol-1-yl)phenyl ferroceneacetylate ('Fc-CH2CO2-Ph-4-Py'). The new species were characterized by standard analytical methods. Cyclic voltammetry experiments showed that Fc-CH2CO2-Ph-4-Py has redox potential very similar to the Fc/Fc(+) redox couple whereas Fc-(CO2-Ph-4-Py)2 and Fc-(CO2-Ph-4-Py)CO2H have redox potentials of over 400 mV higher than Fc/Fc(+) redox couple. The in vitro studies on Fc-(CO2-Ph-4-Py)2 and Fc-(CO2-Ph-4-Py)CO2H revealed that these two compounds have moderate anti-proliferative activity on MCF-7 breast cancer cell line. In contrast Fc-CH2CO2-Ph-4-Py which displayed low anti-proliferative activity. In the HT-29 colon cancer cell line, the new species showed low anti-proliferative activity. Cytokinesis-block micronucleus assay (CBMN) was performed on these ferrocenes and it was determined they induce micronucleus formation on binucleated cells and moderate genotoxic effects on the MCF-7 breast cancer cell line. There is a correlation between the IC50 values of the ferrocenes and the amount of micronucleus formation activity on binucleated cells and the reactive oxygen species (ROS) production on MCF-7 cell line.


    Institute of Scientific and Technical Information of China (English)

    QIU Yongxing; YU Xiaojie; FENG Lingxian


    A new reactive graft copolymer, poly (dimethyl siloxane)-graft-ω-hydroxyl-poly (ethylene oxide) (PDMS-g-(PEO-OH)), was synthesized by the hydrosilylation reaction of α, ω-bifunctional PEO macromonomer (CH2=CH-CH2-PEO-OH) with poly (hydromethylsiloxane) (PHMS). The obtained copolymer, exhibited the expected comblike structure as indicated by the result of detailed characterization and the needed reactivity as demonstrated by the result of esterification between PDMS-g-(PEO-OH)and aminoacetic acid. This reactive graft copolymer is expected to be very useful in the preparation of new bioactive polymer materials.

  19. Xanthohumol induces generation of reactive oxygen species and triggers apoptosis through inhibition of mitochondrial electron transfer chain complex I. (United States)

    Zhang, Bo; Chu, Wei; Wei, Peng; Liu, Ying; Wei, Taotao


    Xanthohumol is a prenylflavonoid extracted from hops (Humulus lupulus). It possesses anti-cancer and anti-inflammatory activities in vitro and in vivo, and offers therapeutic benefits for treatment of metabolic syndromes. However, the precise mechanisms underlying its pharmacological effects remain to be elucidated, together with its cellular target. Here, we provide evidence that xanthohumol directly interacts with the mitochondrial electron transfer chain complex I (NADH dehydrogenase), inhibits the oxidative phosphorylation, triggers the production of reactive oxygen species, and induces apoptosis. In addition, we show that as a result of the inhibition of the mitochondrial oxidative phosphorylation, xanthohumol exposure causes a rapid decrease of mitochondrial transmembrane potential. Furthermore, we showed that xanthohumol up-regulates the glycolytic capacity in cells, and thus compensates cellular ATP generation. Dissection of the multiple steps of aerobic respiration by extracellular flux assays revealed that xanthohumol specifically inhibits the activity of mitochondrial complex I, but had little effect on that of complex II, III and IV. Inhibition of complex I by xanthohumol caused the overproduction of reactive oxygen species, which are responsible for the induction of apoptosis in cancer cells. We also found that isoxanthohumol, the structural isomer of xanthohumol, is inactive to cells, suggesting that the reactive 2-hydroxyl group of xanthohumol is crucial for its targeting to the mitochondrial complex I. Together, the remodeling of cell metabolism revealed here has therapeutic potential for the use of xanthohumol.

  20. mu-opioid receptor-stimulated synthesis of reactive oxygen species is mediated via phospholipase D2. (United States)

    Koch, Thomas; Seifert, Anja; Wu, Dai-Fei; Rankovic, Marija; Kraus, Jürgen; Börner, Christine; Brandenburg, Lars-Ove; Schröder, Helmut; Höllt, Volker


    We have recently shown that the activation of the rat mu-opioid receptor (MOPr, also termed MOR1) by the mu-agonist [D-Ala(2), Me Phe(4), Glyol(5)]enkephalin (DAMGO) leads to an increase in phospholipase D2 (PLD2) activity and an induction of receptor endocytosis, whereas the agonist morphine which does not induce opioid receptor endocytosis fails to activate PLD2. We report here that MOPr-mediated activation of PLD2 stimulates production of reactive oxygen molecules via NADH/NADPH oxidase. Oxidative stress was measured with the fluorescent probe dichlorodihydrofluorescein diacetate and the role of PLD2 was assessed by the PLD inhibitor D-erythro-sphingosine (sphinganine) and by PLD2-small interfering RNA transfection. To determine whether NADH/NADPH oxidase contributes to opioid-induced production of reactive oxygen species, mu-agonist-stimulated cells were pre-treated with the flavoprotein inhibitor, diphenylene iodonium, or the specific NADPH oxidase inhibitor, apocynin. Our results demonstrate that receptor-internalizing agonists (like DAMGO, beta-endorphin, methadone, piritramide, fentanyl, sufentanil, and etonitazene) strongly induce NADH/NADPH-mediated ROS synthesis via PLD-dependent signaling pathways, whereas agonists that do not induce MOPr endocytosis and PLD2 activation (like morphine, buprenorphine, hydromorphone, and oxycodone) failed to activate ROS synthesis in transfected human embryonic kidney 293 cells. These findings indicate that the agonist-selective PLD2 activation plays a key role in the regulation of NADH/NADPH-mediated ROS formation by opioids.

  1. Reactive oxygen plasma-enabled synthesis of nanostructured CdO: tailoring nanostructures through plasma-surface interactions

    Energy Technology Data Exchange (ETDEWEB)

    Cvelbar, Uros; Mozetic, Miran [Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Ostrikov, Kostya [CSIRO Materials Science and Engineering, PO Box 218, Lindfield NSW 2070 (Australia)], E-mail:, E-mail:


    Plasma-assisted synthesis of nanostructures is one of the most precise and effective approaches used in nanodevice fabrication. Here we report on the innovative approach of synthesizing nanostructured cadmium oxide films on Cd substrates using a reactive oxygen plasma-based process. Under certain conditions, the surface morphology features arrays of crystalline CdO nano/micropyramids. These nanostructures grow via unconventional plasma-assisted oxidation of a cadmium foil exposed to inductively coupled plasmas with a narrow range of process parameters. The growth of the CdO pyramidal nanostructures takes place in the solid-liquid-solid phase, with the rates determined by the interaction of plasma-produced oxygen atoms and ions with the surface. It is shown that the size of the pyramidal structures can be effectively controlled by the fluxes of oxygen atoms and ions impinging on the cadmium surface. The unique role of the reactive plasma environment in the controlled synthesis of CdO nanopyramidal structures is discussed as well.

  2. An experimental evaluation of the instrumented flux synthesis method for the real-time estimation of reactivity. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, J.C.; Henry, A.F.; Lanning, D.D.; Bernard, J.A.


    One method of determining the flux density is flux synthesis which approximates the flux in the core by linear combinations of precomputed shape functions. In traditional flux synthesis, the unknown mixing coefficients are determined using a weighted residual method of solving the diffusion equation. In the instrumented synthesis method, the mixing coefficients are determined using count rates from neutron detectors in the core. In this way the mixing coefficients are linked to conditions in the reactor. Using the synthesized flux, kinetics parameters, notably reactivity, can be calculated in real time. An experimental evaluation has been performed in the Massachusetts Institute of Technology Reactor, MITR-II. Detector measurements have been collected using fission chambers placed at the periphery of the core. The reactor was put into a number of various conditions, both static and transient, and data were collected using a digital acquisition system for later combination with shape functions. Transients included increasing power, decreasing power, and a reactor scram. The shape functions were generated using Version 3.0 of the QUARTZ code, a quadratic nodal diffusion theory code in triangular-Z geometry. Supernodal analysis algorithms have been added to the original program, along with subroutines to guarantee diagonal dominance of the leakage matrix in the finite difference or quadratic current approximations in the coarse mesh. The agreement between coarse mesh and fine mesh in all cases is excellent, with finite difference coarse mesh solutions generally slightly better. The synthesis method has been shown to accurately reflect the changes from an initial condition by combining representative flux shapes. It can be concluded that, with proper calibration of the measurement system and inclusion of representative flux shapes, the instrumented synthesis method will properly predict the flux in the core under a number of conditions.

  3. Effects of protein synthesis inhibitors during reactivation of associative memory in the common snail induces reversible and irreversible amnesia. (United States)

    Solntseva, S V; Nikitin, V P; Kozyrev, S A; Shevelkin, A V; Lagutin, A V; Sherstnev, V V


    The effects of protein synthesis inhibitors on the reactivation of an associative skill consisting of refusing a particular food by common snails were studied. Animals were given single injections of a protein synthesis inhibitor (cycloheximide at 0.6 mg/snail or anisomycin at 0.4 mg) 24 h after three days of training, and were then presented with a "reminding" stimulus (the "conditioned reflex" food-banana) and tested for retention of the skill. Observations revealed an impairment of reproduction of the acquired skill 2.5 h after the "reminder," with spontaneous restoration at 4.5-5.5 h. Other snails were given single 1.8-mg doses of cycloheximide or three 0.6-mg doses with intervals of 2 h. "Reminders" were presented after each injection. In these conditions, impairment of reproduction of the conditioned reflex also appeared 2.5 h after the first "reminder," though amnesia lasted at least 30 days and repeat training of the animals produced only partial recovery of the skill. Thus, we have provided the first demonstration that recovery of a long-term memory "trace" on exposure to relatively low doses of protein synthesis inhibitors produces transient and short-lived amnesia, lasting 2-3 h, while long-term, irreversible amnesia occurs after longer-lasting or more profound suppression of protein synthesis. These results suggest that the "reminding" process induces reconsolidation of the " initial" memory, suppression of which by protein synthesis inhibitors leads to "erasure" of the memory "trace" and impairs consolidation on repeat training.

  4. Design, synthesis, and characterization of novel, nonquaternary reactivators of GF-inhibited human acetylcholinesterase. (United States)

    McHardy, Stanton F; Bohmann, Jonathan A; Corbett, Michael R; Campos, Bismarck; Tidwell, Michael W; Thompson, Paul Marty; Bemben, Chris J; Menchaca, Tony A; Reeves, Tony E; Cantrell, William R; Bauta, William E; Lopez, Ambrosio; Maxwell, Donald M; Brecht, Karen M; Sweeney, Richard E; McDonough, John


    The goal of this research was to identify structurally novel, non-quaternarypyridinium reactivators of GF (cyclosarin)-inhibited hAChE that possess the capacity to mediate in vitro reactivation of GF-inhibited human acetylcholinesterase (hAChE). New compounds were designed, synthesized and assessed in GF-inhibited hAChE assays. Structure activity relationships for AChE binding and reactivation of GF-inhibited hAChE were developed. Lead compounds from two different chemical series, represented by compounds 17 and 38, displayed proficient in vitro reactivation of GF-inhibited hAChE, while also possessing low inhibition of native enzyme. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Radiation-induced synthesis of vinyl copolymer based nanocomposites filled with reactive organic montmorillonite clay (United States)

    Kim, Sang-Kyum; Kwen, Hai-Doo; Choi, Seong-Ho


    Vinyl copolymer-clay nanocomposites were prepared by γ-irradiation-initiated radical polymerization using a mixture of styrene (St) and divinyl benzene (DVB) in the presence of reactive organic montmorillonite clay (OMMT) in methanol at room temperature. Reactive OMMT was synthesized by a cation exchange reaction of Na+-MMT and 1-[(4-ethylphenyl)methyl]-3-butyl-imidazolium chloride as a reactive organic modifier in an aqueous solution. The microstructures of the nanocomposites were confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The thermal stability was examined by thermo gravimetric analysis (TGA). As a result, the reactive OMMT was a good additive material for preparing vinyl copolymer-clay nanocomposites.

  6. Combining Amine-Reactive Cross-Linkers and Photo-Reactive Amino Acids for 3D-Structure Analysis of Proteins and Protein Complexes. (United States)

    Lössl, Philip; Sinz, Andrea


    During the last 15 years, the combination of chemical cross-linking and high-resolution mass spectrometry (MS) has matured into an alternative approach for analyzing 3D-structures of proteins and protein complexes. Using the distance constraints imposed by the cross-links, models of the protein or protein complex under investigation can be created. The majority of cross-linking studies are currently conducted with homobifunctional amine-reactive cross-linkers. We extend this "traditional" cross-linking/MS strategy by adding complementary photo-cross-linking data. For this, the diazirine-containing unnatural amino acids photo-leucine and photo-methionine are incorporated into the proteins and cross-link formation is induced by UV-A irradiation. The advantage of the photo-cross-linking strategy is that it is not restricted to lysine residues and that hydrophobic regions in proteins can be targeted, which is advantageous for investigating membrane proteins. We consider the strategy of combining cross-linkers with orthogonal reactivities and distances to be ideally suited for maximizing the amount of structural information that can be gained from a cross-linking experiment.

  7. Reactivity of mononuclear alkylperoxo copper(II) complex. O-O bond cleavage and C-H bond activation. (United States)

    Kunishita, Atsushi; Ishimaru, Hirohito; Nakashima, Satoru; Ogura, Takashi; Itoh, Shinobu


    A detailed reactivity study has been carried out for the first time on a new mononuclear alkylperoxo copper(II) complex, which is generated by the reaction of copper(II) complex supported by the bis(pyridylmethyl)amine tridentate ligand containing a phenyl group at the 6-position of the pyridine donor groups and cumene hydroperoxide (CmOOH) in CH3CN. The cumylperoxo copper(II) complex thus obtained has been found to undergo homolytic cleavage of the O-O bond and induce C-H bond activation of exogenous substrates, providing important insights into the catalytic mechanism of copper monooxygenases.

  8. Flaviviral Replication Complex: Coordination between RNA Synthesis and 5'-RNA Capping. (United States)

    Klema, Valerie J; Padmanabhan, Radhakrishnan; Choi, Kyung H


    Genome replication in flavivirus requires (-) strand RNA synthesis, (+) strand RNA synthesis, and 51-RNA capping and methylation. To carry out viral genome replication, flavivirus assembles a replication complex, consisting of both viral and host proteins, on the cytoplasmic side of the endoplasmic reticulum (ER) membrane. Two major components of the replication complex are the viral non-structural (NS) proteins NS3 and NS5. Together they possess all the enzymatic activities required for genome replication, yet how these activities are coordinated during genome replication is not clear. We provide an overview of the flaviviral genome replication process, the membrane-bound replication complex, and recent crystal structures of full-length NS5. We propose a model of how NS3 and NS5 coordinate their activities in the individual steps of (-) RNA synthesis, (+) RNA synthesis, and 51-RNA capping and methylation.

  9. Coupling of Carbon Dioxide with Epoxides Efficiently Catalyzed by Thioether-Triphenolate Bimetallic Iron(III) Complexes: Catalyst Structure-Reactivity Relationship and Mechanistic DFT Study

    KAUST Repository

    Della Monica, Francesco


    A series of dinuclear iron(III)I complexes supported by thioether-triphenolate ligands have been prepared to attain highly Lewis acidic catalysts. In combination with tetrabutylammonium bromide (TBAB) they are highly active catalysts in the synthesis of cyclic organic carbonates through the coupling of carbon dioxide to epoxides with the highest initial turnover frequencies reported to date for the conversion of propylene oxide to propylene carbonate for iron-based catalysts (5200h-1; 120°C, 2MPa, 1h). In particular, these complexes are shown to be highly selective catalysts for the coupling of carbon dioxide to internal oxiranes affording the corresponding cyclic carbonates in good yield and with retention of the initial stereochemical configuration. A density functional theory (DFT) investigation provides a rational for the relative high activity found for these Fe(III) complexes, showing the fundamental role of the hemilabile sulfur atom in the ligand skeleton to promote reactivity. Notably, in spite of the dinuclear nature of the catalyst precursor only one metal center is involved in the catalytic cycle. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Acrolein stimulates the synthesis of IL-6 and C-reactive protein (CRP) in thrombosis model mice and cultured cells. (United States)

    Saiki, Ryotaro; Hayashi, Daisuke; Ikuo, Yukiko; Nishimura, Kazuhiro; Ishii, Itsuko; Kobayashi, Kaoru; Chiba, Kan; Toida, Toshihiko; Kashiwagi, Keiko; Igarashi, Kazuei


    Measurements of protein-conjugated acrolein (PC-Acro), IL-6, and C-reactive protein (CRP) in plasma were useful for identifying silent brain infarction with high sensitivity and specificity. The aim of this study was to determine whether acrolein causes increased production of IL-6 and CRP in thrombosis model mice and cultured cells. In mice with photochemically induced thrombosis, acrolein produced at the locus of infarction increased the level of IL-6 and then CRP in plasma. This was confirmed in cell culture systems - acrolein stimulated the production of IL-6 in mouse neuroblastoma Neuro-2a cells, mouse macrophage-like J774.1 cells, and human umbilical vein endothelial cells (HUVEC), and IL-6 in turn stimulated the production of CRP in human hepatocarcinoma cells. The level of IL-6 mRNA was increased by acrolein through an increase in phosphorylation of the transcription factors, c-Jun, and NF-κB p65. Furthermore, CRP stimulated IL-6 production in mouse macrophage-like J774.1 cells and HUVEC. IL-6 functioned as a protective factor against acrolein toxicity in Neuro-2a cells and HUVEC. These results show that acrolein stimulates the synthesis of IL-6 and CRP, which function as protecting factors against acrolein toxicity, and that the combined measurement of PC-Acro, IL-6, and CRP is effective for identification of silent brain infarction. The combined measurements of protein-conjugated acrolein (PC-Acro), IL-6, and C-reactive protein (CRP) in plasma were useful for identifying silent brain infarction. The aim of this study was to determine whether acrolein causes increased production of IL-6 and CRP, and indeed acrolein increased IL-6 synthesis and IL-6 in turn increased CRP synthesis. Furthermore, IL-6 decreased acrolein toxicity in several cell lines.

  11. η6-Cycloparaphenylene transition metal complexes: synthesis, structure, photophysical properties, and application to the selective monofunctionalization of cycloparaphenylenes. (United States)

    Kubota, Natsumi; Segawa, Yasutomo; Itami, Kenichiro


    The synthesis, structure, photophysical properties, and reactivity of cycloparaphenylenes (CPPs) coordinated to group 6 transition metal fragments are described. The η(6)-coordination of [9]CPP or [12]CPP with M(CO)6 (M = Cr, Mo, W) afforded the corresponding [n]CPP-M(CO)3 complexes (n = 9, 12; M = Cr, Mo, W). In the (1)H NMR spectra of these complexes, characteristic upfield-shifted singlet signals corresponding to the four hydrogen atoms attached to the coordinated C6H4 ring of the CPPs were observed at 5.4-5.9 ppm. The complex [9]CPP-Cr(CO)3 could be successfully isolated in spite of its instability. X-ray crystallographic analysis and computational studies of [9]CPP-Cr(CO)3 revealed that chromium-CPP coordination occurs at the convex surface of [9]CPP both in the solid state and in solution. TD-DFT calculations suggested that the emerging high-wavenumber absorption peak upon coordination of [9]CPP to Cr(CO)3 should be assigned to a weak HOMO-LUMO transition. Moreover, by using the complex [9]CPP-Cr(CO)3, a rapid and highly monoselective CPP functionalization has been achieved. The established one-pot method, consisting of complexation, deprotonation, nucleophilic substitution, and decomplexation steps, yielded silyl-, boryl-, and methoxycarbonyl-substituted CPPs in up to 93% yield relative to reacted starting material.

  12. Synthetic Source Inversion Tests with the Full Complexity of Earthquake Source Processes, Including Both Supershear Rupture and Slip Reactivation (United States)

    Song, Seok Goo; Dalguer, Luis A.


    Recent studies in dynamic source modeling and kinematic source inversion show that earthquake rupture may contain greater complexity than we previously anticipated, including multiple slipping at a given point on a fault. Finite source inversion methods suffer from the nonuniqueness of solutions, and it may become more serious if we aim to resolve more complex rupture models. In this study, we perform synthetic inversion tests with dynamically generated complex rupture models, including both supershear rupture and slip reactivation, to understand the possibility of resolving complex rupture processes by inverting seismic waveform data. We adopt a linear source inversion method with multiple windows, allowing for slipping from the nucleation of rupture to the termination at all locations along a fault. We regularize the model space effectively in the Bayesian framework and perform multiple inversion tests by considering the effect of inaccurate Green's functions and station distributions. We also perform a spectral stability analysis. Our results show that it may be possible to resolve both a supershear rupture front and reactivated secondary slipping using the linear inversion method if those complex features are well separated from the main rupture and produce a fair amount of seismic energy. It may be desirable to assume the full complexity of an earthquake rupture when we first develop finite source models after a major event occurs and then assume a simple rupture model for stability if the estimated models do not show a clear pattern of complex rupture processes.

  13. Copper-peptide complex structure and reactivity when found in conserved His-X(aa)-His sequences. (United States)

    Park, Ga Young; Lee, Jung Yoon; Himes, Richard A; Thomas, Gnana S; Blackburn, Ninian J; Karlin, Kenneth D


    Oxygen-activating copper proteins may possess His-X(aa)-His chelating sequences at their active sites and additionally exhibit imidiazole group δN vs εN tautomeric preferences. As shown here, such variations strongly affect copper ion's coordination geometry, redox behavior, and oxidative reactivity. Copper(I) complexes bound to either δ-HGH or ε-HGH tripeptides were synthesized and characterized. Structural investigations using X-ray absorption spectroscopy, density functional theory calculations, and solution conductivity measurements reveal that δ-HGH forms the Cu(I) dimer complex [{Cu(I)(δ-HGH)}2](2+) (1) while ε-HGH binds Cu(I) to give the monomeric complex [Cu(I)(ε-HGH)](+) (2). Only 2 exhibits any reactivity, forming a strong CO adduct, [Cu(I)(ε-HGH)(CO)](+), with properties closely matching those of the copper monooxygenase PHM. Also, 2 is reactive toward O2 or H2O2, giving a new type of O2-adduct or Cu(II)-OOH complex, respectively.

  14. Synthesis and in vitro reactivation study of isonicotinamide derivatives of 2-(hydroxyimino)-N-(pyridin-3-yl)acetamide as reactivators of Sarin and VX inhibited human acetylcholinesterase (hAChE). (United States)

    Karade, Hitendra N; Raviraju, G; Acharya, B N; Valiveti, Aditya Kapil; Bhalerao, Uma; Acharya, Jyotiranjan


    Previously (Karade et al., 2014), we have reported the synthesis and in vitro evaluation of bis-pyridinium derivatives of pyridine-3-yl-(2-hydroxyimino acetamide), as reactivators of sarin and VX inhibited hAChE. Few of the molecules showed superior in vivo protection efficacy (mice model) (Kumar et al., 2014; Swami et al., 2016) in comparison to 2-PAM against DFP and sarin poisoning. Encouraged by these results, herein we report the synthesis and in vitro evaluation of isonicotinamide derivatives of pyridine-3-yl-(2-hydroxyimino acetamide) (4a-4d) against sarin and VX inhibited erythrocyte ghost hAChE. Reactivation kinetics of these compounds was studied and the determined kinetic parameters were compared with that of commercial reactivators viz. 2-PAM and obidoxime. In comparison to 2-PAM and obidoxime, oxime 4a and 4b exhibited enhanced reactivation efficacy toward sarin inhibited hAChE while oxime 4c showed far greater reactivation efficacy toward VX inhibited hAChE. The acid dissociation constant and IC50 values of these oximes were determined and correlated with the observed reactivation potential.

  15. Coupling a system code with computational fluid dynamics for the simulation of complex coolant reactivity effects

    Energy Technology Data Exchange (ETDEWEB)

    Bertolotto, D.


    The current doctoral research is focused on the development and validation of a coupled computational tool, to combine the advantages of computational fluid dynamics (CFD) in analyzing complex flow fields and of state-of-the-art system codes employed for nuclear power plant (NPP) simulations. Such a tool can considerably enhance the analysis of NPP transient behavior, e.g. in the case of pressurized water reactor (PWR) accident scenarios such as Main Steam Line Break (MSLB) and boron dilution, in which strong coolant flow asymmetries and multi-dimensional mixing effects strongly influence the reactivity of the reactor core, as described in Chap. 1. To start with, a literature review on code coupling is presented in Chap. 2, together with the corresponding ongoing projects in the international community. Special reference is made to the framework in which this research has been carried out, i.e. the Paul Scherrer Institute's (PSI) project STARS (Steady-state and Transient Analysis Research for the Swiss reactors). In particular, the codes chosen for the coupling, i.e. the CFD code ANSYS CFX V11.0 and the system code US-NRC TRACE V5.0, are part of the STARS codes system. Their main features are also described in Chap. 2. The development of the coupled tool, named CFX/TRACE from the names of the two constitutive codes, has proven to be a complex and broad-based task, and therefore constraints had to be put on the target requirements, while keeping in mind a certain modularity to allow future extensions to be made with minimal efforts. After careful consideration, the coupling was defined to be on-line, parallel and with non-overlapping domains connected by an interface, which was developed through the Parallel Virtual Machines (PVM) software, as described in Chap. 3. Moreover, two numerical coupling schemes were implemented and tested: a sequential explicit scheme and a sequential semi-implicit scheme. Finally, it was decided that the coupling would be single

  16. Radiometric ligand binding assay for C-reactive protein. Complexed C-reactive protein is not detectable in acute phase serum. (United States)

    De Beer, F C; Shine, B; Pepys, M B


    A radiometric ligand binding assay for human C-reactive protein (CRP) was established using pneumococcal C polysaccharide (CPS) coupled to magnetizable cellulose particles as the solid phase ligand. Competition for binding to the solid phase between 125I-CRP and unlabelled CRP permitted detection of 30 micrograms/l of CRP and the precise assay of concentrations up to 3000 micrograms/l. Identical results were obtained when the assay was used to quantitate isolated pure CRP and pure CRP added to normal human serum. However in vitro addition of known ligands for CRP to acute phase serum resulted in lowering of the apparent CRP concentration in this assay and addition of as little as 1 microgram/l of free CPS or 1 mg/l of lecithin was demonstrable in this way. A combination of the ligand binding assay and the standard electroimmunoassay for CRP was therefore used to test acute phase sera for the presence of CRP complexed in vitro. No evidence of complexed CRP was detected among sera containing between 1-319 mg/l of CRP from patients with Hodgkin's disease (10), rheumatoid arthritis (10), Crohn's disease (19) and various microbial infections (11), including six with subacute bacterial endocarditis. Since it is likely that CRP does form complexes with its ligands in the plasma these results suggest that complexed CRP is rapidly cleared from the circulation.

  17. Synthesis, spectroscopic characterization and electronic structure of some new Cu(I) carbene complexes

    Indian Academy of Sciences (India)

    Chinnappan Sivasankar; Christina Baskaran; Ashoka G Samuelson


    Reaction of oligomeric Cu(I) complexes [Cu{-S-C(=NR)(O-Ar-CH3)}] with Lewis acids gave Cu(I) carbene complexes, which were characterized by 1H and 13C NMR spectroscopy. Cu(I) carbene complexes could be directly generated from RNCS, Cu(I)-OAr and Lewis acids; this method can be used to prepare Cu(I) carbene complexes with different substitutents on the carbene carbon. The complexes were unreactive towards olefins and do not undergo cyclopropanation. Electronic structure calculations (DFT) show that the charge on the carbene carbon plays an important role in controlling the reactivity of the carbene complex.

  18. Aplicação de α-oxoceteno ditiocetais em síntese orgânica Reactivity of α-oxoketene dithiocetals in organic synthesis

    Directory of Open Access Journals (Sweden)

    Geonir M. Siqueira


    Full Text Available The synthesis and reactivity of α-oxoketenes dithioacetals (S,S-acetals, general structure [(R¹C=OC(R²=C(SR³(SR4], are reported. We also showed the application of S,S acetals as synthons for efficient synthesis of isoxazoles, pyrazoles, indazoles, thiophenes, dithiol thiones, pyridines, pyrimidines and other heterocycles. This work aims to review the importance of α-oxoketenes dithioacetals in organic chemistry during the past few years.

  19. Synthesis of cyclopentadienyl ruthenium complexes bearing pendant chelating picolinates through an electrophilic precursor


    Streu, Craig; Carroll, Patrick J.; Kohli, Rakesh K.; Meggers, Eric


    This note reports the facile synthesis of two ruthenium cyclopentadienyl half-sandwich complexes functionalized with coordinating α-picolinates. The synthetic approach involves the (η5-chloromethylcyclopentadienyl)(η6-benzene)ruthenium(II) cation as a useful common building block for cyclopentadienyl complexes bearing anchored ligands.

  20. Ruthenium(II) arene complexes with oligocationic triarylphosphine ligands: synthesis, DNA interactions and in vitro properties

    NARCIS (Netherlands)

    Snelders, D.J.M.; Casini, A.; Edafe, F.; van Koten, G.; Klein Gebbink, R.J.M.; Dyson, P.J.


    The synthesis, DNA binding properties and cytotoxicity of a series of Ru(II)-arene complexes containing oligocationic ammonium-functionalized triarylphosphines, of the type Ru(p-cymene)Cl2(L) (L ¼ oligocationic phosphine), are reported. The complexes are highly charged (the overall charge states bei

  1. Synthesis of sp3-rich scaffolds for molecular libraries through complexity-generating cascade reactions

    DEFF Research Database (Denmark)

    Flagstad, Thomas; Min, Geanna; Bonnet, K.


    An efficient strategy for the synthesis of complex small molecules from simple building blocks is presented. Key steps of the strategy include tandem Petasis and Diels–Alder reactions, and divergent complexity-generating cyclization cascades from a key dialdehyde intermediate. The methodology is ...

  2. Clusters containing carbene ligands. The unusual synthesis, coordination, and reactivity of a bridging (dimetalliomethyl)(diethylamino)carbene ligand in the cluster complex Os/sub 3/(CO)/sub 9/(/mu//sub 3/-HCC(NEt/sub 2/))(/mu/-H)/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Adams, R.D.; Tanner, J.T.


    The photoinduced decarbonylation of Os/sub 3/-(CO)/sub 10/(/mu/-C(H)C(H)NEt/sub 2/)(/mu/-H) (1) yields Os/sub 3/(CO)/sub 9/(/mu//sub 3/-CC(H)NEt/sub 2/)(/mu/-H)/sub 2/ (2; 58% yield) and Os/sub 3/(CO)/sub 9/(/mu//sub 3/-C(H)CNEt/sub 2/)(/mu/-H)/sub 2/ (3; 21% yield). Compound 3 was also obtained from 2 in 70% yield by heating to 68/degree/C in hexane solvent. Both products were characterized by IR, /sup 1/H NMR and X-ray diffraction analysis. Compound 2 contains and /eta//sup 1/-triply bridging (diethylamino)alkenylidene ligand coordinated to a triangular triosmium cluster. Compound 3 contains a triply bridging HC/sub 2/NEt/sub 2/ ligand that is formulated to include two osmiums as a (dimetalliomethyl)(diethylamino)carbene ligand on the basis of structural and reactivity evidence. Compound 3 reacts with NHPr/sub 2//sup n/ to yield Os/sub 3/(CO)/sub 9/(/mu//sub 3/-C(H)CNPr/sub 2//sup n/)(/mu/-H)/sub 2/ (4) in 74% yield by replacement of the diethylamino group.

  3. Solid-phase synthesis of complex and pharmacologically interesting heterocycles

    DEFF Research Database (Denmark)

    Nielsen, Thomas Eiland


    Efficient routes for the creation of heterocycles continue to be one of the primary goals for solid-phase synthesis. Recent advances in this field rely most notably on transition-metal-catalysis and N-acyliminium chemistry to mediate a range of cyclization processes for the generation of compounds...

  4. Solid-phase synthesis of complex and pharmacologically interesting heterocycles

    DEFF Research Database (Denmark)

    Nielsen, Thomas Eiland


    Efficient routes for the creation of heterocycles continue to be one of the primary goals for solid-phase synthesis. Recent advances in this field rely most notably on transition-metal-catalysis and N-acyliminium chemistry to mediate a range of cyclization processes for the generation of compounds...

  5. Self-organised synthesis of Rh nanostructures with tunable chemical reactivity

    Directory of Open Access Journals (Sweden)

    Lizzit S


    Full Text Available AbstractNonequilibrium periodic nanostructures such as nanoscale ripples, mounds and rhomboidal pyramids formed on Rh(110 are particularly interesting as candidate model systems with enhanced catalytic reactivity, since they are endowed with steep facets running along nonequilibrium low-symmetry directions, exposing a high density of undercoordinated atoms. In this review we report on the formation of these novel nanostructured surfaces, a kinetic process which can be controlled by changing parameters such as temperature, sputtering ion flux and energy. The role of surface morphology with respect to chemical reactivity is investigated by analysing the carbon monoxide dissociation probability on the different nanostructured surfaces.

  6. Survey on synthesis and reaction of environmentally benign water-soluble metal complex catalysts; Kankyo chowagata suiyosei sakutai shokubai no gosei hanno no chosa

    Energy Technology Data Exchange (ETDEWEB)



    This report describes the research trend survey results on the synthesis and reaction of water-soluble metal complexes which are regarded as environmentally benign catalysts. For the synthesis and catalysis of water-soluble complexes, synthetic methods of water-soluble phosphines, such as sulfonated TPPMS and TPPTS, are described in detail. Synthesis and reactivity of hydroxymethylphosphines are introduced, and the application of electrospray mass spectroscopy is elucidated as a tool for the analysis of them. Changes of the application of transition metal complexes with water-soluble phosphines to catalysis are described. Dual catalysts which have both functions of phase transfer catalysts and homogeneous catalysts are introduced. Concept of counter phase transfer catalysts is also introduced, and some catalytic reactions are described. In addition, this report introduces catalysis of water-soluble polymer-supported metal complexes, immobilization of metal colloids with water-soluble ligands and their analysis, and water-soluble complexes as hybrid catalysts. 144 refs., 94 figs., 10 tabs.

  7. Controlled synthesis of titania using water-soluble titanium complexes: A review (United States)

    Truong, Quang Duc; Dien, Luong Xuan; Vo, Dai-Viet N.; Le, Thanh Son


    The development of human society has led to the increase in energy and resources consumption as well as the arising problems of environmental damage and the toxicity to the human health. The development of novel synthesis method which tolerates utilization of toxic solvents and chemicals would fulfill the demand of the society for safer, softer, and environmental friendly technologies. For the past decades, a remarkable progress has been attained in the development of new water-soluble titanium complexes (WSTC) and their use for the synthesis of nanocrystalline titanium dioxide materials by aqueous solution-based approaches. The progress of synthesis of nanocrystalline titanium dioxide using such WSTCs is reviewed in this work. The key structural features responsible for the successfully controlled synthesis of TiO2 are discussed to provide guidelines for the morphology-controlled synthesis. Finally, this review ends with a summary and some perspectives on the challenges as well as new directions in this fascinating research.

  8. Synthesis of benzamides by microwave assisted ring opening of less reactive dimethylaminobenzylidene oxazolone

    Directory of Open Access Journals (Sweden)

    Saurabh C. Khadse


    Full Text Available This paper presents the synthesis of some benzamide compounds (B1–B10 by microwave-assisted ring opening of 4-(4-dimethylaminobenzylidene-2-phenyl-5-oxazolone (AZ4. By conventional synthesis involving heating, it was found difficult to obtain ring-opened products, probably due to poor tendency of the carbonyl carbon (C5 of AZ4 to undergo nucleophilic attack by mono/or disubstituted anilines. Microwave assisted reactions were easy to perform, have reduced the reaction time and produced good yields.

  9. Synthesis of oxidized guar gum by dry method and its application in reactive dye printing. (United States)

    Gong, Honghong; Liu, Mingzhu; Zhang, Bing; Cui, Dapeng; Gao, Chunmei; Ni, Boli; Chen, Jiucun


    The aim of this study was to prepare oxidized guar gum with a simple dry method, basing on guar gum, hydrogen peroxide and a small amount of solvent. To obtain a product with suitable viscosity for reactive dye printing, the effects of various factors such as the amount of oxidant and solvent, reaction temperature and time were studied with respect to the viscosity of reaction products. The product was characterized by Fourier transform infrared spectroscopy, size exclusion chromatography, scanning electron microscopy and differential scanning calorimetry. The hydrated rate of guar gum and oxidized guar gum was estimated through measuring the required time when their solutions (1%, w/v) reached the maximum viscosity. The effects of the salt concentration and pH on viscosity of the resultant product were studied. The mixed paste containing oxidized guar gum and carboxymethyl starch was prepared and its viscosity was determined by the viscometer. The rheological property of the mixed paste was appraised by the printing viscosity index. In addition, the applied effect of mixed paste in reactive dye printing was examined by assessing the fabric stiffness, color yield and sharp edge to the printed image in comparison with sodium alginate. And the results indicated that the mixed paste could partially replace sodium alginate as thickener in reactive dye printing. The study also showed that the method was low cost and eco-friendly and the product would have an extensive application in reactive dye printing.

  10. Synthesis of phosphorus-containing polyoxamacrocycles with one to two reactive thiophosphoryl chloride groups

    Institute of Scientific and Technical Information of China (English)

    Xiao Mei Zhang; Dao Quan Wang; Wan Yi Chen


    Novel phosphorus-containing polyoxamacrocycles with one to two reactive thiophosphoryl chloride groups 5, 6, 7, 8 weresynthesized from bishydroxyl compounds 1, 2, 3, 4 and thiophosphoryl chloride respectively. Their structures were confirmed by 1HNMR, 13C NMR, 31p NMR and elemental analysis.2008 Dan Quan Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  11. Design and Synthesis of Bifunctional Oxime Reactivators of OP- inhibited Cholinesterase (United States)


    military and civilian personnel. Reactivators of OP inhibited cholinesterases can serve as OP agent antidotes but can be limited by their poor...assisted bifunctional catalytic mechanism 46 O N O N OH 11 REPORTABLE OUTCOMES: None CONCLUSION: We have successfully evaluated the synthetic

  12. Synthesis and application of polyepoxide cardanol glycidyl ether as biobased polyepoxide reactive diluent for epoxy resin (United States)

    Polyepoxide cardanol glycidyl ether (PECGE), a novel cardanol derivative, was synthesized and used as reactive diluent for petroleum-based epoxy resin in this work. The synthetic condition was first optimized, and the resultant PECGE diluent was characterized using Fourier transform infrared spectro...

  13. Design, synthesis and evaluation of small molecule reactive oxygen species generators as selective Mycobacterium tuberculosis inhibitors. (United States)

    Dharmaraja, Allimuthu T; Alvala, Mallika; Sriram, Dharmarajan; Yogeeswari, Perumal; Chakrapani, Harinath


    Here, we report 5-hydroxy-1,2,3,4,4a,9a-hexahydro-1,4-ethano-9,10-anthraquinone (13), a small molecule generating reactive oxygen species (ROS) in pH 7.4 buffer under ambient aerobic conditions that has selective and potent Mycobacterium tuberculosis growth inhibitory activity.

  14. The complex interplay of iron metabolism, reactive oxygen species, and reactive nitrogen species: insights into the potential of various iron therapies to induce oxidative and nitrosative stress. (United States)

    Koskenkorva-Frank, Taija S; Weiss, Günter; Koppenol, Willem H; Burckhardt, Susanna


    Production of minute concentrations of superoxide (O2(*-)) and nitrogen monoxide (nitric oxide, NO*) plays important roles in several aspects of cellular signaling and metabolic regulation. However, in an inflammatory environment, the concentrations of these radicals can drastically increase and the antioxidant defenses may become overwhelmed. Thus, biological damage may occur owing to redox imbalance-a condition called oxidative and/or nitrosative stress. A complex interplay exists between iron metabolism, O2(*-), hydrogen peroxide (H2O2), and NO*. Iron is involved in both the formation and the scavenging of these species. Iron deficiency (anemia) (ID(A)) is associated with oxidative stress, but its role in the induction of nitrosative stress is largely unclear. Moreover, oral as well as intravenous (iv) iron preparations used for the treatment of ID(A) may also induce oxidative and/or nitrosative stress. Oral administration of ferrous salts may lead to high transferrin saturation levels and, thus, formation of non-transferrin-bound iron, a potentially toxic form of iron with a propensity to induce oxidative stress. One of the factors that determine the likelihood of oxidative and nitrosative stress induced upon administration of an iv iron complex is the amount of labile (or weakly-bound) iron present in the complex. Stable dextran-based iron complexes used for iv therapy, although they contain only negligible amounts of labile iron, can induce oxidative and/or nitrosative stress through so far unknown mechanisms. In this review, after summarizing the main features of iron metabolism and its complex interplay with O2(*-), H2O2, NO*, and other more reactive compounds derived from these species, the potential of various iron therapies to induce oxidative and nitrosative stress is discussed and possible underlying mechanisms are proposed. Understanding the mechanisms, by which various iron formulations may induce oxidative and nitrosative stress, will help us

  15. 'Reactive' nano-complex coated medical cotton: a facile avenue for tailored release of small molecules. (United States)

    Rather, Adil Majeed; Mahato, Sulendar; Maji, Kousik; Gogoi, Neeha; Manna, Uttam


    Controlled and sustained release of drug-like small molecules in an aqueous medium still remains a challenging problem due to rapid infiltration of liquid water in most reported drug release systems. However, internal-superhydrophobicity with an antifouling property extending beyond the surface of a material recently has been recognized as a potential avenue for sustained and extended release of drug-like small molecules. Sluggish removal of metastable trapped air in a superhyrophobic material provides a basis to achieve extended release of encapsulated small molecules. In this article, naturally abundant medical-cotton-extensively used in wound management including control of bleeding, absorbance of secretions and protecting wounds from contamination-is strategically exploited in tailoring (from rapid to extended) the release of small molecules by appropriate modulation of liquid water wettability. Modulation included bio-mimicked adhesive and non-adhesive superhydrophobicity of the medical cotton without erosion of any polymeric material. In this process, amine 'reactive' nano-complexes (RNC) were prepared by just mixing branched poly(ethylenimine) (BPEI) with dipentaerythritol pentaacrylate (5Acl) in ethanol with appropriate compositions. Then they were covalently immobilized on fibrous medical-cotton through a facile and robust 1,4-conjugated addition reaction. Residual acrylate moieties in the immobilized RNC provide an opportunity to tailor water wettability through strategic and appropriate post-chemical modification of RNC-coated medical cotton with a primary amine containing various small molecules. This medical-cotton with tunable wettability was exploited further to control the release rate of small molecules from rapid (100 days) times. A volatile solvent induced transient and reversible switching of anti-fouling properties which allowed further varying the amount of post-loading small molecules into the medical cotton up to 2.36 wt% without

  16. Chemical Imaging and Dynamical Studies of Reactivity and Emergent Behavior in Complex Interfacial Systems. Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Sibener, Steven J. [University of Chicago, IL (United States)


    This research program explored the efficacy of using molecular-level manipulation, imaging and scanning tunneling spectroscopy in conjunction with supersonic molecular beam gas-surface scattering to significantly enhance our understanding of chemical processes occurring on well-characterized interfaces. One program focus was on the spatially-resolved emergent behavior of complex reaction systems as a function of the local geometry and density of adsorbate-substrate systems under reaction conditions. Another focus was on elucidating the emergent electronic and related reactivity characteristics of intentionally constructed single and multicomponent atom- and nanoparticle-based materials. We also examined emergent chirality and self-organization in adsorbed molecular systems where collective interactions between adsorbates and the supporting interface lead to spatial symmetry breaking. In many of these studies we combined the advantages of scanning tunneling (STM) and atomic force (AFM) imaging, scanning tunneling local electronic spectroscopy (STS), and reactive supersonic molecular beams to elucidate precise details of interfacial reactivity that had not been observed by more traditional surface science methods. Using these methods, it was possible to examine, for example, the differential reactivity of molecules adsorbed at different bonding sites in conjunction with how reactivity is modified by the local configuration of nearby adsorbates. At the core of this effort was the goal of significantly extending our understanding of interfacial atomic-scale interactions to create, with intent, molecular assemblies and materials with advanced chemical and physical properties. This ambitious program addressed several key topics in DOE Grand Challenge Science, including emergent chemical and physical properties in condensed phase systems, novel uses of chemical imaging, and the development of advanced reactivity concepts in combustion and catalysis including carbon

  17. Reactive transport in the complex heterogeneous alluvial aquifer of Fortymile Wash, Nevada. (United States)

    Soltanian, Mohamad Reza; Sun, Alexander; Dai, Zhenxue


    Yucca Mountain, Nevada, had been extensively investigated as a potential deep geologic repository for storing high-level nuclear wastes. Previous field investigations of stratified alluvial aquifer downstream of the site revealed that there is a hierarchy of sedimentary facies types. There is a corresponding log conductivity and reactive surface area subpopulations within each facies at each scale of sedimentary architecture. Here we use a Lagrangian-based transport model in order to analyze radionuclide dispersion in the saturated alluvium of Fortymile Wash, Nevada. First, we validate the Lagrangian model using high-resolution flow and reactive transport simulations. Then, we used the validated model to investigate how each scale of sedimentary architecture may affect long-term radionuclide transport at Yucca Mountain. Results show that the reactive solute dispersion developed by the Lagrangian model matches the ensemble average of numerical simulations well. The link between the alluvium spatial variability and reactive solute dispersion at different spatiotemporal scales is demonstrated using the Lagrangian model. The longitudinal dispersivity of the reactive plume can be on the order of hundreds to thousands of meters, and it may not reach its asymptotic value even after 10,000 years of travel time and 2-3 km of travel distance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Synthesis and Reactivity of [1,2,4]Triazolo-annelated Quinazolines

    Directory of Open Access Journals (Sweden)

    Rashad A. Al-Salahi


    Full Text Available This paper reports the synthesis of phenyl-substituted 2-alkoxy(methylsulfanyl-1,2,4-triazolo[1,5-a]quinazolines starting from N-cyanoimidocarbonates and substituted hydrazinobenzoic acids as building blocks. Thionation or chlorination of the inherent lactam moiety in the target compounds followed by treatment with multifunctional nucleophiles provided access to a variety of derivatives.


    Directory of Open Access Journals (Sweden)

    Marcellino Rudyanto


    Full Text Available Synthesis of cinnamic acid and its six derivatives has been done by employing Knoevenagel reaction. Benzaldehyde, 4-butylbenzaldehyde, 4-t-butylbenzaldehyde, 4-butoxybenzaldehyde, 4-phenylbenzaldehyde, 5-bromo-2,4-dimethoxybenzaldehyde, and 5-bromo-2,3-dimethoxybenzaldehyde were reacted with malonic acid in pyridine – piperidine to give cinnamic acid (85,3%, 4-butylcinnamic acid (69,3%, 4-t-butylcinnamic acid (77,7%, 4-butoxycinnamic acid (64,5%, 4-phenylcinnamic acid (65,5%, 5-bromo-2,4-dimethoxycinnamic acid (53,2% and 5-bromo-2,4-dimethoxycinnamic acid (57,2%, respectively. It was disclosed that 4-alkyl, 4-alkoxy, 4-aryl, dan 2-alkoxy groups decrease the reactivity of carbonyl carbon of benzaldehyde.   Keywords: cinnamic acid, cinnamic acid derivatives, Knoevenagel reaction

  20. Design, synthesis, and evaluation of carnosine derivatives as selective and efficient sequestering agents of cytotoxic reactive carbonyl species. (United States)

    Vistoli, Giulio; Orioli, Marica; Pedretti, Alessandro; Regazzoni, Luca; Canevotti, Renato; Negrisoli, Gianpaolo; Carini, Marina; Aldini, Giancarlo


    Carnosine aryl derivatives as sequestering agents of RCS: Reactive carbonyl species (RCS) are cytotoxic mediators representing a novel drug target, as they are presumed to play a pathogenic role in several diseases. Carnosine is a selective RCS-sequestering agent, but is rapidly hydrolyzed by serum carnosinase. Herein we describe the in silico design, synthesis, and evaluation of a set of carnosine aryl derivatives.Reactive carbonyl species (RCS) are important cytotoxic mediators generated by lipid oxidation of polyunsaturated fatty acids (PUFAs) and represent a novel drug target, as they are presumed to play a pathogenic role in several diseases. L-Carnosine (L-CAR, beta-alanyl-L-histidine) is a specific detoxifying agent of RCS, but is rapidly hydrolyzed in human serum by carnosinase, a specific dipeptidase. Herein we describe the in silico design, synthesis, and biological evaluation of carnosine derivatives that are resistant to carnosinase and that have increased quenching efficacy. Stability against carnosinase-mediated turnover was achieved by isomerization of the histidine residue, leading to D-carnosine (D-CAR, beta-alanyl-D-histidine), which maintains the same quenching activity of L-carnosine. A molecular modeling approach was then used to design derivatives characterized by an increased quenching efficacy. The most promising candidates were synthesized, and their stability and quenching activity were evaluated. This study describes a set of aryl derivatives that are characterized by high stability in human plasma and a quenching activity toward 4-hydroxy-trans-2-nonenal (HNE), chosen as a model of RCS, up to threefold greater than D-carnosine.

  1. Synthesis, Spectral and Thermal Studies of New Rutin Vanadyl Complexes

    Directory of Open Access Journals (Sweden)

    Rodica Olar


    Full Text Available Complexes between oxovanadium (IV cation and flavonoid derivatives were developed recently in order to increase the intestinal absorption and to reduce the toxicity of vanadium compounds. For these reasons, is interesting to investigate the complexation process between flavonoid rutin (Rut and vanadyl cation in order to isolate new complexes. Two new complexes [VO(Rut(H2O2](SO40.5×2H2O and [VO(Rut2]×4H2O have been obtained and characterized by elemental and thermal analyses and several spectroscopic techniques (ESI-MS, IR, UV-Vis, fluorescence. The studies concerning complex formation between vanadyl and rutin (Rut performed in different solutions show the formation of mononuclear complexes with 1:1 and 1:2 metal to ligand stoichiometry.

  2. Study on complexity of Sutong Bridge's objectives system and its meta-synthesis management

    Institute of Scientific and Technical Information of China (English)

    Fa Yueping; Li Zhen


    Objectives define the boundaries of complex engineering system. It is a hard work to identify the specific objectives of a complex engineering system. The objectives system development needs a complicated process, from nix to prototype, and to final definition. The total process will cover the following course: from chaos to well-ordered; from qualitativeness to combination of quantitativeness and qualitativenss, then from qualitativeness to quantitativeness (a recurrent process), expert experience and theoretical science, rationality and sensibility, synthesis analysis and meta-synthesis, routinization and non-routinization. Such process is explicit in phase development yet overlapped; mutually confined yet mutuaLly independent; permeated conflicts yet pregnant in harmony. This article explores the complexity of Sutong Bridge's objectives development and the process of meta-synthesis in the Sutong Bridge engineering.

  3. Wave field synthesis of moving virtual sound sources with complex radiation properties. (United States)

    Ahrens, Jens; Spors, Sascha


    An approach to the synthesis of moving virtual sound sources with complex radiation properties in wave field synthesis is presented. The approach exploits the fact that any stationary sound source of finite spatial extent radiates spherical waves at sufficient distance. The angular dependency of the radiation properties of the source under consideration is reflected by the amplitude and phase distribution on the spherical wave fronts. The sound field emitted by a uniformly moving monopole source is derived and the far-field radiation properties of the complex virtual source under consideration are incorporated in order to derive a closed-form expression for the loudspeaker driving signal. The results are illustrated via numerical simulations of the synthesis of the sound field of a sample moving complex virtual source.

  4. Synthesis, structural characterization and thermal properties of copper and silver silyl complexes. (United States)

    Sgro, Michael J; Piers, Warren E; Romero, Patricio E


    The synthesis of copper and silver silyl complexes containing either N-heterocyclic carbenes or nitrogen donors is described. Alterations made to both the neutral donor ligands as well as the silyl group provided access to a number of different compounds. Many of the complexes synthesized were studied in the solid state and the effect of the donor ligand on the final structure of the complexes was examined. The thermal properties of the complexes were explored using thermogravimetric analysis, differential scanning calorimetry and sublimations. Some of the complexes synthesized were demonstrated to be promising volatile metal precursors.

  5. Synthesis of copper/nickel nanoparticles using newly synthesized Schiff-base metals complexes and their cytotoxicity/catalytic activities. (United States)

    Aazam, Elham S; El-Said, Waleed Ahmed


    Transition metal complexes compounds with Schiff bases ligand representing an important class of compounds that could be used to develop new metal-based anticancer agents and as precursors of metal NPs. Herein, 2,3-bis-[(3-ethoxy-2-hydroxybenzylidene)amino]but-2-enedinitrile Schiff base ligand and its corresponding copper/nickel complexes were synthesized. Also, we reported a facile and rapid method for synthesis nickel/copper nanoparticles based on thermal reduction of their complexes. Free ligand, its metal complexes and metals nanoparticles have been characterized based on elemental analysis, transmission electron microscopy, powder X-ray diffraction, magnetic measurements and by various spectroscopic (UV-vis, FT-IR, (1)H NMR, GC-MS) techniques. Additionally, the in vitro cytotoxic activity of free ligand and its complexes compounds were assessed against two cancer cell lines (HeLa and MCF-7 cells)and one healthy cell line (HEK293 cell). The copper complex was found to be active against these cancer cell lines at very low LD50 than the free ligand, while nickel complex did not show any anticancer activity against these cell lines. Also, the antibacterial activity of as-prepared copper nanoparticles were screened against Escherichia coli, which demonstrated minimum inhibitory concentration and minimum bactericidal concentration values lower than those values of the commercial Cu NPs as well as the previous reported values. Moreover, the synthesized nickel nanoparticles demonstrated remarkable catalytic performance toward hydrogenation of nitrobenzene that producing clean aniline with high selectivity (98%). This reactivity could be attributed to the high degree of dispersion of Ni nanoparticles. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Synthesis and electrochemical preformances of tribasic and tetrabasic lead sulfates prepared by reactive grinding (United States)

    Grugeon-Dewaele, S.; Laruelle, S.; Joliveau-Vallat, F.; Torcheux, L.; Delahaye-Vidal, A.

    Tribasic lead sulfate (3BS) and tetrabasic lead sulfate (4BS), used as precursors of the positive active material in the lead/acid batteries, were prepared by a new method: reactive grinding. The effects of various experimental parameters (stoichiometry, hygrometry of the starting compounds, duration of mechanical treatment) upon the nature and morphological features of the resulting phase were investigated. Among them, hygrometry turned out to be the most critical one. With water in excess, only 3BS was produced while dry reagents led to 4BS. In both cases, samples with a small particle size and high reactivity were obtained. In order to evaluate the influence of the morphology upon the electrochemical performances of such grinding produced samples, the capacity was measured and compared with that of traditional 3BS and 4BS samples.

  7. Linear Copolymer of N-Isopropylacrylamide and 2-Hydroxyethylacrylate: Synthesis, Characterization and Monomer Reactivity Ratios

    Directory of Open Access Journals (Sweden)

    Nakan U


    Full Text Available Сopolymerization of N-isopropylacrylamide (NIPAAm with 2-hydroxyethyl acrylate (2-HEA carried out by solvent ethanol solution method, at 600C, using Azoisobutyronitrile (AIBN as an initiator. The hydrophilic copolymers were characterized by elemental analysis, DSC, TGA and turbidimetric method. The results showed thermal stability increase with increase of NIPAAm in the copolymers. It was found that copolymer solutions have lower critical solution temperature (by turbidimetric analysis. The reactivity ratios of monomers were determined using linear methods like Fineman-Ross and Kelen-Tudos. The reactivity ratios of r1 and r2 were found to be 0,86, 0,72 and 1,02, 1,04 respectively.

  8. Studies on the Synthesis,Characterization and Properties of the Reactive Thermotropic Liquid Crystalline Polymer

    Institute of Scientific and Technical Information of China (English)


    1 Introduction Four species of reactive thermotropic liquid crystalline polymer (LCMC) with different relative molecular weight were synthesized in this work (see scheme 1, n=2, 6, 10, ∞.n means number of repeat structure unit). Their structure, morphology and properties were investigated systemically by differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Wide-angle X-ray diffraction (WAXD), polarizing opticalmicroscopy (POM) and ubb...

  9. Reactive Coevaporation Synthesis and Characterization of SrTiO3 Thin Films (United States)

    Yamaguchi, Hiromu; Matsubara, Shogo; Miyasaka, Yoichi


    SrTiO3 thin films were prepared by the reactive coevaporation method, where the Ti and Sr metals were evaporated in oxygen ambient with an E-gun and K-cell, respectively. A uniform depth profile in composition was achieved by altering the Ti evaporation rate according to the Sr evaporation rate change. A typical dielectric constant of 170 was measured on films of 75 nm in thickness. The in-situ annealing in oxygen plasma reduced the leakage current.

  10. Investigation of PAA/PVDF-NZVI hybrids for metronidazole removal: synthesis, characterization, and reactivity characteristics. (United States)

    Yang, Jiacheng; Wang, Xiangyu; Zhu, Minping; Liu, Huiling; Ma, Jun


    For the first time, the removal process of metronidazole (MNZ) from aqueous solutions over nano zerovalent iron (NZVI) encapsulated within poly(acrylic acid) (PAA)/poly(vinylidene fluoride) (PVDF) membranes was reported. The resultant composite (PPN) demonstrated high reactivity, excellent stability and reusability over the reaction course. Such excellent performance might be attributed to the presence of the charged carboxyl groups in PVDF membrane support, which could enhance NZVI dispersion and improve its longevity. Results showed that a lower initial concentration and higher reaction temperature facilitated the removal of MNZ by PPN, and that the acidic and neutral conditions generally exhibited more favorable effect on MNZ removal than the alkaline ones. Kinetics of the MNZ removal by PPN was found to follow a two-parameter pseudo-first-order decay model well, and the activation energy of the MNZ degradation by PPN was determined to be 30.49kJ/mol. The presence of chloride ions slightly enhanced the reactivity of PPN with MNZ, whereas sulfate ions inhibited its reactivity. In addition, MNZ degradation pathways by PPN were proposed based on the identified intermediates. This study suggests that PPN composite possessing excellent performance may be a promising functional material to pretreat antibiotic wastewaters.

  11. Synthesis and characterization of carboxymethyl potato starch and its application in reactive dye printing. (United States)

    Zhang, Bing; Gong, Honghong; Lü, Shaoyu; Ni, Boli; Liu, Mingzhu; Gao, Chunmei; Huang, Yinjuan; Han, Fei


    Carboxymethyl potato starch (CMPS) was synthesized with a simple dry and multi-step method as a product of the reaction of native potato starch and monochloroacetic acid in the presence of sodium hydroxide. The influence of the molar ratio of sodium hydroxide to anhydroglucose unit, the volume of 95% (v/v) ethanol, the rotation rate of motor driven stirrer and the reaction time for degree of substitution (DS) were evaluated. The product was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffractometry (XRD). FTIR spectrometry showed new bonds at 1618 and 1424 cm⁻¹ when native starch underwent carboxymethylation. SEM pictures showed that the smooth surface of native starch particles was mostly ruptured. XRD revealed that starch crystallinity was reduced after carboxymethylation. The viscosity of the mixture paste of carboxymethyl starch and sodium alginate (SA) was measured using a rotational viscometer. In addition, the applied effect of mixed paste in reactive dye printing was examined by assessing the fabric stiffness, color yield and sharp edge to the printed image in comparison with SA. And the results indicated that the mixed paste could partially replace SA as thickener in reactive dye printing. The study also showed that the method was low cost and eco-friendly and the product would have an extensive application in reactive dye printing. Copyright © 2012 Elsevier B.V. All rights reserved.


    Institute of Scientific and Technical Information of China (English)

    Qing-hua Duan; Tao-yi Zhang; Kui-lin Deng; Ping Xie; Rong-ben Zhang


    A novel ordered reactive oligomeric ladderlike copolymethyl-aminopropylsilsesquioxane (Me-AP-T), was successfully synthesized by an efficient hydrosilylation graft reaction of 1,1,1-trimethyl-N-2-propenyl-silanamine with a reactive oligomeric ladderlike copolymethyl-hydrosilsesquioxane (Me-H-T), which was prepared by "supramolecular chemistry-dictated stepwise coupling polymerization" process. FT-IR, 1H- and 29Si-NMR spectra show that hydrosilylation reaction proceeds completely. Moreover, 1H-NMR spectra also indicate that both the molar ratios of ≡SiMe group to Si-H and ≡ SiMe group to ≡ SiPrNH2 are approximately 1:1 respectively based on the ratio of integrated resonance areas of the different groups. XRD analysis and 29Si-NMR spectra are used for investigating the ladderlike structure of the polymers. A high Tg (128.38℃) of Me-AP-T shown in DSC measurement implies that the ordered reactive Me-AP-T macromolecules have much stiff chains.

  13. Versatile synthesis of end-reactive polyrotaxanes applicable to fabrication of supramolecular biomaterials

    Directory of Open Access Journals (Sweden)

    Atsushi Tamura


    Full Text Available Cyclodextrin (CD-threaded polyrotaxanes (PRXs with reactive functional groups at the terminals of the axle polymers are attractive candidates for the design of supramolecular materials. Herein, we describe a novel and simple synthetic method for end-reactive PRXs using bis(2-amino-3-phenylpropyl poly(ethylene glycol (PEG-Ph-NH2 as an axle polymer and commercially available 4-substituted benzoic acids as capping reagents. The terminal 2-amino-3-phenylpropyl groups of PEG-Ph-NH2 block the dethreading of the α-CDs after capping with 4-substituted benzoic acids. By this method, two series of azide group-terminated polyrotaxanes (benzylazide: PRX-Bn-N3, phenylazide: PRX-Ph-N3, were synthesized for functionalization via click reactions. The PRX-Bn-N3 and PRX-Ph-N3 reacted quickly and efficiently with p-(tert-butylphenylacetylene via copper-catalyzed click reactions. Additionally, the terminal azide groups of the PRX-Bn-N3 could be modified with dibenzylcyclooctyne (DBCO-conjugated fluorescent molecules via a copper-free click reaction; this fluorescently labeled PRX was utilized for intracellular fluorescence imaging. The method of synthesizing end-reactive PRXs described herein is simple and versatile for the design of diverse functional PRXs and can be applied to the fabrication of PRX-based supramolecular biomaterials.

  14. Synthesis and reactivity of single-phase Be{sub 17}Ti{sub 2} intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae-Hwan, E-mail: [Breeding Functional Materials Development Group, Sector of Fusion Research and Development, Japan Atomic Energy Agency (Japan); Iwakiri, Hirotomo; Furugen, Tatsuaki [Faculty of Education Elementary and Secondary School Teacher Training Program, University of the Ryukyus, Okinawa (Japan); Nakamichi, Masaru [Breeding Functional Materials Development Group, Sector of Fusion Research and Development, Japan Atomic Energy Agency (Japan)


    Highlights: • Preliminary synthesis of single-phase Be{sub 17}Ti{sub 2} was succeeded. • Reactivity difference between beryllium and beryllides may be caused by a lattice strain. • Oxidation of Be{sub 17}Ti{sub 2} at high temperatures results in the formation of TiO{sub 2}. • Simulation results reveal that a stable site for hydrogen at the center of tetrahedron exists. - Abstract: To investigate feasibility for application of Be{sub 17}Ti{sub 2} as a neutron multiplier as well as a refractory material, single-phase Be{sub 17}Ti{sub 2} intermetallic compounds were synthesized using an annealing heat treatment of the starting powder and a plasma sintering method. Scanning electron microscopic observations and X-ray diffraction measurements reveal that the single-phase Be{sub 17}Ti{sub 2} compounds were successfully synthesized. We examined the reactivity of Be{sub 17}Ti{sub 2} with 1% H{sub 2}O and discovered that a larger stoichiometric amount of Ti resulted in the formation of TiO{sub 2} on the surface at high temperatures. This oxidation may also contribute to an increase in both weight gain and generation of H{sub 2}. This suggests that the formation of the Ti-depleted Be{sub 17}Ti{sub 2−x} layer as a result of oxidation facilitates an increased reactivity with H{sub 2}O. To evaluate the safety aspects of Be{sub 17}Ti{sub 2}, we also investigated the hydrogen positions and solution energies based on the first principle. The calculations reveal that there are 10 theoretical sites, where 9 of these sites have hydrogen solution energies with a positive value (endothermic) and 1 site located at the center of a tetrahedron comprising two Be and two Ti atoms gives a negative value (exothermic).

  15. Synthesis and structural characterization of pyrazole and pyrazole niobocene complexes

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo-Hermosilla, F.; Jalon, F.A.; Otero, A.; Villasenor, E. [Departamento de Quimica Inorganica. Organica y Bioquimica, Facultad de Quimicas. Universidad de Castilla-La Mancha (Spain)


    The first pyrazolyl niobocene complexes were prepared by reacting the trihydride complex Nb/eta``5-C{sub 5}H{sub 4}(SiMe{sub 3}){sub 2}H{sub 3} with pyrazole. 3-methyl pyrazole and tetrafluoroborate salt of protonated bis (pyrazole-1-il)methane. (Author) 20 refs.

  16. Synthesis, characterization and antimicrobial studies of Schiff base complexes (United States)

    Zafar, Hina; Ahmad, Anis; Khan, Asad U.; Khan, Tahir Ali


    The Schiff base complexes, MLCl2 [M = Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)] have been synthesized by the template reaction of respective metal ions with 2-acetylpyrrole and 1,3-diaminopropane in 1:2:1 M ratio. The complexes have been characterized by elemental analyses, ESI - mass, NMR (1H and 13C), IR, XRD, electronic and EPR spectral studies, magnetic susceptibility and molar conductance measurements. These studies show that all the complexes have octahedral arrangement around the metal ions. The molar conductance measurements of all the complexes in DMSO indicate their non-electrolytic nature. The complexes were screened for their antibacterial activity in vitro against Gram-positive (Streptococcus pyogenes) and Gram-negative (Klebsiella pneumoniae) bacteria. Among the metal complexes studied the copper complex [CuLCl2], showed highest antibacterial activity nearly equal to standard drug ciprofloxacin. Other complexes also showed considerable antibacterial activity. The relative order of activity against S. Pyogenes is as Cu(II) > Zn(II) > Co(II) = Fe(II) > Ni(II) and with K. Pneumonia is as Cu(II) > Co(II) > Zn(II) > Fe(II) > Ni(II).

  17. The Synthesis of Glycosyl Phosphite-Pt(Ⅱ) Complexes

    Institute of Scientific and Technical Information of China (English)

    Ling Hua CAO; Hong Yun GAO; Chuan Jian ZHOU; Yu Ting LIU


    Ethylene glycol phosphorochloridite 1 or catechol phosphorochloridite 2 reacted with isopropylidene derivatives of D-glucose, D-galactose, D-mannose and D-fructose, a series of glycosyl phosphites were obtained. These glycosyl phosphites form optically active complexes with simple Pt (Ⅱ) salts. Pt (Ⅱ) is coordinated to the phosphorus atom, most of the metal complexes are quite stable.

  18. A new metalation complex for organic synthesis and polymerization reactions (United States)

    Hirshfield, S. M.


    Organometallic complex of N,N,N',N' tetramethyl ethylene diamine /TMEDA/ and lithium acts as metalation intermediate for controlled systhesis of aromatic organic compounds and polymer formation. Complex of TMEDA and lithium aids in preparation of various organic lithium compounds.

  19. Investigating the Causal Relationship of C-Reactive Protein with 32 Complex Somatic and Psychiatric Outcomes

    DEFF Research Database (Denmark)

    Prins, Bram P; Abbasi, Ali; Wong, Anson


    BACKGROUND: C-reactive protein (CRP) is associated with immune, cardiometabolic, and psychiatric traits and diseases. Yet it is inconclusive whether these associations are causal. METHODS AND FINDINGS: We performed Mendelian randomization (MR) analyses using two genetic risk scores (GRSs) as inst...

  20. Fundamental reactivity of the Metal-Carbon bond in cyclometalated PNC-complexes

    NARCIS (Netherlands)

    Jongbloed, L.S.


    The activation of C-H bonds by transition metals and the reactivity of the corresponding metal-carbon bond are interesting research topics form different point of views. Catalytic C-H bond functionalization has emerged as a highly active research area for the development of green construction of Car

  1. Fundamental reactivity of the Metal-Carbon bond in cyclometalated PNC-complexes

    NARCIS (Netherlands)

    L.S. Jongbloed


    The activation of C-H bonds by transition metals and the reactivity of the corresponding metal-carbon bond are interesting research topics form different point of views. Catalytic C-H bond functionalization has emerged as a highly active research area for the development of green construction of Car

  2. The synthesis, design and applications of lanthanide cored complexes (United States)

    Phelan, Gregory David

    Novel luminescent materials based on lanthanide cored complexes have been designed and synthesized. The complexes consist of a beta-diketone ligand chelated to a lanthanide metal such as europium or gadolinium. A series of beta-diketone ligands were designed and synthesized. The ligands consist of a polycyclic aromatic sensitizer, phenanthrene, and a second functional group. The second groups consisted of another unit of phenanthrene, a dendritic structure, or a fluorinated alkyl chain. The europium complexes have been incorporated into organic light emitting devices that have a major emission at 615 nm and a maximum brightness of 300 cd/m2. The gadolinium complexes were used to dope into the resulting organic light emitting devices to help improve the efficiency of the device. The use of the gadolinium complexes results in a 25 fold increase in efficiency.

  3. Microwave assisted synthesis, spectral, magnetic and bioevolution of few Mn (II)-amide complexes

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Gaurav [Department of Chemistry, Govt. Engineering College, Bikaner (India); Verma, K. K.; Gudesaria, D. D.; Bhojak, N., E-mail: [GCRC, Department of Chemistry, Govt Dungar College, Bikaner-334003, Rajasthan (India)


    The importance and versatility of amide group containing ligands have promoted the selection of this class of ligands and their complexes for the study. The present work describes the synthesis, spectral and biological investigations on the complexes of amides derived from heterocyclic amines with Mn (II) ions. Four ligands derived 2-aminopyridine and their complexes with Mn (II) have been synthesized. A method for the synthesis of complexes has been developed by the use of microwave irradiation which is in agreement to Green chemistry approach. The complexes have been characterized on the basis of elemental analysis, infrared, electronic, ESR spectra and magnetic susceptibility studies. The diffuse reflectance spectrum of the complexes show bands in the region 20,000 cm{sup −1} to 26,000 cm{sup −1} assignable to {sup 6}A{sub 1g} → {sup 4}T{sub 2g} and {sup 6}A{sub 1g} → {sup 4}E{sub 1g} transitions. These are also typical of tetrahedral environment around the manganese. The magnetic moment (5.80 BM) of the complex indicates high spin tetrahedral environment. The microwave method of synthesis of complexes have been found easier, convenient and ecofriendly. Antimicrobial activities of compounds were also carried out against bacteria and fungi. Further minimal inhibitory concentration (MIC) was also determined for each compound.

  4. Microwave assisted synthesis, spectral, magnetic and bioevolution of few Mn (II)-amide complexes (United States)

    Joshi, Gaurav; Verma, K. K.; Gudesaria, D. D.; Bhojak, N.


    The importance and versatility of amide group containing ligands have promoted the selection of this class of ligands and their complexes for the study. The present work describes the synthesis, spectral and biological investigations on the complexes of amides derived from heterocyclic amines with Mn (II) ions. Four ligands derived 2-aminopyridine and their complexes with Mn (II) have been synthesized. A method for the synthesis of complexes has been developed by the use of microwave irradiation which is in agreement to Green chemistry approach. The complexes have been characterized on the basis of elemental analysis, infrared, electronic, ESR spectra and magnetic susceptibility studies. The diffuse reflectance spectrum of the complexes show bands in the region 20,000 cm-1 to 26,000 cm-1 assignable to 6A1g → 4T2g and 6A1g → 4E1g transitions. These are also typical of tetrahedral environment around the manganese. The magnetic moment (5.80 BM) of the complex indicates high spin tetrahedral environment. The microwave method of synthesis of complexes have been found easier, convenient and ecofriendly. Antimicrobial activities of compounds were also carried out against bacteria and fungi. Further minimal inhibitory concentration (MIC) was also determined for each compound.

  5. Synthesis of a Benzodiazepine-derived Rhodium NHC Complex by C-H Bond Activation

    Energy Technology Data Exchange (ETDEWEB)

    Bergman, Roberg G.; Gribble, Jr., Michael W.; Ellman, Jonathan A.


    The synthesis and characterization of a Rh(I)-NHC complex generated by C-H activation of 1,4-benzodiazepine heterocycle are reported. This complex constitutes a rare example of a carbene tautomer of a 1,4-benzodiazepine aldimine stabilized by transition metal coordination and demonstrates the ability of the catalytically relevant RhCl(PCy{sub 3}){sub 2} fragment to induce NHC-forming tautomerization of heterocycles possessing a single carbene-stabilizing heteroatom. Implications for the synthesis of benzodiazepines and related pharmacophores via C-H functionalization are discussed.

  6. Synthesis and Reactivity of (β-Amino-α-acylalkenyl)phenyliodonium Salts

    Institute of Scientific and Technical Information of China (English)

    ZHANG Peng-Fei; CHEN Zhen-Chu


    @@ During the last few years alkenyl(phenyl)iodonium salts have risen from mere chemical curiosities to valuable synthetic intermediates. [1] Because of an excellent leaving group ability of a phenyliodonyl moiety, alkenyl(phenyl) iodonium salts undergo nucleophilic vinyl substitutions under mild conditions, thus providing a useful route for the synthesis of various kinds of olefins. Recently, some of functionalized alkenyl iodonium salts have been prepared. [2

  7. Synthesis, Crystal Structure, Spectroscopic Properties and Potential Biological Activities of Salicylate‒Neocuproine Ternary Copper(II Complexes

    Directory of Open Access Journals (Sweden)

    Lenka Kucková


    Full Text Available Mixed ligand copper(II complexes containing derivatives of salicylic acid and heterocyclic ligands with nitrogen donor atoms have been the subject of various studies and reviews. In this paper, synthesis and characterization of the ternary copper(II complexes of neocuproine (2,9-dimethyl-1,10-phenanthroline, Neo and salicylate ligands (Sal are reported. In addition, the crystal structures of ([Cu(H2O(5-Cl-Sal(Neo] (1, [Cu(μ-Sal(Neo]2 (2, Cu2(μ-5-Cl-Sal(5-Cl-HSal2(Neo2]·EtOH (3 were determined. In order to compare structural and biological properties of the prepared complexes, spectroscopic and biological studies were performed. Results of X-ray diffraction show that prepared complexes form three types of crystal structures in a given system: monomeric, dimeric and dinuclear complex. The preliminary study on the DNA cleavage activity has shown that the complexes under study behave as the chemical nucleases in the presence of added hydrogen peroxide with slight differences in the activity (1 > 2 > 3. The complexes 1 and 2 exhibited nuclease activity itself indicating the interaction of complexes with the DNA. It has been proposed that the enhanced destructive effect of the complexes 1 and 2 on the DNA is a result of two possible mechanisms of action: (i the conversion of closed circular DNA (form I to the nicked DNA (form II caused by the copper complex itself and (ii damage of DNA by Reactive Oxygen Species (ROS—products of the interaction of copper with hydrogen peroxide by means of Fenton reaction (hydroxyl radicals. Thus the biological activity of the prepared Cu(II complexes containing derivatives of salicylic acid and phenanthroline molecules is substantiated by two independent mechanisms. While derivatives of salicylic acids in the coordination sphere of copper complexes are responsible for radical-scavenging activity (predominantly towards superoxide radical anion, the presence of chelating ligand 2,9-dimethyl-1,10-phenanthroline

  8. A theory for bioinorganic chemical reactivity of oxometal complexes and analogous oxidants: the exchange and orbital-selection rules. (United States)

    Usharani, Dandamudi; Janardanan, Deepa; Li, Chunsen; Shaik, Sason


    Over the past decades metalloenzymes and their synthetic models have emerged as an area of increasing research interest. The metalloenzymes and their synthetic models oxidize organic molecules using oxometal complexes (OMCs), especially oxoiron(IV)-based ones. Theoretical studies have helped researchers to characterize the active species and to resolve mechanistic issues. This activity has generated massive amounts of data on the relationship between the reactivity of OMCs and the transition metal's identity, oxidation state, ligand sphere, and spin state. Theoretical studies have also produced information on transition state (TS) structures, reaction intermediates, barriers, and rate-equilibrium relationships. For example, the experimental-theoretical interplay has revealed that nonheme enzymes carry out H-abstraction from strong C-H bonds using high-spin (S = 2) oxoiron(IV) species with four unpaired electrons on the iron center. However, other reagents with higher spin states and more unpaired electrons on the metal are not as reactive. Still other reagents carry out these transformations using lower spin states with fewer unpaired electrons on the metal. The TS structures for these reactions exhibit structural selectivity depending on the reactive spin states. The barriers and thermodynamic driving forces of the reactions also depend on the spin state. H-Abstraction is preferred over the thermodynamically more favorable concerted insertion into C-H bonds. Currently, there is no unified theoretical framework that explains the totality of these fascinating trends. This Account aims to unify this rich chemistry and understand the role of unpaired electrons on chemical reactivity. We show that during an oxidative step the d-orbital block of the transition metal is enriched by one electron through proton-coupled electron transfer (PCET). That single electron elicits variable exchange interactions on the metal, which in turn depend critically on the number of

  9. Synthesis, spectroscopic, thermogravimetric and antimicrobial studies of mixed ligands complexes (United States)

    Mahmoud, Walaa H.; Mahmoud, Nessma F.; Mohamed, Gehad G.; El-Sonbati, Adel Z.; El-Bindary, Ashraf A.


    An interesting series of mixed ligand complexes have been synthesized by the reaction of metal chloride with guaifenesin (GFS) in the presence of 2-aminoacetic acid (HGly) (1:1:1 molar ratio). The elemental analysis, magnetic moments, molar conductance, spectral (UV-Vis, IR, 1H NMR and ESR) and thermal studies were used to characterize the isolated complexes. The molecular structure of GFS is optimized theoretically and the quantum chemical parameters are calculated. The IR showed that the ligand (GFS) acts as monobasic tridentate through the hydroxyl, phenoxy etheric and methoxy oxygen atoms and co-ligand (HGly) as monobasic bidentate through the deprotonated carboxylate oxygen atom and nitrogen atom of amino group. The molar conductivities showed that all the complexes are non-electrolytes except Cr(III) complex is electrolyte. Electronic and magnetic data proposed the octahedral structure for all complexes under investigation. ESR spectrum for Cu(II) revealed data which confirm the proposed structure. Antibacterial screening of the compounds were carried out in vitro on gram positive (Bacillus subtilis and Staphylococcus aureus), gram negative (Escherichia coli and Neisseria gonorrhoeae) bacteria and for in vitro antifungal activity against Candida albicans organism. However, some complexes showed more chemotherapeutic efficiency than the parent GFS drug. The complexes were also screened for their in vitro anticancer activity against the breast cell line (MFC7) and the results obtained showed that they exhibit a considerable anticancer activity.

  10. [Decolorization of reactive blue P-3R with microsphere-supported binuclear Manganese complex as a novel heterogeneous CWPO catalyst]. (United States)

    Song, Min; Zhang, Lin-Ping; Zhong, Yi; Xu, Hong; Mao, Zhi-Ping


    Binuclear manganese complex (MnL), with high catalytic activity, was encapsulated into ethyl cellulose microspheres via a microencapsulation technique. The characterization of the catalyst through ICP, UV-VIS, SEM and TEM revealed that MnL was well distributed within the ethyl cellulose matrix. The results of UV-VIS confirmed the structural integrity of MnL after the encapsulation process. The MnL loaded microspheres exhibited an excellent catalytic property in the oxidative decolorization of Reactive Blue P-3R, which was used to simulate the dyestuff wastewater. The dye solution was completely decolorized under the catalyzing action of these microspheres. What's more, these MnL loaded microspheres could be reused for at least 4 times and the decolorization degree of Reactive Blue P-3R was maintained above 70%. The results demonstrated the potential application of the microsphere-supported MnL as a novel heterogeneous CWPO catalyst for the decolorization of wastewater containing dyestuff.

  11. Synthesis and Characterization of Rare Earth Complexes of Ferrocenylcarbonylhydrazine

    Institute of Scientific and Technical Information of China (English)

    边占喜; 董彬; 李保国


    Rare earth complexes of ferrocenylcarbonylhydrazine Ln(FH)x(ClO4)3*nH2O (where Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, x=3; Ln = Er, Tm, Yb, Lu, x=4; n=2~6, FH=ferrocenylcarbonylhydrazin) were synthesized and characterized by elemental analyses, MS, IR and 1H NMR spectra. The ligand FH is bidentate, coordinating through the carbonyl oxygen and the amino nitrogen atom. The redox properties of the ligand and its complexes were investigated using cyclic voltammetric method. The solid state fluorescence spectra of Sm, Tb and Dy complexes were also studied.

  12. Synthesis of Er-complexes for photonic applications (United States)

    Sofer, Zdenek; Třešňáková, Pavlína; Špirková, Jarmila; Rubáš, Stanislav; Kalábová, Martina


    We present a new approach of introducing erbium ions onto thin surface layers of silica glass substrates based on soaking of solution of erbium complexes. Different types of Er3+ complexes with 2,2‧-dipyridyle, 1,10-phenantroline, 8-hydroxyquinoline and ethylendiamine ligands and nitrate, thiocyanate and acetate anions were prepared. Composition of the complexes was determined by elementary analysis and by FT-IR spectroscopy. Decomposition temperature was measured by thermogravimetric analysis. Erbium doped surface layers exhibit strong photoluminescence with maximum on 1533 nm and full width at half maximum above 50 nm.

  13. Synthesis and in-vitro reactivation screening of imidazolium aldoximes as reactivators of sarin and VX-inhibited human acetylcholinesterase (hAChE). (United States)

    Sharma, Rahul; Gupta, Bhanushree; Sahu, Arvind Kumar; Acharya, Jyotiranjan; Satnami, Manmohan L; Ghosh, Kallol K


    Post-treatment of organophosphate (OP) poisoning involves the application of oxime reactivator as an antidote. Structurally different oximes are widely studied to examine their kinetic and mechanistic behavior against OP-inhibited cholinesterase enzyme. A series of structurally related 1,3-disubstituted-2-[(hydroxyiminomethyl)alkyl]imidazolium halides (5a-5e, 9a-9c) were synthesized and further evaluated for their in-vitro reactivation ability to reactivate sarin- and VX-inhibited human acetylcholinesterase (hAChE). The observed results were compared with the reactivation efficacy of standard reactivators; 2-PAM, obidoxime and HI-6. Amongst the synthesized oximes, 5a, 9a and 9b were found to be most potent reactivators against sarin-inhibited hAChE while in case of VX only 9a exhibited comparable reactivity with 2-PAM. Incorporation of pyridinium ring to the imidazole ring resulted in substantial increase in the reactivation strength of prepared reactivator. Physicochemical properties of synthesized reactivators have also been evaluated.

  14. Sandwich complex-containing macromolecules: property tunability through versatile synthesis. (United States)

    Abd-El-Aziz, Alaa S; Agatemor, Christian; Etkin, Nola


    Sandwich complexes feature unique properties as the physical and electronic properties of a hydrocarbon ligand or its derivative are integrated into the physical, electronic, magnetic, and optical properties of a metal. Incorporation of these complexes into macromolecules results in intriguing physical, electrical, and optical properties that were hitherto unknown in organic-based macromolecules. These properties are tunable through well-designed synthetic strategies. This review surveys many of the synthetic approaches that have resulted in tuning the properties of sandwich complex-containing macromolecules. While the past two decades have seen an ever-growing number of research publications in this field, gaps remain to be filled. Thus, we expect this review to stimulate research interest towards bridging these gaps, which include the insolubility of some of these macromolecules as well as expanding the scope of the sandwich complexes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Synthesis and Fluorescence of Novel Conjugated Europium Complex

    Institute of Scientific and Technical Information of China (English)

    安保礼; 龚孟濂; 叶剑清; 董俊萍; 李明星; 杨燕生


    A novel organic ligand, 6-(ortho-methyl-anilino carbonyl) 2-pyridine carboxylic acid (H-o-MAP), and the corresponding europium complex, tris(6-(ortho-methyl-anilino carbonyl) 2-pyridine carboxylato) europium (Ⅲ) (Eu-o-MAP) were designed and synthesized. The results show that solid Eu-o-MAP is a conjugated complex, emitting strong red fluorescence dominantly due to a ligand-sensitizd luminescence mechanism. The lifetimes of 5D0 of Eu3+ in the complex were examined using time-resolved spectroscopic analysis, and the lifetime values were (1.50±0.01) ms for solid Eu(o-MAP)3 and (1.10±0.01) ms for 1.0×10-5 mol*L-1 Eu(o-MAP)3 ethanol solution, respectively. Thermogravimetric analysis shows that the europium complex has good thermal stability.

  16. Copper(II) complex of 3-cinnamalideneacetylacetone: Synthesis and characterisation

    Indian Academy of Sciences (India)

    A Veeraraj; P Sami; N Raman


    A bidentate ligand derived from cinnamaldehyde and acetylacetone and its copper(II) complex have been synthesized and characterized by elemental analysis, UV-Vis, IR, ESR and magnetic susceptibility measurements. Magnetic susceptibility measurements, ESR and electronic spectral data indicate the presence of six coordinated Cu(II) ion. The ligand and complex are tested for antibacterial activity against Pseudomonas aeroginosa. They are found to show the antibacterial activity

  17. Synthesis of Optically Active Polystyrene Catalyzed by Monophosphine Pd Complexes. (United States)

    Jouffroy, Matthieu; Armspach, Dominique; Matt, Dominique; Osakada, Kohtaro; Takeuchi, Daisuke


    Cationic Pd(II) monophosphine complexes derived from α- and β-cyclodextrins (CDs) promote the homopolymerization of styrene under carbon monoxide pressure. Although reversible CO coordination takes place under catalytic conditions according to (13) C NMR studies with (13) C-enriched CO, both complexes catalyze the formation of CO-free styrene polymers. These macromolecules display optical activity as a result of the presence of stereoregular sequences within the overall atactic polymer.

  18. Method of synthesis of anhydrous thorium(IV) complexes (United States)

    Kiplinger, Jaqueline L; Cantat, Thibault


    Method of producing anhydrous thorium(IV) tetrahalide complexes, utilizing Th(NO.sub.3).sub.4(H.sub.2O).sub.x, where x is at least 4, as a reagent; method of producing thorium-containing complexes utilizing ThCl.sub.4(DME).sub.2 as a precursor; method of producing purified ThCl.sub.4(ligand).sub.x compounds, where x is from 2 to 9; and novel compounds having the structures: ##STR00001##

  19. Synthesis and spectral characterization of a decavanadate/chitosan complex


    ZHETCHEVA, Violeta Dimitrova KASSABOVA; PAVLOVA, Lilyana Parvanova


    A decavanadate/chitosan complex was synthesized by crosslinking chitosan with decavanadate anions at a pH of 3. The materials were characterized by Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), absorption spectroscopy (UV-Vis), and transmission electron microscopy (TEM). The spectroscopic results indicated that the decavanadate/chitosan complex was successfully obtained as result of an ionic crosslinking of the chi...

  20. Synthesis and Application of Azo Disperse Reactive Dyes derived from p-Aminobenzaldehyde

    Directory of Open Access Journals (Sweden)

    Iyabo Fasansi


    Full Text Available Disperse reactive dyes were synthesized by diazotizing p-aminobenzaldehyde and coupling with different substituted pyridones and 2-naphthol. The dyeing performance of the dyes was assessed on polyester, nylon, cotton and wool fabrics. The dyes obtained gave various shades of yellow with good depth, brightness and leveling properties on the fabrics. The dyed fabric showed fairly good to very good light fastness and very good to excellent fastness to washing, hot pressing and rubbing. The dyebath exhaustion on the polyester, nylon, wool and cotton fabrics was found to be very good and fixation on wool was better than on cotton fabric.

  1. Synthesis of click-reactive HPMA copolymers using RAFT polymerization for drug delivery applications

    DEFF Research Database (Denmark)

    Ebbesen, Morten F; Schaffert, D.H.; Crowley, Michael L


    This study describes a versatile strategy combining reversible addition fragmentation transfer (RAFT) polymerization and click chemistry to synthesize well-defined, reactive copolymers of N-(2-hydroxypropyl)methacrylamide (HPMA) for drug delivery applications. A novel azide containing monomer N-(3......-alkyne cycloaddition (CuAAC) was demonstrated by efficient conjugation (up to 92%) of phosphocholine, a near infrared dye, and poly(ethylene glycol) (PEG) with different substitution degrees, either alone or in combination. This study introduces a novel and versatile method to synthesize well-defined click...

  2. Reactive surface organometallic complexes observed using dynamic nuclear polarization surface enhanced NMR spectroscopy

    KAUST Repository

    Pump, Eva


    Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) is an emerging technique that allows access to high-sensitivity NMR spectra from surfaces. However, DNP SENS usually requires the use of radicals as an exogenous source of polarization, which has so far limited applications for organometallic surface species to those that do not react with the radicals. Here we show that reactive surface species can be studied if they are immobilized inside porous materials with suitably small windows, and if bulky nitroxide bi-radicals (here TEKPol) are used as the polarization source and which cannot enter the pores. The method is demonstrated by obtaining significant DNP enhancements from highly reactive complelxes [(equivalent to Si-O-)W(Me)(5)] supported on MCM-41, and effects of pore size (6.0, 3.0 and 2.5 nm) on the performance are discussed.

  3. Synthesis, Characterization and Biological Activity of an Intramolecular Stacking Zinc(Ⅱ) Complex

    Institute of Scientific and Technical Information of China (English)

    GAO, Enjun; LIU, Lei; ZHU, Mingchang; WU, Qiong


    The synthesis, crystallographic analysis and spectroscopic study of a zinc(Ⅱ) complex [Zn(bipy)(pmal)(H2O)]· 2H2O (bipy=2,2'-bipyfidine, pmal=phenylmalonic acid) were carded out. The complex has been investigated by the methods of X-ray crystallography, elemental analysis and IR spectra. The binding ability of the Zn(Ⅱ) complex to calf thymus (CT-DNA) was characterized by measuring the effects on the UV spectroscopy and fluorescence spectra of DNA. The agarose gel electrophoresis experimental results suggest that the ligand planaxity of complex has a significant effect on cleaving the pBR322 plasmid DNA.

  4. Photoreactive TiO2/carbon nanotube composites: synthesis and reactivity. (United States)

    Yao, Yuan; Li, Gonghu; Ciston, Shannon; Lueptow, Richard M; Gray, Kimberly A


    Electron-hole recombination limits the efficiency of TiO2 photocatalysis. We have investigated the efficacy with which anatase/carbon nanotube (CNT) composite materials reduce charge recombination and enhance reactivity. We synthesized nanostructured assemblies composed of different proportions of anatase (5 or 100 nm) and either single-or multi-walled CNTs. The composites were prepared using a simple low temperature process in which CNTs and anatase nanoparticles were dispersed in water, dehydrated at 80 degrees C, and dried at 104 degrees C. The structures of the various TiO2/CNT composites were characterized by scanning electron microscopy (SEM) and their function was tested by phenol oxidation. Charge recombination was compared by measuring the photoluminescence spectra of select composites. We found that a nanostructured composite assembled from the 100 nm anatase and single-walled CNTs (SWCNTs) exhibited enhanced and selective photocatalytic oxidation of phenol in comparison to both pure anatase and Degussa P25. A mechanism for the enhanced reactivity is proposed in which electrons are shuttled from TiO2 particles to the SWCNTs as a result of an optimal TiO2/ CNT arrangement that stabilizes charge separation and reduces charge recombination. In addition, the SWCNT assembly provides better catalyst-support (dispersal and connection) than multi-walled CNTs.

  5. Synthesis of zincosilicate mordenite using citric acid as complexing agent

    Institute of Scientific and Technical Information of China (English)

    MeiDong; JianjuoWang; YuhanSun


    The zincosilicate analog of zeolite mordenite was hydrothermally synthesized in the presence of citric acid and characterized with several spectroscopic techniques.The zeolite thus prepared had a higher crystallinity and Zn concentration in the framework compared with the one obtained in the absence of citric acid.XRD and FTIR provided evidence for the incorporation of Zn in the framework.Results of XAFS indicated a tetrahedral structure of Zn in the lattice framework with a Zn-O distancd of 0.1938nm.It is speculated that the citric acid might decrease the concentration of Zn2 in the synthesis mixture,there by preventing the unfavorable-formation of oxide or hydroxide species.2001 Elsevier Science B.V.All rights reserved.

  6. Microwave Assisted Synthesis Spectral and Antibacterial Investigations on Complexes of Mn(II) With Amide Containing Ligands


    N. Bhojak; D. D. Gudasaria; N. Khiwani; Jain, R.


    The present research work describes the synthesis, spectral and antibacterial studies on the complexes of Mn(II) with amide group containing ligands. Synthesis of complexes has been carried out by conventional method as well as by microwave method. The complexes have been characterized on the basis of elemental analysis, infrared, electronic spectra and magnetic susceptibility studies. The diffuse reflectance spectrums of the complexes show bands in the region 20,000 cm-1 to 26,000 cm-1 ass...

  7. New silver complexes with levofloxacin: Synthesis, characterization and microbiological studies (United States)

    Rusu, Aura; Hancu, Gabriel; Tóth, Gergő; Vancea, Szende; Toma, Felicia; Mare, Anca Delia; Man, Adrian; Niţulescu, George Mihai; Uivarosi, Valentina


    Levofloxacin is a third generation fluoroquinolone antibiotic with a broad-spectrum including both Gram positive bacteria and Gram negative bacteria, as well atypical bacteria. In order to extend the spectrum of activity and to add new biological effects, several metal complexes of levofloxacin have been obtained and reported recently. The aim of our study was to obtain new silver complexes with levofloxacin with potential broad spectrum antibacterial and antifungal activity. Therefore three new silver complexes of levofloxacin with the proposed chemical structures (levofloxacin)2Ag(NO3), (levofloxacin)2Ag(NO3)(CH3OH) and (levofloxacin)Ag(C6H6O7)·3H2O were synthesized. In order to characterize the obtained complexes elemental analysis, conductivity measurement, spectroscopic, and thermal methods were used. Optimized molecular structures were determined using DFT (density functional theory) analysis. The antibacterial activity against Gram negative and Gram positive bacteria and antifungal activity against Candida spp of the complexes was tested by determination of minimum inhibitory concentration through microtitre broth dilution method.

  8. Synthesis and luminescent properties of novel pyrazolone rare earth complexes

    Institute of Scientific and Technical Information of China (English)

    BAO Jiqing; TANG Chunhua; TANG Ruiren


    A novel pyrazolone pyridine-containing ligand,2,6-bis(l-phenyl-4-ethoxycarbonyl-5-pyrazolone-3-yl)pyridine(H2L)was designed and synthesized from Pyridine-2,6-dicarboxylic acid(1),and its Eu(Ⅲ)and Tb(Ⅲ)complexes were prepared.The 1igand and complexes were characterized in detailbased on FT-IR spectra,1H NMR,elemental ahalysis and thermal analysis,and the formula of Ln2L3·4H2O(Ln=Eu or Tb)of rare earth complexes was confirmed.The UV-vis absorption spectm and photoluminescence properties of the complexes were investigated,which showed that the Eu(Ⅲ)and Tb(Ⅲ)ions could be sensitized efficiently by the ligand(H2L)and emit the photoluminescence with high intensity, narrow half-peak width,and monochromic light.The results indicated that the complexes showed potential as excellent luminescent materials.

  9. Synthesis and evaluation of chitosan-Vitamin C complex

    Directory of Open Access Journals (Sweden)

    Tian X


    Full Text Available Chitosan is a biocompatible, biodegradable and non-toxic polysaccharide polymer. It dissolves in water only if the pH is lower than 6.5. To extend its range of application, many water-soluble derivatives have therefore been prepared. In this research, chitosan-vitamin C complex was synthesized and characterized with Fourier transformed infrared spectroscopy, differential scanning calorimetry and 1 H-NMR. The solubility of chitosan-vitamin C complex in distilled water was greatly improved. The ·O2 - scavenging activity of chitosan-vitamin C complex was compared with chitosan and vitamin C by measuring the auto-oxidation rate of pyrogallic acid. Results showed that the scavenging activity on ·O2 - by chitosan-vitamin C complex was stronger than that by CS. At low concentrations (< 0.05 mg/ml, the scavenging activity of chitosan-vitamin C complex was stronger than that of vitamin C, but after certain concentrations (>0.1mg/ml, its scavenging activity was lower than that of vitamin C.

  10. How students process equations in solving quantitative synthesis problems? Role of mathematical complexity in students’ mathematical performance

    Directory of Open Access Journals (Sweden)

    Bashirah Ibrahim


    Full Text Available We examine students’ mathematical performance on quantitative “synthesis problems” with varying mathematical complexity. Synthesis problems are tasks comprising multiple concepts typically taught in different chapters. Mathematical performance refers to the formulation, combination, and simplification of equations. Generally speaking, formulation and combination of equations require conceptual reasoning; simplification of equations requires manipulation of equations as computational tools. Mathematical complexity is operationally defined by the number and the type of equations to be manipulated concurrently due to the number of unknowns in each equation. We use two types of synthesis problems, namely, sequential and simultaneous tasks. Sequential synthesis tasks require a chronological application of pertinent concepts, and simultaneous synthesis tasks require a concurrent application of the pertinent concepts. A total of 179 physics major students from a second year mechanics course participated in the study. Data were collected from written tasks and individual interviews. Results show that mathematical complexity negatively influences the students’ mathematical performance on both types of synthesis problems. However, for the sequential synthesis tasks, it interferes only with the students’ simplification of equations. For the simultaneous synthesis tasks, mathematical complexity additionally impedes the students’ formulation and combination of equations. Several reasons may explain this difference, including the students’ different approaches to the two types of synthesis problems, cognitive load, and the variation of mathematical complexity within each synthesis type.

  11. Asymmetric synthesis of amino acid precursors in interstellar complex organics by circularly polarized light


    Takano, Yoshinori; Takahashi, Jun-ichi; Kaneko, Takeo; Marumo, Katsumi; Kobayashi, Kensei


    The asymmetric synthesis of amino acid precursors from complex organics have been performed. A gaseous mixture of carbon monoxide, ammonia and water (molecules which are among those identified in the interstellar medium) was irradiated with 3.0 MeV protons to obtain amino acid precursors within high-molecular-weight complex organics of up to 3,000 Da. The amino acid precursor products synthesized were then irradiated with right (R-) or left (L-) ultraviolet circularly polarized light (UV-CPL)...

  12. A uranium (VI) complex: Synthesis, structural and thermal kinetic analysis (United States)

    Goel, Nidhi


    A new complex [UO2(2,6-DNP)2phen] (1) (2,6-DNP = 2,6-dinitrophenol, phen = 1,10-phenanthroline) was synthesized, and identified by elemental analysis, IR, Powder XRD and single crystal X-ray crystallography. Crystal structure provides the abundant information's about the bonding and geometry around the U(VI) metal center. The thermal decomposition was studied by TG-DSC, and the kinetics of thermolysis was investigated by applying model fitting as well as isoconversional methods. Explosion delay measurement (De) was also evaluated to determine the response of this complex under the condition of rapid heating.

  13. Synthesis of Chiral Metal Complexes of Unsymmetrical Schiff Bases

    Institute of Scientific and Technical Information of China (English)


    @@ Recently, in asymmetric catalyst research the great developments of chiral Salen complexes have been made, but the report on unsymmetrical schiff bases is deficient. The unsymmetrical schiff bases complexes are an effective system in catalytically selective Olefin-epoxidations1. At the same time, unsymmetrical schiff bases was immobilized onto polymer supports for heterogenization2. The potential benefits of the catalyst include facilitation of catalyst separation from reagents, simplification of methods for catalyst recycle, and the possible adaptation of the immobilized catalyst to continuous-flow processes. A series of new unsymmetrical schiff bases was synthesized to study the relations between unsymmetry and enantioselectivity and select better catalyst. The following is the route:

  14. Water-Soluble Iron(IV)-Oxo Complexes Supported by Pentapyridine Ligands: Axial Ligand Effects on Hydrogen Atom and Oxygen Atom Transfer Reactivity. (United States)

    Chantarojsiri, Teera; Sun, Yujie; Long, Jeffrey R; Chang, Christopher J


    We report the photochemical generation and study of a family of water-soluble iron(IV)-oxo complexes supported by pentapyridine PY5Me2-X ligands (PY5Me2 = 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine; X = CF3, H, Me, or NMe2), in which the oxidative reactivity of these ferryl species correlates with the electronic properties of the axial pyridine ligand. Synthesis of a systematic series of [Fe(II)(L)(PY5Me2-X)](2+) complexes, where L = CH3CN or H2O, and characterizations by several methods, including X-ray crystallography, cyclic voltammetry, and Mössbauer spectroscopy, show that increasing the electron-donating ability of the axial pyridine ligand tracks with less positive Fe(III)/Fe(II) reduction potentials and quadrupole splitting parameters. The Fe(II) precursors are readily oxidized to their Fe(IV)-oxo counterparts using either chemical outer-sphere oxidants such as CAN (ceric ammonium nitrate) or flash-quench photochemical oxidation with [Ru(bpy)3](2+) as a photosensitizer and K2S2O8 as a quencher. The Fe(IV)-oxo complexes are capable of oxidizing the C-H bonds of alkane (4-ethylbenzenesulfonate) and alcohol (benzyl alcohol) substrates via hydrogen atom transfer (HAT) and an olefin (4-styrenesulfonate) substrate by oxygen atom transfer (OAT). The [Fe(IV)(O)(PY5Me2-X)](2+) derivatives with electron-poor axial ligands show faster rates of HAT and OAT compared to their counterparts supported by electron-rich axial donors, but the magnitudes of these differences are relatively modest.

  15. Using Simple Manipulatives to Improve Student Comprehension of a Complex Biological Process: Protein Synthesis (United States)

    Guzman, Karen; Bartlett, John


    Biological systems and living processes involve a complex interplay of biochemicals and macromolecular structures that can be challenging for undergraduate students to comprehend and, thus, misconceptions abound. Protein synthesis, or translation, is an example of a biological process for which students often hold many misconceptions. This article…

  16. Studies on solid phase synthesis,characterization and fluorescent property of the new rare earth complexes

    Directory of Open Access Journals (Sweden)

    Jianwei SHI


    Full Text Available Rare earth-β-diketone ligand complex luminescent material has stable chemical properties and excellent luminous property. Using europium oxide and (γ-NTA as raw materials, novel rare earth-β-dione complexes are synthesized by solid state coordination chemistry. The synthesis temperature and milling time are discussed for optimization. Experimental results show that the suitable reaction situation is at 50 ℃ and 20 h for solid-phase synthesis. The compositions and structures of the complexes are characterized by means of elemental analysis, UV-Vis and FTIR methods, and the phase stability of the complex is determined by using TG-DTA technique. It is proved that preparation of waterless binary rare earth complexes by the solid phase reaction method results in a higher product yield. The fluorescence spectra show that between Eu (Ⅲ and γ-NTA, there exists efficient energy transfer, and the rare earth complexes synthesis is an excellent red bright light-emitting material with excellent UV excited luminescence properties.

  17. Stabilization and enhanced reactivity of actinorhodin polyketide synthase minimal complex in polymer-nucleotide coacervate droplets. (United States)

    Crosby, John; Treadwell, Tom; Hammerton, Michelle; Vasilakis, Konstantinos; Crump, Matthew P; Williams, David S; Mann, Stephen


    Compartmentalization of the minimal complex of actinorhodin polyketide synthase in coacervate liquid droplets produces enhanced yields of shunt polyketides under conditions of low and high ionic strength.

  18. Synthesis and cytotoxic activity of metallic complexes of lawsone. (United States)

    Oramas-Royo, Sandra; Torrejón, Concepción; Cuadrado, Irene; Hernández-Molina, Rita; Hortelano, Sonsoles; Estévez-Braun, Ana; de Las Heras, Beatriz


    In the present study, a series of metallic complexes of the 1,4-naphthoquinone lawsone (2-6) were synthesized and evaluated for potential cytotoxicity in a mouse leukemic macrophagic RAW 264.7 cell line. Cell viability was determined by the MTT assay. Significant growth inhibition was observed for the copper complex (4) with an IC(50) value of 2.5 μM. This compound was selected for further evaluation of cytotoxic activity on several human cancer cells including HT-29 (human colorectal adenocarcinoma), HepG2 (human hepatocellular carcinoma) and HeLa, (human cervical adenocarcinoma cells). Significant cell viability decrease was also observed in HepG2 cells. The apoptotic potential of this complex was evaluated in these cells. Compound 4 induced apoptosis by a mechanism that involves the activation of caspases 3, 8 and 9 and modulation of apoptotic-related proteins such as Bax, Bad, and p53. These results indicate that metal complexes of lawsone derivatives, in particular compound 4, might be used for the design of new antitumoral agents. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Synthesis and Cation Complexation of Lariat Calix[4 ] crowns

    Institute of Scientific and Technical Information of China (English)

    SHI Zheng-Wei; JIN Chuan-Ming; LU Guo-Yuan


    @@ Calixcrowns carrying bridging polyethyleneoxy moieties on the lower rim, which combine calixarene and crown ether in a single molecule, are a novel class of host compounds which have attracted increasing attention because of their increased ability for selective complexation of cations and neutral molecules compared with crown ethers or cal ixarenes.

  20. Synthesis and Anion Recognition of a Novel Heterocyclic Organotin Complex

    Institute of Scientific and Technical Information of China (English)

    Li Xin ZHANG; Gui Zhi LI; Zhi Qiang LI


    A novel heterocyclic hexacoordinate organotin(IV) complex, bis(O-vanillin)-semi ethylenediamino dibenzyltin (VEDBT) was synthesized by the reaction of dibenzyltin dichloride with bis(O-vanillin)-semiethyenediamine, its structure has been characterized by spectral methods.The electrodes using VEDBT as a neutral carrier show high selectivity for salicylate anions.

  1. [Synthesis of functionalized cyanines. Fluorescence properties following complexation of cations]. (United States)

    Mazières, M R; Duprat, C; Sutra, E; Lamandé, L; Bergon, M; Bellan, J; Wolf, J G; Roques, C


    The ionophoric properties of podands containing dioxazaphosphocane moieties linked by inactive spacers were studied. To increase the detection sensibility of these compounds we introduced a cyanine as spacer. Fluorescence analysis demonstrated the interest of cyanines as active spacers since the complexation by cations as Ca2+ and Mg2+ gives an enhancement of the emission intensity.

  2. Synthesis of conjugated polymers with complex architecture for photovoltaic applications

    DEFF Research Database (Denmark)

    Kiriy, Anton; Krebs, Frederik C


    A common approach to bulk heterojunction solar cells involves a “trialand- error” approach in finding optimal kinetically unstable morphologies. An alternative approach assumes the utilization of complex polymer architectures, such as donor–acceptor block copolymers. Because of a covalent...

  3. Synthesis of Backfunctionalized Imidazolinium Salts and NHC Carbene Complexes (United States)


    minimally perturbs ligand electronics • Project was dropped for Z -selective work • Can this methodology be used for backfluorinated NHC carbene complexes...completion • Exotherm suggests ester group may affect electronics Backfunctionalized Imidazolinium Salts Mono and Difunctional CF2H 2 O N N MesMes CF2H 2 O

  4. Synthesis and characterization of some metal complexes of a Schiff ...

    African Journals Online (AJOL)

    analysis, molar conductance, magnetic susceptibility, infrared and electronic ... stops at the first step, the metal ion forming a highly stable colored complex with the ..... *Intensities in parenthesis: b-broad, vs-very strong, s-strong, m-medium, ...

  5. Copolymerization of Tris(methoxyethoxyvinyl Silane with N-Vinyl Pyrrolidone: Synthesis, Characterization, and Reactivity Relationships

    Directory of Open Access Journals (Sweden)

    Ameen Hadi Mohammed


    Full Text Available Copolymer of tris(methoxyethoxyvinyl silane (TMEVS with N-vinyl pyrrolidone (NVP was synthesized by free radical polymerization in dry benzene at 70°C using benzoyl peroxide (BPO as initiator. The copolymer was characterized by viscometer, FTIR, and 1H-NMR and its thermal properties were studied by DSC and TGA. The copolymer composition was determined by elemental analysis. The monomer reactivity ratios were calculated by linearization methods proposed by Fineman-Ross and Kelen-Tudos. The intersection method was proposed by Mayo-Lewis and nonlinear method was proposed by curve-fitting procedure. The microstructure of copolymer and sequence distribution of monomers in the copolymer were calculated by statistical method.

  6. Synthesis of benzo- and naphthoquinonyl boronic acids: exploring the Diels-Alder reactivity. (United States)

    Veguillas, Marcos; Redondo, Maria C; García, Isabel; Ribagorda, María; Carreño, M Carmen


    Substituted 2-quinonyl boronic acids have been synthesised from 1,4-dimethoxy aromatic derivatives in two steps: regiocontrolled boronation and oxidative demethylation. The study of their dienophilic behaviour evidenced that the boron substituent significantly increases the reactivity and triggers an efficient domino process in which the Diels-Alder reaction was followed by a protodeboronation or dehydroboronation, depending on the substitution on both the quinone and diene partners. The boronic acid acts as a temporary controller, opening a direct access to trans-fused meta-regiosomeric adducts when 3-methyl-substituted 2-quinonyl boronic acids react with dienes with a substituent at C-1. A particularly valuable synthetic result was obtained in the reaction between 3,6-dimethyl-2-quinonyl boronic acid and piperylene under an oxygen atmosphere; trans-fused 8a-hydroxy-2,4a,8-trimethyl tetrahydronaphthoquinone was formed directly, in excellent yield and in a highly diastereoselective manner.

  7. Synthesis, structural, spectroscopic and biological studies of Schiff base complexes (United States)

    Diab, M. A.; El-Sonbati, A. Z.; Shoair, A. F.; Eldesoky, A. M.; El-Far, N. M.


    Schiff base ligand 4-((pyridin-2- yl)methyleneamino)-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one (PDMP) and its complexes were prepared and characterized on the basis of elemental analysis, IR, mass spectra and thermogravimetric analysis. All results confirm that the complexes have 1:1 (M: PMDP) stoichiometric formula [M(PMDP)Cl2H2O ] (M = Cu(II), Co(II), Ni(II) and Mn(II)), [Cd(PMDP)Cl2] and the ligand behaves as a bi/tridentate forming five-membered chelating ring towards the metal ions, bonding through azomethine nitrogen/exocyclic carbonyl oxygen, azomethine pyridine nitrogen and exocyclic carbonyl oxygen. The shift in the band positions of the groups involved in coordination has been utilized to estimate the metal-nitrogen and/or oxygen bond lengths. The complexes of Co(II), Ni(II) and Cu(II) are paramagnetic and the magnetic as well as spectral data suggest octahedral geometry, whereas the Cd(II) complex is tetrahedral. The XRD studies show that both the ligand and its metal complexes (1 and 3) show polycrystalline with crystal structure. Molecular docking was used to predict the binding between PMDP ligand and the receptors. The corrosion inhibition of mild steel in 2 M HCl solution by PDMP was explored utilizing potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and (EFM) electrochemical frequency modulation method. Potentiodynamic polarization demonstrated that PDMP compound is mixed-type inhibitor. EIS spectra exhibit one capacitive loop and confirm the protective ability. The percentage of inhibition efficiency was found to increase with increasing the inhibitor concentration.

  8. Structural analysis of a dengue cross-reactive antibody complexed with envelope domain III reveals the molecular basis of cross-reactivity. (United States)

    Midgley, Claire M; Flanagan, Aleksandra; Tran, Hai Bac; Dejnirattisai, Wanwisa; Chawansuntati, Kriangkrai; Jumnainsong, Amonrat; Wongwiwat, Wiyada; Duangchinda, Thaneeya; Mongkolsapaya, Juthathip; Grimes, Jonathan M; Screaton, Gavin R


    Dengue virus infections are still increasing at an alarming rate in tropical and subtropical countries, underlying the need for a dengue vaccine. Although it is relatively easy to generate Ab responses to dengue virus, low avidity or low concentrations of Ab may enhance infection of FcR-bearing cells with clinical impact, posing a challenge to vaccine production. In this article, we report the characterization of a mAb, 2H12, which is cross-reactive to all four serotypes in the dengue virus group. Crystal structures of 2H12-Fab in complex with domain III of the envelope protein from three dengue serotypes have been determined. 2H12 binds to the highly conserved AB loop of domain III of the envelope protein that is poorly accessible in the mature virion. 2H12 neutralization varied between dengue serotypes and strains; in particular, dengue serotype 2 was not neutralized. Because the 2H12-binding epitope was conserved, this variation in neutralization highlights differences between dengue serotypes and suggests that significant conformational changes in the virus must take place for Ab binding. Surprisingly, 2H12 facilitated little or no enhancement of infection. These data provide a structural basis for understanding Ab neutralization and enhancement of infection, which is crucial for the development of future dengue vaccines.

  9. Synthesis of supramolecular iron (III) complexes by cluster aggregation (United States)

    Seddon, Elisa Joy


    Biologically, iron is a ubiquitous and versatile metal, found in the active sites of proteins responsible for both oxygen and electron transport. Multinuclear iron-oxo proteins are either dinuclear, or contain many iron atoms; the [Fe2O] unit occurs in hemerythrin (Hr), ribonucleotide reductase, purple acid phosphatase (POP) and methane monooxygenase (MMO), whereas ferritin (Ft) can store up to 4500 iron atoms. Iron storage and transport are essential for protecting biological organisms from free iron, since free Fe(II) ions, will react with dioxygen to form destructive organic radicals, and free Fe(III) ions form insoluble iron hydroxide aggregates under physiological conditions. The tendency of iron to form molecular aggregates in systems containing water or alcohol, together with the fact that each iron atom possesses a large number of unpaired electrons (5 for high-spin FeIII) often results in products possessing large spin ground states (S). The current record-holder for iron is a Fe19 complex, with at least 33 unpaired electrons in the ground state (S = 33/2). Hence, iron is also important in the rapidly developing field of molecular magnetic materials. For these two reasons, the preparation of iron clusters with new topologies and properties has become a major goal of many synthetic inorganic groups, including our own. In this thesis work, synthetic and spectroscopic methods of inorganic coordination chemistry were used to achieve two different goals: firstly, to synthesize dinuclear iron complexes with the use of tetradentate ligands in order to study the magnetic interactions between the two metal centers; and secondly, to identify reactions and characterize the products whereby pre-formed iron oxide clusters undergo aggregation reactions to produce higher nuclearity products. The tetradentate ligands investigated were a bis-(beta-diketone) ligand L and a bis-bpy ligand L'. The reactions involving L and Fe(III) reagents produced complexes with a triple

  10. Infant food applications of complex carbohydrates: Structure, synthesis, and function. (United States)

    Ackerman, Dorothy L; Craft, Kelly M; Townsend, Steven D


    Professional health bodies such as the World Health Organization (WHO), the American Academy of Pediatrics (AAP), and the U.S. Department of Health and Human Services (HHS) recommend breast milk as the sole source of food during the first year of life. This position recognizes human milk as being uniquely suited for infant nutrition. Nonetheless, most neonates in the West are fed alternatives by 6 months of age. Although inferior to human milk in most aspects, infant formulas are able to promote effective growth and development. However, while breast-fed infants feature a microbiota dominated by bifidobacteria, the bacterial flora of formula-fed infants is usually heterogeneous with comparatively lower levels of bifidobacteria. Thus, the objective of any infant food manufacturer is to prepare a product that results in a formula-fed infant developing a breast-fed infant-like microbiota. The goal of this focused review is to discuss the structure, synthesis, and function of carbohydrate additives that play a role in governing the composition of the infant microbiome and have other health benefits.

  11. Synthesis of Chiral Metal Complexes of Unsymmetrical Schiff Bases

    Institute of Scientific and Technical Information of China (English)

    SONG; Bo


    Recently, in asymmetric catalyst research the great developments of chiral Salen complexes have been made, but the report on unsymmetrical schiff bases is deficient. The unsymmetrical schiff bases complexes are an effective system in catalytically selective Olefin-epoxidations1. At the same time, unsymmetrical schiff bases was immobilized onto polymer supports for heterogenization2. The potential benefits of the catalyst include facilitation of catalyst separation from reagents, simplification of methods for catalyst recycle, and the possible adaptation of the immobilized catalyst to continuous-flow processes. A series of new unsymmetrical schiff bases was synthesized to study the relations between unsymmetry and enantioselectivity and select better catalyst. The following is the route:  ……

  12. Synthesis, molecular spectroscopy and thermal analysis of some cefepime complexes (United States)

    Masoud, Mamdouh S.; Ali, Alaa E.; Ghareeb, Doaa A.; Nasr, Nessma M.


    The metal complexes of cefepime with Cr (III), Mn (II), Fe (III), Co (II), Cu (II), Zn (II), Cd (II), Hg (II) and mixed metals (Fe, Ni) or (Cu, Fe) were synthesized, the suggested structures of the complexes are based on the results of the elemental analysis, infrared, UV-visible, mass and HNMR spectra, effective magnetic moment as well as the thermal analysis (DTA, TGA & DSC) and characterized by energy dispersive x-ray (EDX) and scanning electron microscopy (SEM). The results obtained suggested that cefepime reacted with metal ions as bidentate ligand through the nitrogen of the β-lactone thiozolidine ring and carboxylate ion forming a five membered ring. The kinetic thermodynamic parameters were estimated from the DTA curves.

  13. Synthesis, structure, and reactivity of electron-deficient zirconium and hafnium polyhydride complexes

    NARCIS (Netherlands)

    Visser, Cindy


    This thesis addresses the consequences of a new school choice procedure for the transition of pupils from primary education to secondary education in Amsterdam. The thesis focuses not so much on the stages in the school choice process as on the use of data that the new procedure provides for the qua

  14. Crotylsilane reagents in the synthesis of complex polyketide natural products: total synthesis of (+)-discodermolide. (United States)

    Arefolov, Alexander; Panek, James S


    An efficient, highly convergent stereocontrolled synthesis of (+)-discodermolide has been achieved with 2.1% overall yield (27 steps longest linear sequence). The absolute stereochemistry of the C1-C6 (12), C7-C14 (13), and C15-C24 (11) subunits was introduced using asymmetric crotylation methodology. Key elements of the synthesis include the use of hydrozirconation-cross-coupling methodology for the construction of C13-C14 (Z)-olefin, acetate aldol reaction to construct the C6-C7 bond and install the C7 stereocenter with high levels of 1,5-anti stereoinduction, and the use of palladium-mediated sp(2)-sp(3) cross-coupling reaction to join the advanced fragments, which assembled the carbon framework of discodermolide.




    Two new hydrogenoxalato and one malonato adduct and complex have been synthesized and studied by infrared and NMR spectroscopies. The suggested structures are discrete, the hydrogenoxalate behaving as a monodentate ligand or only involved in hydrogen bonding, the environment around the tin (IV) centre being tetrahedral or trigonal bipyramidal. The malonate anion is a monodentate ligand. In all the suggested structures, when extra hydrogen bonds are considered, supramolecular architectures are...

  16. Alkynyl triphosphine copper complexes: synthesis and photophysical studies. (United States)

    Chakkaradhari, Gomathy; Belyaev, Andrey A; Karttunen, Antti J; Sivchik, Vasily; Tunik, Sergey P; Koshevoy, Igor O


    A rigid triphosphine PPh2C6H4-PPh-C6H4PPh2 () reacted with Cu(+) and a stoichiometric amount of terminal alkyne under basic conditions to give a family of copper(i) alkynyl compounds [Cu()C[triple bond, length as m-dash]CR]. The number of terminal -C[triple bond, length as m-dash]CH groups in the starting ligand determines the nuclearity of the resulting complexes giving mono- (, R = Ph; , R = C6H4OMe; , R = C6H4NO2; , R = C6H4CF3; , R = 2-pyridyl), di- (R = -(C6H4)n-, n = 1 (), n = 2, (), n = 3 ()) and trinuclear complexes (, R = 1,3,5-(C6H4)3-C6H3; , R = 1,3,5-(C6H4-4-C2C6H4)3-C6H3). In all the complexes the Cu(i) centers are found in a distorted tetrahedral environment that is achieved by tridentate coordination of the ligand and σ-bonding to the alkynyl function. The crystal structures of , and were estimated by single crystal X-ray diffraction analysis. The (31)P, (1)H and (1)H-(1)H COSY NMR spectroscopy confirms that all the molecules remain intact in solution. The photophysical studies carried out in the solid state at 298 and 77 K revealed moderate to weak orange luminescence (Φem up to 19%), tentatively assigned to thermally activated delayed fluorescence for the mononuclear complexes. The quantum yields of emission of demonstrated strong dependence on the nature of the alkynyl ligand, the role of which in the electronic transitions was elucidated by TD-DFT computational studies.


    Directory of Open Access Journals (Sweden)



    Full Text Available Two new hydrogenoxalato and one malonato adduct and complex have been synthesized and studied by infrared and NMR spectroscopies. The suggested structures are discrete, the hydrogenoxalate behaving as a monodentate ligand or only involved in hydrogen bonding, the environment around the tin (IV centre being tetrahedral or trigonal bipyramidal. The malonate anion is a monodentate ligand. In all the suggested structures, when extra hydrogen bonds are considered, supramolecular architectures are obtained.

  18. Synthesis, Characterization and Antimicrobial Activity of Zirconium (IV) Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Shobhana; Jain, Asha; Saxena, Sanjiv [Univ. of Rajasthan, Jaipur (India)


    Heteroleptic complexes of zirconium (IV) derived from bulky Schiff base ligands containing a sulphur atom and oximes of heterocyclic β-diketones of the general formula ZrLL' (where L'H{sub 2}=RCNH(C{sub 6}H{sub 4})SC : C(OH)N(C{sub 6}H{sub 5})N : CCH{sub 3}, R=-C{sub 6}H{sub 5}, -C{sub 6}H{sub 4}Cl(p) and L'H{sub 2}=R'C : (NOH)C : C(OH)N(C{sub 6}H{sub 5})N : CCH{sub 3}, R' = -CH{sub 2}CH{sub 3}, -C{sub 6}H{sub 5}, -C{sub 6}H{sub 4}Cl (p) were prepared by the reactions of zirconium tetrachloride with disodium salts of Schiff bases (L Na{sub 2}) and oximes of heterocyclic β-diketones (L' Na{sub 2}) in 1:1:1 molar ratio in dry refluxing THF. The structures of these monomeric zirconium (IV) complexes were elucidated with the help of elemental analysis, molecular weight measurements, spectroscopic (IR, NMR and mass) studies. A distorted trigonal bipyramidal geometry may be suggested for these heteroleptic zirconium (IV) complexes. The ligands (bulky Schiff base ligands containing a sulphur atom and oximes of heterocyclic β-diketones) and their heteroleptic complexes of zirconium (IV) were screened against A. flavus, P. aeruginesa and E. coli.

  19. Synthesis of water-soluble CdSe quantum dots with various fluorescent properties and their application in immunoassay for determination of C-reactive protein. (United States)

    Gasparyan, V K


    Effects of various factors on synthesis and fluorescent properties of CdSe quantum dots were studied. It was shown that variation of pH, stabilizer and concentration of precursors brings to obtaining of quantum dots with various fluorescent properties. The nanoparticles prepared were conjugated with rabbit antibodies to C-Reactive protein and C-Reactive protein for competitive immunoassay for determination of CRP. It was shown that interaction of these dots as a result of antigen-antibody reaction brings to resonance energy transfer and these changes in fluorescence spectra correlate with concentration of CRP. This approach permits to determine CRP in range between 4-100 ng.

  20. Synthesis, characterization and cytotoxic activity of palladium (II) carbohydrate complexes

    Indian Academy of Sciences (India)

    S Bhavya Deepthi; Rajiv Trivedi; P Sujitha; C Ganesh Kumar; B Sridhar; Suresh K Bhargava


    Carbohydrate containing pyridyl triazole ligands, 5-deoxy-1,2--isopropylidene-5-(4-(2-pyridyl)-1H-1,2,3-triazole-1-yl)--D-xylofuranose (2a), 3--Benzyl-5-deoxy-1,2--isopropylidene-5-(4-(2-pyridyl)-1H-1,2,3-triazol-1-yl)--D-xylofuranose (2b), methyl-5-deoxy-2,3--isopropylidene-5-(4-(2-pyridyl)-1H-1,2,3-triazol-1-yl)--D-ribofuranoside, (2c) and 6-deoxy-1,2:3,4-di--isopropylidene-6-(4-(2-pyridyl)-1H-1,2,3-triazol-1-yl)--D-galactopyranose (2d) were prepared by the `click’ reaction of 2-ethynyl pyridine with the corresponding azides. The palladium complexes were synthesised by the reaction of pyridyl triazole ligands with [Pd(COD)Cl2] in dichloromethane. All the compounds were characterized by NMR, IR, mass and elemental analysis. Structural characterization of the ligand 2a was done by X-ray crystallography. The ligands and complexes were tested for their cytotoxic activity on different cell lines like A549 (human alveolar adenocarcinoma cells), Neuro2a (mouse neuroblastoma cells), HeLa (cervical carcinoma cancer cells), MDA-MB-231 (human breast adenocarcinoma cells) and MCF7 (human breast adenocarcinoma cells). The complexes showed considerable cytotoxicity while the ligands were non-toxic on the tested cell lines.

  1. Complex-mediated microwave-assisted synthesis of polyacrylonitrile nanoparticles

    Directory of Open Access Journals (Sweden)

    Trinath Biswal


    Full Text Available Trinath Biswal, Ramakanta Samal, Prafulla K SahooDepartment of Chemistry, Utkal University, Vani Vihar, Bhubaneswar 751004, IndiaAbstract: The polymerization of acrylonitrile (AN is efficiently, easily, and quickly achieved in the presence of trans-[Co(IIIen2Cl2]Cl complex in a domestic microwave (MW oven. MW irradiation notably promoted the polymerization reaction; this phenomenon is ascribed to the acceleration of the initiator, ammonium persulfate (APS, decomposition by microwave irradiation in the presence of [Co(IIIen2Cl2]Cl. The conversion of monomer to the polymer was mostly excellent in gram scale. Irradiation at low power and time produced more homogeneous polymers with high molecular weight and low polydispersity when compared with the polymer formed by a conventional heating method. The interaction of reacting components was monitored by UV-visible spectrometer. The average molecular weight was derived by gel permeation chromatography (GPC, viscosity methods, and sound velocity by ultrasonic interferometer. The uniform and reduced molecular size was characterized by transmission electron microscopy, the diameter of polyacrylonitrile nanoparticles (PAN being in the range 50–115 nm and 40–230 nm in microwave and conventional heating methods respectively. The surface morphology of PAN prepared by MW irradiation was characterized by scanning electron microscope (SEM. From the kinetic results, the rate of polymerization (Rp was expressed as Rp = [AN]0.63 [APS]0.57 [complex (I].0.88Keywords: microwave, complex catalyst, nanoparticle, kinetics

  2. The origin, composition, and reactivity of dissolved iron(III) complexes in coastal organic- and iron-rich sediments (United States)

    Beckler, Jordon S.; Jones, Morris E.; Taillefert, Martial


    The redox chemistry and speciation of Fe in both solid and dissolved phases were characterized in the organic- and Fe-rich sediments of the Satilla River estuary in South-East Georgia (USA) on a series of four cruises between July 2007 and January 2008. Results indicate that dissolved Fe is present in relatively high concentration in the overlying waters at the freshwater end of the estuary and flocculates along the river as the salinity increases downstream. Soluble organic-Fe(III) complexes comprise the majority of dissolved Fe (Shewanella putrefaciens strain 200, increased production of soluble organic-Fe(III) complexes, and addition of reactive Fe(III) hydroxides accelerated the non-reductive dissolution of Fe(III) (oxy)hydroxides irrespective of the presence of exogenous FeRB. These findings suggest soluble organic-Fe(III) complexes in suboxic pore waters may be produced both as intermediates during the dissimilatory reduction of Fe(III) (oxy)hydroxides by Fe(III)-reducing microorganisms and during the oxidation of organic-Fe(II) complexes by Fe(III) (oxy)hydroxides. These soluble organic-Fe(III) complexes are stable in pore waters and may flux from the sediments to the continental shelf.

  3. Electrochemical behavior and dioxygen reactivity of tripodal dinuclear copper complexes linked by unsaturated rigid spacers. (United States)

    Gomila, Antoine; Le Poul, Nicolas; Kerbaol, Jean-Michel; Cosquer, Nathalie; Triki, Smaïl; Douziech, Bénédicte; Conan, Françoise; Le Mest, Yves


    New dinucleating ligands based on two tripodal tris(2-pyridylmethyl)amine (TMPA) units linked by a series of delocalized π-electrons spacers have been synthesized. Their di-Cu(II) complexes have been prepared and structurally characterized. As compared to the corresponding monotopic complexes, these dinuclear Cu(II) complexes reveal spectroscopic and voltammetric features ascribable to weakly perturbed electronic interactions. In the case of the anthracenyl spacer, observation both in the solid and in solution suggests that the existence of intramolecular π-π stacking interactions influences the geometry of the complex and hence its electronic properties. The bis-Cu(I) complexes were prepared electrochemically. In the specific case of the complex bearing a mono-alkyne spacer, addition of dioxygen in acetonitrile leads to the slow formation of a trans-μ-1,2 peroxo Cu(2) complex which shows good stability at 268 K (t(1/2) = 240 s). Analysis of the kinetics of the peroxo formation by UV-vis spectroscopy suggests that the increased activation barrier for intramolecular binding of dioxygen is due to the rigidity of the spacer.

  4. Complex Psychological Trauma and Self-Dysregulation: A Theory Synthesis for Nursing. (United States)

    Choi, Kristen R


    Complex psychological trauma is a phenomenon resulting from severe interpersonal trauma that can negatively affect how individuals experience health care. However, few theories conceptualizing complex trauma exist, and it has received only limited attention in the nursing literature. The purpose of this theory synthesis was to organize two theories of (a) self-regulation and (b) self-dysregulation following complex psychological trauma into a single conceptual framework for use in nursing practice. This article used the theory synthesis approach described by Walker and Avant. The theory has potential to advance nursing science by helping nurses and other health professionals understand how trauma can alter self-regulatory processes and result in unique challenges in care delivery. It also has potential to prevent retraumatization of trauma survivors at the hands of health care providers.

  5. Synthesis, characterization and luminescence studies of gold(I–NHC amide complexes

    Directory of Open Access Journals (Sweden)

    Adrián Gómez-Suárez


    Full Text Available A flexible, efficient and straightforward methodology for the synthesis of N-heterocyclic carbene gold(I–amide complexes is reported. Reaction of the versatile building block [Au(OH(IPr] (1 (IPr = 1,3-bis(2,6-diisopropylphenylimidazol-2-ylidene with a series of commercially available (heteroaromatic amines leads to the synthesis of several [Au(NRR’(IPr] complexes in good yields and with water as the sole byproduct. Interestingly, these complexes present luminescence properties. UV–vis and fluorescence measurements have allowed the identification of their excitation and emission wavelengths (λmax. These studies revealed that by selecting the appropriate amine ligand the emission can be easily tuned to achieve a variety of colors, from violet to green.

  6. Asymmetric synthesis of tertiary alcohols by the use of tricarbonylchromium (O) complexes

    Energy Technology Data Exchange (ETDEWEB)

    Furtado, O.R.; Gomes Costa, M.R.; Marcelo Curto, M.J. [Instituto Nacional de Engenharia e Tecnolgia Industrial, Queluz (Portugal)] [and others


    The demand for homochiral compounds by the pharmaceutical and related industries has stimulated great interest in the development of asymmetric methodology for organic synthesis. The authors report herein the stereoselective synthesis of tertiary benzylic alcohols. These homochiral tertiary alcohols could be obtained by stereoselective addition to the carbonyl function of chiral [(aryl)Cr(CO){sub 3}] ketones. The syntheses of these ketones were performed by reaction of lithiated (arene)Cr(CO){sub 3} complexes with acyl halides or aldehydes followed by Swern oxidation of the alcohols obtained.

  7. The synthesis, characterization and reactivity of high oxidation state nickel fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Chacon, L.C. [Univ. of Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley National Lab., CA (United States). Chemical Sciences Div.


    The research described in this thesis has mainly addressed the challenge of the synthesis of thermodynamically unstable nickel fluorides, which cannot be made by traditional thermal methods. A low-temperature approach towards the synthesis of such transition metal fluorides exploits the greater thermodynamic stability of high oxidation states in anions and involves the use of anhydrous hydrogen fluoride (aHF) as a solvent. The general method consists of combining an aHF soluble starting material (e.g., K{sub 2}NiF{sub 6}) with a Lewis fluoroacid (e.g., BF{sub 3}), which precipitates a neutral polymeric solid state fluoride: 2 K{sup +} + NiF{sub 6}{sup 2{minus}} + BF{sub 3} {r_arrow} NiF{sub 4} + 2 BF{sub 4}{sup {minus}} + 2 K{sup +}. At room temperature, this reaction yields a different structural phase, with composition K{sub x}NiF{sub 3} (x {approx} 0.18). This material has a pseudo-hexagonal tungsten bronze structure (H{sub 0}-K{sub x}NiF{sub 3}), and is an ionic conductor, probably due to K{sup +} ions hosted in the lattice channels. R-NiF{sub 3} is capable of fluorinating a wide range of inorganic and organic substrates. These reactions have probably shed light on the mechanism of the Simons Electrochemical Fluorination (ECF) Process, an important industrial method of fluorinating organic compounds. It has long been speculated that NiF{sub 3} plays a role in the ECF process, which uses nickel electrodes in aHF solvent. K{sub 2}NiF{sub 6} also fluorinates organic compounds in aHF, but interestingly, yields different fluorinated products. The reduction of R-NiF{sub 3} and K{sub 2}NiF{sub 6} during fluorination reactions yields NiF{sub 2}. A method has been developed to regenerate NiF{sub 6}{sup 2{minus}} from NiF{sub 2}.

  8. The synthesis, characterization and reactivity of high oxidation state nickel fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Chacon, L.C. [Univ. of Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley National Lab., CA (United States). Chemical Sciences Div.


    The research described in this thesis has mainly addressed the challenge of the synthesis of thermodynamically unstable nickel fluorides, which cannot be made by traditional thermal methods. A low-temperature approach towards the synthesis of such transition metal fluorides exploits the greater thermodynamic stability of high oxidation states in anions and involves the use of anhydrous hydrogen fluoride (aHF) as a solvent. The general method consists of combining an aHF soluble starting material (e.g., K{sub 2}NiF{sub 6}) with a Lewis fluoroacid (e.g., BF{sub 3}), which precipitates a neutral polymeric solid state fluoride: 2 K{sup +} + NiF{sub 6}{sup 2{minus}} + BF{sub 3} {r_arrow} NiF{sub 4} + 2 BF{sub 4}{sup {minus}} + 2 K{sup +}. At room temperature, this reaction yields a different structural phase, with composition K{sub x}NiF{sub 3} (x {approx} 0.18). This material has a pseudo-hexagonal tungsten bronze structure (H{sub 0}-K{sub x}NiF{sub 3}), and is an ionic conductor, probably due to K{sup +} ions hosted in the lattice channels. R-NiF{sub 3} is capable of fluorinating a wide range of inorganic and organic substrates. These reactions have probably shed light on the mechanism of the Simons Electrochemical Fluorination (ECF) Process, an important industrial method of fluorinating organic compounds. It has long been speculated that NiF{sub 3} plays a role in the ECF process, which uses nickel electrodes in aHF solvent. K{sub 2}NiF{sub 6} also fluorinates organic compounds in aHF, but interestingly, yields different fluorinated products. The reduction of R-NiF{sub 3} and K{sub 2}NiF{sub 6} during fluorination reactions yields NiF{sub 2}. A method has been developed to regenerate NiF{sub 6}{sup 2{minus}} from NiF{sub 2}.

  9. Synthesis of novel europium complexes and their photoluminescence properties

    Institute of Scientific and Technical Information of China (English)

    SHI Linfang; LI Yanwei; CAO Huaru; GUAN Ying; MA Yongchun


    Two novel luminescent Eu(Ⅲ) complexes with the formulas (NIP)Eu(DBM)3 1 and (ENIP)Eu(DBM)3 2 (NIP=2-(naphthalen-1-yl)-1H-imidazo [4,5-f] [1,10] phenanthroline,ENIP=1-ethy1-2-(naphthalen-1-yl)-1H-imidazo [4,5-)] [1,10] phenanthroline,DBM=dibenzoylmethanato) were successfully synthesized and characterized by IR and elemental analysis.The UV-vis absorption spectra and photoluminescence properties of the complexes were investigated,and the irradiation at the absorption band between 300-400 nm of europium complexes either in solution or in the solid state led to the emission of a sharp red band at ~610 nm,a characteristic Eu3+ emission due to the transition of5D0→7F2.Furthermore,the weak emission bands around 587 and 595 nm attributed to 5D0→7F0 and 5D0→7F1 transition were also displayed in the emission spectra.These results demonstrated that the Eu(Ⅲ) ion was sensitized efficiently by the ligand and displayed photoluminescence with high intensity,narrow half-peak width,and monochromic light.The excited-state lifetimes of 1 and 2 were in the microsecond time scale,but the photoluminescence quantum yield of 2 (0.03) was two times higher than that of 1 (0.01) which should be attributed to the effect of the ethyl substituting in ENIP.


    Directory of Open Access Journals (Sweden)

    Sutopo Hadi


    Full Text Available he synthesis of two stable platinum(IV complexes containing methoxo ligand, [Pt(CH32(OCH3(OHpy2] (1 and fac-[Pt(CH32(OCH3(H2O3] (2, has been successfully performed. Complex 1 was prepared by oxidative addition reaction of cis-[Pt(CH32py2] with dry methanol, and a subsequent reaction of 1 with 70 % HClO4 in water produced the platinum complex 2. The stability of complex 2 in acidic aqueous solution was investigated and monitored with 1H and 195Pt NMR. The platinum complex 2 was found to be quite stable toward hydrolysis and no -hydride elimination was observed. Keywords: Methoxoplatinum(IV, NMR, complex stability, hydrolysis

  11. Synthesis and Structure of a New Dinuclear Uranyl Complex

    Institute of Scientific and Technical Information of China (English)


    With a heptadentate compartmental Schiff-base ligand H3L (1, 3-di[o-(salicylimino) ph-enoxyl]-2-propanol), a new binuclear diuranyl complex [(UO2)2L(OH)]?3DMF, C38H45N5O13U2, was synthesized and the crystal structure was determined by X-ray diffraction techniques. The coordination geometry are two pentagonal bipyramids. In each pentagon four kinds of U-O (phenoxido, hydroxo, alkoxo and ether oxo) bonds are discussed.

  12. Synthesis of some novel divalent transition metal complexes as antimicrobials

    Institute of Scientific and Technical Information of China (English)

    Kaushal K. Oza; Paresh N. Patel; Hasmukh S. Patel


    A novel series of transition metal complexes have been synthesized from the reaction of 5-((3-(methylthio)-5-(pyridin-4-yl)-4H-1,2,4-triazol-4-ylamino)methyl)quinolin-8-ol with transition metal salts. The structures of these compounds have been elucidated by elemental and spectral analysis. Furthermore, compounds were screened for in vitro antimicrobial activity against the representative panel of two Gram-positive and two Gram-negative bacteria and two strains of fungus. The various compounds show potent inhibitory action against test organisms.

  13. Synthesis of self-assembled Ge nano crystals employing reactive RF sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez H, A. [Universidad Autonoma del Estado de Hidalgo, Escuela Superior de Apan, Calle Ejido de Chimalpa Tlalayote s/n, Col. Chimalpa, Apan, Hidalgo (Mexico); Hernandez H, L. A. [IPN, Escuela Superior de Fisica y Matematicas, San Pedro Zacatenco, 07730 Ciudad de Mexico (Mexico); Monroy, B. M.; Santana R, G. [UNAM, Instituto de Investigaciones en Materiales, Apdo. Postal 70-360, 04510 Ciudad de Mexico (Mexico); Santoyo S, J.; Gallardo H, S. [IPN, Centro de Investigacion y de Estudios Avanzados, Departamento de Fisica, Apdo. Postal 14740, 07300 Ciudad de Mexico (Mexico); Marquez H, A. [Universidad de Guanajuato, Campus Irapuato-Salamanca, Departamento de Ingenieria Agricola, Km. 9 Carretera Irapuato-Silao, 36500 Irapuato, Guanajuato (Mexico); Mani G, P. G.; Melendez L, M. [Universidad Autonoma de Ciudad Juarez, Instituto de Ingenieria y Tecnologia, Departamento de Fisica y Matematicas, 32310 Ciudad Juarez, Chihuahua (Mexico)


    This work presents the results of a simple methodology able to control crystal size, dispersion and spatial distribution of germanium nano crystals (Ge-NCs). It takes advantage of a self-assembled process taken place during the deposit of the system SiO{sub 2}/Ge/SiO{sub 2} by reactive RF sputtering. Nanoparticles formation is controlled mainly by the roughness of the first SiO{sub 2} layer buy the ulterior interaction of the interlayer with the top layer also play a role. Structural quality of germanium nano crystals increases with roughness and the interlayer thickness. The tetragonal phase of germanium is produced and its crystallographic quality improves with interlayer thickness and oxygen partial pressure. Room temperature photoluminescence emission without a post growth thermal annealing process indicates that our methodology produces a low density of non-radiative traps. The surface topography of SiO{sub 2} reference samples was carried out by atomic force microscopy. The crystallographic properties of the samples were studied by grazing incidence X-ray diffraction at 1.5 degrees carried out in a Siemens D-5000 system employing the Cu Kα wavelength. (Author)

  14. Synthesis, Structure, and Reactivity of Anionic sp(2) -sp(3) Diboron Compounds: Readily Accessible Boryl Nucleophiles. (United States)

    Pietsch, Sabrina; Neeve, Emily C; Apperley, David C; Bertermann, Rüdiger; Mo, Fanyang; Qiu, Di; Cheung, Man Sing; Dang, Li; Wang, Jianbo; Radius, Udo; Lin, Zhenyang; Kleeberg, Christian; Marder, Todd B


    Lewis base adducts of tetra-alkoxy diboron compounds, in particular bis(pinacolato)diboron (B2 pin2 ), have been proposed as the active source of nucleophilic boryl species in metal-free borylation reactions. We report the isolation and detailed structural characterization (by solid-state and solution NMR spectroscopy and X-ray crystallography) of a series of anionic adducts of B2 pin2 with hard Lewis bases, such as alkoxides and fluoride. The study was extended to alternative Lewis bases, such as acetate, and other diboron reagents. The B(sp(2) )-B(sp(3) ) adducts exhibit two distinct boron environments in the solid-state and solution NMR spectra, except for [(4-tBuC6 H4 O)B2 pin2 ](-) , which shows rapid site exchange in solution. DFT calculations were performed to analyze the stability of the adducts with respect to dissociation. Stoichiometric reaction of the isolated adducts with two representative series of organic electrophiles-namely, aryl halides and diazonium salts-demonstrate the relative reactivities of the anionic diboron compounds as nucleophilic boryl anion sources.

  15. Stimulation of reactive oxygen species and collagen synthesis by angiotensin II in cardiac fibroblasts. (United States)

    Lijnen, Paul J; van Pelt, Jos F; Fagard, Robert H


    Superoxide anion generated by NAD(P)H-oxidase has an important role in the pathogenesis of cardiovascular diseases and scavenging superoxide anion can be considered as a reasonable therapeutic strategy. In hypertensive heart diseases there is a mutual reinforcement of reactive oxygen species (ROS) and angiotensin II (ANG II). ANG II increases the NAD(P)H-dependent superoxide anion production and the intracellular generation of ROS in cardiac fibroblasts and apocynin, a membrane NAD(P)H oxidase inhibitor, abrogates this rise. ANG II also stimulates the collagen production, the collagen I and III content and mRNA expression in cardiac fibroblasts and apocynin abolishes this induction. In this review we demonstrate that scavenging superoxide anion by tempol or EUK-8 or administration of PEG-superoxide dismutase (SOD) inhibits collagen production in cardiac fibroblasts. On the contrary increasing superoxide anion formation by inhibition of SOD stimulates collagen production. A vital role of SOD and the generated ROS can be suggested in the regulation and organization of collagen in cardiac fibroblasts. Specific pharmacological intervention with SOD mimetics can probably be an alternative approach for reducing myocardial fibrosis.

  16. Tailored functionalization of ZnO nanoparticle via reactive cyclodextrin and its bionanocomposite synthesis. (United States)

    Abdolmaleki, Amir; Mallakpour, Shadpour; Borandeh, Sedigheh


    β-cyclodextrin was grafted onto the surface of ZnO nanoparticles via efficient, simple and fast technique through nucleophilic substitution reaction of OH groups on ZnO nanoparticle surface with reactive cyclic oligosaccharide, Monochlorotriazinyl-β-cyclodextrin (MCT-β-CD). Characterization of functionalized ZnO nanoparticles were carried out by Fourier transform infrared spectra (FT-IR), elemental analysis (CHN), Thermogravimetric analysis (TGA), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The amount of MCT-β-CD bonded to the ZnO surface was determined by CHN and TGA analysis. Followed by, innovative poly(ester-amide)/ZnO bionanocomposites (PEA/ZnO BNCs) were fabricated through solution mixing method. Due to using biodegradable amino acid containing polymer, the synthesized nanocomposites are expected to classify as biologically active materials. Morphological studies of prepared BNC proved good distribution of modified ZnO in PEA matrix with nanoscale size. Good dispersion and less aggregation, indicate the effect of functionalization on preventing nanoparticles to aggregate.

  17. Metal-catalyzed cycloisomerization as a powerful tool in the synthesis of complex sesquiterpenoids. (United States)

    Stathakis, Christos I; Gkizis, Petros L; Zografos, Alexandros L


    Covering: up to 2015Sesquiterpenoids are consistently attracting the interest of the scientific community due to their promising clinical profile as therapeutic agents. Cycloisomerization of enynes and dienes is a powerful tool in the hands of organic chemists to access them. In the last 20 years the field has witnessed remarkable advances, especially by revealing the capability of platinum and gold complexes to initiate such reactions. Nowadays, cycloisomerizations continue to enrich our knowledge with atom-economical routes and impressive cascades to reach more complex molecules. The current review covers the basic mechanistic aspects of metal catalysis in cycloisomerization reactions and their progress to the synthesis of selected complex sesquiterpenoids.

  18. Simplified reactive power management strategy for complex power grids under stochastic operation and incomplete information

    DEFF Research Database (Denmark)

    Vlachogiannis, Ioannis (John)


    In the current released energy market, the large-scale complex transmission networks and the distribution ones with dispersed energy sources and "intelligent" components operate under uncertainties, stochastic and prior incomplete information. A safe and reliable operation of such complex power...... consider more stochastic aspects such as variable grid's topology. Results of the proposed strategy obtained on the networks of IEEE 30-bus and IEEE 118-bus systems demonstrate the effectiveness of the proposed strategy....

  19. Resonance raman spectra and photochemical reactivity of transition metal α-diimine complexes (United States)

    Stufkens, D. J.

    In this article the application of resonance Raman spectroscopy to the study of metal to ligand charge transfer (MLCT) transitions of α-diimine complexes is described. From these spectra information is obtained about the character of the MLCT transitions and about the properties of the excited states. It is shown how these resonance Raman spectra can be used to interpret and predict the MLCT photo-chemistry of α-diimine and imine complexes.

  20. An alternative to fully coupled reactive transport simulations for long-term prediction of chemical reactions in complex geological systems (United States)

    De Lucia, Marco; Kempka, Thomas; Kühn, Michael


    Fully-coupled reactive transport simulations involving multiphase hydrodynamics and chemical reactions in heterogeneous settings are extremely challenging from a computational point of view. This often leads to oversimplification of the investigated system: coarse spatial discretization, to keep the number of elements in the order of few thousands; simplified chemistry, disregarding many potentially important reactions. A novel approach for coupling non-reactive hydrodynamic simulations with the outcome of single batch geochemical simulations was therefore introduced to assess the potential long-term mineral trapping at the Ketzin pilot site for underground CO2 storage in Germany [1],[2]. The advantage of the coupling is the ability to use multi-million grid non-reactive hydrodynamics simulations on one side and few batch 0D geochemical simulations on the other, so that the complexity of both systems does not need to be reduced. This contribution shows the approach which was taken to validate this simplified coupling scheme. The procedure involved batch simulations of the reference geochemical model, then performing both non-reactive and fully coupled 1D and 3D reactive transport simulations and finally applying the simplified coupling scheme based on the non-reactive and geochemical batch model. The TOUGHREACT/ECO2N [3] simulator was adopted for the validation. The degree of refinement of the spatial grid and the complexity and velocity of the mineral reactions, along with a cut-off value for the minimum concentration of dissolved CO2 allowed to originate precipitates in the simplified approach were found out to be the governing parameters for the convergence of the two schemes. Systematic discrepancies between the approaches are not reducible, simply because there is no feedback between chemistry and hydrodynamics, and can reach 20 % - 30 % in unfavourable cases. However, even such discrepancy is completely acceptable, in our opinion, given the amount of

  1. Synthesis of zirconium aryloxide complexes containing pendent vinyl groups

    Energy Technology Data Exchange (ETDEWEB)

    Evans, W.J.; Ansari, M.A.; Ziller, J.W. [Univ. of California, Irvine, CA (United States). Dept. of Chemistry


    The attachment of pendent olefin groups to oxygen-ligated zirconium complexes using olefin-substituted phenols and alcohols and readily accessible zirconium reagents is described. Syntheses of three crystallographically characterizable complexes isolable in 55--90% yield are reported. Eugenol, HOC{sub 6}H{sub 3}(OMe-2)(CH{sub 2}CH{double_bond}CH{sub 2}-4)(HOAr) reacts with [Zr(O{sup i}Pr){sub 4}(HO{sup i}Pr)]{sub 2} in toluene to form [({sup i}PrO){sub 2}(ArO)Zr({mu}-O{sup i}Pr)]{sub 2}, 1. CH{sub 2}{double_bond}CHCH{sub 2}OH reacts with [Zr(NMe{sub 2}){sub 4}]{sub 2} in the presence of 2,6-dimethylphenol to form the mixed ligand salt, {l_brace}Me{sub 2}NH{sub 2}{r_brace}[(2,6-Me{sub 2}C{sub 6}H{sub 3}O){sub 3}Zr]{sub 2}({mu}-OCH{sub 2}CH{double_bond}CH{sub 2}){sub 3}{r_brace}, 2. The potassium salt derived from eugenol, KOAr, reacts with Zr(OEt){sub 4} in THF to form [K{sub 2}Zr(OAr){sub 4}(OEt)]{sub 2}(O), 3.

  2. Synthesis and structure of didysprosium complexes with a tetraketone (United States)

    Yang, Luqin; Yang, Rudong


    Two novel didysprosium (Dy 2) complexes of 1,5-bis(1'-phenyl-3'-methyl-5'-pyrazolone-4')-1,5-pentanedione (H 2L), Dy 2L 3·2H 2O and Dy 2L 3·5DMF (DMF = dimethylformamide), have been synthesized. The crystal structure of Dy 2L 3·5DMF was determined by X-ray diffraction. Crystals are triclinic, space group P1¯, with a = 16.99(1), b = 17.970(9), c = 18.28(1) Å, α = 110.36(4), β = 101.47(6), γ = 111.11(5)°, V = 4533(9) Å 3, Mr = 2017.91, Z = 2, D x = 1.48 g cm -3, μ = 17.22 cm -1, F(000) = 2056, R = 0.074 with 3804 reflections used in the refinement. In the complex, each L bonds two dysprosium atoms with its two β-diketone groups. Two DMF solvent molecules bond to each dysprosium ion. The coordination number of the two dysprosium ions is eight. The eight oxygen atoms around the dysprosium ion make up a distorted square antiprism coordination polyhedron. The resonance structures of coordinated β-diketonates are also discussed. Different lanthanide ions may stabilize the specific structure.

  3. Green synthesis of iron nanoparticles by various tea extracts: Comparative study of the reactivity (United States)

    Huang, Lanlan; Weng, Xiulan; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra


    Iron nanoparticles (Fe NPs) are often synthesized using sodium borohydride with aggregation, which is a high cost process and environmentally toxic. To address these issues, Fe NPs were synthesized using green methods based on tea extracts, including green, oolong and black teas. The best method for degrading malachite green (MG) was Fe NPs synthesized by green tea extracts because it contains a high concentration of caffeine/polyphenols which act as both reducing and capping agents in the synthesis of Fe NPs. These characteristics were confirmed by a scanning electron microscope (SEM), UV-visible (UV-vis) and specific surface area (BET). To understand the formation of Fe NPs using various tea extracts, the synthesized Fe NPs were characterized by SEM, X-ray energy-dispersive spectrometer (EDS), and X-ray diffraction (XRD). What emerged were different sizes and concentrations of Fe NPs being synthesized by tea extracts, leading to various degradations of MG. Furthermore, kinetics for the degradation of MG using these Fe NPs fitted well to the pseudo first-order reaction kinetics model with more than 20 kJ/mol activation energy, suggesting a chemically diffusion-controlled reaction. The degradation mechanism using these Fe NPs included adsorption of MG to Fe NPs, oxidation of iron, and cleaving the bond that was connected to the benzene ring.

  4. Green synthesis of iron nanoparticles by various tea extracts: comparative study of the reactivity. (United States)

    Huang, Lanlan; Weng, Xiulan; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra


    Iron nanoparticles (Fe NPs) are often synthesized using sodium borohydride with aggregation, which is a high cost process and environmentally toxic. To address these issues, Fe NPs were synthesized using green methods based on tea extracts, including green, oolong and black teas. The best method for degrading malachite green (MG) was Fe NPs synthesized by green tea extracts because it contains a high concentration of caffeine/polyphenols which act as both reducing and capping agents in the synthesis of Fe NPs. These characteristics were confirmed by a scanning electron microscope (SEM), UV-visible (UV-vis) and specific surface area (BET). To understand the formation of Fe NPs using various tea extracts, the synthesized Fe NPs were characterized by SEM, X-ray energy-dispersive spectrometer (EDS), and X-ray diffraction (XRD). What emerged were different sizes and concentrations of Fe NPs being synthesized by tea extracts, leading to various degradations of MG. Furthermore, kinetics for the degradation of MG using these Fe NPs fitted well to the pseudo first-order reaction kinetics model with more than 20 kJ/mol activation energy, suggesting a chemically diffusion-controlled reaction. The degradation mechanism using these Fe NPs included adsorption of MG to Fe NPs, oxidation of iron, and cleaving the bond that was connected to the benzene ring. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Rapid Microwave Synthesis, Characterization and Reactivity of Lithium Nitride Hydride, Li4NH

    Directory of Open Access Journals (Sweden)

    Nuria Tapia-Ruiz


    Full Text Available Lithium nitride hydride, Li4NH, was synthesised from lithium nitride and lithium hydride over minute timescales, using microwave synthesis methods in the solid state for the first time. The structure of the microwave-synthesised powders was confirmed by powder X-ray diffraction [tetragonal space group I41/a; a = 4.8864(1 Å, c = 9.9183(2 Å] and the nitride hydride reacts with moist air under ambient conditions to produce lithium hydroxide and subsequently lithium carbonate. Li4NH undergoes no dehydrogenation or decomposition [under Ar(g] below 773 K. A tetragonal–cubic phase transition, however, occurs for the compound at ca. 770 K. The new high temperature (HT phase adopts an anti-fluorite structure (space group Fm 3̅ m; a = 4.9462(3 Å with N3− and H− ions disordered on the 4a sites. Thermal treatment of Li4NH under nitrogen yields a stoichiometric mixture of lithium nitride and lithium imide (Li3N and Li2NH respectively.

  6. Guanine-06 methylation reduces the reactivity of d(GpG) towards platinum complexes. (United States)

    Struik, A F; Zuiderwijk, C T; van Boom, J H; Elding, L I; Reedijk, J


    6-methylated guanine dinucleotides were used to study the influence of hydrogen bonding on the specific binding of the antitumor drug cDDP, cis-PtCl2(NH3)2, to DNA. In this interaction, the guanine-06 site appears to be important in explaining the preference for a pGpG-N7(1),N7(2) chelate, which results from H-bridge formation with the ammine ligand of cDDP. Guanine-06 methylated dinucleotides and the nonmodified dinucleotides were reacted with [Pt(dien)Cl]+, cis-PtCl2(NH3)2, and cis-[Pt(NH3)2(H2O)2]2+ and the reaction products were characterized by 1H NMR using pH titrations. Methylation at guanine-06 clearly reduces the preference for the guanine. In competition experiments monitored by NMR and experiments using UV spectrophotometry a decreasing reactivity towards [Pt(dien)(H2O)]2+ and cis-[Pt(NH3)2(H2O)2]2+ was found, in the order of d(GpG) greater than d(GomepG) greater than d(GpGome) greater than d(GomepGome). The difference in reactivity between 5' guanine methylation and 3' guanine methylation is ascribed to differences in the H-bond formation with the backbone phosphate. The resulting reduced stacking of the bases in both modified dinucleotides, compared to the bases in d(GpG), results in a preference for the 3' guanine over 5'.

  7. Plasma synthesis of titanium nitride, carbide and carbonitride nanoparticles by means of reactive anodic arc evaporation from solid titanium

    Energy Technology Data Exchange (ETDEWEB)

    Kiesler, D., E-mail:; Bastuck, T.; Theissmann, R.; Kruis, F. E. [University of Duisburg-Essen, Institute of Technology for Nanostructures (NST) and Center for Nanointegration Duisburg-Essen (CENIDE) (Germany)


    Plasma methods using the direct evaporation of a transition metal are well suited for the cost-efficient production of ceramic nanoparticles. In this paper, we report on the development of a simple setup for the production of titanium-ceramics by reactive anodic arc evaporation and the characterization of the aerosol as well as the nanopowder. It is the first report on TiC{sub X}N{sub 1 − X} synthesis in a simple anodic arc plasma. By means of extensive variations of the gas composition, it is shown that the composition of the particles can be tuned from titanium nitride over a titanium carbonitride phase (TiC{sub X}N{sub 1 − X}) to titanium carbide as proven by XRD data. The composition of the plasma gas especially a very low concentration of hydrocarbons around 0.2 % of the total plasma gas is crucial to tune the composition and to avoid the formation of free carbon. Examination of the particles by HR-TEM shows that the material consists mostly of cubic single crystalline particles with mean sizes between 8 and 27 nm.

  8. Rare-earth metal hydrides supported by silicon-bridged boratabenzene fluorenyl ligands: synthesis, structure and reactivity. (United States)

    Wang, Chunhong; Xiang, Li; Leng, Xuebing; Chen, Yaofeng


    The reactions of rare-earth metal benzyl complexes supported by silicon-bridged boratabenzene fluorenyl ligands with PhSiH3 in toluene gave the corresponding dinuclear hydrides [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}Ln(μ-H)(THF)]2 (3-Ln; Ln = La, Nd, Gd), wherein the rare-earth metal ions are linked by both silicon-bridged boratabenzene fluorenyl ligands and hydrido ligands. The reactivity of these hydrides toward unsaturated substrates was studied. Among these, alkynides [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}Ln(μ-CCPh)]2 (4-Ln; Ln = La, Nd) were obtained via the σ-bond metathesis reaction, when 3-Ln (Ln = La, Nd) was treated with phenylacetylene. While reacting with 3-hexyne, the mono-addition product [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}Ln]2(μ-H)[μ-C(Et)[double bond, length as m-dash]C(H)Et] (5-Ln; Ln = La, Nd) was formed. Further investigations on the reactivity of 3-La displayed that benzonitrile and tert-butyl isonitrile readily inserted into the La-H bonds, affording an azomethine complex [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}La{μ-N[double bond, length as m-dash]C(H)Ph}]2 (6-La) and an N-tert-butylformimidoyl complex [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}La{μ,η(2)-C(H)[double bond, length as m-dash]N(t)Bu}]2 (7-La), respectively. The reaction with N,N'-diisopropylcarbodiimide at room temperature or at 75 °C gave a dimeric complex [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}La]2(μ-H)[μ-N((i)Pr)CHN((i)Pr)] (8-La) or a monomeric complex [Me2Si(C13H8)(C5H4BNEt2)]La[N((i)Pr)CHN((i)Pr)] (9-La), respectively.

  9. Synthesis, biological evaluation and SAR studies of novel bicyclic antitumor platinum(IV) complexes. (United States)

    Lorenzo, Julia; Delgado, Aida; Montaña, Ángel M; Mesas, Juan M; Alegre, María-Teresa; Rodríguez, María del Carmen; Avilés, Francesc-Xavier


    The present study describes the synthesis, anticancer activity and SAR studies of novel platinum(IV) complexes having 1,2-bis(aminomethyl)carbobicyclic or oxabicyclic carrier ligands, bearing chlorido and/or hydroxido ligands in axial position and chlorido or malonato ligands in equatorial position (labile ligands). These complexes were synthetized with the aim of obtaining new anticancer principles more soluble in water and therefore more bioavailable. Several substitution patterns on the platinum atom have been designed in order to evaluate their antiproliferative activity and to establish structure-activity relationship rules. The synthesis of platinum(IV) complexes with axial hydroxyl ligands on the platinum(IV) were carried out by reaction of K2Pt(OH)2Cl4 with the corresponding diamines. The complexes with axial chlorido ligands on the platinum(IV) atom were synthesized by direct reaction of diamines with K2PtCl6. Carboxylated complexes were synthesized by the substitution reaction of equatorial chlorido ligands by silver dicarboxylates. The most actives complexes were those having malonate as a labile ligand, no matter of the structure of the carrier ligand. Regarding the influence of the structure of the non-labile 1,4-diamine carrier ligand on the cytotoxicity, it was found that the complexes having the more lipophilic and symmetrical bicyclo[2.2.2]octane framework were much more active than those having an oxygen or methylene bridge.

  10. Synthesis of Self-Assembled Multifunctional Nanocomposite Catalysts with Highly Stabilized Reactivity and Magnetic Recyclability (United States)

    Yu, Xu; Cheng, Gong; Zheng, Si-Yang


    In this paper, a multifunctional Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite catalyst with highly stabilized reactivity and magnetic recyclability was synthesized by a self-assembled method. The magnetic Fe3O4 nanoparticles were coated with a thin layer of the SiO2 to obtain a negatively charged surface. Then positively charged poly(ethyleneimine) polymer (PEI) was self-assembled onto the Fe3O4@SiO2 by electrostatic interaction. Next, negatively charged glutathione capped gold nanoparticles (GSH-AuNPs) were electrostatically self-assembled onto the Fe3O4@SiO2@PEI. After that, silver was grown on the surface of the nanocomposite due to the reduction of the dopamine in the alkaline solution. An about 5 nm thick layer of polydopamine (PDA) was observed to form the Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was carefully characterized by the SEM, TEM, FT-IR, XRD and so on. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite shows a high saturation magnetization (Ms) of 48.9 emu/g, which allows it to be attracted rapidly to a magnet. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was used to catalyze the reduction of p-nitrophenol (4-NP) to p-aminophenol (4-AP) as a model system. The reaction kinetic constant k was measured to be about 0.56 min‑1 (R2 = 0.974). Furthermore, the as-prepared catalyst can be easily recovered and reused for 8 times, which didn’t show much decrease of the catalytic capability.

  11. Reactivity of a Carbon-Supported Single-Site Molybdenum Dioxo Catalyst for Biodiesel Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Mouat, Aidan R.; Lohr, Tracy L.; Wegener, Evan C.; Miller, Jeffrey T.; Delferro, Massimiliano; Stair, Peter C.; Marks, Tobin J.


    A single-site molybdenum dioxo catalyst, (Oc)2Mo(=O)2@C, was prepared via direct grafting of MoO2Cl2(dme) (dme = 1,2-dimethoxyethane) on high-surface- area activated carbon. The physicochemical and chemical properties of this catalyst were fully characterized by N2 physisorption, ICP-AES/OES, PXRD, STEM, XPS, XAS, temperature-programmed reduction with H2 (TPR-H2), and temperature-programmed NH3 desorption (TPD-NH3). The single-site nature of the Mo species is corroborated by XPS and TPR-H2 data, and it exhibits the lowest reported MoOx Tmax of reduction reported to date, suggesting a highly reactive MoVI center. (Oc)2Mo(=O)2@C catalyzes the transesterification of a variety of esters and triglycerides with ethanol, exhibiting high activity at moderate temperatures (60-90 °C) and with negligible deactivation. (Oc)2Mo(=O)2@C is resistant to water and can be recycled at least three times with no loss of activity. The transesterification reaction is determined experimentally to be first order in [ethanol] and first order in [Mo] with ΔH = 10.5(8) kcal mol-1 and ΔS = -32(2) eu. The low energy of activation is consistent with the moderate conditions needed to achieve rapid turnover. This highly active carbon-supported single-site molybdenum dioxo species is thus an efficient, robust, and lowcost catalyst with significant potential for transesterification processes.

  12. Synthesis of tantalum carbide and nitride nanoparticles using a reactive mesoporous template for electrochemical hydrogen evolution

    KAUST Repository

    Alhajri, Nawal Saad


    Tantalum carbide and nitride nanocrystals were prepared through the reaction of a tantalum precursor with mesoporous graphitic (mpg)-C 3N4. The effects of the reaction temperature, the ratio of the Ta precursor to the reactive template (mpg-C3N4), and the selection of the carrier gas (Ar, N2 and NH3) on the resultant crystal phases and structures were investigated. The produced samples were characterized using powder X-ray diffraction (XRD), CHN elemental analyses, thermogravimetric analyses (TGA), nitrogen sorption, a temperature-programmed reaction with mass spectroscopy (MS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The results indicate that the different tantalum phases with cubic structure, TaN, Ta2CN, and TaC, can be formed under a flow of nitrogen when formed at different temperatures. The Ta3N5 phase with a Ta5+ oxidation state was solely obtained at 1023 K under a flow of ammonia, which gasified the C 3N4 template and was confirmed by detecting the decomposed gaseous products via MS. Significantly, the formation of TaC, Ta2CN, and TaN can be controlled by altering the weight ratio of the C 3N4 template relative to the Ta precursor at 1573 K under a flow of nitrogen. The high C3N4/Ta precursor ratio generally resulted in high carbide content rather than a nitride one, consistent with the role of mpg-C3N4 as a carbon source. Electrochemical measurements revealed that the synthesized nanomaterials were consistently able to produce hydrogen under acidic conditions (pH 1). The obtained Tafel slope indicates that the rate-determining step is the Volmer discharge step, which is consistent with adsorbed hydrogen being weakly bound to the surface during electrocatalysis. © 2013 The Royal Society of Chemistry.

  13. Synthesis, structure, and reactivity of high oxidation state silver fluorides and related compounds

    Energy Technology Data Exchange (ETDEWEB)

    Lucier, George Michael [Univ. of California, Berkeley, CA (United States)


    This thesis has been largely concerned with defining the oxidizing power of Ag(III) and Ag(II) in anhydrous hydrogen fluoride (aHF) solution. Emphasis was on cationic species, since in a cation the electronegativity of a given oxidation state is greatest. Cationic Ag(III) solv has a short half life at ordinary temperatures, oxidizing the solvent to elemental fluorine with formation of Ag(II). Salts of such a cation have not yet been preparable, but solutions which must contain such a species have proved to be effective and powerful oxidizers. In presence of PtF6-, RuF6-, or RhF6-, Ag(III) solv effectively oxidizes the anions to release the neutral hexafluorides. Such reactivity ranks cationic Ag(III) as the most powerfully oxidizing chemical agent known as far. Unlike its trivalent relative Ag (II) solv is thermodynamically stable in acid aHF. Nevertheless, it oxidizes IrF6- to IrF6 at room temperature, placing its oxidizing potential not more than 2 eV below that of cationic Ag(III). Range of Ag2+ (MF6-2 salts attainable in aHF has been explored. An anion must be stable with respect to electron loss to Ag2+. The anion must also be a poor F- donor; otherwise, either AgF+ salts or AgF2 are generated.

  14. Multilayered and complex nanoparticle architectures through plasma synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Jonathan [Los Alamos National Laboratory; Wakeland, Stephen [UNM MECH.ENG.; Cui, Yuehua [UNM MECH.ENG.; Knapp, Angela [TOYOTA USA; Richard, Monique [TOYOTA USA; Luhrs, Claudia [UNM MECH.ENG.


    Using the Aerosol Through Plasma (ATP) method in conjunction with simple chemical techniques a variety of complex and novel nanoparticle architectures were created. A TP was used to make metal-core/carbon shell nanoparticles (ca. 50 nm diameter) of SnlCarbon and AI/Carbon. These have, respectively, potential for application as battery anode (for hybrid and electric vehicles) and high energy fuel In one example of post processing, the Sn-core/carbon-shell material is treated in acidic solution and yields a true nano-sized hollow carbon shell. These shells have potential application as catalyst supports, gas storage, a neutral buoyancy material for applications as varied as proppants, and slow release capsules for pharmaceutical or agricultural applications. A different set of post-A-T-P processes were used to make three layer nanoparticles with a metal core, graphite inner shell and ceramic outer shell. This method extends the range of achievable nanoparticles architectures, hence enabling new applications.

  15. Synthesis, characterization, and anticancer activity of ruthenium-pyrazole complexes. (United States)

    David, Solene; Perkins, Richard S; Fronczek, Frank R; Kasiri, Sahba; Mandal, Subhrangsu S; Srivastava, Radhey S


    A series of new water soluble Ru(III) pyrazole complexes mer-[RuCl(3)(DMSO-S)(pyz)(2)] 1, mer-[RuCl(3)(DMSO-S)(DMSO-O)(pyz)] 2, mer-[RuCl(3)(bpy)(dmpyz)] 3, and mer-[RuCl(3)(DMSO-S)(dmpyz)(2)] 4 (pyz=pyrazole; dmpyz=3,5-dimethylpyrazole, bpy=2,2'-bipyridine) have been synthesized and characterized by use of a combination of spectroscopy (IR and UV-visible), X-ray diffraction, and cyclic voltammetry. The molecular X-ray structure of all reported compounds (1-4) revealed distorted octahedral coordination around ruthenium. The cytotoxicity assay on human breast cancer cells (MCF7) demonstrated that compounds 1 and 4 affect cell viability, whereas compounds 2 and 3 do not show appreciable activity. The IC(50) values for 1 and 4 lie within the range of 71-32μM in MCF7 cells.

  16. Synthesis of ferrocene-labeled steroids via copper-catalyzed azide-alkyne cycloaddition. Reactivity difference between 2β-, 6β- and 16β-azido-androstanes. (United States)

    Fehér, Klaudia; Balogh, János; Csók, Zsolt; Kégl, Tamás; Kollár, László; Skoda-Földes, Rita


    Copper-catalyzed cycloaddition of steroidal azides and ferrocenyl-alkynes were found to be an efficient methodology for the synthesis of ferrocene-labeled steroids. At the same time, a great difference between the reactivity of 2β- or 16β-azido-androstanes and a sterically hindered 6β-azido steroid toward both ferrocenyl-alkynes and simple alkynes, such as phenylacetylene, 1-octyne, propargyl acetate and methyl propiolate, was observed.

  17. Synthesis and reactivity of 4,4-Dialkoxy-BODIPYs: an experimental and computational study. (United States)

    Nguyen, Alex L; Bobadova-Parvanova, Petia; Hopfinger, Melissa; Fronczek, Frank R; Smith, Kevin M; Vicente, M Graça H


    A series of boron-disubstituted O-BODIPYs were synthesized, and their structures and spectroscopic properties were investigated using both computational and experimental methods. Three methods were investigated for the preparation of 4,4-dimethoxy-BODIPYs bearing electron-donating or electron-withdrawing 8-aryl groups: method A employs refluxing in the presence of NaOMe/MeOH, method B uses AlCl3 in refluxing dichloromethane followed by addition of methanol as nucleophile, and method C involves activation of the BODIPYs using TMSOTf in refluxing toluene followed by addition of methanol. The yields obtained depend on the method used and the structure of the starting BODIPYs; for example, 1a and 3a were most efficiently prepared using method C (98 and 70%, respectively), while 2a was best prepared by method A (50%). Methods B and C were employed for the synthesis of seven new 4,4-dialkoxy-BODIPYs. 4,4-Dipropargyloxy-BODIPY 1e reacted under Cu(I)-catalyzed alkyne-azide Huisgen cycloaddition conditions to produce 4,4-bis(1,2,3-triazole)-BODIPY 4 in 78% yield. The substitution of the fluorides for alkoxy groups on the BODIPYs had no significant effect on the absorption and emission wavelengths but altered their fluorescence quantum yields. Among this series of dialkoxy-BODIPYs, the 4,4-dipropargyloxy 1e and its corresponding bis(1,2,3-triazole) 4 show the largest quantum yields in toluene and THF, respectively.

  18. Redox-inactive metal ions promoted the catalytic reactivity of non-heme manganese complexes towards oxygen atom transfer. (United States)

    Choe, Cholho; Yang, Ling; Lv, Zhanao; Mo, Wanling; Chen, Zhuqi; Li, Guangxin; Yin, Guochuan


    Redox-inactive metal ions can modulate the reactivity of redox-active metal ions in a variety of biological and chemical oxidations. Many synthetic models have been developed to help address the elusive roles of these redox-inactive metal ions. Using a non-heme manganese(II) complex as the model, the influence of redox-inactive metal ions as a Lewis acid on its catalytic efficiency in oxygen atom transfer was investigated. In the absence of redox-inactive metal ions, the manganese(II) catalyst is very sluggish, for example, in cyclooctene epoxidation, providing only 9.9% conversion with 4.1% yield of epoxide. However, addition of 2 equiv. of Al(3+) to the manganese(II) catalyst sharply improves the epoxidation, providing up to 97.8% conversion with 91.4% yield of epoxide. EPR studies of the manganese(II) catalyst in the presence of an oxidant reveal a 16-line hyperfine structure centered at g = 2.0, clearly indicating the formation of a mixed valent di-μ-oxo-bridged diamond core, Mn(III)-(μ-O)2-Mn(IV). The presence of a Lewis acid like Al(3+) causes the dissociation of this diamond Mn(III)-(μ-O)2-Mn(IV) core to form monomeric manganese(iv) species which is responsible for improved epoxidation efficiency. This promotional effect has also been observed in other manganese complexes bearing various non-heme ligands. The findings presented here have provided a promising strategy to explore the catalytic reactivity of some di-μ-oxo-bridged complexes by adding non-redox metal ions to in situ dissociate those dimeric cores and may also provide clues to understand the mechanism of methane monooxygenase which has a similar diiron diamond core as the intermediate.

  19. Assessment of impaired vascular reactivity in a rat model of diabetic nephropathy: effect of nitric oxide synthesis inhibition on intrarenal diffusion and oxygenation measured by magnetic resonance imaging. (United States)

    Hueper, Katja; Hartung, Dagmar; Gutberlet, Marcel; Gueler, Faikah; Sann, Holger; Husen, Bettina; Wacker, Frank; Reiche, Dania


    Diabetes is associated with impaired vascular reactivity and the development of diabetic nephropathy. In a rat model of streptozotocin-induced diabetic nephropathy, the effects of systemic nitric oxide (NO) synthesis inhibition on intrarenal diffusion and oxygenation were determined by noninvasive magnetic resonance diffusion tensor imaging and blood O2 level-dependent (BOLD) imaging, respectively. Eight weeks after the induction of diabetes, 21 rats [n = 7 rats each in the untreated control group, diabetes mellitus (DM) group, and DM with uninephrectomy (DM UNX) group] were examined by MRI. Diffusion tensor imaging and BOLD sequences were acquired before and after NO synthesis inhibition with N-nitro-L-arginine methyl ester (L-NAME). In the same rats, mean arterial pressure and vascular conductance were determined with and without the influence of L-NAME. In control animals, NO synthesis inhibition was associated with a significant increase of mean arterial pressure of 33.8 ± 4.3 mmHg (P animals. Similarly, L-NAME challenge induced a significant reduction of renal transverse relaxation time (T2*) at MRI in control animals, indicating reduced renal oxygenation after L-NAME injection compared with baseline. DM UNX animals did not show a significant T2* reduction after NO synthesis inhibition in the renal cortex and attenuated T2* reduction in the outer medulla. MRI parameters of tissue diffusion were not affected by L-NAME in all groups. In conclusion, BOLD imaging proved valuable to noninvasively measure renal vascular reactivity upon NO synthesis inhibition in control animals and to detect impaired vascular reactivity in animals with diabetic nephropathy.

  20. Synthesis, structural characterization, and reactivity studies of 5-CF3SO3-B10H13. (United States)

    Berkeley, Emily R; Ewing, William C; Carroll, Patrick J; Sneddon, Larry G


    In contrast to previous reactions carried out in cyclopentane solvent at room temperature that produced 6-TfO-B10H13 (TfO = CF3SO3), the reaction of closo-B10H10(2-) with a large excess of trifluoromethanesulfonic acid in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate (bmimOTf) gave exclusively the previously unknown 5-TfO-B10H13 isomer. Experimental and computational studies demonstrated that the difference in the products of the two reactions is a result of 6-TfO-B10H13 isomerizing to 5-TfO-B10H13 above room temperature in bmimOTf solutions. Reactivity studies showed that 5-TfO-B10H13: (1) is deprotonated by reaction with 1,8-bis(dimethylamino)naphthalene to form the 5-TfO-B10H12(1-) anion; (2) reacts with alcohols to produce 6-RO-B10H13 boryl ethers (R = Me and 4-CH3O-C6H4); (3) undergoes olefin-hydroboration reactions to form 5-TfO-6,9-R2-B10H11 derivatives; and (4) forms a 5-TfO-6,9-(Me2S)2-B10H11 adduct at its Lewis acidic 6,9-borons upon reaction with dimethylsulfide. The 5-TfO-6,9-(Me2S)2-B10H11 adduct was also found to undergo alkyne-insertion reactions to form a range of previously unreported triflate-substituted 4-TfO-ortho-carboranes (1-R-4-TfO-1,2-C2B10H10) and reactions with triethylamine or ammonia to form the first TfO-substituted decaborate [R3NH(+)]2[2-TfO-B10H9(2-)], and [R3NH(+)]2[1-TfO-B10H9(2-)] (R = H, Et) salts.

  1. Reactivities of d~0 transition metal complexes toward oxygen:Synthetic and mechanistic studies

    Institute of Scientific and Technical Information of China (English)

    CHEN ShuJian; ZHANG XinHao; LIN ZhenYang; WU YunDong; XUE ZiLing


    Transition metals such as Fe in porphyrin complexes are known to bind or react with O_2,and such reactions are critical to many biological functions and catalytic oxidation using O_2.The transition metals in these reactions often contain valence d electrons,and oxidation of metals is an important step.In recent years,reactions of O_2 with d~0 transition metal complexes such as Hf(NR_2)_4 (R=alkyl) have been used to make metal oxide thin films as insulating gate materials in new microelectronic devices.This feature article discusses our recent studies of such reactions and the formation of TiO_2 thin films.In contrast to the reactions of many d~n complexes where metals are often oxidized,reactions of d~0 complexes such as Hf(Nme_2)_4 and Ta(Nme_2)_4(SiR_3) with O_2 usually lead to the oxidation of ligands,forming,e.g.,-ONMe_2 and-OSiR_3 from-Nme_2 and-SiR_3 ligands,respectively.Mechanistic and theoretical studies of these reactions have revealed pathways in the formation of the metal oxide thin films as microelectronic materials.

  2. Facile P-C/C-H Bond-Cleavage Reactivity of Nickel Bis(diphosphine) Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shaoguang [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Li, Haixia [Texas A & M Univ., College Station, TX (United States). Dept. of Chemistry; Appel, Aaron M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hall, Michael B. [Texas A & M Univ., College Station, TX (United States). Dept. of Chemistry; Bullock, R. Morris [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)


    Unusual cleavage of P-C and C-H bonds of the P2N2 ligand in heteroleptic [Ni(P2N2)(diphosphine)]2+ complexes results in the formation of an iminium formyl nickelate featuring a C,P,P-tridentate coordination mode.

  3. Reactivities of d~0 transition metal complexes toward oxygen:Synthetic and mechanistic studies

    Institute of Scientific and Technical Information of China (English)


    Transition metals such as Fe in porphyrin complexes are known to bind or react with O2,and such reactions are critical to many biological functions and catalytic oxidation using O2.The transition metals in these reactions often contain valence d electrons,and oxidation of metals is an important step.In recent years,reactions of O2 with d0 transition metal complexes such as Hf(NR2)4(R=alkyl) have been used to make metal oxide thin films as insulating gate materials in new microelectronic devices.This feature article discusses our recent studies of such reactions and the formation of TiO2 thin films.In contrast to the reactions of many dn complexes where metals are often oxidized,reactions of d0 complexes such as Hf(NMe2)4 and Ta(NMe2)4(SiR3) with O2 usually lead to the oxidation of ligands,forming,e.g.,-ONMe2 and -OSiR3 from-NMe2 and-SiR3 ligands,respectively.Mechanistic and theoretical studies of these reactions have revealed pathways in the formation of the metal oxide thin films as microelectronic materials.

  4. Synthesis, characterization, and structure of reduced tungsten chalcogenide cluster complexes

    Energy Technology Data Exchange (ETDEWEB)

    Xiaobing, Xie


    Over the previous twenty years, ternary molybdenum chalcogenides of the general formula M{sub x}Mo{sub 6}Y{sub 8} (M = ternary metal cation; Y = chalcogenide), known as Chevrel phases, have been extensively studied. Many of these compounds have been found to have superconductivity, catalytic activity and ionic conductivity. The rich chemistry of the Chevrel phases raises considerable interest in finding the tungsten analogues of these phases. However, no such analogue has ever been synthesized, although the Chevrel phases are usually prepared directly from elements at high temperatures above 1000{degrees}C. The absence of the tungsten analogues may be caused by their thermodynamic instability at such high temperatures. Thus it might be necessary to avoid high-temperature synthetic procedures in order to establish the ternary and binary tungsten chalcogenides. A major focus of the McCarley research group has been on the preparation of M{sub 6}Y{sub 8}L{sub 6} (M = Mo, W; Y = S, Se, Te) cluster complexes as low temperature pathways to the Chevrel phases.

  5. Palladium(Ⅱ)-dppe-arylazoimidazole Complexes: Synthesis and Spectroscopic Charecterization

    Institute of Scientific and Technical Information of China (English)

    PRITHWIRA Byabartta


    Reaction of [Pd(dppe)Cl2/Br2] with AgOTf in a dichloromethane medium followed by ligand addition led to [Pd(dppe)(OSO2CF3)2] and then [Pd(dppe)(RaaiR')](OSO2CF3)2 [RaaiR'-p-R-C6H4-NN-C3H2-NN-1-R',(1-3),abbreviated as a N,N'-chelator,where N(imidazole)and N(azo)are represented by N and N',respectively;R=H(a),Me(b),Cl(c)and R'=Me(1),CH2CH3(2),CH2Ph(3),OSO2CF3 is the triflate anion,dppe=1,2-bis-(diphenylphosphinoethane)].31p NMR confirmed that due to the two phosphorus atom interaction in the azoimine symmetrical environment one sharp peak was formed.The 1H NMR spectral measurements suggest that azo-imine links with lot of phenyl protons in the aromatic region.13C NMR spectrum,1H-1H COSY and 1H-13C HMQC spec-trum assign the solution structure and stereo-retentive conformation in each complex.

  6. Synthesis and Crystal Structure of a New Mononuclear Copper Complex

    Institute of Scientific and Technical Information of China (English)


    A new kind of Cu (Ⅱ) complex [Cu(tpmb)2Cl2]@CH3OH@H2O (tpmb = 1,3,5-tri(2- pyrimidinyl)sulfanylmethyl-2,4,6-trimethylbenzene) was synthesized, and its structure has been determined by X-ray single-crystal diffraction. It crystallizes in the triclinic, space group P ī with a = 8.8397(2), b = 13.327(3), c = 13.926(3) (A), ( = 63.27(3), ( = 86.96(3), ( = 80.68(3)°, V = 1445.6(5) (A)3, C49H51Cl2CuN12O2S6, Mr = 1166.82, Z = 1, F(000) = 604, Dc = 1.340 g/cm3, μ = 0.735 mm-1, R = 0.0545 and wR = 0.1575 for 4521 observed reflections (I > 2σ(I)). X-ray analysis reveals that the Cu (Ⅱ) ion is coordinated by two Cl- anions and two nitrogen atoms from different pyrimidine groups, forming a square structure.

  7. Synthesis of nanosilver on polyamide fabric using silver/ammonia complex

    Energy Technology Data Exchange (ETDEWEB)

    Montazer, Majid, E-mail: [Textile Department, Functional Fibrous Structures and Environmental Enhancement (FFSEE), Amirkabir University of Technology, Hafez Avenue, Tehran (Iran, Islamic Republic of); Shamei, Ali; Alimohammadi, Farbod [Young Researchers Club, Tehran South Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)


    In this paper, a novel synthesis method for nanosilver has been introduced on or within the polymeric chains of polyamide 6 fabric by using silver/ammonia complex [Ag(NH{sub 3}){sub 2}]{sup +}. The silver complex was reduced directly by functional groups of polyamide chains without using any additional chemical reducing agents. The polyamide fabric was also stabilized with formation of new linkages between the polymeric chains of the nylon fabric through silver nanoparticle synthesis. The presence of nanosilver on the fabric was confirmed by UV–vis spectra, EDX patterns and XRD patterns. In addition, X-ray photoelectron spectroscopy (XPS) was utilized to identify the chemical state of silver in a range of silver oxide and silver metal. The SEM images confirmed the presence of nanosilver on the polyamide within the size of 20 and 150 nm. Excellent antibacterial properties were achieved with the treated fabrics against Staphylococcus aureus and Escherichia coli. Further, the antibacterial properties of the polyamide fabric treated with 35 mg/L silver/ammonia were durable against washing as they only decreased to 98.6% after 20 washes. In addition, some other properties of the treated fabrics including color changes, dimensional stability, water droplet adsorption, and reflectance spectrum are reported and thoroughly discussed. - Highlights: • Novel in situ synthesis of nanosilver on polyamide 6 • Synthesis of nanosilver without using external stabilizing and reducing agent • Synthesis of nanosilver particles within molecular chains of polyamide 6 • Producing antibacterial polyamide 6 using 35 mg/L Ag/ammonia complex • Obtaining durable antibacterial properties on polyamide 6 by this method.

  8. Bridging complexes of rare earth and cobalt cluster as catalyst precursors for Fischer-Tropsch synthesis

    Institute of Scientific and Technical Information of China (English)

    ZENG Shanghong; DU Dongping; BAI Fenghua; SU Haiquan


    Three new bridging complexes of rare earth and cobalt cluster were synthesized and characterized via ICP, IR and TG techniques.The structure of the complexes was speculated as: two rare earth atoms were bridged with four CF3COO-, and rare earth atoms were coordinated with cobalt carbonyl clusters to form a steady structure. Application of the complexes as the catalyst precursors was explored for Fischer-Tropsch synthesis. The study showed that the bridging complexes of rare earth and cobalt cluster had large molecular size and were difficult to enter pore path of γ-Al2O3, so they were dispersed on the surface of γ-A12O3 support. In addition, the performance of Co(Ce)/γ-Al2O3 was the best among the catalysts with complex as precursor and maintained 77.7% CO conversion at 220 ℃ for 80 operation hours.

  9. Metal complexes of Proline-Azo Dyes, Synthesis, Characterization, Dying Performance and Antibacterial Activity Studies

    Directory of Open Access Journals (Sweden)

    Alya Khider Abbas


    Full Text Available The synthesis, structural spectroscopic properties of 4-(2-benzimidazolylazoproline (BMP and its complexes derived from [Cu(II, Ag(I and Au(III] salts were done. The mode of bonding for the complexes were accomplished based on elemental analysis, FTIR, UV-Vis and HNMR spectroscopy, magnetic measurement and molar conductivity. It has been found that the ligand (BMP behaves as N,N-neutral bidentate which was forming chelates with molar ratio (1:2 (M:L stoichiometry for [Cu(II and Ag(I] while Au(III complex form molar ratio (1:1 at optimum concentration and pH as well as (λmax. The stability constant and Gibbs free energy for the prepared complexes are evaluated by spectroscopic methods. The prepared ligand (BMP in comparison to its metal complexes, were screened for their antibacterial activity against two bacterial species, Escherichia Coli and Staphylococcus. Dying performance was also studied.

  10. Synthesis and spectroscopic characterization of fluorescent solid rare earth complexes with hydroxamic acids

    Institute of Scientific and Technical Information of China (English)


    The complexes RE2(DHYA)3 .nH2O in the title bar were synthesized through some reactions oftrivalent rareearth ions. In the process of synthesis, dihydroxamic acids were taken as ligands while the alcohol was taken as a solvent.The ligands included adipylhydroxamic acid (ADHA), p-phthalichydroxamic acid (PPHA), oxalohydroxamic acid (OXHA), butadihydroxamic acid (BDHA), o-phthalichydroxamic acid (OPHA), benzoylhydroxamic acid (BHA), etc.Measured at 25 ℃, the molar conductances in various modes are 13.00-21.05 S. cm2. mol-1, which shows that rare-earth complexes are nonelectrolytes and the hydroxamino groups of the complexes have taken part in bonding. Infrared spectra, ultraviolet spectra, nuclear magnetic resonance (1HNMR) spectra, and fluorescence spectra were used to investigate the complexes. Experiments have proved that the complexes of Eu3+ and Tb3+ with aromatic hydroxamic acids have good fluorescent characteristics.

  11. Single-molecule synthesis and characterization of metal-ligand complexes by low-temperature STM. (United States)

    Liljeroth, Peter; Swart, Ingmar; Paavilainen, Sami; Repp, Jascha; Meyer, Gerhard


    We present scanning tunneling microscopy (STM)-based single-molecule synthesis of linear metal-ligand complexes starting from individual metal atoms (iron or nickel) and organic molecules (9,10-dicyanoanthracene) deposited on an ultrathin insulating film. We directly visualize the frontier molecular orbitals by STM orbital imaging, from which, in conjunction with detailed density functional theory calculations, the electronic structure of the complexes is inferred. Our studies show how the order of the molecular orbitals and the spin-state of the complex can be engineered through the choice of the metal atom. The high-spin iron complex has a singly occupied delocalized orbital with a large spin-splitting that points to the use of these engineered complexes as modular building blocks in molecular spintronics.

  12. Microwave-Assisted Routes for the Synthesis of Complex Functional Oxides

    Directory of Open Access Journals (Sweden)

    Jesús Prado-Gonjal


    Full Text Available The synthesis of complex functional inorganic materials, such as oxides, can be successfully performed by using microwave irradiation as the source of heat. To achieve this, different routes and set-ups can be used: microwave-assisted synthesis may proceed in the solid state or in solution, aqueous or not, and the set ups may be as simple and accessible as domestic oven or quite sophisticated laboratory equipment. An obvious advantage of this innovative methodology is the considerable reduction in time—minutes rather than hours or days—and, as a consequence, energy saving. No less important is the fact that the particle growth is inhibited and the broad variety of different microwave or microwave-assisted synthesis techniques opens up opportunities for the preparation of inorganic nanoparticles and nanostructures. In this work, various microwave synthesis techniques have been employed: solid-state microwaves, single-mode microwaves using a TE10p cavity and microwave-assisted hydrothermal synthesis. Relevant examples are presented and discussed.

  13. Synthesis and characterization of nickel complexes derived from Schiff-Bases

    Directory of Open Access Journals (Sweden)

    Mirian Y. Matsumoto


    Full Text Available Aromatic Schiff-Bases constitute a large class of organic compounds containing the imine group (C=N [1-3]. 2-hydroxybenzaldehyde (salicylaldehyde which has been frequently used for the synthesis of aromatic Schiff-Bases, it has many biological applications, such as analgesics, anti-inflammatory, antibacterial, antiviral and bactericidal activities [4-6]. From above, this project proposed the synthesis of three Schiff bases derived from salicylaldehyde prepared by condensation between salicylaldehyde with different p-substituted anilines (H, NO2 and MeO. Schiff-Bases synthesized were used as starting compound for the synthesis of nickel complexes. The synthesis of nickel complexes were carried out by adding of alcoholic solution of ligands (2 eq. in aqueous solution of NiCl2.6 H2O (1 eq. contain KOH (1eq. 3 hours. After thisMatsumoto et al. time, the reaction was kept to r.t. to obtain a precipitates. The precipitates were filtered under vacuum and they were characterized by GC-MS, FT-IR and UV-Vis

  14. Specific activation of human interleukin-5 depends on de novo synthesis of an AP-1 complex. (United States)

    Schwenger, Gretchen T F; Kok, Chee Choy; Arthaningtyas, Estri; Thomas, Marc A; Sanderson, Colin J; Mordvinov, Viatcheslav A


    It is clear from the biology of eosinophilia that a specific regulatory mechanism must exist. Because interleukin-5 (IL5) is the key regulatory cytokine, it follows that a gene-specific control of IL5 expression must exist that differs even from closely related cytokines such as IL4. Two features of IL5 induction make it unique compared with other cytokines; first, induction by cyclic adenosine monophosphate (cAMP), which inhibits other T-cell-derived cytokines, and second, sensitivity to protein synthesis inhibitors, which have no effect on other cytokines. This study has utilized the activation of different transcription factors by different stimuli in a human T-cell line to study the role of conserved lymphokine element 0 (CLE0) in the specific induction of IL5. In unstimulated cells the ubiquitous Oct-1 binds to CLE0. Stimulation induces de novo synthesis of the AP-1 members JunD and Fra-2, which bind to CLE0. The amount of IL5 produced correlates with the production of the AP-1 complex, suggesting a key role in IL5 expression. The formation of the AP-1 complex is essential, but the rate-limiting step is the synthesis of AP-1, especially Fra-2. This provides an explanation for the sensitivity of IL5 to protein synthesis inhibitors and a mechanism for the specific induction of IL5 compared with other cytokines.

  15. Pan-African Paleostresses and Reactivation of the Eburnean Basement Complex in Southeast Ghana (West Africa

    Directory of Open Access Journals (Sweden)

    Mahaman Sani Tairou


    Full Text Available This faulting tectonics analysis concerns the southernmost segment of the Dahomeyide Orogen and the West-African craton eastern margin in southeast Ghana. The analysis of strike-slip faults in the frontal units of the Dahomeyide Belt indicates that four distinct compressive events (NE-SW, ENE-WSW to E-W, ESE-WNW to SE-NW and SE-NW to SSE-NNW originated the juxtaposition of the Pan-African Mobile Zone and the West-African craton. These paleostress systems define a clockwise rotation of the compressional axis during the structuring of the Dahomeyide Orogen (650–550 Ma. The SE-NW and SSE-NNW to N-S compressional axes in the cratonic domain and its cover (Volta Basin suggest that the reactivation of the eastern edge of the West African craton is coeval with the last stages of the Pan-African tectogenesis in southeast Ghana. An extensional episode expressed as late normal faulting is also recorded in this study. This E-W to SE-NW extension, which is particular to the southernmost part of the Dahomeyide Belt, appears to be post-Pan-African. This extension probably contributed to the formation of a major Jurassic rifting zone that originated the Central Atlantic and the Benue Trough.

  16. Synthesis, characterization and biological profile of metal and azo-metal complexes of embelin

    Directory of Open Access Journals (Sweden)

    R. Aravindhan


    Full Text Available The present study emphasizes synthesis and bioprofiling of embelin, embelin-metal (EM and embelin-azo-metal (EAM complexes in detail. EM complexes were prepared using pure embelin and d-block transition elements, namely Mn, Fe, Co, Ni, Cu, and Zn. Similarly, EAM complexes were synthesized using phenyl azo-embelin with the said transition metals. Embelin, EM, and EAM complexes were subjected to ultra violet visible spectroscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance, electrospray ionization mass spectrometry, thermogravimetric analysis, carbon hydrogen nitrogen sulfur analysis. With regard to bioprofiling, the test complexes were studied for the antioxidant and antimicrobial activities. Results revealed that the prepared EM and EAM complexes form octahedral complexes with embelin with the yield in the range of 45–75%. All the instrumental analyses authenticate the interaction of metals with bidentate embelin through its enolic and quinonic oxygen atoms as [M(Emb2(H2O2]H2O and [M(Emb-Azo2(H2O2]. The antioxidant profile studies suggested that upon complexation with metals, the free radical scavenging activity of embelin reduced significantly. But, with regard to antimicrobial activity, cobalt and nickel embelin complexes displayed>80% growth inhibition in comparison with embelin alone. The hemolytic activity studies suggested that both embelin and the metal complexes are non-hemolytic. The reason for the reduction in antioxidant and an increase in antimicrobial activities were discussed in detail.

  17. Green synthesis of ZnO nanoparticles via complex formation by using Curcuma longa extract (United States)

    Fatimah, Is; Yudha, Septian P.; Mutiara, Nur Afisa Lintang


    Synthesis of ZnO nanoparticles(NPs) were conducted via Zn(II) complex formation by using Curcuma longa extract as template. Curcuma longa extract has the ability to form zinc ions complex with curcumin as ligating agent. Study on synthesis was conducted by monitoring thermal degradation of the material. Successful formation of zinc oxide nanoparticles was confirmed by employing x-ray diffraction, surface area analysis and transmission electron microscopy(TEM) studies. From the XRD analysis it is denoted that ZnO in hexagonal wurtzite phase was formed and particle size was varied as varied temperature. The data are also confirmed by TEM analysis which shows the particle sie at the range 20-80nm. The NPs exhibited excelent photocatalytic activity for methylene blue degradation and also significant antibacterial activity for Eschericia coli. The activity in methylene blue degradation was also confirmed from fast chemical oxygen demand (COD) reduction.

  18. Green synthesis of ZnO nanoparticles via complex formation by using Curcuma longa extract

    Energy Technology Data Exchange (ETDEWEB)

    Fatimah, Is, E-mail:; Yudha, Septian P.; Mutiara, Nur Afisa Lintang [Chemistry Department, Islamic University of Indonesia Kampus Terpadu UII, Jl. Kaliurang Km 14, Sleman, Yogyakarta (Indonesia)


    Synthesis of ZnO nanoparticles(NPs) were conducted via Zn(II) complex formation by using Curcuma longa extract as template. Curcuma longa extract has the ability to form zinc ions complex with curcumin as ligating agent. Study on synthesis was conducted by monitoring thermal degradation of the material. Successful formation of zinc oxide nanoparticles was confirmed by employing x-ray diffraction, surface area analysis and transmission electron microscopy(TEM) studies. From the XRD analysis it is denoted that ZnO in hexagonal wurtzite phase was formed and particle size was varied as varied temperature. The data are also confirmed by TEM analysis which shows the particle sie at the range 20-80nm. The NPs exhibited excelent photocatalytic activity for methylene blue degradation and also significant antibacterial activity for Eschericia coli. The activity in methylene blue degradation was also confirmed from fast chemical oxygen demand (COD) reduction.

  19. Complex generalized minimal residual algorithm for iterative solution of quantum-mechanical reactive scattering equations (United States)

    Chatfield, David C.; Reeves, Melissa S.; Truhlar, Donald G.; Duneczky, Csilla; Schwenke, David W.


    Complex dense matrices corresponding to the D + H2 and O + HD reactions were solved using a complex generalized minimal residual (GMRes) algorithm described by Saad and Schultz (1986) and Saad (1990). To provide a test case with a different structure, the H + H2 system was also considered. It is shown that the computational effort for solutions with the GMRes algorithm depends on the dimension of the linear system, the total energy of the scattering problem, and the accuracy criterion. In several cases with dimensions in the range 1110-5632, the GMRes algorithm outperformed the LAPACK direct solver, with speedups for the linear equation solution as large as a factor of 23.

  20. Facile P-C/C-H Bond-Cleavage Reactivity of Nickel Bis(diphosphine) Complexes. (United States)

    Zhang, Shaoguang; Li, Haixia; Appel, Aaron M; Hall, Michael B; Bullock, R Morris


    Unusual cleavage of P-C and C-H bonds of the P2 N2 ligand, in heteroleptic [Ni(P2 N2 )(diphosphine)](2+) complexes under mild conditions, results in the formation of an iminium formyl nickelate featuring a C,P,P-tridentate coordination mode. The structures of both the heteroleptic [Ni(P2 N2 )(diphosphine)](2+) complexes and the resulting iminium formyl nickelate have been characterized by NMR spectroscopy and single-crystal X-ray diffraction analysis. Density functional theory (DFT) calculations were employed to investigate the mechanism of the P-C/C-H bond cleavage, which involves C-H bond cleavage, hydride rotation, Ni-C/P-H bond formation, and P-C bond cleavage.

  1. Zirconium bisamidinate complexes with sterically demanding ligands : structure, solution dynamics, and reactivity

    NARCIS (Netherlands)

    Otten, Edwin; Dijkstra, Peter; Visser, Cindy; Meetsma, Auke; Hessen, Bart


    Bisamidinate zirconium dichloride and dimethyl complexes with the sterically demanding amidinate ligands [PhC(NAr)(2))](-) (A) and [PhC(NAr)(NAr')](-) (B) (Ar = 2,6-(Pr2C6H3)-Pr-i; Ar' = 2,6-Me2C6H3) were prepared. The steric demand of ligand A induces the unusual trans geometry in trans-(A)(2)ZrCl2

  2. Developing strongly luminescent platinum(IV) complexes: facile synthesis of bis-cyclometalated neutral emitters. (United States)

    Juliá, Fabio; Bautista, Delia; González-Herrero, Pablo


    A straightforward, one-pot procedure has been developed for the synthesis of bis-cyclometalated chloro(methyl)platinum(IV) complexes with a wide variety of heteroaromatic ligands of the 2-arylpyridine type. The new compounds exhibit phosphorescent emissions in the blue to orange colour range and represent the most efficient Pt(IV) emitters reported to date, with quantum yields up to 0.81 in fluid solutions at room temperature.

  3. Hydrothermal and Solvothermal Synthesis of the Complex Fluoride α′-SrAIF5

    Institute of Scientific and Technical Information of China (English)

    贾志宏; 华瑞年; 石春山


    The complex fluoride α′-SrAlF5 has been synthesized through hydrothermal and solvothermal methods under mild conditions.The effects of the molar ratio of starting materials,temperature,reaction time and solvents on the synthesis of α′-SrAlF5 were discussed.The final products were characterized by XRD and SEM.The rod-like shape of α′-SrAlF5 is shown in SEM images.

  4. Synthesis and Characterization of Rhenium(V) Oxo Complexes Bearing PNP-Pincer Ligands

    NARCIS (Netherlands)

    Korstanje, Ties J.; Lutz, Martin; Jastrzebski, Johann T. B. H.; Klein Gebbink, Bert


    The synthesis of a series of pyridine-based PNP-pincer rhenium-oxo complexes, with phenyl (1, 3), tertbutyl (2), or cyclohexyl (4) groups on the phosphorus atoms and either a ReO2X (1, 2) or a ReCl2O (3, 4) core is reported. The structures of these compounds were characterized using H-1, C-13, and P

  5. In-situ synthesis and luminescence properties of titanium oxide gels containing 1,10-phenanthroline europium(Ⅲ) complex

    Institute of Scientific and Technical Information of China (English)

    XIE Fei; YANG Hui; XU Cun-jin; ZHANG Xi-he


    It is difficult to directly dope europium complexes in gel because the excessive water or high acidic condition may lead to their decomposition. We prepared a novel homogeneous TiO2 gel containing Eu-phen complexes by using an in-situ synthesis method. The formation of Eu-phen complexes in sol-gel derived TiO2 was confirmed by luminescence excitation spectra. The effects of temperature and aging time on in-situ synthesis are discussed. The luminescence spectra of gel containing europium complexes were also compared with the pure Eu-phen complexes.

  6. A sulfhydryl-reactive ruthenium (II complex and its conjugation to protein G as a universal reagent for fluorescent immunoassays.

    Directory of Open Access Journals (Sweden)

    Jing-Tang Lin

    Full Text Available To develop a fluorescent ruthenium complex for biosensing, we synthesized a novel sulfhydryl-reactive compound, 4-bromophenanthroline bis-2,2'-dipyridine Ruthenium bis (hexafluorophosphate. The synthesized Ru(II complex was crosslinked with thiol-modified protein G to form a universal reagent for fluorescent immunoassays. The resulting Ru(II-protein G conjugates were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE. The emission peak wavelength of the Ru(II-protein G conjugate was 602 nm at the excitation of 452 nm which is similar to the spectra of the Ru(II complex, indicating that Ru(II-protein G conjugates still remain the same fluorescence after conjugation. To test the usefulness of the conjugate for biosensing, immunoglobulin G (IgG binding assay was conducted. The result showed that Ru(II-protein G conjugates were capable of binding IgG and the more cross-linkers to modify protein G, the higher conjugation efficiency. To demonstrate the feasibility of Ru(II-protein G conjugates for fluorescent immunoassays, the detection of recombinant histidine-tagged protein using the conjugates and anti-histidine antibody was developed. The results showed that the histidine-tagged protein was successfully detected with dose-response, indicating that Ru(II-protein G conjugate is a useful universal fluorescent reagent for quantitative immunoassays.

  7. Structure and reactivities of rhenium and technetium bis-arene sandwich complexes [M(η(6)-arene)2](). (United States)

    Meola, Giuseppe; Braband, Henrik; Jordi, Sara; Fox, Thomas; Blacque, Olivier; Spingler, Bernhard; Alberto, Roger


    Sandwich complexes are important building blocks in medicinal inorganic chemistry for group 6 and 8 elements but are almost unknown for the manganese triad. We present the syntheses and full characterization of the mixed-arene (99)Tc sandwich complexes [(99)Tc(η(6)-hmbz)(η(6)-C6H5-NH3)](PF6)2 and [(99)Tc(η(6)-hmbz)(η(6)-C6H5-Br)](PF6). Both comprise functionalities for conjugation to targeting molecules or for being included as substructures in pharmaceutically active lead compounds. Since η(6)-benzene ligands are too stably bound to be replaced with incoming ligands, we prepared naphthalene complexes [Re(η(6)-C6H6)(η(6)-napht)](+) and [Re(η(6)-napht)2](+). Their reactivities towards substitution are increased and one or both naphthalene ligands can be replaced with mono- or multi-dentate ligands. Combining the features of (99)Tc and Re may lead to a molecule-based theranostic approach.


    Directory of Open Access Journals (Sweden)

    Ana Maria Abreu Velez


    Full Text Available Introduction: Dermatitis herpetiformis (DH is an autoimmune, clinically pleomorphic, papulovesicular disorder sometimes associated with celiac disease and gluten sensitivity. DH is categorized by subepidermal vesicles and bullae on hematoxylin and eosin (H&E staining, and with immunoglobulin A deposits present along the dermal papillary tips on direct immunofluorescence (DIF. Case Report: We describe a 50 year old female that presented with sudden onset pruritus and clinical blisters, predominantly on extensor areas of the extremities. Biopsies for H&E examination, as well as immunohistochemistry (IHC and DIF analysis were performed. Results: H&E examination demonstrated subepidermal blistering; within the blister lumen, numerous neutrophils were present, with occasional eosinophils and lymphocytes also seen. DIF examination revealed linear deposits of IgA along the epidermal basement membrane zone, associated with other immunoglobulins and complement. IHC examination showed similar patterns of reactivity to IgA, and also to other immunoreactants. Cells positive for CD1a were present within the blisters, correlating with S-100 staining. Cells staining positive for CD8, CD45 and occasionally CD4 and Granzyme B were seen not only in the blister lumens, but also around neurovascular packages under the blisters. Finally, CD2 positive cells were found around the upper dermal blood vessels. Discussion: Focal DIF linear IgA deposition is the classic hallmark diagnostic finding in DH. However, it is possible that genetic susceptibility and environmental triggers also play a crucial role in the pathogenesis, often acting via cellular pathways exhibiting disease-associated polymorphisms. In tolerance breakthrough, the initiating antigen presenting cells likely lead to immune system cell differentiation, and activation of adaptive immunity.

  9. Synthesis and electrochemical studies of phenylazo substituted tetraaza macrocyclic complexes of Ni(II)

    Indian Academy of Sciences (India)

    Randhir Singh; Suresh Kumar; Amarendra Bhattacharya


    Synthesis and characterization of some phenyl azo substituted tetraaza macrocyclic complexes of Ni(II) are reported. Electrochemical behaviour of these macrocyclic complexes has been examined using polarographic, voltammetric and spectroscopic techniques. These studies show that both the ligand and the metal are electrochemically active. The electrochemical behaviour of the azo function has been shown to occur through a single four-electron process. When a nitro group is also present, the nitro function of the azo moiety is reduced in a six-electron cathodic wave.

  10. Synthesis and Characterization of EDTA Complexes Useful for Trace Elements Supplementation

    Directory of Open Access Journals (Sweden)

    Baran Enrique J.


    Full Text Available The synthesis of two heterobimetallic EDTA complexes, MgCu(EDTA.6H2O and ZnCu(EDTA.6H2O, is described. They were characterized by means of vibrational (infrared and Raman and electronic (reflectance spectroscopy. Several dissolution tests in 0.1 N HCl and simulated gastric juice were also performed. The results support the potential usefulness of these complexes for copper supplementation in human and veterinary medicine and to the simultaneous reinforcement of Mg(II and Zn(II levels.

  11. Microwave Synthesis, Basic Spectral and Biological Evaluation of Some Copper (II) Mesoporphyrinic Complexes


    Rica Boscencu; Mihaela Ilie; Radu Socoteanu; Anabela Sousa Oliveira; Carolina Constantin; Monica Neagu; Gina Manda; Luis Filipe Vieira Ferreira


    Cu(II) complexes with asymmetrical and symmetrical porphyrinic ligands were synthesized with superior yields using microwave irradiation. The paper presents the synthesis of 5-(3-hydroxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl)-21,23-Cu(II)-porphine in comparison to its symmetrical complex 5,10,15,20-meso-tetrakis-(4-carboxy-methylphenyl)-21,23-Cu(II) porphine. The two compounds were characterized by FT-IR, UV–Vis and EPR spectroscopy, which fully confirmed the structures. The spectral mo...

  12. Synthesis, structural characterization and antimicrobial activity evaluation of metal complexes of sparfloxacin (United States)

    El-Gamel, Nadia E. A.; Zayed, M. A.


    The synthesis and characterization of binary Cu(II)- ( 1), Co(II)- ( 2), Ni(II)- ( 3), Mn(II)- ( 4), Cr(III)- ( 5), Fe(III)- ( 6), La(III)- ( 7), UO 2(VI)- ( 8) complexes with sparfloxacin ( HL1) and ternary Cu(II)- ( 9), Co(II)- ( 10), Ni(II)- ( 11), Mn(II)- ( 12), Cr(III)- ( 13), Fe(III)- ( 14), La(III)- ( 15), UO 2(VI)- ( 16) complexes with sparfloxacin ( HL1) and DL-alanine ( H2L2) complexes are reported using elemental analysis, molar conductance, magnetic susceptibility, IR, UV-Vis, thermal analysis and 1H-NMR spectral studies. The molar conductance measurements of all the complexes in DMF solution correspond to non-electrolytic nature. All complexes were of the high-spin type and found to have six-coordinate octahedral geometry except the Cu(II) complexes which were four coordinate, square planar and U- and La-atoms in the uranyl and lanthanide have a pentagonal bipyramidal coordination sphere. The antimicrobial activity of these complexes has been screened against two Gram-positive and two Gram-negative bacteria. Antifungal activity against two different fungi has been evaluated and compared with reference drug sparfloxacin. All the binary and ternary complexes showed remarkable potential antimicrobial activity higher than the recommended standard agents. Ni(II)- and Mn(II) complexes exhibited higher potency as compared to the parent drug against Gram-negative bacteria.

  13. Microwave Synthesis, Spectral, Thermal and Electrical Properties of Some Metal Complexes Involving 5-Bromosalicylaldehyde

    Directory of Open Access Journals (Sweden)

    Rajendra K. Jain


    Full Text Available Microwave-assisted synthesis is a branch of green chemistry. The salient features of microwave approach are shorter reaction times, simple reaction conditions and enhancements in yields. Some new Schiff base complexes of Cr(III, Co(II, Ni(II and Cu(II derived from 5-bromosalicylaldehyde with 4-nitro-1,2-phenylenediamine (H2L1 have been synthesized by conventional as well as microwave methods. These compounds have been characterized by elemental analysis, FT-IR, FAB-mass, molar conductance, electronic spectra, ESR, magnetic susceptibility and thermal analysis. The complexes exhibit coordination number 4 or 6. The complexes are coloured and stable in air. Analytical data revealed that all the complexes exhibited 1:1 (metal: ligand ratio. FAB-mass and thermal data show degradation pattern of the complexes. The thermal behavior of metal complexes shows that the hydrated complexes loses water molecules of hydration in the first step; followed by decomposition of ligand molecules in the subsequent steps. The solid state electrical conductivity of the metal complexes has also been measured. Solid state electrical conductivity studies reflect semiconducting nature of the complexes.

  14. Synthesis and Properties of Chelating N-Heterocyclic Carbene Rhodium(I) Complexes: Synthetic Experiments in Current Organometallic Chemistry (United States)

    Mata, Jose A.; Poyatos, Macarena; Mas-Marza, Elena


    The preparation and characterization of two air-stable Rh(I) complexes bearing a chelating N-heterocyclic carbene (NHC) ligand is described. The synthesis involves the preparation of a Ag(I)-NHC complex and its use as carbene transfer agent to a Rh(I) precursor. The so obtained complex can be further reacted with carbon monoxide to give the…

  15. Alpha Reactivity to Complex Sounds Differs during REM Sleep and Wakefulness (United States)

    Ruby, Perrine; Blochet, Camille; Eichenlaub, Jean-Baptiste; Bertrand, Olivier; Morlet, Dominique; Bidet-Caulet, Aurélie


    We aimed at better understanding the brain mechanisms involved in the processing of alerting meaningful sounds during sleep, investigating alpha activity. During EEG acquisition, subjects were presented with a passive auditory oddball paradigm including rare complex sounds called Novels (the own first name - OWN, and an unfamiliar first name - OTHER) while they were watching a silent movie in the evening or sleeping at night. During the experimental night, the subjects’ quality of sleep was generally preserved. During wakefulness, the decrease in alpha power (8–12 Hz) induced by Novels was significantly larger for OWN than for OTHER at parietal electrodes, between 600 and 900 ms after stimulus onset. Conversely, during REM sleep, Novels induced an increase in alpha power (from 0 to 1200 ms at all electrodes), significantly larger for OWN than for OTHER at several parietal electrodes between 700 and 1200 ms after stimulus onset. These results show that complex sounds have a different effect on the alpha power during wakefulness (decrease) and during REM sleep (increase) and that OWN induce a specific effect in these two states. The increased alpha power induced by Novels during REM sleep may 1) correspond to a short and transient increase in arousal; in this case, our study provides an objective measure of the greater arousing power of OWN over OTHER, 2) indicate a cortical inhibition associated with sleep protection. These results suggest that alpha modulation could participate in the selection of stimuli to be further processed during sleep. PMID:24260331

  16. Alpha reactivity to complex sounds differs during REM sleep and wakefulness.

    Directory of Open Access Journals (Sweden)

    Perrine Ruby

    Full Text Available We aimed at better understanding the brain mechanisms involved in the processing of alerting meaningful sounds during sleep, investigating alpha activity. During EEG acquisition, subjects were presented with a passive auditory oddball paradigm including rare complex sounds called Novels (the own first name - OWN, and an unfamiliar first name - OTHER while they were watching a silent movie in the evening or sleeping at night. During the experimental night, the subjects' quality of sleep was generally preserved. During wakefulness, the decrease in alpha power (8-12 Hz induced by Novels was significantly larger for OWN than for OTHER at parietal electrodes, between 600 and 900 ms after stimulus onset. Conversely, during REM sleep, Novels induced an increase in alpha power (from 0 to 1200 ms at all electrodes, significantly larger for OWN than for OTHER at several parietal electrodes between 700 and 1200 ms after stimulus onset. These results show that complex sounds have a different effect on the alpha power during wakefulness (decrease and during REM sleep (increase and that OWN induce a specific effect in these two states. The increased alpha power induced by Novels during REM sleep may 1 correspond to a short and transient increase in arousal; in this case, our study provides an objective measure of the greater arousing power of OWN over OTHER, 2 indicate a cortical inhibition associated with sleep protection. These results suggest that alpha modulation could participate in the selection of stimuli to be further processed during sleep.

  17. Reactive combinatorial synthesis and characterization of a gradient Ag-Ti oxide thin film with antibacterial properties. (United States)

    Unosson, Erik; Rodriguez, Daniel; Welch, Ken; Engqvist, Håkan


    The growing demand for orthopedic and dental implants has spurred researchers to develop multifunctional coatings, combining tissue integration with antibacterial features. A possible strategy to endow titanium (Ti) with antibacterial properties is by incorporating silver (Ag), but designing a structure with adequate Ag(+) release while maintaining biocompatibility has been shown difficult. To further explore the composition-structure-property relationships between Ag and Ti, and its effects against bacteria, this study utilized a combinatorial approach to manufacture and test a single sample containing a binary Ag-Ti oxide gradient. The sample, sputter-deposited in a reactive (O2) environment using a custom-built combinatorial physical vapor deposition system, was shown to be effective against Staphylococcus aureus with viability reductions ranging from 17 to above 99%, depending on the amount of Ag(+) released from its different parts. The Ag content along the gradient ranged from 35 to 62 wt.%, but it was found that structural properties such as varied porosity and degree of crystallinity, rather than the amount of incorporated Ag, governed the Ag(+) release and resulting antibacterial activity. The coating also demonstrated in vitro apatite-forming abilities, where structural variety along the sample was shown to alter the hydrophilic behavior, with the degree of hydroxyapatite deposition varying accordingly. By means of combinatorial synthesis, a single gradient sample was able to display intricate compositional and structural features affecting its biological response, which would otherwise require a series of coatings. The current findings suggest that future implant coatings incorporating Ag as an antibacterial agent could be structurally enhanced to better suit clinical requirements.

  18. DeoxyArbutin and its derivatives inhibit tyrosinase activity and melanin synthesis without inducing reactive oxygen species or apoptosis. (United States)

    Chawla, Smita; Kvalnes, Kalla; deLong, Mitchell A; Wickett, Randall; Manga, Prashiela; Boissy, Raymond E


    Safety is a major concern in developing commercial skin-lightening agents. Here, we report the modulating effects of deoxyArbutin (dA) and its second-generation derivatives - deoxyFuran (dF), 2-fluorodeoxyArbutin (fdA), and thiodeoxyArbutin (tdA) - on tyrosinase, and consequently, on melanization. Results demonstrate that dA and its derivatives inhibit tyrosine hydroxylase and dopa oxidase activity of tyrosinase. The inhibition is dose-dependent, thereby inhibiting melanin synthesis in intact melanocytes, when used at concentrations that retain 95% viability of the treated cells in culture. Herein we demonstrate that dA, and its second-generation derivatives dF, fdA, and tdA, exhibit dose-dependent reductions in melanocyte cell number, primarily due to inhibition of proliferation rather than initiation of apoptosis as exemplified by hydroquinone (HQ), ie, cytostatic as opposed to cytotoxic. Human and murine melanocytes with functional mutations in either tyrosinase or tyrosinase-related protein 1 (Tyrp1) are less sensitive to the cytostatic effects of dA and its derivatives. Minimal amounts of reactive oxygen species (ROS) were generated upon treatment with dA and its derivatives, in contrast to a dramatic amount of ROS induced by HQ. This increase in ROS subsequently induced the expression of the endogenous antioxidant catalase in treated melanocytes. Treatment with exogenous antioxidants provided protection for melanocytes treated with HQ, but not dA and its derivatives, suggesting that HQ exerts more oxidative stress. These studies demonstrate that dA and its derivatives are relatively safe tyrosinase inhibitors for skin lightening or for ameliorating hyperpigmented lesions.

  19. Synthesis and characterization of thorium(IV) and uranium(IV) complexes with Schiff bases

    Energy Technology Data Exchange (ETDEWEB)

    Radoske, Thomas; Maerz, Juliane; Kaden, Peter; Patzschke, Michael; Ikeda-Ohno, Atsushi [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Chemistry of the F-Elements


    We report herein the synthesis and characterization of several imine complexes of tetravalent thorium (Th(IV)) and uranium (U(IV)). The ligands investigated in this study are a Schiff base type, including the well-known salen ligand (H{sub 2}Le, Fig. 1). The complexation in solution was investigated by NMR measurements indicating paramagnetic effects of unpaired f-electrons of U(IV) on the ligand molecule. We also determined the solid-state molecular structures of the synthesized complexes by single crystal X-ray diffraction. The synthesized complexes show an eight-fold coordination geometry around the actinide center surrounded by two tetradentate ligands with 2N- and 2O-donor atoms.

  20. Synthesis and Characterization of Cationic Low-Valent Gallium Complexes of Cryptand[2.2.2]. (United States)

    Bourque, Jeremy L; Boyle, Paul D; Baines, Kim M


    The synthesis and characterization of two bimetallic, cationic low-valent gallium-cryptand[2.2.2] complexes is reported. The reaction of cryptand[2.2.2] with Ga2Cl4 gave two different cations, [Ga3Cl4 (crypt-222)](+) (1) or [Ga2Cl2 (crypt-222)](2+) (2), depending on whether or not trimethylsilyl triflate (Me3SiOTf) was added as a co-reagent. Complexes 1 and 2 are the first examples of bimetallic cryptand[2.2.2] complexes, as well as the first low-valent gallium-cryptand[2.2.2] complexes. Computational methods were used to evaluate the bonding in the gallium cores.

  1. Synthesis, Characterization, and Biological Activity of Nickel (II and Palladium (II Complex with Pyrrolidine Dithiocarbamate (PDTC

    Directory of Open Access Journals (Sweden)

    Sk Imadul Islam


    Full Text Available The synthesis of square planar Ni(II and Pd(II complexes with pyrrolidine dithiocarbamate (PDTC was characterized by elemental, physiochemical, and spectroscopic methods. Two complexes were prepared by the reaction of nickel acetate and palladium acetate with pyrrolidine dithiocarbamate (PDTC in 1 : 2 molar ratio. The bovine serum albumin (BSA interaction with complexes was examined by absorption and fluorescence spectroscopic techniques at pH 7.4. All the spectral data suggest that coordination of the pyrrolidine dithiocarbamate (PDTC takes place through the two sulphur atoms in a symmetrical bidentate fashion. All the synthesized compounds were screened for their antimicrobial activity against some species of pathogenic bacteria (Escherichia coli, Vibrio cholerae, Streptococcus pneumonia, and Bacillus cereus. It has been observed that complexes have higher activity than the free ligand.

  2. Synthesis, Structure, Physicochemical Properties and Catecholase-like Activity of a New Dicopper(II Complex

    Directory of Open Access Journals (Sweden)

    Neves Ademir


    Full Text Available The synthesis, characterization and catecholase activity studies of the complex [Cu2(H2bbppnol(mu-OAc(mu-ClO 4]ClO4·H2O·EtOAc containing the dinucleating ligand N,N'-2-hydroxybenzyl-N,N' -2-pyridylmethyl-2-hydroxypropane-1,3-diamine (H3bbppnol are presented here. The complex was characterized by IR, electronic and EPR spectroscopies, cyclic voltammetry, magnetic susceptibility measurements and X-ray crystallography. The catecholase-like activity of the complex was determined spectrophotometrically by monitoring the oxidation of 3,5-di-tert-butylcatechol to the corresponding o-benzoquinone in O2-saturated methanol/aqueous buffer (pH 8 mixtures at 25ºC. The complex was able to oxidize the model substrate with a turnover number of 0.0057 s-1.

  3. Synthesis and luminescence properties of iridium(III) azide- and triazole-bisterpyridine complexes. (United States)

    Goldstein, Daniel C; Peterson, Joshua R; Cheng, Yuen Yap; Clady, Raphael G C; Schmidt, Timothy W; Thordarson, Pall


    We describe here the synthesis of azide-functionalised iridium(III) bisterpyridines using the "chemistry on the complex" strategy. The resulting azide-complexes are then used in the copper(I)-catalysed azide-alkyne Huisgen 1,3-dipolar cycloaddition "click chemistry" reaction to from the corresponding triazole-functionalised iridium(III) bisterpyridines. The photophysical characteristics, including lifetimes, of these compounds were also investigated. Interestingly, oxygen appears to have very little effect on the lifetime of these complexes in aqueous solutions. Unexpectedly, sodium ascorbate acid appears to quench the luminescence of triazole-functionalised iridium(III) bisterpyridines, but this effect can be reversed by the addition of copper(II) sulfate, which is known to oxidize ascorbate under aerobic conditions. The results demonstrate that iridium(III) bisterpyridines can be functionalized for use in "click chemistry" facilitating the use of these photophysically interesting complexes in the modification of polymers or surfaces, to highlight just two possible applications.

  4. The Synthesis and Analysis of Ammine Complexes of Copper and Silver Sulfate: An Undergraduate Laboratory Project (United States)

    Clareen, Steven S.; Marshall, Shireen R.; Price, Kristin E.; Royall, Margaret B.; Yoder, Claude H.; Schaeffer, Richard W.


    An undergraduate chemistry laboratory project involving the synthesis of [Ag(NH3)2]2SO4 and Cu(NH3)4SO4 from the simple sulfate salts is described. Characterization of the stoichiometry of the complexes is accomplished by gravimetric and volumetric analysis. Silver is precipitated as the chloride and copper is precipitated as the hydroxide and converted to the oxide before weighing. The ammonia content of each complex is determined with a back titration using dilute nitric acid and sodium hydroxide. Typical student work gives results for the stoichiometry of the complexes within 1-5% of the theoretical values. The project provides a convenient preparation of two compounds whose identity and formula will not be obvious to the student. The analytical procedures illustrate the fundamentals of gravimetric and volumetric analysis and some basic characteristics of simple coordination complexes. The analytical data allow the student to determine the identity of each product by determining its empirical formula.

  5. Synthesis and structure of trinuclear W3S4 clusters bearing aminophosphine ligands and their reactivity toward halides and pseudohalides. (United States)

    Beltrán, Tomás F; Pino-Chamorro, Jose Ángel; Fernández-Trujillo, M Jesús; Safont, Vicent S; Basallote, Manuel G; Llusar, Rosa


    The aminophosphine ligand (2-aminoethyl)diphenylphosphine (edpp) has been coordinated to the W3(μ-S)(μ-S)3 cluster unit to afford trimetallic complex [W3S4Br3(edpp)3](+) (1(+)) in a one-step synthesis process with high yields. Related [W3S4X3(edpp)3](+) clusters (X = F(-), Cl(-), NCS(-); 2(+)-4(+)) have been isolated by treating 1(+) with the corresponding halide or pseudohalide salt. The structure of complexes 1(+) to 4(+) contains an incomplete W3S4 cubane-type cluster unit, and only one of the possible isomers is formed: the one with the phosphorus atoms trans to the capping sulfur and the amino groups trans to the bridging sulphurs. The remaining coordination position on each metal is occupied by X. Detailed studies using stopped-flow, (31)P{(1)H} NMR, and ESI-MS have been carried out in order to understand the solution behavior and the kinetics of interconversion among species 1(+), 2(+), 3(+), and 4(+) in solution. Density functional theory (DFT) calculations have been also carried out on the reactions of cluster 1(+) with the different anions. The whole set of experimental and theoretical data indicate that the actual mechanism of substitutions in these clusters is strongly dependent on the nature of the leaving and entering anions. The interaction between an entering F(-) and the amino group coordinated to the adjacent metal have also been found to be especially relevant to the kinetics of these reactions.

  6. Synthesis, characterization, thermal and electrical properties of composite of polyaniline with cobaltmonoethanolamine complex

    Indian Academy of Sciences (India)

    Rehana Rasool; Kowsar Majid


    The present paper involves the synthesis of polyaniline (PANI) composite with cobaltmonoethanolamine [Co(mea)2(H2O)2Cl2] complex via in situ oxidative polymerization by ammonium persulphate. The complex has been synthesized by refluxing method. The composite has been subjected to UV–Visible spectra, FT–IR, X-ray diffraction, SEM and electrical conductivity characterization techniques. Thermal analysis has been done by using TG and DSC techniques. FT–IR absorption peaks confirm the insertion of complex in the backbone of PANI. SEM of the composite also supports its successful synthesis. The XRD of composite also shows crystalline structure hence, proving the successful synthesis of PANI. Thermal analysis shows enhanced thermal stability of polyaniline. In the present composite system, the polymerization of PANI with [Co(mea)2(H2O)2Cl2] complex causes strong interfacial interactions between PANI and [Co(mea)2(H2O)2Cl2] complex crystallites, also suggested by the FT–IR and XRD studies, thereby changing the molecular conformation of PANI from compact coil structure to an expanded coil-like structure. As a consequence, there is an enhancement in the conductivity of composite of PANI up to certain dopant concentration. The anticorrosive property of a coating of PANI/[Co(mea)2(H2O)2Cl2] composite on mild steel coupon in 3 M HNO3 was evaluated using weight loss measurement and compared with pure polyaniline coating. The said composite has shown anticorrosive property and can thus, act as a potent dopant for enhancing corrosion resistance of PANI coatings.

  7. Performing organic chemistry with inorganic compounds: electrophilic reactivity of selected nitrosyl complexes. (United States)

    Doctorovich, Fabio; Di Salvo, Florencia


    The inorganic nitrosyl (NO(+)) complexes [Fe(CN) 5NO](2-), [Ru(bpy)2(NO)Cl](2+), and [IrCl 5(NO)](-) are useful reagents for the nitrosation of a variety of organic compounds, ranging from amines to the relatively inert alkenes. Regarding [IrCl 5(NO)](-), its high electrophilicity and inertness define it as a unique reagent and provide a powerful synthetic route for the isolation and stabilization of coordinated nitroso compounds that are unstable in free form, such as S-nitrosothiols and primary nitrosamines. Related to the high electrophilicity of [IrCl 5(NO)](-), an unusual behavior is described for its PPh 4(+) salt in the solid state, showing an electronic distribution represented by Ir(IV)-NO(*) instead of Ir (III)-NO(+) (as for the K(+) and Na(+) salts).

  8. Microwave Assisted Synthesis Spectral and Antibacterial Investigations on Complexes of Mn(II With Amide Containing Ligands

    Directory of Open Access Journals (Sweden)

    N. Bhojak


    Full Text Available The present research work describes the synthesis, spectral and antibacterial studies on the complexes of Mn(II with amide group containing ligands. Synthesis of complexes has been carried out by conventional method as well as by microwave method. The complexes have been characterized on the basis of elemental analysis, infrared, electronic spectra and magnetic susceptibility studies. The diffuse reflectance spectrums of the complexes show bands in the region 20,000 cm-1 to 26,000 cm-1 assignable to 6A1g → 4T2g and 6A1g → 4E1g transitions. These are also typical of tetrahedral environment around the manganese. The magnetic moment (5.80 BM of the complex indicates high spin tetrahedral environment. The microwave method of synthesis of complexes have been found easier, convenient and ecofriendly.

  9. Reactivity of copper-α-synuclein peptide complexes relevant to Parkinson's disease. (United States)

    Dell'Acqua, Simone; Pirota, Valentina; Anzani, Cecilia; Rocco, Michela M; Nicolis, Stefania; Valensin, Daniela; Monzani, Enrico; Casella, Luigi


    Parkinson's disease (PD) is a neurodegenerative disorder characterized by the presence of abnormal α-synuclein (αSyn) deposits in the brain. Alterations in metal homeostasis and metal-induced oxidative stress may play a crucial role in the aggregation of αSyn and, consequently, in the pathogenesis of PD. We have therefore investigated the capability of copper-αSyn6 and copper-αSyn15 peptide complexes, with the 1-6 and 1-15 terminal fragments of the protein, to promote redox reactions that can be harmful to other cellular components. The pseudo-tyrosinase activity of copper-αSyn complexes against catecholic (di-tert-butylcatechol (DTBCH2), 4-methylcatechol (4-MC)) and phenolic (phenol) substrates is lower compared to that of free copper(II). In particular, the rates (kcat) of DTBCH2 catalytic oxidation are 0.030 s(-1) and 0.009 s(-1) for the reaction promoted by free copper(II) and [Cu(2+)-αSyn15], respectively. On the other hand, HPLC/ESI-MS analysis of solutions of αSyn15 incubated with copper(II) and 4-MC showed that αSyn is competitively oxidized with remarkable formation of sulfoxide at Met1 and Met5 residues. Moreover, the sulfoxidation of methionine residues, which is related to the aggregation of αSyn, also occurs on peptides not directly bound to copper, indicating that external αSyn can also be oxidized by copper. Therefore, this study strengthens the hypothesis that copper plays an important role in oxidative damage of αSyn which is proposed to be strongly related to the etiology of PD.

  10. Electronic Structure of Transition Metal Clusters, Actinide Complexes and Their Reactivities

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan Balasubramanian


    This is a continuing DOE-BES funded project on transition metal and actinide containing species, aimed at the electronic structure and spectroscopy of transition metal and actinide containing species. While a long term connection of these species is to catalysis and environmental management of high-level nuclear wastes, the immediate relevance is directly to other DOE-BES funded experimental projects at DOE-National labs and universities. There are a number of ongoing gas-phase spectroscopic studies of these species at various places, and our computational work has been inspired by these experimental studies and we have also inspired other experimental and theoretical studies. Thus our studies have varied from spectroscopy of diatomic transition metal carbides to large complexes containing transition metals, and actinide complexes that are critical to the environment. In addition, we are continuing to make code enhancements and modernization of ALCHEMY II set of codes and its interface with relativistic configuration interaction (RCI). At present these codes can carry out multi-reference computations that included up to 60 million configurations and multiple states from each such CI expansion. ALCHEMY II codes have been modernized and converted to a variety of platforms such as Windows XP, and Linux. We have revamped the symbolic CI code to automate the MRSDCI technique so that the references are automatically chosen with a given cutoff from the CASSCF and thus we are doing accurate MRSDCI computations with 10,000 or larger reference space of configurations. The RCI code can also handle a large number of reference configurations, which include up to 10,000 reference configurations. Another major progress is in routinely including larger basis sets up to 5g functions in thee computations. Of course higher angular momenta functions can also be handled using Gaussian and other codes with other methods such as DFT, MP2, CCSD(T), etc. We have also calibrated our RECP

  11. Catalytic performance of symmetrical and unsymmetrical sulfur-containing pincer complexes: synthesis and tandem catalytic activity of the first PCS-pincer palladium complex

    NARCIS (Netherlands)

    Gagliardo, M.; Selander, N.; Mehendale, N.C.; van Koten, G.; Klein Gebbink, R.J.M.; Szabó, K.J.


    The synthesis and catalytic applications of a new aryl-based unsymmetrical PCS-pincer complex are reported. Preparation of the robust air- and moisture-stable PCS-pincer palladium complex 5[X] started from the symmetrical ,-dibromo-meta-xylene and involved the selective substitution of one bromide b

  12. Asymmetric synthesis of α-amino acids via homologation of Ni(II) complexes of glycine Schiff bases; Part 1: alkyl halide alkylations. (United States)

    Sorochinsky, Alexander E; Aceña, José Luis; Moriwaki, Hiroki; Sato, Tatsunori; Soloshonok, Vadim A


    Alkylations of chiral or achiral Ni(II) complexes of glycine Schiff bases constitute a landmark in the development of practical methodology for asymmetric synthesis of α-amino acids. Straightforward, easy preparation as well as high reactivity of these Ni(II) complexes render them ready available and inexpensive glycine equivalents for preparing a wide variety of α-amino acids, in particular on a relatively large scale. In the case of Ni(II) complexes containing benzylproline moiety as a chiral auxiliary, their alkylation proceeds with high thermodynamically controlled diastereoselectivity. Similar type of Ni(II) complexes derived from alanine can also be used for alkylation providing convenient access to quaternary, α,α-disubstituted α-amino acids. Achiral type of Ni(II) complexes can be prepared from picolinic acid or via recently developed modular approach using simple secondary or primary amines. These Ni(II) complexes can be easily mono/bis-alkylated under homogeneous or phase-transfer catalysis conditions. Origin of diastereo-/enantioselectivity in the alkylations reactions, aspects of practicality, generality and limitations of this methodology is critically discussed.

  13. Physico-Chemical and In-vitro Microbial Studies of Newly Synthesis Organometallic Complexes

    Directory of Open Access Journals (Sweden)

    Isam Hussain Al-Karkhi


    Full Text Available Drugs normally synthesized to use as medication to treat diseases like cancer and microbial infections, these synthesized drugs were interested more than naturally-derived drugs which have been shows low activity or not as efficient against diseases. A new ligand 3-methylbenzyl (2Z-2-[1-(pyridin-4-ylethylidene]hydrazine carbodithioate (PE3MBC and its Cd(II, Cu(II, Co(II and Zn(II metal complexes. The new ligand and metal complexes were characterized via various physico-chemical and spectroscopic techniques. Cd(II complex show more activity against microbes and against cancer cell line MCF-7, while other complexes does not shows activity like cadmium complex, all the complexes does not shows any activity against MDAMB-231 cell line. The fatal of the cancer and the microbes cell was due to inhibition of DNA synthesis which was probably due to chelating with metals complexes, or could be referred to lipophilicity, presence of hydrophobic moiety in the complex molecule, also could be due to steric effects and electronic effects.

  14. Experimental Aspects of Synthesis

    CERN Document Server

    Ehlers, Rüdiger


    We discuss the problem of experimentally evaluating linear-time temporal logic (LTL) synthesis tools for reactive systems. We first survey previous such work for the currently publicly available synthesis tools, and then draw conclusions by deriving useful schemes for future such evaluations. In particular, we explain why previous tools have incompatible scopes and semantics and provide a framework that reduces the impact of this problem for future experimental comparisons of such tools. Furthermore, we discuss which difficulties the complex workflows that begin to appear in modern synthesis tools induce on experimental evaluations and give answers to the question how convincing such evaluations can still be performed in such a setting.

  15. Message survival and decision dynamics in a class of reactive complex systems subject to external fields (United States)

    Rodriguez Lucatero, C.; Schaum, A.; Alarcon Ramos, L.; Bernal-Jaquez, R.


    In this study, the dynamics of decisions in complex networks subject to external fields are studied within a Markov process framework using nonlinear dynamical systems theory. A mathematical discrete-time model is derived using a set of basic assumptions regarding the convincement mechanisms associated with two competing opinions. The model is analyzed with respect to the multiplicity of critical points and the stability of extinction states. Sufficient conditions for extinction are derived in terms of the convincement probabilities and the maximum eigenvalues of the associated connectivity matrices. The influences of exogenous (e.g., mass media-based) effects on decision behavior are analyzed qualitatively. The current analysis predicts: (i) the presence of fixed-point multiplicity (with a maximum number of four different fixed points), multi-stability, and sensitivity with respect to the process parameters; and (ii) the bounded but significant impact of exogenous perturbations on the decision behavior. These predictions were verified using a set of numerical simulations based on a scale-free network topology.

  16. Drone based structural mapping at Holuhraun indicates fault reactivation and complexity (United States)

    Mueller, Daniel; Walter, Thomas R.; Steinke, Bastian; Witt, Tanja; Schoepa, Anne; Duerig, Tobi; Gudmundsson, Magnus T.


    Accompanied by an intense seismic swarm in August 2014, a dike laterally formed, starting under Icelands Vatnajökull glacier, propagating over a distance of more than 45 km within only two weeks, leading to the largest eruption by volume since the 1783-84 Laki eruption. Along its propagation path, the dike caused intense surface displacements up to meters. Based on seismicity, GPS and InSAR, the propagation has already been analysed and described as segmented lateral dike growth. We now focus on few smaller regions of the dike. We consider the Terrasar-X tandem digital elevation map and aerial photos and find localized zones where structural fissures formed and curved. At these localized, regions we performed a field campaign in summer 2015, applying the close range remote sensing techniques Structure from Motion (SfM) and Terrestrial Laser Scanning (TLS). Over 4 TLS scan were collected, along with over 5,000 aerial images. Point clouds from SfM and TLS are merged and compared, and local structural lineaments analysed. As a result, we obtained an unprecedentedly high-resolution digital elevation map. With this map, we analyse the structural expression of the fissure eruption at the surface and improve understanding on the conditions that influenced the magma propagation path. We elaborate scenarios that lead to complexities of the surface structures and the link to the underlying dike intrusion.

  17. Complexity of Host Micro-RNA Response to Cytomegalovirus Reactivation After Organ Transplantation. (United States)

    Egli, A; Lisboa, L F; O'Shea, D; Asberg, A; Mueller, T; Emery, V; Kumar, D; Humar, A


    Human (Homo sapiens) micro-RNAs (hsa-miRNAs) regulate virus and host-gene translation, but the biological impact in patients with human cytomegalovirus (hCMV) infection is not well defined in a clinically relevant model. First, we compared hsa-miRNA expression profiles in peripheral blood mononuclear cells from 35 transplant recipients with and without CMV viremia by using a microarray chip covering 847 hsa-miRNAs. This approach demonstrated a set of 142 differentially expressed hsa-miRNAs. Next, we examined the effect of each of these miRNAs on viral growth by using human fibroblasts (human foreskin fibroblast-1) infected with the hCMV Towne strain, identifying a subset of proviral and antiviral hsa-miRNAs. miRNA-target prediction software indicated potential binding sites within the hCMV genome (e.g., hCMV-UL52 and -UL100 [UL = unique long]) and host-genes (e.g., interleukin-1 receptor, IRF1). Luciferase-expressing plasmid constructs and immunoblotting confirmed several predicted miRNA targets. Finally, we determined the expression of selected proviral and antiviral hsa-miRNAs in 242 transplant recipients with hCMV-viremia. We measured hsa-miRNAs before and after antiviral therapy and correlated hsa-miRNA expression levels to hCMV-replication dynamics. One of six antiviral hsa-miRNAs showed a significant increase during treatment, concurrent with viral decline. In contrast, six of eight proviral hsa-miRNAs showed a decrease during viral decline. Our results indicate that a complex and multitargeted hsa-miRNA response occurs during CMV replication in immunosuppressed patients. This study provides mechanistic insight and potential novel biomarkers for CMV replication. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.

  18. Synthesis, characterization, and biological activity of a new palladium(II) complex with deoxyalliin

    Energy Technology Data Exchange (ETDEWEB)

    Corbi, P.P.; Massabni, A.C. [Inst. de Quimica - UNESP, Dept., Dept. de Quimica Geral e Inoganica, Araraquara (Brazil)]. E-mail:; Moreira, A.G. [Inst. de Quimica - UNESP, Dept. de Quimica Geral e Inoganica, Araraquara (Brazil); Faculdade de Medicina de Ribeirao Preto - USP, Dept. de Bioquimica e Imunologia, Ribeirao Preto (Brazil); Medrano, F.J. [Laboratorio Nacional de Luz Sincrotron - LNLS, Campinas (Brazil); Jasiulionis, M.G. [Escola Paulista de Medicina - UNIFESP, Dept. de Micro-Imuno-Parasitologia, Sao Paulo (Brazil); Costa-Neto, C.M. [Faculdade de Medicina de Ribeirao Preto - USP, Dept. de Bioquimica e Imunologia, Ribeirao Preto (Brazil)


    Synthesis, characterization, and biological activity of a new water-soluble Pd(II)-deoxyalliin (S-allyl-L-cysteine) complex are described in this article. Elemental and thermal analysis for the complex are consistent with the formula [Pd(C{sub 6}H{sub 10}NO{sub 2}S){sub 2}]. {sup 13}C NMR, {sup 1}H NMR, and IR spectroscopy show coordination of the ligand to Pd(II) through S and N atoms in a square planar geometry. Final residue of the thermal treatment was identified as a mixture of PdO and metallic Pd. Antiproliferative assays using aqueous solutions of the complex against HeLa and TM5 tumor cells showed a pronounced activity of the complex even at low concentrations. After incubation for 24 h, the complex induced cytotoxic effect over HeLa cells when used at concentrations higher than 0.40 mmol/L. At lower concentrations, the complex was nontoxic, indicating its action is probably due to cell cycle arrest, rather than cell death. In agreement with these results, the flow cytometric analysis indicated that after incubation for 24 h at low concentrations of the complex cells are arrested in G0/G1. (author)

  19. Hemoglobin-biocatalyzed Synthesis of Conducting Molecular Complex of Polyaniline and Lignosuifonate

    Institute of Scientific and Technical Information of China (English)

    HU Xing; LIU Shenggui; ZHAO Mingming; ZOU Guolin


    A new biocatalyst route for the synthesis of a conducting polyaniline (PANI)/lignosulfonate (LGS) complex was presented.Four different catalysts such as hemoglobin (Hb),5,10,15,20-tetrakis (meso-hydroxyphenyl) porphyrin,iron (Ⅱ) tetrasulfophthalocyanine and ferric chloride were used to polymerize aniline in the presence of a natural polyelectrolytes template LGS.The experimental results show that Hb is an effective catalyst in this case and the synthesis is simple,and the conditions are mild in that the polymerization may be carried out in lower pH (1.0-4.0) buffered solution and optimal pH of 2.0.Varying concentrations of aniline,LGS and H2O2 in feed the favorable conditions for the production of PANI were determined.UV-vis absorption,FFIR,elemental analysis,conductivity,cyclic voltammetry and thermogravimetric analyses confirm the formation of thermally stable and electroactive PANI.

  20. Nitrogen-Phosphorus(III)-Chalcogen Macrocycles for the Synthesis of Polynuclear Silver(I) Sandwich Complexes. (United States)

    Yogendra, Sivathmeehan; Hennersdorf, Felix; Weigand, Jan J


    The synthesis of inorganic N-P(III)-Ch-based macrocycles [-PhP-NMe-PPh-Ch-]2 (8Ch; Ch = S, Se) is presented by incorporating two nitrogen, two chalcogen, and four phosphorus atoms. The macrocycles are conveniently obtained via the cyclocondensation reaction of Na2Ch (Ch = S, Se) with the acyclic dichlorodiphosphazane ClPhP-NMe-PClPh (9). Treatment with elemental sulfur (S8) or gray selenium (Segray) results in an oxidative ring contraction to give 1,3,2,4-thiazadiphosphetidine 2,4-disulfide (10S) and 1,3,2,4-selenazadiphosphetidine 2,4-diselenide (10Se), respectively. Macrocycles 8Ch are excellent multidentate ligands for transition metal complexation, as demonstrated by the isolation of mono-, di- tri-, and tetranuclear silver sandwich complexes. The polynuclear silver complexes are comprehensively characterized, including detailed NMR and X-ray analysis.